硫脲基咪唑啉季铵盐缓蚀剂对X80管线钢腐蚀的影响

Effect of Thiourea Imidazoline Quaternary Ammonium Salt Corrosion Inhibitor on Corrosion of X80 Pipeline Steel

考察硫脲基咪唑啉季铵盐(IM-S1)缓蚀剂对X80管线钢在3种不同pH的模拟油田水溶液中的缓蚀性能。采用电化学极化曲线、电化学阻抗分析、SVET、表面形貌分析等方法,研究缓蚀剂在不同pH、不同温度的模拟油田水溶液对X80管线钢的缓蚀性能。极化曲线测试显示,pH7.2环境中的腐蚀电流密度最小,其次是pH10.5,在p H3.5环境中的腐蚀电流密度最大;并随温度升高,腐蚀电流密度均有所升高。电化学阻抗的测试表明,在pH7.2模拟溶液条件下,所显示的容抗弧直径最大,且拟合结果中Rct明显高于其他两种测试条件。SVET分析显示,在pH7.2的测试条件下,管线钢表面吸附成膜性要优于其他两种测试条件;且离子电流密度随时间呈下降趋势,说明缓蚀剂粒子更适宜在此p H值条件下吸附成膜。根据SEM分析,可以明显看出,IM-S1缓蚀剂在中性条件的缓蚀效果要优于p H3.5和p H10.5条件的缓蚀作用效果。IM-S1缓蚀剂更适宜在中性条件下使用,并且在中低温(40~60℃)条件下具有良好的缓蚀效果。该类缓蚀剂在中性溶液条件的吸附成膜性要优于酸性和碱性条件的成膜性,并且吸附成膜降低离子电流密度,从而有效降低腐蚀反应速率。

The effect of the thiourea base imidazoline quaternary ammonium salt corrosion inhibitor on the corrosion performance of X80 pipeline steel in three simulated oil-field waters with different pH was assessed by means of polarization curve measurement,electrochemical impedance spectroscopy(EIS)and scanning vibrating electrode technique(SVET)as well as characterization of corrosion morphology and corrosion products.Polarization curve measurement showed that the corrosion current density was the lowest in the water of pH7.2,followed by p H10.5,while the corrosion current density was the highest in the water of pH3.5,and as the temperature increased,the corrosion current density also increased.The EIS results showed that the diameter of capacitive reactance arc was the largest in the water of p H7.2,accordingly,the Rctin the fitting result was significantly higher than those in the other two waters.The SVET analysis revealed that the adsorption film formation on the surface of pipeline steel in the water of p H7.2 was better than in the other two waters,while the ion current density decreased with time,indicating that the corrosion inhibitor molecule is more suitable for the case in the water of pH7.2.The film formation by adsorption reduces the ion current density,thereby effectively reduces the corrosion reaction rate.In conclusion,the corrosion inhibitor is much suitable for use in neutral waters and it has good corrosion inhibition effect in the temperature range of 40~60℃.