Influence of deposition temperature and heat treatment on the performance of electroless Ni-B films

Electroless nickel-boron (Ni-B) was synthesized on mild steel or copper surface. The deposition of thin electroless Ni-B films using an acidic bath having nickel chloride as a source of nickel and dimethylamine borane (DMAB) as a reducing agent and operated at low temperature has been investigated in this paper. The effect of the plating time and temperature on the quality of Ni-B coatings was estimated. The results revealed that the plating rate decreases with increasing plating time and increases with increasing plating temperatures. The boron (B) content of the electroless Ni-B layer increased with increasing temperature. The resulting surfaces were examined and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). XRD analysis was performed to investigate structural modifications. Microhardness, corrosion and oxidation resistance of electroless as-plated and heat-treated Ni-B coatings, were evaluated. The effect of heat treatment temperature on the phase structure and microhardness of Ni-B coated at different temperatures was discussed. XRD patterns reveal that electroless Ni-B coatings deposited at 60 and 80 °C are amorphous in as-plated condition and undergo phase transformation to crystalline nickel and nickel borides upon heat-treatment. Heat treatment achieved significant improvement in the microhardness and corrosion resistance due to the formation of the Ni-B compound phases (Ni₃B).     

Coating different thickness nickel-boron nanolayers onto boron carbide particles

This work is focused on electroless coating of nickel-boron (Ni-B) onto boron carbide (B₄C) particles. Using NiSO₄ as Ni²⁺ source, SnCl₂ as sensitizing agent, PdCl₂ as activation agent, and NaBH₄ as reducing agent, Ni-B nanolayers of different thicknesses have been successfully coated onto the B₄C particles. The B₄C particles are around 2 μm in size and the Ni-B coating thickness can be adjusted by changing the Ni²⁺:B₄C ratio. For the targeted 1 nm Ni-B thickness, the layer is discontinuous. When the targeted Ni-B layer increases to 5 nm, the coating layer becomes continuous and completely covers the B₄C particle surfaces. When the targeted Ni-B coating thickness increases to 10 nm or higher, Ni-B nodules start to form with the mesh-like structures between the Ni-B nodules. The Ni-B nodule size increases with the Ni-B layer thickness. EDS results show the presence of oxygen in the Ni-B coating; oxygen content decreases as the Ni-B coating thickness increases. XPS confirms that B₂O₃ forms in the coating and the Ni:B ratio decreases with the Ni-B layer thickness. Ni-B electroless coating processes and morphological changes on the B₄C particle surfaces with different Ni-B coating thickness are analyzed.     

TiO2 nanotube-supported amorphous Ni-B electrode for electrocatalytic oxidation of methanol

Amorphous Ni-B/TiO₂ electrodes were successfully prepared by electroless plating. Highly ordered TiO₂ nanotube arrays fabricated by anodic oxidation were employed as substrate and loaded with Ni-B alloy by electroless plating. The phase formation, microstructures and catalytic activity of electrodes were investigated by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and electrochemistry analyzer, respectively. The results show that Ni-B/TiO₂ electrodes with an average particle size of 200 nm present a typical amorphous structure of Ni and B, and have high catalytic activity for methanol electrooxidation in alkaline medium. The peak current density in cyclic voltammetry (CV) curves reaches 360 mA cm⁻² in the solution with 0.5 mol L⁻¹ methanol, much higher than that of Ni-B/Ti electrode. With the methanol concentration increasing to 1.5 mol L⁻¹, the peak current density increases to 488 mA cm⁻², after which it remains almost constant. The Ni-B/TiO₂ electrodes are relatively stable according to catalytic lifetime test; the peak current density remains 72.1% of the original value after 1300 times cycles. The amorphous Ni-B/TiO₂ electrode should be a promising candidate for direct methanol fuel cell.     

