Electroless Nickel Phosphorous Research Articles

The effect of phosphorous content on the microstructure and localised corrosion of electroless nickel-coated copper

A detailed microstructural and electrochemical analysis of electroless nickel phosphorous (NiP) coatings with P contents of 13.2 ± 1.2 wt%, 12.9 ± 0.7 wt%, and 8.3 ± 0.8 wt% on a copper substrate was performed to study the corrosion behaviour of electroless NiP/Cu systems. The P content of the electroless NiP coatings plays an essential role in the microstructure of the coatings in terms of crystallinity. The crystallinity variations, representing the extent of crystalline and amorphous phases within the material, with P content, affect the local electrochemical characteristics and, hence, the corrosion protection behaviour of electroless NiP coatings. The coatings with the highest P content showed the best corrosion performance in a 3.5 wt-% NaCl solution. In contrast, the surface of the electroless NiP coatings with low P content is more susceptible to corrosion due to the presence of locations with heterogeneous electronic properties that initiate localised corrosion. Microgalvanic interactions with a high cathode-to-anode surface ratio govern the localised corrosion kinetics of the low P-content samples. A high concentration of nodule boundaries and/or other existing structural defects on the surface serve as anodic sites, whereas the remainder of the surface serves as cathodic sites.

Asymmetric surface texturing for directional friction control under dry sliding condition

This study investigated the effects of asymmetric surface texturing on directional friction under dry condition. Asymmetric micro-grooves were radially textured on electroless nickel phosphorous (Ni–P) plated disk using a single-point diamond cutting process. Using a ball-on-disk tribometer, sliding tests in clockwise (CW) and counter-clockwise (CCW) directions against polyether-ether-ketones (PEEK) material were carried out at different texture densities. Results show that asymmetric surface texturing has a strong effect on directional friction. At a texture density of 70 %, the friction coefficient in the CW direction increased by 28.1 % compared to the CCW direction. The greatest increase in friction coefficient, 61.3 %, was observed during CW rotation at the lowest texture density compared to the reference untextured surface.

Wear and mechanical properties of electroless NiP and NiP-Silicon Carbide (SiC) composite coatings on En8 steel

Electroless coating technique is widely used in various industrial applications. This coating is the decision for some design applications with different actual attributes of electroless Nickel coatings, for example, hardness, wear resistance and coating thickness. The major advantages of Electroless Ni-P coatings are uniform coating thickness, improved wear and corrosion resistance, hardness, ability to deposit on surface activated non-conductors etc. In this article, a pure Nickel phosphorous (NiP) and Nickel phosphorous-Silicon Carbide (SiC) composite coatings are deposited on En8 steel using electroless coating to enhance the mechanical and wear properties of En8 steel. The wear test was carried out using Pin on Disc Tribometer against the counter part of stainless steel at atmospheric condition with various process parameters such as load, sliding velocity and sliding distance. The surface hardness and elemental composition of the coating were analyzed by Vickers hardness test and Optical Emission Spectroscopy respectively.

Reactive Bilayers by Self-activated Electroless Nickel-Phosphorous Deposition on Pure Aluminum

Nickel-aluminum bilayers and multilayers are commonly used in reactive systems because of their high heat of mixing. Traditionally, the layers are sputter deposited, an expensive and time-consuming process. In this article, a chemical reduction technique, electroless nickel-phosphorous (EN) deposition, is used for formation of the Ni-Al bilayer using a pure Al substrate. Traditionally, EN deposition on Al requires surface activation due to the native oxide layer. Here, we tune the bath pH to dissolve this oxide layer, such that deposition can be obtained without surface activation. Deposition kinetics is measured by tracking the mass change with time and temperature, and we extracted the activation energies at two different pH values. At pH 7, the energy is 98.7 kJ/mol and reduces to 55 kJ/mol at a pH of 8. The process can also be extended to aluminum powders and flakes in order to form reactive core–shell structures.

