Influences of tannic acid concentration on properties of micro-arc coatings formed on AZ91 magnesium alloys

摘要

Anodic coatings were prepared by micro-arc oxidation on AZ91 magnesium alloys with the addition of 0-8 g/L tannic acid. The influences of tannic acid concentration on the conductivity and coating properties were studied. The result shows that with the increase of tannic acid concentration, the solution conductivity decreases and the coating color becomes dark. In the solution with 4 g/L tannic acid, the obtained coatings are the most uniform and achieve the best corrosion resistance.