红壤中变电站接地网金属材料的腐蚀行为分析

Corrosion Behavior of Substation Ground Grid in Red Soil

采用扫描电镜(SEM)、能谱(EDS)和X射线衍射(XRD)等技术对红壤中变电站接地网服役长达13 a的镀锌扁钢进行了形貌分析和腐蚀产物分析。结果表明,该镀锌扁钢受到严重腐蚀,腐蚀产物主要由Fe OOH,Fe3O4和Fe2O3等组成,腐蚀产物分层的原因是新生成的腐蚀产物沉积在金属/腐蚀产物层界面或腐蚀产物开裂处,同时S和Cl对内层腐蚀产物具有较大的影响。Tafel测试结果表明,在腐蚀电流峰值附近,SO42-与Cl-的百分比为1∶2时,两者对镀锌Q235碳钢在该红壤中的腐蚀性影响具有等效作用。通过室内加速实验模拟镀锌Q235碳钢在该红壤中的腐蚀发现,镀锌Q235碳钢的腐蚀速率呈现先增大后减小的规律,该加速实验在未改变镀锌Q235碳钢腐蚀机理的同时具有较好的加速效果。

Macroscopic analysis and corrosion product analysis of galvanized flat steel which had been in service for 13 a in substation grounding grid were made by scanning electron microscopy(SEM), energy spectrum(EDS) and X-ray diffraction(XRD). The result shows that galvanized flat steel suffered serious corrosion and corrosion products are mainly composed of Fe OOH, Fe3O4,Fe2O3 and etc. The cause of the corrosion product layer is the new production of corrosion products deposition on the metal/corrosion product layer interface or the cracking. At the same time, S and Cl have great influence on the inner corrosion products. Tafel test results show that the percentage of SO42-and Cl-is 1∶2 and they have equivalent effect on the corrosion influence of galvanized Q235 carbon steel near the corrosion current peak. Result of the accelerated corrosion experiment shows that corrosion rate of galvanized Q235 carbon steel in red soil increase first and then decrease,meanwhile,the corrosion mechanism of galvanized Q235 carbon steel in this acceleration that had a good speedup was unchanged.