Due to their much lower surface roughness compared to that of microcrystalline diamond, nanocrystalline diamond (NCD) films are promising candidates for tribological applications, in particular when deposited on hard ceramic materials such as silicon nitride (Si 3 N 4). In the present work, microwave plasma-assisted chemical vapour deposition of NCD is achieved using Ar/H 2 /CH 4 gas mixtures on plates and ball-shaped Si 3 N 4 specimens either by a conventional continuous mode or by a recently developed pulsed regime. The microstructure, morphology, topography and purity of the deposited films show typical NCD features for the two kinds of substrate shapes. Besides, tribological characterization of the NCD/ Si 3 N 4 samples is carried out using self-mated pairs without lubrication in order to assess their friction and wear response. Worn surfaces were studied by SEM and AFM topography measurements in order to identify the prevalent wear mechanisms. Friction values reached a steady-state minimum of approximately 0.02 following a short running-in period where the main feature is a sharp peak which attained a maximum around 0.44. Up to the critical load of 35 N, corresponding to film delamination, the equilibrium friction values are similar, irrespective of the applied load. The calculated wear coefficient values denoted a very mild regime (K ∼ 1 × 10 − 8 mm 3 N − 1 m − 1) for the self-mated NCD coatings. The predominant wear mechanism was identified as self-polishing by micro-abrasion.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.