铜在KCl溶液中电化学腐蚀过程的元胞自动机模拟研究

铜电极在KCl电解质溶液中的电化学腐蚀已有循环伏和红外光谱电化学研究，然而，腐蚀过程的动力学和机理还不十分清楚．本文以SCILAB自由软件编程的元胞自动机方法模拟了该腐蚀过程的动力学，与实验结果一致，结合红外光谱、量子化学计算结果，进一步在分子尺度上探讨铜在实验条件下的腐蚀过程的机理：腐蚀动力学曲线在较短时间（〈200...     

用于铜电化学机械抛光的羟基乙叉二膦酸基电解液反应机理研究

在铜电化学机械抛光(ECMP)工艺中,羟基乙叉二膦酸(HEDP)可与其他水处理剂协同抑制电解并使金属表面光滑,而传统的操作电位低于4 V(vs.SCE)限制了反应过程中的材料去除率。为解决此问题,在较高电位下对铜进行动电位腐蚀、静电位腐蚀和ECMP试验,研究工艺可行性并探索电解液的反应机理。结果表明:在6 V(vs.SCE)下,能最大程度地提高铜片的表面粗糙度和材料去除率。反应机理推测:从工作电极电离得到的铜离子与两个HEDP分子反应生成配位化合物[CuL2]6-后与K+结合形成配位化合物[KCuL2]5-。     

电化学氧化对碳纤维表面电化学性质的影响

碳纤维表面呈现化学惰性,缺乏活性官能团,限制了碳纤维作为电化学分析电极的应用.目前,许多手段被用于碳纤维的表面改性处理.采用电化学氧化方法,在磷酸溶液中对碳纤维进行了处理,并进行了红外光谱和循环伏安试验.结果发现:处理后碳纤维的表面接上了活性官能团,大量活性碳原子被剥离出来.在K4Fe(CN)6加KCl、FeSO4加HClO4两组混合溶液体系中的电化学响应明显改善,适合作为电化学分析电极.     

铜在雨水中的腐蚀行为电化学研究

采用电化学动电位扫描和交流阻抗研究了铜在模拟斯 德哥尔摩雨水中的腐蚀行为.铜表面存在少量腐蚀产物时，铜在雨水中的腐蚀主要由电化学 机制控制；随着腐蚀产物在铜表面的大量生成和沉积，存在腐蚀产物的区域和不存在腐蚀产 物的区域，形成了电偶腐蚀电池，腐蚀产物区为阴极.     

大气环境中SO_2和H_2S对铜的电化学腐蚀行为比较

采用电化学阻抗谱和极化曲线比较研究了含有SO2或H2S的大气环境中铜电极在液膜中的电化学腐蚀行为。结果显示,随着SO2或H2S含量的增加,铜电极的电荷转移电阻和膜电阻减小,双电层电容和膜电容增大,同时铜电极的腐蚀电位负移,腐蚀电流密度增大,大气中的SO2或H2S可能通过改变铜电极表面腐蚀产物的组成,降低电极反应阻力,促进铜的阳极溶解过程,加速铜的腐蚀。在相同质量浓度下,两种腐蚀性气体中H2S对铜的侵蚀性更大。     

金属在薄层液膜下电化学腐蚀电池的设计

设计了用于研究金属材料在薄层液膜下腐蚀行为的参比电极后置式三电极电化学测量电池,并用此研究了铜在薄层液膜下的阳极极化行为,用双电极电解池研究了铜在薄层液膜下的交流阻抗行为。结果表明：薄层液膜（0.5mol/LHCl 0.25mol/LNa2SO4电解质）厚度的减小,影响了Cu腐蚀的阳极过程,使Cu的阳极溶解由Tafel区转向极限扩散电流区,腐蚀机制发生了变化,增大了Cu的自腐蚀电位。     

N80碳钢CO2／HAc腐蚀电化学过程

采用动电位扫描、恒电位极化和电化学交流阻抗测试技术,研究了乙酸(HAc)对N80碳钢在50℃、饱和CO2的1%NaCl溶液中的电化学腐蚀行为的影响,并讨论了阴极、阳极的反应机理.研究表明:HAc能够直接在电极表面还原,使阴极极限电流增加.HAc未改变阳极反应机理,但能够加速中间产物的形成/溶解过程,从而加速阳极溶解过程.在饱和CO2溶液体系,乙酸盐易与碳酸生成HAc,而参与电化学反应.因此,无论是HAc还是乙酸盐均能够加速N80碳钢电极的CO2腐蚀.     

