Corrosion and electrochemical behavior of Zn-Cu-Ti alloy added with La in 3% NaOH solution

The corrosion mechanism of Zn-Cu-Ti alloy added with La in 3% NaOH solution was investigated by electrochemical testing and SEM observation. Polarization curves manifested that the overall corrosion kinetics of alloys are under anodic control. The anodic passivation of the Zn-Cu-Ti alloy is remarkably improved by the addition of La. Because La can effectively improve the hydrogen evolution/oxygen reduction over-potential of alloy elements, and the rare earth oxide film plays an important role in insulation that can strengthen the dielectric properties of Zn-Cu-Ti alloy, the corrosion resistance of Zn-Cu-Ti alloy is made significantly better by adding a trace amount of La. The improvement of corrosion resistance is not positively correlated with the adding amount of La to alloy. The Zn-Cu-Ti-0.5La alloy displays the best corrosion resistance behavior. The corrosion form of the alloys mainly belongs to a selective corrosion and the main solid corrosion products are Zn(OH)2 and ZnO.