Electroless deposited black nickel-phosphorous solar absorber coatings on carbon steel: Effect of plating bath pH

One of the challenges of solar energy collection is energy conversion efficiency, particularly the absorbent surface capability to convert solar energy to thermal energy. In this work, nickel-phosphorous (Ni-P) coating was deposited onto a carbon steel substrates using the electroless plating process containing nickel sulfate as the nickel source and sodium hypophosphite as the reducing agent. This study focuses on the study of plating bath pH effect on the light absorption properties of the black surface after blackening process and at the same time maintain the characteristic of protective coating to protect the substrate from corrosion. The electroless nickel plating was conducted at various plating bath pH (4.5, 5.0, and 6.0) for 3 h at a constant bath temperature and composition. Electroless black Ni-P surfaces were obtained through an etching process of Ni-P coating with 9 mol/L nitric acid solution. The surface morphology of Ni-P coating and black Ni-P coating were observed using scanning electron microscopy (SEM). The chemical composition of Ni-P coating deposited at various pH was measured using energy dispersive X-ray (EDX) equipped on the SEM. The SEM results show that black Ni-P coating for pH 4.5 sample has the highest porosity which is 47.1% of the surface area with highest phosphorus content shown by EDX analysis. The cross-sectional analysis showed that the depth of the etching effect occurred only up to the 33% of the coating thickness. The remaining 67% of coating thickness still uniformly attached on the substrate without the presence of any defects or flacking after the etching process. The visible near-infrared spectrophotometer, (VIS-Nir) showed that the black Ni-P coating of pH 4.5 sample had the highest absorption capability which is 92% of light absorption due to its high surface roughness.

Monolayered versus multilayered electroless NiP coatings: Impact of the plating approach on the microstructure, mechanical and corrosion properties of the coatings

Electroless nickel-phosphorous (NiP) coatings were produced on low carbon steel substrates for a total plating time of 3 h. Different preparation modalities were pursued. Multilayered coatings were produced by stacking three layers of the same composition by successive electroless plating with rinsing steps in between. On the other hand, coatings termed ‘monolayered’ for the sake of comparison were deposited by one step electroless process, with and without undergoing bath replenishment of the electrolyte during plating. All the samples were subjected to thermal annealing at 400 °C for 1 h under argon atmosphere.The results show that the multilayer approach prevents crack propagation in the as-deposited coatings because the interfaces between layers block the advance of defects. Bath replenishment during monolayered coatings production creates pseudo-interfaces similar to those of the multilayered case but they are ineffective in terms of corrosion protection. Un-replenishment of the electrolyte promotes a change in the coating's microstructure from lamellar to columnar which severely worsens their performance. Upon annealing, the presence of interfaces, along with the recrystallization of the metallic matrix, promotes an upgrading of the corrosion performance of the multi-layered coatings. The corrosion products spread laterally at the interface where they stockpile. At a certain point, the accumulation of these by-products provokes the exfoliation of the outermost layer exposing the layer underneath to the corrosive media, thereby delaying the advancement of the corrosion attack. The results of this study highlight the importance of the plating approach selection, as well as the need for proper electrolyte maintenance during the production of high-performance electroless coatings.

Fabrication and investigation of the scratch and indentation behaviour of new generation Ni-P-nano-NiTi composite coating for oil and gas pipelines

Oil and gas pipelines operate under severe mechanical and chemical conditions, which could lead to catastrophic failure. Electroless nickel-phosphorous (Ni-P) coatings are an excellent candidate for protection against wear and corrosion for oil and gas pipelines. Ni-P coatings exhibit superior corrosion resistance over many commercially available coatings, as well as high hardness. However, electroless Ni-P coatings suffer from low toughness, which has limited its use in applications where high scratch and dent resistance is required. To enhance the toughness of the Ni-P coatings, nano-sized particles of superelastic NiTi alloy were incorporated within the coating. In the present work novel Ni-P-nano-NiTi composite coating has been successfully plated on API X100 pipe steel. Scratch tests under constant and increasing loads were performed to determine the effect of NiTi nano-particles on wear damages. Indentation tests were carried out to assess the dent resistance and crack modes of the coating. The addition of superelastic nano-particles into the Ni-P matrix led to toughening through transformation toughening, crack bridging, deflection, and microcracking. The composite coatings exhibited lower hardness in comparison to monolithic Ni-P coatings, but still provided considerable improvement upon the steel substrate. Optical and scanning electron examinations showed evidence of delamination, radial, and Hertzian cracking, as well as a reduction in crack length with the addition of superelastic NiTi.

