Mechanism of Nanocrystalline Nickel Electrodeposition from Novel Citrate Bath

用电化学阻抗谱研究了在柠檬酸盐镀液中纳米晶镍沉积的电化学行为,确认了Ni(Ⅱ)离子是两步放电,其中吸附物Ni(OH)ads是通过第1步产生。通过分析阻抗谱,除了在高频端出现一个容抗弧,在低频端出现的感抗弧,是由于 Ni(OH)ads在阴极驰豫过程引起的结果。实验过程中观察到的电化学行为和结果能够通过提出的机理得到解释,中间化合物 Ni(OH)ads在电极表面消耗。通过定量分析和模拟,得到了镍沉积过程的阻抗参数。镀液中柠檬酸钠的加入,增加了电荷转移电阻,减小了双电层电容。     

Electrodeposition of Copper from Citrate Alkaline Solution Containing Polyethyleneimine(PEI)

Mechanism of citrate alkaline copper electrodeposition in presence of polyethyleneimine was researched.Tested by SEM,It’s propitious to obtain fine and symmetrical copper film at wider current densities with polyethyleneimine.XRD analysis indicated copper deposits exhibited growth orientation of crystal face(111),which remained with parallel growth.Cyclic voltammograms results indicated that polyethyleneimine adsorbing preferentially at cathode high current density area could make a stronger inhibition on copper electrodeposit.Studied by chronoamperometry,it’s showed that initial stage behavior of copper electrodeposition belonged to diffusion controlled and three-dimensional progressive nucleation.     

A Study into the Electrodeposition Mechanisms of Zinc-Nickel Alloys from an Acid-Sulphate Bath

Zinc-nickel alloys were electrodeposited under galvanostatic conditions from a sulphate based electrolyte. The effect of deposition current density on alloy composition was determined for an electrolyte containing 0.58 mol/l nickel and 0.92 mol/l zinc (as sulphates). At current densities exceeding 0.01 A/dm², a transition from normal deposition to anomalous co-deposition (ie where the less noble metal deposits preferentially) was observed and alloys rich in zinc were obtained. The transition current density was observed to increase with an increase in electrolyte temperature or a decrease in electrolyte pH.

The electrodeposition mechanism for zinc-nickel alloys in the transition regions was studied in detail using potentiodynamic cathodic polarisation techniques. The results were consistent with the suppression of nickel deposition due to the precipitation of zinc hydroxide on the cathode surface. This was supported by pH measurements made in the vicinity of the cathode where a rise in pH was detected as the transition current density was approached and exceeded the critical pH for zinc hydroxide precipitation.     

Electrodeposition of Tin Alloys from Alkaline Stannate Baths

The paper reports on a small development programme designed to concentrate on devising a relatively simple technique for the deposition of copper only in drilled holes of a conventionally produced printed wiring board. It is essential to start with a laminate containing catalysed resin base, producing the printed wiring pattern in the normal manner and plating up holes using autocatalytic electroless copper. Thickness measurements and microsections of electroless copper deposits have been obtained and appear to be encouraging.     

Electrodeposition of Lead from Acetate Electrolyte Containing Additives

The electrodeposition of lead on to steel substrates from acidic acetate electrolyte containing hexadecyl pyridinium bromide (HDPB) and sodium dodecyl sulphate (SDS) has been investigated. In the acetate electrolyte containing a combination of HDPB and SDS, lead of good quality can be deposited. The optimum operating conditions necessary to produce a highly adherent lead deposit have been found to be: pH=5.0, j = 0.33 A dm^?2, T=25°C and time= 10 min. The optimum bath has a throwing power of 19.5% which is relatively high compared with that reported for Pb electrodeposited from sulphamate and fluoroborate baths. X-ray diffraction analysis shows that the Pb deposited from the acetate bath is pure and the surface morphology of the deposit shows that the lead deposited from the optimum bath is compact, non-porous and composed of fine-grains covering the entire surface.     

