Electroless Nickel Deposition Research Articles

Innovative Pre‐Treatment for Fabrication of Conductive PMIA Fibers via Electroless Nickel Plating

To achieve the admirable electrically conductivity without sacrificing the outstanding integrated performance of meta‐aramid fibers is still a challenge. A novel method is developed for fabricating of electrically conductive poly (m‐phenylene isophthalamide) (PMIA) fibers in this paper. Firstly, the metal silver nanoparticles are deposited on the surface of PMIA fibers by simply dipping the fibers into a mixed aqueous suspension of dimethylsulfoxide (DMSO) and nano silver sol. Then, the silver nanoparticles, depositing on the surface of the PMIA fibers, are functioned as the catalyst for the subsequent procedure of electroless nickel deposition together with the anchor for the coating layer. Followed by electroless nickel plating, homogeneous and dense nickel‐coated PMIA fibers are obtained. And the properties and structures of nickel‐coated PMIA fibers are investigated systematically, the electrical resistance of the nickel‐coated PMIA fibers is measured using the multimeter. Without any post‐treatment, the electrical resistance of the modified PMIA fibers can be as low as 5.5 Ω cm−1. Meanwhile, outstanding mechanical performances of pure PMIA fibers are well maintained. This study also demonstrates the necessity of adding a small amount of DMAB as an auxiliary reducing agent. This approach may be equally applicable to fabricate conductive coatings on other polymer materials.

The influence of iodate ion additions to the bath on the deposition of electroless nickel on mild steel

ABSTRACTAn alkaline hypophosphite bath (0.1 M nickel sulphate, 0.2 M sodium hypophosphite, 0.2 M sodium acetate and 0.1 M malic acid, adjusted to pH 5) was used to produce Ni–P coatings on uncoated and electroless nickel pre-plated mild steel. The deposition was monitored by open-circuit potential-time monitoring vs. a saturated calomel reference electrode and potentiostatic current–time monitoring together with anodic and cathodic polarisation. Classical mixed potential theory was applied to the polarisation data to calculate the effect of controlled iodate ion additions (0–1000 ppm) as an accelerator to the electrolyte on the plating rate. The mixed potential and deposition current density increased gradually with potassium iodate concentration. The use of electrochemical data allowed the optimum iodate additive concentration to be established using simple instrumentation.

Comparative effects of corrosion on electroless -nickel plated A6061 alloys in DOT3 brake fluid

Aluminium alloys used in automobile brake master cylinder pistons wear by corrosion due to contamination and chemical reaction of the contacting brake fluid. The study investigates the corrosion of electroless-nickel (EN) deposition enhanced cast aluminium alloy master cylinder piston surfaces immersed in hydraulic brake oil. Cast specimens were produced from the as-received wrought A6061 alloy scrap by sand casting. EN plated as-received and cast aluminium alloys specimens were immersed fully in brake oil for 1680 hours and corrosion rates were determined every 24 hours. Test samples were characterised using the hardness tester, atomic absorption spectrometer, metallurgical photo-microscope, x-ray diffractometer; and SEM with EDX attachment. Both surfaces corroded in the order of electroless-nickel plated cast aluminium alloy (ENCA) < electroless-nickel plated as-received aluminium alloy (ENAA) at 0.0235 and 0.0251 rates (mg/mm2/y) results which showed improvement in the corrosion resistance with significant influence of electroless-nickel coating in reducing corrosion rates of aluminium alloy in brake oil.

