Effect of La₂O₃ on Microstructure and Properties of Al₂O₃-13%TiO₂ Coating Prepared by Plasma Spraying

The ceramic coatings of Al2O3-13wt%TiO2(AT13) and AT13 with different contents of La2O3 were prepared by atomosphere plasma spraying. Microstructure of the coatings were analyzed by XRD and SEM. The microhardness distribution was studied by normal and Weibull statistical analysis, dry sliding friction and wear behavior was investigated by a friction and wear testing machine in a pin-on-ring mode. The results indicate that the addition of La2O3 improved the combination between splats in the coating and did not result in the change of constitute phase in the coating. The addition of La2O3 had no obvious effect on the microhardness, but reduced the scatter of microhardness distribution in the coating, the wear resistance of AT13 coating with the addition of La2O3 was evidently enhanced. The best wear resistance of the coating and the minimum scatterness of microhardness data were obtained when the content of La2O3 was 6wt%. The wear mechanism was predominantly attributed to the brittle spalling and adhesive wear.