Effect of electroless bath composition on the mechanical, chemical, and electrochemical properties of new NiP–C3N4 nanocomposite coatings

C3N4 nanosheets, which have high hardness and excellent thermal and chemical stability, were used in the electroless nickel-phosphorous (NiP) bath to deposit the NiP–C3N4 nanocomposite coatings (NCCs) on API X100 carbon steel (CS). The effect of plating time, pH, surfactant type and C3N4 concentration on the mechanical, chemical, and electrochemical properties of the electroless NiP–C3N4 NCC were thoroughly stated. The morphology and structure of the NiP–C3N4 NCC were investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The results indicated that the alkaline electroless bath produced a NiP–C3N4 NCC with a microhardness 250 HV200 higher than that produced from the acidic one. A small addition of polyvinyl pyrrolidone (PVP) as a surfactant was sufficient for increasing the homogeneity of the nanocomposite coating and, consequently, its microhardness. The corrosion performance of the NiP–C3N4 NCC prepared at the optimum conditions was studied in a 3.5 wt% NaCl solution through electrochemical impedance spectroscopy (EIS) and Tafel analysis techniques. An electroless bath of 0.5 g L−1 C3N4 offered a nanocomposite coating with the highest microhardness and superior corrosion resistance. It has an efficiency of approximately 96% that decreased gradually, losing about only 2% after one week and 20% after one month of immersion time in the aforementioned chloride solution.

Performance Evaluation of Nano Additives and Surfactants on the properties of Electroless Nickel Phosphorous Coating on Aluminium – Magnesium Alloy

Corrosion occurs as a result of the interaction of a metal with the environment. The extent of corrosion depends on the type of the metal and the surrounding environment. This paper focuses on the investigation of the corrosion problem in Aluminum–Magnesium alloys and experimentally develops an Electroless Nickel - Phosphorouscoating with different nano additives and surfactants. This paper investigates the different types of Electroless Nickel - Phosphorouscoatings done to reduce corrosion in Al-Mg alloys. Two types of nano particles such as nano Al2O3 and nanoZnO with two types of surfactants such as SDS and CTAB were used in this investigation. Different corrosion evaluation tests such as atmospheric exposure test, and wet corrosion test were carried out on the coated samples. Coated samples were characterized with help of Scanning Electron Microscope and Energy Dispersive X-ray Spectrometry. Mechanical evaluation tests such as surface roughness and hardness were measured on the coated samples. Comparison was done between the different EN-P coatings to optimize the concentration ofnano additives and surfactants.

Impact of nano additives on electroless nickel phosphorous (EN-P) coating

Impact of nano additives on electroless nickel phosphorous (EN-P) coating

Effect of pH on mechanical, physical and tribological properties of electroless Ni-P-Al2O3 composite deposits for marine applications

Successful co-deposition of fine particulate matter within an Electroless Nickel-Phosphorous (ENi-P) matrix is dependent on various factors like bath composition, particle compatibility with metallic matrix, bath reactivity (pH), particle size and their distribution. ENi-P deposits incorporating Al2O3/Alumina in a disperse phase have varied effects on properties and attributes like surface roughness (Ra), microhardness, wear resistance, corrosion resistance and surface morphology of the deposits obtained. This paper experimentally investigates the effect of alumina (1.55 g/L) on Ra, microhardness, surface morphology, deposition rate, wettability, wear resistance and corrosion resistance of ENi-P-Al2O3 composite deposits on mild steel substrates at bath pH 5, 7 and 9. Study reveals that optimum deposit parameters and deposition rates are achieved with bath pH. However, not much study has been undertaken concerning composite deposits obtained from higher bath pH or basic bath. This is attributable to the fact that at higher bath pH or alkaline baths, the bath gets unstable and eventually degrades or decomposes, thereby resulting in sub optimal or poor deposition. Hence, experimental investigations carried out by preparing suitable baths, operating under optimum conditions, and enabling successful composite deposition in acidic and alkaline baths have revealed that there is a significant improvement in the above mentioned properties of the as-deposited composite deposits, as the pH is increased from pH 5 to pH 9. This aspect can therefore be advantageously utilized for preparing various marine components like fasteners, nuts, bolts, washers, pipes, cables, components having relative motion etc.

