Electroless Plating Bath Research Articles

Synthesis and characterization of Ni-based infiltration brazed coating reinforced with Co-P shell-coated WC

In this work the interface and wear resistance of Ni/WC infiltration-brazed cladding was increased by incorporating WC@Co-P reinforcements. This was achieved by depositing a Co-P nano-shell on the WC particles using the electroless plating technique. The morphology of the powders and the thickness of the Co-P shell were examined using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), respectively. The phase compositions were analyzed through energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results revealed that by optimizing the parameters of the electroless plating bath, a uniform Co-P shell with an average thickness of 80 nm was successfully deposited onto the WC particles. Through FESEM and EDS analyses, it was observed that the WC@Co-P/NiCrBSi coating exhibited higher compactness compared to conventional Ni/WC coating, along with a more homogeneous distribution of reinforcements. Additionally, unlike WC/NiCrBSi coating, no abnormal growth of particles occurred during molten phase sintering. Underpinning these findings are results from Pin-On-Disk tests which demonstrated notable improvements in various wear properties for the Co-P modified coating compared to conventional Ni/WC coating. Specifically, there was a 33 % increase in the coefficient of friction (0.3), a 40 % reduction in wear rate (0.006 g/Km), and a 26 % increase in hardness (1500 Vickers). These enhancements highlight the potential benefits offered by incorporating WC@Co-P reinforcements in improving interface quality and wear behavior for Ni/WC infiltration-brazed coating materials.

Investigation of Deposition Conditions and Basic Properties of CNF Composite Ni Plated Film by Electroless Plating Method

Ni-cellulose nanofiber (CNF) composite plated films were fabricated by electroless plating method. The deposition conditions and basic properties of the Ni-CNF composite film were investigated. A C1100 plate was used as the plated material, and a Ni-P electroless plating bath was prepared as the plating solution. 5 g/L of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) oxidized CNF or carboxymethyl cellulose was added to the plating solution. Sodium dodecyl sulfate (SDS) was added as a surfactant. It was confirmed that CNFs were complexed on the surface of the plated film, and the addition of SDS made CNFs disperse into the plated film. The surface of the plated film obtained by adding both TEMPO oxidized CNF and SDS had the highest Vickers hardness among all conditions investigated.

Development of electroless NiSnP plating with excellent bath stability using nickel hydroxide

ABSTRACT In general, NiSn alloys are known as plating films with elegant lustre and excellent corrosion resistance. Electroplating methods have already reached a practical application level because high Sn-containing films can be obtained. On the other hand, electroless plating methods have not yet reached the level of practical application because the Sn content in the deposited film is not only low but also the corrosion resistance is not sufficient. The authors have studied in detail the composition of electroless plating baths to obtain NiSnP films with Sn content above 50 wt%. In particular, the plating bath using nickel hydroxide instead of nickel sulphate as the Ni source increased bath stability and obtained high Sn content. The effects of Ni source in the bath on the deposition films were studied. The bath using nickel hydroxide as the Ni source was almost unaffected by the bath ratio. Furthermore, the amount of dissolved oxygen (DO) in the plating bath also varied depending on the Ni source, affecting the composition of the deposited film and the bath stability. It was confirmed that electroless plating baths using nickel hydroxide have excellent bath stability and can be applied to a relatively wide range of plating operation conditions to obtain high Sn-containing films. In addition, the corrosion resistance was improved by increasing the Sn content in the film. It was also confirmed that the NiSnP with high Sn content does not dissolve in nitric acid.

α-Fe2O3/Fe3O4@GO nanosheets boost the functionality of Ni[sbnd]P thin film deposited by electroless method

