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 250-330oC. 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 270-310oC showed better corrosion resistance than others. In Xray diffraction analysis, ZnMg2 was detected through out the temperature range, whereas Mg2Zn11 and FeZn13were detected only in the film annealed at 310oC. The depth composition profile showed that the compositions of Mg at 270-290oC are evenly and deeply distributed in the film surface layer. These results demonstrate that 270-290oC is a proper temperature range to produce a layer of MgZn2 intermetallic compound to act as a homogeneous passive layer. KCI Citation Count: 0