本文選題：無氧銅 + 腐蝕行為　； 參考：《深圳大學》2017年碩士論文

【摘要】：本文以材質(zhì)為無氧銅的燃氣熱水器近幾年來在我國北方地區(qū)使用幾個月就漏水失效為背景,采用循環(huán)伏安法與Tafel曲線分析探究了無氧銅在含有C1~-、SO_4~(2-)和CO_3~(2-)的生活用水中的腐蝕行為,通過XRD、SEM及金相顯微鏡觀察分析經(jīng)模擬浸泡腐蝕試驗后的銅管表面形貌與腐蝕產(chǎn)物,來研究換熱器的溫度與工況對銅腐蝕行為的影響。研究討論結果如下:1)在國家生活衛(wèi)生用水標準GB5749-2006的規(guī)定范圍內(nèi)C1~-、SO_4~(2-)和CO_3~(2-)對無氧銅都有侵蝕性,C1~-與SO_4~(2-)的侵蝕性最強。C1~-的濃度增加會加速銅全面腐蝕,會促進銅的點蝕形核,但不利于點蝕的發(fā)展;SO_4~(2-)的濃度增加對銅的全面腐蝕影響并不大,易引起點蝕;CO_3~(2-)濃度的增加可加速銅的全面腐蝕;CO_3~(2-)在低于0.01 mol/L時,濃度的增加易引發(fā)點蝕,而在CO_3~(2-)濃度大于0.03 mol/L時,濃度的增加會抑制點蝕。2)在 C1~-與 SO_4~(2-)混合體系中,C1~-濃度對銅的全面腐蝕起著主導作用,C1~-濃度的增加會促進銅的全面腐蝕;當C1~-的濃度低于0.005 mol/L時,SO_4~(2-)的增加會大大增強銅的點蝕傾向,引起點蝕的發(fā)生;當C1~-濃度大于0.03 mol/L時,C1~-濃度將對銅點蝕行為起主導作用。在C1~-與CO_3~(2-)混合體系和SO_4~(2-)與CO_3~(2-)混合體系中,當溶液中CO_3~(2-)濃度小于0.01 mol/L時,C1~-或SO_4~(2-)的增加會加速銅的全面腐蝕,促進銅點蝕的發(fā)生;而當溶液中CO_3~(2-)濃度大于0.03 mol/L時,溶液中銅的腐蝕腐蝕行為主要由CO_3~(2-)濃度來控制,CO_3~(2-)濃度的增加會抑制銅點蝕的發(fā)生。3)在20~50℃范圍內(nèi),溫度的上升會加速銅的全面腐蝕,促進銅表面的點蝕形核,但是會抑制點蝕的發(fā)展。北方地區(qū)的生活用水雖達到了GB5749-2006的要求,但是由于其SO_4~(2-)含量較高,所以會使無氧銅有很大的點蝕傾向,易引發(fā)點蝕。4)無氧銅在流水條件下的腐蝕要比靜水條件下的嚴重。無氧銅在溫度為30℃時腐蝕較為嚴重,易發(fā)生點蝕;30℃條件下無氧銅表面因均勻腐蝕所形成的腐蝕產(chǎn)物層脆弱保護性差,易于被擊穿,形成大陰極小陽極的腐蝕電池而引發(fā)點蝕。5)晶粒尺寸對無氧銅的腐蝕行為的影響不大;表面裂紋的存在會加快銅的全面腐蝕與增大其點蝕敏感性;水質(zhì)對無氧銅腐蝕性的影響要大于表面裂紋的影響。6)熱交換器的失效原因為盤管發(fā)生點蝕穿孔。熱交換器盤管上點蝕孔分布在溫度為30℃的區(qū)域,這與模擬腐蝕浸泡實驗所得出無氧銅在溫度為30℃時易發(fā)生點蝕的結論相一致。7)影響無氧銅腐蝕行為的兩個主要因素是水質(zhì)與均勻腐蝕所形成的腐蝕產(chǎn)物層;無氧銅的均勻腐蝕與點蝕會同時進行,均勻腐蝕的腐蝕產(chǎn)物層不均勻與缺陷的存在都會促進點蝕的發(fā)生。同時水質(zhì)中含有較高的SO_4~(2-)時;會大大提高無氧銅的點蝕敏感性,進一步促進無氧銅發(fā)生點蝕。
[Abstract]:In this paper, based on the leakage failure of gas water heaters made of oxygen free copper in the north of China in recent years, the corrosion behavior of oxygen free copper in domestic water containing C _ (1) -C _ (so _ 4) and CO _ (3) is investigated by cyclic voltammetry and Tafel curve analysis. The surface morphology and corrosion products of copper tube after simulated immersion corrosion test were observed and analyzed by XRDX SEM and metallographic microscope to study the effect of heat exchanger temperature and working condition on copper corrosion behavior. The results of the study are as follows: (1) within the scope of the National Standard for domestic Sanitary Water (GB5749-2006), the concentration of C _ (1) and C _ (1) (2) and COSP _ (2) are both corrosive to oxygen-free copper (and so _ (4) ~ (2) the concentration of the most corrosive copper,. C _ (1) ~ (-), will accelerate the overall corrosion of copper and will promote the pitting nucleation of copper. However, the increase in the concentration of so _ 4 / T _ 2) does not have a great effect on the overall corrosion of copper. The increase in the concentration of COT _ 3 / T _ 2-can accelerate the overall corrosion of copper. () when the concentration is lower than 0. 01 mol/L, the increase of the concentration will easily lead to pitting corrosion. When the concentration of CO _ 3O _ 2 is greater than 0.03 mol/L, the increase of concentration will inhibit the pitting corrosion. 2) in the mixed system of C _ (1) and S _ (4) O _ (2), the concentration of C _ (1) ~ (-) plays a leading role in the overall corrosion of copper. The increase of concentration of C _ (1) ~ (-) can promote the overall corrosion of copper. When the concentration of C1O- is lower than 0.005 mol/L, the increase of the concentration of so _ 4 ~ + _ 2) will greatly enhance the pitting corrosion tendency of copper and cause the occurrence of pitting corrosion, and when the concentration of C _ (1) ~ (-) is greater than 0.03 mol/L, the concentration of C _ (1) ~ (-) will play a leading role in the pitting corrosion behavior of copper. In the C _ 1 / C _ 3 / C _ T _ 2 / C _ _ _ The corrosion behavior of copper in the solution is mainly controlled by the concentration of COSP _ 3 ~ (2). The increase of the concentration of CO _ 3 / C _ (2) will inhibit the occurrence of copper pitting corrosion. 3) in the range of 20 ~ 50 鈩，

本文編號：1818059