6061铝合金自修复MAO膜的制备与腐蚀行为研究

用硅酸盐体系电解液在6061铝合金表面制备自修复微弧氧化膜。用SEM、EDS分析氧化膜表面形貌和元素分布;用X射线衍射仪研究氧化膜的相组成;用盐雾试验研究膜层的腐蚀行为。结果表明:随反应总时间延长,氧化膜厚度逐渐增大,硬度先增后减;XRD和EDS显示氧化膜致密部位和裂纹修复部位的物相组成相同,主要以Al₂O₃和SiO₂为主的莫来石相;盐雾试验和试样腐蚀后的微观形貌表明基体腐蚀最先出现在裂纹处,而非放电孔洞位置。氧化30 min,再在质量分数为5%的NaCl中性盐雾腐蚀306 h,试样表面无明显腐蚀。

Preparation and corrosion behavior of self-repairing micro-arc oxidation film on 6061 aluminum alloy

Self-repair micro-arc oxidation(MAO)coatings were formed on 6061 aluminum alloy in the silicate electrolyte.The surface morphology and element distribution of the MAO ceramic layer were analyzed by SEM and EDS.The phase composition of the MAO ceramic layer was studied by XRD.The corrosion behavior of the coating was investigated by salt spray test.The result show that the thickness of the coatings layer increases with the increase of oxidation time,and the hardness of the coatings increases with the increase of oxidation time and then decreases.XRD and EDS characterization show that the phase of the dense part of the oxide coatings is the same as that of the crack repaired part,it is mainly mullite phase composed of Al₂O₃ and SiO₂.The salt spray test and micro corrosion morphology show that the salt spray corrosion first appears at the crack,but not at the micropore.When the reaction time is 30 min,the sample is resistant to 5% NaCl neutral salt spray for more than 306 hours.