Mn、Ti对热浸镀Zn-5Al合金镀层组织与耐蚀性的影响

摘要

采用扫描电镜(SEM),能谱仪(EDS)、电化学测试等手段研究了Mn、Ti对热浸镀Zn-5Al合金镀层组织与耐蚀性的影响.结果表明:Zn-5Al-0.2Mn和Zn-5Al-0.15Ti合金镀层的腐蚀速率分别为Zn-5Al合金镀层的44.8％和39％;在Zn-5Al合金镀层中添加Mn、Ti,促进了Al在过渡区的集聚,使含Fe2 Al5过渡层的厚度增大;添加Mn使Zn-5Al合金镀层中的共晶组织细化,而添加Ti则使共晶组织粗化,但此时共晶Al相已与钢基体连续融合;Zn-5Al-0.2Mn和Zn-5Al-0.15Ti合金镀层的自腐蚀电流密度均比Zn-5Al合金镀层的小,具有更好的耐蚀性.%Effects of Mn and Ti on the microstructure and corrosion resistance of hot-dip galvanized Zn-5Al alloy coatings were investigated by scanning electron microscopy (SEM),energy dispersive spectroscopy (EDS) and electrochemical testing.The results indicate that the corrosion rates of Zn-5Al-0.2Mn and Zn-5Al-0.15Ti alloy coatings were 44.8％ and 39％ of that of Zn-5Al alloy coating,respectively.The addition of Mn and Ti in Zn-5Al alloy coating promoted the agglomeration of Al in transition zone,and increased the thickness of the transition layer containing Fe2 Al5.The eutectic structure in Zn-5Al alloy coating was refined by additing Mn,and was coarsened by additing Ti,but the eutectic Al phase was continuously fused with the matrix of steel at this time.The Zn-5Al-0.2Mn and Zn-5Al-0.15Ti alloy coatings had smaller corrosion current densities than the Zn-5Al alloy coating,showing better corrosion resistance of the former.