论文部分内容阅读
在含有Na2SiO3、NaAlO2、Na2B4O7、NaOH、C3H8O3和C6H5Na3O7的电解液中,采用交流脉冲电源对AZ91D镁合金进行微弧氧化处理。利用SEM、膜层测厚仪、EDS和XRD分别研究膜层的表面和截面微观形貌、厚度、成分及相结构。利用交流阻抗和动电位极化曲线试验测量膜层在3.5%NaCl中性溶液中的耐蚀性能。结果表明,正交试验得到的双电解液成分为15g/LNa2SiO3、9g/LNaAlO2、2g/LNa2B4O7、3g/LNaOH、5mL/LC3H8O3和7g/LC6H5Na3O7。经过微弧氧化处理而得到的膜层较致密,其腐蚀电流密度较镁合金基体的降低了2个数量级,自腐蚀电位提高了近73mV。EIS结果认为膜层的耐蚀性取决于内部致密层。微弧氧化膜主要组成元素为Mg、Al、O和Si,主要组成相为MgO、Mg2SiO4和MgAl2O4。
In the electrolyte containing Na2SiO3, NaAlO2, Na2B4O7, NaOH, C3H8O3 and C6H5Na3O7, AC pulse power was used to micro-arc oxidation the AZ91D magnesium alloy. The morphology, thickness, composition and phase structure of the surface and cross section of the film were studied by SEM, film thickness gauge, EDS and XRD respectively. Corrosion resistance of the coating in 3.5% NaCl neutral solution was measured by AC impedance and potentiodynamic polarization curves. The results show that the composition of the double electrolyte obtained by orthogonal experiment is 15g / LNa2SiO3, 9g / LNaAlO2, 2g / LNa2B4O7, 3g / LNaOH, 5mL / LC3H8O3 and 7g / LC6H5Na3O7. The micro-arc oxidation treatment results in a denser film. The corrosion current density is reduced by two orders of magnitude compared with the magnesium alloy substrate, and the self-corrosion potential is increased by nearly 73mV. The EIS results suggest that the corrosion resistance of the film depends on the inner dense layer. The main components of MAO films are Mg, Al, O and Si. The main components are MgO, Mg2SiO4 and MgAl2O4.