Mechanical and tribological performance of MoS2 co-sputtered composites

Co-sputtered films of MoS2 with Au, Ti, Cr or WSe2, respectively, have been deposited in order to investigate the relationships between dopant and tribological and mechanical behaviour. The alloying constituents were selected based on possible chemical effects, for example substitution in the MoS2 structure, intercalation, edge-bond passivation, and with and without simultaneous oxygen gettering of the sputtering environment. The mechanical properties of the composite films were investigated by pin-on-disk sliding wear testing and linear, oscillating wear testing both in 50% relative humidity air, microscratch and indent adhesion characterisation, and nanoindentation hardness as a function of the dopant element(s) and concentration. All of the dopants investigated exhibited superior tribological and mechanical behaviour compared to the pure MoSx films. In tribological tests, results indicate a significant improvement in the lifetime, mean friction coefficient, and friction ‘noise’ of the films. Tribological performance was found to be strongly related to both the dopant element and dopant concentration. The best dopant for improved performance was found with WSe2 followed by Au, Ti, and Cr.