Microstructure and properties of in-situ composite coatings prepared by plasma spraying MoO3–Al composite powders

Abstract

MoO3–Al composite powders were used for preparing in situ composite coatings. Effects of the composition of MoO3–Al composite powder on the microstructure and properties of the as-prepared coatings were investigated. The results show that the main phases of the as-prepared coatings were γ-Al2O3 and Mo. An optimal composition (63 wt%) of MoO3 in MoO3–Al composite powder was demonstrated. The porosity of the as-prepared composite coatings decreased first and then increased with the increase of MoO3. This is attributed to the fact that the melting state of the powder during plasma spraying is closely involved in the content of MoO3. The coating prepared by composite powder with 63 wt% MoO3 had the most Al2O3 and the highest microhardness. The wear resistance of 63 wt% MoO3 composite coating was the best among four coatings with different content of MoO3, which is attributed to its high hardness and good toughness.