Electroless Ni-B Research Articles

ANN-NSGA-assisted investigation of tribo-performance of lead-free nickel boron coating

In recent times electroless Ni-B coatings free of lead are being investigated with an aim to replace the lead stabilized bath. Traditional formulations of Ni-B coatings often rely on the use of heavy metal/lead-based stabilizers. However, the environmental and health concerns associated with these stabilizers have prompted the exploration of stabilizer-free formulations. The tribological behavior and wear mechanisms of heat-treated heavy metal-free Ni-B coatings were investigated systematically by varying load (10–50 N), speed (0.5–1.5 m/s) and distance (400–1000 m) in accordance with Taguchi's L27 orthogonal array. An artificial neural network (ANN) combined with genetic algorithm is proposed to investigate and optimize wear rate and coefficient of friction (COF) of heat-treated Ni-B coatings. Globular morphology was obtained for the coatings with crystalline peaks of Ni, Ni3B and Ni2B for coatings heat treated at 350°C for 1 h. The mean absolute percentage error of ANN model for wear rate and COF was 5.2846% and 2.0572%, respectively. The multiobjective optimization showed 30.325 N load, 0.50007 m/s speed and 759.2959 m distance corresponding to simultaneous minimum wear rate and COF of 0.005297 × 10−6 g N−1 m−1 and 0.25238 respectively. The worn surface of optimized conditions coatings exhibited oxidized flattened nodules and debris that act as load bearing area leading to lower wear rate and COF.

Tribological behavior of electroless Ni-B ternary and quaternary coatings with inclusion of W and Mo

Electroless nickel coatings help to tailor requisite surface properties in materials for use in various applications. The aim of the present study is to examine the tribological behavior of electroless nickel-boron coatings incorporated with Mo and W. The coated layers are developed over pin samples with various bath compositions. The coated specimens are characterised to assess their basic features. The tribological tests are carried out with the help of a pin-on-disc tribo-tester under dry conditions. The coating characteristics are determined to comprehend the importance of tungsten as well as molybdenum concentration in electroless nickel-boron coatings. In the as-deposited state, all the coated specimens displayed a surface morphology resembling cauliflower. Moreover, the roughness of these coated surfaces in their as-deposited state showed an increase corresponding to the concentration of the bath parameter, resulting in a higher coefficient of friction (COF). The addition of Mo into Ni-B matrix promotes the coarse grained and cracked surface morphology leading to highest friction coefficient value of as-deposited Ni-B-Mo coatings. The highest surface roughness of Ni-B-Mo coatings also leads to the highest specific wear rate due to breaking and crushing of roughness peaks. The present study reveals the effect of incorporation of W and Mo in electroless Ni-B coatings to control the friction and wear characteristics of the specimens. This will help in deciding the proper electroless bath compositions for specific tribological applications.

THE EFFECT OF BATH TEMPERATURE ON THE STRUCTURE AND TRIBOLOGICAL BEHAVIOR OF ELECTROLESS NI-B–MO COATINGS OBTAINED FROM STABILIZER-FREE BATH

Conventional electroless Ni–B–Mo (ENB–Mo) deposits are formed using hazardous lead or thallium-containing solutions, which must be removed. In this study, ENB–Mo deposits were developed in a bath free of stabilizers and harmful heavy metals. This study estimates the effect of variation of coating bath temperature on tribological performance of ENB–Mo coating developed over AISI 1040 steel. The chosen bath temperatures were [Formula: see text]C, [Formula: see text]C, and [Formula: see text]C to achieve ENB–Mo coating with varying B and Mo content. The 12–15 [Formula: see text]m thick coating was uniform. In comparison to steel substrate, all of the coatings show enhanced corrosion resistance. In the as-deposited state, coatings were mixed amorphous and nanocrystalline with peak of Fe overlapping with Ni. Moreover, TGA results revealed that inclusion of molybdenum enhanced coatings thermal stability. The worn specimens at [Formula: see text]C reveal development of shielding tribo-oxide coatings and existence of microstructural changes. At high working temperatures ([Formula: see text]C), wear debris also has a major impact on tribological mechanisms of coatings. Correlation between microstructure, tribological behavior, and corrosion resistance have also been conducted for ENB–Mo coatings.

