Microstructure and tribological properties of TiCN-Al2O3 composite coatings fabricated by reactive plasma spraying

In this paper, TiCN-Al2O3 composite coatings were fabricated by reactive plasma spraying (RPS). The influences of Al2O3 content on the microstructure, phase and composition of composite coatings were investigated. The Vickers microhardness of coatings was tested and the corresponding Weibull distributions were also analyzed. In addition, oxidized and tribological properties of composite coatings were investigated. Results show that all the composite coatings consist of TiC0.7N0.3, TiO2, γ-Al2O3, few α-Al2O3 and/or residual graphite and the amount of TiC0.7N0.3 decreases with the increase of Al2O3 content. Al2O3 particles preferentially distribute at inter-lamellar gaps to improve the microstructural compactness, while a loose structure is formed as the increase of Al2O3 particles. Weibull distribution of Vickers microhardness of all the coatings shows apparent scattering characteristic, while a relatively even distribution is obtained for the coating with 10 wt% Al2O3. Furthermore, the coating with 10 wt% Al2O3 exhibits a better oxidation resistance and wear resistance due to the dense microstructure.