A study on electroplating of zinc nickel alloy with HEDP plating bath

The electroplating of bright Zn-Ni alloy process using HEDP as coordinating agent, ZNP as additive agent is studied. The effect of coordinating agent, chloride content, [Zn²⁺]/[Ni²⁺], cathode current density, temperature, and supplementary coordinating agent on Ni content is investigated; composition and physical phase of alloy plating layer, brightness of plating layer, and stability of plating solution are comprehensive considered; and also, the optimum composition of plating solution for bright Zn-Ni alloy electroplating and technological condition is determined; finally, deposition mechanism is discussed. Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 1, pp. 25–30. The text was submitted by the authors in English.     

Electrochemical deposition of mesoporous nickel hydroxide films from dilute surfactant solutions

A series of micelle-templated mesoporous nickel hydroxide films were prepared by electrochemical deposition from dilute surfactant solutions by using different types of template and by varying plating solvent composition. Lamellar mesostructured Ni(OH)2 films are obtained with only anionic surfactant sodium dodecyl sulfate (SDS) as the template. In particular, a unique cooperative assembly fashion, that is, the combination between Ni2+ and a complex composed of the primary template SDS and a cosurfactant, such as triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) copolymers and poly(ethylene glycol), was explored, by which two-dimensional hexagonal mesoporous Ni(OH)2 films were electrodeposited. Meanwhile, the deposition medium also plays a crucial role in determining the mesostructure of Ni(OH)2 films. For the composite nickel hydroxide films deposited from aqueous solution or dilute aqueous solution of ethylene glycol (<20 wt %) in the presence of SDS or the SDS-poly(alkylene oxide) polymer complexes, a mixed lamellar phase with d(001) = 37.4 A and d(001) = 28.5 A was obtained. However, single lamellar phase with d(001) = 37.4 A was electrodeposited from concentrated aqueous solutions of ethylene glycol (> or = 20 wt %). Furthermore, such deposition baths have access to hexagonal mesoporous nickel hydroxide films with d(100) = 37.4 A at 70 degrees C with the SDS-poly(alkylene oxide) polymer complexes as the templates. Within the potential window for Ni(OH)2, the morphology and quality of mesostructured films are significantly dependent on the deposition potential, while the mesostructures of the composite films always remain unchanged.     

Electrodeposition mechanism of nickel films on polycrystalline copper from dilute simple sulphate solutions

In this paper, we have studied the mechanism of nucleation and growth of nickel from a simple sulfate bath on polycrystalline copper (Cu) substrate. Cyclic voltammetry technique and current transients recorded during electrodeposition of nickel on Cu were used to evaluate the electrochemical deposition of nickel on copper. Results show that nickel starts to grow on copper from a typical potential of −0.7 V vs. Ag/AgCl. Increasing scan rate of cyclic voltammograms shifts the reduction peaks towards a more negative values. We plotted non-dimensional graphs according to the Scharifker-Hills theory and concluded an instantaneous nucleation and growth mechanism for nickel elecrodeposited on copper based on our experimental conditions.     

Possible reasons for the appearance of metallic phase in electroless nickel plating solutions

The growth of Ni-P coatings was studied in the “stable” electroless nickel plating solution and in the “decomposed” solution containing in its bulk a sufficient amount of the metallic phase particles.     

A flame spectrophotometric method for the determination of nickel and boron in plating solutions

The flame photometric method as a rapid means of estimating the nickel and boron concentrations in nickel plating solutions is described. The effect of methanol concentration upon the flame emission of the 352.5 mμ nickel line in 1 to 1 methanol—water solution was studied. The effect of nickel concentration upon the flame emission of boron in 1 to 1 methanol —water solution was studied for the oxide band system at 518 mμ.On étudie l'effet de la concentration du méthanol sur la flamme d'émission de la raie 352.5 mμ du nickel dans un mélange eau —méthanol 1:1.L'effet de la concentration en nickel sur la flamme d'émission du bore dans un mélange eau —mé -thanol 1:1 est étudié pour les bandes de l'oxyde á 518 mμ     

The preparation of nickel oxide based on infinite dilute method and its electrochemical performance

With NaOH as precipitation agent and NiSO₄ · 6H₂O as raw material, Ni(OH)₂ particles were synthesized by infinite dilute method and sintered at 300°C for NiO. The synthesized NiO particles with a structure of cubic crystalline phase are well dispersed and ball-flower like with a diameter of 500 nm. The electrochemical tests show that the NiO particles have relatively high capacitance and excellent capacitive retention. The good structure and excellent performance suggest its promising application in supercapacitors.     

