Study on Properties of Pure Al Coatings and Al/SiC Composite Coatings by Plasma Transferred Wire Spraying

Abstract

Normally, aluminum-based (Al-based) anti-corrosion coatings are prepared by flame spraying and other coating technologies to improve the corrosion resistance of metal materials in the marine environment. However, the prepared coatings are usually found to be poor in quality owing to the shortcomings of traditional thermal spraying technologies, such as flame spraying, including the low jet temperature and low particle in-flight velocity. In this paper, pure Al coatings and Al/SiC composite coatings were prepared on the surface of low-carbon steel by innovatively adopting plasma transferred wire spraying technology and making full use of the technological advantages of plasma spraying. In addition, the experiments have shown that larger SiC particles play a role in shot peening during the spraying process, allowing Al droplets to spread and overlap more fully, effectively improving the density of the coating and reducing defects such as pores and cracks in the coating. However, there is no significant effect on improving the bonding strength of the coating. Therefore, the porosity of pure Al coating and Al/SiC composite coating is 3.9% and 2.5%, respectively; the microhardness is 36 HV_0.1 and 102 HV_0.1, respectively, increasing by about three times; the bonding strength with the matrix is 39.0 and 36.5 MPa, respectively; the corrosion resistance of Al/SiC composite coating is significantly better than that of pure Al coating, and the wear rate is reduced by 7 times compared to pure Al coating.