铝酸钠浓度对镁微弧氧化膜组织与性能的影响

Effects of NaAlO_2 Concentration on Microstructure and Performance of Micro-Arc Oxidation Coatings Formed on Magnesium

在NaAlO2溶液中于恒压条件下对镁进行了微弧氧化处理,研究了NaAlO2浓度对微弧氧化膜表面形貌、相组成和表面硬度的影响,并对不同NaAlO2浓度下所得的微弧氧化膜的耐蚀性进行了表征.结果表明:随着NaAlO2浓度的升高,微弧氧化膜表面的孔洞明显减少,致密性增强,表面硬度显著提高;微弧氧化膜主要由MgO和MgAl2O4相组成,随着NaAlO2浓度的升高,MgAl2O4相所占的比例逐渐增大;在质量分数为3.5%的NaCl溶液中,随NaAlO2浓度升高,所得微弧氧化膜的腐蚀电位逐渐增高,表明耐蚀性逐渐增强,与未处理的试样比较,其耐蚀性有较大提高.

Ceramic coatings were fabricated on magnesium by micro-arc oxidation （MAO） under constant potential in NaAlO2 solution, and the effects of NaAlO2 concentration on the surface morphologies, phase composition and surface hardness of the MAO coatings were investigated. Corrosion resistance of the coatings in different NaAlO2 concentrations and the untreated magnesium were evaluated with the potentiodynamic polarization tester. The results show that with increasing NaAlO2 concentration the micro-pores of MAO coating decrease, while the average surface hardness increases. The MAO coating is mainly composed of MgO and MgAl2O4, and the content of MgAl2O4 increases with the increasing NaAlO2 concentration. With NaAlO2 concentration increasing, the corrosion potential of the MAO coating in 3. 5% NaCl solution increases. MAO coating enables to effectively improve the corrosion resistance of magnesium.