CA1140215A - Zirconia insulation systems - Google Patents
Zirconia insulation systemsInfo
- Publication number
- CA1140215A CA1140215A CA000293746A CA293746A CA1140215A CA 1140215 A CA1140215 A CA 1140215A CA 000293746 A CA000293746 A CA 000293746A CA 293746 A CA293746 A CA 293746A CA 1140215 A CA1140215 A CA 1140215A
- Authority
- CA
- Canada
- Prior art keywords
- zirconia
- relation
- zirconium
- layer
- group
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
- H01B3/12—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances ceramics
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/02—General constructional details
- G01R1/06—Measuring leads; Measuring probes
- G01R1/067—Measuring probes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B17/00—Insulators or insulating bodies characterised by their form
- H01B17/56—Insulating bodies
- H01B17/62—Insulating-layers or insulating-films on metal bodies
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
- H01B3/10—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances metallic oxides
- H01B3/105—Wires with oxides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F5/00—Coils
- H01F5/06—Insulation of windings
Abstract
Case 2539 ABSTRACT OF THE DISCLOSURE
Electrical devices suitable for use in difficult environments include portions thereof made from material selected from the group comprising zirconium and zirconium alloy. The component parts are manufactured in an electrically non-insulated condition and pre-assembled in potentially mutual shortcircuited relation, and then processed in order to develop a zirconia insulating layer, even in the case where intimate shortcircuiting contact exits. In some instances at least, there is no imperative need to roughen the surfaces prior to formation of the zirconia protective layer. The thickness of the layer can be controlled to enhance the security of interfitted parts.
Electrical devices suitable for use in difficult environments include portions thereof made from material selected from the group comprising zirconium and zirconium alloy. The component parts are manufactured in an electrically non-insulated condition and pre-assembled in potentially mutual shortcircuited relation, and then processed in order to develop a zirconia insulating layer, even in the case where intimate shortcircuiting contact exits. In some instances at least, there is no imperative need to roughen the surfaces prior to formation of the zirconia protective layer. The thickness of the layer can be controlled to enhance the security of interfitted parts.
Description
ll~Q~S Case 2539 This invention is directed to an improved electrical insulation system, and in particular to a zirconia-insulated system, and the manufacture thereof.
In the operation of nuclear reactors, it is often desirable to detect or measure what is taking place within the reactor, using electrical probes, coils and the like.
Owing to the highly hostile environment existing within the confines of reactors such as the Candu reactors, wherein a strong field of radiation exists in a water-filled corrosive environment, and wherein flows of water at high velocity take place, it has not been found possible to install sensor probes or electrical sensor coils, owing to the rapid deterioration of the insulation within the environment. Thus, the usually alkaline water, at a temperature in excess of 300C rapidly attacks glass and even quartz.
In the prior art, in Canadian Patent No. 822,775, which issued September 9, 1969 in the name of Robert D. Watson, etal, there is shown the provision of a Zircaloy-2 alloy, comprising 1.2 to 1.7 per cent tin; 0.07 to 0.2 per cent iron; 0.05 to 0.15 per cent chromium; 0.03 to 0.08 per cent nickel and the balance zirconium, the alloy being in the form of a slotted tube intended for use as an electrical heating element, wherein insulation is provided by utilizing a zirconia layer thereon.
The formation of the desired beige-coloured zirconia layer of Zr 2 is obtained in accordance with the teaching of Canadian Patent No. 770,080, which issued October 24, 1967 in the name of Robert D. Watson et al.
In addition to the teachings of Watson et al, as set forth in the referenced patents, it has been found that a satisfactory adherent layer of zirconia can be formed on wires and ribbons of many zirconium alloys, including Zircaloy-2, using the methods formulated by Watson et al, but ~ 215 Case 2539 .
without, in some instances having to resort to the surface roughening processes adopted by Watson.
