Effects of Al2O3 content on the microstructure and performance of Inconel 625-xAl2O3 composite non-skid coatings by plasma enhanced high-velocity arc spraying

Abstract

The efficient preparation of metal/ceramic composite coatings with excellent performance has been a hot research topic in the field of thermal spraying. In this study, a novel plasma enhanced high-velocity arc spraying (PE-HAS) technique is developed. A series of Inconel 625-xAl2O3 composite non-skid coatings are deposited by PE-HAS with different feeding ratio of alloy wire (1.6 mm in diameter) and ceramic powder (13.5 μm in average particle size). Specifically, the microstructure, mechanical properties, corrosion resistance and tribological performances of the coatings have been comprehensively investigated. Results indicate that all of the composite coatings with different Al2O3 contents are characterized by high densities, low defects (porosity≤3.52 %), strong bonding (≥50 MPa) and high friction coefficient (≤ 1.034). The coatings with low Al2O3 content feature a more homogeneous structure and superior bonding strength. The microhardness and wear resistance of the coatings increases significantly with increasing Al2O3 content, which should be attributed to the formation of many localised enhancement areas composed of different forms of Al2O3 phases. It is worth noting that the unique feedstock feeding method promotes the formation of the in-situ double-layer structure of coatings with high Al2O3 content, which further improves the wear and corrosion resistance. However, the friction coefficient gradually decreases when the Al2O3 content is too high, thus affecting the anti-slip performance of the coating.