生长速率对镁合金微弧氧化膜结构及耐蚀性的影响

Effect of Growth Rate on Microstructure and Corrosion Resistance of Micro-arc Oxidation Coatings on Magnesium Alloy

摘要:

硅酸盐电解液体系中对AZ91D镁合金进行微弧氧化处理,膜层厚度相同但生长速率不同是本研究的实验设计特色。通过调节电源电压,使得膜层的生长速率分别为1μm/min、5μm/min、15μm/min和25μm/min,从而制备出生长速率不同但厚度相同的微弧氧化膜层,对膜层的微观结构及耐蚀性进行定性及定量研究,从实验室研究及实际应用角度对不同生长速率的各膜层进行综合对比分析。结果表明,生长速率对膜层的表面孔隙率、微孔的尺寸及数量,膜层的质量及质量厚度比,以及膜层耐蚀性均有较大的影响,但对膜层中的成分及元素分布基本无影响；在工业应用中,膜层生长速率的选择,应将膜层的生产效率和膜层性能统筹考量,本研究中生长速率为15μm/min的膜层显示出这样的优势。

Abstract:

AZ91D magnesium alloys were processed by micro-arc oxidation (MAO) in silicate-containing electrolyte. The key factor of this research is a unique experimental design to fabricate coatings with same thickness but by different power voltages which represents different growth rate. The fact, that the coatings with same thickness corresponding to different coating growth rate of 1μm/min, 5μm/min, 15μm/min and 25μm/min respectively, makes the comparison and analysis-targeted microstructure and corrosion resistance of the coatings academic and practical. The coating growth rate demonstrates considerable influence on surface porosity, size and amount of micro-pores, mass and mass to thickness ratio, and anti-corrosion property of the coatings based on both qualitative and quantitative analysis, but it is not the case for the composition and element distribution of the coatings. An industrial application-oriented selection of appropriate coating growth rate, which demands for both productive efficiency and good performance, has to be considered together with anti-corrosion property of the coatings. The case of the coating fabricated with the growth rate of 15μm/min supports this point strongly.