Completely Aqueous Route for Metallization of Structural Polymeric Materials in Micro-Electro-Mechanical Systems

Recent developments in the fabrication of micro-electro-mechanical systems (MEMS) are moving away from the deposition/mask/etch paradigm and instead exploiting useful properties of polymers. Many polymeric insulating materials, such as Parylene, PMMA, HSQ, SU-8 and KMPR, have attracted attention in microfabrication lately, because of their low cost and significantly easy processing procedures [1,2]. Metallization of these polymers is required for their integration in MEMS technology. While conventional microfabrication methods for preparing metallic thin films on insulating substrates are limited to vapor deposition techniques, it has recently demonstrated that electroless deposition can be considered as an alternative and efficient approach [3,4]. Presently used process of electroless plating onto plastics requires a pretreatment based on chromic acid etching for oxidizing the surface. This pretreatment increases the surface energy and wettability for the subsequent step of surface activation with noble metal catalysts. Thus, the development of simple, cost-effective and environment friendly strategies, such as avoiding chromic acid etching and/or minimizing the gravimetric use of noble metal, to metallize the surface of insulating substrates is of huge interest. Here, we report a simple one step covalent amination of the surface of commercial structural polymers employing diazonium-based aqueous chemistry. These amine-terminated functionalities allow minimizing the quantity of palladium cations used as catalyst for the subsequent electroless nickel deposition, as well as offer excellent adhesion between the polymer substrate and the nickel film. X-ray photoelectron spectroscopy is carried out to elucidate the mechanism of surface functionalization with amine groups. We then focus our attention on the comprehensive characterization of the metallic thin film through scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy techniques. Keywords: Metallization of plastics, diazonium chemistry, covalent grafting, environment plating process, MEMS fabrication Reference W. Dai et al., Sensors and Actuators A 135 (2007) 300–307.Y. Liu et al., Progress in Polymer Science 52 (2016) 79–106.Y. Shacham-Diamand et al. Microelectron. Eng. 132 (2015) 35–45.G. Zeb et al., Applied Surface Science 407 (2017) 518–525.

Electroless deposition of nickel on biocompatible poly(dimethylsiloxane) after a laser processing as a pretreatment

Electroless deposition of nickel on biocompatible poly(dimethylsiloxane) after a laser processing as a pretreatment

Deposition and characterization of electroless Ni on fluoride free pretreated AZ91 magnesium alloy

Poor corrosion resistance of magnesium alloys restricts their widespread applications in corrosive environments. The electroless nickel deposition is well established approach to combat the corrosion in various environments but limited due to the usage of various hazardous chemical species such as HF, fluorides and hexavalent chromium. The electroless nickel deposition on magnesium alloys is difficult due to the formation of poor oxide/hydroxide layer which may overcome by facilitating by the suitable surface pretreatment. An environment friendly pretreatment and a novel duplex-electroless nickel (ENi) plating methods on AZ91 magnesium alloy is developed and reported in the present paper. Two types of environment friendly baths, alkaline and acidic were formulated to pretreat the AZ91 magnesium alloy prior to electroless nickel plating. The duplex electroless Ni-P layer was successfully obtained to increase the corrosion resistance of AZ91 alloy; the first layer in alkaline pH (10.5) followed by another Ni-P layer either in alkaline (pH∼10.5) or acidic pH (5.0) bath. Morphology of the coating was characterized by scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDS). Corrosion resistance was characterized by using potentiodynamic and electrochemical impedance spectroscopy (EIS) in 0.5% NaCl solution. Results showed coating with the submicron size nodules produced at alkaline pH while amorphous at an acidic (pH∼5.0). A large increase in the corrosion resistance of AZ91 alloy was obtained with the duplex ENi layer using prior treatment in the phosphoric acid containing solution.

Synthesis and characterization of supportless Ni-Pd-CNT nanocatalyst for hydrogen production via steam reforming of methane

Supportless Ni-Pd-0.1CNT foamy nanocatalyst with specific surface area of 611.3 m2/g was produced by electroless deposition of nickel, palladium and multiwall carbon nanotube (MWCNT) on interim polyurethane substrate. Application of temperature programmed reduction (TPR) and temperature programmed oxidation (TPO) data into Kissinger (Redhead) kinetic model showed lessening of their activation energies due to Pd and CNT addition. Presence of foamy Ni/SiC caused 8% higher steam reforming of methane; while Ni-Pd-0.1CNT presence resulted in 22% higher methane conversion. The catalytic behavior of the samples was described by morphological and compositional studies which were carried out by transmission electron microscope (TEM), field emission scanning electron microscope (FESEM) equipped with energy dispersive spectroscopy (EDS) and atomic absorption spectrometer (AAS) pondered with Brunauer–Emmett–Teller (BET), TPR, TPO and X-ray diffraction (XRD).

