Assisted Electroless Plating Research Articles

Synthesize and characterization of silver coated Ti powders from waste titanium chips by mechanical milling assisted electroless plating method

This study used an electroless silver (Ag) coating method on Ti powders obtained from waste turnings using mechanical milling, a recycling technique. Various parameters of Ag source and reducing agent ratios were utilized in the Ag coating processes. The results demonstrated that increasing the silver source and reducing agent ratios resulted in a more homogeneous and thicker Ag coating layer on Ti powders. The rise in the reduced silver ratio resulted in an increase in crystallite size compared to untreated particles, which was attributed to the reduction of residual dislocations in Ti through the presence of Ag. The amount of silver on silver-coated Ti powders ranged from 12.49 wt% to 24.4 wt%. Furthermore, an increase in the silver ratio significantly enhanced the oxidation resistance properties. The mass change with oxidation obtained from TGA analysis reduced from 26.31 wt% to 14.88 wt% with increasing silver coating layer on Ti powders.

Low-cost and eco-friendly fluidized bed hydrogen reduction assisted electroless plating to synthesize Ni-coated graphite

Electroless plating is the main method for preparing metal-coated composite powders, such as Ni-coated graphite powders with wide applications in electromagnetic shielding materials, sealing coating, and electrocatalysis. However, the issues of uniform and dense coating during synthesis are hindering its practical implementation. Incorporating noble metals, such as Pd, to activate powders is a typical technique to prepare an electroless Ni coating. However, noble metal utilization is hindered by issues such as high costs and substantial wastewater. Herein, a novel low-cost and eco-friendly activation method based on fluidized bed hydrogen reduction is designed to prepare densely coated Ni@irregular graphite particles (Ni@IGP) using a low Ni content. This method can be used to construct a uniform and dense Ni coating for composite powders without acid alkali treatment and use of precious metals during the overall manufacturing process. Results demonstrated that the Ni@IGP particle obtained through this approach have good electrical conductivity and ferromagnetic properties. In addition, the uniformity and integrity of the Ni plating were adjusted, and the dense coating of graphite at a low Ni content of 35 wt% was effectively achieved. This new activation method sheds light on the field of electroless Ni plating on powders.

Supercritical carbon dioxide-assisted gold metallization of 3D-printed structure and the tensile strength

Gold metallization of 3D printed polymer structures was conducted by a supercritical carbon dioxide (sc-CO2) assisted electroless plating process. Precursor of the Pd catalyst utilized in this study was palladium bis-hexafluoroacetylacetonate for the high solubility in sc-CO2. A Ni–P layer was first formed on the catalyzed polymer structure as a sacrificial layer for the sequential gold deposition. Electrical resistance of the gold metallized 3D printed structure was 0.15 Ω and slightly increased to 0.18 Ω after a tape adhesion test. The fracture strength was 47.6 MPa for the sample with 45 min of the gold deposition time.Graphical abstract

Platinum Metallization of Polyethylene Terephthalate by Supercritical Carbon Dioxide Catalyzation and the Tensile Fracture Strength

Polyethylene terephthalate (PET) is known to be highly inert, and this makes it difficult to be metallized. In addition, Pt electroless plating is rarely reported in the metallization of polymers. In this study, the metallization of biocompatible Pt metal is realized by supercritical CO2 (sc-CO2)-assisted electroless plating. The catalyst precursor used in the sc-CO2 catalyzation step is an organometallic compound, palladium (II) acetylacetonate (Pd(acac)2). The electrical resistance is evaluated, and a tape adhesion test is utilized to demonstrate intactness of the Pt layer on the PET film. The electrical resistance of the Pt/PET with 60 min of the Pt deposition time remains at a low level of 1.09 Ω after the adhesion test, revealing positive effects of the sc-CO2 catalyzation step. A tensile test is conducted to evaluate the mechanical strength of the Pt/PET. In-situ electrical resistances of the specimen are monitored during the tensile test. The fracture strength is determined from the stress value when the short circuit occurred. The fracture strength is 33.9 MPa for a specimen with 30 min of the Pt deposition time. As the Pt deposition time increases to 45 min and 60 min, the fracture strengths reach 52.3 MPa and 65.9 MPa, respectively. The promoted fracture strength and the decent electrical conductivity demonstrate the advantages toward biomedical devices.