A study of corrosion resistance and formation characteristics of electroless Ni-P alloy coatings on Al18B4O33w/6061 Al composite with a simple surface pre-treatment

Ni-P alloy coatings were successfully deposited on Al₁₈B₄O₃₃w/6061 Al composite by electroless deposition. A simple surface pre-treatment method prior to the coating process was used for the first time. The coatings were characterized by SEM/EDX, TEM and electrochemical methods. It was found that the pre-treatment prior to the coatings had an important effect on the electroless plating, which offered an active surface for the electroless deposition, resulting in the Ni-P coatings being uniformly formed on the substrate and providing the protection for the composite substrate.     

Effect of tartrate salt concentration on the morphological characteristics and composition of Cu-Zn electroless plating on zamak 5 zinc alloy

This work reports the characterization of brass coatings deposited by an electroless process on zamak-5 alloy substrate. The results show that an increase in the tartrate salt concentration in the brass electroless bath promotes an increase in the copper deposition rate. It was observed that, in coatings with less concentrations of the tartrate salt, the Cu/Zn atomic ratio is always less than one, with a slight increase across the coating thickness. In coatings prepared from solutions with greater tartrate salt concentration, Zn deposits at higher rates at the beginning of the deposition, however after certain thickness, the Cu/Zn atomic ratio was greater than one. This change in composition affects the bulk and surface morphology of the deposited coatings, which were analyzed using a Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) and showed strong metallic Zn and weak CuZn₅ (ε-phase) diffraction lines.     

Effects of NH4F on the deposition rate and buffering capability of electroless Ni-P plating solution

The deposition rate and buffering capability of alkaline electroless Ni-P plating solution containing ammonium fluoride (NH₄F) have been investigated. When the NH₄F concentration is below 10 g L^− 1, the deposition rate is improved with the addition of NH₄F, reaching the maximum value at 2 g L^− 1. The buffering capability of solutions is found to be improved with increasing NH₄F concentration. Due to the improvement of buffering capability, refined and compact Ni-P coatings with homogeneous elemental distribution of P have been achieved. Therefore, both the corrosion resistance and microhardness of Ni-P coatings are significantly improved. The mechanism of NH₄F improving the deposition rate and the buffering capability is discussed.     

Electrochemical characterisation of the porosity and corrosion resistance of electrochemically deposited metal coatings

Electrochemical techniques for the assessment of porosity in electrodeposited metal coatings are reviewed. The determination of porosity and corrosion, resistance is illustrated by electrochemical data from three coating/substrate systems namely: electroless nickel on aluminium and steel and immersed gold coatings on an electroless copper-plated ABS polymer. Nickel coatings were up to 24 μm thick while gold deposits had thickness between 75 and 190 nm. Tafel extrapolation and linear polarisation resistance methods were used to determine the corrosion rate of the coated substrates. The aluminium samples were tested in 5% w/v (0.85 mol dm^− 3) NaCl, while coated steel and ABS samples were immersed in 0.125 mol dm^− 3 H₂SO₄ and 0.1 mol dm^− 3 NaBH₄, respectively, at 295 K. Current vs. time curves and anodic polarisation behaviour have also been considered.     

Preparation and Properties of Electroless Ni-Cu-B Alloy Deposits

Two series of Ni-Cu-B deposits were prepared by electroless plating. The effects of the [Cu²⁺]/[Ni²⁺] molar ratio and concentration of KBH₄ in solution on the deposition rate, surface appearance, structure, composition, hardness, corrosion resistance and wettability have been studied. The high-B content deposits are amorphous and their structural change with annealing at different temperature results in changes of hardness of the deposits. For low-B content deposits, structures range from Ni-rich solid solution to Cu-rich solid solution with increasing (Cu²⁺]/[Ni²⁺] molar ratio; an intermediate solid solution is obtained near 0.024 (Cu²⁺]/[Ni²⁺] molar ratio. The corrosion resistance of the deposits is much better in basic media than acid, and their wettability is worse than Ni-B deposit and silver or gold wire.     

