Study of formation mechanism of corrosion resistant oxide films and surface oxidation phenomena of magnesium alloys

“镁的实际重要性是显而易见的，特别是在生态学和环境方面的观点。However，关于氧化物薄膜的微观结构和基本生长机制的足够的信息是可用的。在目前的研究中，纯镁和镁合金对纯镁合金进行了电化学分析、TEM、SEM和表面分析等XPS和GD-OES的研究。镁的电氧化可以成功地实现明亮的表面遵循类似的机制，以实现其铝的发光。当异常电压在碱性解决方案中增加到5V左右时，当前密度可扩展增加。在voltage decreases the current until the voltage reaches to a critical voltage of electric breakdown。关键电压依赖于镁基质的纯度和铝含量。按顺序排列：99.6%，AZ 31，AZ 91和99.95%。Including impurities decrease breakdown voltage while aluminum decreases breakdown voltage.当铝离子被添加到电解质中时，关键的电压也增加了。The presence of small amount of aluminum in either substrate or electrolyte improves the film property by selective deposition of spinel （MgAlイイD22イイD24イD2） in the oxide film。Cylindrical pore结构和屏障层，与Keller的Anodic alumina模型相似，也由直接交叉部门观察证实。在密封异源性薄膜后，将含有硅酸钠、平板类羟基的溶液密封在Pores中之后，类似于密封铝的异源性薄膜，这是一个指标。

The practical importance of magnesium has remarkably increased, especially in ecological and environmental points of view. However, no enough information on the microstructure and fundamental growth mechanism of oxide films on magnesium was available. In the present research, formation behavior of anodic films grown on pure magnesium and magnesium alloys was investigated by electrochemical analysis, TEM, SEM and surface analysis such as XPS and GD-OES. Electropolishing of magnesium can be performed successfully to obtain bright surface following the similar mechanism to that of aluminum. When anodic voltage increases to around 5V in alkaline solutions, a current density extensively increases. Further increase in voltage decreases the current until the voltage reaches to a critical voltage of electric breakdown. The critical voltage is dependent on magnesium substrate purity and aluminum content. It increases in the order; 99.6%, AZ31, AZ91 and 99.95%. Including impurities decrease breakdown voltage while aluminum decreases breakdown voltage. When aluminum ions are added in electrolytes the critical voltage also increases. The presence of small amount of aluminum in either substrate or electrolyte improves the film property by selective deposition of spinel (MgAlィイD22ィエD2OィイD24ィエD2) in the oxide film. The cylindrical pore structure and the barrier layer, which are similar to the Keller's model of anodic alumina, are also confirmed by direct cross-sectional observation. After the sealing of anodic film in a boiling solution containing sodium silicate, platelet-like hydroxides in pores, which are similar to sealed anodic films on aluminum, is indicated.