Preparation of corrosion-resistant hydrophobic composite films on magnesium alloy

Magnesium alloy has attracted wide attention for excellent properties but poor corrosion resistance hinders its application. The method of preparing high-performance corrosion-resistant films with low cost and easy operation is significantly crucial to the corrosion protection of magnesium alloy. By synthesizing zeolite film directly on AZ91D magnesium alloy, the work presented a simple, efficient and environmentally-friendly preparation method. In this study, a one-step synthesis method of multi-structure composite film on AZ91D magnesium alloy was explored. The prepared film surface had dense Mg(OH)2 bottom layer and K2Al2Si4O12·xH2O upper layer with porous support microstructure. Compared with the substrate, the corrosion current on the sample surface modified by stearic acid was reduced by about three orders of magnitude, and the corrosion inhibition rate reached 99.96% with a stable contact angle of about 125°. The results showed the excellent corrosion resistance and stable hydrophobicity of the prepared sample.