Influence of transitive materials on Al₂O₃ gradient ceramic coatings prepared by plasma spraying

According to the fact that Al₂O₃ ceramic coatings have low adhesion strength and high porosity, two kinds of Al₂O₃ gradient ceramic coatings using NiAl intermetallic compound and Cu powders as transitive materials respectively were prepared by plasma spraying, and the microstructure of gradient coatings was observed, and the adhesion strength and porosity of the coatings were tested and analyzed.The results indicate that the gradient coatings show that the characteristic of structure is not uniform macroscopically but consecutive microscopically.NiAl intermetallic compound and Cu are ideal transitive materials between metal matrix and Al₂O₃ coatings, which can improve the adhesion strength of the coatings efficiently. The adhesion strength of Cu-Al₂O₃ gradient coatings is higher than that of NiAl-Al₂O₃ gradient coatings.The porosity of gradient coatings is lower than that of double layer coatings.The porosity of Cu-Al₂O₃ gradient coatings decreases as the Al₂O₃ content increases, and it is lower than that of NiAl-Al₂O₃ gradient coatings.