镁表面改性及其在仿生体液中的耐蚀行为

Surface modification on magnesium by alkali-heat-treatment and its corrosion behaviors in SBF

对纯度为99.9%的纯镁表面改性,以提高纯镁在仿生模拟体液(SBF)中的耐腐蚀性能。其过程为:室温下将纯镁在初始pH值为9.3的过饱和NaHCO3 MgCO3混合溶液中浸泡24h,然后在773K保温10h;再将试样放入(37±0.5)℃的SBF溶液中浸泡14d。X射线衍射分析表明:纯镁在NaHCO3 MgCO3混合溶液中浸泡后,表层主要为MgCO3·3H2O晶体;热处理后,MgCO3·3H2O晶体转变成MgCO3和Mg(OH)2的混合物。EDS分析表明,距表面厚约20μm的基体被氧化,形成了耐蚀氧化层。经碱热处理的试样在SBF溶液中浸泡14d后,经X荧光能谱(XPF)分析可知表层沉积出Ca/P摩尔比为1.858的钙磷基沉淀。本阶段实验表明,碱热处理可以显著提高纯镁在仿生环境下的耐腐蚀性能。

The surface modification on magnesium(99.9%) was carried out to improve its corrosion resistance in simulated body fluid(SBF) solution. Pure magnesium specimens were first treated in supersaturated NaHCO_3-MgCO_3 mixed solutions(SNSM) at room temperature, and then heat-treated at 773 K for 10 h; finally, the corrosion resistance of the samples was tested in SBF solution. The X-ray diffraction(XRD) analysis shows that the coatings obtained on the samples after being treated in SNSM solution is mainly composed of MgCO_3·3H_2O. More important, EDS analysis shows that a magnesium oxide layer with thickness of 20 μm is formed after heat treatment. Ca-P based depositions with molar ratio of 1.858 are detected on the modified specimens after they are immersed in SBF for 14 days. It can be concluded that the coating obtained through alkali and heat treatment could effectively protect magnesium from corrosion in the simulated biological environment.