新型三元复合络合剂体系对AZ91D镁合金表面酸性化学镀Ni-P的影响

利用含新型三元复合络合剂的酸性化学镀镍液体系,在AZ91D镁合金表面通过化学镀制备Ni-P防护镀层。结果表明,镀层沉积速率随着镀液中三元复合络合剂浓度的变化而改变。利用X射线衍射（XRD）、扫描电子显微镜（SEM）和差热分析（DSC）对镀层结构、形貌以及热稳定性进行表征和分析。通过交流阻抗（EIS）和动电位扫描极化曲线对Ni-P镀层在3.5%NaCl溶液中的耐蚀性能进行评价。镀液中三元复合络合剂的浓度对Ni-P镀层的结构与形貌有显著影响。Ni-P镀层的热稳定性随着三元复合络合剂浓度的增加而降低。当镀液中三元复合络合剂浓度为0.035 mol/L时,所制备的Ni-P镀层致密、均一,在3.5%NaCl溶液中表现出良好的耐蚀性能。     

Deposition and corrosion resistance of electroless Ni-PCTFE-P nanocomposite coatings

The present work deals with the process of electroless deposition and electrochemical corrosion behavior of nickel-polychlorotrifluoroethylene-phosphorous (Ni-PCTFE-P) nanocomposite coatings. The process of autocatalytic-catalytic reduction of Ni in nickel sulfate and sodium hypophosphate solution with PCTFE suspended particles has been employed for the formation of the electroless Ni-PCTFE-P composite coatings. Surface morphology and composition of the composite coatings are characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) measurements and X-ray diffraction (XRD) analysis. Corrosion behavior of coatings is evaluated using open-circuit potential (E_OCP) measurements, electrochemical impedance spectroscopy (EIS) and polarization techniques in 3.5 wt.% NaCl solution. The study reveals significant shift in corrosion potential towards the noble direction, decrease in corrosion current density, increase in charge transfer resistance and decrease in double‐layer capacitance values with the incorporation of PCTFE particles in the Ni-P matrix. The significant improvement in corrosion resistance observed for Ni-PCTFE-P nanocomposite coatings (25.3 kΩ cm²) compared to Ni-P (16 kΩ cm²) could have resulted from the microstructural differences of pure Ni-P with Ni-PCTFE-P nanocomposite coatings.     

Investigation of electroless copper plating on polyurethane foam,as an initial step of open cell foam production process

Abstract

Coating of polymeric foams is known as a method for production of metallic foams, which produces foams with high volume of porosity and controllable pore size. In this research, this method was employed to produce open cell copper foam by use of polyurethane foam with an average pore size of 0.4?mm as the substrate. Since polyurethane foam as a non-conductive material is not able to be coated directly by electrolytic deposition, the substrate was initially metallised by electroless copper plating. In the electroless plating process, the effects of the main parameters such as bath chemical composition, solution pH and temperature on deposition rate and thickness of the coatings obtained were investigated. The results showed that the optimum condition of the process is obtained when CuSO₄ concentration in the deposition bath is 12?g?L^??1, pH is 13 and plating temperature range is 55–60°C.     

Ce 盐封孔对 SiCp/ Al 复合材料表面 Ni-P 镀层的影响

为提高SiCp/Al复合材料的耐腐蚀性能,先化学镀镍,再沉积稀土封孔,讨论了稀土溶液主盐Ce(NO3)3浓度和沉积时间对镍-稀土多层膜耐蚀性能的影响。结果表明:化学镀镍的SiCp/Al复合材料在室温下沉积稀土时,采用Ce(NO3)3含量1 g/L、成膜时间2 h的条件获得的多层膜耐蚀性最好,其腐蚀电位为-0.48mV,腐蚀电流密度为3.54×10-8A/cm2;稀土在膜层中以Ce的氧化物颗粒堆积状态存在,起到了封孔的作用;膜层中的镍磷合金呈多晶态,而稀土含量少,未能测出;稀土溶液浓度越高,沉积速度越快,而在相同浓度下,膜层厚度随着时间的延长而增加,越厚则膜层结合力越差。     

The effect of copper ion on microstructure,plating rate and anticorrosive performance of electroless Ni-P coating on AZ61 magnesium alloy

