Method for improving the wear performance of ceramic-polyethylene or ceramic-ceramic articulation couples utilized in orthopaedic joint prostheses

Abstract

Methods for improving the wear performance of silicon nitride and/or other ceramic materials, particularly to make them more suitable for use in manufacturing biomedical implants.

What is claimed is: 
     
         1 . A silicon oxynitride material, wherein the silicon oxynitride material has improved wear performance, and wherein the silicon oxynitride material is prepared by a process comprising:
 forming a silicon nitride material block; and   oxidizing the silicon nitride material block.   
     
     
         2 . The product of the process of  claim 1 , wherein forming the silicon nitride material block comprises:
 preparing a slurry comprising silicon, oxygen, and nitrogen, and further comprising at least one of yttrium oxide and aluminum oxide;   milling the slurry; and   drying the slurry to obtain a dried slurry.   
     
     
         3 . The product of the process of  claim 1 , wherein the silicon oxynitride material comprises a first crystalline phase and a first amorphous phase. 
     
     
         4 . The product of the process of  claim 1 , wherein oxidizing the silicon nitride material block is performed using hydrothermal oxidation. 
     
     
         5 . The product of the process of  claim 4 , wherein the hydrothermal oxidation is performed in a steam autoclave. 
     
     
         6 . The product of the process of  claim 4 , wherein the hydrothermal oxidation is conducted at a pressure ranging from about 1 atmosphere to about 250 atmospheres. 
     
     
         7 . The product of the process of  claim 4 , wherein the hydrothermal oxidation is conducted at a pressure of about 2 atmospheres. 
     
     
         8 . The product of the process of  claim 4 , wherein the hydrothermal oxidation is conducted at a temperature ranging from about 100° C. to about 150° C. 
     
     
         9 . The product of the process of  claim 4 , wherein the hydrothermal oxidation is conducted at a temperature ranging from about 120° C. to about 135° C. 
     
     
         10 . The product of the process of  claim 4 , wherein the hydrothermal oxidation is conducted at a temperature of about 132° C. 
     
     
         11 . The product of the process of  claim 4 , wherein the hydrothermal oxidation is conducted for a duration ranging from about 50 to about 200 hours. 
     
     
         12 . The product of the process of  claim 4 , wherein the hydrothermal oxidation is conducted for a duration ranging from about 70 to about 150 hours. 
     
     
         13 . The product of the process of  claim 4 , wherein the hydrothermal oxidation is conducted for a duration of about 72 hours. 
     
     
         14 . The product of the process of  claim 1 , wherein the silicon nitride material block is an articulation component of a prosthetic joint. 
     
     
         15 . The product of the process of  claim 14 , wherein the articulation component is a femoral head. 
     
     
         16 . The product of the process of  claim 14 , wherein the improved wear performance increases the longevity of the prosthetic joint greater than 15 years. 
     
     
         17 . The product of the process of  claim 14 , wherein the silicon nitride material has a surface chemistry that protects a counter surface of the articulation component from oxidation. 
     
     
         18 . The product of the process of  claim 17 , wherein the counter surface is an acetabular polyethylene cup.