CA1180859A - Method and apparatus for producing hollow metal microspheres and microspheroids - Google Patents

Abstract

ABSTRACT OF THE INVENTION
Hollow metal microspheres for manufacture of superior high strength light weight structural materials are described. The microspheres are made by forming a liquid film of molten film forming metal composition across a coaxial blowing nozzle and applying a blowing gas at a positive pressure on the inner surface of the metal film to blow the film and form an elongated cylinder shaped liquid film of molten metal. A transverse jet directs an inert entraining fluid over and around the blowing nozzle, which produces asymmetric fluid drag forces on the elongated molten metal cylinder and closes and detaches the cylinder from the coaxial blowing nozzle, the cylinder then forming into a spherical shape by surface tension forces. Quench nozzles direct cooling fluid at the molten metal microspheres to rapidly cool and solidify them. The hollow metal microspheres may contain a thin metal coating deposited on their inner wall surfaces by appropriate selection of blowing gas. The metal microspheres can be used to make improved insulation materials and insulating systems or can be used as filler materials in plastics or rubber or compositions thereof or in metal compositions.

Description

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SUM~RY OF THE I~VENTION

The present invention relates to hollow microspheres made from film forming metal materials and compositions and particularly to hollow metal glass microspheres and to a process and apparatus for making the microspheres.
The present invention also relates to hollow metal microspheroids and to a method and apparatus for making hollow metal microspheroids.
The present invention also relates to hollow metal vacuum microspheres having a thin metal coating deposited on the inner wall surface of the microsphere.
The present invention relates to hollow metal microspheres for use as light weight structural materials, as filler materials in plastics and in plastic foam compositions and metal compositions.
The present invention relates to a method and apparatus for using a coaxial blowing nozzle to blow microspheres from liquid film forming metal compositions comprising subjecting the microsphere during its formation to an external pulsating or fluctuating pressure field having periodic oscillations, said pulsating or fluctuating pressure field acting on said microsphere to assist in its formation and to assist in detaching the microsphere from said blowing nozzle.

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The invention particlllarly relates to a method and apparatus for blowing the microsphere6 from metal glass , compositions and particularly to blowing microsphere.s from a molten metal glass compositions using a coaxial 5 blowing nozzle and an inert blowing gas or a metal vapor to blow the molten metal to form a llollow metal glass microspheres.
The invention also relates to a method and apparatus for blowing the microspheres from film forming liquld metal compositions using a coaxia?L blowing nozzle and a blowing gas or a blowing gas cont.aining dispersed metal particles and/or an organo me~al compound to blow the liquid metal to ~orm a hollow metal microsphere. The metal particles deposit and/or the organo metal compound -i decomposes to deposit a ~hin metal coating orl the inner wall surface of the metal microsphere.
A transverse jet is used to d~Lrect an inert entraining fluid over and around the blowing nozzle at an angle to the axis of the b].owing nozzle. The entraining fluid as it passes over and aroun~ the blowing nozzle envelops and acts on the molten ~ilm forming metal as it is being blown to ~orm the microsphere and to detach the microsphere from the coaxial blowing nozzle. Quench means are disposed close to and below the blowing nozzles to direct a quench fluid onto the microspheres to rapidly cool and solidify the microspheres.
The present invention specifically relates to the use of the hollow metal microspheres and the hollow metal glass microspheres in the manufacture of superior high strength, light weight structural m~erials for use in construction and in the manufacture of products in which high strength light weight materials are desired or necessary .
The present invention specifically ~elates to the use of ~he hollow metal microspheres as filler materials in syntactic foam s~stems.

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The present invention also relate3 to a method and apparatus for making filamented metal microspheres with thin metal filaments connecting adjacent microspheres and to the filamented microspheres themselves, The hollow metal microspheres of the presen~
invention, depending on their diameter and their wall thickness and the particular metal composition from which they are made, are capable of withstanding relatively high external pressures and/or weight.
Hollow metal microspheres can be made that are stable at relatively high ~emperatures and resistant to many chemica~ agents and weathering conditions. These characteristics make the microspheres suitable for a wide ~ariety of uses.
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~ACKGROUND OF T~E INVENTION
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In recent years, the substantial increases in c08ts of basic materials such as metals,metal alloys, plastics, rubbers and the like h~.s encouraged development and use of light weight s~ructural ma~erials, s~rength adding materials and of filler materials to reduce the amount and cost of the basic materials used and the weight of the finished materials;
The known methods ~or producing hollow metal micro-spheres have not been successful in producing micro-spheres of rela~ively uniform size or uniform thin walls which makes it very difficult to produce materials of controlled and preditable characteristies, quality and - strength.
One of the existing me~hod o~ producing hollow metal spheres is disclosed i.n the Hendricks U.S.
Patent 4,133,854. The method disclosed involves dis-persing a blowing gas preeursor material in the metal to be blown to form the microspheres. The ma~erial contain-ing the blowing,gas precursor enclosed therein is ~hen heated to convert the precursor material to a gas and is fur~her heated to expand the gas and produce the hollow microsphere containing therein the expanded gas. Another process or making hollow metal spheres is disclosed in Niimi et al, U.S. Patent 4,021,167, This method involves dropping molten metal stream through a nozzel, passing the ~lolten jet metal through a linear water jet which fragments the molten metal into droplets and tr~ps water droplets in the drople~s of molten metal. The trapped water droplets expand inside the molten metal droplets to thereby form hollow mPtal particles.

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-These processes, par~icularly the Niimi et al process, are understandably difficult to control and ' of necessity, i e. inheren~ly, produce spheres ~ary-ing in size and wall thickness, spheres with walls that have sections or portions of the walls that are relatively thin, walls that have holes, small trapped bubbles, trapped or dissolved gases, any one or more of which will result in a substantial weakening of thP
microspheres, and a substantial number or proportion of microspheres which are not suitable for use and must ~e scrapped or recycled In addition, the filamented microspheres of the present invention provide a convenient and safe method of handling the microspheres.
~ The known methods for producing hollow metal microspheres have not been successful in producing microspheres of uniform size or uniform thin walls a~d in producing hollow metal microspheres of controlled and predictable physical and chemical characteri.stics, quality and strength.

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_~_ OBJECTS OF l~lE INVENTION
. _ _ _ It is an object of the present inven~ion to provide ~ process and an apparatus for making hollow metal microspheres.
It is another object of the present invention to utilize the hollow metal microspheres o~ the present invention in ~he manufacture of improved ~tructural materials and structural ~ys~ems.
It is another object of the present invention to make hollow metal microspheres for use as and/or in filler materials.
It is another object of the presen~ invention to produce hollow metal microspheres having uniform thin walls which walls are su~s~antially free of trapped gas ~bbles or dissolved gases which can form bubbles and/or escape.
It is another object of the present invention to produce hollow metal microspheres which are substantially resistant weathering, chemical agents and alkali materials.
It is stlll another object of the present invention to utilize the hollow metals microspheres in the manufacture ~f syntactic foam systems and/ox molded forms or shapes.
It is another object of the present in~ention to produce hollow metal vacuum microspheres having depo~ited on the inner wall surace thereof a th~n metal coating.
It is another obiect of ~he present invention to produce in an economical simple manner hollow metal mlcrospheres which are substantially uniform in diameter, wall thickness and strength characteristics.
It is another obje~t of the present invention ~o utiliæe the metal gla~s microspheres of the present invention in ~he manufacture of superior, high strength, light weigh~
structural materials andlor for use in the manufacture of formed shapes, e.g. structural members and wall panels.

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_g _ It is another ob~ect of the present invention to .produce hollow metal fi:lamented microspheres and filamented microspheroids with a thin metal ~ilament connecting adjacent metal microspheres and rnicrospheroids.
S It is still another object of the present inven-tion to utilize the hollow metal microspheres of ~he present invention in the. manu~acture of insulation materials and insulating systems.

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i BRIEF DESCRIPTION OF THE INVENTION
~ The present invention relates to hollow me~al microspheres and to a process and apparatus for making the microspheres. The present invention more par~icularly relates to the use of hollow metal glass microspheres in the manuacture of superior high strength, light wei~ht structural materials and systems, and as improved filler materials.
The microspheres are made from a film forming metal composition and can contain a gas at a relatively low pressure. The microspheres can also be made to contain a high vacuum and a thin me~al coating deposited on the innPr wall surface of the microspheres.
~ The microspheres can also be made to contain a gas at above or below or at about ambien~ pressure and a thin metal coating deposited on the inner wall surface of the microspheres.
The internal metal coating can be reactive with or inert to the metal from which the microsphere is formed.
The metal microspheres of the present invention ~an be used to form a heat barrier by forming them into sheets or other shaped forms to be used as insulation barriers.
The hollow metal glass microspheres of the present invention are made by forming a liquid film of mol~en metal material across a coaxial blowi.ng nozzle, applying an inert gas or metal vapor at a positive pressure on the inner surfaee of the metal film to blow the film and form an elongated cylinder shaped liquid film of molten metal which is closed at its outer end.
The hollow metal microspheres of the present invention can also be made by applying a gas or a gas containing dispersed metal particles and/or a gaseous organo metal compound at a positive pressure to the inner sur~ace of the metal film to blow the film and form an elonga~ed cyllnder shaped liquid ~ilm of metal which i8 ~closed at its ou~er end. A balancing but slightly lower ~as pressure is provided in the area of ~he blowing nozzle into which ~he elongated cylinder shaped liquid metal film is blown.
A transverse jet is used to direct an entraining fluid over and around the blowing nozæle a~ an angle to the axis of the blowing nozzle, The entraining fl~id as it passes over and around the blowing nozzle and the elongated cylinder fluid dynamically induces a pulsating or fluctuating pressure field a~ the opposite or lee side of the blowing nozzle in the wake or shadow of the blowing nozzle, The fluctuating pressure field has ~egular periodic lateral oscillations similar to those lS of a flag flapping in a breeze.
The transverse jet entraining fluid can also be pulsed at regular intervals to assist in controlling the size of the microspheres and in separating the micro~
spheres from the blowing nozæle and the distance or 20 spaci~g between microspheres.
~ The entraining fluid envelops and ac~s asymmetrically on the elongated cylinder and causes ~he cylinder to flap, fold, pinch and close-off at its inner end at a point proxi.mate to the coaxial blowing nozzle. The continued movement of the entraining fluid over the elongated cylinder produces fluid drag forces on the cylinder and detache.s the elongated eylinder from the coaxial blowing nozzle to have it fall free from the blowing nozæle. The sur:Eace tension forces of the molten metal act on the now free, entrained elon~ated cylinder and cause the cylinder to seek a minimum sur~ace area and to form a spherical shape.
Quench;n-ozzles are disposed below and on either side o~ the blowing nozzle and direct cooling fluid a,t and into contact wi~h the molten ~eta~ microspheres .. _ ._ . . . . . _" . ,, _ . __ _ _ ..

5~3 to rapidly cool and solidi~y the molten metal and ~orm a hard, smooth hollow metal microsphere. I~here a metal ~apor is used a~ a blowing gas to blow the micro.spheres, the quench fluid cools and condenses ~he metal vapor and causes the metal vapor to deposit on ~he inner wall surface of the microsphere~ as a thin metal coa~ing.
In one embodiment of the invention, ~he microspheres are coated wi~h an adhesive or foam filler and flattened to an oblate spheroid or a generally cellular shape. The microspheres are held in the flattened position until the adhesive hardens and/or cures after which the micro-spheres retain their flattened shape. The use of the flattened microspheres substantially reduces the vol.ume Qf the interstices between the microspheres and signifi-cantly improves the strength characteristics of themicrospheres.
The microspheres can be made from film forming metal compositions selected for their desired strength and chemical resistant properties and for the particular uses intended for the mierospheres.
~ Where a gas containing dispersed metal particles is used to blow the microspheres, a metal layer is deposited on the inner wall surface of the microsphere as a thin metal coating. Where a gaseous organo metal compound is used to deposit the metal layerl a gaseous organo metal compound is used as or with the blowing gas to blow the microspheres. The organo metal compound can be decomposed just prior to blowing the microspheres or after the microspheres are formed by, for example, sub jecting the blowing gas or the microspheres to heat and/or an electrical discharge.
The filamented microspheres are made in a manner such that they are connected or attached ~o each other by a thin continuous metal ~ilament, The method of ma~ing the filamen~ed mi.crospheres can be carried out to obtain filamented microspheroids, in the manner cliscussed more fully below. The filamented microspheres can also be flattened to produce the obIate spheroids. The filaments interrupt and reduce the area of wall to wall contact between the microspheres. The filame,nted microspheres also assist in handling and preventing scattering of microspheres, particularly wher2 very small diameter microspheres or low density microspheres are pro~uced.
The filamented microspheres have a distinct advantage over the simple addition of filaments in that the con-tinuous filaments do not tend to settle in the system in which they are used.

