Current levelling behaviour under pulse current electroplating conditions: The role of reaction pseudocapacitance

Despite growing interest in pulse current electroplating, published theories have not evolved beyond treatments of simple, single-step reaction kinetics. This omission of multiple-step kinetics and associated reaction pseudocapacitance is responsible for the inability to interpret mechanistically several key pulse current electrodeposition process characteristics.A complex kinetics charge transfer model is developed to describe the enhanced geometric control of deposit thickness achievable with judiciously chosen pulse current control conditions. This semiquantitative analysis demonstrates that deposit thickness levelling is primarily the result of the strong potential dependence of the reaction pseudocapacitance, together with proper choices of pulse current control variables. For any system of interest, a well defined on-time current,I _A, and on-time and off-time periods,t _A andt _B, are optimum for minimizing relative deposit thickness variation.     

Zn-Fe合金电镀工艺的研究

探讨了氯化物体系Zn Fe合金电镀液中各组分及其他工艺参数对镀层中铁含量的影响。在最佳Zn Fe合金电镀工艺条件下 ,得到了含铁量为 0 41 %的Zn Fe合金镀层 ,经银白色钝化后的该种合金镀层的抗蚀能力约为同厚度纯锌镀层的 2～ 3倍。研究同时表明 ,Zn Fe合金镀液具有良好的分散能力、覆盖能力和整平能力 ,电镀电流效率高 ,镀层性能优良     

Surface profilometric study of the kinetics of the intercalation of graphite

The kinetics of the intercalation of graphite was investigated by measuring the c-face surface profiles during the intercalation of Br₂ into highly-oriented pyrolytic graphite cylindrical discs at room temperature. A sharp intercalate front was observed to advance while the surface profile evolved from a bucket-shape to a V-shape, as predicted by the model of interface-controlled intercalation proposed by the authors [11]. The average magnitude of the steady velocity of the front was ~ 15 Å/see; the initial period was marked by a larger velocity attributed to an edge effect. The same behavior was observed during ICI intercalation at room temperature. During desorption, inverted surface profiles were obtained, indicating that desorption may be the reverse of intercalation. In the case of HNO₃ intercalation at room temperature, bowl-shaped surface profiles were observed. Preliminary profile measurements were made during ICI intercalation at 50°C, at which the intercalate layers are known to be disordered.     

Bitrex: A new levelling agent for copper

We investigate the effects of denatonium benzoate (Bitrex) on the electrodeposition of copper films from a boric acid bath using scanning electron microscopy, cyclic voltammetry, electrochemical quartz microbalance (EQCM) measurements and corrosion studies. In the absence of Bitrex, pure copper films grown by this method are optically black owing to the appearance of complex surface nanostructures. The addition of Bitrex acts as a levelling agent preventing the formation of these nanostructures even for concentrations as low as 0.02 mM producing a lustrous film with low surface roughness. Bitrex is also found to improve the corrosion resistance by up to a factor of 20 and increase the current efficiency by over a factor of two. Bitrex is hypothesised to act directly on the cathode, partially inhibiting the growth or lowering the deposition current.     

绿色电镀技术的探讨

本文提出绿色电镀的内涵，探讨如何从电镀过程的生命周期来贯穿绿色电镀技术，针对电镀行业在减少污染、合理利用资源、节约能源以及在应用环境无害化等方面的技术要求，分析了电镀行业清洁生产的潜力，提出了电镀工业实现清洁生产的途径。采用绿色电镀技术和清洁生产技术能最大程度的减少和消除传统电镀给环境带来的污染和危害。     

电镀集中区电镀废水的处理

废水处理是电镀集中区建设成功的关键.提出了搞好电镀集中区中电镀废水处理的一些前提与方法:首先要按清洁生产的要求对入驻集中区的企业进行审核,同时要认真剖析集中区内电镀废水的特点,运用循环经济的理念对不同电镀废水进行分类收集,采用最佳的废水处理技术,并根据"集散控制模式"进行处理,以达到回用废水及回收废水中有价值的重金属的理想效果.对各种先进的处理技术(包括化学法、膜分离技术、螯合沉淀法、HR型除铬机、生化法和高压脉冲电凝加硅藻土整合技术)进行了对比.推荐采用国外某公司的重金属捕捉剂.     

电镀中的“标准化”

总结了电镀生产中操作标准化和管理标准化方面的经验,介绍了一些标准化的操作行为和操作手法(包括带电入槽、抖动工件和清洗)、列举了一些员工培训及工艺控制方面实施标准化的例子。     

镁合金表面电镀锌工艺的应用研究

镁合金碱性锌酸盐镀锌工艺所得的锌镀层光亮,耐蚀性高,碱性锌酸盐镀锌层厚度超过10μm时,钝化后呈均匀五彩色,中性盐雾试验超过96 h.焦磷酸盐镀锌工艺整平能力好,镀层结晶细致,以焦磷酸盐镀锌层作为底层,再碱性锌酸盐加厚镀锌,能有效改善锌镀层的光泽度和耐蚀性,同时降低成本.     

An electrochemical mass transport sensor to study agitation in electroplating processes

A sensor based on limiting current density characteristics of a wire tip electrode has been shown to be capable of measuring local variations of agitation and its effect on coating thickness variations during electrodeposition. The effectiveness of agitation is expressed as an enhancement factor.     