A Systematic Investigation of Lead-Free Electroless Ni-B-W Coating Properties Using Taguchi’s Methodology

Electroless Ni-B (ENB) coatings have industrial importance due to their excellent mechanical properties. The inclusion of W (ENB-W) to the coatings further enhances their mechanical properties and thermal stability. Nevertheless, the ENB or ENB-W coatings are deposited from a heavy metal-stabilized bath, and the very commonly used stabilizer is lead nitrate. The present work is an attempt to obtain an ENB-W coating with enhanced mechanical properties and elimination of the stabilizer from the bath. To achieve this, the coating bath temperature, the heat treatment temperature and the heat treatment duration were varied systematically following a strategy adopted from Taguchi’s experimental design. The mechanical properties targeted include surface microhardness and scratch hardness. Multi-objective optimization was performed using gray relational methodology. The predicted bath temperature was 85 °C, while the predicted heat treatment temperature was 450 °C and there was 3 h of heat treatment time. The optimized lead-free ENB-W coatings had a microhardness of 1096.2 HV100 and scratch hardness of 13.86 GPa. In fact, single-objective optimization for surface microhardness and scratch hardness by Taguchi’s methodology also predicted the same optimal parametric condition for both scratch hardness and surface microhardness. This was comparable to that of a lead-stabilized ENB-W coating and higher than the as-plated stabilizer free ENB-W coatings. The coating failure of the optimized ENB-W alloy was tested using a progressive scratch test, which showed that there was no chevron or transverse cracks within the load range considered. Analysis of corrosion resistance revealed that the corrosion potential of the optimized coatings was −407 mV, and this was comparable to that of a lead-based ENB-W coating.

Deposition and process parameter optimization of electroless Ni-B coating from a stabilizer free bath to achieve enhanced microhardness, scratch-hardness and adhesion using taguchi’s methodology

Electroless nickel boron coatings have wide industrial usage. However, they are generally obtained from a lead-stabilized bath. The present work investigates and optimizes the scratch-hardness and microhardness obtained from stabilizer-free electroless nickel boron bath in a quest to eliminate lead nitrate/heavy metals, which are potentially toxic. The bath temperature, heat treatment temperature, and duration were varied at three levels. Enhanced scratch-hardness (12.581 GPa) was obtained at 85 °C bath temperature and heat treatment at 350 °C for 1 h. At the same time, the highest microhardness (886.17 HV100) was obtained at a parametric combination of 95 °C bath temperature and heat treatment at 450 °C for 1 h. Multi-objective optimization was carried out using grey relational analysis. The parametric combination predicted in multi-objective optimization was 85 °C bath temperature and heat treatment at 350 °C for 1 h where the microhardness was 846.34 HV100. Furthermore, an analysis of variance was also carried out to investigate the importance of the factors in controlling scratch-hardness and microhardness. The highest contribution was observed from heat treatment duration. Further investigation of the optimized coating was done by the progressive scratch test, which recorded that the first critical load of failure improved compared to non-heat treated electroless Ni-B coatings. The coatings were also characterized using field emission scanning electron microscope, energy dispersive x-ray spectroscopy, and x-ray diffraction. The coatings in optimized condition showed no transverse or chevron cracks within 5–24 N.

Effects of propylamine and ethylenediamine intercalation of α-ZrP on the corrosion resistance and tribological properties of electroless Ni-B coatings