The corrosion behavior and mechanical properties of CrN/Ni[sbnd]P multilayer coated mild steel as bipolar plates for proton exchange membrane fuel cells

This research mainly studies on the interfacial conductivity and corrosion resistance of mild steel (MS)/electroless plating nickel (EN)/CrN composite coating. The MS/EN/CrN composite coating is deposited on a mild steel substrate using a combination of electroless nickel plating process and closed field unbalanced magnetron sputter ion plating system. The simulative working environment of proton exchange membrane fuel cell (PEMFC) is implemented to test the electrical and corrosion properties of uncoated mild steel and coated samples. Results show that the performance of the MS/EN/CrN coated samples was greatly improved. The SEM results indicate that the surface of MS/EN/CrN is dense and smooth. CrN (111) and Ni (111) are observed in the MS/EN/CrN coating by XRD. The potentiodynamic polarization and EIS tests show that the incorporation of electroless nickel deposits into the CrN coating can provide better corrosion resistance. Potentiostatic polarization tests reveal that MS/EN/CrN coating has the lowest current density both in anodic and cathodic environment. The Interfacial contact resistance (ICR) results show that the ICR of MS/EN/CrN coated sample reduces to 3.3 mΩ cm2 at a compaction force of 140 N/cm2. Moreover, after potentiostatic polarization, the ICR values of the MS/EN/CrN coating are still less than DOE's 2020 target. In addition, compared with other samples, the hardness and adhesion property of the MS/EN/CrN multilayer coating were greatly improved, which is beneficial for resisting the shock and wear during the assembly process of fuel cell stacks.

MECHANICAL PROPERTIES AND CUTTING PERFORMANCE OF ELECTROLESS TERNARY NI-W-P COATED CUTTING TOOLS

This paper presents a new approach of electroless nickel deposition (END) on cutting tools as to enhance tool performance. END involves several reactions in aqueous solution and is performed without using electrical power. The cutting performance of electroless ternary Ni-W-P alloy-coated cutting tools that were prepared in plating baths with different pH levels and with the addition of heat treatment was investigated. The cutting tool life was evaluated during machining on AISI D2 steel followed by measurement of surface roughness. Experimental results showed that END cutting tools produced from a plating bath with a pH of 8.5 with heat treatment resulted in the longest tool life, which was 7 minutes 32 seconds, and the lowest surface roughness, which was 0.412 μm. High deposition rate and high thickness of coating obtained under such pH condition were found to be the main factors in enhancing tool life. Furthermore, the addition of heat treatment increases the hardness and improves the coating surface.

Chromate and HF free pretreatment for MAO/electroless nickel coating on AZ31B magnesium alloy

Micro arc oxidation (MAO) coating was developed as an interlayer for the electroless nickel (EN) top coat to improve the corrosion resistance of Mg alloy. Prior to the electroless nickel deposition, oxide layer was activated by using NaBH4 solution as a replacement for conventional chromate and HF activation processes. EN coatings were prepared using the alkaline carbonate bath. As-prepared coatings were characterized for the surface morphology and composition using Field Emission Scanning Electron Microscopy (FESEM) attached with energy dispersive analysis of X-ray (EDX). Potentiodynamic polarization studies were carried out in non-deaerated 3.5% NaCl solution to find out the corrosion resistance of the coatings. The MAO coating showed porous morphology with micro cracks whereas, MAO/Ni-P coating exhibited dense nodular structure. The cross-Ni-P and MAO/Ni-P/Ni-W-P duplex al images showed good adhesion between MAO and Ni-P layers. This clearly indicates that the present activation process results in dense with uniform pores of MAO coating along with excellent bonding at the interface for Ni-P coat. The MAO/EN coating combination showed two orders improvements in corrosion resistance as compared with the substrate.

