Ultrasonic-assisted Electroless Plating Research Articles

Synergistic enhancing effect of tungsten-copper coated graphite flakes and aluminum nitride nanoparticles on microstructure, mechanical and thermal properties of copper matrix composites

Thermal management materials with high thermal conductivity (TC), adjustable coefficient of thermal expansion (CTE) and excellent mechanical properties have promising applications in the electronic packaging and high-power density equipment fields. In this work, we have developed a novel strategy for tungsten-copper coated graphite flakes and aluminum nitride nanoparticles reinforced copper matrix composites (GFs(W–Cu)/AlN/Cu composites) fabricated by vacuum hot-pressing sintering. Herein, tungsten-copper coated graphite flakes (GFs(W–Cu)) were prepared by impregnation reduction and ultrasonic-assisted electroless plating, in which W–Cu coating improved interfacial bonding and realized metallurgical-physical synergy. Meanwhile, the AlN nanoparticles reinforced Cu flakes (AlN/Cu) were prepared by high energy ball milling, where AlN nanoparticles were evenly dispersed in the Cu matrix and played the role of pinning boundary and refining grain. Effects of nano-AlN with different volume fractions on the mechanical and thermal properties of GFs(W–Cu)/AlN/Cu composites were studied as well. As for the mechanical properties, the in-plane, through-plane flexural strength and tensile strength of GFs(W–Cu)/1.5AlN/Cu composite reached 276.7 ± 4.5, 390.6 ± 4.5 and 136.1 ± 3.0 MPa respectively, which increased by 96.8%, 283.7% and 120.7% than those of the GFs(W–Cu)/Cu composites. In terms of the thermal properties, the in-plane TC of GFs(W–Cu)/1.5AlN/Cu composite is 617.8 ± 12 Wm−1K−1, while the through-plane CTE ranging 25–200 °C is 4.9 ± 0.2 ppmK-1. In conclusion, the GFs(W–Cu)/AlN/Cu composites provide a huge potential for design and application in the thermal management materials.

Fabrication, mechanical and thermal properties of tungsten-copper coated graphite flakes reinforced copper matrix composites

Carbon materials reinforced copper matrix composites with excellent mechanical properties, high thermal conductivity (TC) and suitable coefficient of thermal expansion (CTE) are expected to meet the urgent need for the thermal management materials with structural stability and efficient heat dissipation in civil and military fields. In this work, the tungsten-copper (W-Cu) composite coating was deposited on the graphite flakes (GFs) by the impregnation-reduction and ultrasonic-assisted electroless plating. Meanwhile, the W-Cu coated GFs reinforced Cu matrix composites (GFs(W-Cu)/Cu) were also prepared by the vacuum hot-pressing sintering. Based on the microstructure and surface analysis, the interfacial bonding has changed from the simple mechanical connection to the mechanical-metallurgical synergy. As for the three-point bending and uniaxial tensile tests, the largest in-plane, through-plane flexural strength and tensile strength of the GFs(W-Cu)/Cu composite can achieve the values of 189.6 ± 3.8, 172.3 ± 4.2 and 91.9 ± 2.6 MPa, respectively. Among the GFs(W-Cu)/Cu composites, the ultrahigh in-plane TC and lowest through-plane CTE can reach 929.8 ± 5.0 Wm−1K−1 and 6.3 ± 0.2 ppmK−1 respectively, and the better thermal response rate can be 0.67 °C·s−1. In conclusion, an effective way to develop the structural and functional integrated carbon-based thermal management materials can be provided.