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TIIE ADVANlAGES:;
~ The present invention overcomes many of ~he problems associated with prior attempts to produce hollow metal microspheres. The process a.nd apparatus of the present invention allows the production of hollow metal micro-spheres h~ving predetermined characteristics such that superior high strength, light weight s~ructural materials and systems~ and improved filler materials can be designed, manufactured and tailor made to suit a particular desired 1~ use, The diameter, wall thickness and unifol~ity and the strength and chemieal resistance characterist:îcs o~ the microspheres or microspheroids can be determi.ned by care-fully selecting the constituents of the metal composition a~ controlling the inert gas or mecal vapor pressure and the temperature, and ~he temperature, viscosity, surface tension, and thickness of the molten metal film from which the microspheres are ~ormed. The inner volume of the microspheres may contain an inert low heat conductivi~y gas used to blow the microsphere or can contain a hi.gh vacuum produced by condensing a metal vapor used to blow the microsphere.
The process and apparatus of the present invention provide a practical and economical means by which hollow metal microspher~s can be utilized to prepare a relatively low costr high strength, light weight. structural material for every day uses.
The apparatus and process of the present invention also provide for the production of hollow metal microspheres at economic prices and in large quantities.
The process and apparat1ls o the presen~ invention, as compared to the prior art processes of using a latent liquid or solid blowing agent, can be conducted at .higher temperatures since there is no included expandable and/or decomposable blowing agent used~ The ability to use hig~er blowing temperatures results in for particular metal 5~3 compositions a lower metal viscosity which allows surface tension forces to produce significantly greater uniormity ~n wall thickness and diameter of the microspheres produced.
The process ad apparatus o the present invention allow the ~se of a wide variety of blowing gases and blow-ing gas materials to be used and encapsulated.
The present invention provides a method for using a metal vapor blowing gas to blow hollow me~al microspheres to obtaîn a high contained vacuum within the microsphere.
The present invention also allows for the addition to metal vapor blowing gas smaLl amounts of selec~ed metal vapors, e.g. alkali metal vapors, to getter, i.e. react with trace gases that may evolve from the molten metal film as the microsphere is being formed. The selected m~tal vapors getter any evolved gases and rnaintain the high contained vacuum.
The process and apparatus of the present invention allows the production of hollow metal microspheres for structural, insulation and/or filler uses having pre-determined diameters, wall thicknesses, strength andresistance to chemical agents and weathering and gas permeability such that superior systems can be designed, manufactured and tailor made to suit a p~rticular desired use. In addition, the surface of the hollow metal micro-spheres, because of the method by which ~hey are made, dono ~

BRIEF DESCRIPTION OF TH~ DRAWINGS
The attached drawings illustrate exemplary forms of the method and appara~us of ~he presen~ inven~ion for making microspheres for use in and as structural materials and/or for use in and as filler materials.
The Figure 1 of the drawings shows in cro~s-section an apparatus having multiple coaxial blowing noæzle means for supplying the gaseous material for blowing hollow metal microspheres, a transverse ~et providing an entrain-ing fluid ~o assist in the formation and de~achment of the microspheres from the blowing nozzles, and means for supply-ing a quench fluid to cool the microspheres.
The Figure 2 of the drawings is an enlarged detailed cross-section of the nozzle means of apparatus shown in Figure 1.
The Figure 3 of the drawings is a detailed cross-section of a modified form of the nozzle means shown in Fi~ure 2 in which the lower end of ~he nozzle means is tapered inwardly and which is provided with a heating coil.
The Figure 3a of the drawings ls a detailed cross-section of a modified transverse jet entraining means having a flattened orifice opening and the Figure 3 nozzle means.
The Figure 3b o the drawings is a top plane view of the modified transverse jet entraining means and the nozzle means illustra~ed in Figure 3a of the drawings.
The Figure 3c of the drawings illustrates the use of the apparatus of Figure 3b to make filamented hollow me~al microspheres.
The Figure 4 of the drawings is a detailed cross-section of a modified form of the nozzle means shown in Figure 2 in which the lower portion of the nozzle is enlarged.

~3 ' , The Figure 5 o~ the drawings shows a cross-section of a mass o~ spherical shaped hollow metal microspheres fused or bonded together in a shaped ~orm.
The Figure 6 of the drawings shows a cross-sec~ion of a mass of oblate spheroid shaped hollow metal filamented microspheres fused or bonded together in a shaped form in which filaments interrupt the microsphere wall ~o wall contact.
The Figure 7 of ~he dra~Jings shows a cross-sec~ion of spherical shaped hollow metal microspheres madP into a formed structual paneI in which the inters~esare filled with a fused powdered metal or a hardened molten metal or a plastic material.
~, The Figure 7a of the drawings shows a cross-section o oblate spheroid shaped hollow metal microspheres made into a formed structural pane~ in which the inter~tices are filled with a fused powdered metal o~ a hardened molten metal or a plastic.
The Figure 7b of the drawings shows a cross-section ~0 of oblate spheroid shaped hollow me~al filamented micro-~pheres made into a formed structural panel in which the inter~s~ces are filled with a fused powdered metal or a hardened molten metal or plas~ic and the fi.laments extend through the inter~ces and interrupt the microsphere wall to wall contact.
The Fi.gure 8 of the drawings illustrates in graphîc form the rela~ionship between the thickness of the thin metal film, e.g. a zinc film, deposited on the inner wall surface of the hollow microsphere, ~he metal vapor blowing gas pressure and the diameter* of the microspheres.
* ~or~~he purpo~s-e~s of the graphic illustration, the ~nside and outside diameter of the microspheres are considered to be about the same.

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DETAILED DISCUSSION OF THE DRAWINGS
The invention will be described wlth reference to ~he accompanying Figures l to 4 of the drawings wherein like numbers designate like par~ throughout the several views.
Re~erring to Figures 1 and 2 of the drawings, there is illustrated a vessel 1, made of suitable refractory material and heated by means not shown for holding molten film forming meta~ material 2. The bot~om 100r 3 of vessel 1 contains a plurality of openings 4 through which molten metal 2 is fed to coaxial blowing nozzles 5. Th~
coaxial blowing nozzle 5 can be made separately o-r can be. formed by a downward extension of the bottom 3 of ~e~sel 1. The coaxial blowing nozzle 5 consists of an inn~r nozzle 5 having an orifice 6a for a blowing gas, an inert blowing gas or metal vapor blowing gas and an outer noæzle 7 having an orifice 7a for molten metal. The inner nozzle 6 is disposed within and coaxial to outer nozzle 7 to form annular space 8 between nozzles ~ and 7, which annular space provides a flow path for molten ~lass 2. The orifice 6a of inner nozzle 6 terminates at or a short distance above the plane of orifice 7a of outer nozzle 7.
The molten metal 2 at about atmospheric pressure or at elevated pressure flows downwardly through annul~r space 8 and fills th~, area between ori~ice 6a and 7a. The surface tension orces in the molten metal 2 form a thin liquid molten metal film 9 across orifice 6a and 7a.
A blowing gas 10, inert blowing gas, metal vapor blowing gas and/or a blowing gas contalning dispexsed metal partlcles, which is heated by means not shown to about the temperature of the mol~en me~al and which is at a pressure above the molten metal pressure at the blowing nozzle, is fed through distribution conduit ll and inner ~oaxial nozzle 6 and brought into con~act with the inner 8S~`3 . . , ;?~.~
surface of molten metal film 9. The blowing gas or metal vapor exerts a positive pressure on thei molten metal fil~ to blow and distend the film outwardly to form an elongated cylinder shaped liquid film 1~ of molten metal filled with the blowing gas.or metal vapor 10. The elongated cylinder 12 i5 closed at i~s outer end and is connected at its inner end to outer nozæle 7 at the peripheral edge of orifice 7a. A
balancing pressure of a gas or of an inert gas, i.e. a slightly lower pressure, is provided in the area o~
the blowing nozzle into which the elongated cylinder shaped liquid film is blown The illustrated coaxial nozzle can ~e used to produce microspheres having diameters three to five times the-size of the inside diameter of orifice 7a and is useful in blowing low viscosity metal materials.
A transverse jet 13 is used to direct an inert entraining fluid 14, which is heated to about, below or above the temperature of the molten metal 2, by means not shown. The entraining fluid 14 is fed through ; distribution conduit lS, noæzle 13 and transverse jet nozzle orifice 13a and directed at the coaxial blowing nozzle 5~ The transverse jet 13 iACi aligned to direct the flow of entraining fluid 14 over and around blowing noæzle 7 in the microsphere forming region at and behind the. orifice 7a. The entraining fluid 14 as it passes over and around blowing nozzle 5 1uid dynamically induces a pulsating or fluctuating pressure field in the entraining fluid 14 at the opposite or lee side of blow-ing nozzle 5 in its wake or shadow.
The entraining fluid 14 envelops and acts on ~heelongated cylinder 12 in such a manner as to cause the cylinder to flap, fold,pinch and close-off at i~s inner ` end at a point 16 proxim~e to the orifice 7a of outer nozzle 7. The continued movemen~ of the entraining v~

fluid 14 over the elongated cylinder 12 produces fluid drag forces on the cylinder 12 and detaches it from the i orifice 7a of the outer noæzle 7 to allow the cylinder to fall, i.e. be entrained and transported away from noæzle 7. The surface tension orces of the molten metal act on the entrained, falling elongated cylinder 12 and cause the cylinder to seek a minimum surface area and to form a spherical shape hollow molten metal microsphere 17.
Quench nozzles 18 having orifices 18a are disposed below and on both sides of coaxial blowing nozzle 5 and direct cooling fluid 19 at and into contac~ with the molten metal microsphere 17 to rapidly cool and solidify the molten metal and form a hard, smooth hollow metal -~. microsphere. The quench fluid 19 also serves to carry the hollow metal microsphere away from ~he coaxial blowing nozzle 5. Where a metal vapor is used as a blowing gas to blow the microspheres, the quench fluid cools and condenses the metal vapor to deposit the metal vapor on the inner wall surface of the microsphere as a thin metal coating 20. The cooled and solidified hollow metal microspheres are collected by suitable means not shown.
The Figure 3 of the drawings illustrates a pre-ferred embodiment of the invention in which the lower portion of the outer coaxial nozzle 7 is tapered down-wardly and inwardly at 21. This embodiment as in the previous embodiment comprises coaxial b].owing nozzle 5 which consists of inner nozzle 6 with orifice 6a and outer nozzle 7 with ori~ice 7a'. The figure of the drawings also shows elongated cylinder shaped liquid film 12 with a pinched portion 16. This figure of the drawings also shows a heating coil 8a by which the temperature of the film formin~ molten metal material can be accurately controll~d:up tv th~ me i~ is blown to form the hollow metal microspheres.

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The use of the tapered nozzle 21 construction was found to substanti.ally assist in the forMation of a thln molten metal film 9' in the area between orifice 6a of inner nozæle 6 and orifi.ce 7a' of outer nozzle 7. The inner wall surface 22 of the taper portion 21 o~ the outer nozzle 7 when pressure is applied to molten metal 2 forces the molten metal

2 to squeeze through a fine gap formed between the outer edge of orifice 6a, i.e. the outer edge of the inner n~zzle and the inner surface 22 to fonm the thin molten metal ~ilm 9' across orifice 6a and 7a'. l~us, the formation of the molten film 9' does not in this embodiment rely solely on ~he surface tension properties of the molten metal. The illustrated coaxial nozzle ~can be used to produce microspheres having diameters three to five times the size of the diameter of orifice 7a of coaxial nozzle 7 and allows making ~icrospheres of smaller diameter ~han those made using ~he Flgure 2 apparatus and is particularly useful in blowing high viscosity metal materials.
The diameter of the microsphere i5 determined by the diameter of orifice 7a'. The apparatus allows the use of larger inner diameters of outer nozzle 7 and larger inner diameters of inner no~zle 6, both of which reduce the possibility of plugging o~ the coaxial nozzles when in use. These features are particularly -advantageous w~en the blowing gas contai.ns dispersed metal particles and/or ~he metal compositions contain additive mat~rial particles.
The Figures 3a and 3b of the drawings illustrate another preferred embodimen~ of the invention in which the outer portion of the transverse jet 13 is flattened to form a generally rectangular or oval shaped orifice opening l~a. The orifice opening .

