Effect of copper content on the properties of Ni–Cu–P plated polyester fabric

The copper content of electroless Ni–Cu–P-plated polyester fabric mainly depends on the copper ion concentration in the plating solution, which in turn has a significant effect on the properties of the coatings. The effects of copper sulphate concentration (CuSO₄) on the deposition rate, composition, surface morphology, crystal structure, surface resistance and electromagnetic interference (EMI) shielding effectiveness of electroless Ni–Cu–P deposits were investigated. The results show that the copper content in the deposits increased significantly, whereas nickel content decreased significantly and phosphorus content decreased slightly with a higher copper ion concentration. Compact coating layers were obtained with a nodular morphology. With increase of copper ion concentration in the solution, the crystallinity of the deposits also increased. In addition, the surface resistance decreased and the EMI shielding effectiveness of the Ni–Cu–P deposits increased.     

Effect of plating mode, thiourea and chloride on the morphology of copper deposits produced in acidic sulphate solutions

The influence of plating mode, chloride and thiourea (TU) on morphology of copper deposits has been studied. All experiments were conducted on disc electrodes rotating at 500 rpm and an average current density of 4 A dm⁻² to produce 10 μm thick deposits. In additive-free solutions, the use of pulsed current (PC) improved deposit morphology and brightness over DC plating. In the presence of thiourea (no Cl⁻), the deposits obtained by DC and PC plating were similar under most plating conditions. The presence of thiourea generally improved deposit quality over that obtained in additive-free solutions, but caused the formation of microscopic nodules and the deposits to appear slightly cloudy, resulting in lower reflectances than that of a polished uncoated copper surface. The addition of Cl⁻ to thiourea-containing solutions strongly influenced deposit morphology at both microscopic and macroscopic scales depending on chloride concentration and pulse conditions. It prevented nodule formation and created microscopically bright and reflective deposits, but caused extreme macroscopic roughness. Nevertheless, PC plating at 50 Hz in solutions containing appropriate amounts of thiourea and Cl⁻ was found to yield macroscopically and microscopically smooth deposits with reflectance similar to that of a polished uncoated copper substrate.     

Effect of SiC on the corrosion resistance of electroless Cu–P–SiC composite coating

In this work, Cu–P–SiC composite coatings were deposited via electroless plating with the addition of sodium hypophoshite (NaH₂PO₂) as a reducing agent. The coating compositions deposited were determined by using energy dispersive X-ray spectroscopy (EDX). The surface morphology of the coatings that were analyzed using scanning electron microscopy (SEM) showed that SiC particles were uniformly distributed by virtue of surfactant addition and mechanical stirring. The anti-corrosion properties of Cu–P and Cu–P–SiC coatings in NaCl and HCl solutions were investigated by the weight loss and potentiodynamic polarization techniques. The results showed that the corrosion resistance of Cu–P–SiC coatings was superior to that of electroless Cu–P coatings and carbon steel substrates in various concentrations of NaCl and HCl solutions.     

Electroless deposition of copper in acidic solutions using hypophosphite reducing agent

A new bath formulation was developed, which allowed deposition of copper-rich Cu–Ni–P alloys in electroless acidic solutions in the absence of formaldehyde. The reducing agent was sodium hypophosphite. Though cupric ions do not catalyse the oxidation of hypophosphite, we show that, in the presence of a low concentration of Ni(II) species, it is possible, even at low pHs, to induce the reduction of the cupric species. A very strong preferential deposition of copper was observed, which gives Cu–Ni–P layers with copper content up to 97 wt%. The phosphorus content decreased from 13% to 1% with increasing copper content. The plating rate decreased when the copper sulfate concentration in the solution increased. It increased with increasing pH or temperature, but the influence was less pronounced than in alkaline solutions. Compact layers were obtained with a nodular morphology which did not markedly changed with composition.     

Structure,microstructure and corrosion properties of brush-plated Cu–Ni alloy

Cu–Ni alloy coatings on copper substrate by the brush-plating process have been investigated using XRD and AFM. The X-Ray diffraction analysis revealed that the brush-plated Cu–Ni alloy was heterogeneous and composed of cubic Cu_3.8Ni phases. Uniform surface coverage of the substrate by granular morphology was observed from AFM. The corrosion protection performance of the brush-plated Cu–Ni alloy on copper substrate has been assessed using electrochemical corrosion tests. These results indicated a high charge transfer and low I _corr for the alloy system compared with copper deposits and the copper substrate.     

