热浸镀时间对含稀土的锌基合金镀层耐蚀性的影响

Effect of hot-dip coating time on corrosion resistance of rare-earth-containing zinc alloy coating

研究了500℃下不同热浸镀时间对Zn-11%Al-3%Mg-0.2%Si-0.02%RE合金镀层中元素分布和物相组成的影响,利用动电位极化法和电化学阻抗谱测试了镀层的耐腐蚀性能。结果表明,热浸镀30 s的镀层中Al、Zn的含量高于热浸镀60 s的镀层,而随着热浸镀时间的延长,主要由Zn、Fe_(4)Zn_(9)、MgZn_(2)、Al_(5)Fe_(2)等物相组成的中间过渡层在整个镀层中所占的比例增加。与热浸镀60 s的镀层相比,热浸镀30 s的镀层虽更薄,但更致密,因而具有更好的耐蚀性。

The effect of hot-dip coating time at 500℃ on the element distribution and phase constitution of a Zn-11%Al-3%Mg-0.2%Si-0.02%RE alloy coating was studied.The corrosion resistance of the coating was tested by potentiodynamic polarization measurement and electrochemical impedance spectroscopy(EIS).The results showed that the contents of Al and Zn in the coating prepared at 500℃ for 30 s were higher than that of the one prepared at the same temperature for 60 s.The proportion of the intermediate layer,which was mainly composed of Zn,Fe_(4)Zn_(9),MgZn_(2),and Al_(5)Fe_(2),in the whole coating was increased with the extending of hot-dip coating time.The coating prepared at 500℃ for 30 s was thinner but more compact than the one prepared at 500℃ for 60 s,and therefore it had better corrosion resistance.