A Comparison Study on Wear Behaviors of Mo and Al2O3-Mo Coatings from RT to 300 °C

Mo and Al2O3-Mo coatings are fabricated on a low-carbon steel substrate using atmospheric plasma spraying. The microstructure and mechanical properties of two as-sprayed coatings, with a particular focus on the tribological behaviors from room temperature to 300 °C, are comparatively investigated in this study. Microstructural analysis of the coatings shows that the porosity of the Al2O3-Mo coating is higher than that of Mo coating. The addition of Al2O3 particles reduces the coating–substrate adhesion strength. The Al2O3-Mo coating, in comparison to the Mo coating, shows improved mechanical properties, such as hardness and wear resistance. The friction coefficients of both coatings increase with further increases in test temperatures. The friction coefficient of the Al2O3-Mo coating, tested above 100 °C, is lower than that of the Mo coating. The wear failure mechanisms of the two coatings are delamination, brittle fracture, oxidation and adhesion wear. In addition, local plastic deformation was also found in the Mo coating.