焊接接头微区电位测试装置的研制

设计并制造了钨微电极扫描测试装置，由微参比电极 、自动扫描机械装置、电解池、A/D转换器和计算机组成.整套装置简易可行，能够在极缓 慢速度下对微区电位进行自动扫描，评价焊接接头表面电化学不均匀性的程度.实验表明， 在酸性环境下，钨微电极也具有良好的稳定性与重现性，可以用于微区腐蚀电位的测试.     

Cl~-浓度对镁-铝合金β相模型合金腐蚀电化学行为的影响

对镁-铝合金β相模型合金在不同浓度的Cl~-溶液环境中的腐蚀电化学行为进行研究.结果表明,随着Cl~-浓度的增加,β相的自腐蚀电位依次降低.但β相与α相之间的电位差没有随Cl~-浓度的增加递增.β相在不同浓度的Cl~-溶液中均能发生钝化,随Cl~-浓度的增加点蚀击破电位降低,相应表面膜中含Mg的腐蚀产物种类也增多.在不同浓度Cl~-溶液环境中,β相模型合金的腐蚀电化学结果可以揭示β相的微电偶作用.     

印刷电路板Cu／焊锡界面早期局部腐蚀的扫描微参比电极测量

应用扫描微参比电极（SMRE）技术,对NaCl溶液中印刷电路板Cu／焊锡界面局部腐蚀早期表面微区电位分布进行了测量。结果表明,在0．5mol／LNaCI溶液中,焊锡电极电位基本稳定在-0．47V（SCE）附近,纯铜电极的电位稳定在-0．19V（SCE）附近,两者差别较大;Cu／焊锡浸入0．5mol／LNacl溶液中,前...     

扫描微电极法测量金属微区腐蚀电位电流分布——Ⅰ 扫描微电极测量系统

扫描微电极法测定金属微区腐蚀电位及电流密度分布是研究金属局部腐蚀的重要手段。本文在评述了目前利用扫描电极测量金属表面电位分布的各种方法基础上,建立了新的实验系统。文中阐述了本方法的电化学理论基础,提出了获得外径低达数微米且具有良好电化学性能的 Ag/igCl参比电极,设计制造了微参比电极在样品表面附近自动扫描的机械装置,研制了具有高输入阻抗,强抗干扰能力的电位分布测定仪器,还介绍了测量电流密度分布等方法。本实验系统具有较高的测量精度,整套装置简易可行,能满足测量实际腐蚀体系的要求。     

尺寸效应对微电极腐蚀行为的影响

采用动电位极化、交流阻抗(EIS)和电化学噪声(ECN)等电化学方法研究了304不锈钢微电极的腐蚀行为。实验结果表明：极限扩散电流密度与电极尺寸之间具有非线性关系,随着电极面积的减小,极限扩散电流密度增大,溶液阻抗减小,双电层电容增大,自腐蚀电位负移,腐蚀电流密度增大。电化学噪声谱表明,随着电极面积减小,亚稳态点蚀噪声峰的频度降低,亚稳态点蚀的发生存在一个临界尺寸。     

Q345E钢在3.5%NaCl水溶液中的缝隙腐蚀行为研究

应用矩型缝隙模型研究了Q345E钢在3.5%Na Cl水溶液中的缝隙腐蚀行为。探讨了矩型缝隙内电极电位、Cl-浓度和缝口尺寸对缝隙腐蚀的影响。结果表明,随腐蚀时间延长,缝隙内电极电位逐渐减小,Cl~-浓度逐渐增大;距缝口距离越远,Cl~-浓度越大;缝口尺寸较小时,缝隙内的电极电位更负,Cl~-浓度更大。     

锌皮在一次Zn-Ag_2O电池中的参比性能研究

通过电化学方法在10℃条件下测试了一次Zn-Ag2O电池材料测试过程中使用的锌皮参比电极的性能。在KOH溶液中浸泡10 min后,锌电极能够提供稳定的(-1555±5)mV左右的参比电极电位,极化曲线的拟合结果显示随时间的延长腐蚀电流没有发生显著的变化,保持在2×10-5A/cm2数量级,电化学阻抗谱图各阶段容抗弧实部ZRe和虚部ZIm值变化均不大。测试结果表明,锌电极在7 mol/L的KOH溶液中长时间的腐蚀反应速率变化不大,能够提供稳定的参比电极电位,可以作为Zn-Ag2O电池材料测试及某些碱性电解质中电化学测试的参比电极使用。     

全固态Ag/AgCl参比电极电位稳定性的影响因素

采用热浸涂-电化学还原工艺制备得到全固态Ag/AgCl参比电极,并研究了Cl-浓度、温度、光照、水流流速及pH值对电极的影响。结果表明,制备的全固态Ag/AgCl参比电极Nernst响应和温度响应特性较好,温度系数较小;当溶液中有溶解氧存在时,光照会使电极表面生成Ag2O,使电极电位发生漂移;随海水流动速度的升高,Ag/AgCl参比电极的电极电位呈下降趋势,而pH值的变化对电极电位基本没有影响。     

Cl-浓度对X70管线钢缝隙腐蚀的影响

应用楔型缝隙模型研究了腐蚀介质中Cl~-浓度对X70管线钢缝隙腐蚀的影响规律.实验结果表明:在自然腐蚀状态下,当缝口宽度为0.15 mm以及实验周期为120h时,随着缝外腐蚀介质中Cl~-浓度(c~m_(Cl~-))的提高,从缝口到缝底缝内溶液中的Cl~-浓度(c~c_(Cl-))逐渐增加,pH值逐渐降低,试样的电极电位也逐渐降低,表明随着腐蚀介质中c~m_(Cl~-)的增加,X70管线钢的缝隙腐蚀倾向逐渐增强.     

