Exploring the Tribophysics and Tribochemistry of MoS2 by Sliding MoS2/Ti Composite Coating Under Different Humidity

The MoS2 coatings were prepared by unbalanced magnetron sputtering system. Ti was used as the dopant to improve its mechanical properties and oxidation resistance. The microstructure of the coatings changed from coarse columnar platelet structure at low Ti content (0–1.8 at.%) to a denser columnar microstructure at increased Ti content. The hardness and elastic modulus of the MoS2/Ti composite coatings gradually increase as the Ti content increases. The tribological properties of the coatings were evaluated against a GCr15 ball under different relative humidity atmosphere to verify the oxidation resistance. The results show that doping of Ti can significantly improve the oxidation resistance of the coatings. Particularly, the friction coefficient for the composite coating with 10.8 at.% Ti exhibited almost the same friction coefficient under three different humidity. However, excessive Ti induced high brittleness and the coatings flaking easily from the substrate; therefore, the coatings show poor wear resistances under both dry and humidity atmospheres.