Method of surface hardening cobalt-chromium based alloys for orthopedic implant devices

A method of manufacturing a cobalt-chromium orthopedic implant device having enhanced surface hardness and wear resistance properties, comprising the steps of:

• providing a cobalt-chromium substrate in the form of an orthopedic implant device;
• and
• exposing the cobalt-chromium substrate to an atmosphere of molecular nitrogen gas at a process temperature and for a process time duration sufficient to cause nitrogen dissolution in the cobalt-chromium substrate without a substantial quantity of formation of a substantial quantity of chromium nitride on the surface of said the cobalt-chromium substrate, thereby enhancing the surface hardness and wear resistance properties of the cobalt-chromium substrate by substantially avoiding increased surface roughness and brittleness that would diminish the wear resistance properties.

A method of increasing the surface hardness and wear resistance properties of an orthopedic implant device that is fabricated from a cobalt-chromium material, comprising the steps of:

• providing a substrate of cobalt-chromium material in the form of an orthopedic implant device;
• and
• exposing the substrate to an atmosphere of non-diluted molecular nitrogen gas at a process temperature and for a process time duration sufficient to enhance both surface hardness and wear resistance properties of said substrate by nitrogen dissolution in the substrate by substantially avoiding increased surface roughness and brittleness and thereby diminishing wear resistance properties by the formation of a substantial quantity of chromium nitride on the surface of the substrate.

A method of manufacturing a cobalt-chromium orthopedic implant device having enhanced wear resistance properties, comprising the steps of:

• providing a cobalt-chromium substrate in the form of an orthopedic implant device;
• and
• hardening the surface of the cobalt-chromium substrate by exposing the cobalt-chromium substrate to an atmosphere of ionized nitrogen at a process temperature within the range of 500.degree. F. to 2400.degree. F. for a process time duration sufficient to achieve a hardened outer surface layer and a hardened diffusion layer characterized primarily by solid solution hardening of the surface of the cobalt-chromium substrate by dissolution of nitrogen and oxygen in the cobalt-chromium substrate.

A method of manufacturing a cobalt-chromium orthopedic implant device having enhanced surface hardness and wear resistance properties, comprising the steps of:

• providing a cobalt-chromium substrate in the form of an orthopedic implant device;
• and
• exposing the cobalt-chromium substrate to an atmosphere of ionized nitrogen at a process temperature and for a process time duration sufficient to cause nitrogen dissolution in the cobalt-chromium substrate without formation of a substantial quantity of chromium nitride on the surface of said the cobalt-chromium substrate, thereby enhancing the surface hardness and wear resistance properties of the cobalt-chromium substrate by substantially avoiding increased surface roughness and brittleness that would diminish the wear resistance properties.

A method of increasing the surface hardness and wear resistance properties of an orthopedic implant device that is fabricated from a cobalt-chromium material, comprising the steps of:

• providing a substrate of cobalt-chromium material in the form of an orthopedic implant device;
• and
• exposing the substrate to an atmosphere of ionized nitrogen at a process temperature and for a process time duration sufficient to enhance both surface hardness and wear resistance properties of said substrate by nitrogen dissolution in the substrate by substantially avoiding increased surface roughness and brittleness and thereby diminishing wear resistance properties by the formation of a substantial quantity of chromium nitride on the surface of the substrate.