Effect of pulse plating on composition of Sn–Pb coatings deposited in fluoroborate solutions

Galvanostatic pulsed current (PC) and pulse reverse (PR) plating of Sn–Pb coatings onto copper rotating disks from fluoroborate solutions has been conducted to obtain alloy compositions otherwise not achievable by DC plating. PC plating investigated over a wide range of pulse frequencies (20 Hz–200 kHz) and duty cycles produces coatings with compositions that differ only slightly from those obtained by DC plating at the same current density. On the other hand, the use of PR plating can be dramatic, producing Pb contents both well above and below that achievable by DC plating. Varying the frequency from 20 Hz to 200 kHz with the duty cycle and average current density fixed at 80% and 3.78 A dm^–2 yields compositions between 2.5 and 28 wt.% Pb. The Pb:Sn ratio in the deposit is always lower than that in the plating bath when a PR frequency of 20 Hz is imposed, but generally exceeds it at a frequency of 20 kHz. Alloy composition appears to be closely related to the working electrode potential reached during the anodic pulse. A higher frequency leads to less positive potentials during the anodic pulse and shorter anodic pulse times, which may enhance Sn dissolution and enrich the coating in Pb.     

烟酸脉冲镀银及镀层性能的实验室研究

研究了烟酸体系双脉冲镀银的工艺条件对镀层的沉积速率.外观质量、结合力、抗变色能力及表面形貌的影响.在最佳工艺条件下,与丁二酰亚胺镀银工艺进行了比较.结果表明,电流密度为0.25A/dm2、频率为1 000Hz、温度为25℃时,可获得光亮、抗变色能力好的镀层.与丁二酰亚胺体系得到的镀层相比较,烟酸体系镀层性能更优.镀层银晶为立方晶系.     

The effects of pulse plating variables on morphology and corrosion behavior of Zn–Fe alloy coatings

Considerable researches have been focused on zinc–iron (Zn–Fe) alloy coatings due to their superior characteristics among zinc alloy electrodeposits in recent years. The corrosion behavior of these coatings depends on the phase structure and morphology of the Zn–Fe deposits. In this work the effects of pulse plating variables such as current density, off-time, frequency and pulse modes on the morphology and phase structure of Zn–Fe deposits was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometry (EDS) analysis. The corrosion behavior of these coatings was measured by means of polarization curves and Neutral salt spray tests. It was shown that pulse reverse coatings exhibit excellent resistance to corrosion in comparison with normal pulse and direct current conditions.     

Electrodeposition and corrosion behavior of Zn–Ni and Zn–Ni–Fe2O3 coatings

A thin film of Zn–Ni–Fe₂O₃ on steel substrates was prepared by electrodeposition technique using Zn–Ni alloy plating solution with nano-sized Fe₂O₃ particles. The cathodic polarization and cyclic voltammetry techniques were used to explain deposition process. The corrosion behavior of deposits was evaluated by polarization and impedance studies. Scanning electron microscope (SEM) images were used to study the surface morphology of coating. The grain size and amount of Fe₂O₃ particles present in composite coating were measured by X-ray diffraction pattern (XRD) and energy dispersive X-ray diffraction spectrometer (EDS), respectively.     

Effect of additive and current mode on surface morphology of palladium films from a non-aqueous deep eutectic solution (DES)

Electrodeposition of palladium from a non-aqueous electrolyte solution [choline chloride/urea/palladium(II)chloride] has been carried out by direct and pulse current electroplating. In this study, the influence of an organic additive (nicotinic acid amide), current mode (direct current or pulse current deposition) and hydrodynamic on the surface morphology of electroplated palladium films was investigated. In order to determine the surface morphology and thickness of the electrodeposited palladium layers, a scanning electron microscope and an energy dispersive X-ray fluorescence spectroscope were used. In addition, the cell voltage during the different electrodeposition experiments was recorded and analysed. The experimental results showed that the surface morphology of the palladium deposits could be remarkably affected either by addition of the additive or by applying pulse current. Pulse plating and the selected inhibitor mutually interfere with each other, causing changes in the microstructure of the palladium deposits (e.g. smoothening or forming of micro-cracks). It was possible to optimise the palladium deposit quality by applying pulse current or by addition of the appropriate inhibitor.     

