采用等离子体电解氧化(PEO)工艺在Mg-9Gd-3Y镁合金表面制备了复相陶瓷层.通过微观结构分析及电化学测试技术研究了PEO陶瓷层的微观组织及腐蚀行为.结果表明,偏铝酸盐体系中PEO法制备的陶瓷涂层主要由MgO和MgAl2O4相组成,还有少量MgF2相,其中MgAl2 O4尖晶石相约占陶瓷层的19.87％,且由非贯通的等离子体放电微孔与喷射沉积复相氧化物组成.浸泡初期,PEO陶瓷层表现出较好的耐蚀性;浸泡后期,陶瓷层腐蚀电流密度Icorr逐渐增大,陶瓷层电阻Rct快速减小,144 h后陶瓷层的保护能力迅速下降,且陶瓷层表面出现点蚀及裂纹萌生;浸泡过程中,交流阻抗谱由浸泡0～72 h的两个容抗弧转变为浸泡l44～ 300 h的单容抗弧和感抗弧组成,表明腐蚀介质已渗透整个陶瓷层,并萌生点蚀.腐蚀产物主要由Mg(OH)2相组成.陶瓷层的腐蚀主要由等离子体放电微孔开始,逐渐向四周蔓延并形成放射状裂纹而加速腐蚀.
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