發(fā)布時間：2018-06-06 14:22

  本文選題：交流雜散電流 + Q235鋼　； 參考：《西安理工大學(xué)》2017年碩士論文

【摘要】：隨著埋地管道、電氣化鐵路和高壓交流輸電線越來越多,使流入地下的雜散電流量越來越多,而酸性土壤的腐蝕性較強(qiáng)、交流電方向的可變性和交變頻率的不一致性,使得人們對交流雜散電流腐蝕問題的規(guī)律沒有完全認(rèn)識,至今沒有建立合理的交流雜散電流機(jī)理模型,使雜散電流腐蝕的預(yù)測,評價和防護(hù)比較困難。根據(jù)以上問題,本文以Q235鋼在酸性模擬土壤溶液中的腐蝕為研究對象,采用電化學(xué)測試,失重法,形貌分析,循環(huán)伏安曲線分析法研究了交流雜散電流對Q235鋼在酸性模擬土壤溶液中的影響規(guī)律。研究結(jié)果表明:(1)交流雜散電流加速Q(mào)235鋼在酸性土壤中的腐蝕。在模擬酸性土壤溶液中,外加電壓不變的情況下,交流頻率使Q235鋼腐蝕呈指數(shù)變化規(guī)律。在電壓一定的情況下,交流電頻率越高,交流雜散電流對腐蝕的加速作用越小,頻率越低,加速作用越大;(2)頻率不變的情況下,腐蝕速率隨交流電壓的增加而增加。施加的交流電壓越大,Q235鋼的腐蝕越嚴(yán)重,外加交流電位與腐蝕速率成v=0.045+0.273φ的線性關(guān)系;(3)交流雜散電流電壓會引起Q235鋼腐蝕電位的偏移,正掃過程和反掃過程的電位偏移方向相反。當(dāng)交流雜散電流電壓增大,電位正掃時,Q235鋼試樣的腐蝕電位發(fā)生負(fù)向偏移;電位反掃時,Q235鋼試樣的腐蝕電位發(fā)生正向偏移;(4)一個交流循環(huán)作用下的Q235鋼電極表面的反應(yīng)分為三個階段:Ⅰ:陽極的活性溶解階段Ⅱ:析氫極化階段Ⅲ:析氫控制階段。由于析氫反應(yīng)階段的存在,在相同的條件下,雖然交流雜散電流造成材料的損失量比直流雜散電流要小,但是析氫反應(yīng)產(chǎn)生的氫氣會使材料容易發(fā)生氫脆現(xiàn)象,因此腐蝕更嚴(yán)重;(5)在頻率較低時,在電流為零附近出現(xiàn)了一個強(qiáng)極化的平臺,電極過程以電化學(xué)極化為主,當(dāng)頻率較高時,這種平臺消失電極電位以外電壓為主要因素,電化學(xué)極化被忽略,電流由大向小進(jìn)行時,平臺出現(xiàn)的較早,在電流由小向大時,平臺出現(xiàn)的也較早,即在一個循環(huán)過程中,出現(xiàn)的兩個平臺不相重合。外電位越大,這兩個平臺相差越大,出現(xiàn)平臺的頻率小于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.
【學(xué)位授予單位】：西安理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG172.4

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本文編號：1986914