Furthermore, it has been found that the benefits of a zirconia insulative layer may be obtained in the case of electrical coils of zirconium alloy (hereinafter referred to as ZA) and for electrical probes of ZA extending through ZA plates and other ZA surfaces, wherein the assemhly parts that are intended for use as conductors are assemkled in mutual short circuiting relation, and also wherein the conducting portions are assembled in short circuited relation with elements of the system which are intended for use as insulators. It has been found that upon heating these afore-mentioned conductlve and insulative components to a temperature in the order of 600 to 650C, a highly effective layer of zirconia is formed, providing electrical insulation, even where short-circuit conditions previously existed. In the case even of ZA components press-fitted together, the oxidizing process can effectively penetrate and insulate the elements from each other. The zirconia layer thus formed, in addition to providing excellent electrical insulation serves to support components in mutually secured relation, owing to the increase in mutual physical interference provided by the swelling at the respective surfaces which takes place as the zirconia is formed. The insulative zirconia surface also is found to be virtually self-healing within the reactor environment since the oxide reforms upon exposure to high temperature water.
One envisaged use of the present invention is the incorporation of a copper or other highly conductive conductor within a ZA tube. ZA tubes having outer diameters in the order of one millimeter are available, for use in such a process. By oxidizing the tube to form a zirconia layer on the outer surface, there is obtained a superior insulated ~4~ Case 2539 conductor for use within hostile environments. Before carrying out the oxidation conversion step, the tube may be reduced in diameter by swaging or by die drawing, to bring it into intimate gripping relationship with the conductor.
The resulting composite structure provides a conductor having a lower electrical resistance than a ZA conductor of the same diamater.
Certain embodiments are described, reference being made to the accompanying drawings wherein;
Figure 1 shows a zirconium alloy component in accordance with the present disclosure;
Figure 2 shows a conductive probe and insulative support plate in accordance with the invention, with enlarged detail at Fig. 2A;
Figure 3 shows a composite conductor in accordance with the invention;
Figure 4 is a section view at 4-4 of Figure 3;
Figure 5 is a like view after swaging or die drawing; and Figure 6 shows a conductive probe within a shielding support tube in accordance with the invention.
In Figure 1 there is shown a coil 10 having a conductor 12 wound into a plurality of turns with an outer layer of turns 14 and an inner layer 16 of turns of smaller diameter than the turns 14. The conductor may be of ZA wire or a composite conductor having a ZA outer surface. The coil may be wound upon a ZA former 18. The ZA alloy of each turn is in intimate contact with adjacent turns and with the former 18, to form a short circuit condition such that the application of voltage between the ends 20, 22 of the conductor would result in the passage of a short circuit current from turn to turn and from the inner turns 14 and the ends 20, 22 ~ lS Case 2539 of the conductor to the former 18.
Subjecting the coil to the known oxidation process, comprising heating in the range 600C to 650~C in air produces oxidation of the ZA to produce an adherent layer of zirconia. The zirconia coats all of the wire, so that no short circuit condition exists between any of the turns or between the conductor and the former and the application of normal voltage between the ends 20,22 of the conductor will result in the passage of a normal operating current around the turns of the coil.
Referring to Figure 2, there is shown a coil 30 having leads 32, 34 extending through bores in a plate 36. The coil 30 and plate 36 are of ZA and the relative dimensions permit a close but non-interference fit assembly.
- Also shown is a probe 37 of ZA having a contact point 38 made of a metal which does not oxidize on exposure to air or water athigh temperature (such as platinum), the contact point being welded or brazed at 39 to probe 37.
The probe 37 extends through plate 36 ;the relative dimensions permit a close but non-interference fit assembly.
After completion of the oxidation process the zirconia layer created on the ZA components serves to secure them together in an interference fit. The plate 36 now serves as an insulator. The coil 30 and the probe 37 are electrically insulated all over, by the layer of zirconia, except for th~e contact point 38 on the end of probe 37.
