Effect of adding K2TiF6 and K2ZrF6 to neutral electrolyte on the performance of plasma electrolytic oxidation coatings on AZ91 Mg alloy
Chen Li, Yan Li, Tao Zhang, Fuhui Wang
Abstract
The traditional alkaline electrolyte preparation of plasma electrolytic oxidation (PEO) coating ignites a significant spark, and the increase of micro-defects leads to a decrease in corrosion resistance. In this study, the preparation of PEO coating with neutral electrolyte was studied, and the effects of K2TiF6 and K2ZrF6 doping on the microstructure, phase composition, corrosion resistance and mechanical properties of the coating were explored. It was found that in neutral solution, the size and number of sparks decreased significantly, and the compactness of the coating increased. The phase composition was mainly MgF2. After the addition of K2TiF6 and K2ZrF6, the corrosion current density dropped from 256 to 28 and 61 nA/cm2. The long-term corrosion resistance of the coating was significantly improved. The hardness and adhesion of the coating were significantly improved.