Patent ID: 8172958

Claim:
A method of making a surface hardened medical implant comprising the steps of: forming a medical implant of zirconium or zirconium alloy; treating said implant by one of (a), (b), or (c), wherein (a), (b), and (c) are defined as follows: (a) treating said implant in the presence of ceramic-forming species at a temperature of less than 700 degrees C. for greater than 5 minutes; and, thereafter diffusion hardening said implant by treating said implant under vacuum or inert gas at a temperature of from 500 degrees C. to 1000 degrees C. for greater than 1 hour; (b) treating said implant in the presence of ceramic-forming species at a temperature of from 500° C. to 1000° C.; and, thereafter diffusion hardening said implant by treating said implant under vacuum or inert gas at a temperature less than 700 degrees C.; (c) treating said implant in the presence of ceramic-forming species at a temperature of less than 700 degrees C.; and, thereafter diffusion hardening said implant by treating said implant under vacuum or inert gas at a temperature less than 700 degrees C.; and determining a period of time to perform the diffusion hardening step, said determination based at least on a desired hardness profile of at least a portion of said implant defined by a function selected from the group consisting of: an error function, an exponential function, a near uniform distribution function, and any sequential combination thereof.