DE2135444A1 - Lightweight metal composition and method of making it - Google Patents

Description

Dr. rer. nat. Horst pupil PATENT ADVOCATE

Frankfurt / Main 1, July 1st, 1971

Niddasfraße 52 Dr. S Gh./Se.

Telephone (0611) 237220 • Postal check account: 282 420 Frankfurt / M.

Bank account: 523/3168

Deutsche Bank AG, Frankfurt / M.

K / 948

Claimed priorities:

July 17, 1970, Japan, August 10, 1970, Japan,

No. 62114/1970 No. 69218/1970

Applicant: KUREHA KAGAKU KOGYC KABUSHIKI KAISHA No. 8, Horidome-cho 1-chome Nihonbashi, Chuo-ku Tokyo / JAPAN

Lightweight metal composition and process for their manufacture

The invention relates to a porous, lightweight metal composition consisting of a basic component of aluminum, an aluminum alloy or a magnesium alloy, and it further relates to a method for producing this metal composition. The invention relates in particular to a porous, borrowed weight metal composition which contains a

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Contains metal or an alloy as a basic component and is hollow Has micro-spherical shells made of a material which corresponds to the sintering temperature of the metal or alloy and it further relates to a method of making the same Metal composition.

In recent years, there has been a need for ultra-light weight Metal materials for use in partition walls, soundproof walls and as thermal insulation material, which found use in skyscrapers or as building materials for airplanes, automobiles or other vehicles. For satisfaction This demand was already light metals, e.g. by gas ^ foamed light metals, foamed plastics, which with ™ were coated with light metals. The foamed However, metals have the disadvantage that they have poor strength and thermal insulation properties are unsatisfactory because they contain continuous, interconnected foam pores. With those with Metal-coated foamed plastics have the disadvantage that they are in their heat resistance properties are unsatisfactory because their plastic substrate is easily subject to thermal decomposition.

It is therefore the main object of the present invention to provide, in an economical manner, ultra-light-weight metal materials k which are excellent in strength properties and heat resistance properties and furthermore have good thermal insulation and soundproofing properties. It has been found that a porous, lightweight metal composition suitable for this purpose can be made by sintering a mixture of aluminum, an aluminum-based alloy or a magnesium-based alloy and hollow microsphere shells of a material which withstands the sintering temperature.

The porous, lightweight metal composition of the present invention is characterized in that it has a structure similar to a so-called;

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syntactic form is where the heat-resistant hollow Micro-spherical shells are distributed homogeneously in a continuous phase of the metal or alloy. The lightweight Metal composition therefore not only has an extremely high specific compressive strength (compressive strength per volume weight), but it is also excellent in terms of heat insulation and sound-absorbing properties and it also has the property of being impermeable. The invention is described in greater detail below explained.

The metals used as the base material in the present invention include aluminum and alloys on aluminum or Magnesium base. In the case of alloys, the aluminum can or magnesium is preferably contained therein in an amount of at least 70 percent by weight. The aluminum-based alloys include aluminum-magnesium, aluminum-silicon, aluminum-manganese, aluminum-copper, aluminum-silicon-magnesium, Aluminum-magnesium-manganese; while the magnesium-based alloys include those which, for example, have a low Amount of aluminum, zinc, manganese and / or silicon.

As already described above, the heat-resistant hollow microsphere shells, which are provided with a such metal are mixed to form a material which corresponds to the sintering temperature of the powdered metals used, which is generally above about 500 C, for example around hollow micro-spherical shells with a maximum diameter 2 mm, a particle density of maximum 1 g / cm and a hydrostatic compressive strength of at least 1.0 kg / cm, those made from a carbonaceous material such as carbon or graphite, from a ceramic material such as a hard one Glass, natural glass, silicon dioxide or aluminum oxide or composed of a metal such as copper, nickel or iron are. Such hollow micro-spherical shells and a method for Generation of the same is in our own earlier Japanese patent application 45625 / SHO. 45 (1970) or in the corresponding!

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German patent application P 21 26 2 62.4.

A variety of means can be used to mix the metal with the hollow microsphere shells. If the metal used is in the form of fine particles with an average particle size of 100 / U or less, the metal is dry-mixed with the hollow microsphere shells by means of an ordinary mixer. V-shaped mills, vibratory mills, for example, are particularly advantageous for this treatment , Vibratory mills, conical mills, kneaders and Henshelmisoher etc. If the metal used is in the form of γοη coarse granules, pieces, plates or rods, the metal * 'is preferably treated in a steel melt-stirrer, where the metal is melted and then mixed with the hollow microsphere shells so that the surface of the hollow microsphere shells can be coated with the metal non-oxidizing gas, such as argon To carry out hydrogen or helium.

