中文摘要：

采用模拟大气腐蚀系统,利用OM,SEM,XRD和局部交流阻抗测试（LEIS）等研究了20碳钢在高湿度SO2大气环境中腐蚀产物的形态变化和生长过程.结果表明,20碳钢表面首先生成Fe（OH）2膜,Fe（OH）2膜在酸性介质中发生破裂形成头部为绿色的丝状物,丝状物沿晶界腐蚀并向铁素体内生长;空气中SO2,O2和H2O不断进入破裂的Fe（OH）2膜内,导致Fe不断溶解并形成FeSO4巢穴,FeSO4与O2和H2O作用在巢穴内生成FeOOH堆积物,最后形成胞状腐蚀产物.随腐蚀时间的延长,胞状腐蚀产物增多,锈层阻抗增加,腐蚀产物层厚度不均匀;继续腐蚀,腐蚀产物变得均匀致密SO2含量越高,胞状物增加越快.

英文摘要：

The evolution of corrosion products of 20 carbon steel in simulated humidity atmosphere containing SO2 was investigated by means of OM,SEM,XRD and localized electrochemical impedance spectrum（LEIS）.Results showed ferrous hydroxide film firstly formed on the sample surface; the film ruptured in the acidic medium,and then filaments with green heads occurred.The filaments grew along the grain boundaries and into ferrite grain.Ferrite phase was dissolved when SO2,O2 and H2O continuously penetrated into the ruptured ferrous hydroxide film and sulphate nests formed.Inside the nests FeSO4 reacted with O2 and H2O to form FeOOH,finally the cellular corrosion products formed.The cellular corrosion products and its impedance increased,and the rust layer became even and compact with further corrosion.Cellular products grew faster with the increasing SO2 concentration.