Fabrication, mechanical and thermal properties of copper coated graphite films reinforced copper matrix laminated composites via ultrasonic-assisted electroless plating and vacuum hot-pressing sintering

In the trend of integration of structure and function, novel thermal management materials are urgent to be developed owning good mechanical properties as well as excellent thermal properties. In this work, a complete and dense copper (Cu) coating with a thickness of 400 nm was deposited on the surfaces of graphite films (GFs) by ultrasonic-assisted electroless plating, which can improve the surface roughness of GFs and interfacial bonding between GFs and Cu foils. Cu-coated and uncoated GFs reinforced copper matrix laminated composites (noted as GFs(Cu)/Cu and GFs/Cu) were fabricated by optimized vacuum hot-pressing sintering. Based on the scratch test and microstructures of GFs(Cu) and GFs(Cu)/Cu composites, addition of Cu coating can improve the interfacial adhesion and element diffusion behavior, and intuitively explains the mechanical interlocking effect at the C–Cu interface. On basis of the nanoindentation mechanical properties across GFs(Cu)/Cu and GFs/Cu interfaces, the interfacial transition region with Cu coating of ~3 μm is three times of that without Cu coating. Flexural strength of 27.6 vol% GFs(Cu)/Cu laminated composite is 45.9 MPa, which is 56% higher than that of the corresponding GFs/Cu laminated composite. In-plane thermal conductivity (TC) and out-of-plane coefficient of thermal expansion (CTE) of 69.4 vol % GFs(Cu)/Cu laminated composite are 1177.8 W/m·K and −2.5 ppm/K respectively, which could be explained on the theoretical calculations and interfacial structures. In conclusion, the Cu coating on surfaces of GFs can generally improve the interfacial bonding, mechanical properties and thermal properties of GFs(Cu)/Cu laminated composites. It provides an effective way to develop novel structural and functional materials for thermal management.

Annealed high-phosphorus electroless Ni–P coatings for producing molds for precision glass molding

An annealed high-phosphorus electroless Ni–P coating was developed as the mold material for precision glass molding. The coating with a phosphorus content of 11.6 wt% was prepared on heat-resistant stainless steel via an intermittent ultrasonic-assisted electroless plating method. The effects of annealing temperature and heating rate on phase transformation, grain size variation, and mechanical properties were investigated. An annealing temperature of 600 °C with a heating rate of 5 °C/min was determined to be the optimal choice for heat treatment. Microgrooves were machined on the coating surface. After heat treatment, the increased hardness and modulus helped the microgrooves on the coating resist thermal deformation during the PGM process. The PV value decreased from 0.58 to 0.32 μm, and the surface roughness decreased from Sa 104.5 to Sa 62.6 nm. The mold produced by heat-treated coating was beneficial for improving the forming accuracy of precision glass molding.

The effect of heat treatment on Ni–B–Ce electroless coatings

ABSTRACTWe successfully obtained sonicated Ni–B–Ce coating on the surface of low carbon steel (Q235) through ultrasonic-assisted electroless plating with the deposition time of 60 minutes. The coatings were heat treated at 300, 500 and 800°C for 2 hours. The results showed the Ni–B–Ce coating changed from amorphous to crystallised and produced Ni3B and Ni2B phases after heat treatment. The addition of Ce changed the crystallisation temperatures of Ni–B–Ce coating after heat treatment to 562 and 692°C, which differed from those of Ni–B coating (298, 371 and 411°C). It also improved the activation energy to 156.85 and 214.11 kJ mol−1, which was much higher than those of Ni–B coating (32.23, 25.80 and 50.69 kJ mol−1). In addition, the 800°C annealed coatings showed notable improvement in hardness (1212 HV10) and corrosion properties (3.01 μA cm−2) which could be ascribed to the formation of Ni3B and Ni2B phases.

Sub-micron Co–Al2O3 composite powders prepared by room-temperature ultrasonic-assisted electroless plating

Sub-micron Co–Al2O3 composite powders were synthesized by ultrasonic-assisted electroless plating process at room temperature with a one-step activating method pretreatment. The effect of process parameters on plating rate, Co content, and the uniformity of cobalt layer was analyzed by transmission electron microscopy (TEM). The results show that as the initial pH values of plating bath increase, the plating rate increases. The plating rate declines as the load increases when the load of powders is less than 12 g·L−1, but increases when the load is greater than 12 g·L−1. The relative Co content of the Co–Al2O3 powder declines with the powder load increasing.

