【摘要】 在青岛工业海洋大气环境中对硫酸及硼硫酸阳极氧化处理的6061铝合金进行5 a的长周期大气暴晒实验,通过表面截面形貌观察、质量损失分析、腐蚀产物分析、力学性能检测和断口分析等方法,研究两种阳极氧化处理对6061铝合金长期腐蚀行为的影响规律及机理。结果表明:经5 a大气暴晒试验后,表面阳极氧化处理能显著降低6061铝合金的平均腐蚀速率及力学性能损失,且硫酸阳极氧化的效果更明显;与裸材相比,硫酸和硼硫酸阳极氧化后5 a暴晒试验的平均腐蚀速率分别下降了70.2%和45.4%,屈服强度损失率分别下降了69.5%和11.0%,伸长率损失率分别下降了71.8%和41.0%。青岛工业海洋大气环境中高浓度的Cl-会对6061铝合金表面的氧化膜侵蚀破坏,穿透氧化膜引起点蚀。当点蚀发生在晶界处时,引发了晶间腐蚀;环境中的硫化物伴随着腐蚀介质可深入到晶界区域,加剧了沿晶裂纹的扩展。阳极氧化膜对Cl-的侵蚀有较强的阻挡作用,且硫酸阳极氧化膜的阻挡作用更好,能有效地抑制晶间腐蚀的萌生和扩展,进而减小了6061铝合金强度及塑性的损失,使得硫酸阳极化6061铝合金具有较好的强度和伸长率。更多还原

【Abstract】 The outdoor exposure tests of anodized 6061 aluminum alloy in sulfuric acid and boron-sulfuric acid were carried in industrial-marine atmospheric environment at Qingdao for five years. The effects of two different anodizing methods on the corrosion behavior and mechanism of 6061 aluminum alloy were investigated by means of the surface and cross-section morphology observation, mass loss method, the corrosion products analysis, mechanical properties testing and fracture analysis. The results show that the average corrosion rates of the anodized alloy in sulfuric acid and boron-sulfuric acid decrease by 70.2% and 45.4% after five-year exposure in the industry-marine atmospheric environments, respectively, compared to the naked alloy. The loss of yield strength decrease by 69.5% and 11.0%, and the loss of elongation decrease by 71.8% and 41.0%. Thus, the anodic treatment weakened corrosion and the effect of sulfuric acid anodizing is much better than for the boron-sulfuric acid anodizing. The high concentration of chloride ions in the industry-marine atmosphere in Qingdao plays an important role in the destruction of the oxide films and in inducing the pitting corrosion. Due to the pitting on the grain boundaries, the intergranular corrosion initiated. The sulfide in the atmosphere can penetrate into the grain boundary region along with the corrosive medium, which aggravate the propagation of the intergranular corrosion. The anodized film has an effective hindrance for chloride ions penetrating to the matrix, and the effect of anodizing in sulfuric acid is better, which can effectively inhibit the initiation and propagation of intergranular corrosion, thereby reduce the loss of strength and plasticity of 6061 aluminum alloys.更多还原