Throwing power of a dilute sulfuric acid copper plating electrolyte during intensive electrodeposition

A method of determination of the throwing power (TP) of electrolytes in conditions of forced convection in a Hull cell with a rotating cylindrical electrode is presented. The method is used to determine TP of a copper plating electrolyte containing 0.15–0.5 M CuSO₄ and 1 M H₂SO₄ at current densities of up to 75 mA cm^-2. The TP decreases with increasing current density at a constant i _av/i _d ratio, where i _av is the average working current density and i _d the limiting diffusion current density. With increasing the i _av/i _d ratio due to an increase in the cathodic polarizability conditions for an increase in TP may be achieved. In optimum (for uniform deposition) modes, i _av/i _d 0.4–0.5. The TP may increase upon diluting electrolyte with respect to its main component.Translated from Elektrokhimiya, Vol. 41, No. 1, 2005, pp. 91–96.Original Russian Text Copyright © 2005 by Dikusar, Bobanova, Yushchenko, Yakovets.To the Centennial of B.N. Kabanov.     

缓冲剂对镀镍过程作用机理的研究

缓冲剂对镀镍过程作用机理的研究①高灿柱鹿玉理刘汝涛陈方（山东大学环境工程系济南２５０１００）李树本（中国科学院兰州化学物理研究所兰州７３００００）电镀镍是量大面广的镀种，它作为镀铬、贵金属、仿金、枪黑、黑镍的底层，用途非常广泛［１］．在镀镍过程中，...     

Ion-exchange recovery of nickel(II) from wash water formed in electroless plating in acid hypophosphite solutions

Kinetic aspects of extraction of Ni(II) ions with KU-2–8 cation-exchange resin in the Na⁺ form from wash water produced in electroless nickel-plating were studied. The optimal conditions and parameters of ion-exchange purification and regeneration of the cation-exchanger were determined.     

Sucrose clusters exhibiting a magic number in dilute aqueous solutions

We report clustering of sucrose molecules in dilute aqueous solutions, based on measurements of the electrical mobility spectrum of singly charged airborne clusters produced by electrospraying the solution. The spectrum contains peaks with a smooth envelope, except for one peak which has about twice the amplitude of the envelope. The mobility at this peak is found to be somewhat higher than would be expected based on the rest of the sequence, suggesting a more compact structure for this cluster. This "magic" peak is prominent for basic, but not acidic, solutions. It is argued that these observations demonstrate the existence of clusters of many sizes in the solution prior to electrospraying, including the "magic" cluster. A simplified model is presented which reproduces the observed features.     

Electrochemical modification of Bi2S3 coatings in a nickel plating electrolyte

The electrochemical behavior of Bi₂S₃ coatings in Watts nickel plating electrolyte was investigated using the cyclic voltammetry, electrochemical quartz crystal microbalance, X-ray diffraction, and energy dispersive X-ray analysis methods. During the bismuth sulfide coating reduction in Watts background electrolyte in the potential region from −0.4 to −0.6 V, the Bi₂S₃ and Bi(III) oxygen compounds are reduced to metallic Bi, and the decrease in coating mass is related to the transfer of S²⁻ ions from the electrode surface. When the bismuth sulfide coating is reduced in Watts nickel plating electrolyte, the observed increase in coating mass in the potential region −0.1 to −0.4 V is conditioned by Ni²⁺ ions reduction before the bulk deposition of Ni, initiated by Bi₂S₃. In this potential region, the reduction of Bi(III) oxygen compounds can occur. After the treatment of as-deposited bismuth sulfide coating in nickel plating electrolyte at E = −0.3 V, the sheet resistance of the layer decreases from 10¹³ to 500–700 Ω cm. A metal-rich mixed sulfide Ni₃Bi₂S₂–parkerite is obtained when as-deposited bismuth sulfide coating is treated in Watts nickel plating electrolyte at a potential close to the equilibrium potential of the Ni/Ni²⁺ system and then annealed at temperatures higher than 120 °C.     