Formation and characterization of multilayers borohydride and hypophosphite reduced electroless nickel deposits

Electroless nickel coatings are popular surface treatments for industrial application because they can provide either excellent corrosion protection (in the case of nickel-phosphorus − Ni-P − coatings) or excellent wear resistance and superficial hardness (in the case of nickel-boron − Ni-B − coatings). The properties provided by both types of coatings are thus complementary and recent work has focused on combining electroless Ni-P and Ni-B in the form of duplex coatings. This work goes further on this research by studying multilayer electroless Ni-P/Ni-B coatings. The Ni–P/Ni–B multilayer coatings were prepared using a commercial bath for the Ni-P coatings and a lab-developed alkaline bath based on sodium borohydride for the Ni-B deposits. Single layers of Ni-P and Ni-B as well as multilayers constituted of 10 layers, alternating between Ni-P and Ni-B electroless bath, were prepared. Scanning electron microscopy (SEM) observations of the cross-sections of the nickel duplex coatings reveal that coatings are uniform with proper compatibility between layers. When compared with the single layers of NiB and NiP the multilayer coatings have better wear and abrasion properties. Scratch test was used to qualify the adherence between the layers. Hardness and adhesion properties are closer to NiP.

Monitoring of zincate pre-treatment of aluminium prior to electroless nickel plating

Zincating is used as a pre-treatment for aluminium prior to electroless nickel deposition during preparation of magnetic computer memory discs. Four immersion zincating solutions were evaluated at 22°C using single step or double zincating followed by electroless nickel deposition from a high phosphorus hypophosphite bath at 90°C. The coating process was monitored by potential vs. time curves obtained under open-circuit conditions during zincating then electroless nickel plating. The surface morphology of the aluminium, at various stages, was imaged by scanning electron microscopy and atomic force microscopy. Zero resistance ammetry was used to record galvanic currents between the aluminium and an inert platinum counter electrode during zincating. This, together with potential-time measurements, provided simple and valuable methods for following the zincating process and subsequent electroless Ni plating. Double zincating enabled a shorter induction time for electroless Ni deposition and resulted in a more complete coverage of the surface by Zn.

Enhancement of Corrosion Resistance of NiCrFeBSi Coatings Obtained by Flame Thermal Spray Process Adding an Electroless Nickel Coating Ni-P

Flame Thermal Spray (FTS) coatings frequently show some porosity and reduced adherence to substrate, which affect its properties, especially its corrosion resistance. In this work, the corrosion resistance of AISI 1018 carbon steel coated by different methods is compared: electroless nickel (EN) coating, NiCrFeBSi obtained by FTS, duplex coatings of an EN deposit on a layer of NiCrFeBSi obtained by FTS and a layer of NiCrFeBSi on an EN deposit. The coatings were characterized using optical microscopy and scanning electron microscopy techniques, EDS microprobe microanalysis, roughness as well as electrochemical polarization tests to obtain the corrosion rate. The results show the enhancement in the corrosion resistance in saline medium of the duplex coatings, especially of the EN coating on FTS layer.

Investigation of the Kinetics and Mass Transport Aspects of Hydrogen Evolution during Electroless Deposition of Nickel–Phosphorus

Electroless deposition of nickel-phosphorus (Ni–P) alloy, facilitated by the use of sodium hypophosphite as reducing agent, is important to many industrial applications. During electroless Ni–P deposition, hydrogen gas evolves as a by-product. In this paper, we first analyze the source of hydrogen evolution. Specifically, we demonstrate that hydrogen gas evolves primarily due to chemical hydroxylation of hypophosphite anions catalyzed by the Ni surface and not due to electrochemical water splitting. Then, using careful volumetric measurements of the rate of hydrogen evolution on a rotating disc electrode, the effects of pH, hypophosphite concentration and hydrodynamics on the hypophosphite hydroxylation reaction are investigated. A mathematical rate expression is formulated, which incorporates the relevant kinetic and mass transport parameters affecting the hypophosphite hydroxylation reaction. Comparison of the model with experimental hydrogen evolution rate measurements allows precise determination of the rate constant and reaction orders. The approach presented herein has broad applicability to the study of gas evolution kinetics in chemical systems where access to the reaction rate is not available through amperommetry.

