材料期刊网

采用微弧氧化技术在7075铝合金表面制备保护性涂层, 考察工艺参数对涂层生长过程的影响规律, 利用SEM和XRD测试微弧氧化涂层的微观组织, 通过中性盐雾实验评价涂层的耐腐蚀性能, 通过摩擦磨损实验研究涂层的摩擦磨损特性. 结果表明, 电流密度和氧化时间是影响微弧氧化涂层质量和厚度的重要参数; γ-Al₂O₃是微弧氧化涂层的主要组成相, 基体材料成分和电解液组分都会影响涂层的相组成; 涂层厚度以及封孔处理对涂层的耐腐蚀性能具有显著影响, 经适当工艺制备和处理的微弧氧化涂层耐中性盐雾实验时间可达2000 h以上, 耐蚀性优异; 微弧氧化处理能够显著提高7075铝合金的耐磨性, 与7075铝合金基体和硬质阳极氧化膜相比, 微弧氧化涂层的耐磨性分别提高了约400倍和50倍.

Microarc oxidation (MAO), an important surface treatment technology for Al alloys in stead of hard anodization, was applied to prepare coating on Al alloy 7075, of which the microstructure and properties of the anti-corrosion and anti--wear were studied by XRD, SEM, neutral salt spray (NSS) test and ball-on-disc friction and wear test. The results show that the MAO coating formed on Al alloy 7075 mainly consists of γ-Al₂O₃, α-Al₂O₃ and some amorphous SiO₂. Si element results from electrolyte or from substrate. MAO coating exhibits excellent corrosion resistance, for example, coatings with thickness of 70 μm can endure more than 2000 h in NSS test even without seal treatment. Dense microstructure of MAO coating results in the excellent corrosion resistance. Post seal treatment can greatly enhance the corrosion resistance of the MAO coating, even for thin coating. MAO coating fabricated on Al alloy 7075 possesses similar friction coefficient but much higher wear resistance compared with hard anodized film, for example, the former is as 50 times as the wear resistance of the later. The MAO coating is just slightly worn and its frication coefficient remains unchanged throughout the test.