Tribological performance of plasma sprayed Al2O3-Y2O3 composite coatings

In the present study, Al2O3 and Al2O3-Y2O3 composite coatings were deposited by atmospheric plasma spraying. The microstructure, hardness, thermal conductivity and dry sliding wear behavior of the coatings were examined. The results showed that the mass ratio of α-Al2O3/γ-Al2O3 in as-sprayed Al2O3 coating was 0.08. However, the corresponding value in Al2O3-Y2O3 composite coating was 0.53. This exhibits salient influence on the stabilization of α-Al2O3. The addition of Y2O3 was beneficial to improve the thermal conductivity of the composite coating. In addition, Al2O3-Y2O3 composite coating/graphite pairs possess more stable friction coefficients, which may be related to the formation of more effective and stable graphite transferred film on the surface of the coating subjected to abrasion. Further, the wear resistance of Al2O3-Y2O3 composite coatings was superior to that of Al2O3 coatings.