2006 年 57 巻 1 号 p. 84
The corrosion resistance of Zn-Mg alloy plated steel prepared by the electrodeposition from 1-ethyl-3-methylimidazolium bromide (EMIB) based ionic liquid was investigated in 5mass% NaCl aqueous solution at 35ºC. The first red rust generation time of Zn-Mg alloy plated steel containing more than 2.5mol% of Mg was about 20 weeks independently of the Mg content. The corrosion resistance of Zn-Mg alloy plated steel was about 20 times higher than that of Zn plated steel. The excellent corrosion resistance of the Zn-Mg alloy plating is due to the fact that the fine and insulating initial corrosion product ZnCl2•4Zn(OH)2•H2O is formed on the Zn-Mg alloy plating and Mg suppresses the cathodic reaction of corrosion and the formation of ZnO, which causes the corrosion of plating and steel. As a result, the effect of sacrificial protection of the Zn-Mg alloy for steel continues for a long time, and the corrosion resistance is improved.