关键词: 钠基膨润土, 降阻剂, 无机复配缓蚀剂, Q235钢, 电化学, 腐蚀, 缓蚀协同效应

Abstract: 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.

Key words: sodium bentonite, ground resistance reducing material, inorganic complex inhibitor, steel Q235, electrochemistry, corrosion, synergistic inhibitive effect