电解工艺条件对铝箔腐蚀形貌与比电容的影响

利用扫面电镜(SEM)、数字电桥研究了铝电解电容器用高压电子铝箔在硫酸+盐酸体系中进行电化学腐蚀扩面时,工艺条件对铝箔腐蚀形貌与比电容的影响规律:电解腐蚀时间对铝箔腐蚀后形貌与比电容影响较大,发孔时间延长、扩孔时间缩短,隧道孔密度增加、孔直径减小;发孔电流密度对铝箔腐蚀形貌与比电容影响较小,只要高于点蚀电流密度,小电流长时间发孔与大电流短时间发孔都可以在铝箔表面形成足够密度的蚀孔结构;电解液温度对铝箔腐蚀形貌和比电容影响较大,随着发孔液温度的提高,蚀孔密度增加、蚀孔孔径减小,隧道孔长度减小.     

铝箔表面化学镀锌对其在HCl-H 2 SO 4体系中电蚀性能的影响

将高压铝电解电容器用电子铝箔在含Zn2＋的5.0%NaOH溶液中实施化学镀锌处理,然后在HCl＋H2SO4电解液中进行直流电解扩面腐蚀得到腐蚀箔;采用极化曲线研究化学镀锌处理对扩面腐蚀时铝箔点蚀电流、点蚀电位的影响,利用电化学交流阻抗（EIS）研究化学镀锌处理对铝箔电解腐蚀时电化学特征的影响;使用扫描电镜（SEM）观察化学镀锌处理对腐蚀箔表面和横截面形貌的影响;测试100 V形成电压下腐蚀箔的比电容。结果表明：铝箔表面化学镀锌形成的Zn-Al微电偶有助于电蚀时降低点蚀电极反应的阻力,提高点蚀电流密度,增加铝箔表面蚀孔密度和蚀孔分布的均匀性;随着碱液中Zn2＋浓度的提高,腐蚀箔的比电容逐渐增加。     

氢对纯镍钝化膜的影响

研究了氢对纯镍阳极极化和钝化膜形成及耐蚀性能的影响。结果表明：预充氢会降低纯镍的自腐蚀电位,使其出现明显的活化区和临界钝化电流,缩短钝化区域;提高钝化电流密度和延长钝化膜的形成时间。固溶氢降低钝化膜的稳定性,增大膜的自活化能力;并导致钝化膜出现明显的孔蚀,膜的孔蚀电位随固溶氢含量的增加而降低。     

磁场对车轴钢在含氯离子碳酸氢钠溶液中阳极过程的影响

采用电化学测试结合表面形貌观察研究了0.4T磁场对车轴钢在碳酸氢钠溶液及含氯离子碳酸氢钠溶液中阳极过程的影响。极化曲线测试结果表明:0.4T磁场显著增加预钝化区的电流密度;对碳酸氢钠溶液中的过钝化区无显著影响,但增加含氯离子碳酸氢钠溶液中过钝化区的阳极电流;试样在施加磁场的溶液中经极化曲线测试后的表面点蚀情况比无磁场条件下的严重。恒电位极化测试结果表明:在极化曲线预钝化区内,磁场会使电流衰减速率变缓慢;在钝化区内,磁场会使初始电流密度增大、点蚀数量增多;在过钝化区内,磁场显著增大电流密度并导致更多和更大的点蚀。     

316L奥氏体不锈钢在不同电位下的点蚀和再钝化行为研究

目的研究外加电位对316L奥氏体不锈钢点蚀和再钝化行为的影响。方法采用循环极化、恒电位极化,电化学阻抗谱(EIS)等多种电化学测试方法,研究了系列电位与混合电位对316L奥氏体不锈钢点蚀敏感性的影响,并采用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)观察分析钝化膜点蚀形貌和元素含量。结果在60℃的饱和CO_2的10 g/L NaCl溶液中,316L奥氏体不锈钢的钝化区间为-0.394～0.168 V,但电位在-0.100～0.168V之间,即亚稳态点蚀区时,电流出现一定的波动。在钝化区极化时,316L奥氏体不锈钢的稳态电流密度非常低,随外加电位的升高而略有增加,极化后试样表面无点蚀;在亚稳态点蚀区,极化的电流密度较高,极化后,试样表面出现明显的点蚀坑;混合区极化时,电位从0.1 V转换到-0.1 V时,电流密度急剧下降,并稳定在一个较低的电流值。XPS结果表明,在钝化区电位极化后,Cr、Mo元素含量有所升高,而Fe元素发生了选择性溶解。结论 Cr、Mo元素是耐蚀性元素,其氧化物或氢氧化物的存在可促进钝化膜的局部修复,因此电位转换到低电位后,试样表面发生再钝化现象,钝化膜的稳定性增强,材料的耐蚀能力提高。     