Catalytic role of surface pre-treatment of noble-metal-like tungsten carbide powder on electroless deposition of nickel

In this paper, tungsten carbide (WC) powder without noble-metal activation pretreatment has been coated with a thick layer of nickel (Ni) particles by ultrasonic-assisted electroless plating process at room temperature. The surface morphologies and composition of original WC powder, pretreated WC powder, Ni-coated WC powder prepared in different electroless nickel plating (ENP) baths and worn WC–Ni composite powder were analyzed by field emission scanning electron microscopy (FE-SEM) and energy dispersion spectrometry (EDS). The results suggest that the initial WC powder, whether or not pretreatment, are both able to initiate ENP successfully. WC itself is considered to have noble-metal-like catalytic performance to induce ENP under the system of sodium hypophosphite as reducing agent. The surface defects created by specific chemical activation pretreatment not only effectively enhance the catalytic ability, but also improve binding force of WC substrate and Ni coating. Moreover, the composition of ENP bath is a key factor which can regulate the growth rate and adsorption rate of Ni particles to maximize the catalytic activity of WC powder.

Ultrasonic-Assisted Electroless Plating of Silver Nanoparticles on Carbon Nanotubes

The purpose of this work was to study coating process of high dispersion silver particles on short single-walled carbon nanotubes (Short-SWCNTs) by electroless plating method with an assistance of ultrasonic agitation. The silver-coated carbon nanotubes were prepared and characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). The results revealed that silver particles with average sizes of 42±0.006 nm, 58±0.008 nm and 59±0.005 nm were achieved using ultrasonic-assisted electroless plating time of 15 min, 30 min and 45 min, respectively. The silver particle size was increased with increasing electroless plating time. Besides, the ultrasonic agitation promoted well dispersion and homogeneity of silver particles on the surface of carbon nanotubes.

A specific chemical activation pretreatment for electroless nickel plating on SiC ceramic powders

The electroless pretreatment of SiC ceramic powders through a specific chemical activation pretreatment method and room temperature ultrasonic auxiliary chemical deposition method can result in Ni layers on the surface of SiC ceramic powder. The growth mechanism of Ni layers and the surface morphologies and composition of initial SiC powders, pretreated SiC powders, and Ni-coated SiC powders were analyzed by field emission scanning electron microscopy (FE-SEM) and energy dispersion spectrometry (EDS). The results show that the uniformly Ni-coated SiC composite powders are successfully synthesized without conventional sensitization and activation steps by ultrasonic-assisted electroless plating at room temperature. The Ni layers on the powders have cell structures with dense uniform distribution. The growth process of Ni is as follows: the reactants in the chemical deposition solution absorb near the surface defects of SiC powder and the particles of Ni stick to the nucleation of surface defects of SiC powder through redox reaction. The Ni nucleus grows in three-dimensional direction to form cellular ‘Ni’ particles that accumulate into a film. On the surface of the Ni layer film, the Ni layer grows by superposition type.

PREPARATION OF ULTRAFINE W–Cu COMPOSITE POWDER USING ULTRASONIC-ASSISTED ELECTROLESS PLATING

W – Cu ultrafine/nanocomposite powders have high sintering activity, so ultrafine/nanotechnology of W – Cu composite powders is one of the main methods to obtain fully dense, high-performance W – Cu composite materials. Cu -coated ultrafine W composite powders were synthesized by ultrasonic-assisted electroless plating process with non-noble metal activation pretreatment at room temperature in this paper. The growth mechanism of Cu layers and surface morphologies and composition of initial ultrafine W powders, pretreated W powders and Cu -coated W powders were analyzed by field emission scanning electron microscopy (FE-SEM), and energy dispersion spectrometry (EDS). The results show that the uniformly Cu coated W composite powder is successfully synthesized without conventional sensitization and activation steps by ultrasonic-assisted electroless plating at room temperature. The Cu layers on the ultrafine W powders had cell structure with dense, uniform distribution. The growth mechanism of Cu layers appears as follows: the surfaces of pretreated W powders appear linear-like and lamellar-like surface defects which act as activated sites. The reactants in the plating solution were adsorbed on catalytic activity surfaces of powders and happened oxidation–reduction reaction. The growth and aggregation mechanisms of Cu particles after nucleation are stripy Cu -cells grew up, bend, bifurcated, and aggregated, then wounding into a cellular structure, like "wrapping wool clusters" in the life. Finally, Cu cells grow up and merge into a layer.