It will be evident that components of extreme complexity may be fabricated in ZA, and subsequently transformed as desired to provide an insulation layer of zirconia thereon, even to electrically isolate parts fabricated in iniimate contact.
Figure 3 illustrates the construction of a 1~4Q2~S
Case 2539 composite conductor. A highly conductive conductor 40 such as copper is threaded through a sheath 42 of Zircaloy-2 alloy, as shown in section in Figure 4.
In Figure 5 the assembly is shown after swaging, or die-drawing. If then oxidized, the outer surface 45 of sheath 42 becomes zirconia, and serves to insulate the conductor 40.
In E'igure 6 is shown an electrode 50 made of a metal (such as platinum) which does not oxidize or corrode in high temperature water,having a lead 54 extending through the bore of a tubular member 52 fabricated of Z~ which has oxidized on its inner and outer surfaces. The surface oxide layer serves to insulate the member 52 from the electrode 50 and lead 54 and also from the surrounding environment which may be a conductive medium such as water. In addition to supporting the electrode 50, the metallic member 52 may be connected electrically to act as a shield for lead 54, to avoid resistive and capacitative coupling to the surrounding environment.
It will be evident from the foregoing that an insulation system of unexpected versatility is hereby provided, wherein the advantages of working in ductile metallic elements, to close tolerances and in forms of almost unlimited complexity while yet possessing the potentiality of separating selected components of the assembly with a highly durable insulation is herein provided.
In the operation of nuclear reactors, it is often desirable to detect or measure what is taking place within the reactor, using electrical probes, coils and the like.
Owing to the highly hostile environment existing within the confines of reactors such as the Candu reactors, wherein a strong field of radiation exists in a water-filled corrosive environment, and wherein flows of water at high velocity take place, it has not been found possible to install sensor probes or electrical sensor coils, owing to the rapid deterioration of the insulation within the environment. Thus, the usually alkaline water, at a temperature in excess of 300C rapidly attacks glass and even quartz.
In the prior art, in Canadian Patent No. 822,775, which issued September 9, 1969 in the name of Robert D. Watson, etal, there is shown the provision of a Zircaloy-2 alloy, comprising 1.2 to 1.7 per cent tin; 0.07 to 0.2 per cent iron; 0.05 to 0.15 per cent chromium; 0.03 to 0.08 per cent nickel and the balance zirconium, the alloy being in the form of a slotted tube intended for use as an electrical heating element, wherein insulation is provided by utilizing a zirconia layer thereon.
The formation of the desired beige-coloured zirconia layer of Zr 2 is obtained in accordance with the teaching of Canadian Patent No. 770,080, which issued October 24, 1967 in the name of Robert D. Watson et al.
In addition to the teachings of Watson et al, as set forth in the referenced patents, it has been found that a satisfactory adherent layer of zirconia can be formed on wires and ribbons of many zirconium alloys, including Zircaloy-2, using the methods formulated by Watson et al, but ~ 215 Case 2539 .
without, in some instances having to resort to the surface roughening processes adopted by Watson.
Furthermore, it has been found that the benefits of a zirconia insulative layer may be obtained in the case of electrical coils of zirconium alloy (hereinafter referred to as ZA) and for electrical probes of ZA extending through ZA plates and other ZA surfaces, wherein the assemhly parts that are intended for use as conductors are assemkled in mutual short circuiting relation, and also wherein the conducting portions are assembled in short circuited relation with elements of the system which are intended for use as insulators. It has been found that upon heating these afore-mentioned conductlve and insulative components to a temperature in the order of 600 to 650C, a highly effective layer of zirconia is formed, providing electrical insulation, even where short-circuit conditions previously existed. In the case even of ZA components press-fitted together, the oxidizing process can effectively penetrate and insulate the elements from each other. The zirconia layer thus formed, in addition to providing excellent electrical insulation serves to support components in mutually secured relation, owing to the increase in mutual physical interference provided by the swelling at the respective surfaces which takes place as the zirconia is formed. The insulative zirconia surface also is found to be virtually self-healing within the reactor environment since the oxide reforms upon exposure to high temperature water.