The highly active heterogeneous iron oxide@graphene oxide (α-Fe2O3/Fe3O4@GO) composite was produced using a simple assembly method to incorporate into the electroless NiP thin film to enhance its performance. It was thoroughly characterized using X-ray diffraction (XRD), Raman Spectroscopy, Fourier transformed infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), and N2 adsorption-desorption tests. The outcomes showed that the α-Fe2O3/Fe3O4 nanoparticles were uniformly and densely distributed on the GO sheets, with a tiny diameter of about 160 nm.Ni-P/α-Fe2O3/Fe3O4@GO composite coatings were created on low-carbon steel using an acidic electroless plating bath containing various α-Fe2O3/Fe3O4@GO nanosheets. The protective effect of co-deposited nanosheets on the corrosion behavior of the coatings was examined in a 3.5 % NaCl solution. Electrochemical techniques, including electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization investigations, were used to evaluate the layers' corrosion resistance. The outcomes demonstrate that adding α-Fe2O3/Fe3O4@GO significantly increases the coatings' ability to resist corrosion. Maximum corrosion resistance was achieved at a dosage of 50 mgl−1 α-Fe2O3/Fe3O4@GO nanosheets in the plating bath. According to the SEM images the α-Fe2O3/Fe3O4@GO were implanted in the NiP matrix and were evenly disseminated over the coated surface. Moreover, the incorporation of α-Fe2O3/Fe3O4@GO enhances the mechanical properties of NiP thin film.Because of its improved performance, ease of synthesis, and low cost, this coating layer warrants more consideration as a good option for possible application to safeguard carbon steel utilized in the atmosphere.

Direct electroless plating of conductive thermoplastics for selective metallization of 3D printed parts

Electroless plating is a promising approach for metallizing plastic 3D printed parts, but current approaches rely on surface activation with expensive precious metal catalysts such as palladium. In this work, we demonstrate conductive composite filaments loaded with metal or other conductive particulate can be electrolessly plated directly, without prior activation, with exposed particles serving as nucleation sites. Several commercially available filaments based on different particulate loading were plated, with both carbon black and copper particulate shown to nucleate in an electroless copper plating bath. Flash ablation metallization, the use of a flash of high energy white light to ablate the polymer on the surface and expose a higher density of metal particulate, was also shown to accelerate the plating process. Selective plating was then achieved through use of a dual extruder 3D printer to define conductive composite regions for plating on a non-conducting thermoplastic. Trace resistances were reduced by as much as five orders of magnitude after copper plating. A toroidal inductor was printed and shown to drop in resistance from 24 kΩ before to 2.3 Ω after plating, with post-plating inductance and quality factor 315 nH and 10.3 respectively. A 555 timer circuit demonstrator was also plated.

The effect of fluoride on the formation of an electroless Ni–P plating film on MAO-coated AZ31B magnesium alloy

This study adds fluoride to the electroless nickel-phosphorus (Ni–P) plating solution to prevent the deterioration of MAO-coated AZ31B Magnesium alloy after contact with an electroless plating bath. During the electroless Ni–P plating process, fluoride reacts with Ni2+ ions and the MAO coating to form interphases (NaMgF3), which exhibit good bonding and corrosion resistance. NaMgF3 buffers H+ ions formed from the initiation of Ni–P deposition, preventing the interface of materials from damaging the MAO coating with H+ ions. As immersion time increases, nickel is scattered over the coating.The fundamental data for MAO/Ni–P coated AZ31B Mg alloy determines whether there is fluoride in the electroless Ni–P plating solution. The results show that the coating for a fluoride-containing solution is more resistant to corrosion than those in fluoride-free solution. The compositions, structure and morphology of the MAO/Ni–P coatings that formed for different working parameters are determined using energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The corrosion resistance of the MAO/Ni–P coatings is calculated in a 3.5 wt.% NaCl solution using a potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS) and a salt spray test (SST).

A study of dielectrics generated by electro-less electrochemical method for semiconductor devices

