AZ91镁合金表面热浸镀Zn-4%Al-1%Sb合金层的状况及Al,Sb的作用

Corrosion Resistance of Hot-dipping Zinc-Aluminum-Antimony Alloy Coating on the Surface of Magnesium Alloy

与其他表面处理方法相比,AZ91镁合金表面热浸镀Zn-4%Al-1%Sb合金层工艺简单、费用低,且又能提高其耐蚀性。采用扫描电镜观察和能谱分析研究了AZ91镁合金表面热浸镀Zn-4%Al-1%Sb合金镀层。结果表明:AZ91镁合金预热温度为200℃,Zn-4%Al-1%Sb合金液温度为420℃,浸镀时间为6 s时,能获得较光滑的镀层;且在AZ91镁合金和Zn-4%Al-1%Sb合金中含有Mg,Zn,Sb,Al元素,其主要为Mg2Zn3,Mg3Sb2,Mg17Al12化合物,冶金结合效果良好,镀层的耐腐蚀性能明显提高;Sb元素的加入能在一定程度上减缓锌合金液与基体的反应。

Zn-4%Al-1%Sb(mass fraction) alloy coating was prepared on the surface of AZ91 Mg alloy by hot-dipping so as to improve the corrosion resistance.The morphology,elemental composition and phase structure of the hot-dipping alloy coating were analyzed by means of scanning electron microscopy,energy dispersive spectrometry and X-ray diffraction.Results indicate that smooth Zn-4%Al-1%Sb alloy coating can be prepared on the surface of AZ91 Mg alloy by 6 s of hot-dipping while the pre-heating temperature of the Mg alloy is adjusted as 200 ℃ and the temperature of the hot-dipping solution as 420 ℃.As-obtained alloy coating consisting of Mg2Zn3,Mg3Sb2 and Mg17Al12 is well combined with the Mg alloy substrate via desired metallurgical bonding,thereby significantly improving the corrosion resistance of the Mg alloy.Moreover,introducing Sb into the hot-dipping solution favors to retard the reaction between the solution and Mg alloy substrate.