In this paper, the effects of copper ion addition on microstructure, composition, deposition rate and anticorrosive performance of electroless Ni-P coating on AZ61 magnesium alloy have been investigated. Deposits were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) techniques. The corrosion behavior of the deposits was studied by Open Circuit Potential (OCP) measurements and Electrochemical Impedance Spectroscopy (EIS) in 3.5 wt % NaCl. Moreover, the deposition rate of the coatings was determined by polarization tests. The results indicate that introduction of Cu²⁺ improves the characteristics and anticorrosion performance of Ni-P coating.     

不同纳米WS2含量Ni-P-Ti N-WS_(2)复合化学镀层的制备及其摩擦学性能EI北大核心CSCD

Ni-P-TiN化学复合镀层具有比Ni-P镀层更高的硬度和耐磨性,但其表面粗糙度大,与对偶件之间的摩擦因数高,应用潜力受到限制。通过在化学镀液中添加不同用量的纳米WS_(2)颗粒和固定用量的TiN颗粒,在低碳钢表面制备Ni-P-TiN-WS_(2)复合镀层。采用X射线能谱仪(EDS)、扫描电子显微镜(SEM)和X射线衍射仪(XRD)对镀层的化学成分(质量分数)、表面形貌及微观结构进行表征,并利用球盘式摩擦磨损试验机测试复合镀层的摩擦磨损性能。结果表明:纳米WS_(2)颗粒与纳米TiN颗粒的共沉积可使镀层表面更加致密、平整。随着镀液中纳米WS_(2)用量的增加,复合镀层的硬度先减小后增大,与氮化硅陶瓷球的摩擦因数则先升后降,磨损率显著下降,耐磨性增强。镀液中纳米WS_(2)粉末的用量为2.5 g/L时复合镀层的摩擦学性能最佳。纳米WS_(2)颗粒的加入及用量优化可显著改善复合镀层的综合性能,可为发展高耐磨低摩擦因数的先进涂层提供借鉴。     

High temperature friction and wear behaviour of Ni–P–Ag–Al2O3 hybrid nanocomposite coating

Abstract

Codeposition of silver and alumina particles has been performed within an Ni–P coating on carbon steel samples by electroless deposition to form an Ni–P–Ag–Al₂O₃ hybrid nanocomposite coating. The structure of heat treated coatings was evaluated by XRD analysis. Tribological properties of the coatings were investigated by a pin-on-disc test method using a 52100 steel pin as counter body at high temperature. A 3D optical profiler was employed to measure the wear rate of the deposits. Surface morphology, cross section and wear scars of the coatings were studied by using SEM equipped with EDS analysis. The results showed that tribological properties of Ni–P–Ag–Al₂O₃ hybrid coating are similar to Ni–P–Ag conventional composite coating. Moreover, friction coefficient and wear resistance of the hybrid coating are strongly influenced by self-lubricating silver thin layers formed between mating surfaces during high temperature sliding wear.     

Effects of cathodic electrodeposition parameters of cerium oxide film on the corrosion resistance of the 2024 Al alloy

Cerium oxide thin films obtained by cathodic electrodeposition on 2024 aluminium alloy have been studied. The coatings, obtained with electrochemical deposition, offer an effective corrosion protection and require a lower deposition time when compared to chemical conversion coatings. The coatings were obtained at room temperature by deposition from CeCl₃/H₂O₂ aqueous solutions and the influence of several parameters (CeCl₃ concentration, H₂O₂ concentration, deposition time, current intensity) on the corrosion resistance was studied. The composition, morphology and microstructure of the films have been characterized by SEM, XPS and AFM. The corrosion resistance was investigated through potentiodynamic tests in 3% NaCl solution.     