Cl~-对高氮不锈钢在0.5mol/L NaOH溶液中腐蚀行为的影响

利用动电位极化曲线、电化学阻抗谱和恒电位极化电流响应曲线对一种高氮不锈钢在含不同浓度Cl~-的0.5mol/L NaOH溶液中的腐蚀行为进行了研究。结果表明:高氮不锈钢在含Cl~-的0.5mol/L NaOH中具有良好的耐蚀性,极化曲线表现出阳极钝化特征,Cl~-浓度对点蚀电位无显著影响,钝化电流密度随Cl~-浓度的增加而增大;当Cl~-浓度增加到1.00mol/L时,高氮不锈钢表面生成的钝化膜呈n型半导体,仍具有良好的保护性,钝化膜的载流子密度随着Cl~-浓度的增加而增大。     

Galvanic corrosion behaviour of iron coupled to aluminium in NaCl solution by scanning eectrochemical microscopy

Scanning electrochemical microscopy (SECM) was used to sense the concentration of ions in 0.1M NaCl aqueous solution at the iron-aluminium couple. The SECM measured the concentration of ions relevant to the corrosion processes. The electrochemical behaviour of galvanic Fe/Al coupling was investigated as a function of time using SECM microelectrode tip. SECM amperometric line scan curves were obtained over the Fe/Al at a constant distance. In the first case the chemical species participating in the corrosion reactions at the sample are detected at the SECM-tip by applying appropriate potential values to the microelectrode. The release of Al³⁺ into the solution from local anodic surface, as well as the consumption of dissolved oxygen at the corresponding cathodic surface was successfully monitored. The results revealed that the galvanic couple where Fe/Al is close to each other will show lower corrosion rate due to the formation of corrosion products on the metal surface with further increase in exposure times.     

Crevice corrosion monitoring of titanium and its alloys using microelectrodes

Crevice corrosion of titanium and its alloys in 10% sodium chloride was investigated at 100°C with the aid of microelectrodes. Potential, pH and chloride ion concentration inside the crevice were monitored using an Ag/AgCl electrode, a tungsten microelectrode and a Ag/AgCl chloride ion selective microelectrode, respectively. The pH and Cl^? concentrations within the crevice were calculated from the standard potential‐pH and potential‐log[Cl^?] calibration curves. The effect of Mo on the crevice corrosion of titanium was also studied. The passivation behavior on the titanium and Ti‐15%Mo alloy was studied using electrochemical impedance studies. There was no apparent change in pH and Cl^? ion activity inside the crevice for the alloy at 100°C, whereas a marginal decrease in pH and increase in Cl^? ion concentration were observed for pure titanium. Thus pure titanium is susceptible to crevice corrosion in hot 10% NaCl solutions at 100°C. The chloride ion activity was found to be reduced for the alloy so that the pH inside the crevice increased. The corrosion reaction resistance (R_t) was found to increase with the addition of Mo as an alloying element. It also increases with externally applied anodic potential. Hence, Mo is an effective alloying element, which enhances the crevice corrosion resistance of titanium.     

Scanning Electrochemical Microscopy for the Investigation of Galvanic Corrosion of Iron with Zinc in 0.1 M NaCl Solution

Scanning electrochemical microscopy was used to monitor microscopic aspects of the electrochemical processes at the iron-zinc couple immersed in 0.1 M NaCl aqueous solution. The SECM measured the concentration of chemical species relevant to the corrosion processes. The electrochemical behavior of galvanic Fe/Zn coupling was investigated as a function of time using SECM microelectrode both as Fe/Zn joined together as well as away from each other. SECM amperometric line scan curves were obtained over the Fe/Zn at a constant distance. In the first case, the chemical species participating in the corrosion reactions at the sample are detected at the SECM tip by applying appropriate potential values to the microelectrode. The release of Zn²⁺ ionic species into the solution phase from local anodic sites, as well as the consumption of dissolved oxygen at the corresponding cathodic locations, was successfully monitored. The results revealed that the galvanic couple where Fe/Zn is close to each other will show higher corrosion rate of zinc than that of galvanic couple away from each other. The Fe/Zn couple away from each other showed a decrease in current values with time. This is due to the formation of oxide layer of Zn over the Fe followed by the protection of the corrosion products with further exposure times.     