The Electrodeposition of Iron-Zinc Alloys

Methods are given for depositing iron-zinc alloys of 3 to 90% zinc content from sulphate baths and attention is drawn to the useful properties of these deposits. Under a given set of plating conditions the iron-zinc ratio in the deposit is directly proportional to that in the bath. Lowering either the current density or the pH raises the zinc content of the deposit. Some baths have a levelling action, since bright deposits can be prepared from them on an etched surface. Examples of such baths are: (i) FeSO₄-7H₂O 248, ZnSO₄-7H₂O 8·8, (NHJ₄)₂SO₄ 118, KCl 10, citric acid 0·5 g./l., operated at pH 1·7, 50°G, 200 amps./ft.² and giving a 6% zinc alloy of 560 D.P.N, hardness;

(ii) FeSO₄-7H₂O 174, ZnSO₄-7H₂O 88, (NH₄)₂ SO₄ 118, KCl 10, citric acid 0·5 g., Teepol 0·4 ml./l., operated at pH 1·7, 50°C, 180 amps./ft.² and giving a 60% zinc alloy of 350 D.P.N, hardness.

The throwing power of the baths is comparable with that of a bright nickel bath. Pitting can be overcome by using a wetting agent (Teepol or Lubrol W) and operating at high temperature (80° C.) and low pH (<1·8). Under these conditions the deposits are usually matt and light grey in colour.

Alloys with zinc contents >ca. 30% have electrode potentials in N/10 KCl nearly equal to that of pure zinc. In the C.R.L. beaker test, the alloys with zinc contents between 30 and 90% are, in general, more corrosion resistant than pure zinc. Various applications of these alloys are proposed, including their use as an undercoat for paints and chromium plating and for decorative finishes indoors.

Deposition of iron-zinc alloys from chloride baths is dealt with briefly. A matt, corrosion-resistant alloy of 60% zinc content can be obtained, at pH 1·8, 50° C., and 50 amps./ft.², from a vigorously stirred bath of the following composition:—FeCl₂·4H₂O 177, ZnCl₂ 42, NH₄Cl 100, KCl 15, citric acid 0·5 g./l.

A colorimetrie method for the analysis of zinc in the presence of iron is described.     

水溶液中电沉积制备LaMg2Ni9储氢合金

利用水溶液电沉积法制备La Mg_2Ni_9储氢合金膜,通过测定合金膜的循环伏安曲线(CV)、交流阻抗(EIS)、Tafel极化曲线等研究其电化学性能,采用扫描电镜(SEM)、X射线衍射(XRD)、能谱(EDS)对合金膜表面形貌、结构及组成进行研究。结果表明:电沉积电流密度为40 A/dm~2时,La Mg_2Ni_9合金膜的表面粗糙并伴有裂纹,析氢电流密度为5.37A/dm~2,表观活化自由能△G~≠最低为47.26 k J/mol,证明合金膜良好的析氢性能;吸附值Q达到最大值为0.091μF·cm~(-2),表明合金膜具有较高的储氢性能。     

不锈钢阳极-EDTA-硫酸盐体系锌锰合金电沉积的研究

研究了不锈钢阳极EDTA作络合剂硫酸盐体系锌锰合金电沉积的工艺条件,考察了各工艺条件的影响情况,电流效率比文献报道提高50％。镀层光亮,镀液稳定。     

Electrodeposition of Copper-Containing Polymer Coatings from Sulfate Electrolytes Containing N-Methylpyrrolidone

In sulfate electrolytes for copper plating, N-methylpyrrolidone (MP) was found to form stable 2 : 1 complexes with the metal. The nature of electroactive species at the copper cathode depends on the MP concentration. In a concentration range from 10⁻⁴ to 10⁻² mol/l, the electrode reaction involves complexes of discharging metal ions with adsorbed MP molecules, the complexes being formed in the surface layer. At higher MP concentrations, a slow chemical step associated with dissociation of complex species in the bulk of the solution precedes ion discharge. The inhibitive effect of MP on copper electrodeposition is due to adsorbed MP molecules at the electrode; the adsorption value determines the efficiency of the additive and the wear resistance of the coating. __________ Translated from Zashchita Metallov, Vol. 41, No. 5, 2005, pp. 463–466. Original Russian Text Copyright ? 2005 by Kuznetsov, Skibina, Kuznetsova, Loskutnikova, Sokolenko.     

