论文部分内容阅读
利用盐雾腐蚀与电化学测试方法,研究了氢氧化钠溶液中Na_2S_2O_3浓度对Q235钢材腐蚀行为的影响。利用SEM、EDS观察腐蚀试样的微观形貌与元素分布。采用失重法、晶相法、极化曲线和交流阻抗谱分析了样品的腐蚀速率与点蚀深度。结果表明:在氢氧化钠溶液中,随Na_2S_2O_3浓度的增加,Q235钢材的腐蚀形貌由点蚀逐渐发展为均匀腐蚀,并伴有腐蚀产物的堆积,腐蚀产物主要组成元素为O、S、Fe等。随Na_2S_2O_3浓度的继续增加,腐蚀失重与点蚀深度呈现增加的趋势,分别从3 g/L的2.8867 g/m~2、5.2μm升高到7 g/L的3.1031 g/m~2、7.0μm,腐蚀速率则先急剧增大后增长缓慢。与此同时,随浓度的增加,腐蚀电流密度总体增大,容抗弧半径减小。在碱性溶液中,S_2O_3~(2-)浓度低于3 g/L时,腐蚀较为轻微,S_2O_3~(2-)浓度的提高对腐蚀起明显的促进作用。
Salt spray corrosion and electrochemical test methods were used to study the effect of Na_2S_2O_3 concentration in sodium hydroxide solution on the corrosion behavior of Q235 steel. The microstructure and elemental distribution of the corroded samples were observed by SEM and EDS. The corrosion rate and pitting depth of the samples were analyzed by weight loss method, crystal phase method, polarization curve and AC impedance spectroscopy. The results showed that the corrosion morphology of Q235 steel gradually developed from pitting corrosion to uniform corrosion with the increase of Na 2 S 2 O 3 concentration in sodium hydroxide solution, accompanied by the accumulation of corrosion products. The main components of corrosion products were O, S, Fe Wait. With the concentration of Na_2S_2O_3 increasing, the corrosion loss and pitting depth showed an increasing trend from 2.8867 g / m ~ 2,5.2 μm at 3 g / L to 3.1031 g / m ~ 2 at 7 g / L μm, while the corrosion rate firstly increases sharply and then increases slowly. At the same time, with the increase of concentration, the corrosion current density generally increases and the capacitance arc radius decreases. In alkaline solution, the corrosion is slight when the concentration of S_2O_3 ~ (2-) is lower than 3 g / L, and the increase of S_2O_3 ~ (2-) concentration can promote the corrosion remarkably.