304不锈钢稳态点蚀生长动力学及孔内环境测定

利用电感耦合等离子体发射光谱法(ICP-OES)及三维显微镜测定了304奥氏体不锈钢在不同极化电位下生成的单个三维稳态蚀孔内部的腐蚀产物浓度,同时,基于扩散控制理论,根据菲克第一定律计算了蚀孔内部腐蚀产物浓度的理论值,并观测和计算了蚀孔形貌及孔内点蚀电流密度,分析了蚀孔生长速度与孔内腐蚀产物浓度、极化电位、蚀孔几何形貌间的关系.结果 表明:ICP-OES测得的304不锈钢单个蚀孔内部的腐蚀产物浓度随蚀孔体积及极化电位增加而降低,孔内点蚀电流密度及蚀孔开放程度均随极化电位的升高而增大,基于扩散控制理论计算得到的孔内腐蚀产物浓度理论值显著高于ICP-OES实测值,高极化电位下304不锈钢上生成的蚀孔具有更大的孔内点蚀电流密度及更低的孔内腐蚀产物浓度,说明在阳极极化下,304不锈钢上生成的三维稳态蚀孔的生长速度并不完全受控于腐蚀产物的扩散过程,受电化学活化控制的程度更大.     

磁场对铁在含氯离子的碳酸钠溶液中阳极过程的影响

通过动电位极化和恒电位极化的方法,研究了磁场对铁在含氯离子的Na_2CO_3溶液中阳极过程的影响。结果表明:磁场会降低极化曲线钝化区内的电流密度;较低扫描速率下磁场使极化曲线过钝化区内的电流密度增大,较高扫描速率下磁场使过钝化区高电位区间内的电流密度降低;在极化曲线钝化区较低电位区间内,磁场会使电流密度降低;在钝化区较高电位区间内,磁场对电流密度的影响不明显;磁场对过钝化区阳极反应的加速效应随极化电位的升高而减弱。     

电流对高纯铝箔交流电侵蚀的影响

研究了在ＨＣｌ 溶液中５０ Ｈｚ 交流电侵蚀下电流密度对电解电容器用高纯铝箔的腐蚀行为的影响。结果表明， 侵蚀初期的真实电流密度决定铝箔蚀孔的尺寸和表面膜， 大电流在铝箔表面产生厚膜，阻碍交流电侵蚀的阴、阳极反应过程和蚀孔深入。随着电流密度减小， 试样的蚀孔孔径增大， 在＜ ０ ．２Ａ／ｃｍ ２ 电流下的蚀孔比其它大电流下的蚀孔孔径大４ 倍左右。先用＜ ０ ．２ Ａ／ｃｍ２ 的小电流侵蚀， 再用０ ．２ ～０ ．５ Ａ／ｃｍ２ 大电流侵蚀组合， 铝箔电容量随电量的增加直线上升。用５０ Ｈｚ 交流电可以使铝箔获得良好的起始发孔， 得到具有较大孔径和多向堆垒型海绵层蚀孔的大容量电解电容器用铝箔     

TiNi及Co合金生物医用材料的腐蚀行为及血液相容性

采用线性极化技术测量了生物医用材料TiNi形状记忆合金, CoCrNiMo和CoCrNiW的腐蚀速率, 并用动态电位扫描法考察了其阳极极化行为. 结果表明, 3种合金钝化电位区宽, 维钝电流密度小, 显示出优异的耐全面腐蚀性能. 电位扫描曲线滞后环面积及腐蚀后扫描电镜观察显示, 两种钴合金具有良好的耐孔蚀性能, 而TiNi的孔蚀倾向较大, 这是因为在TiNi合金表面夹杂的Ti2Ni易受活性阴离子的浸蚀, 而钴合金中的Co, Cr, Mo和W均易在表面形成钝性氧化膜, 抑制孔蚀的发生. 接触角、动态凝血时间和溶血率的测定表明TiNi具有更优的血液相容性, 这可能与其表面的TiO2膜具有较小的表面张力有关.     