柠檬酸钠对Zn-Ni-Mn合金电沉积行为的影响

目的通过研究柠檬酸钠对Zn-Ni-Mn合金电沉积行为的影响,明确影响合金电沉积行为的决定性因素,并找出最大电极反应速率对应的柠檬酸钠浓度。方法采用循环伏安法(CV)、旋转圆盘电极(RDE)、电化学阻抗谱(EIS)、计时电流法(CA),对不同柠檬酸钠浓度下Zn-Ni-Mn合金电沉积行为进行研究,采用扫描电镜(SEM)、能谱仪(EDS)对Zn-Ni-Mn合金的表面形貌和成分进行表征。结果 CV分析得出,Zn-Ni-Mn合金的电沉积是一个不可逆过程,当柠檬酸钠浓度为0.6mol/L时,合金共沉积还原峰电位最正(-1.642 V,vs. Ag/Ag+)。RDE分析结果表明,Zn-Ni-Mn的电沉积受动力学和扩散过程混合控制,随着柠檬酸钠浓度的增大,沉积受扩散控制的程度减弱。EIS分析得出,Zn-Ni-Mn合金沉积的电极反应速率由吸附态中间产物造成的弛豫和离子扩散共同决定,当柠檬酸钠浓度为0.6 mol/L时,阻抗谱低频端出现了感抗弧,使极化电阻(Rp)减小并达到最低值(349.68Ω·cm2)。CA分析表明,Zn-Ni-Mn合金的形核速率随柠檬酸钠浓度的增大而降低,成核机理由瞬时成核向连续成核转变。SEM与EDS分析表明,随着柠檬酸钠浓度的增大,合金晶粒尺寸逐渐变大。随着合金中Mn含量的减少,晶粒由胞状转变为多边形状。合金中Zn含量的变化规律与电极反应速率的变化规律相一致。结论电解液中Zn~(2+)的主要存在形式对Zn-Ni-Mn合金的电沉积行为起着决定性作用;当柠檬酸钠浓度为0.6mol/L时,Zn~(2+)主要以[ZnHCit]-的形式存在,其中间产物[ZnHCit~(2-)]ads吸附在阴极表面,大大削弱了浓差极化,电极反应速率最快。     

The Electrodeposition of Cobalt–Chromium Alloys from Sulfate–Oxalate Solutions

The kinetics of separate and concurrent discharge of cobalt and chromium ions from sulfate–oxalate solutions is studied. Cobalt–chromium alloys with the cobalt content of 4 to 94% and carbon content of 1 to 4% are obtained. At a concurrent discharge of chromium and cobalt ions, the deposition potential of chromium is shifted by 150 to 200 mV in the positive direction. The shift depends on the current density and cannot be accounted for by the energy of mixing of the components. The alloying of chromium with cobalt decreases the overpotential of the hydrogen discharge. The codeposition with chromium did not decelerate the reduction of cobalt ions in contrast to the electrodeposition of nickel. The main reasons for the difference between the effect the alloying with chromium produces on the electrochemical reduction of nickel and cobalt, which are similar in their properties, are considered.     

受BTA保护的白铜在模拟工业大气环境中的腐蚀行为

以涂盐沉积的方式进行室内加速实验,通过SEM/EDS、XRD和电化学测试等分析技术,研究受苯并三氮唑(BTA)保护的白铜在模拟工业大气环境中的腐蚀行为。结果表明,腐蚀初期受BTA保护的白铜表面存在棱状的盐结晶,说明腐蚀介质无法完全渗入基体。随着腐蚀时间延长,其对应的腐蚀电流密度呈现先减小后增大的趋势,其原因在于表面除了BTA化学转化膜还存在因腐蚀而产生的氧化膜,2者的共同作用延缓了腐蚀的进行,而当局部的BTA膜层因不断消耗出现破损,腐蚀区域则会从此处开始扩展,腐蚀电流密度也会随之增加。对比BTA处理前后的白铜,虽然最终的腐蚀产物主要成分均为ZnSO₄·6H₂O和Cu₄(SO₄)(OH)₆,呈现为疏松多孔状,但从截面形貌和动力学曲线分析,受BTA处理后的白铜腐蚀程度更轻微。     

The Electrodeposition of Gold and Other Alloys by a New Method

The difficulties of electrodepositing an alloy of a required composition by control only of the chemical composition of the solution may be largely overcome by arranging the solution composition so that one constituent metal is preferentially deposited, but rapidly exhausted, from the cathode film. By applying a pulsed D.C. current all the preferentially deposited metal is deposited from the cathode film in each pulse, together with some of the second metal; conditions are restored by diffusion of ions during the rest period. By adjustment of the actual and relative on- and off-current times the average composition of the alloy can be adjusted without change of composition of the solution, or to allow for unintentional changes in the solution.

Examples of the application of the method to electrodeposition of brass and of gold alloys are given. It has also been found that the brightness of electrodeposition of gold alloys can be maintained to a greater thickness by short-circuiting the anode and cathode during the off-current periods.