Electrodeposition and characterization of Zn-Mn alloy coatings obtained from a chloride-based acidic bath containing ammonium thiocyanate as an additive

The electrodeposition of Zn-Mn alloys was performed using a chloride-based acidic bath containing ammonium thiocyanate (NH₄SCN) as an additive. An electrochemical study using cyclic voltammetry (CV), performed for each of the metal ions (Zn(II) and Mn(II)), showed that neither metal ion forms complexes with NH₃, and that Mn(II) but not Zn(II) forms complexes with SCN⁻. The influence of NH₄SCN on the morphology, composition and crystallographic structure of the electrodeposited Zn-Mn alloys was studied using scanning electron microscopy (SEM), glow discharge spectroscopy (GDS) and X-ray diffraction (XRD). The results show that the presence of NH₄SCN in the solution induces an increase in the Mn content of the alloy, from 3% in the Zn-Mn alloy obtained in the absence of additive to 6.2% in the alloy obtained in the presence of additive. In addition, the presence of NH₄SCN favors the formation of coatings comprised of a mixture of ε-phase Zn-Mn(002) + α-phase Zn-Mn(111) alloys. These coatings were compact and smooth and exhibited a lower corrosion rate compared to the coatings obtained in the absence of NH₄SCN, which where comprised of a mixture of Zn, ε-phase Zn-Mn and α-phase Zn-Mn alloys.     

Experimental design of plasma spraying and laser treatment of hydroxyapatite coatings

Plasma spray process of hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HA) followed by laser treatment of obtained coatings were optimized by an advanced statistical planning of experiments. The full factorial design of 2⁴ experiments was used to find effects of four principal parameters, i.e. electric power, plasma forming gas composition, carrier gas flow rate and laser power density onto microstructure of hydroxyapatite (HA) coatings and powders and depth of laser melted zone. The SAS and Statgraphics commercial softwares have been applied to obtain the mathematical model of influence of process parameters onto experimental responses. The chosen responses were the fraction of HA crystal phase and two phases of its decomposition α-tricalcium phosphate (Ca₃(PO₄)₂, α-TCP), tetracalcium phosphate (Ca₄P₂O₉, TTCP) and, on the other hand, the depth of laser melted zone in the coating. The two most important factors influencing these responses are electric power supplied to torch, laser power density. Laser power density is very important for the depth of laser melted zone. The crystal phase content of powders and coatings was determined using X-ray diffraction (XRD) quantitative analysis. The morphologies of coatings surfaces, cross-sections were characterized using scanning electron microscope (SEM).     

PREPARATION AND ANALYSIS OF Ni-P-Zn ELECTROLESS DEPOSITION FROM ALKALT BATH

Electroless Ni-P-Zn alloys deposited from alkali bath were investigated in this paper. The deposition bath contained nickel sulfate, zinc chloride and hypophosphate. The process parameters, such as temperature, pH and zinc salt concentration were presented and discussed.The microstructure of the coatings was studied by XRD and SEM. The cathode glowing discharge characters of Ni-P-Zn depositions were studied with luminous Neon lamps. Electrodes deposited by electroless Ni-P alloys were apt to sputter during luminous working hours. Electroless Ni-P-Zn depositions improved the discharge characters of the electrodes.With the concentration of zinc in the deposition rising to 4wt%, electrode sputter was largely restrained. The thickness of the deposition also influenced the discharge characters of the electrode. To avoid electrode sputter, the concentration of zinc has to rise with the thickness of the depositions.     

Laser nanocrystallisation and corrosion behaviour of electroless Ni–W–P coating with high phosphorus content

This paper reports an investigation of microstructural characteristics in electroless Ni–3·9W–13·4P (wt.%) coating by laser nanocrystallisation using a quantitative X–ray diffraction (XRD) method and scanning electron microscopy (SEM) with energy dispersive X–ray spectroscopy (EDX). The corrosion resistance of the coatings before and after laser treatment has been evaluated in 0·5 M H₂SO₄ solution by potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) techniques. The results show that the laser treatment improves the corrosion resistance of the coatings. The corrosion mechanism has been studied and correlated to the microstructural characteristics including volume fraction of I_Ni3P/I_total, microstrain, and the crystallite size of the Ni and Ni₃P phases.