The surface of the hollow microsphere shells can be activated before the mixing treatment in order to improve the wetting with the metal and achieve good adhesion between the two and an improvement in the quality of the end products. Treatment with a metal salt flux is suitable for such activation. The treatment temperature door is not critical, but is generally carried out at a temperature below ⁰ 4-00 O. Metal salts useful for this treatment _? include chlorides or fluorides of the alkali metals _p alkaline earth metals and aluminum, including SnGl ₂ * - NaF / ALF », SnGl _o / laGl, IL F ^ / ifaf / Köl / IaGls the particularly preferred Biss® metal salts can la form a mixture of zvsel or more with a lower melting point or in the form of a solution in a solvent such as water or an alcohol. If the used hollow micro-

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Ball shells are composed of a non-metallic substance, the activation treatment can be done with the help of a electrically or chemically plating the surface of the hollow particles with copper or winding, and if desired, the aforementioned activation treatment can also be applied to the coated surface.

The mixing ratio between the metal and the hollow microsphere shells depends on the desired strength and Density of the molded objects or on the nature of the hollow micro-shells used. The metal will, however used at least in an amount that is necessary to the To fill gaps between the hollow microspherical shells formed in the mixture during the sintering treatment composite material are in the closest packing. It has been found that the use of the metal in an amount of at least 15 to 85, based on the ■ volume ratio is necessary to achieve the desired strength in the molded objects.

A variant of the present invention comprises the use of a mixture of the metal and the hollow microsphere shells in which a thermosetting binder is further incorporated. By using such a thermosetting binder, it is achieved that the metal is mixed with the hollow microsphere shells so that the surface of the microsphere shells is coated with the metal. The mixture is heated to harden the binder and is then sintered. The thermosetting binder used in the invention include organic, inorganic or organometallic compounds which readily cure at temperatures ranging from ordinary temperature to about 35O ⁰ O. The organic compounds include thermosetting resins such as silicone resins, phenol resins, furfural and furfuryl alcohol resins, epoxy resins, unsaturated polyester resins. The inorganic compounds used are advantageously: hydrated potassium silicate, hydrated lithium silicate, lower polymers of ethyl; Silicate. As organometallic compounds are preferred

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lower polymers of the alkyl titanates, aluminum alkoxides, etc. are used. These thermosetting binders are preferred is selected depending on the kind of materials constituting the hollow microsphere shells. For example The organic compounds are preferably used when the hollow microsphere shells are made of a carbonaceous Material are composed; the inorganic compounds are preferably used when the hollow microsphere shells are composed of a ceramic material and the organometallic compounds are preferably used when the hollow micro-ball shells are composed of a metal. The thermosetting binders are in a

P is used in such an amount that when the mixture is molded under pressure, hardened by heating and then sintered, the structure of the molded article can be maintained. In this case, care must be taken that an excess of the binder can have an adverse effect on the strength and appearance of the desired shaped object. The amount of binder is generally selected to be in the range of 2-15 percent by volume based on a mixture of the metal and the microsphere shells. When the binder is mixed together with the metal and the hollow microsphere shells, a volatile, vaporizable liquid can be added to facilitate mixing of these materials and forming this mixture under pressure to increase packing density. As such a liquid, common organic solvents such as aliphatic hydrocarbons, alkyl ethers _? Alkyl esters and alcohols can be used when the binder is an organic compound or an organometallic compound. In the case that an inorganic binder is used, water and alcohols are preferably used. These volatile liquids are removed in the subsequent heating stage. The resulting mixture of the metal and the granular hollow microsphere shells or the mixture of the metal, the hollow microsphere shells and the thermosetting binder is then subjected to the molding under pressure and the "\"

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- 7 - Subjected to sintering.

In the molding and sintering treatment, a Mixture of the material and the granular hollow microsphere shells are sintered by heating while under pressure is deformed. In this case, it is advantageous to use a device for compression deformation with a external or internal heating device is provided. The pressure applied during this molding treatment is preferably in the range of 10-200 kg / cm. However, if the granular hollow micro-ball shells have a smaller Have hydrostatic compressive strength, it is desirable to apply a correspondingly lower pressure to a Prevent collapse of the hollow micro-ball shells. The volume of the mixture placed in the molding apparatus shrinks when the mixture is heated to sinter the metal it contains. It is therefore necessary to print the mold to readjust continuously. The heating to effect sintering is carried out in such a way that the die heated by high frequency when external heat is added or by adding electricity directly to the mixture in the Die or discharge is performed when internal heating is performed. In case of a Internal heating, ceramic or carbonaceous materials are used as the mold.