钢筋在混凝土模拟孔隙液中腐蚀电化学行为

采用动电位极化曲线法研究了钢筋在混凝土模拟孔隙液中腐蚀电化学行为.结果表明:随着Cl-离子浓度升高,PH值下降,腐蚀电流(Icorr)增大,破裂电位(En)降低:致使钢筋表面钝化膜破裂的临界Cl-离子浓度与孔隙液的pH值之间存在对数关系.提出了Cl-和OH-在钝化膜局部区域上的竞争吸附模型,并解释了实验结果.     

无氧铜表面特定清洗液的腐蚀机制及溶液特性

目的通过无氧铜特定清洗液的溶液配方实验、腐蚀机制测定以及清洗液浓度表征,为实现无氧铜稳定清洗提出技术方案。方法采用铬酐和浓硫酸互配进行溶液配方实验并采用扫描电镜形貌和腐蚀速率对结果进行对比分析;采用电化学循环伏安法研究了铜浓度对腐蚀速率的影响;采用EDTA络合滴定法测定铜浓度和氧化还原滴定法测定六价铬浓度进行了分析。结果 60~80 g/L铬酐+40~60 m L/L硫酸+余量水的溶液清洗可以获得均一稳定的表面,其中铬酐发挥着氧化剂的作用,硫酸发挥着调整酸度的作用;适当的铜离子浓度对化学反应有促进作用,随着铜离子质量浓度增大至5 g/L以上,腐蚀动力减缓,腐蚀速率减慢。结论提出了无氧铜稳定清洗的合适浓度,得出了腐蚀机制及溶液特性的具体结果。     

Corrosion of cold-deformed brass in acid sulphate solution

The corrosion behaviour and the dezincification process of cold-deformed CuZn-42 brass were tested in an acid sulphate solution at pH-value 2 with additional chloride and copper(II) ions by use of the linear polarization method.The measured corrosion potential and densities of corrosion currents were observed as characteristics of the dezincification process and the corrosion resistance of tested samples of cold-deformed CuZn-42 brass. The results obtained have shown that pH-value 2 of the tested solutions and increased concentrations of copper(II) ions result in increased values of densities of corrosion currents of the tested brass samples, as a result of selective zinc dissolution and the individual dissolution of zinc and copper including the process of anodic oxidation. The tested concentrations of chloride ions in certain conditions have an inhibiting effect, whereas in the other conditions they act as distinctive activators of brass corrosion. The lowest values of corrosion currents are present in the brass samples with the highest deformation degree at 80%. The process of dezincification and anode dissolution of cold deformed brass samples were developed in the whole range of tested potentials.     

混凝土结构中钢筋腐蚀电位与腐蚀电流在液面附近的分布

将含钢筋的混凝土试样部分浸泡在3.5% NaCl溶液中,测量溶液以及溶液上方混凝土中钢筋试样的腐蚀电位、宏电池腐蚀电流,通过极化电阻R_p值计算钢筋的腐蚀电流密度。结果表明位于溶液中混凝土内钢筋试样的腐蚀电流密度随着其在溶液中深度的增加而降低。位于溶液上方混凝土中钢筋试样的腐蚀电流密度随着其所处的位置升高而降低,说明溶液中混凝土中钢筋的腐蚀与氧含量密切相关。溶液上方的混凝土中钢筋的腐蚀与混凝土湿度密切相关。     

不锈钢及镍基合金在含溴醋酸中的点蚀行为

采用动电位扫描对254 SMO,Nickel 200和Hastelloy C-276三种材料在含溴醋酸中的点蚀行为进行了研究,并采用SEM观察点蚀形貌,实验结果表明,这三种材料耐点蚀的顺序从低到高为：Nickel200,254SMO和Hastelloy C-276。对于材料254 SMO,在含有少量醋酸的情况下,［Br∧-］的对数与其点蚀电位和保护电位呈线性关系,而且它们的斜率相等,采用XPS对极化后的试样进行表面分析,发现MoO2,Cr2O3对材料起到了了保护作用,阻止了点蚀的发生。     

Corrosion behavior of iron thin film in deaerated phosphate solutions by an electrochemical quartz crystal microbalance

The corrosion rates of iron thin film in deaerated phosphate solutions were measured by an electrochemical quartz crystal microbalance as a function of solution pH or phosphorus concentration in solutions. The dependences of corrosion rate and corrosion potential on solution pH and phosphorus concentration have suggested that the corrosion mechanism changes in the vicinity of pH 5 and H₂PO₄⁻ contributes to both anodic dissolution of iron and hydrogen evolution. The corrosion mechanism which contains iron-phosphate-hydroxide complex ion as an adsorbed intermediate was proposed to explain the experimental results.     

Influence of temperature and chloride ion concentration on the corrosion behaviour of Mg–4Al–3Ca–0.5RE alloy

The influence of temperature and chloride ion concentration on the corrosion behaviour of Mg?4Al?3Ca?0.5RE alloys were studied in this paper. Corrosion rates of the alloys were measured by weight loss test and electrochemical measurement. The results revealed that a shorter incubation period to the onset of corrosion, a more negative corrosion potential, and a higher corrosion rate was correlated with a higher temperature in 3% NaCl solution and a higher chloride ion concentration at 30°C. The corrosion behaviour of the alloys was affected by surface film and the corrosion mainly occurred at the breaks or defects in surface films.