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通过室内模拟实验,研究了含体积分数4×10-6SO2大气中AZ91D镁合金的腐蚀行为。利用原子力显微镜、金相显微镜和扫描电镜观察腐蚀形貌,用XRD分析腐蚀产物。AZ91D镁合金腐蚀1200h的增重变化分为2个阶段,第1阶段符合线性增加规律,第2阶段符合指数衰减规律。腐蚀过程中,β相作为阴极,α相作为阳极,在其上形成颗粒状腐蚀产物,产物不断增多蔓延,直至完全覆盖镁合金表面。同时,在这层产物的裂纹处出现大颗粒产物。腐蚀产物主要为MgO,Mg(OH)2,MgSO3·6H2O,MgSO4·6H2O,随着腐蚀时间的延长,MgO与Mg(OH)2的量减少,而MgSO3·6H2O和MgSO4·6H2O的量增加。
Through laboratory simulation experiments, the corrosion behavior of AZ91D magnesium alloy in the atmosphere containing 4 × 10-6SO2 volume fraction was studied. The corrosion morphology was observed by atomic force microscope, optical microscope and scanning electron microscope. The corrosion products were analyzed by XRD. The weight gain change of AZ91D magnesium alloy after 1200h corrosion is divided into two stages, the first stage accords with the law of linear increase and the second stage accords with exponential decay law. Corrosion process, β phase as the cathode, α phase as the anode, the formation of particulate corrosion products, the product continues to increase until the full coverage of the magnesium alloy surface. At the same time, a large particle product appears at the crack of this layer of product. The corrosion products are mainly MgO, Mg (OH) 2, MgSO36H2O and MgSO4.6H2O. With the increase of corrosion time, the amount of MgO and Mg (OH) 2 decreases and the amount of MgSO36H2O and MgSO4.6H2O increases.