The aim of this work is to the basic concepts of the varies chemical and electrochemical procedures used m the fabrication of semiconductor devices seems to be useful to provide a suitable background for the present work, a brief review of the same as also the results obtained by earlier workers has been undertaken at the outset. A careful scrutiny of the results obtained by different workers reveals that although the aforesaid methods have a few limitations, they may be satisfice borily used as an alternative to sputter and evaporation techniques for device fabrication. The author carried out experimental investigations on the formation and properties of ohmic contact to silicon using two electroless plating baths - one operated at room temperature and the other at 95°C. In particular, the variation of contact resistance of ohmic contacts formed by electroless Ni-P process on silicon was studied as a function of sintering temperatures with operating point temperatures and pH of the baths as parameters. ^rom these studies it has been shown that both the baths yielded an adherent and dense deposit of nickel-phosphorous alloy on n-Si, which when sintered at very high temperatures give a less value of contact resistance due to the formation of metal-n -n contact. The phosphorous component of the Ni-P deposit diffuses into n-Si during heat treatment and forms the metal-n+ --n contact which behaves as an ohmic contact. As expected, the value of contact resistance was found to decrease with the increase of phosphorous materials in the deposit. The most favourable temperature range of heat treatment was found to be between 600°-700°C. Heats studying above 700°C slightly less increase the contact resistance probably due to the out diffusion of phosphorous from the Ni-P deposit. The barrier height and ideality factor are two important parameters for m-s contacts. The values of these two parameters of electrochemically fabricated Schottky diodes as obtained from the capacitance and current voltage characteristics were found to be in fairly close agreement with those of vacuumevaporated diodes. It is therefore, concluded that the electrochemical method of metal deposition is a valid and convenient technique for the fabrication and study of metalsemiconductor contacts

Increasing the structural and compositional diversity of ion-track templated 1D nanostructures through multistep etching, plastic deformation, and deposition

Ion-track etching represents a highly versatile way of introducing artificial pores with diameters down into the nm-regime into polymers, which offers considerable synthetic flexibility in template-assisted nanofabrication schemes. While the mechanistic foundations of ion-track technology are well understood, its potential for creating structurally and compositionally complex nano-architectures is far from being fully tapped. In this study, we showcase different strategies to expand the synthetic repertoire of ion-track membrane templating by creating several new 1D nanostructures, namely metal nanotubes of elliptical cross-section, funnel-shaped nanotubes optionally overcoated with titania or nickel nanospike layers, and concentrical as well as stacked metal nanotube-nanowire heterostructures. These nano-architectures are obtained solely by applying different wet-chemical deposition methods (electroless plating, electrodeposition, and chemical bath deposition) to ion-track etched polycarbonate templates, whose pore geometry is modified through plastic deformation, consecutive etching steps under differing conditions, and etching steps intermitted by spatially confined deposition, providing new motifs for nanoscale replication.

Effect of Heat Treatment and Applied Load on Mechanical and Tribological Properties of Ni-B-CeO2 Composite Electroless Coating

Cerium oxide (CeO2) particle reinforced Ni-B composite coating was produced by electroless coating method from a Ni-B coating bath containing CeO2 particles. In the electroless plating bath, nickel sulfate hexahydrate ((NiSO4.6H2O) was used as nickel source, dimethylamine borane ((CH3)2NHBH3) as reducing agent, thiourea (CH4N2S) as stabilizer and sodium acetate (CH3COONa) as complexing agent. The aim of the study is to investigate the structural characterization of CeO2 particle reinforced coating and the effects of wear test conditions on its tribological properties. The surface morphology of the coating was performed by scanning electron microscope (SEM), and phase structure analysis was performed by X-ray diffraction (XRD). Nanohardness measurements were carried out with a nanoindenter device, and wear tests were done with a ball-on-disk test device. Worn surface analyzes were made using a 3D profilometer. Experimental results showed that the hardness of the coating increased with heat treatment; however, its tribological behavior changed depending on different loads

Tyrosine as a novel potential stabilizer in an electroless Ni-P bath exempt of trisodium citrate as complexing agent: Chemical baths optimization and comparative study

• New formulation of Ni-P alloy electroless plating baths using hypophosphite as reducing agent. • Abundance of trisodium citrate as the main component acting as a complexing agent in Ni-P electroless plating baths. • Addition of tyrosine as a complexing-stabilizing agent led to a significant improvement in bath stability accompanied by a deposition rate of 18 µm h −1 . • Optimization of the tyrosine-containing bath led to a gain of 67% NiSO4,6H2O and 85% CH 3 COONH 4 . The effect of tyrosine (C 9 H 11 NO 3 ) as a new stabilizing agent on the composition and conditions of the electroless plating bath of the Ni-P alloy was studied. A comparative study with trisodium citrate, which is commonly used, as a stabilizing complexing agent revealed the effect of tyrosine in this study. Scanning electron microscopy (SEM) and X-Ray Energy Dispersion (EDX) are used to study the properties of the Ni-P coating deposit developed in the presence of tyrosine and trisodium citrate. The result of this optimization showed that the use of tyrosine causes the concentration of NiSO 4 and CH 3 COONH 4 in the bath to decrease to 67% and 85%, respectively. In contrast, the use of trisodium citrate had no effect neither on the composition nor on the effect of the bath conditions of the deposit. In addition, the use of C 9 H 11 NO 3 as a stabilizing agent in the bath promotes the increase of the phosphorus content more than trisodium citrate when optimizing the accelerating agent in the bath and therefore changes the structure of the Ni-P deposits developed.