One envisaged use of the present invention is the incorporation of a copper or other highly conductive conductor within a ZA tube. ZA tubes having outer diameters in the order of one millimeter are available, for use in such a process. By oxidizing the tube to form a zirconia layer on the outer surface, there is obtained a superior insulated ~4~ Case 2539 conductor for use within hostile environments. Before carrying out the oxidation conversion step, the tube may be reduced in diameter by swaging or by die drawing, to bring it into intimate gripping relationship with the conductor.
The resulting composite structure provides a conductor having a lower electrical resistance than a ZA conductor of the same diamater.
Certain embodiments are described, reference being made to the accompanying drawings wherein;
Figure 1 shows a zirconium alloy component in accordance with the present disclosure;
Figure 2 shows a conductive probe and insulative support plate in accordance with the invention, with enlarged detail at Fig. 2A;
Figure 3 shows a composite conductor in accordance with the invention;
Figure 4 is a section view at 4-4 of Figure 3;
Figure 5 is a like view after swaging or die drawing; and Figure 6 shows a conductive probe within a shielding support tube in accordance with the invention.
In Figure 1 there is shown a coil 10 having a conductor 12 wound into a plurality of turns with an outer layer of turns 14 and an inner layer 16 of turns of smaller diameter than the turns 14. The conductor may be of ZA wire or a composite conductor having a ZA outer surface. The coil may be wound upon a ZA former 18. The ZA alloy of each turn is in intimate contact with adjacent turns and with the former 18, to form a short circuit condition such that the application of voltage between the ends 20, 22 of the conductor would result in the passage of a short circuit current from turn to turn and from the inner turns 14 and the ends 20, 22 ~ lS Case 2539 of the conductor to the former 18.
Subjecting the coil to the known oxidation process, comprising heating in the range 600C to 650~C in air produces oxidation of the ZA to produce an adherent layer of zirconia. The zirconia coats all of the wire, so that no short circuit condition exists between any of the turns or between the conductor and the former and the application of normal voltage between the ends 20,22 of the conductor will result in the passage of a normal operating current around the turns of the coil.
Referring to Figure 2, there is shown a coil 30 having leads 32, 34 extending through bores in a plate 36. The coil 30 and plate 36 are of ZA and the relative dimensions permit a close but non-interference fit assembly.
- Also shown is a probe 37 of ZA having a contact point 38 made of a metal which does not oxidize on exposure to air or water athigh temperature (such as platinum), the contact point being welded or brazed at 39 to probe 37.
The probe 37 extends through plate 36 ;the relative dimensions permit a close but non-interference fit assembly.
After completion of the oxidation process the zirconia layer created on the ZA components serves to secure them together in an interference fit. The plate 36 now serves as an insulator. The coil 30 and the probe 37 are electrically insulated all over, by the layer of zirconia, except for th~e contact point 38 on the end of probe 37.
It will be evident that components of extreme complexity may be fabricated in ZA, and subsequently transformed as desired to provide an insulation layer of zirconia thereon, even to electrically isolate parts fabricated in iniimate contact.
Figure 3 illustrates the construction of a 1~4Q2~S
Case 2539 composite conductor. A highly conductive conductor 40 such as copper is threaded through a sheath 42 of Zircaloy-2 alloy, as shown in section in Figure 4.
In Figure 5 the assembly is shown after swaging, or die-drawing. If then oxidized, the outer surface 45 of sheath 42 becomes zirconia, and serves to insulate the conductor 40.
In E'igure 6 is shown an electrode 50 made of a metal (such as platinum) which does not oxidize or corrode in high temperature water,having a lead 54 extending through the bore of a tubular member 52 fabricated of Z~ which has oxidized on its inner and outer surfaces. The surface oxide layer serves to insulate the member 52 from the electrode 50 and lead 54 and also from the surrounding environment which may be a conductive medium such as water. In addition to supporting the electrode 50, the metallic member 52 may be connected electrically to act as a shield for lead 54, to avoid resistive and capacitative coupling to the surrounding environment.
