氧化时间对AZ31B镁合金微弧氧化涂层结构及性能的影响

Effect of Oxidation Time on Structure and Properties of Micro-arc Oxidation Coating on AZ31B Magnesium Alloy

目的探索氧化时间对AZ31B镁合金表面微弧氧化(MAO)涂层结构及性能的影响规律。方法通过恒压MAO的方法在硅酸盐电解液体系中制备涂层,采用扫描电子显微镜(SEM)、Image-J图像分析法、测厚仪、表面粗糙度仪、摩擦磨损试验机、盐雾试验箱来研究涂层表面微观形貌、表面孔隙率、厚度、粗糙度、摩擦性能以及耐蚀性能。结果涂层孔隙率随着氧化时间的延长而减小,氧化25min所得涂层孔隙率最小,为5.404%。涂层厚度随时间的延长而增大,但是厚度增长速率减小,氧化5min时涂层厚度为9μm,而25min时涂层厚度为10.4μm。涂层粗糙度与摩擦系数随时间的增加而增大,磨损率随氧化时间的增加,呈现先增大后减小的趋势,氧化15min所得样品磨损率最高,氧化5min所得涂层耐蚀性最差,氧化25min的涂层耐蚀性最好。结论恒压条件下,氧化时间的延长可以有效地减小涂层表面孔隙率,增加涂层厚度,显著改善涂层的耐磨、耐蚀性能。

The work aims to explore the effect of oxidation time on the structure and properties of micro-arc oxidation (MAO) coating on AZ31B magnesium alloy.The coatings were prepared in the silicate electrolyte system by constant pressure MAO method.The micro-morphology,surface porosity,thickness,roughness,friction properties and corrosion resistance of the coatings were studied by scanning electron microscopy (SEM),Image-J analysis method,thickness gauge,surface roughness tester,material surface performance comprehensive tester and salt spray test.With the prolongation of oxidation time,the porosity of the coatings decreased and reached to the minimum value of 5.404% after 25 min of oxidation.The thickness of the coatings increased with the prolongation of oxidation time,but the growth rate of the thickness decreased.The thickness of the coatings was 9 μm after 5 min oxidation and 10.4 μm after 25 min oxidation.The roughness and friction coefficient of the coating increased as the time increased.With the increase of oxidation time,the wear rate firstly increased and then decreased.The wear rate of samples obtained after 15 minutes of oxidation was the highest;the corrosion resistance of coatings obtained after oxidation for 5 minutes was the worst,and that of coatings obtained after 25 minutes of oxidation was the best.Under constant pressure, the prolongation of oxidation time can effectively reduce the surface porosity of the coating,increase the thickness of the coating,and significantly improve the wear resistance and corrosion resistance of the coating.