用于大气环境的电化学传感器的腐蚀性能研究

构造了一种用于监测大气腐蚀的金属材料的电化学传感器,分别选用低合金钢和铜导电漆两种具有不同电位的金属材料,基于电偶腐蚀原理组成传感器的两个电极,两个电极之间以薄的有机硅绝缘膜相隔,传感器与大气薄液膜介质形成一个电化学腐蚀系统。在两个金属电极之间有液膜产成时,就会形成一个腐蚀电池,并产生电偶腐蚀电流,通过监测这种电偶电流以反映环境中材料的腐蚀状态。本文采用新型电化学传感器,同时借助电化学工作站和高精度电子天平,研究了绝缘膜厚度、液膜厚度、温度、相对湿度及阴阳极面积比等因素对电偶电流的影响规律,并证实了新型电化学传感器具有很高的灵敏度,可用于薄液膜下大气腐蚀的监测。     

扫描电化学显微镜对铁自组装膜的电化学表征

    用扫描电化学显微镜（SECM）的线扫描的方法研究咪唑啉分子吸附在铁的表面形成的自组装单分子膜(SAMs).采用恒高度工作模式,用基底产生/探头收集的原理探讨发生在探头针尖与基底间隙的化学动力学过程和对表面浓度进行检测.空白的铁电极和组装咪唑啉的铁电极在0.1 mol/L HClO₄的峰电流的值分别是-1.67165e-9A和-2.146e-10A.结果表明,组装咪唑啉分子后探头具有更低的电流,其原因在铁电极表面形成的SAMs膜抑制了电极在溶液中发生的氧化还原反应,阻碍了电荷转移过程,抑制了铁基底的溶解.     

硼铜低碳钢在氯离子环境中的耐蚀性能

为考察硼铜低碳钢的腐蚀规律,采用盐雾腐蚀试验和电化学试验研究了硼铜钢的腐蚀行为,结合X射线衍射(XRD)和傅里叶红外光谱(FTIR)对腐蚀产物进行了分析.结果表明:硼与铜复合作用的钢耐蚀性超过铜硼单独添加实验钢,而硼铜分别添加的实验钢耐蚀性相差不明显;3种钢阳极电流密度的变化规律一致,随腐蚀时间延长,阳极电流密度逐渐减小;硼和铜复合添加增强实验钢的阳极极化作用.     

Corrosion-induced copper runoff from naturally and pre-patinated copper in a marine environment

Corrosion-induced copper runoff has been monitored for copper sheet, naturally patinated copper and pre-patinated copper, with and without surface treatments, in a marine environment during one year. The study comprises solution measurements on total copper runoff rates, sulphates and chlorides released from the patina, and parallel surface analytical studies on patina formation, combined with electrochemical impedance measurements on changes in barrier properties during exposure. Bioassay tests and model predictions were applied to elucidate copper bioavailability at the immediate release situation. The runoff rate of copper was significantly lower compared to the corrosion rate throughout the exposure period. At comparable rain quantities, copper runoff rates were significantly lower at the marine site compared to similar data obtained in an urban environment. The bioavailable concentration of released copper was significantly lower compared to the total copper concentration.     

An in‐situ FT‐IR investigation of the anodic behaviour of WC‐Co hardmetal

An in‐situ FT‐IR spectroelectrochemical and voltammetric study of the corrosion of a WC‐Co hardmetal grade is reported in this communication. A slightly acidic sulphate solution is considered. The potential‐ and time‐dependent anodic formation of CO₂ and Co(OH)₂ can be followed with the variation of the vibrational spectra. The formation of CO₂ occurs at the same potential at which tungsten oxidation starts to be detected and the breakdown of passivity can be observed by electrochemical methods. Our results suggest that a threshold potential exists for the oxidation of WC in WC‐Co, giving rise to the concomitant oxidation of tungsten and carbon at more noble potentials than those typical for the oxidation of the individual elements.     

Zum Einfluß von Chloracetylchloriden und Chloressigsäuren auf die Korrosion metallischer Werkstoffe in Trichlorethylen und Perchlorethylen

The influence of chloroacetyl chlorides and chloroacetic acids on the corrosion of metals in trichloroethylene and tetrachloroethylene The corrosive behaviour of selected stainless steels, nickel, copper and zinc materials in trichloroethylene and tetrachloroethylene containing dichloroacetic acid and dichloroacetyl chloride or trichloroacetic acid and trichloroacetyl chloride in concentrations between 100 and 10000 ppm from room temperature to the boiling point was investigated. NiCu 30 Fe was resistant in all systems investigated. Only tetrachloroethylene containing trichloroacetyl chloride corroded the stainless steels. Corrosion rates up to 0.07 mm/y and a tendency towards pitting corrosion were detected. Trichloroethylene containing dichloroacetic acid proofed aggressive towards Cu-DHP, CuZn 15, and CuSn 6. Corrosion rates between 0.14 and 0.32 mm/y were observed. Tetrachloroethylene containing trichloroacetic acid was far less corrosive towards copper materials. In tetrachloroethylene, containing trichloroacetyl chloride, of the copper materials investigated, CuZn 15 and CuAl8 were relatively strongly attacked (corrosion rate 0.10 mm/y). Of the investigated materials, Zn 99.95 was the least resistant to corrosion. Solutions containing acids and acid chlorides proofed to be the most aggressive with corrosion rates between 0.56 and 0.66 mm/y. Some corrosion products, developed on the metal surfaces, were analysed.     

