Abstract
The environmental friendly anodizing was carried out using a mainly phosphate solution without heavy metal onto AZ91D magnesium alloy. The effects of the anodizing on mechanical properties were examined using a tensile test and hardness tester. The tensile test revealed that the anodic oxide coatings less than 10 μm in thickness appear not to lower the tensile strength. The hardness of AZ91D substrate with the coatings less than 10 μm in thickness after anodizing increased, and this tendency was remarkably recognized near the surface. This surface hardening is considered to be due to the rise in the temperature of the specimen of surface side and the resulting solution treatment brought by dielectric breakdown during anodizing. These results demonstrate the advantage of this anodizing for the application of the structural material in such as the automotive field.
