交流杂散电流对Q235钢在酸性模拟土壤溶液中腐蚀的研究

发布时间：2018-06-06 14:22

本文选题：交流杂散电流 + Q235钢　；参考：《西安理工大学》2017年硕士论文

【摘要】：随着埋地管道、电气化铁路和高压交流输电线越来越多,使流入地下的杂散电流量越来越多,而酸性土壤的腐蚀性较强、交流电方向的可变性和交变频率的不一致性,使得人们对交流杂散电流腐蚀问题的规律没有完全认识,至今没有建立合理的交流杂散电流机理模型,使杂散电流腐蚀的预测,评价和防护比较困难。根据以上问题,本文以Q235钢在酸性模拟土壤溶液中的腐蚀为研究对象,采用电化学测试,失重法,形貌分析,循环伏安曲线分析法研究了交流杂散电流对Q235钢在酸性模拟土壤溶液中的影响规律。研究结果表明:(1)交流杂散电流加速Q235钢在酸性土壤中的腐蚀。在模拟酸性土壤溶液中,外加电压不变的情况下,交流频率使Q235钢腐蚀呈指数变化规律。在电压一定的情况下,交流电频率越高,交流杂散电流对腐蚀的加速作用越小,频率越低,加速作用越大;(2)频率不变的情况下,腐蚀速率随交流电压的增加而增加。施加的交流电压越大,Q235钢的腐蚀越严重,外加交流电位与腐蚀速率成v=0.045+0.273φ的线性关系;(3)交流杂散电流电压会引起Q235钢腐蚀电位的偏移,正扫过程和反扫过程的电位偏移方向相反。当交流杂散电流电压增大,电位正扫时,Q235钢试样的腐蚀电位发生负向偏移;电位反扫时,Q235钢试样的腐蚀电位发生正向偏移;(4)一个交流循环作用下的Q235钢电极表面的反应分为三个阶段:Ⅰ:阳极的活性溶解阶段Ⅱ:析氢极化阶段Ⅲ:析氢控制阶段。由于析氢反应阶段的存在,在相同的条件下,虽然交流杂散电流造成材料的损失量比直流杂散电流要小,但是析氢反应产生的氢气会使材料容易发生氢脆现象,因此腐蚀更严重;(5)在频率较低时,在电流为零附近出现了一个强极化的平台,电极过程以电化学极化为主,当频率较高时,这种平台消失电极电位以外电压为主要因素,电化学极化被忽略,电流由大向小进行时,平台出现的较早,在电流由小向大时,平台出现的也较早,即在一个循环过程中,出现的两个平台不相重合。外电位越大,这两个平台相差越大,出现平台的频率小于1Hz。
[Abstract]:With the increasing number of buried pipelines, electrified railway and high pressure AC transmission lines, more and more stray electric flux inflow into the underground, and the corrosiveness of acid soil is stronger, the variability of alternating current direction and the inconsistency of alternating frequency make people do not fully understand the law of AC and stray current corrosion problem, and have not been built up to now. A reasonable AC stray current mechanism model makes it difficult to predict, evaluate and protect the corrosion of stray current. According to the above problems, the corrosion of Q235 steel in acid simulated soil solution is studied by electrochemical test, weight loss method, morphology analysis, and cyclic voltammetry curve analysis method to study the AC stray current to Q235 The effect of steel in acid simulated soil solution shows that: (1) AC stray current accelerates the corrosion of Q235 steel in acid soil. Under the condition of constant voltage in the simulated acid soil solution, the AC frequency makes the corrosion of Q235 steel exponentially changing. The higher the AC frequency, the higher the AC frequency is, the higher the AC frequency, the AC frequency is higher. The smaller the accelerating effect of the stray current to corrosion, the lower the frequency and the greater the acceleration. (2) the corrosion rate increases with the increase of the AC voltage. The greater the AC voltage is, the more serious the corrosion of Q235 steel is, the linear relationship between the added AC potential and the corrosion rate is v=0.045+0.273 [Phi]; (3) the AC stray current voltage. The corrosion potential of Q235 steel will be offset by the positive sweep process and the reverse direction of the reverse process. When the AC stray current voltage increases, the corrosion potential of the Q235 steel specimen is negatively offset when the potential is swept, and the corrosion potential of the Q235 steel specimen is positively offset when the potential sweep is swept; (4) a Q235 steel electrode under the action of the alternating circulation cycle. The reaction of the surface is divided into three stages: I: the active dissolution phase of the anode II: hydrogen evolution phase III: hydrogen evolution stage. Due to the existence of the hydrogen evolution phase, the loss of the material is smaller than the DC stray current in the same condition, but the hydrogen produced by the hydrogen evolution reaction will make the material easy to occur. The corrosion of hydrogen embrittlement is more serious; (5) when the frequency is low, a strong polarization platform is appeared near the zero current. The electrode process is mainly electrochemical polarization. When the frequency is high, the main factor is the voltage of the disappearing electrode potential, the electrochemical polarization is ignored, and the platform appears when the current is large to small. Early, when the current is from small to large, the platform appears earlier, that is, the two platforms that appear in a cycle process do not coincide. The greater the external potential, the greater the difference between the two platforms, the frequency of the platform is less than 1Hz.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG172.4

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