Dry sliding wear mechanisms of HIPIMS plasma nitrided CoCrMo alloy for medical implant applications

Unlike the state-of-the-art plasma nitriding technologies where a low ionisation glow discharge is used, of CoCrMo alloy was carried out in an industrial size vacuum coater, utilising novel high ionisation, power impulse magnetron sputtering mixed with unbalanced discharge. Three different voltages were used for process. To generate more ions, two pairs Cr and Nb targets also operated at N2:H2 gas atmosphere. Dry sliding pin on disc tests performed room temperature to measure coefficient friction estimate wear coefficient. In case samples nitrided lower bias such as ?700 V ?900 V, oxidative mild mechanism identified dominant mechanism. For higher voltage ?1100 despite formation oxide based tribolayer, severe abrasion predominant due operation three body contact involving hardness particles. Among samples, sample best lowest Kc = 1.11 × 10–15 m3N?1m?1 Knoop microhardness 2230 HK0.010.