13a can be dlsposed at an angle relative to a line drawn ~hrough ~he central axis of coaxial nozzle 5.
The preferred angle, however, is that as illu~rated in the drawing. That is, at an angle of about 90 to the central axis of the coaxial nozzle 5.
The use of the flattened transverse jet entrain-ing ~luid was fol~d, at a given ~elocity, to concentrate the effect of the fluctua~ing pressure ~ield an~ to increase the amplitude of the pressure fluctuations induced in the region o~ the formation of the hollow microspheres at the opposite or lee side of the bl.owing nozzle 5. Bythe use of the flattened transverse jet and increasing the amplitude of the pressure fluctuations, _ the pinching a~tion exerted on the cylinder 12 is increased.
This action facilitates the closing off of the cylinder 12 at its inner pinched end 16 and detaching o~ the cylinder 13 ~rom the orifice 7a of the o-~ter- nozzle 7.
The Figure 3c of the drawings illus~rates another preferred embodiment of the present invention in which a high viscosity film forming metzl material i5 used to blow h~llow metal filamented microspheres. In this Figure, the elongated shaped cylinder 12 and metal microspheres 17a, 17b and 17c are connected to each other by thin metal ~ilaments 17d. As can be seen in the drawing, as the microspheres 17a, 17b and 17c progress away ~rom blowing nozzle S surface tension forces act on the elongated cylinder 12 to effect the gradual change of the elongated shaped cylinder 12 to the generally spherical shape 17a, more spherical shape 17b and finally the spherical shap~ microsphere 17c. The same surface tension ~orces cause a gradual reduction in the diameter of the connecting filaments 17d, as ~he distance between the microspheres and fi.laments and the blowing nozzle 5 increases. The hollow metal microspheres 17a, 17b and ,, .
17c ~ha~ are obtained are connected by thin ~ilamen~
portions 17d ~hat are substantially of equal length and that are continuous with the metal microsphere.
The operation of the apparatus illustra~ed in Figures 3, 3a, 3b and 3c ls similar to that discussed above with regard to Figures l and 2 of the drawings.
The Figure 4 of the drawings illustrates an embodiment of the invention in which the lower por-tion of the coaxial nozzle 7 is provided with a bulbous member 23 which imparts to the outer nozzle 7 a spherical shape. This embodiment as in ~he previous embodiments comprises coaxial blowing nozzle 5 which consists of inner nozzle 6 with orifice 6a and _ outer nozzle 7 with orifice 7a. The figure of the drawings also shows elongated cylinder shaped liquid film 12 with the pinched portion 16.
The use of the bulbous spherical shaped member 23 was found for a given velocity of entraining fluid 14 (Flgure 2) to .substantially increase the amplitude of 2Q the pressure fktctuations induced in the region of the , formation of the hollow microspheres at the opposite or lee side of the blowing nozzle 5. By the use of the bulbous member 23 and increasing the amplitude of the pressure fluctuations, the pinching action exerted on the elongated cylinder 12 is increased. This action facilitates the closing o~f of the cylinder 12 at its inner pinched end 16 and de~aching the cylinder 12 from the orifice 7a of the outer nozzle 7. When using a bulbous mem~er 23, the transverse jet 13 is aligned such that a line drawn through the center a~is of ~rans~erse jet 13 will pass ~hrough the center o bulbous member 23.
In still another embodiment of the invention which is al~o lllustrated in Figure 4 of the drawings, a beater bar 24 can be used to assist in detaching the cylinder 12 B~3 -2~-:
from orifice 7aO The beater bar 24 ls attached to a spindle, no~ shownr which is caused to rota~e in a manner sueh that the beater bar 24 i5 brough~ to bear upon the pinched portion 16 of the elongated cylinder 12 and to thus facilitate ~e closing off of the cylinder 12 at its inner pinched end 16 and detaching ~he cylinder 12 from the orifice 7a of outer nozzle 7. The beater bar 24 is set to spin at about the same rate as the formation of hollow microspheres and can be 2 to 1500, preferably 10 to 800 and more preferably 20 to 400 revolutions per second. The film forming metal material micro-spheres are formed at a rate of 2 to 1500, preferably 10 to 800 and more preferably 20 to 400 per second.
15 7 The operation of the apparatus illus~rated is otherwise similar to that disclosed above with regard to Figures 1, 2, 3 and 4.
The embodiments of the invention illustrated in the Figures 2 to 4 can be used singly or in various combinations as the. si~uation may require.
. The entire apparatus can be enclosed in a high pressure containment vessel, not shown, which allows the process to be carried out at elevated pressures.
The Figures 5 to 7 are d~s-cus.sed below with referenL~ e~ che Examples.

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i ., FILM FORMING METAL MATERIAL COMPOSITIONS
. _ . _ . ., ... . _ i The film forming metal material and metal compositions and particularly the metal glass compositions from which the hollow metal microspheres o the present invention are S made can be wldely varied to obtain the desired physical characteristics for heating, blowing, forming, cooling and hardening the microspheres and the desired weight, strength and gas permeability characteristics of the metal microspheres produced.
The metal compositions can be selected to have a low heat conductivity and sufficienl: strength when cooled and solidified to, when the microsphere contains a high vacuum, withstand atmospheric pressure. The molten metal composi--i tion forms hard microspheres which are capable of contact-ing adjacent microspheres without significant wear or deterioration at the points of contact and are resistant to deterioration from exposure to moisture, heat and/or weathering.
The constituents of the metal compositions can vary widely, depending on their intended use, and can include small amounts of naturally occuring impurities.

The constituents of the metal compositions can be selected and blended ~o have high resistance to corrosive gaseous materials, high resistance to gaseous chemlcal agents, high resistance to alkali and weather, low suscepti~ility to diffusion of gaseous materials into and out of the metal microspheres, and to be sub-stantially free of trapped gas bubbles or dissolved gases in the walls of the microspheres which can form bubbles and to have su~ficient strength when hardened and soli-d:Lied to support a subs~an~ial amount of weight and/or to withstand a subs~antial amount of pressure.
-The film formlng metal compositions are forr~ulated to have relatively high melting and Eluid ~low tempera-tures with a relatively narrow tempera~ure difference between the melting, i.e. fluid flow and hardening temperatures. The metal compositions are formulated such th~.t they have a high rate of viscosity increase with decreasing temperature so that the microsphere walls will solidify, harden and strengthen befor~ the blowing gas within the sphere decreases in volume and pressure a sufficient amount to cause the microsphere to collapse.
There may be added to the metal compositions chemical agents which afect the viscosity of the compositions in order tv obtain the desired viscosities 15i for blowing the microspheres.
The process and apparatus of the present invention can be used to blow microspheres from suitable film forming metal materials or compositions, for example, metal glass alloy compositions, having sufficient viscosity at the temperature at which the microspheres are blown to form a stable elongated cylinder shape of the metal material being blown and to subsequently be detached to form the spherical or spheroid shaped microspheres and on rapid cooling to form a hardened film.
The film forming metal materials of the present invention, e.g. the metal glass alloy compositions depending on the constituents of the compositions, the wall ~hickness of the microspheres and the quench or cooling rate can form polycrystalline, partially polycrystalline and partially amorphous solid walls and substantially or comple~ely amorphous solid walls.
The quench rates needed to obtain substantially or completely amorphous sol.ids are in the order of 104 to 106C. per second. The metal glass microspheres made from compositions which on rapid cooling form substantially amorphous solids are a preerred embodiment of the In~ention.
... .. ._ .. , , . . .... .. , . ... , .... . . . ... . . ..... .. , .. _ .. . _ ... ._.. __.~

The metals to be used to form ~he microspheres are selected and can be treated and/or mixed with other materials, e.g.
other metals t to adjust their viscosity and ~urface tension characteristics such tha~ at the desired blowing temperatures they form stable films and are ,; capable of forming hollow metal microspheres o the desired si~e and wall ~hickness.
To assis~ in the blowing and formation o~ the metal microspheres and to control the surace tension and viscosity of the spheres suitable surface active agents, such as colloidal particles of insolwble sub-stances and vlscosity stabilizers can be added to themetal composition as additivies.
In an embodiment of the present invention metal glass compositions are used as the film forming metal material. The term metal glass~es) as used herein is intended to mean the metal alloy materials and compo-sitions which on rapid cooling from a temperature above their liquidus temperature to below the~r glass temperature can form amorphous solids.
The term liquidus temperature as used herein is 30 ` defined as the temperature at which ~he liquid and crystal phases of a metal alloy composition can exist in equilibrium, that is ~he temperature at which the crys~alline phase can first appear when the liquid is cooled.

.. . . _ _ .

i ., The term glass temperature as used herein i~
defined as the temperature at which t.he configuration of the metal alloy atoms become frozen in an amorphous solid state.
To form metal(lic~ ~lass(es~ it is necessary to rapidly cool the molten metal alloy composition from a temperature of about or just above the liquidus temperature to or below the metal glass tempera-ture at a rate of 104 to lQ6C per second. Some metal glass or glassy metal alloys at temperatures of about their liquidus temperature can have viscosities of abou~
10 poises. At the glass temperatures, the metal gla~s alloy viscosities rapidly increase to about 1015 poises .
~- Materials that resist change in shape this strongly are rigid enough to be consi~ered solids, and are herein referred to as solids.
Thère are ~ wide variety of metal glass alloy compositions which can be used in accordance with the process and apparatus of ~he present invention to make hollow metal gl~ss microspheres. The metal glass alloys compositions have be~n broadly described as (~) metal~metalloid alloys (e.g. Fe80P13C7 and Fe80B20)*, (2) transition metal alloys (e.g. Cu60Zr~O and Ni60Nb40) and (3) simple metal alloys (e.g. Ca65A135 and Ca65Zu35).
The known metal glass alloy composi.tions include pr cious metal alloys (e.g. Pd80Si20)~ alkallne e~arth metal alloys (e.g. Ca70Mg30), rare earth metal alloys (e.g. La76Au24) and actinide metal alloys (e.g. U70Cr30).
. ~ There is a substantial amount of published literature and a substantial number of patents which disclose various metal glass alloy compositions which are capable oX forming partially, substantially or completely amorphous solids.
; ~-The numbers indica~e atomic percentO

3~5~

The Chen et al U.S. Patent 3,856,513 discloses metal glass alloy compositions which can form amorphous solids. The disclosed compositions can contain (a) 75 to 80 atomic percent of iron, nickel, chromium, cobalt, or vanadium, and mixtures thereof, (b) 19 to 22 atomic percent of phosphorous, carbon and boron and mixtures thereof, and (c) 1 to 3 atomic percent of aluminum, antimony, beryllium, germanium, indium, tin and silicon, and mixtures thereof.
The Masumoto et al U.S. Patent 3,986,867 discloses metal glass alloy compositions which form amorphous alloys which have high heat resistance, high corrosion resistance and excellent mechanical properties. The alloy compositions disclosed contain (a) 1 to 40 atomic percent of chromium, (b) 7 to 35 atomic percent of at least one of carbon, boron, and phosphorous and (c) the remainder iron.
The Ray et al U.S. Patent 4,366,638 discloses binary amorphous alloy compositions of iron or cobalt and boron which have high mechanical hardness and soft magnetic properties.
These alloys contain (a) 75 to 85 atomic percent iron or cobalt and (b) 15 to 25 atomic percent boron.
The Ray U.S. Patent Nos. 4,210,443 and 4,221,592 also disclose metal glass alloy compositions which form amorphous solids.
It is to be understood that some metal glass alloy compositions are better glass formers, i~e. capable of forming amorphous solids, than others. The better alloy compositions can be obtained as amorphous solids, i.e. in the amorphous state, at lower cooling rates and/or microspheres can be obtained with relatively thicker walls when quenched from the molten liquid phase.

~30 The metal glass alloy compos~tions tha~ are capable, when rapidly quenc~ed, of forming hollow 7' microspheres or microspheroids are intended to come within the scope of the present invention.
The metal compositions from which the hollow metal microspheres can be made may, depending on the particular metal materials used, to some degree, be permeable to the gas materials used to blow the mierospheres and/or to the gases present in the medium surrounding the microspheres. The gas per-meabillty of the m~tal compositions can be controlled, modified and/or reduced or substantially eliminated by the addition, prior to blowing the microspheres, to the metal composition of ~ery small inert laminar plane-orientable additive material particles. I~en any one or more of these laminar plane-orientable additi~e material particles are added to a metal co~position prior to the blowing and formation of the hollow metal microsphere, the process of making the microsphere aligns the laminar particles, as the metal ,; film is stretched in passlng, i.e. extruded, through the conical blowing nozzle, with the walls of the hollow metal microsphere and normal to the gas diffu-sion direction. The presence cf the laminar plane particles in the microsphere walls substantially diminishes the gas permeabillty of the metal film. The 6izes of the additive particles are advantageously selected to be less than one-half the thickness of the wall of the microspheres.

~3 BLOWING GAS
The hollow microspheres and particularly the metal glass microspheres can be blown with a gas, an inert gas, an inert metal vapor or gas containing dispersed metal particles or mixtures thereof.
The inert gases used to blow the microspheres can be selected to have a low heat conductivity and involve heavy molecules which do no~ transfer h~at readily. Suitable blowing gases are argon, xenon, carbon dioxide, nitrogen, nitrogen dioxide, sulfur and sulfur dioxide. Organo metal compounds can also be used as a blowing gas. The blowing gas is selected to have the desired internal pressure when cooled to ambient temperatures. When sulfur, for example, is 'used as a blowing gas, the sulfur condenses and a partial vacuum can be formed in the microsphere~
Blowing gases can also be selected that react with or form an alloy with the metal film forming material or composition, e.g. the metal glass micro-spheres, for example, to assist in the hardening of the ;microspheres or to make the microsphere less permeableto the contained blowing gases. The blowing gases can also be selected to react or form an alloy with the deposited thin metal layer to obtain desired characteristics in the deposited metal layer. For certain uses, oxygen or air can be used as or added to the blow-ing gas~
The metal vapor is used as a blowing gas to obtain a substantial vacuum in ~he contained volume of the microsphere and to deposit a thin me.tal coating on the inner wall surface of the hollow metal microsphere.
The specific metal used as well as the ~hickness and nature of metal coating deposited will determine the properties of the deposited metal.