Electrocatalytic Oxidation of Glucose on Highly Dispersed Ni-B/Nanoporous Cu Amorphous Alloy Electrode

通过酸腐蚀去合金法处理热扩散制备的铜基表面铜锌合金得到纳米多孔铜（NPC）材料．以NPC为载体，采用超声辅助化学镀制备Ni．B／NPC合金电极．x射线衍射（XRD）和扫描电镜（SEM）表明Ni—B／NPC电极呈现由高分散纳米颗粒组成的非晶态结构．计时电流法（cA）结果表明化学镀5min制备的Ni．B／NPC电极具有最大的电化学活性表面积（EASA）．循环伏安法（cv）结果表明，与块状镍电极相比，碱性介质中在Ni—B／NPC电极上葡萄糖起始氧化电位负移39mV，氧化峰电流提高了18．9倍．采用线性扫描伏安法（LSV）、CA和电化学阻抗谱（EIS）N定Ni—B／NPC电极对葡萄糖电催化氧化的电子转移系数㈣、电催化氧化反应速率常数（∞和葡萄糖的扩散系数（D）等动力学参数．结果表明高分散Ni．B／NPC非晶态合金电极对碱性介质中葡萄糖的氧化具有较高的电催化活性和稳定性．

Preparation of nickel-coated tungsten carbide powders by room temperature ultrasonic-assisted electroless plating

In this paper nickel (Ni)-coated tungsten carbide (WC) composite powders have been synthesized by ultrasonic-assisted electroless plating with a simplified pretreatment at room temperature as the conventional sensitization and activation steps have not been employed. The growth mechanism of Ni layers and surface morphologies and composition of initial WC powders, pretreated WC powders and Ni-coated WC powders were analyzed by field emission scanning electron microscopy, and energy dispersion spectrometry. The results shows that uniform Ni-coated WC composite powders were successfully synthesized without conventional sensitization and activation steps by ultrasonic-assisted electroless plating at room temperature. The growth mechanism of Ni layers appears as follows: the surfaces of pretreated WC powders appear step-like defects which act as activated sites. Nucleation and the growth of nickel grains take place on the activated sites of pretreated WC powder, and the process repeats continuously on the lath particles with reticulate structure on the as-coated surfaces of previously deposited Ni-cells, finally Ni cells grow up and merge into a layer.

Preparation and characterization of Ni-coated Cr 3C 2 powder by room temperature ultrasonic-assisted electroless plating

Ni-coated Cr 3C 2 powder was prepared by ultrasonic-assisted electroless plating process without conventional sensitization and activation treatments at room temperature. The growth mechanism of Ni layers and the effects of Cr 3C 2 powder concentration on plating rate and coating quality were studied. Surface morphologies and composition of initial Cr 3C 2 powder, pre-treatment Cr 3C 2 powder and Ni-coated Cr 3C 2 powder were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that the Ni layers on the Cr 3C 2 powder had cell structure with dense and uniform distribution. The growth mechanism of Ni layers appears as follows: the pretreated surfaces of Cr 3C 2 powder act as activated sites, nucleation and the growth of nickel grains take place on the powder surfaces, and the process repeats continuously on the lath particles with reticulate structure on the as-coated surfaces of previously deposited Ni-cells, finally Ni cells grow up and merge into a layer. With the increase of Cr 3C 2 powder concentration, the plating time becomes shorter accordingly and the optimal powder concentration is 40 g L −1.