带锈碳钢在循环冷却水中的腐蚀行为与对策

发布时间：2018-04-01 16:42

本文选题：A3碳钢　切入点：循环冷却水　出处：《华东理工大学》2017年硕士论文

【摘要】：锈层/金属腐蚀是复杂腐蚀体系之一,锈层下腐蚀是金属腐蚀发展过程中最主要的、持续时间最长的腐蚀形态。因而本文采用的带锈碳钢材料能够更好的模拟碳钢在循环冷却水中的腐蚀发展行为及特征。本课题采用失重法、电化学法(极化曲线、电化学阻抗)、电子显微镜扫描技术(SEM)和红外光谱技术(IR),研究了碳钢在不同循环冷却水中腐蚀速率变化规律;研究了锈层的外貌、结构和组成以及其他因素对带锈碳钢腐蚀的影响;研究了在不清洗预膜的技术处理下,缓蚀药剂对带锈碳钢腐蚀的缓蚀效率。研究结果表明:在循环冷却水的不同条件下,碳钢腐蚀速度随时间的变化趋势一致:浸泡初期,腐蚀介质对碳钢腐蚀影响作用大,此时碳钢的腐蚀速度快且降低幅度大,随着腐蚀时间的延长,腐蚀介质影响作用减弱,腐蚀速率降低趋势减缓,最后趋于平稳,且达到稳定的碳钢腐蚀速率相同。说明锈层对碳钢基体有一定的保护作用,当腐蚀达到一定程度,碳钢腐蚀不再受腐蚀介质的影响。电化学测试表明:锈层对碳钢电极的阴极反应有影响;腐蚀电流密度(Icorr)随腐蚀时间的延长而降低;极化电阻(Rp)随腐蚀时间的延长而增大;Warburg系数(Yo)随腐蚀时间的延长快速降低,远小于溶解氧在锈层中扩散的Yo值,表明锈层能够抑制溶解氧的扩散。随着腐蚀反应的进行,碳钢锈层出现分层,黄色疏松外锈层主要由γ-FeOOH和α-FeOOH组成;黑色致密内锈层由少量的β-FeOOH以及磁性Fe3O4生成。由于β-FeOOH具有较高的电化学活性,使得电化学测定的碳钢腐蚀速率略高于失重法;Fe3O4的缓慢生成,表明其是在缺氧的条件下生成。进一步证明了锈层可阻碍溶解氧向金属基体表面扩散。DJ-NPO1和DJ-304对带锈碳钢均具有很强的缓蚀效果。药剂的缓蚀效率随加药量的增加而提高。综合考虑加药的缓蚀效果、经济性和环保性,确定两种药剂的最佳投加量均为200mg/L,此时两种缓蚀剂的缓蚀效率均可达到70%以上。
[Abstract]:Rust / metal corrosion is one of the complex corrosion systems, and the corrosion under the rust layer is the most important in the development of metal corrosion. Therefore, the corrosion behavior and characteristics of carbon steel in circulating cooling water can be better simulated by using the corroded carbon steel material. In this paper, weightlessness method, electrochemical method (polarization curve, polarization curve, polarization curve) are used to simulate the corrosion behavior and characteristics of carbon steel in circulating cooling water. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and infrared spectroscopy (IR) were used to study the corrosion rate of carbon steel in different circulating cooling water and the appearance of rust layer. The effect of structure, composition and other factors on corrosion of rusty carbon steel was studied. The corrosion inhibition efficiency of corrosion inhibitor on rusty carbon steel without cleaning prefilm was studied. The results showed that under different conditions of circulating cooling water, the corrosion inhibition efficiency of corrosion inhibitor on rusty carbon steel was studied. The corrosion rate of carbon steel varies with time: at the beginning of immersion, the corrosion medium has a great effect on the corrosion of carbon steel, and the corrosion rate of carbon steel decreases greatly, and the effect of corrosion medium weakens with the extension of corrosion time. The decreasing trend of corrosion rate was slowed down, and finally the corrosion rate of carbon steel was stable, and the corrosion rate of carbon steel reached stable, which indicated that rust layer had certain protective effect on carbon steel substrate, and when corrosion reached a certain degree, The corrosion of carbon steel is no longer affected by corrosion medium. The electrochemical test shows that the corrosion current density decreases with the increase of corrosion time, and the corrosion current density decreases with the increase of corrosion time, and the corrosion current density decreases with the increase of corrosion time, and the corrosion current density decreases with the increase of corrosion time. The polarization resistance (RP) increases with the increase of corrosion time and decreases rapidly with the prolongation of corrosion time, which is much smaller than the value of Yo of dissolved oxygen diffusion in rust layer, which indicates that the rust layer can inhibit the diffusion of dissolved oxygen. The rust layer of carbon steel is stratified, the yellow loose outer rust layer is mainly composed of 纬 -FeOOH and 伪 -FeOOH, and the black dense inner rust layer is formed by a small amount of 尾 -FeOOH and magnetic Fe3O4. Because of the high electrochemical activity of 尾 -FeOOH, the black dense inner rust layer is composed of 纬 -FeOOH and 伪 -FeOOH. The corrosion rate of carbon steel measured by electrochemical method is slightly higher than the slow formation of Fe _ 3O _ 4 by weightlessness method. It is further proved that rust layer can hinder the diffusion of dissolved oxygen to the surface of metal matrix. DJ-NPO1 and DJ-304 have strong corrosion inhibition effect on rusty carbon steel. And improve. Consider the corrosion inhibition effect of adding medicine comprehensively, The optimum dosage of the two agents is 200 mg / L, and the corrosion inhibition efficiency of the two inhibitors can reach more than 70%.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

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