NO₂^-和Cl^-对模拟混凝土孔隙液中钢筋腐蚀行为的影响

来源期刊：金属学报2010年第2期

论文作者：乔冰 杜荣归 陈雯 朱燕峰 林昌健

文章页码：245 - 250

关键词：钢筋； 模拟混凝土孔隙液； Cl^-； 亚硝酸盐

Key words：reinforcing steel； simulated concrete pore solution； Cl^-； nitrite

摘    要：应用极化曲线法和电化学阻抗技术研究了NO₂^-和Cl^-对钢筋在不同pH值的模拟混凝土孔隙液中的腐蚀行为,结果表明,钢筋耐蚀性与溶液的pH值,以及NO₂^-和Cl^-的浓度相关,pH值的降低和Cl^-浓度的增高都会使钢筋的耐蚀性降低。在含Cl^-的模拟液中,随着NO₂^-浓度升高,钢筋腐蚀速率降低,在pH值为12.50和10.50的溶液中,当[NO₂^-]/[Cl^-]≥0.4时,NO₂^-对钢筋具有良好的阻锈作用。

Abstract: Under normal conditions,reinforcing steel in concrete maintains its passivity because of the high alkalinity of the concrete pore solution.However,steel passivity may be broken and the steel corrosion takes place due to concrete carbonation and/or chloride ingress.In fact,premature failure of reinforced concrete structures due to the steel corrosion has been a major problem in civil engineering.Therefore,the study of corrosion and protection of reinforcing steel is of indispensable importance to prolonging the service life of reinforced concrete structures.The application of inhibitors is an effective and economical method to prevent the corrosion of reinforcing steel.NaNO₂ is a notable corrosion inhibitor which is effective in the steel corrosion control by reacting with ferrous ions to form a protective ferric oxide film on the steel surface,but unfortunately it can also accelerate the steel corrosion when the amount of nitrite is insufficient in a medium.In the present work,the linear polarization and electrochemical impedance spectroscopy were used to study the effect of nitrite and chloride ions on the corrosion behavior of reinforcing steel in simulated concrete pore solutions with different pH values.The results showed that the corrosion resistance of reinforcing steel is related with the pH value of the solution,nitrite ion concentrations and chloride ion concentrations.The drop of pH value and the increase of chloride ion concentration would result in the decline of corrosion resistance of reinforcing steel in the solution.The corrosion rate of reinforcing steel decreased with the NO₂^- concentration increasing in the simulated concrete pore solutions with Cl^-,and the NO₂^- ions had a good inhibiting effect on the steel when the concentration ratio of NO₂^- and Cl^- was 0.4 or higher for the solutions of pH=12.50 or pH=10.50.