Effects of Triethanolamine on Microstructure and Properties of Anodized Films on AZ31 Magnesium Alloy

The effects of triethanolamine concentration on the microstructure and corrosion resistance of the anodized films on AZ31 magnesium alloy were studied by scanning electron microscopy, optical microscopy, X-ray diffraction and salt-spray testing. The results show that after addition of triethanolamine, the sizes of micro-pores in the anodized films of AZ31 magnesium alloy became smaller, the structure became more compact, and the thickness of anodized films increased. Triethanolamine had no significant effect on the phase structure of anodized films on AZ31 magnesium alloy, and the anodized films on AZ31 magnesium alloy were all consisted of MgO phase and Mg₂SiO₄ phase. The corrosion resisitance of anodized films was improved by the addition of triethanolamine, and the anodized films on AZ31 magnesium alloy with 30 g/L triethanolamine had better corrosion resistance. The improvement of corrosion resistance was related to the pore size and compactness of the anodized films.