腐蚀金属电极行为与其界面性能关系研究方法及发展趋势

概括了腐蚀电化学理论研究的现状及发展趋势;从电极反应特点入手,论述了腐蚀界面性能对电极反应行为的决定作用;评述了腐蚀界面性能的主要研究方法,综合了腐蚀界面性能研究的最新结果。     

The influence of adenine on corrosion of copper in chloride solutions

The influence of the concentration of adenine (AD) on the corrosion and the spontaneous dissolution of copper in 1.0 M NaCl solutions of pH 6.8 was studied. The investigations involved electrochemical polarization methods as well as weight loss measurements, quartz crystal microbalance (QCM) techniques and scanning electron microscopy (SEM). The inhibition efficiency increases with an increase in the concentration of AD. An adherent layer of inhibitor is postulated to account for the protective effect. The adsorption of adenine has been found to occur on the surface of copper according to the Langmuir isotherm. The values of standard free energies of adsorption suggest chemical adsorption of AD on copper surface. The use of adenine can effectively prevent various new installations made of copper and exposed to the action of aqueous solutions of chlorides from corrosion damage.     

Localized attack of copper and brass in tap water: the effect of Pseudomonas

The presence of Pseudomonas fluorescens in artificial tap water (ATW) affects the composition of the oxide layer and the susceptibility to pitting corrosion of copper and 70/30 brass. The surface layer was investigated by means of a combination of electrochemical and spectroelectrochemical techniques involving cyclic voltammograms, potentiodynamic reduction curves, anodic polarisation curves, weight-loss tests and reflectance spectroscopy.In the sterile conditions the mass loss is lower in brass than in copper while the presence of bacteria enhances the attack in brass. Dezincification in inoculated electrolyte was revealed by microscopic observation, as well as by potentiodynamic reduction curves. Zn dissolution was also supported by spectroscopic evidence.Slow-rate voltamperometric curves were used to determine potential values characteristic of localized corrosion. In the presence of bacteria, the pitting potential moves towards more positive values for both materials but the difference between the repassivation and the pitting potential increases. Bigger and deeper pits can be seen in the presence of microorganisms.     

An in situ optical second harmonic generation study of carbon steel in contact with an alkaline aqueous solution containing glutamic acid

In this paper we report a spectroelectrochemical investigation—relevant to the elucidation of rebar corrosion processes—based on in situ optical second‐harmonic generation spectroscopy. We studied the corrosion behaviour of a carbon steel electrode in contact with an alkaline aqueous solution—simulating the electrolyte of freshly prepared cement paste—containing glutamic acid, a candidate corrosion inhibitor 1 . The non‐linear time‐dependent optical response to exciting radiation at 1064 nm has been recorded as a function of applied potential. This approach allows to obtain detailed information regarding the dynamic electronic structure of the corrosion interface, which is not available from other electrochemical or spectroelectrochemical approaches.     

Role of chlorides in hot corrosion of a cast Fe–Cr–Ni alloy. Part I: Experimental studies

High alloy stainless steels are often used in corrosive, high temperature applications because they form a protective, adherent Cr₂O₃ scale. When the environment in such applications includes condensed molten salts, especially alkali sulfates and alkali chlorides, these alloys are likely to undergo hot corrosion, even at moderate temperatures compared to their typical maximum application temperature. The chemical (or electrochemical) reactions and transport modes for hot corrosion in a system involving a multi-component alloy and a multi-component salt are complex, but some insight can be gained with the help of a multi-component thermochemical model to identify major reactions. The present work consists of two parts: (a) experimental measurements of hot corrosion rates and characterization of corrosion products on a commercial, cast super-duplex stainless steel (HH), which result from exposure to thin deposits of a mixture of alkali sulfates and alkali chlorides, and (b) an evaluation of possible corrosion reactions by a multi-component thermochemical model. In laboratory hot corrosion tests alloy coupons experienced rapid oxidation rates, penetration of the oxide scale, scale blistering, and scale spallation (on cooling). Compared to simple air oxidation, alkali sulfate deposits increased the corrosion rate by a factor of about 200, but mixtures of alkali sulfate and alkali chloride increased the rate by about 20,000 times. A principal goal of the study was to identify the role of alkali chlorides in accelerating hot corrosion.     

Corrosion Properties of NdFeB Magnets Coated by a Ni/Cu/Ni Layer in Chloride and Sulfide Environments

In this study, the corrosion behavior of a permanent magnetic alloy, Nd-Fe-B, coated by a triple layer of nickel-copper-nickel was studied. The corrosion resistance was investigated by (i) flux tests, carried out at 90 °C in an atmosphere containing chlorides or at 70 °C containing sulfides, (ii) electrochemical impedance spectroscopy (EIS), and (iii) potentiodynamic polarization tests, carried out in solution at different temperatures (0-90 °C) containing chlorides or sulfides. The morphology and the composition of the samples and the corrosion products were analysed by optical microscopy and scanning electron microscopy, equipped with an energy dispersive x-ray detector. The magnetic properties were characterized by magnetic flow measurements. The flux tests indicated that the triple layer of coating provided a greater corrosion resistance in atmosphere containing chlorides than the one with sulfides. The potentiodynamic and the EIS tests showed that the corrosion rate increased with temperature. The magnetic properties of the sample remained unchanged after exposure to the aggressive environment.