【作者】 李海洪；

【导师】 郭兴蓬； 赵永韬；

【作者基本信息】 华中科技大学 ， 应用化学， 2006， 硕士

【摘要】 电化学方法测量快速简便,可以获得丰富的界面过程信息,是缓蚀剂研究的基本方法。酸性介质中,缓蚀剂在电极上吸附的动态过程要求快速提供界面状态变化的信息,同时不影响其吸附状态。恒电量测量方法具有快速微扰的特点,能同时获得多个电化学参数,适合酸性介质缓蚀剂性能和机理的研究。本文讨论了动电位极化曲线、电化学阻抗谱和恒电量测量方法在酸性介质缓蚀剂研究中的优势和不足,在此基础上,研究了硫脲、十二胺和丙炔醇等三种常见酸性介质缓蚀剂对Q235钢在酸性溶液中的缓蚀行为和机理,并深入探讨了缓蚀剂的阳极脱附和浓度极值现象。主要的研究结果有:稳态极化曲线方法能够判断缓蚀剂的类型,并且可以从阴极Tafel直线外推计算腐蚀电流,但其强极化会导致缓蚀剂阳极脱附。电化学阻抗谱可获得缓蚀剂吸附过程的丰富信息,但无法得出腐蚀速率,而且测试时间较长,不利于快速测量。恒电量法测得的极化电阻等于电荷传递电阻,并能快速测得Tafel斜率,直接计算腐蚀速度,从而快速、准确地评价酸性介质缓蚀剂。Q235钢在酸性介质缓蚀剂中的电化学结果表明,十二胺以覆盖效应为主,硫脲则主要抑制Q235钢的阴极过程,而丙炔醇属于以抑制阳极反应为主的缓蚀剂。采用电化学方法研究了不同浓度丙炔醇的缓蚀行为,结果表明,丙炔醇的缓蚀效率在4 h时出现明显的浓度极值,24 h后浓度极值现象不明显,原因是随着时间的延长,丙炔醇的吸附致密性增加。更多还原

【Abstract】 Electrochemical methods, which can conveniently and rapidly provide abundant interface information of inhibition system, are useful tools for corrosion inhibitors research. In acid solutions, the dynamic process of inhibitors adsorbing on electrode demands rapid measurements to provide information of interface changes as well as not to disturb the adsorption state. The coulostatic method having advantages of rapid measurement and weak perturbation enables determination of instantaneous parameters for interface reaction, so it is suitable for investigating corrosion inhibitor behavior and mechanism in acidic mediums.In this thesis, the advantages and disadvantages of potentiodynamic polarization curve, electrochemical impedance spectroscope (EIS) and coulostatic method for studying corrosion inhibitors in acidic mediums were compared. And then the effect of three popular acid corrosion inhibitors such as thiourea, dodecylamine and propargyl alcohol on the corrosion inhibition behaviors of Q235 steel in acidic solutions were investigated by these techniques. The anodic desorption behavior and extreme value phenomenon of concentration were surveyed thoroughly as well. The main conclusions as follows:Potentiodynamic polarization curve can classify inhibition mechanisms and deduce corrosion current from cathodic Tafel lines extrapolation. However, its intensive polarization causes anodic desorption of inhibitors. Although EIS can provide abundant information of adsorption process, the corrosion velocity can not be obtained directly. Moreover, the experiment duration is too long to measure rapidly. In coulostatic measurements, polarization resistance is always close to charge transfer resistance and Tafel slopes can be obtained instantaneously. Therefore, this method can obtain more accurate instantaneous corrosion rate and facilitate the rapid procedure for the evaluation of corrosion inhibitors simultaneously.The electrochemical results of Q235 steel clearly showed that, dodecylamine restrain corrosion mainly by geometric blocking effect; Thiourea decreased the cathodic current effectively and propargyl alcohol suppressed the anodic reaction instead.Inhibition behaviors of PA at different concentrations were investigated as well. The results showed that there existed an extreme value phenomenon of concentration after immersion 4 hours. However, this phenomenon was not significant after immersion 24 hours, which indicated some changes of the adsorption layer of the inhibitor. This may be attributable to the adsorption density of PA molecules increasing with time.更多还原