Adsorption of polypropylene from dilute solutions on a zeolite column packing

Faujasite type zeolite CBV-780 was tested as adsorbent for isotactic polypropylene by liquid chromatography. When cyclohexane, cyclohexanol, n-decanol, n-dodecanol, diphenylmethane, or methylcyclohexane was used as mobile phase, polypropylene was fully or partially retained within the column packing. This is the first series of sorbent-solvent systems to show a pronounced retention of isotactic polypropylene. According to the hydrodynamic volumes of polypropylene in solution, macromolecules of polypropylene should be fully excluded from the pore volume of the sorbent. Sizes of polypropylene macromolecules in linear conformations, however, correlate with the pore size of the column packing used. It is presumed that the polypropylene chains partially penetrate into the pores and are retained due to the high adsorption potential in the narrow pores.     

Hydrodynamic and conformational properties of a hyperbranched polymethylallylcarbosilane in dilute solutions

The hydrodynamic and conformational properties of a hyperbranched polymethylallylcarbosilane in hexane solutions have been studied by light scattering, sedimentation, translational diffusion, and viscometry. Fractions with M = (1–75) × 10³ have been used in experiments. The solution behavior of the hyperbranched polymer significantly differs from the properties of both spherical particles and linear polymers. The shape of hyperbranched polymethylallylcarbosilane macromolecules differs from spherical—the asymmetry factor is p ≤ 1.5. Polymethylallylcarbosilane macromolecules in solutions are characterized by compact structure—the hydrodynamic radius is not higher than 4 nm at M = 75 × 10³.     

Thermodynamic properties of dilute solutions of carbon monoxide in a hydrocarbon

Partial molar volumes, enthalpies, entropies, and energies have been obtained for dilute solutions of carbon monoxide in liquid benzene and in liquid n-octane up to 523 K and 15 MPa. As for (hydrogen + a hydrocarbon), the ratio $\text{a}{}_{12}\text{a}{}_{11}$ of the cohesive energy densities is independent of hydrocarbon type.     

Highly-dispersed Ta-oxide catalysts prepared by electrodeposition in a non-aqueous plating bath for polymer electrolyte fuel cell cathodes

The Ta-oxide cathode catalysts were prepared by electrodeposition in a non-aqueous solution. These catalysts showed excellent catalytic activity and have an onset potential of 0.92 V(RHE) for the oxygen reduction reaction (ORR). The highly-dispersed Ta species at the nanometer scale on the carbon black was an important contributor to the high activity.     

Separation, recovery and recycling of a fluorous-tagged nickel catalyst using fluorous solid-phase extraction

Highly efficient separation, recovery and recycling of the fluorous-tagged catalyst, [Ni[F13C6C(O)CHC(O)C6F13]2], can be achieved with fluorous solid-phase extraction, after the Lewis acid catalysed synthesis of enaminodiones in conventional organic solvents.     

Dielectrophoresis: a model to transport drugs directly into teeth

The article describes an innovative delivery system based on the principles of dielectrophoresis to transport drugs directly into site-specific intraoral targets. The hypothesis that a drug can be driven into tooth enamel during the application of an applied electrical potential difference was tested by the authors in in vitro studies comparing dielectrophoresis to diffusion to transport carbamide peroxide and fluoride. The studies showed that these agents can be transported directly into teeth using an alternating current (AC) electric field more effectively than diffusion. It was found that a 20-min bleaching treatment on human teeth with dielectrophoresis increased carbamide peroxide absorption by 104% and, on average, improved the change in shade guide unit 14 times from 0.6 SGU to 9 SGU. After applying a 1.23% acidulated phosphate fluoride gel to bovine incisors for 20 min by dielectrophoresis or diffusion, analysis with wavelength dispersive spectrometry determined that dielectrophoresis doubled fluoride uptake in the superficial layers compared to diffusion, and drove the fluoride significantly deeper into enamel with an uptake 600% higher than diffusion at 50 μm depth. Finally, dielectrophoresis promises to be a viable model that can potentially be used clinically to deliver other targeted drugs of variable molecular weight and structure.     

Automated dilution in flow injection analysis with double on-line dialysis. A system for the determination of chloride in industrial effluents and plating bath solutions

Summary An automated on-line system for the determination of chloride in industrial effluents and plating bath solutions based on the concept of flow injection analysis is described. Samples with a very high chloride content up to 6 g/100 ml (60 g/l) are analysed by using an automated in-manifold double on-line dialysis technique. The sampling rate is 100 samples per hour. The method is suitable for the analysis of chloride with a relative standard deviation of better than 0.8%. The measurement is based on the red-coloured iron thiocyanate complex.