H2S水溶液中的腐蚀与缓蚀作用机理的研究Ⅳ．碱性硫化物溶液中Cl-对碳钢钝化行为的影响

利用交流阻抗和动电位极化技术,在碱性硫化物溶液中,分别研究了阳极极化电位下 对 低碳钢钝化过程阻抗行为的影响,钝化膜临界孔蚀电位 与 浓度的关系以及临界 浓度随 温度的变化．结果表明,在除氧的碱性硫化物溶液中,阳极极化的初期阻抗具有两个时间常数,随极化电位的升高,钝化膜逐步趋于完整;在点蚀的形成过程中,容抗弧半径逐渐变小,当极化电位为-600mV时容抗弧半径大幅度下降,并出现低频实部电感性收缩现象;在点蚀形成后的发展阶段,容抗弧半径继续减小,阻抗谱出现两个时间常数的双容抗弧．极化研究结果表明,不同温度下,随介质Cl-浓度增加,电极表面的钝化倾向降低,临界孔蚀电位随Cl-浓度增加而线性正移．     

Elektrolytische Tunnelätzung von Aluminiumfolie

Electrolytic tunnel etching of aluminium foil The most effective method of etching aluminum foil for high voltage electrolytic capacitors is the electrolytic tunnel etching with direct current in an aqueous solution of chloride salts. Surprisingly the classical electrochemical method for determining the potentiostatic current-time curves of annealed high purity aluminum foil delivers a pure tunnel etching in a narrow range around the pitting potential. The potentiostatic current-time curves show the dynamic of the very fast and on an already etched aluminum foil not repeatable process of forming the tunnels (tunnel diameter ca. 0.2 μm; tunnel length 10–100 μm) and immediate after tunnel formation the about 1000 times slower and controllable process of widening these tunnels in the region of passivation current density.     

硫脲对非调质钢在HCl酸洗溶液中的缓蚀作用

目的 研究硫脲(TU)对非调质钢在HCl溶液中的缓蚀作用.方法 通过动电位极化曲线、电化学阻抗谱研究硫脲对非调质钢在HCl溶液中的缓蚀效应,采用KH-7700型三维视频显微镜观察非调质钢的腐蚀形貌.结果 非调质钢在不合缓蚀剂的HCl溶液中的自腐蚀电位(Ecorr)为-0.566V,自腐蚀电流密度(Jcorr)为12.57 mA/cm2.随着HCl溶液中硫脲浓度的增加,非调质钢的自腐蚀电流密度(Jcorr)逐渐减小,反应电阻(Rct)逐渐增大,界面双电层电容Cdl降低,缓蚀效率逐渐增加,阴极极化曲线几乎重合,而阳极极化曲线逐渐正移.当HCl溶液中加入5g/L硫脲时,缓蚀效率达91.17％,效果好于市售酸洗缓蚀剂AS-30,能够有效消除非调质钢在HCl酸洗液中的腐蚀麻点.结论 硫脲对非调质钢在HCl溶液中具有明显的缓蚀效应,能够有效消除非调质钢酸洗过程中的腐蚀麻点.     

Dissolution, passivity and its breakdown on iron whisker crystals

The anodic polarization behaviour of iron whisker crystals was investigated in a neutral solution with or without the presence of chloride ion, with special attention to the role played by surface defects in the dissolution, the passivation and the pitting of iron. The grown whisker used was substantially dislocation-free and the defect density was varied by twisting of whisker. With increase in the angle of twisting, the anodic dissolution current increased in a chloride-free solution, whereas it decreased in a chloride-containing solution. The defect density in the substrate had no remarkable effect on passivation but the thickness of the passive film was slightly increased on twisted whiskers. The anodic polarization curve of a grown whisker in a chloride-containing solution did not exhibit a distinct pitting potential. By twisting of whisker, however, a current rise due to pitting appeared on the polarization curve and the apparent pitting potential shifted in the negative direction with increasing angle of twisting. Potentiostatic polarization experiments in a chloride-containing solution showed the emergence of random current pulses due to the breakdown of passive film and to repassivation. It is highly probable that the breakdown of the passive film occurs at the physical or chemical inhomogeneities in the passive film not associated with dislocation termini but that pitting occurs only when the breakdown occurs at emergent dislocation sites.     