In this study, propylamine and ethylenediamine intercalated α-ZrP nanocomposites (denoted by P-α-ZrP and E-α-ZrP, respectively) were synthesized. The effects of propylamine and ethylenediamine intercalated α-ZrP nanocomposites and their reinforcements on the corrosion resistance and mechanical properties of Ni-B coatings were investigated and compared. The morphology and structure of the three composites were characterized using transmission electron microscopy, atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, infrared spectroscopy, thermogravimetric analysis, and particle size analysis. Both propylamine and ethylenediamine intercalation increase the layer spacing of α-ZrP, but do not change the lamellar structure of α-ZrP. The EIS test results show that both Ni-B/P-α-ZrP and Ni-B/E-α-ZrP composite coatings have significantly lower corrosion rates than Ni-B and Ni-B/α-ZrP composite coatings. Compared to Ni-B/α-ZrP, the corrosion rates are reduced by 32 % and 76 % respectively. The Rct values for Ni-B/P-α-ZrP and Ni-B/E-α-ZrP composite coatings are also distinctly higher than Ni-B/α-ZrP, with Ni-B/E-α-ZrP having the highest values. In addition, Ni-B/P-α-ZrP and Ni-B/E-α-ZrP composite coatings are both harder than Ni-B/α-ZrP and have lower average coefficients of friction and wear rates than Ni-B/α-aZrP. Among them, the Ni-B/E-α-ZrP composite coating has the highest microhardness (1163.64 ± 21.20 HV) and the best wear resistance. The wear rate is reduced by 87 % and 65 % compared to Ni-B and Ni-B/α-ZrP composite coatings respectively. In conclusion, both P-α-ZrP and E-α-ZrP are better than α-ZrP in terms of enhancement, with E-α-ZrP being the best.

Investigation of the Supercapacitive Behavior of Electroless Ni-B Coatings

Amorphous electroless Ni-B coatings were deposited on steel substrates with different surface morphologies and B contents (6.5–8.64 wt.%) that could be changed by altering the temperature and the composition of the baths. The supercapacitive behavior of the coatings was evaluated by cyclic voltammetry and galvanostatic charge–discharge measurements, and it was found that Ni-B coatings had higher capacitance than pure electroless Ni or the bulk Ni plate. A close relationship was identified between the microstructure, the B content, and the capacitive behavior of the coatings. The presence of the B alloying element had the most significant effect in determining the capacitance, while the surface area and particle size also contributed to its increase. A surface-specific capacity of 31 mF/cm2 was achieved by the coating containing the highest B content and largest AFM surface area. Furthermore, it was revealed that the particle size of the deposits was determined by the combined effect of the bath temperature and the B content under the applied experimental conditions. The obtained results indicate that Ni-B coatings are promising candidates for supercapacitive applications.

Scratch and corrosion behaviour study of electroless Ni-B reinforced with ultrasonicated nano TiO2

The present investigation is a study into the scratch and corrosion response of as-coated Ni-B-TiO2 as compared to the as-deposited Ni-B coatings. Ultrasonicated nano TiO2 particles were used to reinforce electroless Ni-B coatings. The presence of hard nano TiO2 particles improved the scratch hardness of the Nickel-Boron-TiO2 coatings. During the scratch test for an applied load of 20 N, the Nickel-Boron-TiO2 coating showed a decrease of 42 % in scratch width as compared to the Ni-B coatings. Corrosion behavior also showed remarkable improvement with the addition of nanoparticles. As compared to the Nickel-Boron coatings, the corrosion potential Ecorr improved by 5 % while the corrosion current density Icorr showed a 1.5-fold decrease for Ni-B- TiO2 coatings. The double-layer capacitance Cdl which is a qualitative indicator of the porosities present in the coatings was nearly halved with the addition of TiO2 nanoparticles. The specimen underwent SEM analysis for the morphological study and scratch testing to determine the scratch hardness and corrosion behaviour to identify the electrochemical response to a corrosive environment.

Wearable nonwoven fabric decorated with Fe3O4/rGO/PANI/Ni-P for efficient electromagnetic interference shielding

The design of three-dimensional (3D) architectures with different multi-interface and the identification of suitable nanomaterials have significantly progressed in recent years. However, balancing increasing electrical conductivity and optimising impedance matching is substantially important and requires special architecture. Here, we devised lightweight wearable electromagnetic interference (EMI) shielding materials with promising microwave absorption performances. Layer-by-layer integration of conducting and magnetic nanomaterials onto the porous structure of the nonwoven fabric was performed using dielectric and magnetic loss to enhance the absorption capability of the composite. The EMI shielding effectiveness of the 1-layer, 2-layer, and 3-layer reach up to 27, 42, and 81 dB, respectively, revealing excellent performances in the X-band. The synthesis of hierarchical Ni-P nanospheres on fibres with heterojunctions and multi-interfaces as polarisation centres results in excellent microwave absorption performance. Furthermore, Ni-P electroless plating and Ni-B chemical deposition were conducted to improve permittivity, conductivity, and permeability in addition to increasing the impedance matching of the EM shielding material. It provides an avenue for the architecture of promising wearable functional materials with superior absorption activity, flexibility, durability, and breathability.

