铈元素对热浸锌-铝-镁合金镀层显微组织及耐蚀性的影响

摘要

Different amounts of rare earth cerium were added to Zn–Al–Mg bath to improve the properties of hot-dip galvanized Zn–Al–Mg alloy coating,. The effect of Ce content in bath on microstructure and corrosion resistance of the alloy coating was studied by analysis of surface and cross-section morphologies of alloy coating and by neutral salt spray test. With the increasing of Ce content≤0.05wt%in bath, the grain size of Zn–Al–Mg alloy coating obtained from the bath is getting finer and more uniform, the thickness ofδphase remains almost the same, while theζphase becomes slightly thinner. The thickness of alloy phase of coating prepared from the bath containing Ce>0.5wt%is decreased drastically with increasing Ce content. The results of neutral salt spray test showed that the addition of Ce can improve the corrosion resistance of Zn–Al–Mg alloy coating, but should not be more than 0.05%.%在Zn–Al–Mg镀液中添加不同量的稀土Ce以提高热浸镀Zn–Al–Mg合金层性能。通过分析合金镀层的表面形貌和截面形貌以及中性盐雾试验，系统地研究了镀液中 Ce 添加量对合金镀层显微组织结构和耐蚀性的影响。当铈的添加量≤0.05%(质量分数)时，随铈添加量增大，热浸镀Zn–Al–Mg合金层的晶粒逐渐细化，尺寸逐渐均匀；δ相层的厚度变化不大，而ζ相层略微减薄。当铈添加量>0.05%时，随铈添加量增大，镀层合金相厚度骤减。中性盐雾试验表明，镀液中添加Ce有利于提高Zn–Al–Mg合金镀层的耐蚀性，但其添加量不宜超过0.05%。