Potentiodynamic behaviour of the nickel electrode in acid media

The electrochemical behaviour of nickel has been investigated in H₂SO₄ and HCl solutions of various concentrations by means of the potentiodynamic method. In very dilute solutions, the low anodic current is controlled by the presence of pre-existing film. At higher concentrations the film is removed and dissolution occurs. In H₂SO₄ solutions, pseudopassivity, primary passivity, transpassivity and secondary passivity are observed prior to oxygen evolution. In all these regions, the rate of dissolution increases with acid concentration. In HCl solutions, the anodic polarization curves exhibit a current peak followed by a passivation region; the latter may not involve complete passivity. In the active region, the uniform dissolution is controlled by diffusion processes. In the passive region, local attack in the form of pitting occurs. In both acid solutions, the cathodic and anodic polarization curves satisfy Tafel's relation.     

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。     

Cu和Al对铁素体不锈钢在氯化物介质中腐蚀行为的影响

通过测定合金在不同ｐＨ值的含１ｍｏｌ／Ｌ Ｃｌ＾－的水溶液中的阳极极化曲线，绘制了四种铁素体不锈钢的实验电位－ｐＨ图，从而研究了Ｃｕ及Ａｌ元素对不锈钢耐蚀性能的影响。在１８Ｃｒ－２Ｍｏ铁素体不锈钢中添加０．５５％的Ｃｕ使点蚀击穿电位Ｅｂ正移，对局部腐蚀的萌生起阻滞作用。     

Ni_3Al(B)系金属间化合物在LiCl-KCl熔盐中的腐蚀电化学行为

研究了Ｎｉ３Ａｌ（Ｂ）系金属间化合物在４５００Ｃ纯的和含有“杂质”的ＬｉＣｌ－ＫＣｌ熔盐中的阳极极化曲线。发现在纯盐中阳极不出现Ｆｌａｄｅ电位,不发生电化学钝化。在含有“杂质”的熔盐中,所研究的金属间化合物都出现电化学钝化,阳极电流密度降低。Ｌｉ２ＣＯ３是合金熔盐腐蚀有效的缓蚀剂。在分别含有“杂质”ＭｇＯ、ＺｎＯ、ＭｎＯ２金属氧化物的熔盐中,金属间化合物的阳极电流密度都增高,并依据金属氧化物的溶解度积,有时会使合金的阳极极化曲线出现扩散控制或电化学钝化过程。讨论了在ＬｉＣｌ－ＫＣｌ熔盐腐蚀电化学中的作用,指出三条途径形成的氧化物及其行为。     

Growth and passivation of aluminum etch tunnels at on-off controlling direct current in 6 wt. % HCI solution

Growth and passivation of tunnels within Al foil by on-off controlling DC etching in 6 wt.% HC1 solution has been investigated.It was found that,in a given etchant solution at a special temperature,the longest tunnel length was only a function of the turn-on interval of DC.The potential of AI foil broke at on-off controlling DC by the result from anode polarization curves and potential-time (E-t) responding curves.When DC was switched on,the potential increased abruptly over pitting potential,leading to nucleation of pits at the surface and the growth of tunnels at special length.When DC was switched off,the potential decreased rapidly to a passive value,leading to stoppage of nucleation and death of tunnels.By this way,the longest tunnel length can be controlled and a non-piercing layer can be obtained.Hence,etching of Al foil at this current is beneficial for maintaining a good mechanical strength.     

Growth and passivation of aluminum etch tunnels at on-off controlling direct current in 6 wt.% HCl solution

Growth and passivation of tunnels within Al foil by on-off controlling DC etching in 6 wt.% HCI solution has been investigated. It was found that, in a given etchant solution at a special temperature, the longest tunnel length was only a function of the turn-on interval of DC. The potential of Al foil broke at on-off controlling DC by the result from anode polarization curves and potential-time （E-t） responding curves. When DC was switched on, the potential increased abruptly over pitting potential, leading to nucleation of pits at the surface and the growth of tunnels at special length. When DC was switched off, the potential decreased rapidly to a passive value, leading to stoppage of nucleation and death of tunnels. By this way, the longest tunnel length can be controlled and a non-piercing layer can be obtained. Hence, etching of Al foil at this current is beneficial for maintaining a good mechanical strength.     

基于阳极极化曲线的预测镁合金微弧氧化起弧特性的新方法

提出了一种以镁合阳极极化曲线来判断微弧氧化起弧难易的新方法。在不同的电解液中,测试了镁合金的阳极极化曲线及微弧氧化的起弧特性。结果表明,起弧电压首先与其在对应电解液中进行阳极极化时形成的钝化膜的稳定性有关:膜层越稳定,即阳极极化曲线上钝化区宽度越宽,则在相应的电解液中微弧氧化起弧电压越低;当钝化区间宽度相近时,则在钝化区间后期极化电流越小,起弧电压越低。