AZ31镁合金双稀土转化膜的TiO_2溶胶处理

TiO_2 Sol Treatment of Double Rare-earth Conversion Film on AZ31 Mg Alloy

采用TiO_2溶胶对双稀土转化膜进行处理,膜的表面形成了新的膜层。SEM表明经TiO_2溶胶处理后双稀土转化膜表面有新物质覆盖在裂纹中,使裂纹减小,未露出内层膜,膜层变得均匀完整。极化曲线和交流阻抗对TiO_2处理后的双稀土转化膜进行电化学测试,表明采用TiO_2处理后试样的腐蚀电位由-1.143 V升高到-0.747 V,腐蚀电流密度降低了两个数量级,并且交流阻抗谱的容抗弧半径增大,极化电阻由1.61 kΩ增大到1.81 kΩ,试样的耐腐蚀性得到了明显的提高。

New film was formed on the surface of double rare-earth conversion film, treated by TiO2 sol. The double rare-earth conversion films treated by TiO2 sol were tested by SEM, potentiodynamic polarization and electrochemical impedance spectroscopy （EIS）. The SEM showed that some new substance appeared in the cracks at the surface of the double rare-earth conversion films. The inside film wae unexposed and the cracks decreased, then the films became more uniform. The corrosion potential of the specimen was improved from -1. 167 V to -0. 777 V. the corrosion current density was reduced by two orders of magnitude The radius of capacitance loops of EIS was enlarged, and the polarization resistance was improved from 1.62 kΩ to 1.81 kΩ. The corrosion resistance of the specimen increased obviously.