A highly compact coating responsible for enhancing corrosion properties of Al-Mg-Si alloy

The formation of a highly compact coating responsible for improvement in corrosion properties of Al-Mg-Si alloy was investigated. In this study, a plasma electrolytic oxidation (PEO) was performed in a citrate-aluminate electrolyte with potassium hexafluorosilicate (K2SiF6), and the results were compared to the counterpart without K2SiF6. The addition of K2SiF6 to the present electrolyte would give rise to the highly compact coating due to the insoluble compounds of SiO2 and AlF3 which were incorporated uniformly throughout the coating. This would lead effectively to superior corrosion-protection properties to the case without K2SiF6.