【作者】 杨富宝；

【导师】 吴希俊； 罗伟；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2005， 硕士

【摘要】 本文用动电位极化法,研究了SO42-、PH值、温度T和Cl-等对由惰性气体凝结-原位温压法制备的纳米晶Cu(平均晶粒尺寸为21nm)的阳极极化行为的影响,并用场发射扫描电镜和X-射线能量散射谱(EDS)研究了纳米晶Cu的腐蚀产物的形貌和成份。研究结果表明,SO42-、PH值、温度T和Cl-对纳米晶Cu的阳极极化行为有着重要影响。随着SO42-浓度增大,纳米晶Cu的致钝电流逐渐增大,logi随[SO42-]呈线性变化,其斜率为0. 01158;而纳米晶Cu的致钝电位,则随着SO42-浓度增大而降低。本文提出了“静电离子团”模型解释纳米晶Cu阳极极化曲线上的“斜率转折点”现象;并提出纳米晶铜在Na2SO4溶液中的电极反应过程,据此推导出电极动力学表达式。随着Na2SO4溶液PH值降低,纳米晶Cu的致钝电流线性增大,logi=-0. 0287PH+0. 25。H+浓度的增加干扰了电极表面氧化膜的生成过程,从而增大了阳极溶解速率。Logi随温度的倒数呈线性变化,即logi=-669. 94(1/T)+2. 4388。温度对纳米晶Cu阳极极化行为的影响机制用Arrhenius方程进行了解释。纳米晶Cu在1. 5%NaCl溶液中腐蚀时,阳极电流出现振荡现象,这与Cu(Ⅱ)的非线性溶解过程有关。纳米晶Cu在Na2SO4溶液中的腐蚀产物主要为Cu2O立方晶体,其尺寸与温度有关。当Na2SO4溶液的温度由25℃升高至40℃时,电极表面紧密堆积的Cu2O立方晶体的尺寸由150-230nm减小到50nm。纳米晶Cu在1%NaCl溶液中的腐蚀产物主要为CuCl和Cu2O晶体。电极表面凹凸不平,存在着腐蚀较为严重的“沟槽”。“沟槽”顶部,中部和底部的腐蚀产物的形状和尺寸均不相同。更多还原

【Abstract】 The influence of sulfate ions, PH, temperature and chloride ions on the anodic polarization behaviour of nanocrystalline copper (nano-Cu), prepared by an inert gas condensation and in-situ warm compacting technique, was investigated using a potentiodynamic polarization method. Meanwhile, the field emission gun scanning electron microscopy and x-ray energy dispersive spectroscopy were used to characterize the morphology and chemical composition of corrosion products. The results showed that the sulfate ions, chloride ions, PH and temperature play important role on the anodic polarization behaviour of nano-Cu. In the case of Na2SO4 solution, the critical current increases with increasing sulfate ion concentration and the slope of the log i vs sulfate ion concentration is 0.01158. However, the critical potential decreases as sulfate ion concentration increases. A model of "electrostatic ion clusters" was proposed for interpreting the "slope pivotal point" occurring on the anodic polarization curves. In addition, the corrosion mechanism of nano-Cu in Na2SO4 solution and the kinetic equation were proposed. The variation of log i with PH fits the following linear relation, logi=-0.0287PH +0.25. An increasing H+ concentration disturbs the formation of oxidation film, resulting in an increased rate of electrodissolution .The variation of logi vs 1/T could be described as log i= -669.94(l/T)+2.4388. On the base of Arrenhenius equation, the influence of temperature on the anodic polarization behaviour was analyzed. In the case of NaCl solution the current oscillation of nano-Cu electrode in 1.5%NaCl solution was observed and concerned with the non-linear Cu(II) dissolution processes. The main corrosion products of nano-Cu in Na2SO4 solution are Cu2O cubic crystallites with different size, which is dependent on the temperature of Na2SO4 solution. For example, the size of the Cu2O cubic crystallites closely stacked on the electrode surface varies from about 200 nm to about 50nm when the temperature of Na2SO4 increases from 25 ℃ to 40 ℃. On the other hand, the main corrosion products of nano-Cu in NaCl solution are CuCl and Cu2O crystallites. The grooves appear on the surface of electrode, indicating that these areas are heavily corroded. The shape and size of CuCl and Cu2O crystallites are different at the different site of the top, middle and bottom of these grooves.更多还原