Effect of laser-assisted irradiation on the characteristics and corrosion behavior of plasma electrolytic oxidation ceramic coating on AZ31B magnesium alloy

The Laser/PEO ceramic coating was successfully prepared in situ on AZ31B magnesium alloy by laser-assisted PEO (Laser/PEO) composite process. SEM, EDS, CLSM, XRD, XPS and M - S tests were used to observe the effects of different laser power densities on the morphology, chemical composition and electronic properties of PEO ceramic coating. The corrosion behavior of PEO ceramic coating (S0) and Laser/PEO ceramic coating (S1) was systematically observed by PDP test, EIS test, SEM, EDS, XRD and XPS by long-term immersion experiments (24, 96, 168 h) in 3.5 % NaCl solution. Moreover, the effect of laser-assisted irradiation on the corrosion mechanism of PEO ceramic coating was discussed. The Laser/PEO coating (S1) possessed better long-term corrosion resistance than PEO coating (S0), which was attributed to the improvement of laser-assisted irradiation on the density, crystallinity, thickness, and corrosion-resistant phase proportion and distribution of PEO coating.