Surface modification of PEN and PET substrates by plasma treatment and layer-by-layer assembly of polyelectrolyte multilayer thin films and their application in electroless deposition

Surface modification of PEN and PET substrates by plasma-treatment and LbL assembly of polyelectrolyte multilayers and subsequent electroless nickel deposition.

ニッケルおよび無電解ニッケルの超精密切削加工におけるダイヤモンド工具の損耗機構

Diamond cutting tools show severe wear in turning of nickel, while electroless nickel deposits remarkably reduces the wear. To understand the wear mechanism in turning of nickel and electroless nickel, thermodynamics analyses of chemical reaction, erosion tests of diamond contacting with work materials and first principle analyses simulating wear process were carried out. The results show that the essential wear mechanism is the dissociation of carbon atoms on diamond surface due to the interaction with nickel atoms on work surface. Phosphorous addition reduces the dissociation because the interaction is suppressed. The lower cutting temperature in turning of electroless nickel than that of nickel also suppresses the interaction between the diamond and work surface. The easy dissociation of carbon atoms is also occurs with small activation energy due to the reaction with oxygen atoms adsorbed on work surface. However, the process causes a tool wear with very small rate in practical cutting, because the oxygen atoms are difficult to enter into the interface between tool and work material. The results suggest that the machinability of difficult-to-cut materials in diamond turning can be improved by some additional elements.

Rapid Prototyping of a Low-cost Graphene-based Impedimetric Biosensor

This paper presents a preliminary investigation towards rapid prototyping of a low-cost biosensor based on reduced graphene oxide (rGO). The devices are fabricated via a laser scribing process and their functionality is demonstrated by their functionalization and subsequent immobilization of 7% bovine serum albumin (BSA). Non-faradaic electrochemical impedance spectroscopy (EIS) indicated a 33-42% decrease in impedance upon immobilization. An electroless nickel deposition process is demonstrated to enable electrical contacts to the device, with optimized plating conditions (pH, temperature) leading to a rGO-nickel contact resistance of 19 Ω/mm2.

A Study on Electroless Deposition of Nickel on Nano Alumina Powder Under Different Sensitization Conditions

A Study on Electroless Deposition of Nickel on Nano Alumina Powder Under Different Sensitization Conditions

Electroless Deposition of Nickel on Photografted Polymeric Microscale Patterns.

This report demonstrates the electroless deposition of Ni onto micropatterns of poly (acrylic acid) (PAA) photografted to phthalimide-terminated self-assembled monolayers (SAMs). PAA is spin-coated onto phthalimide SAMs and covered with a photomask. UV irradiation selectively binds PAA to exposed regions of the surface, allowing PAA on unexposed regions to be rinsed off. A Pd catalyst is then selectively adsorbed to regions of the surface where PAA is bound. The adsorbed catalyst selectively initiates Ni plating upon immersion of the substrate into a Ni(SO4 ) bath.

Electroless Nickel Deposition: An Alternative for Graphene Contacting

We report the first investigation into the potential of electroless nickel deposition to form ohmic contacts on single layer graphene. To minimize the contact resistance on graphene, a statistical model was used to improve metal purity, surface roughness, and coverage of the deposited film by controlling the nickel bath parameters (pH and temperature). The metalized graphene layers were patterned using photolithography and contacts deposited at temperatures as low as 60 °C. The contact resistance was 215 ± 23 Ω over a contact area of 200 μm × 200 μm, which improved upon rapid annealing to 107 ± 9 Ω. This method shows promise toward low-cost and large-scale graphene integration into functional devices such as flexible sensors and printed electronics.