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在Na2SiO3和NaAlO2为主成膜剂的硅铝复合电解液中,利用交流脉冲电源对AZ91D镁合金进行微弧氧化处理,研究主成膜剂含量的变化对微弧氧化过程及膜层特性的影响规律。利用扫描电镜(SEM)和膜层测厚仪分别研究了膜层的微观形貌和膜层厚度,通过电化学阻抗谱(EIS)测试膜层在3.5%NaCl中性溶液中的耐蚀性能。结果表明,随着主成膜剂含量的增加,微弧氧化过程中起弧电压和终止电压均呈下降的变化趋势,而膜层耐蚀性则基本呈先增大后降低的变化趋势,膜厚的变化趋势与其耐蚀性一致;Na2SiO3含量的变化对膜层内部致密层和外部疏松层的耐蚀性均有影响,而NaAlO2含量的变化则主要影响膜层内部致密层的耐蚀性;适量的主成膜剂含量是获得致密耐蚀膜层的关键。
In the silicon-aluminum composite electrolyte containing Na2SiO3 and NaAlO2 as main film-forming agent, the AZ91D magnesium alloy was treated with MAO by AC pulse power to study the effects of the content of the main filming agent on the micro-arc oxidation process and film properties law. The microstructure and film thickness of the film were studied by scanning electron microscope (SEM) and thickness gauge. The corrosion resistance of the film in 3.5% NaCl neutral solution was tested by electrochemical impedance spectroscopy (EIS). The results show that with the increase of the content of the main filming agent, the arc starting voltage and the final voltage decrease with the increasing of the content of main filming agent, while the corrosion resistance of the film increases first and then decreases. The change trend of thickness is consistent with the corrosion resistance. The change of Na2SiO3 content affects the corrosion resistance of the inner dense layer and the outer loose layer, while the change of NaAlO2 content mainly affects the corrosion resistance of the inner dense layer. The right amount of main film-forming agent is the key to obtain a dense corrosion-resistant coating.