When the mixture to be sintered is composed of a metal, hollow micro-spherical shells and a thermosetting binder, the mixture is put in an ordinary metal mold and molded under a pressure of 10-200 kg / cm. After molding, the mixture is usually from 5 minutes to 24 hours at a temperature of 100 - 300 ⁰ C is heated to cause curing of the binder contained therein. If necessary, the shaping and the curing can be carried out simultaneously by heating. To achieve hardening, the heating can either take place at a constant temperature or by gradually increasing the temperature, starting from the usual temperature.

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A shaped and hardened article is then heated to a temperature at which the metal is sufficiently sintered. The sintering treatment is usually carried out by heating the article for 5-60 minutes in an oven which is kept at a temperature above 50O ⁰ O, preferably 700-1000 ° 0. If the hollow microsphere shells used are composed of a carbonaceous material, the sintering treatment is preferably carried out in an atmosphere of argon, hydrogen or helium.

This sintering treatment · results in a porous, lightweight Metal composition. According to the present invention

"The resulting lightweight metal composition has a structure in which the hollow microsphere shells are homogeneously distributed in the base metal which forms a continuous phase. Since the space between the dispersed granular hollow microsphere shells is compactly filled with metal, the metal composition is extremely lightweight due to the porosity and has excellent strength j heat insulation property and sound-absorbing property _e The porous lightweight metal composition according to the invention is therefore ^ as already described above *, not only for partition walls _p soundproof material and thermal insulation material in skyscrapers, but

) also as building material for airplanes, automobiles and others. vehicles in a wide variety of applications torao.oli "bai? _D

With the help of the following examples, the present invention is also further elaborated, however, these examples are only used for explanation, without any other areas of the invention

example 1

Good IFerweMm & g of a kl®ia @ a Heiisli © l ~ Miao! IerB were in an Irgoaataiosphere 3? 9 g carbon-iialtiger hollow micro = alt ®in®M aittl © s? @A IMrsiiiaesser von

«I m <ö \ ß) f> s S 1 *% c π I ys β d 4 / S 4 'a U

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Bulk density of 0.12 g / cm and a hydrostatic compressive strength of about 50 kg / cm, homogeneous with 28 g of spherical aluminum powder with an average diameter of 35 / U with a fresh surface and 14 g of flaky aluminum powder with an average diameter of 20 / U with fresh surface mixed. The mixture was immediately placed in a small hot press fitted with a high frequency heating device. The sample space had a diameter of 30 mm and a height of 150 mm and was filled with argon. The mixture was purified by 30 minutes heating at 700 - 75O ⁰ C sintered under a pressure of 50 kg / cm. The apparent density of the obtained porous material composition was 1.2 g / cm. The composite material had excellent strength in spite of its very light weight.

The compressive strength and modulus of compressive elasticity of the composite material thus obtained were 492 kg / cm (7000 psi) and 21,100 kg / cm ² (300 χ 10 ⁵ psi), respectively.

Example 2

The same carbonaceous hollow microsphere shells as described in Example 1 were made with a saturated solution of zinc chloride in acetone treated for 30 minutes at room temperature, dried under reduced pressure, mixed with aluminum powders in a manner similar to that described in Example 1 and sintered. In In this case, a composite material was used with

recorded strength and an apparent density of 1.2 g / cm by 30 minutes heating at 700 - 75O ⁰ C under a molding pressure of 50 kg / cm was obtained.

The compressive strength and the modulus of compressive elasticity of the composite material thus obtained were 506 kg / cm · i

(7,200 psi) or 22,820 kg / cm ² (326 10 ⁵ psi.);

Example 3

5.5 g hard glass hollow microsphere shells with a mean diameter of about 60 / \ x, a bulk density

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of 0.21 g / cm ^5, a particle density of 0.42 g / cm and a hydrostatic compressive strength of 40 kg / cm, 20 minutes at 35O ⁰ O with a molten mixture of zinc chloride and sodium chloride (weight ratio 80: 20) treated for to activate the surface of the particles and then in a small Henshel mixer homogeneously with 28 g of spherical aluminum powder with an average diameter of 35 / u and 14 g of flaky aluminum powder with an average diameter of 20 / u in a similar manner as in Example 1 is described, mixed.

