Observation of initial deposition process of electroless nickel plating by quartz crystal microbalance method and microscopy

The initial deposition process of electroless nickel plating was investigated by combining a quartz crystal microbalance (QCM) method with microscopy. The authors found an anomalous deposition rate in the initial deposition and four stages were noted: an induction period before the initiation of deposition, an acceleration period with an increase in the deposition rate, a deceleration period with a decrease in the deposition rate and a stationary period at a constant deposition rate. The practical surface area of the deposits increased until the deposits became continuous and reached a constant value. On the other hand, the deposition rate per unit practical surface area decreased monotonously as the deposition proceeded. As a result, an anomalous initial deposition rate was observed. The four periods also appeared in the deposition when the catalyzation process was repeated 4 times. In this case, the number of grains at the initial stage was greater, and nucleation still continued until the deposits became continuous. The initial deposits, therefore, became continuous at lower thickness.     

化学镀镍磷合金镀速的研究

研究了化学镀镍磷合金中镀液成分及操作条件对金镀层沉积速度的影响。     

Hydrogen incorporation in Ni–P films prepared by electroless deposition

Electroless NiP films, with 12 to 16 wt % P, were deposited from a moderately acid solution. Thermogravimetric analysis indicates the presence of occluded hydrogen in the layers, which desorbs upon heating. The amount of incorporated hydrogen decreases when the pH of the solution or the nickel sulfate concentration is increased; by contrast it increases with hypophosphite concentration. Cyclic voltammetry, using an electrochemical quartz crystal microbalance, confirms the existence of parasitic reactions, namely the reduction of protons of the solvent during the cathodic process and oxidation of hydrogen during the dissolution of the layers. This behaviour is in qualitative agreement with the proposed reaction scheme.     

影响ABS塑料化学镀Ni-Cu-P合金沉积速度的因素探讨

采用化学镀制备了含Ni53．11％、Cu37．8％、P9．09％的Ni-Cu-P三元合金。研究了铜盐、镍盐及络合剂含量,还原剂, pH和施镀温度对该镀层沉积速度的影响。实验结果表明镀速随硫酸镍浓度、次磷酸钠浓度、施镀温度及镀液pH的升高而增加,随硫酸铜浓度、络合剂浓度的升高而降低。并得出的最佳工艺配方及工艺条件为:3．5 g／L硫酸铜,33 g/L硫酸镍, 24 g/L次磷酸钠,64 g／L柠檬酸钠,20 g／L无水醋酸钠,稳定剂适量,温度80℃,pH 8．00．2。     

化学镀工艺对Co-B功能膜沉积速率与结构的影响

以硫酸钴为主盐、硼氢化钠为还原剂制备了Co-B合金功能膜。主盐及还原剂的质量浓度增大都会加快沉积速率,但当两者超过一定值时,沉积速率反而下降。pH的增大和温度的升高也会加快沉积速率,而配位剂(酒石酸钠)质量浓度的增大,则会降低沉积速率。X射线衍射实验结果表明,化学镀Co-B合金在镀态下是非晶态。温度升高、主盐质量浓度增大及配位剂质量浓度减小都使镀层有形成晶态的趋势。原子力显微镜(AFM)照片显示:镀层表面由球状突起颗粒构成,颗粒尺寸为0.6~2μm。     

化学镀铜溶液中稳定剂与铜沉积速率的关系

研究了化学镀铜溶液中稳定剂对铜沉积速率的影响,着重考虑主配位剂、副反应的抑制剂、甲醛捕获剂对化学镀铜的影响。结果表明,在基本配方8 g/L CuSO4.5H2O,3 g/L HCHO2,8 g/L EDTA7,.5 g/L NaOH,工艺参数pH=12.5,温度50℃,时间40 min的基础上,各种稳定剂的适宜用量为6 mL/L CH3OH、8 mg/L K4Fe(CN)6、6 mg/L 22,’-bipy。在最佳工艺下得到的镀层外观红亮,表面平整,晶粒细致,化学镀铜液稳定。     

The observation of the nucleation and growth of electrolessly plated nickel deposited from different bath pH by TEM and QCM method

