Implanted layers improved wear

Ion implantation, coating by plasma methods, and anodic oxidation [122] have all been used to improve the wear behavior of T16AI4V surfaces. Coating with DLC layers [ 123] and with TiN by PVD have been successful in decreasing the wear of the spherical alloy components (the balls ) in hip joints and have been extensively investigated [124], For knee joints with their rather complicated geometry, ion implantation seems to be the preferred method. The ef-... 

In the ca.se of the implantation of N and C, the microstructural investigations revealed the formation of precipitates that had a beneficial influence on the macroscopic wear behavior, contrary to those implantation conditions in which a continuous layer was fonned. If the layer enriched in precipitates formed by ion implantation extends as far as the surface, the number of scratches is reduced and wear behavior is improved. The most pronounced reduction in the number of scratches and in the wear volume of the UHMWPE counterpart was achieved for N or C implantation at energies that allowed the precipitates to be formed immediately beneath the outer oxide layer. If the formation of a continuous layer is to be avoided, the total ion dose should not exceed 10 cm -. 

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