Tribological Behaviour of Electroless Ni–P Coatings in Brine Solution and Optimization of Coating Parameters Using Taguchi Based Grey Relation Analysis

The present paper deals with the synthesis of electroless nickel–phosphorous (Ni–P) coatings on mild steel substrate and optimization of the coating process parameters for minimum friction and wear in brine solution using Taguchi based grey relation analysis. The study is carried out using different combinations of four coating process parameters, namely, concentration of nickel source (A), concentration reducing agent (B), bath temperature (C) and annealing temperature (D) with three levels each (1, 2 and 3). The wear and friction tests are conducted with a pin-on-disk Wear & Friction Monitor. Taguchi based grey relational analysis is employed for the optimization of this multiple response problem using an L27 orthogonal array. The optimal combination of parameters is found as A3B3C1D2 which yields an improvement in grey grade of 62 % compared to the mean grey grade. ANOVA is performed to find out the significance of the coating parameters and their interactions. Bath temperature and annealing temperature are most influential in controlling friction and wear behavior. The surface morphology and composition of coatings are studied with the help of scanning electron microscopy (SEM), energy dispersed X-ray (EDX) analysis and X-ray diffraction (XRD) analysis. It is found that Ni–P coating is amorphous (weight percentages: 91.56 % Ni and 8.44 % P) in as-deposited condition but gradually turns crystalline with heat treatment. The worn surface morphology reveals abrasive wear mechanism.

Taguchi -Grey Based Optimization of Friction and Wear of Electroless Ni-P Coatings in Acidic Environment

The present study describes the synthesis of electroless Ni-P (nickel-phosphorous) coatings on mild steel substrate and optimization of the coating process parameters for minimum friction and wear in acidic (1M H2SO4) solution using Taguchi based grey relation analysis. The study is carried out using different combinations of four coating process parameters, namely, concentration of nickel source, concentration of reducing agent, deposition temperature and annealing temperature with three levels each. The tribological tests are conducted with a pin-on-disk tribometer. Analysis of variance reveals that annealing temperature has the maximum contribution in controlling the friction and wear characteristics of Ni-P coating. The coating is characterized using scanning electron microscopy, energy dispersive X-ray and XRD analysis, respectively. It is found that Ni-P coating is amorphous in as-deposited condition but gradually turns crystalline with heat treatment. Moreover the wear mechanism is found to be abrasive in nature.

Effect of reducing agent and nano Al2O3 particles on the properties of electroless Ni–P coating

Abstract This work is an experimental study on the formation, characteristics and properties of electroless nickel phosphorous (Ni–P) coatings and electroless nickel alumina (Ni–P–Al 2 O 3 ) coating with varying reducing agent concentration. The results obtained indicate that the deposition rate and surface roughness of both Ni–P coating and Ni–P–Al 2 O 3 coatings are highly influenced by reducing agent (sodium hypophosphite). With increase in sodium hypophosphite Ni forms amorphous phase and as a result the micro hardness of the coating gets reduced. Heat treatment was carried out at 400 °C for 1 h after the coating, resulted in the formation of an intermetallic nickel phosphide (Ni 3 P) phase which improved the hardness of the Ni–P coating from 400 ± 25 to 700 ± 25 HV. A composite coating is formed due to the incorporation of nano alumina in the Ni–P coating leading to an increase in the hardness. The chemical composition of nickel gets reduced from 85.3 to 77.8 wt.% due to the presence of alumina which resists the deposition of Ni. The uniform distribution of alumina particles are observed using a scanning electron micrograph and confirmed by X-ray diffraction techniques. The specific wear rate of Ni–P–Al 2 O 3 coated and post coating heat treated specimens was observed to be less when compared with that obtained in the case of conventional Ni–P coating.

Separation and Recovery of Nickel from Waste Electroless Nickel-Phosphorous Plating Solution

Separation and Recovery of Nickel from Waste Electroless Nickel-Phosphorous Plating Solution

Influence of deposition parameters and kinetics of electroless Ni-P plating on polyester fiber

The electroless nickel-phosphorous (Ni-P) plating on polyester fiber using sodium hypophosphite as a reducing agent in alkaline medium was studied. The effects of plating parameters including concentrations, pH and bath temperature of the plating bath on deposition rate of the electroless Ni-P plating were investigated. The results reveal that the deposition rates increase with the increase in the concentration of nickel sulfate, sodium hypophosphite, pH and bath temperature, respectively. However, it is determined that the deposition rates decrease with the rise of sodium citrate. The kinetics of the deposition reaction was investigated and an empirical rate equation for electroless Ni-P plating on polyester fiber was developed.

