PROCESS FOR FORMING A CERAMIC LAYER

• US 20080312748A1
• Filed: 06/18/2007
• Published: 12/18/2008
• Est. Priority Date: 06/18/2007
• Status: Active Grant

• Current Assignee: Zimmer Incorporated (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Zimmer Incorporated (Zimmer Biomet Holdings, Inc.)
• Inventors: Popoola, Oludele, Anderson, Jeffrey P.
• Granted Patent: US 8,133,553 B2
• Time in Patent Office: Days
• US Class Current: 623/23.11
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2002/30929 having at least two superposed coatings
• CPC Class Codes: A61F 2310/00634 Coating made of zirconium oxide or hydroxides
• CPC Class Codes: A61L 27/306 Other specific inorganic materials not covered by A61L27/303 - A61L27/32
• CPC Class Codes: C23C 14/083 of refractory metals or yttrium
• CPC Class Codes: C23C 14/46 by ion beam produced by an external ion source
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

A process for forming a ceramic layer comprising a compound of a metal on a deposition surface of a workpiece comprises providing a reactive gas, selecting the amounts of a vapor of the metal and ions of the metal relative to each other, generating the metal vapor, and projecting an ion beam of the metal ions. The metal vapor, the metal ions, and the reactive gas form the ceramic layer with a desired structure. The process may include the step of controlling a deposition surface temperature. In one embodiment, the metal vapor comprises zirconium vapor and the ion beam comprises zirconium ions. The relative amounts of the zirconium vapor and the zirconium ions are selected to form a zirconia ceramic layer on the deposition surface. The zirconia may have multiple crystal phases that are formed according to a predetermined ratio.

Claims

1. A process for forming a ceramic layer comprising a compound of a metal on a deposition surface of a workpiece, the process comprising:

providing an reactive gas in fluid communication with the deposition surface of the workpiece;

generating a vapor of the metal in fluid communication with the deposition surface;

projecting an ion beam comprising a plurality of ions of the metal onto the deposition surface; and

selecting amounts of the vapor of the metal and the ions of the metal relative to each other, wherein the reactive gas, the vapor of the metal, and the ions of the metal react at the selected amounts to form the ceramic layer having a desired structure on the deposition surface.

2. The process of claim 1 wherein the deposition surface has a deposition surface temperature, and the process further comprises controlling the deposition surface temperature to between approximately 25°

C. and approximately 1000°

C.

3. The process of claim 1 wherein the deposition surface has a deposition surface temperature, and the process further comprises controlling the deposition surface temperature to between approximately 200°

C. and approximately 600°

C.

4. The process of claim 1 wherein the reactive gas has a partial pressure sufficient to react with substantially all of the vapor of the metal and the ions of the metal.

5. The process of claim 1 wherein selecting amounts of the vapor of the metal and the ions of the metal relative to each other with both the vapor of the metal and the ions of the metal to form the ceramic layer having the desired structure with at least two crystal phases.

6. The process of claim 5 wherein at least two crystal phases are formed in a predetermined ratio.

7. The process of claim 1 wherein the reactive gas comprises oxygen having a partial pressure of less than approximately 2×

10<sup>−

5</sup> torr, the vapor of the metal comprises zirconium vapor, and the ions of the metal comprises zirconium ions, and wherein the oxygen, the zirconium vapor, and the zirconium ions react to form a zirconia ceramic layer having the desired structure on the deposition surface.

8. The process of claim 7 wherein selecting amounts of the zirconium vapor and the zirconium ions relative to each other whereby the oxygen reacts with both the zirconium vapor and the zirconium ions to form the zirconia ceramic layer having the desired structure comprising two or more of a monoclinic phase, a tetragonal phase, or a cubic phase on the deposition surface.

9. The process of claim 7 wherein selecting amounts of the zirconium vapor and the zirconium ions relative to each other whereby the oxygen reacts with both the zirconium vapor and the zirconium ions to form the zirconia ceramic layer having the desired structure comprising a monoclinic phase, wherein the monoclinic phase has a plurality of monoclinic crystals with a preferred crystallographic orientation on the deposition surface.

10. The process of claim 7 wherein selecting amounts of the zirconium vapor and the zirconium ions relative to each other whereby the oxygen reacts with both the zirconium vapor and the zirconium ions to form the zirconia ceramic layer having the desired structure comprising a monoclinic phase and a tetragonal phase on the deposition surface.

11. The process of claim 10 wherein the monoclinic phase and the tetragonal phase form in a predetermined ratio of a volume of the monoclinic phase to a volume of the tetragonal phase and the predetermined ratio is between approximately 0 and approximately 0.6.

12. The process of claim 11 wherein the zirconium vapor is generated with an evaporator, an amount of the zirconium vapor is related to an evaporator power supplied to the evaporator, an amount of the zirconium ions in the ion beam is related to an ion beam power supplied to an ion source, and during selecting amounts of the zirconium vapor and the zirconium ions relative to each other, the ion beam power is selected such that a ratio of the ion beam power to the evaporator power is between approximately 50 and approximately 1000.

13. The process of claim 12 wherein the ion beam power is determined by an ion beam voltage and an ion beam current, and during selecting the amount of the zirconium ions, the ion beam voltage is selected between approximately 20 keV and approximately 60 keV and the ion beam current is selected between approximately 250 μ

A and approximately 500 μ

A.

14. An orthopedic implant comprising:

an orthopedic body having a deposition surface; and

a ceramic layer formed on the deposition surface, wherein the ceramic layer has a desired structure comprising at least two crystal phases.

15. The implant of claim 14 wherein the ceramic layer comprises zirconia and the at least two crystal phases include a monoclinic zirconia and a tetragonal zirconia.

16. The implant of claim 15 wherein a volume of the monoclinic zirconia to a volume of the tetragonal zirconia is between approximately 0 and approximately 0.6.

17. The implant of claim 14 wherein the ceramic layer comprises zirconia and the at least two crystal phases includes a monoclinic zirconia having a plurality of monoclinic crystals in a preferred orientation on the deposition surface.

18. The implant of claim 14 wherein the ceramic layer comprises zirconia and the desired structure comprises a monoclinic zirconia, a tetragonal zirconia, or a cubic zirconia, or a combination thereof.

19. The implant of claim 14 wherein the ceramic layer has a thickness of less than approximately 5 microns.

20. The implant of claim 14 wherein the orthopedic body is a femoral hip ball implant or a femoral knee implant.