Influence of Annealing Temperatures on Corrosion Resistance of Magnesium Thin Film-Coated Electrogalvanized Steel

To improve the corrosion resistance of an electrogalvanized steel sheet, we deposited magnesium film on it using a vacuum evaporation method and annealed the films at . The zinc-magnesium alloy is consequently formed by diffusion of magnesium into the zinc coating. From the anodic polarization test in 3% NaCl solution, the films annealed at showed better corrosion resistance than others. In X-ray diffraction analysis, was detected through out the temperature range, whereas and were detected only in the film annealed at . The depth composition profile showed that the compositions of Mg at are evenly and deeply distributed in the film surface layer. These results demonstrate that is a proper temperature range to produce a layer of intermetallic compound to act as a homogeneous passive layer.