摘要
以硅酸盐溶液为电解液,测量了5083铝合金微弧氧化膜的生长曲线。分析了氧化膜的结构、成分和相组成,并通过盐雾腐蚀试验、动电位极化曲线和电化学阻抗谱(EIS)测量,评估了微弧氧化表面处理前后试样的腐蚀特性。微弧氧化初期,电流密度快速下降,膜层主要是向外生长,膜层粗糙度快速增加。氧化30min后电流密度逐渐降低,膜层逐渐变为向内生长为主。5083铝合金微弧氧化膜由γ-Al2O3和少量莫来石相(3Al2O3·2SiO2)组成,莫来石主要分布在膜外层中。微弧氧化表面处理的5083铝合金腐蚀电流密度减小2个数量级,电化学阻抗模值|Z|增加,耐腐蚀性能得到了显著的改善。此外,由EIS图谱证实,内层膜致密性对微弧氧化膜耐蚀性起决定作用。
A ceramic coating on 5083 aluminum alloy was prepared by micro-arc oxidation （MAO） in silicate solution, and the growth curve of the coating was drawn. The morphology, composition and phase constituent of the MAO coating were analyzed. The corrosion properties of 5083 aluminum alloy sample before and after the MAO surface treatment were evaluated by salt spray corrosion test,potentiodynamic polarization curves and electrochemical impedance spectroscopy （EIS）. In the initial stage, the current density is dropped rapidly and the coating is grown mainly towards the outer surface, and the surface roughness of the coating is increased rapidly. More than 30 min, the current density is decreased slowly and the coating is grown gradually towards the inner layer of coating. The MAO coating on 5083 aluminum alloy consists of y-AlzO3 and a small amount of mullite （3A2O3· 2SIO2） phases, and the mullite mainly appears in the outer layer of coating. Moreover, by microarc oxidation surface treatment, the corrosion current density of 5083 aluminum alloy is decreased by about two order degree of magnitude, and its electrochemical impedance modulus ｜Z｜ is obviously increased, improving significantly the corrosion resistance of coated 5083 alloy. In addition, the fitting analysis of EIS shows that the corrosion resistance of the MAO coating is controlled by the compactness of inner layer.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2013年第1期85-89,共5页
Special Casting & Nonferrous Alloys
基金
国家自然科学基金资助项目(51071031)
北京市自然科学基金资助项目(2102018
2122017)
中央高校基本科研业务费专项资金资助项目
关键词
微弧氧化
5083铝合金
生长曲线
腐蚀
电化学阻抗谱
Microarc Oxidation
5083 Aluminum Alloy
Growth Curve
Corrosion
Electrochemical lmpedance Spectroscopy