The wear and arc erosion behavior of novel copper based functionally graded electrical contact materials fabricated by hot pressing assisted electroless plating

In this study, hot pressing was used to fabricate the novel copper based functionally graded electrical contact materials synthesized by silver, nickel and chrome plated copper core particles. For the fabrication of functionally graded materials (FGMs) by hot-pressing; pure copper, two and three layered metallic powders were used in the lower, middle and upper layer, respectively. The wear and arc-erosion performances of the developed materials increased from 3 to 10 times as compared to that of pure copper. Wear tests showed that the abrasive wear mechanism was dominant for the FGMs including electroless nickel and chromium coating layer. The highest specific wear rate (SWR) value was found in Cuf-Ag′ (4.9 × 10−4 mm3/Nm) materials under the load of 20 N while the lowest SWR value belongs to Cuf-Ag-Ni′ (2.3 × 10−4 mm3/Nm) materials under the load of 10 N. While severely melted and deformed regions are dominant on arc erosion surfaces of pure copper and copper-silver containing contacts, flatter and relatively less melted regions were detected on the surfaces of FGMs containing nickel and chromium. The arc-erosion loss values (cm3 × 10−4) measured for FGM1 sample were 0.75 and 0.70, 0.99 and 0.88, 1.21 and 1.04 at 3000 cycles under the current of 5 A, 10 A and 15 A in fixed and moving contacts, respectively.

Metallization of 3D-printed polymer structures via supercritical carbon dioxide-assisted electroless plating

3D-printed polymer structures were successfully metalized by a supercritical carbon dioxide (scCO2)-assisted electroless plating process. ScCO2 was used as the solvent in the catalyzation step, and the source of the catalyst was palladium bis-hexafluoroacetylacetonate. Ni–P coatings were deposited on surfaces of the catalyzed polymer structure with a commercially available solution. Electrical resistance of the Ni–P metallized polymer structure was measured, and the adhesion of the Ni–P coating on the polymer structure was evaluated by a tape adhesion test. The electrical resistance was 0.03 Ω and maintained at a low level of 0.04 Ω after the tape adhesion test.

Preparation of micron–sized polystyrene/silver core–shell microspheres by ultrasonic assisted electroless plating

In the study, PS/Ag composite microspheres with polystyrene (PS) core and silver shell were synthesized by ultrasonic electroless plating. The samples were characterized by SEM, FTIR and XRD. The effects of times of sensitization and silver plating, mass ratio of AgNO3 to PS microspheres and stirring method on the preparation and dispersion of PS/Ag microspheres were studied. The results show that the more times of sensitization and silver plating, the more uniform the silver deposition on the surface of microspheres. When the mass ratio of AgNO3 to PS microspheres is 2: 1, it can promote the uniform coating of silver shell and reduce the content of free silver. Ultrasonic assisted electroless plating for 10 min can prevent PS/Ag microspheres from agglomerating and improve the speed of electroless plating. The thickness of the silver shell on the surface of the PS microsphere is about 200 nm.

Preparation of NiP-WC Composite Coatings by Ultrasonically Assisted Electroless Plating and Their Characterization

Preparation of NiP-WC Composite Coatings by Ultrasonically Assisted Electroless Plating and Their Characterization

Preparation and characterization of Ni-Cu dual coated ZTA particles by ionic liquid-assisted electroless plating as reinforcement of metal-based composites