Development of Ni-B electroless coating from stabilizer free bath and characterization of high temperature tribological behaviour, scratch and corrosion resistance

The current work investigates the effects of variation of coating bath temperature on friction and wear behaviour of electroless Ni–B (ENB) coatings developed from stabilizer free bath. Coating is applied to specimens made up of AISI 1040 steel. Coatings were deposited at three different coating bath temperatures (85 °C, 90 °C and 95 °C). Field emission scanning electron microscopy, inductively coupled plasma-optical emission spectrometer, and x-ray diffraction were used to characterize the coating for surface morphology, chemical composition, and phase structure respectively. Pin-on-disc tribo-tester was used to estimate the friction and wear behaviour of ENB coatings at room temperature (25 °C), 100 °C, 200 °C and 300 °C. The coefficient of friction was higher at high temperature due to higher roughness of the coatings obtained from stabilizer free bath, adhesion and ploughing. The wear rate at 200 °C or 300 °C was lower compared to 100 °C. Additionally, the ENB coatings were subjected to thermogravimetric analysis which reveals higher thermal stability of coatings obtained at 95 °C. A scratch tester at constant (6 N) and progressive load (5–24 N) was used to estimate the coatings scratch hardness and adhesion. The corrosion behaviour of ENB coatings in 3.5% NaCl was studied using potentiodynamic polarization tests. The Ni-B coated specimens could efficiently provide barrier protection to steel substrate. But the corrosion potential was lower compared to lead stabilized bath.

Tribological Electroless Ternary Ni-B-W Coatings: A Suitable Alternative to Hard Chromium Coatings

Abstract Concerns raised about the environmental ramifications of electrodeposited hard chromium (EHC) plating are perhaps the paramount challenge posed to the finishing industries to find a suitable alternative. Electroless Ni-B coatings have attracted much attention due to their superior mechanical and tribological properties; those are enhanced further in electroless Ni-B-W coatings. Electroless Ni-B-W can be a suitable alternative for the replacement of EHC in a variety of engineering applications. In the present study, the changes in morphological features, deposition rates with respect to time, and deposition mechanisms of electroless Ni-B-W coatings are studied thoroughly. After heat treatment, all deposited coatings are characterized thoroughly for the evaluation of their mechanical and tribological characteristics. This is helpful in the comparison of characteristics with properties of industrial EHC coatings. To analyze the coating-substrate adhesion in the electroless depositions, scratch tests with progressive load and repetitions are carried out. Frictional behavior and failure mechanisms at the scratch tracks of all fabricated coatings are also studied through repetitive scratch tests. Heat treatment of electroless Ni-B-W coatings induced significant improvements in mechanical, tribological properties and adhesion behavior. The present study establishes beyond doubt that owing to a specific set of properties, electroless Ni-B-W coatings show tremendous potential to be recommended as a replacement for chrome coatings.

Effect of heat-treatment temperature and borohydride concentration on corrosion behaviour of ENB coating

Electroless Ni-B (ENB) alloy coatings are extensively used due to their good tribological, physical, electrical and mechanical properties. The behaviour of coatings generally depends on the concentration of bath parameters, heat-treatment temperature, as well as heat-treatment duration. The current study was carried out to deposit coatings over steel specimens with various NaBH4 concentrations and heat-treated at various temperatures to study the significance of NaBH4 concentration as well as heat-treatment temperature on corrosion resistance of the Ni-B coatings. Ni-B coatings were heat-treated for an hour at different temperatures for example, 350°C, 450°C and 550°C. Electrochemical impedance spectroscopy (EIS) and Potentiodynamic polarization (PDP) test methods were employed to analyse the corrosion behaviour of the as-deposited as well as heat-treated coatings. The tests were conducted against a corrosive environment consisting of 3.5% NaCl solution. It was observed that the as-deposited coatings with low boron content exhibit a mixture of amorphous and nanocrystalline structures. The same gradually becomes amorphous with the rise in sodium borohydride concentration. The increase in boron content with sodium borohydride concentration in the coating bath led to the transformation of phase structure. This amorphous phase structure of as-deposited coatings further transforms into a crystalline structure upon heat treatment. This crystallinity increases with heat-treatment temperature. The as-deposited coatings show cauliflower-like surface morphology at all concentrations of NaBH4 but the same becomes a coarse-grained structure with clustered aggregates leading to a rough surface. The as-deposited coatings show better corrosion resistance behaviour compared to heat-treated ones, especially at the higher temperature.

