發(fā)布時間：2019-05-25 04:28

【摘要】：超細(xì)晶材料與粗晶材料相比具有優(yōu)良的力學(xué)性能,但對于其耐蝕性還有待進(jìn)一步研究。本文采用等通道轉(zhuǎn)角擠壓技術(shù)(Equal Channel Angular Pressing,簡稱ECAP)制備了超細(xì)晶Cu-Cr-Zr合金,并對其組織性能進(jìn)行了相應(yīng)的分析,利用電化學(xué)工作站通過Tafel極化曲線以及電化學(xué)交流阻抗譜(EIS)重點(diǎn)研究ECAP變形道次、ECAP變形后的時效處理、氯離子濃度、添加硫離子、溫度以及酸堿對超細(xì)晶Cu-Cr-Zr合金腐蝕行為的影響,取得的主要研究結(jié)果如下:(1)經(jīng)過ECAP變形后的Cu-Cr-Zr合金,晶粒尺寸隨著道次的增加不斷減小,粗晶時晶粒尺寸約為50~80μm,ECAP變形8道次后晶粒尺寸約為150~200nm。(2)研究不同晶粒度Cu-Cr-Zr合金在0.5mol/L氯化鈉溶液中的腐蝕行為,結(jié)果表明隨著ECAP變形道次的增加,晶粒度減小,其腐蝕電流密度減小,粗晶時的自腐蝕電流密度為2.26μA·cm~(-2),ECAP變形8道次后減小為0.54μA·cm~(-2);通過對其等效電路擬合,擴(kuò)散過程的傳遞電阻隨道次的增加而增大,由粗晶時的9746Ω增大到ECAP變形8道次的14130Ω,表明電荷在腐蝕介質(zhì)和電極間轉(zhuǎn)移變難,合金的耐蝕性提高。(3)在0.5mol/L氯化鈉溶液中,研究不同熱處理狀態(tài)下的Cu-Cr-Zr合金的腐蝕行為,發(fā)現(xiàn)在粗晶狀態(tài)下,經(jīng)過時效處理試樣的腐蝕性能較好,其自腐蝕電流密度由2.26μA·cm~(-2),經(jīng)時效處理后減小到2.00μA·cm~(-2);而在ECAP變形8道次時,未進(jìn)行時效處理試樣的耐蝕性遠(yuǎn)大于時效態(tài),時效處理后的自腐蝕電流密度由未處理的0.54μA·cm~(-2)增加到3.97μA·cm~(-2)。(4)對比分析在不同氯離子濃度下Cu-Cr-Zr合金的腐蝕行為,結(jié)果表明隨著Cl-濃度的增加,試樣的自腐蝕電流增大,其耐蝕性減弱,同時發(fā)現(xiàn)濃度越高,濃度變化對耐蝕性的影響越不明顯;對比在0.5mol/L氯化鈉溶液中添加硫離子時Cu-CrZr合金的腐蝕規(guī)律,結(jié)果表明超細(xì)晶試樣較粗晶試樣腐蝕產(chǎn)物層更嚴(yán)密,腐蝕速度更小,耐蝕性更好,和同等條件下不含硫離子時相比,耐蝕性更好;對比分析在不同溶液溫度下超細(xì)晶Cu-Cr-Zr合金的腐蝕行為,發(fā)現(xiàn)隨著溫度的升高,耐蝕性降低。(5)研究Cu-Cr-Zr合金在酸堿中的腐蝕規(guī)律,發(fā)現(xiàn)在鹽酸溶液中,試樣的自腐蝕電流密度隨溶液濃度的增大而增大,材料的耐蝕性變差;在NaOH溶液中則恰恰相反,試樣的自腐蝕電流密度隨溶液濃度的增大而減小,材料的耐蝕性增強(qiáng)。且在相同溶液中,超細(xì)晶試樣較粗晶試樣的自腐蝕電流密度更小,顯示出較好的耐蝕性。
[Abstract]:Compared with coarse grain materials, ultra-fine grain materials have excellent mechanical properties, but the corrosion resistance of ultra-fine grain materials needs to be further studied. In this paper, ultra-fine grain Cu-Cr-Zr alloy was prepared by equal channel angular extrusion (Equal Channel Angular Pressing, (ECAP), and its microstructure and properties were analyzed. Tafel polarization curve and electrochemical AC impedance spectroscopy (EIS) were used to study the deformation pass of ECAP, aging treatment after ECAP deformation, chloride ion concentration and sulfur ion addition. The effects of temperature and acid and base on the corrosion behavior of ultra-fine grain Cu-Cr-Zr alloy are as follows: (1) the grain size of Cu-Cr-Zr alloy after ECAP deformation decreases with the increase of pass. The grain size is about 50 ~ 80 渭 m when coarse grain is about 50 ~ 80 渭 m, and the grain size is about 150 脳 200 nm after 8 passes of ECAP deformation. (2) the corrosion behavior of Cu-Cr-Zr alloy with different grain size in 0.5mol/L sodium chloride solution is studied. The results show that with the increase of ECAP deformation pass, When the grain size decreases, the corrosion current density decreases, and the self-corrosion current density is 2.26 渭 A cm~ (- 2), ECAP) after 8 passes deformation to 0.54 渭 A cm~ (- 2). By fitting the equivalent circuit, the transfer resistance of diffusion process increases with the increase of pass, from 9746 惟 in coarse grain to 14130 惟 in 8 passes of ECAP deformation, which indicates that the transfer of charge between corrosion medium and electrode is difficult. The corrosion resistance of the alloy was improved. (3) the corrosion behavior of Cu-Cr-Zr alloy under different heat treatment conditions was studied in 0.5mol/L sodium chloride solution. It was found that the corrosion properties of the samples treated by aging were better in coarse grain state. The self-corrosion current density decreases from 2.26 渭 A cm~ (- 2) to 2.00 渭 A cm~ (- 2) after aging treatment. When the ECAP deformation is 8 passes, the corrosion resistance of the sample without aging treatment is much greater than that of the aging state. The self-corrosion current density after aging treatment increased from 0.54 渭 A cm~ (- 2) to 3.97 渭 A cm~ (- 2). (4). The corrosion behavior of Cu-Cr-Zr alloy at different chloride ion concentrations was compared and analyzed. The results show that with the increase of Cl- concentration, the self-corrosion current of the sample increases and its corrosion resistance weakens. At the same time, it is found that the higher the concentration is, the less obvious the effect of concentration change on corrosion resistance is. The corrosion law of Cu-CrZr alloy when sulfur ion was added to 0.5mol/L sodium chloride solution was compared. the results show that the corrosion product layer of ultra-fine grain sample is stricter, the corrosion rate is lower and the corrosion resistance is better than that of coarse grain sample. The corrosion resistance is better than that without sulfur ions under the same conditions. The corrosion behavior of ultra-fine grain Cu-Cr-Zr alloy at different solution temperatures was compared and analyzed. It was found that the corrosion resistance of Cu-Cr-Zr alloy decreased with the increase of temperature. (5) the corrosion law of Cu-Cr-Zr alloy in acid and base was studied and found in hydrochloric acid solution. The self-corrosion current density of the sample increases with the increase of solution concentration, and the corrosion resistance of the material becomes worse. In NaOH solution, on the contrary, the self-corrosion current density of the sample decreases with the increase of solution concentration, and the corrosion resistance of the material increases. In the same solution, the self-corrosion current density of the ultra-fine grain sample is smaller than that of the coarse grain sample, which shows better corrosion resistance.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG172

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