研究了2A12铝合金微弧氧化陶瓷层的生长动力学, 测定了微弧氧化陶瓷层生长过程中放电参数的变化, 分析了不同氧化时间陶瓷层的表面和截面形貌、成分和相组成。研究表明, 陶瓷层总厚度接近于线性增长, 向外生长速度比向基体内生长的速率稍大。 SEM结果显示, 陶瓷层表面有大量呈火山口状的等离子放电痕迹, 随氧化时间延长, 厚度在整个表面上趋于相等, 界面处氧化膜变得比较平坦。陶瓷层主要由α-Al2O3和γ-Al2O3相组成。随氧化时间延长, γ-Al2O3相在陶瓷层中的含量先增加后减小, 而α-Al2O3相含量随氧化时间的延长逐渐提高。铝合金微弧氧化陶瓷层的生长大致可划分为氧化初期阻挡层的形成、陶瓷层击穿、放电通道扩大、通道内反应形成氧化铝、高压下熔融物喷射-冷却-凝固-相变、形成致密层和疏松层双层结构等六个步骤, 建立了生长模型。

The growth dynamics of micro-arc oxidation (MAO) films on 2A12 aluminum alloy was investigated. The microstructure, morphology, composition and phase constituents under different oxidation time conclitions were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the total film thickness increased linearly and the growth speed towards outer space was faster than that towards substrate. While the ration of dense layer in the film increased firstly then and decreased. The results of SEM show that many crater-mouth like traces formed by the plasma discharge were observed on the coating surface, and the thickness on the cross section became the same and the film/substrate interface became more even with the increase of MAO time. The results of XRD reveal that with increasing the oxidation time the content of γ-Al2O3 in the ceramic coatings inereased first and then decreased, while the content of α-Al2O3 increased. The process can be divided into six steps, including block layer formation, dielectric breakdown of the block layer, broadening of discharge channel, Al2O3 formation through the reaction in the channnel, melted oxide spraying out-cooling-solidification-phase transference, and formation of compact and loose layers.