Effect of Gold Immersion Time on the Electrochemical Migration Property of Electroless Nickel/Immersion Gold Surface Finishing

In this study, the electrochemical performance of an electroless nickel/immersion gold (ENIG) surface finish was evaluated as a function of the Au immersion time by the water immersion migration test. As the Au plating time increased, the electroless nickel phosphorous (EN-P) changed from amorphous to crystalline and then increased in crystallinity. X-ray diffraction (XRD) was used to evaluate the crystallinity of the plating layer. The electrical resistance of the electrodes was tracked as the sample was immersed in water with a 5 V bias. The microstructures of the electrodes after the electrochemical migration test were observed by using secondary electron microscopy (SEM) and energy dispersive spectroscopy (EDS). As the Au immersion time increased, the EN-P's crystallinity and Au thickness increased. This enhanced the electrochemical migration protection of the surface finish layer.

Dynamic behavior of electroless nickel plating reaction on magnesium alloys

In order to obtain better control over the quality of electroless nickel–phosphorous (EN) coatings on magnesium AZ91D alloy, the effects of metal salt concentrations, reducing agent, pH, and temperature on deposition rate were studied. The reaction orders and activation energy of the deposition were determined. The results show that the apparent activation energy (E a) in the EN plating reaction is approximately 38.03 kJ/mol. The deposition rate increased with increasing temperature, concentration of H2PO2 −, and pH, and decreased with increasing concentration of complexing agents. For nickel ions, the deposition rate increased gradually with increasing concentration (x) when x < 4.69 g/L. However, it decreased when the concentration exceeded 4.69 g/L. Finally, various types of the deposition reaction were also discussed. The results indicate that nickel was first deposited by replacement deposition in the initial 0.5 min, then by both replacement deposition and autocatalytic deposition in plating, and finally by autocatalytic deposition after 5 min of plating.

Effects of (NH 4) 2SO 4 on the characteristics of the deposits and properties of an electroless Ni–P plating solution

The effects of ammonium sulfate (AS) in bath on the deposition rate, hypophosphite efficiency, bath stability, and characteristics of electroless nickel–phosphorous (EN) deposits were studied. The deposition rate of EN deposits was estimated by the gravimetric method. The results showed that the deposition rate of EN can be improved by the addition of AS when its concentration is lower than 12 g dm −3. Bath stability test was used to determine the stabilization effect of AS. The stability of the EN bath can be significantly decreased by a low concentration of AS, whereas a minimal influence on bath stability was observed with an increased concentration of AS. The variation in the efficiency of hypophosphite was also examined by traditional methods of chemical analysis. Characterization of the deposits was carried out by potentiodynamic polarization experiments, scanning electron microscopy, and energy dispersive X-ray, which can analyze the Ni and P content. The results indicated that a low accumulation of AS (lower than 12 g dm −3) in the plating process did not adversely affect the characteristics of the deposits. An optimum concentration of AS can decrease grain size, refine microstructure, and improve corrosion resistance. However, a very concentrated AS plating bath may result in an increase in stress of the coating, hence creating a cracked cross-section morphology.

Corrosion assessment of electroless nickel–phosphorous/nanosilicon carbide composite coatings

Electroless nickel–phosphorous (Ni–P)/nano-SiC (silicon carbide) composite coatings were deposited onto API-5L-X65 steel substrates in the absence of any surfactants at different concentrations of SiC nanoparticles in the plating bath. The hardness and corrosion resistance of the composite coatings with different content of SiC nanoparticles were measured. Moreover, the structure of the composite coatings were investigated by means of X-ray diffraction, whereas their morphologies and elemental composition were analysed using scanning electron microscope equipt with energy dispersive spectrometer. Results showed that co-deposited SiC nanoparticles contributed to increase the hardness, but the corrosion resistance of the composite coatings depends on dispersion of nanoparticles throughout the coatings and decreases because of agglomeration of nanoparticles and porosity of the coatings.