. . .. ~

~l~U~3 Small amounts of other metal vapors, e.g. alkali metals, that act as gettering materials can be added to the metal vapor blowing gas~ The gettering materials react with gases evolved from the molten metal film during the formation of the microspheres and maintain ~he hard contained vacuum.
The metal vapor blowing gases such as zinc, antimony, barium, cadmium, cesium, bismuth, selenium, lithium, magnesium, and potassium can be used. Zinc and selenium, however, are preferred and zinc is particularly preferred.
An auxilliary blowing gas, e.g. an inert blowing gas can advantageously be used in combination with a metal vapor blowing gas to assist in the control of the cooling and solidification of the hollow molten metal microsphere.
A blowing gas containing dispersed metal particles can be used to obtain in the contained volume of the microsphere a deposit of a thin metal coating on the inner wall surface o~ the hollow metal microsphere.
The metal used to coat the inner wall surface of the hollow metal microspheres is selected to have the desired characteristics and to adhere to the inner wall surface of the metal microspheresO The thickness of the deposited metal coating will depend to some extent upon the metal, the particle size of the metal used, the size of the microspheres and the amount of dispersed metal particles used.
The dispersed metal particle size can be 25A to lO,OOOA, preferably 50A to 5,000A and more preferable lOOA to l,OOOA.
A sufficient amount of the metal is dispersed in the blowing gas to obtain the desired thickness of the deposited metal.
The dispersed metal particles can advantageously be provided with an electrostatic charge to assist in depositing them on the inner wall surface of the microspheres.

V~5'~

,, Metal particles such as aluminum, ~ilver, nickel, i zinc, antimony, barium, cadmium, cesium, bisrnu~h, selenium, lithium, magnesium, potassium, and gold can be used. Aluminum, zinc and nickel, however, are preferred, Dispersed metal oxide particles can in a similar manner be used to obtain similar eXfects to that of the dispersed metal particles.
The thin metal coating can also be deposited on the inner wall surface of the microsphere by using as or with blowing gas organo metal compounds that are gases at the blowing temperatures. O the organo metal compounds available, ~he organo carbonyl compounds are preferred. Suitable organo me~al carbonyl compounds O, are nickel and iron.
1~ The organo metal cornpounds can be decomposed by heating just prior to blowing the microspheres to ob-tain finely dispersed ~etal particles and a decomposition gas. The decomposition gas, if present, can be used to assist in blowing the microspheres. The dispersed meta-particles rom decomposition of the organo metal compound, as before, deposit to form the thin metal layer. Alter-na~ively, the microsphere, a~ter being formed and con-taining the gaseous organo metal compound blowing gas, can be subjected to an "electric discharge" means which decomposes the organo metal compound to form the finely dispersed metal particles and the decomposi~ion gas.
The thickness of the deposited metal layer will depend primarily on the partial pressure of the gaseous organo metal blowing gas and the inside diameter o~ khe microsphere.
An auxiliary blowing gas can be used to dilute the gaseous organo metal compound blowing gas in order to control the thickness of the deposited metal layer.
There can also be used as an auxiliary blowing gas, a ~as tha~ acts as a catalyst for ~he decomposition of .. ... _ , _ .. ., .. , _ . _ . . . _ _, , . __ .

v~
. -34-. ~
the organo metal compound or as a hardenin8 agent ~or the film ~orming metal composl~ions. I~e addition of t the catalyst or hardening agent to the blowing gas prevents contact of the'catalyst with the organo metal compound or the hardening agent with the metal composition until a time just before the microsphere is ormed.
T~e blowing g~s or met'al ~apor blo~ng ~as can be selected to react w~th'and/or form an alloy with the ..
inner wall surface'of the micr'osphere.' The blowing gas reacting wIth'and/or the'forming of an alloy on the inner wall sur~ace' of the microsp~ere 'as it is being blown and formed can to some'extent help to stabilize ~aga~nst break_up~ the film ~orming metal material used to form the microsp~ere wall and allow sufficient time for the microsphere to form and harden.
A distinct and advantageous eature of the present i~vention is ~hat latent sol;d or latent liquid blowing gases are'not used or required and that the microspheres that are ,produce'~are free of laten~ solid or latent liquid ~ blowing gas materials or gases~

55~

.
THE EWTR~}WIN~ FLUID l The entraining ~luid can be a ga~ a~ a high or low ~emperature and can be selected to react with or be inert to the metal composition. The entraining fluid, e.g. an i.nert entraining ~luid, can be a high temperature gas. Suitable entraining fluids are nitrogen, air, steam and argon.
An important fea~ure of ~he present inventi.on i5 the use of the transverse jet to direct the inert entraining fluid over and around the coaxial blowing nozzle. The entraining fluid assi~ts in khe forma~ion and detaching of the hollow mo~ten metal microsphere from the cs~xial blowing nozzle.

THE Q~ENCH FLUID
The quench fluid can be a liquid, a liquid disper-sion or a gas. Suitable quench fluids are water, a ~ine water spray, bri~e, air, ni~rogen, or liquid nitrogen, helium or argon gases.
The inert quench fluid can also be ethylene glycol vapor or dispersion. The hollow molten metal microspheres immediately after ~hey are formed are rapidly quenched and cooled to solidy, harden and s~rengthen the metal microspheres before the internal gas pressure is reduced to such a low value that the microsphere collapses. The selection o a specific quench fluid and quench tempera-ture depends to some extent on the film forming metal composition from which ~he microsphere was formed and on the blowing gas or metal vapor used to bl~w the micro-~phere and on the metal and na~ure o~ the deposited metal ilm desired.

~36-O~SI. co/mrll~Ns The film ~ormi~g metal materials and~or composi tions of the present inven~ion are heated to a tempera ture a~ which ~hey are molten, e.g. above their liquidus temperature ~nd maintained in a liquid, fluid form during the blowing operation.
Many of the known metal glass alloy compositions have liquidus temperatures within the range o~ 900 to 1200C. and glass temperatures within the range of 0 300 ko 5005. depending on the constituents of the compositions.
The film forming metal compositions at temperatures at which they are molten, e.g. above their liquidus temperatures are fluid and 1OWS easil~ The molten 15j film forming metal composition, however, just prior to the blowing operation, i.e. just ~efore beginning of the ~orma~ion of the microsphere, can have a viscosity o 10 to 600 poises, preferably 20 to 350, and more preferably 3n to 200 poises.
Where the process is used to m~ke non-filamented microspheres, the liquld ~ilm forming metal composition just prior to the blowing operation can have a viscosity o~ 10 to 200 poises, preferably 20 to 100 poises, and more preferably 25 to 75 poises.
ZS Where the process is used to make ~ilamented microspheres, the liquid film forming metal composition just pr~or to the blowing operation can have a visc05ity of 50 to 600 poises, preferably 100 to 400 poises, and more preferably 150 to 300 poises.

A feature o~ the pr~sent invention is that the formation of the hollow metal microspheres can be carried out at low viscosities. Because of the ability to utiliæe comparatively low viscosities~ applicant i8 ab~.e to obtain hollow metal microspheres, the wall of which are free of any entrapped or dissolved gases or bubbles. Wikh the low viscosities used by applicant, any entrapped or dissolved gases diffuse.out and escape from the metal film surface during the bubble formation.
The molten or liquid metal fed to ~he coaxial blowing nozzle can be at about ambient pressure or can be at an elevated pressure. The molten or liquid metal feed can be at a pressure of 1 to 20,000 p.s.i.g., usually 3 to 10, 000 p . s . i . g . and more usually 5 to 5, 000 15 ~ip.s.i.g. The molten metal feed when used for low pressure application~ can be at a pressure of 1 to 1000 p.s.i.g., preerably 3 to 500 p.s.i.g. and more preferably 5 to 100 p.s.i.g.
Where the process is used to make microspheres for use in syntactic foam systems, the liquid metal fed to .the coaxial blowing nozzle can be at a pressure of 1 to 1, 000 p. s . i. g., preferably at 3 to 100 p . s . i . g., and more preferably at S to 50 p.s.i.g.
The molten film forming metal composition is con-tinuously fed to the coaxial blowing nozzle during theblowing operation to prevent premature breaking and detaching of the elongated cylinder.shaped molten metal liquid film as it is being formed by the blowing gas.
The blowing gas, inert blowing gas, gaseous material .blowing gas or metal vapor blowing gas will be at about the same temperature a3 the molten metal being blown.
The blowing gas temperature can, however, be at a higher temperature than the molten metal ~o assist in main~ain-. ing the ~luidity of the hbllow molten metal microsphere during the blowing operation or can be at a lower tempera-;ture than the mol~en glass to assist in the solidification 1 ., and hardening o~ the hollow molten metal microsphere as it is formed. The pressure of the blowing gas is sufficient to blow the'microsphere and will be slightly above'~he pressure of molten me~al a~ the orifice 7a o the'outer nozzle 7. The blowing gas pressure will also depend on and be slightly above the ambient pressure external to the blowing nozzle.
The temperatures of the blowing gases will depend on the blowing gas used and the viscosi~y-temperature-10 , shear relationship of the film forming metal materialsused to make the microspheres.
The metal vapor blowing gas temperature will be sufficient to vaporize the metal and will be at about _ the same temperature as the molten metal composition being blown. The metal vapor blowing gas temperature can, however, be at a higher temperature than the molten metal to assist in maintaining ~he fluidity of the hollow molten metal microsphere during the blowing operation or can be at a lower temperature than the mol~en metal to assist in the solidification an~ hardening of the hollow .; molten metal microsphere as it is formed. The pressure of the metal vapor blowing gas is sufficient to blow the microsphere and will be slightly above the pressure of molten metal at t'he orifice 7a of the outer nozzle 7.
The metal vapor blowing gas pressure will also depend on and be slightly above the am~ient pressure external to the blowing nozzle.
The pressure of the blowing gas or gaseous materia'l blowing gas, including the metal vapor blowing gas, is sufficient to blow the microsphere and will be slightly above the pressure of liquid metal a~ the orifice 7a of the outer nozzle 7. Depending on the gaseous material to be encapsulated within the hollow metal microspheres, the blowing gas or the gaseous ma~erial can be at a pressure of 1 to ~0,000 p.s,i,g., usually 3 to 10,000 p.s.i.g. and more usually 5 to S,000 p.s.i.g.

3~ 5 The blowing gas o~ gaseous material blowing gas can also be at a pressure of 1 to 1,000 p.s.i.g., preferably 3 to 500 p.s.i.g. and more preferably 5 to ~0~ p.s.i.g.
, Where the process is used to make microspheres for use as structural materials and in structural systems, for use in syntactic foam systems and as ~iller materials in general, the blowing gas or gaseous material blowing gas can be at a pressure of 1 to 1,000 p.s.~.g., preferably at 3 to 100 p.s,i.g. and more preferably at 5 to 50 p.s.i.g.
The pressure of the blowing gas containing dispersed metal particles alone and/or in combination with the ~ principal blowing gas is sufficient to blow the micro sphere and the combined gas pressure will be slightly above the pressure of the liquid film forming metal composition at the orifice 7a o the outer nozæle 7. The pressure o the combined mixture of ~he blowing gases will also depend on and be slightly above the ambient pressure external to the blowing nozzle.
The ambient pressure external to the blowing nozzle can be at about atmospheric pressure or can at at sub~
atmospheric or super-atmospheric pressure. Where it is desired to have a relatively or high pressure of contained 25 gas in the microsphere or to deposit a relatively thick coating of metal within a vacuum microsphere, the ambient pressure external ~o the blowing nozzle is maintained at a super-atmospheric pressure. The ambient pressure ex-ternal to the b].owing nozzle will, in any event, be such that it substantially balances, but is slightly less than the blowing gas pressure.
The transverse jet inert entraining fluid which is directed over and around the coaxial blowing nozzle ~o assiqt in the ormation and detaching o the hollow molten metal microsphere from the coaxial blowing no7.zle cah be at abo~t ~he temperature of the molten metal being blown. The entraining fluid can, however, be at a higher temperature than the molten metal to assist in maintaining the fluidity of the hollow molten metal microsphere during the blowing operation or can be at a lower temperature than the molten glass to assist in the stabilization of the forming film and the solidification and hardening of the hollow molten metal microsphere as it is formed.
The transverse jet entraining fluid which is directed over and around the coaxial blowing nozzle to assist in the formation and detaching of the hollow liquid metal microsphere from the coaxial blowing nozzle can have a linear velocity in the region of microsphere formation of 1 to 1~0 ft/sec, usually 5 to 80 ft/sec and more usually 10 to 60 ft/sec.
Where the process is used to make non-filamented microspheres, the linear velocity of the transverse jet fluid in the region of microsphere formation can be 30 to 120 ft/sec, preferably 40 to 100 ft/sec and more preferably 50 to 80 ft/sec.
Where the process is used to make filamented microspheres, the linear velocity of the transverse jet fluid in the region of microsphere formation can be 1 to 50 ft/sec, preferably 5 to 40 ft/sec and more preferably 10 to 30 ft/sec.
Further, it is found (Figures 2 to 4) that pulsing the transverse jet entraining 1uid at a rate of 2 to 1500 pulses/sec, preferably 50 to 1000 pulses/sec and more preferably 100 to 500 pulses/sec assist in controlling the diameter of the microspheres and the length of the filament portion of the filamented microspheres and detaching the microspheres from the coaxial blowing nozzleO
The distance between filamented microspheres depends to some extent on the viscosity of the metal and the linear velocity of the transverse jet entrainin~ fluid.
The entrainin~ fluid can be at the same temperature as the liquid metal being blown. The entraining fluid can, ......
..~!;. .~J

