模拟孔溶液中球墨铸铁表面钝化膜脱钝过程及氯离子阈值分析  

Analysis on depassivation process and chloride ion threshold of passive film on surface of ductile iron in simulated pore solution

作　　者：左晓宝[1] 蒋慷 冯禹翔 汤玉娟[1] 孙香花[1] Zuo Xiaobao Jiang Kang Feng Yuxiang Tang Yujuan Sun Xianghua(Department of Civil Engineering, Nanjing University of Science and Technology, Nanjing 2t0094, Chin)

机构地区：[1]南京理工大学土木工程系,南京210094

出　　处：《东南大学学报（自然科学版）》2017年第2期392-396,共5页Journal of Southeast University：Natural Science Edition

基　　金：国家自然科学基金资助项目(51378262);江苏省自然科学基金资助项目(BK20141396)

摘　　要：为了揭示输水过程中内衬水泥砂浆球墨铸铁管的腐蚀机理,开展了球墨铸铁样品在模拟砂浆孔溶液中的腐蚀实验.采用电化学测试方法,研究了模拟孔溶液中球墨铸铁表面钝化膜的脱钝过程,分析了模拟孔溶液碱度和氯离子浓度对球墨铸铁电化学阻抗谱及极化电阻的影响.结果表明:当模拟孔溶液的pH值从13.6降低至11.5时,球墨铸铁表面钝化膜脱钝时的氯离子浓度从0.30 mol/L减小至0,且脱钝时的球墨铸铁阻抗谱和极化电阻发生明显改变;球墨铸铁表面脱钝氯离子阈值与溶液的pH值呈线性关系,且随pH值的降低而减小.所建立的球墨铸铁表面脱钝氯离子阈值方程,为进一步评估内衬水泥砂浆球墨铸铁管的服役寿命提供依据.To reveal the corrosion mechanism of cement-mortar-lined ductile iron pipe in water supply,the corrosion experiments on the ductile iron sample in the simulated pore solution were carried out. By using the electrochemical measurement method,the depassivation process of the passive film on the surface of the ductile iron in the simulated pore solution was studied,and the influences of alkalinity and the chloride ion concentration of the simulated pore solution on the electrochemical impedance spectroscopy（ EIS） and the polarization resistance（ PR） of the ductile iron sample were analyzed. The results showthat,when the pH value of the solution reduces from 13. 6 to 11. 5,the chloride ion concentration in the solution decreases from 0. 30 to 0 mol/L,and the EIS and the PR of the ductile iron sample exhibit obvious changes. The chloride ion threshold of depassivation is linear with the pH value of the solution,and decreases with the decrease of the pH value. The proposed chloride ion threshold equation of depassivation on the surface of ductile iron can provide a basis for further evaluating the in-service lifetime of the cement-mortar-lined ductile iron pipe.

关 键 词：球墨铸铁 模拟孔溶液 钝化膜 脱钝 电化学阻抗谱 氯离子阈值 

分 类 号：TG174.36[金属学及工艺—金属表面处理]