AZ91D镁合金微弧氧化工艺参数的优化

Optimization of Processing Parameters of Micro-arc Oxidation for AZ91D Magnesium Alloy in Silicate Solution

利用自制微弧氧化装置在硅酸盐体系中对AZ91D镁合金进行微弧氧化处理。采用4因素3水平正交试验,从考察膜层厚度、表面粗糙度和耐蚀性出发,确定了AZ91D镁合金在硅酸盐体系中的最佳工艺参数。结果表明:在最佳工艺条件下,微弧氧化膜呈多孔结构、孔径较小,裂纹较少,分布均匀,膜层较为致密;微弧氧化膜由MgO、Mg2SiO4、MgAl2O4和少量的SiO2组成;室温下,在质量分数为3.5%的NaCl中性溶液中浸泡168h后,膜层表面未出现明显的点蚀现象,耐蚀性较镁合金基体有了很大提高。

AZ91D magnesium alloys were processed by micro-arc oxidation(MAO) in silicate solution by means of a self-designed AC(alternative current) power suppler.The optimized processing parameters of MAO for AZ91D magnesium alloy in silicate solution were determined on the basis of an orthogonal testing with four factors and three levels used to systematically investigate the coating thickness,surface roughness and corrosion resistant.The results show that the MAO film is characterized by porous structure and smaller apertures and compact film layer as well as uniform distribution in the surface of the AZ91D magnesium alloy,consisting of MgO,Mg2SiO4,AgAl2O4 and minor SiO2,in the condition of the optimized processing parameters.The absence of apparent pit-erosion in the film surface can be observed after immersing for 168 h in 3.5% NaCl solution at room temperature,demonstrating the corrosion resistance greatly superior to that of AZ91D magnesium alloy substrates.