B5~3 however, be at a higher temperature than the liquid me-tal to assist in maintaining the fluidity of the hollow liquid metal microsphere during the blowing operation or can be at a lower temperature than the liquid metal to assist in the stabilization of the forming film and the solidification and hardening of the hollow liquid metal microsphere as it is formed.
The quench fluid is at a temperature such that it rapidly cools the hollow molten metal microsphere to solidify, harden and strengthen the molten metal before the inner gas pressure or metal vapor pressure decreases to a value at which the metal microsphere would collapse. The quench fluid can be at a temperature of 0 to 200 F., preferably 40 to 200 F.
and more preferably 50 to 100F. depending to some extent on the composition of the film forming metal composition to be cooled.
Where aqueous brine or ethylene glycol dispersions are used, quench temperatures of -60C. and -50C., respectively, can be obtained.
Where vexy rapid or high cooling rates are desired, cryogenic fluids such as liquid nitrogen, helium or argon can be used.
Where cryogenic fluids are used to cool the microspheres, temperatures as low as -195C. for nitrogen, -268C. for helium, and -185C. for argon can be obtained in the vicinity of the microspheres by use of dispersed sprays of the cryogenic fluids.
The quench fluid very rapidly cools the outer molten metal surface of the microsphere with which it is in contact and more slowly cools the blowing gas or metal vapor enclosed within the microsphere because of the lower thermal conductivity of the contained blowing-~as or ,", ,~, ~3 met'al vapor. This cooling process allows sufficient t~me'for ~he` ~etal wall~ of ~he microspheres to strengthen be~ore'the gas is' cooled or the metal vapor is co'oled and condensed and a high vacuum formed within the metal microsphere.' Where a met'al vapor blowing gas ~s used, hard ~acuums o~ 10 4 to 10 6 Torr can be'obtained in the contained volume'o the microsphere.' The'time'elapsed from commencement of the blowing , 10 a~ the metal microspheres' to the'cooling and hardening o the microspheres' can be .0001 to l.0 second, pre-ferably .0010 ~v 0.50 second and more preferably O.O:L0 to 0.10 second. Suita~le'cooling rates are of the order , o~ 104 to 106C., per second, i.e.' aBout 1.8x104 to lS 1.8x10~~,. per second. I~en cooling the metal glass compositions of the pres'ent invention to obtain amorphous met'al microspheres' cooling rates' of 104 to 106C. per second are preferred. The quench rate required will to some extent depend on the wall thickness of the microsphere.
~, The'filamented microsphere embodiment of the inven-tion prov~des a means b~ w~ich the microspheres may be suspended and allowed to harden and strengthen without being brought into contact with any surface. The fila-mented microspheres are'simply drawn on a blanket ordrum and are suspended between the blowing nozzle ancl the blanket or drum for a sufficient period of time l.'or them to harden and strengthen. This procedure can be used where desired ~o form oblate spheroid shaped microspheres.

S~5~3 APPARATUS
Referring to Figures 1 and 2 of the drawings, the refractory vessel 1 is constructed to maintain the molten film forming metal material at the desired operating temperatures.
The molten film forming metal material 2 is fed to coaxial blowing nozzle 5. The coaxial blowing nozzle 5 consists of an inner nozzle 6 having an outside diameter of 0.32 to 0.010 inch, preferably 0.20 to 0.015 inch and more preferably 0.10 to 0.020 inch and an outer nozzle 7 having an inside diarlleter of 0.420 to 0.020 inch, preferably 0.260 to 0.025 and more preferably 0.130 to 0.030 inch. The inner nozzle 6 and outer nozzle 7 form annular space 8 which provides a flow pa~h through which the molten glass 2 is extruded. The distance between the inner nozzle 6 and outer nozzle 7 can be 0.050 to 0.004, preferably 0.030 to 0.005 and more preferably 0.015 to 0.008 inch.
The orifice 6a of inner nozzle 6 terminates a short distance above the plane of orifice 7a of outer nozzle 7. The orifice 6a can bespaced above orifice 7a at a distance of 0.001 to 0.125 inch, preferably 0.002 to 0.050 inch and more preferably 0.003 to 0.025 inch. The molten film forming metal material 2 flows downwardly and is extruded through annular space 8 and fills the area between orifice 6a and 7a. The surface tension forces in the molten film forming metal material 2 form a thin liquid molten film forming metal material film 9 across orifice 6a and 7a which has about the same or a smaller thickness as the distance of orifice 6a is spaced above orifice 7a. The orifices 6a and 7a can be made from quartæ~ zirconia or fused alumina The surface tension forces in the liquid film forming metal material 2 form a thin liquid film forming metal materia~l film 9 across orifices 6a and 7a which has about the same or a smaller thickness as the distance of orifice , ..
..: . .~

~ 5 ; -44-6a is spaces above orifice 7a. The molten f~lm forming me~al material film 9 can be 25 to 3175 microns, pre-: ~ ferably S0 to 1~70 microns and more preferably 76 to 635 microns thick.
The Figure 2 blowing nozzle can be used to blow molten film forming metal material at relatively low viscosities, for example, of 10 to 60 poises, and to blow hollow film forming metal material microspheres of relatively thick wall siæe, for example, of 20 to 100 microns or more.
A blowing gas, inert blowing gas, gaseous material blowing gas or metal vapor blowing gas is fed through inner coaxial nozzle 6 and brought into contact with the inner surface of molten film forming metal material ~film ~. The inert blowing gas exerts a positive pressure on the molten metal material film to blow and distend the film outwardly and downwardly to form an elongated cylinder shaped liquid ilm 12 of molten film forming metal material filled with the blowing gas 10. The elongated cylinder 12 is closed at its outer end and :is s~nnec~ed to outer nozzle 7 at the pexipheral edge of orifice 7a.
The transverse jet 13 is used to direct an inert entraining fluid 14 through nozzle 13 and transverse jet nozzle orifice 13a at the coaxial blowing nozzle 5. l'he coaxial blowing nozzle 5 has an outer diameter of 0.52 to 0.030 inch, preferably 0.36 to 0.035 inch and more preferably ~.140 to 0.040 inch.
The process of ~he pres~nt invention was found to be very sensitive ~o the distance of the transverse jet 13 from the ori~ice 7a of outer nozzle 7, the angle at which the transverse jet was directed at coaxial blowing nozzle 5 and the poin~ at which a line dxawn through the center axis of transverse jet 13 intersected with a line ~5 drawn thr~ugh the center axis of coaxial nozzle 5. The transverse jet 13 i8 aligned to direct the ~low of entraining fluid 14 over and around ou~er nozæle 7 in the microsphere~ orming region of the orifice 7a.
The orlfice 13a o transverse jet 13 i8 loca~ed a distance of 0.5 to 14 times, preferably 1 to 10 times and more preferably 1. 5 to 8 times and still more preferably 1.5 to 4 times the outside diameter of coaxial blowing nozzle 5 away from the point of inter-sect af a line drawn along the center axis of trans verse jet 13 and a line drawn along the center axis of coaxial blowing nozzle 5. The center axis of trans-verse jet 13 is aligned at an angle oiE 15 to 85, prei~erably 25 to 75 and more pre~erably 35 to 55 relative to the center axis of the coaxial blowing 15 ~,.nozzle 5. The orifice 13a can be circular in shape and h~ve an inside diameter of 0.32 to 0.010 inch, prefer-ably 0.20 to O.OlS inch and more preferably 0.10 to 0.020 inch.
The line drawn through the center axis of transverse jet 13 intersects the line drawn ~hrough the center axis of coaxial blowing nozzle 5 at a point above the orifice 7a of outer nozzle 7 which is .5 to 4 times, preferably 1.0 to 3.5 times and more preferably 2 to 3 times the outside diameter of the coaxial blowing nozzle 5. The transverse jet entraining fluid acts on the elongated shaped cylinder 12 to flap and pinch it closed and to detach it from the orifice 7a of the outer nozzle 7 ~o allow the cylinder to fall i~ree, i.e. be transported laway from the outer nozzle 7 by the entraining fluid.
The transverse jet entraining fluid as it passes over and around thè blowing nozzle fluîd dynamically induces a periodic pulsa~ing or fluctuating pressure i.ield at the opposite or lee side o~ the blowing nozzle in t:he wake or shadow of the coaxial blowing nozzle~ A similar 35 periodic pulsa~ing or fluctuating pressure field can ,, ,,,,,,, ,. , .. , .. . .. ... . ..... .. . ., .. _ .. . . . . , . . ,, . . . .... , , .. _ . .. , .
.... _, . _ .... , ... _ ._ .

be produced by a pulsa~ing ~onic pressure field directed at the coaxial blowing noæzle. The entraining fluid assists in the ~ormation and detaching of the hollow film forming metal material microspheres from the coaxial blowing nozzle. The use of the transverse jet and entraining fluid in the manner described also dis-courages wetting of the outer wall surface of the coaxial blowing noæzle 5 by the molten ~ilm forming metal material being blown. The wet~ing of the outer wall disrup~s and in~erferes with blowing the micro~pheres.
The quench nozzles 18 are disposed below and on both sides of coaxial blowing nozzle 5 a sufficient distance apart to allow the microspheres 17 to fall between the ~uench nozzles 18. The inside diameter of quench nozzle orifice 18a can be 0.1 to 0.75 inch preferably 0.2 to 0.6 inch and more preferably 0.3 to 0.5 inch. The quench noæzles 18 direct cooling fluid 19 at and into contact with the molten film forming metal material microsphe:res 17 at a velocity of 2 to 14 preferably 3 to 10 and more preferably 4 to 8 ft/sec to rapidly cool and solidify the molten film forming metal material and form a hard smooth hollow film forming rnetal material microsphere.
The Figure 3 of the drawings illustrates a preferred embodiment of the invention. It was found that in blowing molten film forming metal material compositions at higrh viscosities that ît was advantageous to immediately prior to blowing the molten film forming metal material to pro-vide by extrusion a ~ery thin molten film forming metal material liquid film for blowing into the elongated cylinder shape liquid ilm 12. The thin molte!n film orming metal mat~rial liquid film 9l is provided by having the lower portion of the outer coaxial nozzle 7 tapere!d downwardly and inwardly at 21. The tapered portion 21 and inner wall surface 22 thereof ca~ be at an angle of 15 to t~

75,-.preerably 30 ~o 60 and more preerably about 45 relative to the center axis o~ coaxial blowing nozzle 5.
The orifice 7a' can be 0.10 to 1.5 time~, preferably 0.20 to 1.1 times and more preferably 0.25 to .8 times the inner di.ameter of orifice 6a of inner nozzle 6.
The thickness of the molten film forming metal material liquid film 9' can be varied by adjusting the distance of orifice 6a of inner nozzle 6 above orifice 7a of outer nozzle 7 such tha~ the distance between the peripheral edge of orifice 6a and the inner wall sur:Eace 22 of tapered nozzle 21 can be varied. By controlling the distance between the peripheral edge of orifice 6a and the inner wall surface 22 of the tapered nozzle to form a very fine gap and by controlling the pressure applled to feed the molten fllm forming metal ma~erial 2 through annular space 8 the molten film fo~ning metal material glass 2 can be squeezed or extruded through the very fine gap to form a relatively ~hin molten film forming metal material liquid film 9'.
The proper gap can best be determined by pressing 2C ~ the inner coaxial nozzle 6 downward with sufficient pres~ure to comple~ely block-off the flow of film form-ing metal material and to then very slowly raise the inner coaxial nozzle 6 until a stable system is obta:ined, i.e. until the microspheres are bei.ng formed.
The. tapered nozzle construction illus~rated in Figure 3 is as mentioned abowe ~he preferred embodiment of the invention. This embodimen~ can be used to ~low film forming metal n~Lterial compositions at relative].y high viscosities as well as to blow film forming metal material compositions at th~ relatively low vi~cositi.es referred to with regard to Figure 2 of the drawings.
The Figure 3 embodiment of the invention is of partic:ular advantage in blowing the thin walled microspheres..

When blowing high or low viscosi~y film foxmi metal material compositions, it was found to be advantageous to obtain the very thin molten me~al i.-luid film and to continue duri~g the blowing operation t:o ;
supply molten ~etal to ~he elongated cylinder shaped liquid film as it was formed. Where a high pressure is used to squeeze, i.e. extruded, the molten metal throu~h the very thin gap, the pressure of the inert blowing gas or metal vapor is generally less than t~e molten metal feed pressure, bu~ slightly abo~e the pressure of the molten metal at the coaxial blowing nozzle.
The tapered nozzle configuration of Figure 3 is also particularly useful in aligning the laminar plane-15~ orientable film forming metal material additive materials.
The passage of the metal material through the fine or narrow gap serves to align the additive materials with the walls of the microspheres as the microspheres a-re being formed.
The Figure 3 also shows an embodiment of the inven-tion in which a heating coil is pro~ided around the blow-ing nozzle The heating coil is high enough above the orifice 7a such that it does not interfere with blowing the microspheres, but low enough to provide accuratei temperature control of the molten film forming metal composition. The heat can be provi.ded by conduction or induction heating or radio frequency radiation methods The Figures 3a and 3b of the drawings also illustrate a preferred embodiment of the invention in which the transverse je~ 13 is flattened to form a generally rectangular or oval shape. The orifice 13a can also be flattened to form a generally oval or rectangular shape.
The width o ~he oxi~ice can be 0.96 to 0.030 inch, pre-erably 0.60 to 0.045 inch and more preferably 0.030 to 0.060 inch. The heigh~ of the oriice can be 0.32 t~

-4g-;
; 0.010 inch, preferably 0.20 to 0.015 inch and more preferably 0.10 to 0.020 inch. -With rePerence to Figure 3c o~ the drawings which illustrates an embodiment of the present invention ln which a high viscosity ~ilm forming metal materlal or composition is used to blow filamented hollow film forming metal material microspheres, there is shown the f~rmation of the uniform diameter microspheres spaced about equal distances apart. The numbered items in this drawing have the same meanings as discussed above with reference to Figures 1, 2, 3, 3a and 3b.

