Wear behavior of carbide coated Co-Cr-Mo implant alloy.

The wear behavior of a new type of metal carbide surface coating on Co-Cr-Mo implant alloy was studied. The coating was created using a microwave plasma-assisted reaction. Codeposition of impurity diamond film, diamond particles, and soot was prevented by controlling process conditions. Wear tests were carried out using a sapphire ball-on-Co-Cr-Mo disc unidirectional sliding configuration with harsh conditions of high contact stress and slow sliding speed in both no-lubrication, and deionized water lubrication environments. In the case of uncoated Co-Cr-Mo discs, the effect of deionized water lubrication was remarkable and reduced the wear factor by one order of magnitude compared to the no-lubrication tests. The wear factor of carbide coated Co-Cr-Mo discs was slightly smaller than that of uncoated Co-Cr-Mo discs with deionized water lubrication (2.7 x 10(-6) mm3 N(-1) m(-1) vs. 4.2 x 10(-6) mm3 N(-1) m(-1)). The addition of deionized water lubrication did not greatly affect the wear factor of carbide coated Co-Cr-Mo discs. The influence of surface geometry resulting from the "brain coral-like" surface morphology of carbide layers on wear behavior was analyzed considering stress concentrations and effective contact area.