Suitable switching apparatus for the pulsed current is described.     

Electrodeposition of Rare Earth Metals and Their Alloys

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Studies on the Electrodeposition of Ternary Copper-Zinc-Tin Alloys

The colour of Cu-Zn-Sn alloy coatings obtained by electrodeposition may differ-white, gold, dark gold, pink, and so on—depending on the specific combination of deposition conditions such as electrolyte composition, temperature, pH value and current density. Effects of pH and current density on the colour of the deposits and the associated electrode processes at the cathode and anode during deposition have been investigated. It was found that increasing either pH or current density causes an increase in the Zn content of the deposit and results in a colour trend away from pink and towards yellow. It was also found that cathodic deposition takes place in the sequence Sn, Cu, Zn, followed by Cu-Zn-Sn alloy. Anodic dissolution occurs at—1.0 V. From this study a reproducible gold-coloured coating was achieved, which could be of considerable practical importance.     

Dissolution Behaviour and Electrodeposition of Strontium and its Alloys

The electromotive force(EMF)was determined by electrochemical method at 760～950℃ for the concen-tration cell:(Mo)Sr|SrCl_2,--Sr sat.||SrCl_2,--xSr|Mo. The dissolution behavior of Sr and alloyed strontium(i.e.Cu--Sr or Al--Sr) in molten salt containing SrCl_2 was studied. The electrolysis of SrCl_2 for production ofSr and its alloys(Al-Sr and Cu-Sr) was also conducted on the basis of electrochemical measurement. The disso-lution data so obtained well agree with the results from phase diagram.     

On the Electrodeposition of Tungsten-Cobalt Alloys From Aqueous Solutions

Sound coherent deposits of tungsten-cobalt alloys with up to 60–66 wt. % of tungsten can be produced at cathode current efficiencies of up to 21% from solutions containing 40–70 g./l. of tungsten as sodium tungstate, 4–12 g./l. of cobalt as cobalt sulphate, 70–150 g./l. of citric acid and 50 g./l. of ammonium chloride, adjusted to room-temperature pH of 7·5–8·5 with sodium hydroxide, and operated at 50–70° C. with interrupted d.c. pulses of 0·05–2 sees, and equal or rather greater “off” periods, the cathode current density during the pulses being 5–20 amps./dm.². Moderate agitation of the solution is desirable.

Hydrogen overpotential for hydrogen deposition from citrate buffers is much less on tungsten-cobalt cathodes than on tungsten or cobalt cathodes. Evidently the electronic structure of the alloy cathodes is much more favourable than that of tungsten for hydrogen deposition: this suggests that it is also more favourable for tungsten deposition, which may help to explain why tungsten-cobalt alloys are so much more easily deposited than pure tungsten.

A number of amphipathic organic molecules, among them thiourea, benzenesulphonamide and pyridine, increase the hydrogen overpotential on tungsten-cobalt alloys: but they do not increase the cathode current efficiency of alloy deposition, evidently because they increase the metal-deposition overpotential about equally.     

电沉积镍钼基合金析氢电极材料的研究进展

本文简要介绍了电沉积晶态、纳米晶、非晶态和复合镍钼基合金电极的研究现状,从几何因素上分析了不同表面结构的电极性能,并对比分析了相同表面结构下的二元、三元甚至多元镍钼基合金电极的电催化活性.最后指出探究非晶态与纳米晶混合结构的形成和析氢机理是今后研究电极材料的重要方向.     

The Electrodeposition of Zinc on Aluminium and Its Alloys

Dull nickel deposits may be given a brilliant finish by a brief anodic treatment in a sulphuric acid solution; polishing action is obtained over a wide range of conditions. The method has possibilities as an alternative to bright nickel plating and the process has been investigated from this point of view. Under suitable conditions, the process does not adversely affect the protective properties of the deposit and the quality of the finish is at least as good as that obtained by bright nickel plating. The method also enables designs to be formed on nickel surfaces by localising the area polished, and attractive finishes may be produced in this way.     

电沉积镍钼基合金析氢电极材料的研究进展

本文简要介绍了电沉积晶态、纳米晶、非晶态和复合镍钼基合金电极的研究现状,从几何因素上分析了不同表面结构的电极性能,并对比分析了相同表面结构下的二元、三元甚至多元镍钼基合金电极的电催化活性。最后指出探究非晶态与纳米晶混合结构的形成和析氢机理是今后研究电极材料的重要方向。