The important factors for fabricating thinner and more uniform films by electroless plating were discussed. Two kinds of Ni-P films were electrolessly plated from hypophosphite baths. The number density of the grains was low in the Ni-5.3 wt%P deposits which were plated from the pH 9 bath. As deposition proceeded, the grains grew and merged to form a continuous structure. In case of the Ni-12.6 wt%P deposits, which were plated from the pH 6 bath, the number density of the grains was more than twice that of the Ni-5.3 wt%P deposits. The grains formed a continuous structure, with nucleation governed by the initial deposition. Thus, the transition thickness, i.e., the thickness at which the deposits assumed a continuous structure, was lower in the case of pH 6. The difference was caused by the different autocatalytic activity of the deposits due to the difference in phosphorus content. It was found that the thinner and more uniform nickel films could be electrolessly plated under lower autocatalytic activity.     

The activation effect of Pd nanoparticles on electroless nickel-phosphorous deposition

Active colloids regarding responsible for charge transfer and electron transfer are in electroless metal bath. Herein, the electrochemical analysis for the catalytic effect of Pd nanoparticles on deposition kinetic and microstructure in the electroless nickel-phosphorous bath was studied. As supported analysis by leaner sweep voltammetry (LSV), the currents for oxidation peaks corresponding to Pd nanoparticles of increasing amount are measured to be enhanced. It shows that Pd nanoparticles have excellent catalytic power for EN_pD bath. In addition, the deposition rate analyzed by mixed potential theory (MPT) was found and increased from 0.063 to 0.091 μg/cm² s. However, based on the same nanocatalyst quantity, the deposition rates which actually occurred and are in situely monitored by EQCM are measured to be faster than theoretical value given by MPT. It shows that that the cathodic currents for depositing hydrogen and phosphorous in mixed potential theory could not be neglected when the equilibrium potential reached. As an additional information supported by FE-SEM, the continuous growth of nickel crystal is found after the induction time measured by EQCM. The narrowest distribution of nanosize grain is obtained at 120 s. In addition, the deposited layer of P of higher content is found to exist in the deposited microstructure catalyzed by the Pd nanoparticles of high concentration.     

化学沉积纳米晶Co-P合金及其沉积速率影响因素的研究

化学沉积可得到均匀、致密的纳米晶薄膜,是一种较为理想的纳米晶制备方法。采用正交实验优化了化学沉积纳米晶钴磷合金的工艺配方,研究了正交实验5因素如硫酸钴、柠檬酸三钠、硼酸、次磷酸钠和温度及负载因子、沉积时间对沉积速度的影响。研究获得的优化工艺配方和参数为:0 06～0 12mol/LCoSO4·7H2O,0 40～0 55mol/LNaH2PO2·H2O,0 15～0 3mol/LNa3C6H5O7·2H2O,0 3～0 6mol/LH3BO3,50～80℃,负载因子0 4～0 8dm2/L。     

化学镀法制备尾气催化剂的催化性能研究

采用浸渍法和化学镀法将Pd负载到涂浆后的载体上,利用催化剂活性评价装置对两种方法制备的催化剂进行活性评价。结果表明,铈锆镧复合氧化物固溶体结构形式存在,而且有较好的热稳定性;氧化铝前驱体650℃焙烧2h后形成了γ-Al2O3;化学镀法制备的催化剂催化性能优于浸渍法;化学镀法制备催化剂二次评价后,活性有所降低;经过高温老化处理后对CO氧化仍然有比较好的催化选择性。     

柠檬酸对Ni-P合金化学镀沉积速度和镀层性能的影响

研究了柠檬酸浓度对乙酸盐缓冲体系Ni-P合金化学镀沉积速度、镀层含磷量及其耐蚀性与结构的影响，并对镀层在镀态下和经热处理后的耐蚀性与结构进行了比较。结果表明，随柠檬酸浓度的增加，沉积速度先增加后l牵低，而镀层中磷含量则先降低后增加；镀态时高磷合金为非晶态结构且具有较好的耐蚀性，中磷合金则为非晶 微晶结构，耐蚀性较低，而所有镀层经350℃热处理1h后，结构都转变为晶态，且耐蚀性明显提高。     

