新型无机复配缓蚀剂对钠基膨润土中Q235钢的缓蚀作用

Anti-corrosion effect of new type inorganic complex inhibitor on Q235 steel in sodium bentonite

钠基膨润土是电网工程上常用的降阻剂,可以保证接地网良好的接地导通性,向其中加入缓蚀剂是降低接地网材料腐蚀的有效方法。本文采用动电位极化和电化学阻抗谱(EIS)研究了新型复配缓蚀剂(Na2B4O7、Na2MoO4、NaNO2)和各单组分缓蚀剂在0.75%、1.50%和3.00%质量分数下对接地网常用的Q235钢在钠基膨润土降阻剂中的缓蚀行为。用埋片失重法、SEM、XPS分析了腐蚀速率、腐蚀形貌和腐蚀产物。结果显示Q235钢在钠基膨润土降阻剂中会产生较严重的腐蚀,主要腐蚀产物为Fe2O3以及少量FeOOH。Q235钢在高含水钠基膨润土中的腐蚀受电荷转移控制,复配缓蚀剂可大幅提高电荷转移电阻和电化学阻抗。该无机复配缓蚀剂在保证降阻剂体系较低电阻率的同时具有优良缓蚀效果。在1.5%和3.0%质量分数下,短时和较长期埋放缓蚀效率均可达99%以上。在相同浓度情况对比下,复配缓蚀剂体系中Q235钢的年腐蚀速率比单组分缓蚀剂体系中更低,并且复配体系的电化学阻抗和电荷转移电阻更高,有着明显的协同效应,具有工程推广价值。

In order to maintain the high conductivity of grounding grids,one of the conventional methods is to apply resistance reducing materials such as sodium bentonite.In this method,the corrosion inhibitors are necessary to protect steels.The inhibitive effects of single-component Na2B4O7,Na2MoO4,NaNO2 and the complex inhibitors made of them by varying the mass fraction(0.75%,1.50%and 3.00%)on the Q235 steel in sodium bentonite were investigated using dynamic potential polarization and electrochemical impedance spectroscopy(EIS).The buried test,XPS and SEM with EDS were used to observe the appearance of the corroded regions and analyze the corrosion products.The results indicated that Q235 steels buried in sodium bentonite was seriously corroded,and the corrosion products were Fe2O3 and a small amount of FeOOH.The corrosion rate of the Q235 steel buried in sodium bentonite with high water content is controlled by the charge transfer,and the complex inhibitors can enhance the charge transfer resistance and the electrochemical impedance considerably.The corrosion processes of Q235 were prohibited effectively when the complex inhibitors were added.In the condition that the mass fraction were 1.50%and 3.00%respectively for a short and long period,the inhibition rates on Q235 both exceeded 99%,meanwhile the resistances of system were still low.Compared with single-component inhibitors under the same concentrations,the complex inhibitors showed obvious synergistic inhibitive effect,giving lower corrosion rate and higher charge transfer resistance.