DESCRIPTION OF THE MICR~SPHE~S
15 o; - The hollow microspheres made in accordance with the present inven~ion can be made rom a wide variety o film forming metal materials and metal compositions, particularly metal glass compositions.
The hollow microspheres made in accordance with the present invention can be made from suitable film forming metal compositions. The compositions are preferably s~able at relatively high temperatures and resistant: to chemical attack, resistant to corrosive and alkali and resistant to weathering as the isituation may require.
The compositions that can be used are those that have the necessary viscosities, as mentioned above, when bein~ blown to orm stable films and which have a rapid change from the molten or liquid state to the solid or hard state wi~h a relatively narrow ~emperature change.
That is, they change from liquid to solid within a rela-tively narrowly defined temperature range.
The hollow metal microspheres made in accordance with the present invention are preferably made from a metal glass composition, they can be substantially uniform in diameter and wall thickness, have a hard, smooth s~

, surface and are stable at rel~tively high temperatures, resistant to chemical attack, weatherin~;and di~fusi.on of t gases into and/or out of the microspheres. The wall of the microspheres are free or substan~ially free o~ any holes, relatively thinned wall portions or sections, sealing tips, ~rapped gas bubbles, or sufficient amounts of dissolved gases to form bubbles. The microspheres are also free of any latent solid or liquid blowing gas materials or gases.
The microspheres, because the walls are substan-~ially free of any holes, thinned sections, trapped gas bubbles, and/or sufficient amounts of dissolved gases to form trapped bubbles, are substantially stronger than the microspheres heretofore produced. The absence of a sealing tip also makes the microsphere stronger.
To fc~rm metal glass alloy microspheres in which the walls of the microsp~eres are in the form of an amorphous solid, i.e. in the amorphous state, the molten metal glass composition must be cooled rapidl~ from a temperaturle above its llquidus temperature to a temperature ~elow its glass tempera~ure, D~pending on the composition of the metal glass alloy used,the thickness of the wall of the microsphere and the cooling rate, in some instances the microspheres may not have suficient time to pe~nit sur~ace tension forces to form the microsphere into a spherical shape. In some situations a microspheroid having an oblate shape, i.e. an elongated shape may be formed. The term microsphere as used here~n is intended to include spherical as well as spheroid shaped micro-spheres. The important feature of the process of thepresent invention is ~hat under a specified set of operating conditions each microsphere as it is for~ed is of substantially the same size and shape as the preceding and following microspheres. The formation of spheroid shaped microspheres can also occur when rapid cooling and forming polycrystalline or partially polycry~talli.ne metal ~ilm orming material microspheres, e.g. ~rcm metal glass alloy composi~ions.
The term filamented microspheres includes micro spheres connected by continuous ilarnents as well as microspheres which have been massed toge~her and have had some or a major portion of the connect~ng filaments broken.

\, `\\\

~ -52-?j The metal miorospheres can be made in various diameters and wall thickness, depending upon the desired end use of the microspheres. ~le mierospheres can have an outer diameter of 200 to 10, 000 microns, S preferably 500 to 6,000 microns and more preferably 1,000 to 4,000 microns. The microspheres can have a wall thickness of 0.1 to 1,000 microns, preferably 0.5 to 400 microns and more preferably 1 ~o 100 microns.
The microspheres can contain an inert gas at super-atmospheric pressure, about ambient pressur~e or a partial vacuum in the elongated volume. The pa:ctial vacuum can be obtained by us;ng a blowing gas which partially condenses within the microsphere.
The microspheres can contain a high vacuum iTI
15 ' the enclosed volume where a metal vapor is used as a blowin~ gas and the metal vapor is eooled, condenses and deposits as a thin metal coating on the inner wall surface of the hollow microsphere. The pressure in the m;crosphere will be equal to the vapor pressure of the deposited metal at ambient temperature.
The thickness of the thîn deposited metal vapor coating deposited on the inner wall surface of the microsphere will depend on the metal vapor used to blow the microsphere, the pressure of the metal vapor and the size of the microsphere. The thickness of the thin metal coating can be 25 to lOOOA, preferably 5~0 to 600A, and more preferably 100 to 400A.
The diameter and wall thickness of the hollow microspheres will of course affect the average bulk density 30 of the microspheres. The metal microspheres prepared in accordance with the invention will h~ve an ave age bulk~
density of 1 to i~ lb/ft ~ preferably 1.5 to ~ lb/ft3 /'' and more preferably 2 to ~L lb/ft3. For use in specific ~ ~, embodiments to m~ke low density m~terials, the hollow 35 ~etal mi~rospheres can have an average bulk density as low~as 0.5 to 1.5, for example 1.0 lb/ft3.

S~
. -S3~
,~

Where the microspheres are formed i~ a manner such tha~ they are connected by con~inuou~ ~hln met:al filaments, that is ~hey are made in ~he form o filamented microspheres, the length o~ the connecti.ng filaments can be 1 to 40, usually 2 to 20 and more usually 3 to 15 times the diameter of the micro-spheres. The diameter, tha~ is the thickness o the connecting filaments, can be 1/5000 to 1/10, usually 1/2500 to 1/20 and more usually 1/1000 to l/30 9f the diameter of the mic`rospheres The microspheres can contain a gas at super-atmospheric pressure, about ambient pressure vr at partial or hard, i.e. high, vacuum, 2. g. 10 4 to 10 5 Torr.
~. Where the microspheres are used in syntactic foam systems, or as ~iller material in general, the microspheres can have an ou~er diameter of 500 to 3,000 and can have a wall thickness o 0.5 to 200 microns. When used in syntatic foam systems and as filler material~, the microspheres can have a conta:ined gaæ pre~sure of 5 to 100 p.s.i.a., preferably 5 to 75 p.s.i.a. and more preferably 5 to 12 p.s.i.a.
In a preferred embodiment of the in~ent.ion, the ratio of the diameter to the wall thickness of the microspheres is selected such ~hat ~he microspheres are flexible, i.e. can be deformed under pressure with-~ut breaking The microspheres can con~ain a ~hin metal layer deposited on the inner wall surface of the microsphere where the blowing gas contains dispersed metal particles.
` The thickness of the thin metal coating deposited on.
the inner wa~l surface of the microsphere will depen.d on the amount and particle ~ize of the dispersed metal particles or partial ~ressure of organo metal blowing gas that are used and the diameter of ~.he microsphere.
The thickness of the thin metal coa~ing can be Z5 to s~

O O
lO,OOOA, preferably 50 to 5,000A and more pre~erably 100 to 1,0~0~.
t The strength and thermal hea~ eonductivity character-istics of heat barrlers made from ~he rnicrospheres can be improved by partially flattening the microspheres into an oblate spheroid shape. The strength and t:hermal conductivity characteristics of the oblate spheroids is further improved by mixing with the oblate spheroids thin metal filaments. The filaments are pre~erably provided in the form of the filamented microspheres.
The filamented microspheres can as they are i.ormed be drawn and laid on a conveyor belt or drum. A sufficient amount of ension can be maintained on ~he filamerlted microspheres as they are formed and drawn ~o stretch them into ~he oblate spheroid shape. The filamented micro-spheres are maintained in that shape for a sufficient period of time to harden. After hardening of the filamented oblate spheroids, they can be laid in a bed and cemented together by sintering or fusion or bonding Z0 and can be ma~e into structural forms, e.g. a four by ; eight-foot ~onned panel. The panel can be 1/4 to 3 inches, for example, 1/~, 1, 1 1/2 or ~ inches, in thickness.
The hollow metal microspheres of the present inven-tion have a distinct advantage o being very strong and capable of support D ng a substantial amount of weight.
They can thus be used to make a simple light weight, strong, inexpensive self-supporting or load bearing struetures and systems.
The hollow metal microspheres of the present invention ran be used to design ~ystems having superior strength to wei.ght characteristics.
A mass of the microspheres or filamented micro-spheres can be cemented or bonded together to form a shaped form or formed ma~s of the microspheres. The shaped form or formed mass of the microspheres can be v~3 .
! cemented together by fusion or sintering or bonded together with an organic or inorganic bonding agent or adhesive.
The microspheres can be made into sheets or other shaped forms by cementing the microspheres together with a suitable resin or other adhe~ive or by fus;ing the microspheres together and can be used in new construction.
A formed panel or sheet can be made from several layers of hollow metal microspheres bonded together with a polyester, polyolefin, polyacrylate or polymethyl acrylate resin. The microspheres may also be bonded together with inorganic bonding agents, such as O~ENS-CORNING solder glass and solder glass-organic solvent or carrier ~ystems.
The interstices between the microspheres can be filled with smaller microspheres of the present invention, ~inely di~ided inert particles, or ~oam, e.g. of polyure-thane, polyester or polyolefin resin ~oam.
The hollow metal microspheres may be formed into shaped forms, sheets or panels by ta~in~ ~he microspheres directly after they are formed, while still hot an~d pressin~ them under pressure into the desired shap~e. The still hot microspheres when compressed under pres~ure 2S to some extent are sintered or fused together.
Metal microspheres having selecti~e permeability to certain gases or liquids can be rnade by proper selectlon of the cons~ituents of ~he film forming metal composition. The amount of a specific metal can be added to the metal composition. The specific meta;L is selected to be one that can be selecti~ely chemically leached from the metal microsphere. The amount of the selected metal a~d the degree o~ chemical leaching will determine to ~ome extent the permeability or pour ~ize of the resulting me~al microsphere. A sopper and silver metal glass alloy may9 ~or example, be selectively leached with hydroc~loric acid to selectively remove some of the copper in the copper and silver metal glass alloy. Hollow me~al microspheres can accordingly be produced 5 and used to make or act as selective absorption membranes, e.g. to act as molecular sleves.

.. \

)85 ~XAMPLES
Exa~ple 1 A film fo~ming metal material eompo6ition i8 used to make ~bllow metal microsp~eres.
The metal composition is heated ~o a :
su~ficiently high temperature to form a fluid mol~en metal. The molten metal ~ust prior to the blowing operation, i.e. ~ust before the beginning of the blowing o the m~crosphere can have a viscosity of 35 to 60 poises.
The molten metal is fed to the appara~us of Figures 1 and 2 of the drawings. The molten metal passes through annular space 8 of blowing nozzle 5 and forms a thin liquid molten metal film across the orifices 6a and 7a. The blowing nozzle 5 has an outside diameter of 0.040 inch and oriice 7a has an inside diameter o~ 0.030 inch. The thin liquicl molten ~etal film ha~ a diameter of 0.030 inch and a thickness of 0.005 inch. An inert blowing gas consisting o~ xenon or n~trogen at about the temperature of the molten metal and at a positive pressure is applied to the inner surface of the mol~en metal film causing the film to distend downwardly into a elongated cylinder shape with it~ outer end closed and its inner end attached to the outer edge of orifice 7a.
The transverse jet is used to direct an inert:
entraining fluid which consists of nitrogen at abc>ut the temperature o~ the molten metal over and around the blowing nozzle 5 which entraining fluid assists in the formation and closing of the elongated cylinder ~hape and the detaching of ~he cylin~er from ~he blowing nozzle and causing the eylinder to fall ~ee of the blowing nozzle. The ~xa~sverse ~et is ali~ed at an angle o~ 35 ~o 50 rela~ive to the blowing nozzle ~,35 and a line drawn t~rough ~he center axis of the trans-ve~e ~et intersects a line drawn through the center . -58~
`1 axis of the blowing nozzle 5 at a po;n~ 2 ~o 3 times the outside diameter of ~he coaxial blowing nozzle 5 above the orifice 7a.
The free ~alling, i.e. entrained, elongated cylinders quickly assume a spherical shape and are rapidly cooled to about ambient temperature by a dispersion of ~uench fluid at a temperature of -60 to -100C~ which quickly cools, solidifies and hardens the metal microsphere.
-Clc~ ~mooth,~hollow metal microspheres having a 2000 to 3000 micron diameter, a 20 to 40 micron wall t~ickness and fi.lled with xenon or nitrogen gas at an înternal containea pressure of 3 p.s.i a. are obtained.
The metal microspheres are suitable for use as fi.ller materials.

