Mg-3Zn-0.5Zr合金在含有不同离子的模拟生理环境中的降解机理

Degradation mechanism of the biomedical Mg-3Zn-0.5Zr alloy in a simulated physiological environment containing different an

摘要:

采用电化学测试（极化曲线，开路电位，电化学阻抗谱）研究了Mg-3Zn-0.5Zr合金在四中侵蚀性离子（cl-,HPO42-,HCO3-和SO42-）相互作用下的降解行为。我们发现cl-会导致合金发生多孔状点蚀，腐蚀坑在表面扩展并加深。HPO42-能降低合金降解速率抑制点蚀。Mg-3Zn-0.5Zr合金在含有HCO3-离子的溶液中腐蚀行为是早期HCO3-离子大大加快了镁合金的腐蚀降解速率，但由于能够在剧烈腐蚀部位诱导钝化，对合金点蚀的扩展具有抑制作用。SO42-离子也能腐蚀合金，但在生理环境中浓度低，所以SO42-离子对合金腐蚀降解的行为加速不明显。这些结果加深了我们对Mg-3Zn-0.5Zr合金在生理环境中降解机理的认识。

Abstract:

The interaction and synergetic effects of the four corrosive anions (Cl-, HPO42-, HCO3-, and SO42-) on the degradation behavior of the Mg-3Zn-0.5Zr alloy were investigated using some electrochemical tests, such as potentiodynamic polarization, open circuit potential evolution, and electrochemical impedance spectroscopy (EIS). We found that chloride ions induce porous pitting corrosion on the alloy. The corrosion pits expanded on the surface and much deeper. Hydrogen phosphate ions inhibited the degradation rate and restrained the pitting corrosion. The degradation rate of the Mg-3Zn-0.5Zr alloy was accelerated at early time point during immersed in solutions containing hydrogen carbonate ions. However, precipitation of the magnesium carbonate resulted in passivation and the corrosion products totally inhibited the pitting corrosion. Sulfate ions could also corrode the Mg-3Zn-0.5Zr alloy, but for its low concentration in the physiological environment, the effects of sulfate on the degradation rate and corrosion morphology were limited. All of these results develop our knowledge on the degradation mechanism of Mg-3Zn-0.5Zr alloy in the physiological environment.