摘要
在室温下,将Mg-0.5Ca合金在不同浓度的氢氧化钠和HF溶液浸渍不同的时间,研究HF处理对合金腐蚀行为的影响。采用原子力显微镜、X射线衍射、场发射扫描电子显微镜表征样品的微观组织变化。通过动电位极化和Kokubo溶液浸泡试验测试样品的耐腐蚀性。结果表明,与35%HF处理的样品相比,经40%HF溶液处理的Mg-0.5Ca合金具有更均匀、更致密、更薄的涂层(12.6μm)。电化学测试表明,在Kokubo溶液中,经氟化物处理的Mg-0.5Ca合金样品的耐腐蚀性比未处理样品的高35倍;前者的体外降解速率远远低于后者的。在40%HF溶液处理过的样品表面只出现了一些腐蚀点,而未经处理的样品完全被腐蚀产物覆盖且出现了分层现象。40%HF处理的Mg-0.5Ca合金,具有低的降解速率和良好的生物相容性,是一种有潜力的植入材料。
The influence of hydrofluoric acid（HF） treatment on the corrosion behavior of the Mg-0.5Ca alloys was investigated by immersion specimen in sodium hydroxide and HF solutions with various concentrations and durations at room temperature.Microstructural evolutions of the specimens were characterized by atomic force microscopy,X-ray diffraction,field-emission scanning electron microscopy.The corrosion resistance was examined through potentiodynamic polarization and immersion test in Kokubo solution.The results revealed that the fluoride treated Mg-0.5Ca alloys produced by immersion in 40% HF provided more uniform,dense and thicker coating layer（12.6 μm） compared with the 35% HF treated specimen.The electrochemical test showed that the corrosion resistance of fluoride treated specimen was 35 times higher compared with the untreated Mg-0.5Ca alloy specimen in Kokubo solution.In vitro degradation rate of the fluoride treated specimens was much lower than untreated Mg-0.5Ca alloy in Kokubo solution.After immersion test the surface of 40% HF treated sample showed a few corrosion dots,while untreated specimens were fully covered by corrosion products and delamination.Fluoride treated Mg-0.5Ca alloy with 40% HF is a promising candidate as biodegradable implants due to its low degradation kinetics and good biocompatibility.
基金
supported financially by Ministry of Higher Education of Malaysia under the Vote Number 78610
