镁对热浸镀锌铝合金层耐蚀性的影响

摘要

采用热浸镀法在一定的助镀条件下制备了不同镁含量的Zn-Al-Mg合金镀层.利用扫描电镜、能谱仪及X射线衍射仪(XRD)分析了镀层的组织结构；采用NaCl溶液全浸试验和电化学试验评价镀层的耐蚀性能.结果表明,在一定范围内,随着镀液中镁含量的增加,镀层组织更加均匀、致密,镀层耐蚀性能也随之提高；当镀液中加入0.7％镁时制备的镀层耐蚀性最好,超过0.7％时镀层的耐蚀性能反而下降.%Zn-Al-Mg alloy coatings with different magnesium contents were prepared by hot dip method.Microstructures and compositions of the coatings were studied by SEM,EDS and XRD.NaCl solution immersion test,electrochemical thermal shock test were used to study the corrosion resistance of the coatings.The results show that the increasing of Mg contents can make the coating morphology more uniform and dense,improve the corrosion resistance in a certain range.Zn-Al-Mg alloy coatings with Zn-5％ Mg-0.7％,showed the best corrosion resistance,the corrosion resistance became worse when the Mg content was beyond 0.7％.