Study on photocatalytic deposition of bismuth onto nanocrystalline TiO2 by quartz crystal microbalance and electrochemical method

In situ techniques of quartz crystal microbalance (QCM), differential pulse voltammetry (DPV) and amperometric measurement were employed to investigate the adsorption Bi(III) ions and the photocatalytic deposition Bi process at the surface of nanocrystalline TiO₂. It was obtained that the adsorption of Bi(III) ions onto nanocrystalline TiO₂ accords with the pseudo-second-order reaction and the reaction rate constant k was about 13.3 g mol⁻¹ min⁻¹. In addition, the photocatalytic deposition of Bi onto the surface of TiO₂ was further investigated. It was found that photocatalytic deposition rate at the surface of TiO₂ was enhanced by increasing pH value or initial concentration of Bi(III) ions. The influence of organic hole-scavegeners on the photocatalytic deposition of Bi was also investigated, and it was obtained that formic acid may be the best for the photocatalytic reduction of Bi. The mass ratio between the Bi(III) and Bi metal deposition was calculated as 7.48:1. Therefore, it can be concluded that QCM, DPV and amperometric measurement may be effective and reliable for the investigation of the photocatalytic deposition of Bi onto the surface of nanocrystalline TiO₂.     

Synthesis of monodisperse nickel‐coated polymer particles by electroless plating method utilizing functional polymeric ligands

In the electroless plating process, to omit a sensitizing process with SnCl₂, we utilized amino‐functional groups on polymer particles. At first, highly monodisperse functional polymer particles could be prepared by a two‐step seeded polymerization of styrene, divinylbenzene, and glycidyl methacrylate. Then, surface epoxy‐functional groups were converted to amino‐functional groups by treating the particles with a diamine. By using these surface amino functionalities, we tried to prepare uniformly metal‐coated monodisperse polymer particles by electroless plating method. The constituents of an electroless nickel solution bath are nickel salt, a reducing agent, suitable complexing agents, and stabilizers. And the metal thickness was simply controlled by changing the loading amount of substrate polymer particles. Morphological observation of nickel‐plated polymer particles was conducted by using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The structural composition of plated nickel was also investigated. Most of all, the function and the efficiency of the amino‐functional group of polymer particles as a polymeric ligand for metal binding was elucidated. From all observations, it was evident that in the electroless metal plating process without any sensitization step, the deposition of metal clusters on substrate particles is largely dependent upon the particle surface functionality. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3801–3808, 2006     

超声波化学镀Ni-Cu-P合金

在有机高分子聚合物薄膜,如投影仪专用胶片上超声波化学镀M—Cu—P合金,研究了镀液各组分浓度、pH值变化对沉积速度的影响：通过扫描电镜(SEM)观测镀层的表面形态及厚度,并用其所附带的能谱(EDS)分析镀层成分,采用透射电镜(TEM)观测镀层中粒子的微观形貌及大小,利用X-射线衍射(XRD)表征镀层的微观结构。结果表明,M—Cu—P合金化学镀层为非晶态合金,光亮、均匀,与基体结合面平整：镀层厚度100μm,镀层颗粒大小在30～40nm,各成分含量分别为77．73％～90．64％Ni,0．38％～5．27％Cu,7．23％～14．30％P。     

N,N−二甲基−二硫代甲酰胺丙磺酸钠对THPED体系化学镀铜的影响

研究了N,N?二甲基?二硫代甲酰胺丙磺酸钠(DPS)作为添加剂对以四羟丙基乙二胺(THPED)为单一配位剂的化学镀铜体系的沉积速率、镀层形貌和晶体结构的影响。结果发现,当DPS的质量浓度从0 mg/L增大到1.0 mg/L时,沉积速率从2.91μm/h提高到6.73μm/h,所得镀层结晶均匀、细致。线性扫描伏安测量结果表明,DPS是通过促进甲醛的阳极氧化来加速化学镀过程。本体系的Cu镀层主要呈面心立方多晶取向,DPS的添加会令晶面取向从(220)转变为(111)。     

Fabrication and microwave properties of Ni hollow powders by electroless plating and template removing method

