Mg-2Zn-0.5Ca-Y系列镁合金在模拟体液和氯化钠溶液中的腐蚀行为和电化学性质（英文）

Corrosion Behavior and Electrochemical Properties of As-cast Mg-2Zn-0.5Ca-Y Series Magnesium Alloys in Hank's Solution and NaCl Solution

利用金相显微镜和扫描电镜观察Mg-2Zn-0.5Ca-Y系列镁合金的金相结构及表面微观形貌,使用电化学测试系统测试铸态Mg-2Zn-0.5Ca-Y系列镁合金在模拟体液和3.5%Na Cl溶液中的电化学腐蚀性能,通过在模拟体液和3.5%Na Cl溶液中的浸泡试验测试其腐蚀速率。Mg-2Zn-0.5Ca-Y系列镁合金的微观腐蚀形貌表明,腐蚀并不均匀,在浸泡试验后其腐蚀表面有大量的裂纹。稀土Y的加入能够提高其耐蚀能力,并且Mg-2Zn-0.5Ca-1.0Y合金的耐蚀性优于其他同系合金。由于腐蚀保护层的存在,所有在模拟体液和氯化钠溶液中得到的极化曲线均显示出高容电流。在实验条件下的电化学阻抗曲线均仅有一个循环电容。出现高频率的循环电容是由于稳定的双电层电容的存在。出现低频率的循环电容是由于自由区域的扩散控制膜。

Microstructure and bio-corrosion behavior of as-cast Mg-2Zn-0.5Ca-Y series alloys were investigated for biomedical application by optical microscopy, scanning electronic microscopy（SEM）, immersion tests and electrochemical measurements in Hank＇s solution and Na Cl solution（3.5wt%）. The morphologies of the Mg-2Zn-0.5Ca-Y series magnesium alloys indicate that the corrosion is not uniform and a lot of cracks are formed on the surface of the corrosion layer after immersion tests. The corrosion resistance of as-cast Mg-2Zn-0.5Ca-Y series alloys increases owing to the addition of the rare earth element Y and that of Mg-2Zn-0.5Ca-1.0Y alloy is the best. All of the potentiodynamic polarization curves obtained in the tests in Hank＇s solution and Na Cl solution show current plateaus which are due to the presence of a protective corrosion product film. The electrochemical impedance curves of the alloys in the test solutions have only one capacitive loop. The appearance of a capacitive loop at high frequency is caused by the stable double-layer capacitance. The capacitive loop at low frequency is attributed to diffusion control at film-free areas.