xample 2 A film forming metal material compositîon is used to make hollow metal vacuum microspheres.
The metal comp~sition is heated to a sufficiently high temperature to form a fluid molten metal. The 2p molten metal ~ust pr;or to the blowing operation can have a viscosity of 35 to 6~ poises.
The molten metal ~s ~ed to the apparatus of Figures 1 and 3 of the drawing~. The molten metal is passed through annul2Lr space 8 of blowing no~zle 5 and into tapered portion 21 o~ ou~er nozzle 7. The molten metal under pressure is squeezed through a fine gap ~ormed between ~he ou~er edge of ori1ce 6a and the inner surface 22 of the tapered portion 21 o~ outer nozzle 7 and forms a thin liquid molten metal fil~m across the orifices 6a and 7a'. The blowing nozzle 5 has an outside diame~er of 0.05 inc~ and orifice 7a' has an inside diame.ter o~ 0.03 inch. The thin lâquid molten metal film has a diameter of 0.03 inch ` and a thickness o 0.01 i~ch. A zinc vapor blowin,g gas at about.the same temperature as the molten m~etal 5~ .

and at a po3i~ive pressure i~ applied to the inr~er su~face of the molten metal film c~using the film to distend outwardly into an elongated cylinder shape with its outer end closed and its inner end attached to the outex edge of orifice 7a'.
! The transverse jet is used to direct an inert entraining fluid which consists of nitrogen gas at about the same temperature as the molten metal at a linear velocity of 40 to 100 feet a second over and around the blowing nozzle 5 which entraining fluid assists in the 'formation and closing o~ the elongated cylindex shape and the detaching of the cylinder from the blowing nozzl'e'and causing the cylinder to fall free of the blowin~ nozzle. The transverse jet is 1~ aligned relative- ~o the blowing nozzle as in E~ample 1.
The free falling elonga~ed cylinders filled with the zinc vapor'quickly assume a sherical shape. The microsp~eres' are 'contact'ed with a dispersion of a quench fluid at a temperature of ~60 to -lOO~C which quickly cool~, solidifies and hardens the molten metal ,; prior to cooling and condensing the zinc vapor.
As the microsphere is further cooled, the zinc vapor condenses and depositg on the inner wall surface of the microsphere as a thin zinc metal coating.
~4~r, ~mooth, ~ollow glass ~icrospheres having an about 3000 to 4000 micron diameter, a 30 to 40 micron wall thickness and ~aving a zinc metal coating 325 to 4~0A thick and an internal contained pressure o~ 10 6 Torr are 'o'~t'ained.

s Example 3 A metal glas~ alloy composition i8 used to make hollow metal glass filamen~ed mierosphere~.
The metal glass composition is heated to a temperature above its liquidus temperature to form a flu;d molten metal glass. The molten metal gla~s just prior to the blowing operation can ha~e a viscosity of 100 to 200 poises.
The molten metal glass is ~ed to t~e apparatu~
of Figures 1 and 3 o~ the drawings under conditions similar to those used In Example 2.
A xenon or nitrogen blowing gas at abou~ the tempera~ure of the molten metal glass and a~ a positive pressure is applied to the inner sur~ace o~ the molten lSi metal glass film causing ~he film to distend outw~lrdly into an el`ongated cylinder shape with its ou~er end closed and its inner end attached to thP ou~er edge o~ orifice`7a'.
The transverse jet is used to direct an entraining 20 fluid wElich consists of nitrogen gas at about ~she temperature`o~ the molten metal glass at a linear ~eIocity of 5 to 40 feet a second over and around the ~lowing noxzle S which entraining fluid assists ln the ~ormation and closing of the elongated cylinder ~hape and the detac~in~ of the c~linder from the blowing nozzle while trailing a thin me~al glass filament which i~ continuou~.with the next microsphere forming a~: the ~low~ng nozzle, The ~ilamented metal mcirospheres are other~ise formed in the manner illustrated and 30 described with reerence to ~igure 3c of the drawi.ngs.
The transverse ~et is aligned relativ2 to ~he blowing no~zle as in Example 1.
The entrained elongated ilamented cylinder fllled wi~h the ~lowing ~as assumes a spherical shape. The Pilamented microspheres are contacted with a dispersion o~q~

of a quench fluid a~ a temper'ature'o~ -60 ~o 200~C.
which quickly cools, solidifies' and hardens the molten met'al glass to form filamented ~etal microspheres having arnorphous met~l walls. Depending on the queneh S conditions the co-llnecting met'al filaments can also be amorphous met'al, ~
~ lc~ moot~, hoI;low filamented metal glass ~ /
microsp~eres having an a~out 1500 to 2500 micron diameter andl.5 to 5.0 micron wall ~thickness are' obtained. The'lengths of the filarnent portions of the filamented microspheres' i5 10 to 20 times the diameter of the'microsphe'res.

~jii, Example 4 The Figure 5 of the drawings illustrates the use of the hollow metal microspheres of the present invention, in the construction of a formed panel 61. The panel contains multiple layers of unifor~ sized metal micro-spheres 62. The microspheres can have a thin deposited layer 63 of a met'al deposited on their inner wall surface. The internal volume'of the microspheres can contain a hard vacuum or can be filled with a low heat conductivity gas'64.
The hollow metal microspheres can be fused or sintered together by pressing them to,gether while passing an electric current thro~gh them. The micro-spheres' may be bonded together by using an inorganic bonding agent such as the CO~NI'NG solder glass or solder glass systems or by using an organic resin 30 adhesive. The formed panel 61 forms a light weight relatively s~rong metal'structure.

Ex'a'~p'l'e '5.
The'Figure'6 o~ the drawings illustrates the use o the' hollo~ met'al microsphere~ of the present invention in t~e construction of a ~ormed panel 7:1., The panel contains multiple layers of uniform sized flattened oblate 'spheroid shaped microspheres 72.
The o~late'spheroid shaped microspheres have an ilmer wall sur ace 73. The'internal volume of the micro-sphere'can be filled with a gas 74. The fla~tened configuration of the microspheres ~ubstantially reduce's the volume'o the interstices between the micxospheres'.
The'formed paneiI 71 can be formed by taking,the meta'l microspheres directly after they are formed, while 15' still hot, and compressing them between two surfaces to sinter or fuse 'the microspherestogether and to form the oblate'spheroid shape. Making the formed panel in this manner avoids t~e neces'sity of reheating the microspheres after' ~hey have cooled to ambient tempera~ures. The formed panel 71 forms a light weight relatively strong ~etal structure.' ~x~ ~
The ~igure 7 o~ t~e drawings illustrates the use of the met'al microspher'es' of the present in~ention to form a lig~t weight' metal struc~ure 61 having a con~inuous phase'of metal or metal alloy 65 and a discontinuous phase'of hollow met'al microspheres 62. The light weigh~
metal strurture'can be made in the form of a panel b~
uniform m~xing or dispers~ng the metal microspheres(until t~e'des'ired packIng i8 obtained)in a metal or metal alloy powder, compres'sing the mix~ure of metal powder and microspheres' ~o compact the mixture. The mixture is then heated under pressure to melt t~e met'al powder and is then quickly cooled before'~he'~lowing gas contained in the met'al microsphere can escape. A finished top surace 66 and bottom surface 67 can i~ desired by applied.

' ::
.

Exam~le 7 The Figure 7a of ~he drawings illus~rates the use of the metal microsphere~ o;f thie present invention to form a light weight metal structure 71 having a continuous phase of metal or metal alloy 77 and a discontinuous phase'of hollow metal microspheres 72.
The light weight me~al structure can be made in the form of a panel by uniformily mixing or dispersing the metal microspheres (until the desired packing ~s obtained)in a metal or metal alloy .p,owder,compressing the mixt~re to obtain the'oblate shaped spheroids while passing an electric current or otherwise heating ~he mixture . The mixture'is heated to a temperature isufficiently hig~ to ~inter or fuse the metal powder 15 ~i and met'al microspheres' together. The temperature used, however, is not high enough to melt or devitrify the met'al microspheres where they are made from a metal glass alloy having an amorphous structure. The formed panel containing the oblate'shaped metal microspheres can be used as a heat radiation ishiel~.

The Figure'7b of the drawings lllustrates an emb~diment of the formed wall panel of Figure 7a in which filamented hollow metaL microspheres connected by very thin met'al filaments 78 are used. The thin metal filaments 78 are formed between adjacent micro-spheres' when and as the microspheres are blown and ~oin the microspheres together by continuous me~al material. The'connecting filamients 78 in the formed paneI interrupt the wall ~o wall contact between th~e mlcrospheres'. The u8e of ~ilamented microspheres to provide the'interrupting,filaments is par~icularly advantageous and preferred because'the filaments are positi~ely e~enly distributed, cannot settle, are supplied in the'desired controlled amount, and in the 35~3 formed panel provide an interlocking structure which serves to strengthen the formed panel.
The oblate spheroid shape microspheres can have the ratio of the height to length of the microsphere of about 1 3.
The facing 76 can be uncoated or can have laminated or bonded thereto a finished surface. The backing surface 77 can be uncoated or can be painted or coated with a suitable resin to form a vapor seal.
The formed panels made in accordance with the present invention can be made to have a density gradient in the direction of the front to back of the panel. One of the surfaces can be made to have a relatively high density and high strength, by increasing the proportion of binder or continuous phase to metal microspheres. The other surface can be made to have relatively low density by having a high proportion of metal microspheres to binder or continuous phase.
For example, the front one-third of the panel can have an average density of about two to three times that of the average density of the center third of the panel. The density of the back one-third of the panel can be about one-half to one-third that of the center third of the panel.
The formed panels of the instant application can be used to form composite laminate light weight, high strength, high insulation value materials by fusing, sintering or bonding the panels of the instant applica~ion to hollow glass microsphere insulation pane]s.

~.. ..

,, UTILITY
The hollow metal microsphere~ of the present invention have many uses.
, The mlcrosphere can be used in transformers and ~lectric motors, and in magnetil~ cores.
The hollow metal microspheres when used as a component in building construction can retard the development and expansion of fires.
The formed metal microsphere panels can be used as magnetic shields. The metal glass microspheres because of their high strength and ductili.ty can be used as a filler mat~r:ial to make shock resistant plastic or resin automobile bumpers.
The me~al microsphere of the present invention when made from a film forming metal composition having ~, a hlgh melting temperature can be added directly to a molten metal of a lower temperature and cast in any des~red shape or form ~o ~orm light weight, high strength materia~s.
The microspheres can be bonded together by sintering or suit~ble res'in ad~esives and molded into sheets or other ~orms and used in constructions ~7hich require 'light wei'ght and high strength.
The metal microspheres may be adhered together with known adhesives' or binders to produce semi- or rigid cellular type materials ~or use in manuacturing various products or in construction. The microspheres, because t~ey are'made'from sta~le metal compositions, are not subject to degrada~on by outgassing, aging, mois~ure, weathe~ing or ~iological attack and do not produce toxic ~umes when exposed to high temperatures or ire..
The hol1Ow met'al microspheres when used in manufac~:ure of superior ligh~' weight structural materials can ad~antageousl~ ~' used alone or in combination with ~i~erglass, styro~o'a~, polyurethane'foam, phenol-ormalde~yde'~oam, organic 'and inor~anic binders and the'like.' ~. . .. ~ . . ... .

3S~3 The metal microspheres of the present invention can be used to make insula~ing materials and insula~ing wallboard and ceiling tiles. The microspheres can advantageously be used in plastic or resin boat construction to produce high strength hulls and/or hulls which themselves are buoyant.
The metal compositions can also be selected to produce microspheres that will be selectively permeable to specific gases and/or organic molecules. These microspheres can then be used as semi-permeable membranes to separate yaseous or liquid mixtures. The metal microsphere composi'Lions can also be formulated with catalytic metals and used in the chemical process industry.
The process and apparatus described herein can also be used to encapsulate and store gaseous material in hollow metal microspheres of a suitable non-interacting composition, therehy allowing storage or handlin~ of gases generally, and of corrosive and ~oxic or otherwise hazardous gases specifically. Because of the microspheres small size and relative great strength, the gases may be encapsulated into the hollow microspheres at elevated pressures, thus allowing high pressure storage of these gases. In the case where disposal by geological storage is desired, for example, for poisonous and/or other toxic gases, the gases can be encapsulated in very durable metal alloy composition microspheres which can subsequently be embedded, if desired, in a concrete structureO The metal microspheres of the present invention, because they can be made to contain gases under high pressure, can be used to manufacture fuel targets for laser fusion reactor systems, and since the microspheres are metal they may be suspended in a magnetic field.

V ~ 5.
~~7-These and other uses of the present inventio~
will become apparent to thoge sk~lled in the art ~rom the foregoing descriptlon and the ollowlng appended claims.
It will be understood that various change~ and modifications may ~e made in the invention, and that the scope thereof is no~ ~o be 1imited except as set forth in the claims.

i.

