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利用动电位扫描(PDS),电化学阻抗谱(EIS)和线性极化电阻法(LPR),研究了石英砂沉积物覆盖下的X65管线钢在含氧盐溶液中的腐蚀行为及有机膦缓蚀剂乙二胺四亚甲基膦酸钠(EDTMPS)的作用效果.通过丝束电极(WBE)对沉积物所导致的电偶效应进行了测试.结果表明,沉积物覆盖下的X65钢平均腐蚀速率变缓,但伴随有局部腐蚀发生.在溶液中加注35 mg/L的EDTMPS后,裸露的X65钢电极的腐蚀速率在3 h内由0.17 mm/a降低并稳定在0.082 mm/a,沉积物覆盖下的X65钢电极在6 h内腐蚀速率由0.051 mm/a降低到0.026 mm/a并保持稳定,EDTMPS对裸钢和沉积物覆盖下的碳钢均有良好的缓蚀效果.WBE电偶效应测试结果表明,沉积物覆盖区域电位较低,表现为阳极区并伴随有严重的局部腐蚀发生.在注入35 mg/L缓蚀剂后,WBE平均电位迅速下降,阳极区域逐渐减小,在加入EDTMPS缓蚀剂24 h后,最大阳极电流密度和阳极总电流分别从0.21 m A/cm2和0.056 m A降低至0.078 m A/cm2和0.021 m A.监测数据表明,EDTMPS对沉积物覆盖所引起的电偶效应也有一定的抑制作用.
The corrosion behavior of X65 pipeline steel under the deposition of quartz sand in oxygenated salt solution and the effect of organic phosphine buffer were studied by using potentiodynamic scanning (PDS), electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) Ethane ethylenediamine tetramethylene phosphonate (EDTMPS). The galvanic effect caused by sediment was tested by the wire electrode (WBE) .The results showed that the average coverage of the X65 steel The corrosion rate slowed down but accompanied by the local corrosion.The corrosion rate of exposed X65 steel electrode decreased from 0.17 mm / a to 0.82 mm / a within 3 h after adding 35 mg / L EDTMPS The corrosion rate of X65 steel electrode covered by sediment decreased from 0.051 mm / a to 0.026 mm / a in 6 h and remained stable. EDTMPS had good corrosion inhibition effect on both bare steel and carbon steel covered by sediment. The results of WBE galvanic effect show that the potential of the area covered by the sediment is low and the anodic zone is accompanied by severe localized corrosion.When 35 mg / L inhibitor is added, the average potential of WBE decreases rapidly and the anode area decreases gradually Small, after adding EDTMPS inhibitor 24 h, the maximum anode current density and total anode current From 0.21 m A / cm 2 and 0.056 m A to 0.078 m A / cm 2 and 0.021 m A. The monitoring data show that EDTMPS also inhibits the galvanic effect caused by the deposition of sediments.