| 摘要: |
| 铝合金广泛应用于各个领域，铝合金表面防腐技术前景十分广阔。采用恒流的方式分别在 7075、7A04 和 2A12 三种不同铝合金基体表面进行黑色微弧氧化膜层的制备。通过扫描电子显微镜、X 射线衍射仪、显微硬度测试仪、摩擦磨损试验机和电化学试验研究不同铝合金基体表面黑色微弧氧化膜的微观组织、硬度、耐磨性和耐蚀性。随着膜层厚度的增加，膜层的致密度大幅提高，平均孔隙率降低至 0.8%，膜层中 α-Al2O3的比例增加，耐磨性显著提高，在黑色陶瓷颗粒的自润滑作用下，复合膜层的摩擦因数从 0.6 降至 0.3，摩擦曲线的变化趋势更平稳。黑色膜层厚度从 40 μm 提高到 60 μm，三种铝合金基体的黑色氧化膜层均明显提高，最高达到 916 HV。电化学试验结果 60 μm 黑色微弧氧化膜层的腐蚀电流密度比 40 μm 的降低两个数量级，自腐蚀电位可提高 200 mV，钝化性能增强，膜层耐蚀性显著提升。 |
| 关键词: 铝合金 微弧氧化 耐蚀性 耐磨性 |
| DOI：10.11933/j.issn.1007-9289.20221206001 |
| 分类号:TG178 |
| 基金项目:*“兴辽英才计划”(XLYC1907080)；国家自然科学基金(51974188)；广东省现代表面工程技术重点实验室开放基金(2020B1212060049)资助项目 |
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| Effect of Thickness on Structure and Property of Black Microarc Oxidation Coatings Prepared on Different Aluminum Alloys |
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LIU lei1, LI Laishi1, WU Yusheng1, WANG Yuzheng1, ZHANG Wei2,3, BAO Zebin2, QIAO Ziping4
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1.School of Materials Science and Engineering, Shenyang University of Technology,Shenyang 110020 , China;2.Shi Changxu Center for Innovative Materials, Institute of Metals, Chinese Academy of Sciences, Shenyang 110016 , China;3.Key Laboratory of Modern Surface Engineering Technology, Institute of New Materials,Guangdong Academy of Sciences, Guangzhou 510700 , China;4.Key Laboratory of Transient Impact Technology, 208th Research Institute of China’s Weapons Industry,Beijing 102200 , China
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| Abstract: |
| Aluminum alloys are widely used because of their low density and remarkable strength; however, they are prone to corrosion and wear. Dyeing microarc oxidation technology has gained widespread attention as an emerging surface treatment method. In this study, black microarc oxide coatings are prepared on the surfaces of three aluminum alloy substrates (7075, 7A04, and 2A12) using the constant-current method. The microstructure, hardness, wear resistance, and corrosion resistance of black microarc oxide coatings on the surfaces of the aluminum alloy substrates are investigated using scanning electron microscopy, X-ray diffraction, microhardness testing, friction wear testing, and electrochemical experiments. The black graphite dye improved the microscopic morphology of the film layer and reduced the micropore sizes. Microcracks are significantly reduced, resulting in increased layer thickness without a significant decrease in density. In addition, the change in the aluminum alloy matrix did not alter the structure of the black microarc oxide coatings. The black microarc oxide coatings are mainly composed of α-Al2O3 and γ-Al2O3, with the thickness increasing as γ-Al2O3 gradually transformed into α-Al2O3. The thickness of the microarc oxide coatings are significantly influenced the hardness of the coating layer. For the 7075 aluminum alloy, the average hardness of the black ceramic oxide coating with a thickness of 40 μm is approximately 645 HV, increasing to 731 and 780 HV when the thicknesses of the black microarc oxide coating reached 50 and 60 μm, respectively. The hardness values increased to 790 and 916 HV when the black coating thicknesses reached 50 and 60 μm, respectively. For the 2A12 aluminum alloy, the hardness of the 60-μm-thick black ceramic-oxide coating is significantly higher than those of the 50- and 40-μm-thick coatings, with maximum and minimum hardness values of 904 and 572 HV, respectively, for the 40-μm-thick black ceramic-oxide coating. As the coating thickness increased, the dense density of the coating increased significantly. The average porosity rate decreased to 0.8%, the proportion of α-Al2O3 in the coating increased, and the wear resistance increased significantly. Moreover, the frictional factor of the composite coating decreased from 0.6 to 0.3 with the self-lubrication effect of the black ceramic particles, and the frictional curve tended to change more smoothly. The thickness of the black microarc oxidation coating increased from 40 to 60 μm, and the wear resistance of the black oxide coating on all three aluminum alloy substrates increased significantly. The electrochemical results also show that the corrosion resistance of the three aluminum alloys with black microarc oxide coating thicknesses of 50 and 60 μm is superior. The polarization curves indicates that the corrosion current density of the 60-μm-thick black microarc composite coating is two orders of magnitude lower than that of the 40-μm-thick black microarc oxide coating, and the self-corrosion potential can be increased by 200 mV. The black microarc oxide coatings of the 7A04 and 2A12 aluminum alloys are exhibited improved corrosion resistance, close to the excellent corrosion resistance of the white microarc oxide coating of the 7075 aluminum alloy. The corrosion current density of the 60-μm-thick black microarc oxide coating is two orders of magnitude lower than that of the 40-μm-thick coating, and the self-corrosion potential can be increased by 200 mV. The passivation performance is improved, and the corrosion resistance of the coating is increased significantly. |
| Key words: Al-alloy micro-arc oxidation corrosion resistance abrasion resistance |
