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该文针对输水条件下水泥砂浆-球墨铸铁管的腐蚀问题,设计制作了内衬水泥砂浆球墨铸铁管环试件,进行纯净水、6M硝酸铵溶液和6M氯化铵溶液扰动侵蚀下的管环试件线性极化电阻(LPR)和电化学阻抗谱(EIS)测试,分析了不同溶液中试件的线性极化电阻、腐蚀电流密度等电化学参数随腐蚀时间的变化规律,并评估了各试件在不同溶液中的腐蚀程度。结果表明,在120天的腐蚀时间内,纯净水中试件的砂浆层电阻、铸铁表面电荷转移电阻和腐蚀电流密度基本不变;硝酸铵溶液中,试件的砂浆层电阻下降明显,但铸铁表面电荷转移电阻和腐蚀电流密度基本不变;而在氯化铵溶液中,试件砂浆层电阻和铸铁表面电荷转移电阻均降低明显,且腐蚀电流密度远大于铸铁表面脱钝临界值;LPR与EIS所评估的试件腐蚀程度基本一致。
In this paper, for the corrosion of cement mortar-ductile iron pipe under the conditions of water conveyance, a lined cement mortar ductile iron pipe ring test piece was designed and manufactured. The pipe under pure water, 6M ammonium nitrate solution and 6M ammonium chloride solution under perturbation erosion The linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) tests of ring specimens were carried out. The variation law of electrochemical parameters such as linear polarization resistance and corrosion current density in different solutions with respect to corrosion time was analyzed. Corrosion degree of each specimen in different solution. The results show that the resistance of the mortar layer, the surface charge transfer resistance and the corrosion current density of the test piece in pure water are basically unchanged during the 120-day corrosion time. In the ammonium nitrate solution, the resistance of the mortar layer of the test piece decreases obviously, The charge transfer resistance and the corrosion current density are basically unchanged; while in the ammonium chloride solution, the resistance of the mortar layer and the surface charge transfer resistance of the cast iron decrease obviously, and the corrosion current density is much larger than the depassivation threshold of the cast iron surface; LPR and EIS The corrosion of the specimens evaluated is basically the same.