Effect of Mo on tribological behaviors of atmospheric plasma sprayed Al2O3-13%TiO2/Mo coatings under boundary lubrication condition

The role of Mo alloy element on the tribological behaviors of AT13/Mo coatings sliding against Si3N4 balls under boundary lubrication condition was investigated. The results revealed that the AT13 and AT13/Mo coatings were mainly composed of γ-Al2O3, α-Al2O3 and TixOy ceramic phases and both coatings underwent a transition from boundary lubrication to dry friction. Furthermore, the addition of Mo could greatly reduce friction. Moreover, the tribological properties of AT13/Mo coating under boundary lubrication condition were superior over those of pure AT13 coatings. According to XPS results, Mo has undergone a chemical reaction to generate a tribofilm covering the friction interface under boundary lubrication condition, and the film containing MoS2 and MoO2 can greatly enhance load-bearing capability and provide good boundary lubrication effect.