The mixture was sintered by heating for 30 minutes at 700 - ρ 750 ⁰ O under a pressure of 40 kg / cm in a similar manner as described in Example 1, and a lightweight material composition with an apparent density of 1.55 was obtained g / cm and excellent strength.

The compressive strength and modulus of compressive elasticity of the composite material thus obtained were 429 kg / cm (6,100 psi) and 17,500 kg / cm ² (250 10 ⁵ psi), respectively.

Example 4

The same carbonaceous hollow particles used in Example 1 were coated with a 1 / u thick layer of copper using a non-electrolytic plating process to form hollow microsphere shells with a bulk density of 0.28 g / cnr and a particle density of 0.44 g / cm. cnr to result. The particles were further treated with a molten mixture of sodium fluoride and aluminum fluoride (weight ratio -36:64) to activate the surface of the particles. 42 g of aluminum pellets (0.7 mm in diameter and 0.7 mm in height) with a purity of over 99 »9 $ were then admixed and the mixture was placed in a 200 ml stainless steel autoclave and heated with stirring with an alurainium-coated stirrer, to melt the aluminum * After melting, 10 g of the hollow micro-cymes were exposed and the heating was applied vigorously

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Continue stirring for 30 minutes at the melting temperature. The mixture was then slowly ^{cooled to below 200 °} C. and removed from the autoclave, fine granular hollow particles being obtained which consisted of the hollow microsphere shells which were evenly coated with aluminum.

These hollow particles were placed in a graphite mold having a cylindrical cross section of 12 mm in diameter and a Height of 50 mm and with the bottom and the top were covered with graphite disks. The shape was between arranged opposite pistons and a direct current of 5 volts and 2,000 amperes as well as a high frequency current of 5 volts, 300 amps and 1,000 Hz (1,000 c / s) were passed under a pressure of 70 kg / cm with heating and sintering was effected. The porous composite material obtained had an apparent density of 1.35 g / cm and excellent strength

The compressive strength and the modulus of compressive elasticity of the so

The resulting composite materials were 548 kg / cm (7,800 psi) and 23,800 kg / cm ² (.340 10 ⁵ psi), respectively.

Example 5

3.5 g of granular carbonaceous hollow microsphere shells with a mean diameter of 100 / U, a bulk density

¹ x ft.

of 0.12 g / cm, a particle density of 0.20 g / cm and a hydrostatic compressive strength of about 50 kg / cm, 11 g of flaky aluminum powder with a purity of over 99.0 i * and an average diameter of 35 / rev , a thermosetting silicone varnish (KR 255, a product of Shin-etsu Kagaku KK) and Tuluol were mixed homogeneously in a Henshel mixer. The mixture was pressed in a metal mold under a pressure of up to 50 kg / cm into a plate 10 mm thick. The extruded sheet was heated for 4 hours in an oven, which was maintained at 250 ⁰ O to complete curing of the silicone coating to reach and simultaneously the Suluol to remove. This plate was overall by 30 minutes long heating · in an electric furnace with an argon atmosphere at 75O ⁰ C

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sinters and an aluminum composite material having a density of 1.2 g / cm and excellent strength was obtained. The compressive strength and modulus of compressive elasticity of the composite material thus obtained were 4-22 kg / cm ² (6,000 psi) and 17,500 kg / cm ² (250 10 psi), respectively.

Example 6

4.6 g of hard glass micro-spherical shells with a diameter of 60 / u, a bulk density of 0.21 g / cm, one

/ χ
Particle density of 0.42 g / am and a hydrostatic pressure

strength of 40 kg / cm, 11g flaky aluminum powder) with a purity of more than 99.0 i ° and an average diameter of 20 / U, 22 g spherical aluminum powder with a purity of over 99 »O fi and an average diameter of 35 / u and 6 g of a low polymer of ethyl silicate (ethyl silicate 40, a product of Nippon Korukoto Chemicals Co.) were homogeneously mixed in a Henshel mixer. The mixture was pressed in a metal mold under a pressure of 40 kg / cm into a sheet 8 mm thick. The molded plate was heated for 4 hours in a maintained at 25O ⁰ G oven to cause curing of the Äthylsilicats and complete removal of the volatile decomposition products and then 15 minutes further heated in an electric oven at 75O ⁰ C to k a composite material with a density of 1.5 g / cm. and excellent strength.

