TRIBOLOGICAL STUDY OF DIAMOND COATINGS ON TITANIUM-ALLOYS

This paper presents the tribological characteristics of PACVD diamond coatings on titanium alloys. The coating morphology and quality have b een investigated by SEM and Raman spectroscopy, and the surface roughn ess has been determined by AFM measurements. Friction and wear charact eristics have been studied with a pin-on-disk tribometer as a function of the applied load, the sliding speed and the counterface material. For diamond-on-diamond contact, the dynamic friction coefficient stabi lizes at a value of 0.05-0.08 after the surface polishing of diamond c rystal tips. For non-diamond coated pins, a surface running in time at low sliding speed is necessary to avoid a coating spalling on the dis k. After this step, the sliding speed can be increased to 1 m s(-1) wi th a friction coefficient equal to or lower than 0.1. The wear of the diamond-coated disk generally cannot be measured. (C) 1997 Elsevier Sc ience S.A.