An ionic liquid assisted electroless plating is adopted to prepare continuous and dense Ni-Cu dual coatings on the surface of ZTA particles. The effects of l-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) additive, NiSO4 and CuSO4 concentrations on the surface morphologies, coating thickness, and element content of Ni-Cu dual coated ZrO2-toughened Al2O3 (ZTA@Ni-Cu) particles have been characterized systematically. Results show that with incremental addition of [bmim]BF4, suspended Ni-Cu particles in plating bath can be diminished but the incubation period and plating time of Ni-Cu coatings are prolonged significantly. The addition of 20 g·L−1 [bmim]BF4 is optimum for the preparation of uniform and compact ZTA@Ni-Cu particles. Besides, the thickness of Ni-Cu coating is about 20–30 μm and the Cu element content can be controlled in the range of 14.10–60.76 at.% through adjusting Cu(II) ions concentration. Furthermore, the possible reactions and deposition sequences for the preparation of Ni-Cu coatings on ZTA surfaces are analyzed and an empirical model of the deposition process assisted with [bmim]BF4 additive is also proposed to expound the function mechanism of [bmim]BF4 additive and the formation process of Ni-Cu coatings on ZTA surfaces.

The use of surfactants and supercritical CO2 assisted processes in the electroless nickel plating of printed circuit board with blind via

With the high density and high precision requirement of electronic products, printed circuit boards (PCBs) are also facing the evolution into multilayer boards. Electroless nickel immersion gold (ENIG) is a process that is widely used in the surface treatment of PCBs. As a barrier layer, nickel plating is required even in the blind via of PCB to improve its corrosion resistance for further plating processes. In this study, different surfactants, mainly anionic surfactant, Sodium Dodecyl Sulfate (SDS) and cationic surfactant, Cetyl Trimethyl Ammonium Bromide (CTAB), are used to explore their possible effects on this electroless process. It is found that SDS improves the deposition rate in blind via plating and coating's surface roughness. The surfactants are also effective in increasing the corrosion resistance of the prepared coating. Furthermore, different plating processes, i.e. supercritical carbon dioxide (Sc-CO2) assisted electroless plating and post supercritical carbon dioxide assisted electroless plating, are investigated and compared with the conventional process. It is obtained that Sc-CO2 assisted plating has the best improvement in blind via deposition rate and better coating's corrosion resistance. The result is indebted to the fact that the bath mixed with Sc-CO2 has low surface tension of gas and high mass transfusion of liquid. This nature effectively increases the deposition rate of coating in the blind via, and also makes the surface of the coating smoother and more uniform. To further explore whether high temperature affects the corrosion resistance of the coating when it passes through the reflow oven in surface mount technology (SMT) soldering operations of PCB, the coating is annealed at different elevated temperatures up to 400 °C. The experimental results found that annealing enables the grain refinement of the plated layer, thereby enhances the corrosion resistance of the plated layer.

Corrosion‐Resistant Superhydrophobic Coatings on Mg Alloy Surfaces Inspired by Lotus Seedpod

Superhydrophobic surfaces are widely found in nature, inspiring the development of excellent antiwater surfaces with barrier coatings isolating the underlying materials from the external environment. Here, the naturally occurring superhydrophobicity of lotus seedpod surfaces is reported. Protective coatings that mimic the lotus seedpod are fabricated on AZ91D Mg alloy surfaces with the synergistic effect of robust superhydrophobicity and durable corrosion resistance. The predesigned titanium dioxide films are coated on AZ91D by an in situ hydrothermal synthesis technique. Through sonication assisted electroless plating combined with a self‐assembling method, the densely packed Cu‐thiolate layers are uniformly plated with robust adhesion on the Mg alloy substrate, which function as a superhydrophobic barrier that can hold back the transport of water and corrosive ions contained such as Cl−. Notably, the two extreme wetting behaviors (superhydrophilicity and superhydrophobicity) as well as corrosion resistance and improved corrosion resistance can be easily controlled by removal of the hydrophobic materials (n‐dodecanethiol) at elevated temperature (350 °C) and modifying them at room temperature for 18 cycles, indicative of exceptional adhesion between the superhydrophobic coating and the underlying AZ91D Mg alloy.

Silk–Pt composite integration by supercritical carbon dioxide assisted electroless plating for medical devices application

This study successfully integrated flexible silk textiles and highly conductive platinum together by a supercritical CO2-assisted electroless plating process to achieve the materials for wearable medical devices. Pt and silk textiles were chosen for the composite material due to the request of high biocompatibility in the applications. Supercritical CO2 was introduced to the catalyzation step in the electroless plating process to promote the catalyst deposition. Surface morphology, composition, crystal structure, electrical resistance and biocompatibility assessments were evaluated. Coverage of the Pt layer increased as a function of the plating time. The thickness reached 0.91μm when 200min of the plating time was used. The lowest resistance at 86mΩ was obtained when the plating time was extended to 160min. The Pt ion releasing rate in the r-type simulated body fluid was negligible when comparing with the daily input and output of Pt in human body.