Effect of NaBH4 concentration on hardness and microstructural properties of electroless deposited St-37 steel

In this study, electroless Ni-B depositions were achieved on the St-37 steel substrates at different NaBH4 concentrations and 950 oC and 1 hour. Electroless Ni-B deposited samples had a cauliflower-like surface texture that makes the electroless Ni-B deposited surface lubricating naturally and as the NaBH4 concentration increased, the grain size decreases in the microstructure. XRD spectra of the sample showed partial amorph region together with the crystalline region. Microhardness testing of the deposited samples were performed with a microhardness tester under a load of 25 g and an indentation time of 10 s. The highest hardness value was obtained in the sample prepared with 1.4 g/l NaBH4 concentration.

Corrosion Performance of Annealed Electroless Ni-B Coatings on Mild Steel

The coating of Ni-B on mild steel substrate using electroless plating and corrosion performance after annealing at temperatures of varied levels for an hour was researched. The result showed the electroless Ni-B coating was amorphous while coated and also after annealing at 400°C for about one-hour, crystalline nickel and borides of nickel were formed. The corrosion test was carried out using the as-coated and annealed samples in the electro chemical analyser. The sodium chloride solution of 3.5 wt. % was used as a medium of corrosion for the test. The micro strain and crystallite size were calculated from the XRD as a result of which, the annealing temperature raised the rate of corrosion on the coating.

A Hybrid Approximation to Wear Analysis in Electroless Ni-B Coatings: Conformity of Experimental and Finite Element Methods

A Hybrid Approximation to Wear Analysis in Electroless Ni-B Coatings: Conformity of Experimental and Finite Element Methods

The Effects of Potassium Iodate as an Environment-Friendly Stabilizer on Preparation and Properties of Electroless Ni-B Plating

The Effects of Potassium Iodate as an Environment-Friendly Stabilizer on Preparation and Properties of Electroless Ni-B Plating

Evaluation of high temperature tribological behavior of electroless deposited NiB–Al2O3 coating

This paper investigates the tribological behavior of the electroless NiB and NiB–Al2O3 coatings on mild steel (St-37) substrates. The temperature-dependent wear setup was used to evaluate the high temperature tribological behavior of the coatings. The effects of Al2O3 concentration, wear testing configuration, and testing temperature on the predominant wear mechanism of the coatings were discussed in detail. The tribological tests were performed at 25 °C, 200 °C, 400 °C and 600 °C using a ball-on-disk setup to investigate how the temperature affects the tribological behaviors of the coatings under the constant applied load of 3 N. The experimental results showed that, NiB–Al2O3 coating exhibited lower wear rate at all operated test temperatures and the addition of Al2O3 nanoparticles improved the wear behaviors of the coatings. The tribological behaviors of the coatings were confirmed using Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and Raman Spectroscopy.

A comparative study on morphological, mechanical and tribological properties of electroless NiP, NiB and NiBP coatings

The aim of this paper is to fabricate the NiBP polyalloys coatings by electroless coating technique on the aluminum substrate. A comparative investigation of morphological and hardness properties between NiP, NiB and NiBP coatings is employed. Also, the effect of heat treatment process on the nanoindentation behaviors of the electroless nickel-based alloys is studied. The highest hardness of 8.76 GPa and Young's modulus of 180.36 GPa were obtained electroless NiBP coatings in the case of as-plated conditions. After heat treatment process at 400°C in an inert atmosphere, electroless NiB coatings showed the highest hardness value of 10.02 GPa and Young's modulus of 207.48 GPa when compared with NiP and NiBP coatings. Although electroless NiB coatings exhibited the highest Young's modulus and harness value, electroless NiBP coatings showed the best protection against wear in all loads of 1, 2 and 3N and all sliding velocities of 100, 200 and 400 mm/s due to showing H/E ratio of NiBP coatings comparing with NiB and NiP coatings.