Claims (50)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Claim 1. A method for making hollow metal glass microspheres from a film forming metal material which comprises heating said material, forming a liquid film of said material across an orifice, applying a blowing gas at a positive pressure on the inner surface of the liquid film to blow the film and form the microsphere, subjecting the microsphere during its formation to an external pulsating or fluctuating pressure field having periodic oscillations, said pulsating or fluctuating pressure field acting on said microsphere to assist in its formation and to assist in detaching the microsphere from said orifice.
2. Claim 2. The method of Claim 1 wherein an entraining fluid is directed at an angle to a coaxial blowing nozzle having an orifice, an inner nozzle and an outer nozzle, the liquid film of film forming metal material is formed across the orifice, the blowing gas is conveyed to the inner surface of the liquid film through said inner nozzle, the film forming metal material is conveyed through said outer nozzle to said orifice, and the entraining fluid passes over and around said coaxial nozzle to fluid dynamically induce the pulsating or fluctuating pressure field at the opposite or lee side of the blowing nozzle in the wake or shadow of the coaxial blowing nozzle.
3. Claim 3. The method of Claim 2 wherein the lower portion of the outer nozzle is tapered inwardly to form with the outer edge of the orifice of the inner nozzle a fine gap and the film forming metal material is fed under pressure and extruded through said gap to form a thin film of film forming metal material across the orifice of the blowing nozz1e.
4. Claim 4. The method of Claim 2 wherein quench means direct a quench fluid into contact with said microsphere to rapidly cool at a rate of 104 to 106°C per second and solidify said microsphere.
5. Claim 5. The method of Claim2 wherein the film forming metal material has a viscosity of 20 to 100 poises.
6. Claim 6. The method of Claim2 wherein the film forming metal material has a viscosity of 100 to 400 poises.
7. Claim 7. A method for making hollow film forming metal glass material microspheres which comprises heating said metal material to form molten metal, forming a liquid film of molten metal across an orifice of a coaxial blowing nozzle, said blowing nozzle having an inner nozzle to convey a blowing gas to the inner surface of the liquid film and an outer nozzle to convey said molten metal to said orifice, applying said blowing gas through said inner nozzle at positive pressure on the inner surface of the liquid film to blow the film downwardly and outwardly to form the microsphere, continuously feeding said molten metal to said outer nozzle while said microsphere is being formed, directing an entrain-ing fluid at said coaxial blowing nozzle at an angle relative to a line drawn through the center axis of said coaxial blowing nozzle, said entraining fluid passing over and around said coaxial blowing nozzle to fluid dynamically induce a pulsating or fluctuating pressure field having periodic oscillations at the opposite or lee side of the blowing nozzle in the wake or shadow of said blowing nozzle, said entraining fluid acting on the microsphere to pinch and close-off the microsphere at a point proximate to the coaxial blowing nozzle and said entraining fluid acting to detach the microsphere from the coaxial blowing nozzle and rapidly cooling and solidifying said microsphere.
8. 69 Claim 9. The method of c1aim 7 wherein the lower portion of the outer nozzle is tapered inwardly to form with the outer edge of the orifice of the inner nozzle a fine gap and feeding the molten metal under pressure through said gap to form a thin film of molten metal across the orifice of the blowing nozzle.
9. Claim 9. The method of Claim 7 wherein said entraining fluid intersects said coaxial blowing nozzle at a point 0.5 to 4 times the outside diameter of the coaxial blowing nozzle above the orifice of said blowing nozzle and said entraining fluid is directed at said coaxial blowing nozzle through a transverse jet disposed a distance of 0.5 to 14 times the outside diameter of the coaxial blowing nozzle away from the point of inter-sect of a line drawn along the center axis of the transverse jet: and a line drawn along the center axis of the coaxial blowing nozzle.
10. Claim 10. The method of Claim 7 wherein the blowing gas is a metal vapor, the microsphere is cooled, hardened and solidified and a thin metal coating is deposited on the inner wall surface of the microspnere.
11. Claim 11. A method for making hollow film forming metal material microspheres which comprises heating metal glass alloy material to form molten metal, forming a liquid film of molten metal across an orifice of a coaxial blowing nozzle, said blowing nozzle having an inner nozzle to convey blowing gas to the inner surface of the liquid film and an outer nozzle to convey molten metal to said orifice, the lower portion of said outer nozzle being tapered inwardly to form with the outer edge of the inner nozzle a fine gap, feeding the molten metal under pressure through said gap and forming said . thin film of molten metal across said orifice of the blowing nozzle, applying said blowing gas through said inner nozzle at positive pressure on the inner surface of the liquid film to blow the film downwardly and out-wardly to form the microsphere, continuously feeding said molten metal to said outer nozzle while said microsphere is being formed, directing an entraining fluid at said coaxial blowing nozzle at an angle rela-tive to a line drawn through the center axis of said coaxial blowing nozzle, said entraining fluid passing over and around said coaxial blowing nozzle to fluid dynamically induce a pulsating or fluctuating pressure field having periodic oscillations at the opposite or lee side of the blowing nozzle in the wake or shadow of said blowing nozzle, said entraining fluid acting on the microsphere to pinch and close-off the microsphere at a point proximate to the coaxial blowing nozzle and said entraining fluid acting to detach the microsphere from the coaxial blowing nozzle, and rapidly cooling, solidifying and hardening said microsphere to obtain microspheres having a 500 to 6,000 microns diameter and a 0.5 to 400 microns wall thickness.
12. Claim 12. The method of Claim 11 wherein the microspheres are partially flattened to form oblate spheroids.
13. Claim 13. The method of Claim 11 wherein the microspheres.have a substantially uniform diameter.
14. Claim 14. A method for making filamented, hollow film forming metal material microspheres which comprises heating metal glass alloy material to form molten metal, forming a liquid film of molten metal across an orifice of a coaxial blowing nozzle, said blowing nozzle having an inner nozzle to convey blowing gas to the 'inner surface of the liquid film and an outer nozzle to convey molten metal to said orifice, the lower portion of said outer nozzle being tapered inwardly to form with the outer edge of the inner nozzle a fine gap, feeding the molten metal under pressure through said gap and forming said thin film of molten metal across said orifice of the blowing nozzle, applying said blowing gas through said inner nozzle at positive pressure on the inner surface of the liquid film to blow the film downwardly and out-wardly to form the microsphere, continuously feeding said molten metal to said outer nozzle while said microsphere is being formed, directing an entraining fluid at said coaxial blowing nozzle, at a linear velocity in the region of microsphere formation of about 1 to 50 feet per second to obtain connecting metal filaments between microspheres, and at an angle relative to a line drawn through the center axis of said coaxial blowing nozzle, said entraining fluid passing over and around said coaxial blowing nozzle to fluid dynamically induce a pulsating or fluctuating pressure field having periodic oscillations at the oppo-site or lee side of the blowing nozzle in the wake or shadow of said blowing nozzle, said entraining fluid acting on the microsphere to pinch and close-off the microsphere at a point proximate to the coaxial blowing nozzle and said entraining fluid acting to detach the microsphere from the coaxial blowing nozzle, and rapidly cooling, solidifying and hardening said microsphere to obtain microspheres having a 500 to 6,000 microns diameter and a 0.5 to 400 microns wall thickness, said microspheres being connected by thin filamented portions that are continuous with the metal glass alloy material microspheres.
15. Claim 15. The method of Claim 14 wherein the microspheres are partially flattened to from oblate spheroids.
16. Claim 16. The method of Claim 14 wherein the length of the connecting filaments is substantially equal and is 2 to 20 times the diameter of the microspheres.
17. Claim 17. The method of Claim 14 wherein the length of the connecting filaments is substantially equal and the diameter of the connecting filaments is 1/2500 to 1/20 the diameter of the microspheres.
18. Claim 18. The method of Claim 14wherein the microspheres have a substantially uniform diameter.
19. Claim 19. Hollow film forming metal glass material microspheres having a diameter of 200 to 10,000 microns and a wall thickness of 0.1 to 1,000 microns, wherein said microspheres are free of latent solid or liquid blowing gas materials or gases and the walls of said microspheres are substantially free of holes, relatively thinned wall portions or sections and bubbles.
20. Claim 20. The hollow microspheres of Claim 19 having a contained gas pressure of 5 to 100 p.s.i.a..
21. Claim 21. The hollow microspheres of Claim 19 having deposited on the inner wall surfaces thereof a thin metal coating 50 to 600°A thick.
22. Claim 22 The hollow microspheres of Claim 19 having 2 high contained vacuum of 10-4 of 10-6 Torrs.
23. Claim 23. The hollow microspheres of Claim 19 having a diameter of 500 to 3000 microns and a wall thickness of 0.5 to 200 microns.
24. Claim 24. The hollow microspheres of Claim 1 having an average bulk density of 0.5 to 30 lb/ft3.
25. Claim 25. Filamented, hollow film forming metal material microspheres having a diameter of 200 to 10,000 microns and a wall thickness of 0.1 to 1000 microns, wherein said microspheres are connected to each other by filament portions which are continuous with the microspheres and are of the same film forming metal material from which the microspheres are made.
26. Claim 26. Hollow metal glass alloy material microspheres having a diameter of 500 to 6,000 microns and a wall thickness of O. 5 to 400 microns, wherein said microspheres are free of latent solid or liquid blowing gas materials or gases and the walls of said microspheres are substantially free of holes, relatively thinned wall portions or sections, sealing tips and bubbles.
27. Claim 27, A mass of the microspheres of Claim 26
28. Claim 28. The hollow microspheres of Claim 26 having an oblate spheroid shape.
29. Claim 29. Filamented, hollow metal glass alloy material microspheres having a diameter of 500 to 6000 microns and a wall thickness of 0.5 to 400 microns, wherein said microspheres are connected to each other by filament portions which are continuous with the microspheres and are of the same metal glass alloy material from which the microspheres are made.
30. Claim 30. A mass of the microspheres of Claim 29.
31. Claim 31. The hollow microspheres of Claim 29 having an oblate spheroid shape.
32. Claim 32. The hollow microspheres of Claim 29 wherein the length of the connecting filaments is substantially equal and is 2 to 20 times the diameter of the microspheres.
33. Claim 33. The hollow microspheres of Claim 29 wherein the length of the connecting filaments is substantially equal and the diameter of the connecting filament is 1/2500 to 1/20 the diameter of the microspheres.
34. Claim 34. A shaped form or formed mass of cemented or bonded together hollow film forming metal material microspheres having a diameter of 200 to 10,000 microns and a wall thickness of 0.1 to 1,000 microns.
35. Claim 35. The shaped form or formed mass of microspheres of Claim 34, wherein said microspheres have a diameter of 500 to 3000 microns and a wall thickness of 0.5 to 200 microns.
36. Claim 36. The shaped form or formed mass of microspheres of Claim 34 wherein the shaped form or formed mass comprises said microspheres and a member selected from the group consisting of plastics, resins, concrete and asphalt.
37. Claim 37. A shaped form or formed mass of cemented or bonded together filamented, hollow film forming metal material microspheres having a diameter of 200 to 10,000 microns and a wall thick-ness of 0.1 to 1000 microns, wherein said micro-spheres are connected to each other by filament portions which are continuous with the microspheres and are of the same film forming metal material from which the microspheres are made.
38. Claim 38. The shaped form or formed mass of micro-spheres of Claim 37 wherein the shaped form or formed mass comprises said microspheres and a member selected from the group consisting of plastics, resins, concrete and asphalt.
39. Claim 39. A shaped form or formed mass of cemented or bonded together hollow metal glass alloy material microspheres having a diameter of 500 to 6,000 microns and a wall thickness of 0.5 to 400 microns, wherein said microspheres are free of latent solid or liquid blowing gas materials or gases and the walls of said microspheres are substantially free of holes, relatively thinned wall portions or sections, sealing tips and bubbles.
40. Claim 40. The shaped form or formed mass of micro-spheres of Claim 39 wherein the microspheres are cemented together by fusion or sintering or are bonded together with an organic or inorganic bonding agent or adhesive.
41. Claim 41. The shaped form or formed mass of microspheres of Claim 39 wherein the microspheres comprise a filler material.
42. Claim 42. The shaped form or formed mass of micro-spheres of Claim 40 formed into a thin sheet or panel.
43. Claim 43. The shaped form or formed mass of micro-spheres of Claim 42, wherein said microspheres have an oblate spheroid shape.
44. Claim 44. A shaped form or formed mass of cemented or bonded together filamented, hollow metal glass alloy material microspheres having a diameter of 500 to 6000 microns and a wall thickness of 0.5 to 400 microns, wherein said microspheres are connected to each other by filament portions which are continuous with the microspheres and are of the same metal glass alloy material from which the microspheres are made.
45. Claim 45. The shaped form or foxed mass of microspheres of Claim 44 wherein the microspheres are cemented together by fusion or sintering or are bonded together with an organic or inorganic bonding agent or adhesive.
46. Claim 46. The shaped form or formed mass of microspheres of Claim 44 wherein the microspheres comprise a filler material.
47. Claim 47. The shaped form or formed mass of micro-spheres of Claim 45 formed into a thin sheet or panel.
48. Claim 48. The shaped from or formed mass of micro-spheres of Claim 47, wherein said microspheres have an oblate spheroid shape.
49. Claim 49. The shaped form or formed mass of micro-spheres of Claim 45 wherein the length of the connecting filaments is substantially equal and is 2 to 20 times the diameter of the microspheres.
50. Claim 50. The shaped form or formed mass of micro-spheres of Claim 45 wherein the length of the connecting filaments is substantially equal and the diameter of the connecting filament is 1/2500 to 1/20 the diameter of the microspheres.