Effect of Coating Structure on Microstructure and Properties of Cr_2O_3 Coatings

Three kinds of Cr_2O_3 ceramic coating structure,i.e.,two layer,three layer and five layer ceramic coatings were prepared by plasma spraying.Effect of coating structure on the coatings microstructure,bond strength,the thermal schock and wear resistances were investigated.The results show that the multi-layer ceramic coatings can increase the bond strength,and the resistance to thermal shock and wear.Among the three kinds of multi-layer coating,the five-layer coating is the best one.The microstructure observation and the micro-hardness measurement show that the five layer coating has the characteristics of gradient variation,which means that the gradient ceramic coating could be prepared by plasma spraying through gradient change of the composition from the substrate to the surface layer.