Ionic liquid-based electrodeposition of ZnS:nano-MoS2 composite films with self-lubricating properties

An innovative protocol to electrodeposit ZnS:nano-MoS2 composite coatings with enhanced tribological properties is reported. The mechanisms involved in the deposition process are analyzed by cyclic voltammetry. The morphology and composition of the ZnS:nano-MoS2 composite coatings are characterized. The tribological performance of the coatings is studied through pin-on-disk tests. The chemical composition of the wear tracks are characterized in order to gain further insight into the mechanisms behind of the self-lubricating ability of the ZnS:nano-MoS2 coatings. Key role for not only MoS2 –i.e. lubricating ability-, but also ZnS as a relatively soft matrix –i.e. providing supplementary sulphur to the MoS tribofilm formation- is suggested. The ZnS:nano-MoS2 composite coatings deposited from 10 g/L MoS2 nanoparticle electrolytes exhibit decreased and stable pin-on-disk friction coefficient of approximately 0.1 under 2 N of normal load.