Improved Corrosion Behavior of Biodegradable Mg-4Zn-1Mn Alloy Modified by Sr/F co-doped CaP Micro-arc Oxidation Coatings

The Sr/F co-doped CaP(Sr/F-CaP)coatings were prepared by micro-arc oxidation(MAO)under different voltages to modify the microstructure and corrosion behavior of Mg-4Zn-1Mn alloy.The surface and interface characteristics investigated using scanning electron microscopy(SEM)and energy dispersive X-ray spectrometer(EDS)showed that the MAO coatings displayed uneven crater-like holes and tiny cracks under lower voltage,while they exhibited relatively homogeneous crater-like holes without cracks under higher voltage.The thickness of MAO coatings increased with increasing voltage.The corrosion behavior of Mg-4Zn-1Mn alloy was improved by the MAO coatings.The MAO coatings prepared under 450 V and 500 V voltages possessed the best corrosion resistance with regard to the electrochemical corrosion tests and immersion corrosion tests,respectively.The MAO coatings fabricated under 450-500 V could provide a better corrosion protection effect for the substrate.

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

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。