Green Fabrication of Ag Coated Polyacrylonitrile Nanofibrous Composite Membrane with High Catalytic Efficiency.

Ag-coated polyacrylonitrile (PAN) nanofibers have been prepared by a novel, facile and green way that combined electrospinning technique and poly(dopamine)-assisted electroless plating method. Poly(dopamine) (PDOP) was formed by oxidation polymerization of dopamine on the surface of PAN nanofibers to promote the electroless plating of silver. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy and energy dispersive X-ray spectroscopy (EDS) were used to characterize the morphology and structure of Ag/PDOP/PAN nanofibrous composite mem- brane and Ultraviolet-visible (UV-vis) Spectroscopy was used to investigate its catalytic performance. The results indicated that silver clusters composed of face-centred cubic crystal Ag with average crystallite size of about 18 nm were well distributed on the surface of dopamine-modified electrospun PAN nanofibers (PDOP/PAN). The prepared silver coated PDOP/PAN (Ag/PDOP/PAN) nanofibrous composite membrane exhibited an outstanding catalytic performance, and showed good reusabil- ity for completely degradating methylene blue (MB) dyes and reducing o-nitroaniline very quickly, respectively.

Preparation of palladium membrane by bio-membrane assisted electroless plating for hydrogen separation

Palladium membrane was prepared on the inner surface of alumina tube by bio-membrane assisted electroless plating combined with osmosis method (BELP). In this preparation technique, an egg-shell film not only served as a semipermeable membrane to form osmotic system for preparing palladium membrane, but also acted as a protection layer to prevent the contamination of the palladium membrane from the osmotic solution. Moreover, the plating solution was circulated through the tube side to promote the mass transfer on the solid–liquid interface between the plating surface and the solution. The detailed depositing process of the palladium membrane was studied by scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDXS). Both long term operation and temperature cycling test carried out for hydrogen and nitrogen permeation confirmed that the palladium membrane was stable.

Surface engineering characteristics of ultrasound assisted hypophosphite electroless plating baths

This article addresses the characteristics of metallic skin layer and the performance of hypophosphite based ultrasonic electroless plating baths during the fabrication of nickel/ceramic microfiltration membranes. The process performance was evaluated in terms of overall conversion and metal plating efficiency, and the metal film was characterised in terms of average film pore size, average effective porosity, film thickness and per cent pore densification. Parametric investigations were carried out for a wide range of initial nickel solution concentrations (0·04–0·16 mol L−1) at two different loading ratios (196 and 393 cm2 L−1) for sonication coupled electroless plating. A simple mass transfer model was developed to provide insights with respect to the pertinent mass transfer limitations. Sonication resulted in faster deposition rate, better efficiency and improved surface morphology. In comparison with conventional and agitated electroless plating baths, ultrasound assisted electroless plating provided the best combination of process as well as performance characteristics.

Ag-Coated PAN Nanofibers Prepared by Poly(dopamine)-Assisted Electroless Plating

Silver-coated PAN nanofibers have been prepared by a facile method that combined the electrospinning technique and electroless plating method. Dopamine was used to functionalize the surface of electrospun PAN nanofibers to form the chemisorption sites in order to assist electroless plating of silver. SEM and ATR-FITR results indicated that poly(dopamine) has been successfully deposited on the surface of PAN nanofibers. XRD and SEM results also showed that face-centred cubic (fcc) crystal Ag nanoparticles with uniform size were well coated on the surface of electrospun PAN fibers.

