Cobalt chrome coated titanium implant

• US 9,370,605 B2
• Filed: 03/04/2013
• Issued: 06/21/2016
• Est. Priority Date: 03/04/2013
• Status: Active Grant

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Inventors: Zhang, Zongtao, Hanson, Keenan Michael, McCarthy, Thomas Francis, Lawrynowicz, Daniel E., Wang, Aiguo
• Primary Examiner(s): SELLMAN, CACHET I
• Application Number:
  US13/783,894
• Publication Number:
  US 20140249642A1
• Time in Patent Office: 1,205 Days
• Field of Search: 427/2.24, 427/2.26, 427/2.27
• US Class Current: 1/1
• 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 2/32 for the hip
• CPC Class Codes: A61F 2002/30934 Special articulating surfaces
• CPC Class Codes: A61F 2002/3208 Bipolar or multipolar joints, e.g. having a femoral head articulating within an intermediate acetabular shell whilst said shell articulates within the natural acetabular socket or within an artificial outer shell
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00413 Coating made of cobalt or of Co-based alloys
• CPC Class Codes: A61L 2420/02 Methods for coating medical devices
• CPC Class Codes: A61L 2420/08 Coatings comprising two or more layers
• CPC Class Codes: A61L 2430/02 for reconstruction of bones; weight-bearing implants
• CPC Class Codes: A61L 27/06 Titanium or titanium alloys
• CPC Class Codes: A61L 27/306 Other specific inorganic materials not covered by A61L27/303 - A61L27/32
• CPC Class Codes: C23C 14/16 on metallic substrates or on substrates of boron or silicon

Abstract

A method for coating an orthopedic implant made of a titanium or titanium alloy substrate with a cobalt-chrome molybdenum alloy uses multi-arc physical vapor deposition (MA-PVD). The substrate has a first bearing surface coated with a coating made of the deposited cobalt-chromium molybdenum alloy. The bearing surface slidably receives a second bearing surface of the prosthetic joint component. The MA-PVD cobalt-chromium molybdenum alloy coating forming the first bearing surface is made up of hexagonal close packed (HCP) grains having a columnar structure with a length of about 1 μm and a width of about 0.1 μm with the length of each HCP grains being oriented generally perpendicular to the titanium substrate bearing surface.

Claims

1. A method for manufacturing a prosthetic implant comprising:

providing a substrate comprising titanium;

coating a surface of the substrate with a cobalt-chromium molybdenum alloy by multi-arc physical vapor deposition to produce a majority of grains having a hexagonal close pack (HCP) phase, the cobalt-chrome molybdenum alloy comprising about 66 weight percent cobalt, 27.9 weight percent chromium, and about 5.1 weight percent molybdenum; and

polishing the cobalt-chromium molybdenum HCP coating.

2. The method as set forth in claim 1 wherein the grain sizes are between 0.1 and 1.0 μ

m.

3. The method as set forth in claim 1 wherein the substrate is a commercially pure titanium or a titanium alloy.

4. The method as set forth in claim 1 wherein the HCP grains have a columnar grain structure wherein the grains have a length which is perpendicular to the substrate surface.

5. The method as set forth in claim 4 wherein the columnar grains are about 1 μ

m long and 0.1 nm wide.

6. The method as set forth in claim 1 wherein the polishing is performed by a polishing process selected from the group consisting of a media polishing process, a sequential grade SiC wheel grinding an Al₂O₃ slump polishing process and a soft wheel polishing process.

7. The method as set forth in claim 6 wherein the surface roughness is Ra<

50 nm after polishing.

8. The method as set forth in claim 6 wherein the surface roughness is Ra<

25 nm.

9. The method as set forth in claim 1 wherein the polished cobalt-chrome HCP coating has a hardness greater than 500 Vickers Diamond Pyramid Hardness (DPH) at a 25 g load.

10. The method as set forth in claim 1 wherein the coating is greater than 30% chromium plus molybdenum.

11. The method as set forth in claim 1 wherein the cobalt-chrome molybdenum alloy coating is between 6 and 100 μ

00 m before polishing.

12. The method Os set forth in claim 11 wherein the cobalt-chrome molybdenum alloy coating is between 5 and 95 μ

m thick after polishing.