含SO_2大气中湿度对低碳钢腐蚀行为的影响

摘要

Through simulated polluted atmospheric corrosion system,the effect of relative humidity（RH） on the corrosion morphology and the growth process of corrosion products of 20 low carbon steel in atmosphere containing 5×10-6 volume fraction SO2 was studied by means of optical microscopy,SEM,XRD and XPS.The results show that the corrosion products were mainly composed of α-FeOOH,γ-FeOOH,FeSO4,Fe3O4,γ-Fe2O3 under the enviroment of different relative humidities,and the concentration of FeOOH increased with increase of RH,and the corrosion rate increased,too.When the RH were 65% and 75%,the corrosion curves was divided into two stages which respectively followed by exponential increase and the linear growth.When the RH were 85% and 95%,the corrosion curves followed by linear growth.At the enviroment of RH of 65%,the corrosion products grew in the form of corrosion-ring.With increase of RH,the filiform corrosion products were found around the corrosion-ring.When the RH was 95%,it was filiform corrosion products with cellular corrosion products,and obvious pits were observed under the cellular corrosion products.%采用模拟污染大气腐蚀系统,利用光学显微镜、SEM、XRD和XPS等研究了湿度对含体积分数为5×10-6的SO2环境中20低碳钢腐蚀形貌和腐蚀产物生长过程的影响。结果表明：在不同湿度环境中,腐蚀产物均主要由α-FeOOH、γ-FeOOH、FeSO4、Fe3O4、γ-Fe2O3组成;随湿度增大,FeOOH含量增多,低碳钢的腐蚀速率增大;在相对湿度为65%,75%时,腐蚀曲线分为指数增加和线性增加2个阶段,在85%,95%时,腐蚀曲线符合线性增长规律;在相对湿度为65%的环境中,腐蚀产物主要以腐蚀圈形式生长,随着相对湿度增加,腐蚀圈周围有短小丝状腐蚀产物出现;在相对湿度为95%时主要为丝状腐蚀产物,其上伴随有胞状腐蚀产物生成,且在胞状腐蚀产物下存在明显的腐蚀坑。