Ni–P-multiwalled carbon nanotubes composite coatings prepared by mechanical attrition (MA)-assisted electroless plating

A mechanical attrition (MA)-assisted electroless plating technique has been developed to deposit Ni–P-multiwalled carbon nanotubes (CNTs) composite coatings on carbon steel. MA was applied via the glass balls in a stirring bath containing electroless plating solution and CNTs. This article discussed the microstructure, phase composition and mechanical properties as compared to the conventional electroless plating. EDS results showed that the MA-assisted coating possessed 59wt.% CNTs, which was much higher than that of 22wt.% in conventional coating. The composite coatings also exhibited the minimum coefficient of friction value of 0.14. However, the surface hardness decreased and the wear weight loss slightly increased after heat treatment at 400°C for 1h. The mechanisms accounting for the formation of composite coating and the unique mechanical properties were further discussed.

Microstructure and friction performance of copper film fabricated by ion implantation assisted electroless plating on PTFE

The polytetrafluoroethylene (PTFE), which was implanted with Ni ion to different energy and doses, fabricated metallic structures by selective electroless copper plating. The characteristic and microstructure of the copper film were studied using SEM and X-ray diffraction. Friction performance of the interface between copper film and basal body of PTFE was tested with a CETR UMT-2 (CETR Co., Campbell, CA, USA) multifunction micromechanics instrument. The test loads were 10, 20 and 40 N, while the line velocity was 8 mm s−1, and the frequency of data acquisition was 1 Hz. The Ni ion implantation replaces the complicated electroless plating surface pretreatment, and it is an assisted technique of electroless plating of copper on the surface of PTFE and plate Cu directly on its surface. Continuous, prepressing and uniformity plating was obtained with proper technique parameters and the dosage of Ni+. The frictional performance comprehensive property of copper film was remarkably influenced by different plating methods, annealing treatment and testing loads under unlubricated condition. The friction coefficients and wear rates changed with the varied load. Annealing treatment improves the tightness and uniformity of the copper film, while it decreases its cavity. Friction performance of copper film was thus increased. The mechanisms of friction and wear of copper film under different test conditions are also discussed.

Performance characteristics of hydrothermal and sonication assisted electroless plating baths for nickel–ceramic composite membrane fabrication

This paper addresses the performance characteristics of nickel–ceramic composite membranes fabricated with hydrothermal mass transfer coupled electroless plating baths. Deposition of nickel on a ceramic membrane support with an average pore size of 275 nm was considered to study the effect of autogenous pressure under hydrothermal conditions and sonication coupled hydrothermal conditions on the process as well as membrane characteristics. Bath conversion, plating efficiency, average film thickness and percent pore densification (PPD) were studied. Parametric investigations were carried out for wide range of initial nickel sulfate concentration (0.04–0.16 mol/L) in the solution at a higher loading ratio (393 cm 2/L). An interesting observation from this study was that the autogenous pressure together with ultrasound provided the best performance characteristics of electroless plating. The optimal performance characteristics refer to 81.87% conversion, 84.19% plating efficiency, 99.92% PPD for a nickel composite membrane with film thickness of 37 μm prepared using 0.16 mol/L of nickel solution metal concentration. The microfiltration study on oil-in-water emulsions inferred that the membrane fabricated with HTSO coupling and C i = 0.04 mol/L gave a rejection of 90.13% and membrane permeability of 0.11 × 10 − 10 m 3.m − 2 .s − 1 .Pa − 1 .

Effect of Ultrasound on the Performance of Nickel Hydrazine Electroless Plating Baths

This article addresses the relationship between morphology of metallic skin layer and process parameters of hydrazine-based electroless plating baths during the fabrication of nickel-ceramic microfiltration membranes. While process performance was evaluated in terms of overall conversion and metal plating efficiency, the film morphology was characterized in terms of average metal film thickness, pore size, and percent pore densification. Sonication was considered as an additional degree of freedom to the conventional electroless plating process. Process parameters varied include initial nickel solution concentration (0.04–0.16 mol/L), loading ratio (196 and 393 cm2/L), and relevant mass transfer coupling (sonication). It was observed that sonication assisted electroless plating provided the best combination of both process as well as performance characteristics in comparison with the base case and membrane stirred cases. Ultrasound was found to enhance the selective conversion by more than 50% compared to the other cases. About 50–100% excess nickel plating rate was evaluated for the sonication assisted case due to which the membranes with pore size as low as 11 nm were achieved.