优化及膜层特性
(1. 江苏科技大学 材料科学与工程学院, 镇江 212003；2. 江苏科技大学 机械工程学院, 镇江 212003)
摘 要: 在硅酸钠、氢氧化钠、四硼酸钠和柠檬酸钠组成的电解液中，采用交流脉冲电源对ZK60镁合金进行微弧氧化，研究电解液组分对膜层的影响规律，并优化电解液配方。利用光学显微镜、扫描电镜(SEM) 、能谱分析(EDS)和X射线衍射分析(XRD)等，研究膜层厚度、表面与截面的微观组织，通过静态腐蚀质量损失法和动电位极化曲线法测试膜层在3.5%NaCl介质中的耐蚀性能。结果表明：各电解液组分浓度对成膜过程的电压变化、膜层厚度和耐蚀性能的影响规律各不相同，并在不同的合适浓度下获得厚的膜层和较高的耐蚀性能。通过单变量实验和正交实验优化电解液配方：60 g/L NaSiO3+20 g/L NaOH+25 g/L NaB4O7+20 g/L C6H5Na3O7，制备出的膜厚高达164.89 μm，结构均匀、致密，腐蚀速率极低，仅为ZK60镁合金空白试样的1.8%。
关键字: ZK60镁合金；微弧氧化；Na2SrO3电解液；配方；膜层
（1. School of Materials Science and Engineering,
Jiangsu University of Science and Technology, Zhenjiang 212003, China;
2. School of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China）
Abstract:The micro-arc oxidation process was conducted on ZK60 Mg alloy in an electrolyte composed of NaSiO3, NaOH, NaB4O7 and C6H5Na3O7 by AC pulse electrical source. The coating thickness and microstructural characteristics of coating cross-section and surface were investigated by means of OM, SEM coupled with EDS and XRD. The mass loss and dynamicpotential curves were measured in a 3.5%NaCl solution to evaluate the coating resistance to corrosion. The results reveal that different elements of the electrolyte demonstrate different effects on process voltage, coating thickness and corrosion resistance. For an element of the electrolyte, there is usually a suitable concentration to obtain a thicker coating but which does not guarantee a better corrosion resistance. By means of single variable and orthogonal tests, an optimized electrolyte with a composition of 60 g/L NaSiO3+20 g/L NaOH+25 g/L NaB4O7+20 g/L C6H5Na3O7 was developed. The sample prepared with the optimized electrolyte exhibits good corrosion property with only 1.8% of corrosion rate of blank sample due to its thicker (164.89 μm) and denser coating.
Key words: ZK60 magnesium alloy; micro-arc oxide; NaSiO3 electrolyte; formula; coating
