The impact of LSM pretreatment on the growth behavior, electrical insulation and corrosion resistance properties of PEO coating on 6061 aluminum alloy

This work reported the influence of laser surface melting (LSM) pretreatment on the growth behavior, electrical insulation and corrosion resistance of plasma electrolytic oxidation (PEO) film on 6061 aluminum alloy. It is found that the LSM pretreatment refines the surface structure of original Al metal, generating defects that store excessive energy, thereby enhancing reaction kinetics and phase transition during the PEO process. By LSM pretreatment, uniform electrical discharge and film growth can be obtained, resulting in fewer defects and lower porosity in PEO layers. Additionally, a large amount of columnar crystals comprising of SiO2 phase are observed, which transformed from the SiO32- deposited on the surface, and the LSM pretreatment significantly improves the electrical insulation, corrosion resistance, and substrate adhesion of following PEO layer. Under the same PEO treatment duration, the breakdown voltage of coating increased by 100 V, and icorr decreased from 3.26 x 10-4 to 9.13 x 10- 6 A cm- 2. It is expected that the combination of LSM and PEO processes can not only enhance the surface properties of Al metal, but also expand the practical application of aluminum alloy in high-power electronic devices and related fields.