Composition controlling of Co-Ni and Fe-Co alloys using pulse-reverse electroplating through means of experimental strategies

The optimal plating settings in the pulse-reverse electroplating mode for the non-anomalous plating of Co-Ni deposits (i.e., the metal composition of deposits is equal to that of the plating solutions) from chloride solutions were approached by using experimental strategies including fractional factorial design (FFD), path of steepest ascent and central composite design (CCD) coupled with the response surface methodology (RSM). The potentials and time period of pulse-plating were the key factors affecting the composition of Co-Ni deposits in the FFD study. The two variables were the path of the steepest ascent investigation to approach the optimal conditions for non-anomalous plating of Co-Ni deposits. The effects of pulse-plating potential and pulse-plating time on the compositions of Co-Ni deposits were further examined using a regression model in the CCD study.The variable Ni contents of Co-Ni deposits are caused by metal hydroxide on the deposit surface. After anodic dissolution process, the increasing pulse-plating time and lower pulse-plating potential can remove metal hydroxide and improve Ni ion deposition ratio on the fresh deposit.All Fe-Co deposits were equal to the composition metal ratio of plating bath while pulse-reverse-plating potential included the anodic dissolution process.     

Influence of nickel ions for electroless Ni–P plating on polyester fabric

Properties of electroless Ni–P plated polyester fabric mainly depend on the plating bath constituents/conditions. The effects of NiSO₄ concentration of the plating bath on the deposition rate, phosphorus content, surface morphology, and crystal structure of the electroless Ni–P plated polyester fabric were investigated. The study revealed that phosphorus content in the deposits decreased at higher NiSO₄ concentration. SEM micrographs showed that nodule size of the Ni–P deposits increased. All the Ni–P deposits had an amorphous structure. The electromagnetic interference (EMI) shielding effectiveness (SE) of electroless Ni–P plated polyester fabric was evaluated. With the rise of nickel ion in the solution, the EMI SE of the Ni–P plated polyester fabric increased.     

装饰性镀铬故障处理

介绍了装饰性镀铬最常见的质量故障:均镀能力差、边角易烧焦、铬层暗灰色、花斑、蓝膜、雾状、麻面和粗糙等。分析讨论了故障产生的原因及其处理方法,并提出了加强现场管理,以控制和减少故障发生的措施。     

Chromium electrodeposition from [BMIm][BF<Subscript>4</Subscript>] ionic liquid

The electrodeposition of black chromium coatings from ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate with chromium chloride, and the chemical composition of the deposits are discussed in this article. The UV–Vis spectra recorded for chromium(III) species in 1-butyl-3-methylimidazolium tetrafluoroborate suggest that along with the chromium(III) complexes containing three ligands, there are some amounts of chromium species containing four ligands in the bath employed. The cathodic process of chromium electrodeposition in the employed ionic liquid is complicated by the electrochemical reduction of water molecules, which is followed by chemical disintegration of tetrafluoroborate ions. The surface morphology of black chromium films deposited potentiostatically (–1.5 to −2.0 V) at 85 °C shows nodules and microcracks increasing in size with cathodic potential. Analysis of the X-ray photoelectron spectra recorded from surface to depth of the deposit has shown that the black oxide-rich chromium coating consists of chromium in both oxide and metallic states with small impurities of other elements (fluorine, boron, carbon and nitrogen) and the surface is covered with a thin layer of organic substances. The results of this study show that 1-butyl-3-methylimidazolium tetrafluoroborate may be considered as a promising substitute of toxic Cr(VI) baths for black chromium plating.     

Preparation of Pt–Co alloy catalysts by electrodeposition for oxygen reduction in PEMFC

Direct current (DC) and pulse current (PC) electrodeposition of Pt–Co alloy onto pretreated electrodes has been conducted to fabricate catalyst electrodes for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC). The effect of plating mode and pulse plating parameters on the Pt–Co alloy catalyst structure, composition and electroactivity for the ORR in PEMFC has been investigated. The electrodeposited Pt–Co alloy catalyst indicates higher electrocatalytic activity towards the ORR than the electrodeposited Pt catalyst. The activity of the electrodeposited Pt–Co catalysts is further improved by applying the current in a pulse waveform pattern. The electrodeposition mode and the pulse plating parameters do not have the significant effect on the Pt:Co composition of deposited catalysts, but show the substantial effect on the deposit structures produced. The Pt–Co catalysts prepared by PC electrodeposition have finer structures and contain smaller Pt–Co catalyst particles compared to that produced by DC electrodeposition. By varying the Pt concentration in deposition solution, the Pt:Co composition of the electrodeposited catalyst that exhibits the highest activity is found. The Pt–Co alloy catalyst with the Pt:Co composition of 82:18 obtained at the charge density of 2 C cm⁻², the pulse current density of 200 mA cm⁻², 5% duty cycle and 1 Hz was found to yield the best electrocatalytic activity towards the ORR in PEMFC.     