It will be evident from the foregoing that an insulation system of unexpected versatility is hereby provided, wherein the advantages of working in ductile metallic elements, to close tolerances and in forms of almost unlimited complexity while yet possessing the potentiality of separating selected components of the assembly with a highly durable insulation is herein provided.
Claims (12)
1. An electrical device having an electrical current conductor portion and a structural support portion, each said portion being pre-assembled in non-insulated relation with the other portion, one of said portions being selected from the material group consisting of zirconium and zirconium alloy, and an electrical insulating portion comprising an adherent layer of beige coloured zirconia applied in-situ by oxidation of said selected material when in assembled relation with said other portion, said layer being in a substantially mechanically unstressed condition.
2. The device as claimed in claim 1, said electrical current conducting portion being of copper.
3. The device as claimed in claim 1, said electrical current conducting portion being selected from said zirconium and zirconium alloy.
4. The device as claimed in claim 1, said zirconia holding said conductor in secured and insulated relation with said structural support means.
5. The device as claimed in claim 1, said structural support means comprising a plate having said current conducting portion passing through an aperture therein, being spaced and electrically insulated therefrom by said zirconia portion.
6. The device as claimed in claim 1, said conductor being of copper, and having a sleeve thereover of material selected from said group, and a layer of zirconia thereover.
7. The device as claimed in claim 1, said current conducting portion comprising a winding having a plurality of turns in physical contacting relation, said contacting surfaces being of zirconia.
Case 2539
Case 2539
8. The device as claimed in claim 1, comprising a probe having a central core of material selected from said group, a substantially non-oxidizable tip thereon, and a coating of zirconia in protective, electrically insulating relation about the core.
9. The device as claimed in claim 1, comprising a central core portion of substantially non-oxidizable metal having a sleeve selected from said material extending thereabout, said sleeve having the surfaces thereof covered with zirconia.
10. The device as claimed in claim 1, claim 2 or claim 3, wherein said zirconia layer provides stabilizing mechanical contact between a predetermined section of at least one said portion and another portion of the device.
11. The device as claimed in claim 8 or claim 9 wherein said zirconia layer provides stabilizing mechanical contact between a predetermined section of at least one said portion and another portion of the device.
12. The method of manufacturing an electrical device having at least two metallic portions wherein at least one said portion is fabricated from material selected from the group comprising zirconium and zirconium alloy, including the steps of:
a) fabricating the respective metallic portions with at least the exposed, surface of said at least one portion being selected from said group;
b) assembling said metallic portions in intimate mutually contacting relation; and c) heating the assembled portions in an oxidizing atmosphere to a temperature in the range 600°C to 650°C for a time sufficient to produce an adherent coating of beige coloured zirconia in insulating relation over the surface of said one selected portion;
Case 2539
12. The method of manufacturing an electrical device having at least two metallic portions wherein at least one said portion is fabricated from material selected from the group comprising zirconium and zirconium alloy, including the steps of:
a) fabricating the respective metallic portions with at least the exposed, surface of said at least one portion being selected from said group;
b) assembling said metallic portions in intimate mutually contacting relation; and c) heating the assembled portions in an oxidizing atmosphere to a temperature in the range 600°C to 650°C for a time sufficient to produce an adherent coating of beige coloured zirconia in insulating relation over the surface of said one selected portion;
Case 2539
Claim 12 continued:
whereby said one portion is isolated in electrically insulated relation.
