本文選題：耐腐蝕鋼筋 + 顯微組織　； 參考：《安徽工業(yè)大學(xué)》2017年碩士論文

【摘要】：近年來,隨著跨海大橋、海底隧道等工程的建設(shè)以及海港、海洋工程等的快速發(fā)展,越來越多的基礎(chǔ)設(shè)施需要在海洋環(huán)境中建設(shè),而普通鋼筋不能滿足耐蝕性能的要求,耐腐蝕鋼筋在這種情況下應(yīng)運而生。耐腐蝕鋼筋具有較好的耐蝕性和較低的成本,在海洋環(huán)境中有很好的應(yīng)用前景。本文在模擬海洋環(huán)境下采用周浸實驗,研究了具有不同組織和合金元素含量的鋼筋的腐蝕速率隨時間的變化規(guī)律;用光學(xué)顯微鏡、掃描電鏡、XRD等方法研究了鋼筋銹層及物相構(gòu)成隨時間的演變;采用動電位極化曲線和阻抗譜探討了鋼筋耐腐蝕的機理。結(jié)論如下:在3.5%NaCl模擬的海洋環(huán)境中,相同成分的F+B鋼筋的自腐蝕電位高于F+P鋼筋,前期平均腐蝕速率明顯低于F+P鋼筋;中期F+B鋼筋平均腐蝕速率的穩(wěn)定時間較F+P鋼筋早,后期兩種鋼筋的平均腐蝕速率相近。在3.5%NaCl溶液中浸泡較長時間后的交流阻抗值相當(dāng)。表明了兩類不同顯微組織對鋼筋基體耐蝕性能的影響只停留在穩(wěn)定銹層形成之前。合金元素Cr、Mn含量更高的鋼筋極化曲線出現(xiàn)了不穩(wěn)定的鈍化膜,Cr、Mn的加入提升了鋼筋前期的點蝕傾向,初期平均腐蝕速率明顯較含Cr、Mn較低的鋼筋高,長期浸泡的阻抗值明顯較大,腐蝕后期的平均腐蝕速率下降明顯。而單獨加入Cr元素(1.26%)的鋼筋在整個腐蝕周期內(nèi)的平均腐蝕速率明顯的較低,低于低Cr(0.04%)鋼筋,高Cr元素含量的鋼筋基體自腐蝕電流明顯較低,且出現(xiàn)明顯鈍化現(xiàn)象,前期的平均腐蝕速率平緩,實驗中Cr、O元素通過在裂紋和孔洞處富集形成化合物而降低基體的平均腐蝕速率,后期平均腐蝕速率有下降的趨勢。腐蝕過程中沒有發(fā)生Mn元素明顯的富集現(xiàn)象,表明了在3.5%NaCl溶液環(huán)境情況下Mn元素對腐蝕速率的的影響不大。實驗過程中鋼筋的銹層厚度都是隨著腐蝕周期的延長而逐漸加厚,銹層中主要物相由Fe3O4、γ FeOOH和α FeOOH組成,還可能在前期有少量的NaCl侵入。腐蝕后期棉絮狀α FeOOH物相的生成對平均腐蝕速率的降低起重要作用,顯微組織類別和合金元素含量都對銹層中物相的變化有著一定的影響,可通過人工控制顯微組織類型和控制合金元素添加量的方法來改善鋼筋耐蝕性能。
[Abstract]:In recent years, with the construction of cross-sea bridges, subsea tunnels and other projects, as well as the rapid development of seaports and ocean engineering, more and more infrastructure needs to be built in the marine environment, but ordinary steel bars can not meet the requirements of corrosion resistance. Corrosion resistant steel bar emerges as the times require in this case. Corrosion resistant steel bar has good corrosion resistance and low cost, and has a good application prospect in marine environment. In this paper, the variation of corrosion rate of steel bars with different microstructure and alloy element content with time was studied by means of cycle immersion experiment in simulated marine environment, and the corrosion rate of steel bars with different microstructure and alloying elements was studied by optical microscope. The evolution of rust layer and phase composition over time was studied by SEM and XRD, and the mechanism of corrosion resistance of steel bar was investigated by potentiodynamic polarization curve and impedance spectrum. The conclusions are as follows: in the marine environment simulated by 3.5 NaCl, the self-corrosion potential of the same composition FB steel bar is higher than that of the F-P steel bar, and the average corrosion rate in the early stage is obviously lower than that of the F-P steel bar. The average corrosion rate of F B steel bar is earlier than that of F P steel bar in the middle period, and the average corrosion rate of the two kinds of reinforcement is similar in the later stage. After soaking in 3.5% NaCl solution for a long time, the AC impedance is equal. The results show that the effect of two kinds of microstructure on the corrosion resistance of steel matrix only stays before the formation of stable rust layer. The polarization curve of steel bar with higher Cr-Mn content of alloy element appears unstable passivation film and Cr-Mn increase the pitting corrosion tendency of steel bar in the early stage, the average corrosion rate in the initial stage is obviously higher than that in the steel bar with lower Cr-Mn content, and the impedance value of long-term immersion is obviously higher than that of the steel bar with lower Cr-Mn content. The average corrosion rate decreased obviously in the late stage of corrosion. However, the average corrosion rate of steel bars added with Cr (1.26%) in the whole corrosion cycle is obviously lower than that of low Cr (0.04%) steel bars, and the self-corrosion current of steel bars with high Cr content is obviously lower, and the passivation phenomenon is obvious. The average corrosion rate in the early stage was gentle. In the experiment, the average corrosion rate of the matrix was decreased by the accumulation of Cr-O in the cracks and pores, and the average corrosion rate decreased in the later stage. There was no obvious enrichment of mn in the corrosion process, which indicated that mn had little effect on the corrosion rate in 3.5 NaCl solution. In the process of experiment, the thickness of the rust layer of steel bars is gradually thickened with the extension of corrosion cycle. The main phases in the rust layer are composed of Fe _ 3O _ 4, 緯 -O _ (OH) and 偽 -Fe _ (OOH), and may be invaded by a small amount of NaCl in the early stage. In the later stage of corrosion, the formation of the cotton-like 偽 -FeOOH phase plays an important role in the decrease of the average corrosion rate, and the microstructure and the content of alloying elements have a certain influence on the changes of the phase in the rust layer. The corrosion resistance of steel bars can be improved by manually controlling the microstructure type and controlling the amount of alloying elements.
【學(xué)位授予單位】：安徽工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG142.1

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