Influence of SiC nanoparticles on microstructure and corrosion behavior of microarc oxidation coatings formed on TC4 alloy

A microarc oxidation (MAO) coating was fabricated on the surface of TC4 alloy by adding SiC nano-particle into the base electrolyte. The influence of nanoparticles on the microstructure and corrosion behavior of MAO coatings was investigated. The results show that the introduction of SiC nanoparticles into the base electrolyte makes the coating thickness of MAO coating increased, from 9.2, 12.8, 12.4μm to 12.0, 14.9, 20.0μm, respectively, under the conditions of 550, 600V and 650V. The surface roughness of the coating (2.65, 3.34μm and 3.61μm) fabricated in SiC-containing solution increases with increasing the applied voltage. The introduction of SiC nanoparticles can effectively inhibit the microcracks in the coating, the coating thickness increase, and reduce the anodic current density, and thus the corrosion property of MAO coating increases. The OCP(open circuit potential) and corrosion potential increase by MAO coating.