电引起的电镀故障

介绍了4例因电路或电源出了问题而引起的电镀故障。     

综合电镀废水处理技术的实验研究

以深圳某大型电镀工业园产生的综合电镀废水为研究对象,对其处理方法进行了探索,确定了酸化-氧化破络反应及氢氧化物和硫化物共沉淀的处理方法;通过实验选择漂水为最佳破络剂,最佳破络操作参数为漂水用量1.2mL/L,反应pH为2.3,反应时间2.0h,在此基础上调节pH并加入硫化钠即可实现电镀废水的达标排放,克服了传统电镀废水处理工艺的不足。     

锌铁磷合金电镀的发展现状

锌铁磷合金镀层是在Ｚｎ－Ｆｅ、Ｚｎ－Ｐ或Ｆｅ－Ｐ合金的基础上发展起来的一种钢铁表面的防护与装饰性镀层。它具有优良的耐蚀、涂装、焊接及加工等性能,成本低,应用范围广。本文回顾了国内外锌铁磷合金电镀的研究现状,总结了其分类、镀层性能、沉积机理及添加剂组成,并提出了其今后的研究方向。     

恒电流密度滚镀锌试验研究

设计了一种适合滚镀的电流密度传感与测试装置,采用全数字控制的高频开关电源,在恒电流密度下进行了滚镀锌闭环控制试验研究。结果表明:在相同工件、相同时间的条件下,恒电流密度闭环控制模式比恒电压模式节能10%,且膜厚均值较大;随着电镀时间延长,恒电流密度闭环控制模式下的镀层厚度变化趋于平缓,但镀层厚度分散程度较恒电压控制模式时大。     

MBR工艺处理工业园区电镀废水的中试应用研究

针对工业园区电镀废水处理中生化指标达标难的问题,采用新型聚四氟乙烯(PTFE)膜组件构建膜生物反应器(MBR),通过现场试验研究了MBR工艺处理电镀废水的实际效果。结果表明,通过合理的维护管理,MBR膜通量能稳定维持在16.67L/(m2·h)左右,对COD的去除率可达到50%以上,出水COD质量浓度稳定在80mg/L以下,但对氨氮的去除效果受水力停留时间(HRT)、温度、系统负荷等因素的影响较大。与传统的生物接触氧化工艺相比,基于新型膜材料的MBR工艺可以大大提高污泥量,避免结垢和出水跑泥等问题,提高了处理效果。从投资运行费用来看,采用MBR工艺的总投资费用高于普通生化处理工艺,运行费用约为2元/t。     

电镀废水零排放工程实例

根据电镀废水水质的特点,对含氰废水、含油废水、含铬废水、含镍废水和含铜废水进行分类前处理后,与混排废水混合进行混凝沉降-MBR(膜生物反应器)法预处理,采用超滤和反渗透装置对废水作进一步处理实现回用,反渗透浓水则采用电渗析-MVR(机械式蒸汽再压缩)工艺实现脱盐后再次进入反渗透装置处理回用.工程实践表明,该系统的出水不...     

Application of elimination voltammetry in the study of electroplating processes on the graphite electrode

The electrode reaction mechanism of electrolytical coating by nickel on paraffin impregnated graphite electrode (PIGE) was investigated by cyclic voltammetry (CV) and elimination voltammetry with linear scan (EVLS). The EVLS, a relatively new method of processing electrochemical signals obtained by voltammetry, is able to eliminate some individual chosen currents from total voltammetric currents measured at different scan rates. During the electrodeposition of metals on the graphite electrode, hydrogen evolved from aqueous acidic solutions interferes with the plating process. The elimination of kinetic current arising due to hydrogen evolution enables one to study other processes proceeding at the electrode. Cyclic voltammograms for metal coating deposition/dissolution on the graphite electrode were measured at three scan rates (12.5, 25 and 50 mV/s) and the EVLS functions were calculated for one or two eliminated currents. The results indicate the occurrence of surface reactions with the adsorption of intermediates on graphite. The application of EVLS provides deeper insight into the mechanism of electrode reaction during metal deposition.     

某电镀厂废水重金属去除工艺对比研究

对比研究了中和沉淀法、硫化物沉淀法、Fenton-沉淀法、常温铁氧体法对电镀废水中Cu、Cr和Ni的去除效果.结果表明,铁氧体-硫化物沉淀法联合处理效果最好,当FeCl<,3>和FeSO<,4>投加质量浓度分别为1 890、973mg/L,调节pH至10.3,再加入Na<,2>S至其质量浓度为300 mg/L时,Cu、...     

超声波电镀的研究进展

阐述了超声波的工作原理,介绍了超声波在电镀前以及单金属电镀和合金电镀方面的研究应用。超声波电镀不但可以改善镀层与基体的结合力,还能细化晶粒,改善镀层表面的粗糙度,扩大电流密度,提高电流效率,得到性能更佳的镀层,有很好的应用前景。     

微电解法在电镀混合废水处理中的应用及研究

结合工程实例介绍了微电解法在电镀混合废水处理中的反应机理,说明了其处理工艺的工艺流程及设计参数。实际运行表明,微电解法处理可使电镀混合废水的出水离子浓度ρ（Cu^2＋）〈0．5mg/L,ρ（Ni^2＋）〈1．0mg／L,ρ（Pb^2＋）〈1．0mg/L,达到了排放标准,经济效益和环境效益良好。同时对该工艺进行了进一步研究表明,当进水ρ[Cr（Ⅵ）]〈100mg／L时,可与含Cu^2＋、Ni^2＋、Pb^2＋的电镀混合废水一起处理。