The compressive strength and the modulus of compressive elasticity of the composite material thus obtained were 259 kg / cm (5,100 psi) and 14,700 kg / cm ² (210 10 ⁵ psi), respectively.

Example 7

They are like granular carbonaceous hollow micro-spherical shells, as they were used in Example 1, with copper in a diolce of about 1 / u with the help of a non-electrolytic Beschiohtung procedure covered. It was a bulk density and a rope foil oil elite of the old KuOfer over- »

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drawn granular hollow microsphere shells which were 0.28 g / cm 5 and 0.44 g / ^{cm 3, respectively.}

8.5 g of these particles, 11 g of flaky aluminum powder, which has already been used above, 22 g of spherical aluminum powder and 5 g of a lower polymer of butyl titanate were mixed homogeneously in a Henshel mixer and

molded in a metal mold under a pressure of 100 kg / cm ze a plate of 9 mm thick. The molded plate was heated for 5 hours at 25O ⁰ G, in order to achieve a complete curing dea binder and sintered long then replaced by 30 minutes of heating in a furnace with an argon atmosphere at 75O ⁰ C to obtain a composite material having a density of * 1.3 g / cm and excellent strength. The compressive strength and modulus of compressive elasticity of the composite material thus obtained were 457 kg / cm ² (6,500 psi) and 20,300 kg / cm ² (290 χ psi), respectively.

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Claims (10)

-H- claims 1. Porous lightweight metal composition, thereby characterized in that it is produced by pressing and sintering a mixture of a metal selected from the group Aluminum, an aluminum-based alloy and a magnesium-based alloy is selected and hollow Micro-spherical shells composed of one material which withstands the sintering temperature of the metal has been obtained and has a structure in which the hollow micro-spherical shells are homogeneously distributed in the metal. 2. Porous, lightweight metal composition characterized in that it is formed by pressing, hardening and sintering a mixture of a metal selected from the group consisting of aluminum, an aluminum-based alloy and a Magnesium-based alloy is selected, hollow micro-ball shells, which are composed of a material which withstands the sintering temperature of the metal and a thermosetting binder and has a structure in which the hollow microsphere shells are homogeneously distributed in the metal 3. A method for producing the porous, lightweight metal composition according to claim 1, characterized in that a metal selected from the group consisting of aluminum, an aluminum-based alloy and a magnesium-based alloy, with granular hollow microsphere shells made of a material which withstands the sintering temperature of the metal, are mixed in such a way that the surface of the hollow microsphere shells is coated with the metal and then the mixture is sintered under the conditions of compression deformation by heating . 4. Process for producing the porous, lightweight 109884/1360 Metal composition according to claim 2, characterized in that a metal selected from the group consisting of aluminum, a Aluminum-based alloy and magnesium-based alloy is selected, with hollow micro-spherical shells, which are composed of a material which withstands the sintering temperature of the metal, and with a thermosetting binder is mixed together, the Mixture is heated under the conditions of compression deformation or after the compression deformation treatment, whereby the Binder is cured in the mixture and then the mixture is sintered. 5. Porous, lightweight metal composition according to claims 1 and / or 2, characterized in that the hollow micro-spherical shells are composed of a material selected from the group consisting of carbon, graphite, hard glass, natural glass, silicon dioxide, aluminum oxide, copper, nickel and iron is selected. 6. Porous, lightweight metal composition according to claim 2 characterized in that the thermosetting binder from the group of thermosetting resins, such as silicone resins, phenolic resins, furfurylaldehyde resins and furfuryl alcohol resins, epoxy resins and unsaturated polyester resins; hydrated potassium silicate; hydrated Lithium silicate; Low polymers of ethyl silicate; liiederpolymers of alkyl titanates; and aluminum alkoxides is selected. 7. The method according to claims 3 or 4, characterized in that that the mixing ratio between the metal j and the hollow microsphere shells in proportions by volume j is at least 15 to 85. - j 8. The method according to claim 4, characterized in that \ the proportion of the thermosetting binder is at most \ 15 percent by volume, based on a mixture of the metal 'j and the hollow microsphere cups. 109884/1360 2135U4 9 · Process according to claims 3 _t 4 _f 7 and 8, characterized in that the hollow micro-spherical shells are mixed with the metal after their surface has been activated 10. The method according to claims 1-4, characterized in that that during the pressure treatment the pressure is about 10 200 kg / cm. 109884/1360