whereby said one portion is isolated in electrically insulated relation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000293746A CA1140215A (en) | 1977-12-22 | 1977-12-22 | Zirconia insulation systems |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000293746A CA1140215A (en) | 1977-12-22 | 1977-12-22 | Zirconia insulation systems |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1140215A true CA1140215A (en) | 1983-01-25 |
Family
ID=4110365
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000293746A Expired CA1140215A (en) | 1977-12-22 | 1977-12-22 | Zirconia insulation systems |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1140215A (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5037438A (en) * | 1989-07-25 | 1991-08-06 | Richards Medical Company | Zirconium oxide coated prosthesis for wear and corrosion resistance |
| US5152794A (en) * | 1989-07-25 | 1992-10-06 | Smith & Nephew Richards Inc. | Zirconium oxide and nitride coated prothesis for reduced microfretting |
| US5180394A (en) * | 1989-07-25 | 1993-01-19 | Davidson James A | Zirconium oxide and nitride coated prosthesis for wear and corrosion resistance |
| US5258022A (en) * | 1989-07-25 | 1993-11-02 | Smith & Nephew Richards, Inc. | Zirconium oxide and nitride coated cardiovascular implants |
| US5370694A (en) * | 1989-07-25 | 1994-12-06 | Smith & Nephew Richards, Inc. | Zirconium oxide and nitride coated endoprostheses for tissue protection |
| US5496359A (en) * | 1989-07-25 | 1996-03-05 | Smith & Nephew Richards, Inc. | Zirconium oxide and zirconium nitride coated biocompatible leads |
| US5588443A (en) * | 1989-07-25 | 1996-12-31 | Smith & Nephew Richards, Inc. | Zirconium oxide and zirconium nitride coated guide wires |
| US5628790A (en) * | 1989-07-25 | 1997-05-13 | Smith & Nephew, Inc. | Zirconium oxide zirconium nitride coated valvular annuloplasty rings |
-
1977
- 1977-12-22 CA CA000293746A patent/CA1140215A/en not_active Expired
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5037438A (en) * | 1989-07-25 | 1991-08-06 | Richards Medical Company | Zirconium oxide coated prosthesis for wear and corrosion resistance |
| US5152794A (en) * | 1989-07-25 | 1992-10-06 | Smith & Nephew Richards Inc. | Zirconium oxide and nitride coated prothesis for reduced microfretting |
| US5180394A (en) * | 1989-07-25 | 1993-01-19 | Davidson James A | Zirconium oxide and nitride coated prosthesis for wear and corrosion resistance |
| US5258022A (en) * | 1989-07-25 | 1993-11-02 | Smith & Nephew Richards, Inc. | Zirconium oxide and nitride coated cardiovascular implants |
| US5370694A (en) * | 1989-07-25 | 1994-12-06 | Smith & Nephew Richards, Inc. | Zirconium oxide and nitride coated endoprostheses for tissue protection |
| US5496359A (en) * | 1989-07-25 | 1996-03-05 | Smith & Nephew Richards, Inc. | Zirconium oxide and zirconium nitride coated biocompatible leads |
| US5588443A (en) * | 1989-07-25 | 1996-12-31 | Smith & Nephew Richards, Inc. | Zirconium oxide and zirconium nitride coated guide wires |
| US5611347A (en) * | 1989-07-25 | 1997-03-18 | Smith & Nephew, Inc. | Zirconium oxide and zirconium nitride coated percutaneous devices |
| US5628790A (en) * | 1989-07-25 | 1997-05-13 | Smith & Nephew, Inc. | Zirconium oxide zirconium nitride coated valvular annuloplasty rings |
| US5632779A (en) * | 1989-07-25 | 1997-05-27 | Smith & Nephew, Inc. | Zirconium oxide and zirconium nitride coated vascular grafts |
| US5647858A (en) * | 1989-07-25 | 1997-07-15 | Smith & Nephew, Inc. | Zirconium oxide and zirconium nitride coated catheters |
| US5649951A (en) * | 1989-07-25 | 1997-07-22 | Smith & Nephew Richards, Inc. | Zirconium oxide and zirconium nitride coated stents |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |