硼硫酸阳极氧化6061铝合金在不同大气环境中的初期腐蚀行为研究

Initial Corrosion Behavior in Different Atmospheric Environments of 6061 Al Alloy Anodized in Boron-sulfuric Acid Solution

通过在青岛和北京进行6061铝合金户外大气暴露实验,利用形貌观察、失重分析、力学性能分析和断面分析等方法,研究了经硼硫酸阳极氧化处理的6061铝合金在工业-海洋大气环境和北方半乡村大气环境中的初期腐蚀规律和机理。结果表明,表面阳极氧化的试样与裸材相比,在工业-海洋大气环境和北方半乡村大气环境一年暴露试验的平均腐蚀速率分别下降43.4%和10.1%,即阳极氧化处理降低材料腐蚀速率,且在恶劣腐蚀环境下的效果更明显;但相对于裸材在工业-海洋大气环境一年暴露试验后的延伸率比初始值下降35%,阳极氧化试样的延伸率下降幅度仍达23%,即硼硫酸阳极氧化对工业-海洋大气环境下合金的力学性能保护不够,塑性降低幅度大,对应的断裂机理发生改变,点蚀导致合金表层从韧性断裂转变为解理脆性断裂。

The initial corrosion behavior and mechanism of 6061 aluminum alloy anodized in a solution of mixed boron-sulfuric acidswere studiedthrough outdoor exposure tests in industry-marine and northernsemi-ruralatmospheric environments at Qingdao and Beijing respectively by means of weightloss measurement, mechanical property testand morphology observation of surface andfracture surface. The results show that after exposed in the industry-marine and the northernsemi-ruralatmospheric environment for one year, the average corrosion rates of the anodized alloy decrease 43.3% and 10.1%, respectively in comparison to the naked alloy, thus the anodic treatment impedes the corrosion and this effect is much efficient in the severer environment. The break elongation of the naked alloy exposed in industry-marine environment for one year decreases 35% in comparison with the original one, but the decrease for the anodized alloy is 23%. Therefore, the anodization with boron-sulfuric acid is not enough to prevent the plasticity deterioration of the alloy; correspondingly, ductile fracture of the surface layer has changed to brittle cleavage. Nevertheless, the above results provide an important reference to the corrosion and protection of aviation materials.