摘要:为了可靠测定和解析锈层下金属腐蚀电化学,分别利用失重法和电化学方法对海水中不同浸泡时间的碳钢电极的腐蚀行为和腐蚀速率规律进行了研究。发现对于长期浸泡的碳钢电极,失重法和电化学方法得到的腐蚀速率结果见存在很大差异。利用XRD测定了长期浸泡后锈层成分的变化,发现长期浸泡碳钢电极锈层中的电化学活性成分β-FeOOH在测试过程中发生还原反应导致利用电化学方法测得的碳钢腐蚀速率大于失重法的结果,并且随浸泡时间的延长,这一偏差也增大。对长期浸泡碳钢电极进行-25μA/cm2阴极恒电流预极化处理后发现,随着浸泡时间的延长极化时间也延长,同时,经过预处理之后的碳钢电极电化学方法测得的腐蚀速率与失重法的结果间具有一致的变化规律,能够减小电化学方法对失重法测试结果的偏差。
Abstrct: As so far, because of the existence of rust complicates the electrochemical corrosion process, it is difficult to accurately measure corrosion rate of carbon steel by traditional electrochemical methods. In this paper, weight-loss method and different electrochemical tests such as polarization curves (PC), electrochemical impedance spectra (EIS) and linear polarization resistance (LPR) were used to study the corrosion behavior of the Q235 carbon steel immersed in seawater for 1 year. The results show that both the electrochemical and weight-loss measurement estimations have the same degressive trends during a short immersion period (for about 8 weeks), while the electrochemical measurement result turns to increase after 8 weeks’ immersion in seawater. The longer the immersion time, the bigger the deviation. The experiment indicated that the rusts deposited on the electrodes had a great influence on the corrosion behavior. The constituents of the corrosion products formed on the rust and base steels were characterized by XRD respectively. There is an obvious increasing of β-FeOOH in the corrosion product accumulated on the carbon steel with the immersing time going, and the reductive reaction of β-FeOOH during the electrochemical test progress leads an overestimate of the corrosion rate, which caused the deviation between weight loss method and electrochemical tests. In order to solve this problem, a -25μA?cm-2 cathodic galvanostatic polarization was done to counteract the reduction current during the electrochemical test progress. After the pre-polarization, the electrochemical measurement results coincided well with weight loss, which means this pre-polarization showed a good calibration of the deviation between the two measurement methods.
大气环境薄液膜腐蚀电化学基础理论研究
彭欣 王佳 王金龙 山川 贾红刚 刘在健 王海杰. 海水中带锈碳钢的腐蚀电化学行为及腐蚀速率测定[J]. 中国腐蚀与防护学报, .
https://www.jcscp.org/CN/Y0/V0/I0/0
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