Regression-BPNN modelling of surfactant concentration effects in electroless Ni[sbnd]B coating and optimization using genetic algorithm

Critical micelle concentration (CMC) is an important factor to avoid the formation of micelles from monomeric surfactant molecules. Trisodium citrate stabilized electroless NiB (ENi-B) coating on aluminium alloy (Al7075-T6) is attempted with the addition of amphoteric surfactant, 3-(N, N-Dimethylmyristylammonio) propanesulfonate (3-DMAPS), to enhance the surface finish (Ra) of the coatings. The main aim of the study is to investigate the influence of surfactant concentration on average surface roughness in ENi-B bath and determine the CMC of 3-DMAPS at minimum Ra. Mathematical models relating the concentration of amphoteric surfactant (0–0.162 g/L) as an independent variable and Ra as a dependent variable are developed using univariate regression analysis (Linear, quadratic, power, and exponential models) and back propagation neural network (BPNN) algorithm. The coefficient of determination (R2) is used to evaluate the goodness of fit between the models, and the BPNN model is found to be the best fit (R2 > 0.98). The minimum Ra of 0.171 ± 0.001 μm was achieved at the CMC of 0.049 g/L (0.135 mM) from the genetic algorithm (GA) using the validated models developed by quadratic regression analysis and BPNN as fitness functions. SEM, XRD and AFM techniques were carried out for the characterization of ENi-B coatings with and without surfactant at CMC.

Optimization of Ni-B coating bath and effect of DMAB concentration on hardness and wear

In this study, reducing agent amount, stabilizer amount, coating bath temperature and stirring speed parameters were examined for optimization of electroless Ni-B coatings, and the effect of reducing agent amount on hardness and wear of the coating was investigated. The pH of the electroless Ni-B coatings made for 1 h was set to 6, nickel chloride (NiCl2.6H2O) as the nickel source, sodium acetate (C2H3NaO2) as the complexing agent, thiourea as the stabilizer (CH4N2S) and DMAB ((CH3)2NBH2) as the reducing agent was used in the coatings. The bath parameters were varied as; the amount of reducing agent (2 g/L, 3 g/L and 4 g/L), coating bath temperature (65°C, 70°C and 75°C), stabilizer amount (0.5 mg/L, 1 mg/L, and 2 mg/L) and stirring speed (250, 300 and 350 rpm). After determining the optimum conditions, the effects of the amount of reducing agent on the coating were examined. Scanning Electron Microscopy (SEM), X-ray diffractometer (XRD), Vickers nano-hardness test and tribometer were used for characterization of coatings. In the optimization studies, it was observed that the coating morphology was in the form of cauliflower and columnar structures were formed in the cross-section images. According to optimization results on the morphologies, the samples which compact and free-crack have been investigated phase structure, hardness and tribology properties. In XRD analysis, coatings produced with different amounts of reducing (DMAB) are amorphous as-deposited, after annealed at 400°C for 2 h, nickel borides (Ni2B and Ni3B) phases are formed and increased the preferential orientation (111) of the nickel crystal plane. The effect of DMAB concentration on coating was examined in as-deposited condition and post annealing. The formation of nickel borides after annealing increases the hardness. The effect of DMAB concentration on the coating after annealed was examined and it was observed that the wear resistance of the dense and homogeneously dispersed sample in the coating matrix was more perfect than other samples. Consequently, hardness (850 HV), coefficient of friction (0.37) and wear rate (2.92 × 10−7 mm3/Nm) of B2 sample which free-crack and compact was obtained. These results indicate a high strengthen B2 sample produced with 3 g/L DMAB concentration and 70°C bath temperature could utilize in a harsh medium.