Using activated carbon as templates, Ni coated activated carbon powders were prepared by electroless nickel-plating method. Removing the activated carbon templates, nickel hollow powders were prepared. The prepared Ni coated activated carbon powders and nickel hollow powders were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), and Field emission scanning electron microscope (FESEM). The results show that most of the activated carbon template could be eliminated at 210 °C in air or at 700 °C in nitrogen without oxidation of most of the coated nickel. The Ni hollow powders heated in air showed more porous than that of annealed in nitrogen. The dielectric and magnetic loss of Ni hollow powders -paraffin wax composites were measured in the frequency range of 2-15 GHz by reflection/transmission way using network analyzer. The reflection coefficient of Ni hollow powders-paraffin wax absorbers with 2 mm thickness was calculated by transmission line theory, the maximum reflection loss can be up to − 16 dB.     

Monodisperse polymer/metal composite particles by electroless chemical deposition: Effect of surface functionality of polymer particles

Micron‐sized polymer particles were coated with layers of nickel compounds by plating electrolessly in the presence of aqueous solutions of nickel chloride, sodium hypophosphite, sodium citrate, and ammonium chloride at elevated temperature. The uniform functional polymer particle could be obtained by seeded polymerization. To investigate the effect of surface functionality on the conditions for nickel deposition, the polymer particle was functionalized with the thiol group. From morphological observation, it was found that the mode of nickel deposition was greatly dependent on the surface functionality of the polymer particle. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 420–424, 2003     

Investigation of a transparent chromate (III) passive film on electroless Ni–P coating by XPS and electrochemical methods

A transparent passive film on electroless nickel phosphorus coating (ENPC) was obtained in a chromate (Cr³⁺) bath. An ENPC sample passivated in a Cr⁶⁺-containing bath was used for comparison. The corrosion properties were tested by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). SEM, XPS, and EDX were employed to analyze the chemical composition and surface morphology of the films. SEM results indicate that the passive film is too thin to be observed by SEM. The potentiodynamic polarization tests show that the corrosion currents of the two passivated samples are only about 1/25 of the un-passivated coating. The XPS analysis illustrate that the Cr⁶⁺-treated film comprises Cr, Ni and O, while the Cr³⁺-treated film is made up of Cr, C, O, Ni, P and N. High-resolution XPS analysis show that, both in Cr⁶⁺-treated and Cr³⁺-treated films, element Cr is only in the form of trivalent compounds, no hexavalent chromium existing. By XPSpeak analyzing, trivalent chromium compounds on the two treated surfaces were fitted as Cr(OH)₃ and Cr₂O₃. However, for the Cr³⁺ and Cr⁶⁺ passivation routes, the Cr(OH)₃ and Cr₂O₃ contents in passive films are widely divergent.     

Evaluation of the Performance of Carbon Supported Pt–Ru–Ni–P as Anode Catalyst for Methanol Electrooxidation

This research is aimed to improve the activity and stability of ternary alloy Pt–Ru–Ni/C catalyst. A novel anodic catalyst for direct methanol fuel cell (DMFC), carbon supported Pt–Ru–Ni–P nanoparticles, has been prepared by chemical reduction method by using NaH₂PO₂ as a reducing agent. One glassy carbon disc working electrode is used to test the catalytic performances of the homemade catalysts by cyclic voltammetric (CV), chronoamperometric (CA) and amperometric i–t measurements in a solution of 0.5 mol L^–1 H₂SO₄ and 0.5 mol L^–1 CH₃OH. The compositions, particle sizes and morphology of home‐made catalysts are evaluated by means of energy dispersive analysis of X‐ray (EDAX), X‐ray diffraction (XRD) and transmission electron micrographs (TEM), respectively. TEM images show that Pt–Ru–Ni–P nanoparticles have an even size distribution with an average diameter of less than 2 nm. The results of CV, CA and i–t curves indicate that the Pt–Ru–Ni–P/C catalyst shows significantly higher activity and stability for methanol electrooxidation due to the presence of non‐metal phosphorus in comparison to Pt–Ru–Ni/C one. All experimental results indicate that the addition of non‐metallic phosphorus into the Pt–Ru–Ni/C catalyst has definite value of research and practical application for enhancing the performance of DMFC.