Electrochemical studies of zinc–cobalt alloy coatings deposited from alkaline baths containing glycine as complexing agent

Co-deposition of Zn–Co alloy coatings that were electrodeposited from weakly alkaline glycine solutions has been studied by cyclic voltammetry. Scanning electron microscopy (SEM), energy depressive spectroscopy (EDS), and X-ray diffraction (XRD) analyses were used to study surface morphology, chemical composition, and phase structure of the coatings. Corrosion behavior of the coatings was also studied using potentiodynamic polarization tests in 3.5 wt% NaCl solution. Cyclic voltammetry results showed that in Zn–Co deposition from an alkaline bath in the presence of glycine, cobalt deposited at a potential near to that of zinc together with successful co-deposition of Co and Zn. It was also shown that reduction–oxidation (redox) reactions of Zn–Co alloy deposits were quasi-reversible and resulted in deviation of electrodeposited alloys from the equilibrium phase diagrams. The corrosion resistance of the deposits was also highly influenced by the composition and morphology of the coatings. Overall, Zn–Co deposit containing 0.89 wt% Co showed that the highest corrosion resistance among the coatings that was due to its single phase structure and fine morphology.     

Synthesis,characterization, and infrared-emissivity study of Ni–P–CB nanocomposite coatings by electroless process

The Ni–P–CB (carbon black) nanocomposite coatings have been successfully deposited on an ABS plastic matrix via electroless plating process. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectrometry techniques were employed to examine the surface morphology and structure of the as-plated coating. Energy dispersive spectroscopy (EDS) was adopted to obtain the component analysis of the Ni–P–CB composite coating, and the infrared emissivity of the coating was determined by the IRE-I Infrared Emissometer. SEM and XRD results indicated that the nanoparticles were dispersed homogeneously in the Ni–P coating; the result of EDS showed that the increased rate of CB content is in correspondence with its concentration. In the case that CB concentration is lower than 4 g/L, the increase rate is sharp, whereas when the concentration is higher than 4 g/L, the increase rate is reduced significantly. Furthermore, study of infrared emissivity shows that the nanocomposite coatings possessed low emissivity value. A comparison of the infrared emissivity dependence on surface resistivity obtained from the analysis of the experimental results and those calculated using the Hagen–Rubens relation indicates that the Hagen–Rubens relation is good for modeling the infrared emissivity of the Ni–P–CB nanocomposite coatings.     

Electroless deposition of ternary Ni–P alloy coatings containing tungsten or nano-scattered alumina composite on steel

The performance of ternary electroless deposited Ni–P–W and Ni–P–alumina composite coatings on low carbon steel substrates was studied. The effect of experimental parameters, such as temperature, pH, nickel sulfate concentration, sodium hypophosphite concentration, sodium citrate concentration, and deposition time on the deposition rate were investigated. The coating brightness, coherence, and uniform surface distribution were improved due to addition of W and alumina. The coating performance was evaluated based on the wear-resistance, micro-hardness, and corrosion resistance. The Ni–P–W ternary alloy coatings showed the highest micro hardness, wear-resistance, brightness, and corrosion resistance. The improvement in the performance of Ni–P–W coatings can be explained by the formation of a tungsten phosphide phase.     

铅板无氰仿金镀工艺研究

用扫描电镜和能谱分析方法,研究了铅板上仿金镀层组成颜色及表面形貌,确定了铅板上仿金电镀的工艺流程及最佳工艺参数.结果表明,以光亮镀镍打底,仿金镀的Jκ=1.2 A/dm2;pH=8.5～9.3;θ=20～35℃;t=1～4 min的条件下,能够获得仿金色镀层,且镀层表面平整,结晶细致,无裂痕、孔隙,镀层质量较好.     

Electro-deposition and characterizations of nickel coatings on the carbon–polythene composite

Nickel coating on the carbon–polythene composite plate was prepared by electrodeposition in a nickel sulfate solution in this work. The morphology and cross-sectional microstructure of the nickel coating were examined by scanning electron microscope (SEM) and optical microscope (OM), respectively. The influence of bath temperature on the nickel deposition rate was investigated experimentally. The adhesion between the coating and the substrate was evaluated by the pull-off test. The corrosion behavior of the coating in an aqueous solution of NaCl was studied by electrochemical methods. The results showed that the nickel electrodeposition rate could reach up to 0.68 μm min⁻¹ on average under conditions of cathodic current density of 20 mA cm⁻² and bath temperature of 60 °C. It was confirmed that increasing the bath temperature up to 50 °C had a positive effect on the nickel deposit rate, while an adverse effect was observed beyond 60 °C. The adhesion strength between the nickel coating and the substrate can be more than 2.3 MPa. The corrosion potential of the bright coating in the NaCl solution was more positive than that of the dull coating, and the anodic dissolution rate of the bright coating was also far lower at the same polarization potential compared with the dull coating.