2A12铝合金在模拟溶液中的周浸腐蚀行为

Corrosion Behaviors of Aluminum Alloy 2A12 under Cyclic Wet-Dry Immersion Test in Simulation Solutions

采用干湿周浸实验、失重法和电化学阻抗谱研究了2A12铝合金在0.6 mol/L NaCl和0.6 mol/LNaCl+0.02 mol/L NaHSO3两种溶液中的腐蚀行为与规律,利用扫描电镜(SEM)、能谱(EDX)和红外光谱(FTIR)观察分析腐蚀产物表面形貌、结构和组成,测试了材料的力学性能。研究表明,随腐蚀时间的延长,腐蚀产物不断增多,失重增加,力学性能下降,阻抗模值逐渐减小;腐蚀产物形貌以团状和块状为主,在0.6mol/L NaCl溶液中腐蚀产物主要为铝的氯化物和氧化铝,在0.6 mol/L NaCl+0.02 mol/L NaHSO3溶液中腐蚀产物主要为氧化铝、铝的硫酸盐水合物和铝的氯化物;由于NaCl和NaHSO3共同作用,2A12合金在0.6mol/L NaCl+0.02 mol/L NaHSO3溶液中腐蚀电流密度高,阻抗模值相对较小,腐蚀速率较高,腐蚀后失重大,力学性能下降幅度较大,腐蚀更严重。

The corrosion behaviors of aluminum alloys 2A12 under cyclic wet-dry immersion conditions in 0.6mol/LNaC1 solution and 0.6 mol/L NaC1 ＋ 0.02 mol/L NaHSO3 solution was investigated by mass loss method and electrochemical impedance spectroscopy （EIS）. Scanning electron microscope （SEM） was used to observe surface morphology. Energy dispersive X-ray detector （EDX） and FTIR were employed to analyze the corrosion products. The results showed that corrosion product is increasing with test hours, corrosion degree growing on, mass loss adding, strength and elongation percentage declining, EIS resistance declining. Surface observation showed that corrosion product is agglomerate and accidented. The corrosion product is composed of alumina and aluminum chloride in 0.6 mol/L NaC1 solution. The corrosion product is composed of alumina, aluminum chloride and sulfate hydrate in 0.6 mol/L NaC1 ＋ 0.02 mol/L NaHSO3 solution. NaC1 and NaHSO3 accelerated material corrosion. Corrosion degree of aluminum alloy 2A12 in 0.6 mol/ L NaC1 ＋ 0.02 mol/L NaHSO3 solution is severer in 0.6 mol/L NaC1 solution, mass loss more, strength and elongation percentage declining more, corrosion reaction resistance smaller, and corrosion current density higher.