Electrochemical Characteristics of Nickel Hydroxide Fabricated from a Spent Electroless Plating Bath

Electrochemical Characteristics of Nickel Hydroxide Fabricated from a Spent Electroless Plating Bath

Effect of Graphene Enrichment on Solid Particle Erosion Performance of Electroless Ni-P Composite Coatings

Abstract Solid particle erosion (SPE) and dents (from contact loads) are among numerous surface degradations in the hydrocarbon industry that can in turn compromise the longevity of protective coatings. Both these degradation mechanisms can induce cracks that allow the corrosive solutions to seep through those cracks and corrode the underlying metal, thereby defeating the purpose of surface protection. Nickel-phosphorus (Ni-P) coatings have been known for decades for their corrosion resistance, but their applications in hydrocarbon industries are impeded by their tribological limitations, namely low wear resistance. In the current research work, graphene nanoplatelets were introduced to an Ni-P electroless plating bath in various concentrations (30 mg/L, 60 mg/L, and 100 mg/L) to achieve three different compositions of ternary Ni-P–graphene coatings, namely Ni-P-30 mg G, Ni-P-60 mg G, and Ni-P-100 mg G, respectively. Surface roughness was characterized via topography employing a laser confocal microscope. Coating hardness was characterized using Vickers hardness and the composition analyses were carried out via energy dispersive spectroscopy. SPE was conducted via Tungsten carbide (WC) erodent ball at three different impact angles and two different particle velocities. Finally, Hertzian indentation was performed under two different loads to characterize the denting behavior of coatings. Eroded and dented coatings were further visualized via an optical microscope. The highest concentration of graphene (by 18 vol.%) in Ni-P-30 mg G coating improved the hardness, leading to the smallest size of indents during both SPE and Hertzian indentation. Also, Ni-P-30 mg G exhibited no evidence of cracking under normal impact angle and particle velocities of 35 ms−1 and 52 ms−1.

Electroless Plating Cycle Process for High-Conductivity Flexible Printed Circuits

In this work, a non-formaldehyde electroless plating cycle process was successfully applied to prepare the flexible copper printed circuits on poly (ethylene terephtalate) (PET) films. Copper nanoparticles (Cu NPs) were employed as catalytic seeds, and dimethylaminoborane (DMAB) was used as the reductant. Cu NPs were directly printed on the PET surface modified by 3-mercaptopropyltriethoxysilane (MPTES) to serve as the seeds to trigger the electroless deposition. MPTES modification can dramatically improve the adhesion of the PET and Cu layer. Cu NPs can ideally substitute noble metals Ag, Pt, and Pd to catalyze electroless deposition. DMAB, as an innocuous reductant can replace formaldehyde in an alkalescent plating bath. The amount of Cu NPs with different sizes on the per area of the PET surface was investigated to determine its appropriate dosage. Various times, temperatures, concentrations of reactants in the electroless plating process were researched to obtain optimal deposition. The minimal sheet resistance of the copper pattern was 6 mΩ/sq with a resistivity of 2.01 μΩ·cm, which is 1.18 times that of bulk copper. These results demonstrated that the prepared Cu pattern had excellent conductivity. The kinetics of the electroless plating process was researched to quantify the thickness of the Cu layer and the consumption of reactants. The electroless plating bath can well be cycled after compensating reactants, while the sheet resistance of the Cu pattern fluctuated very little. The cycling electroless plating bath will greatly reduce the discharge of waste and is of vital significance for the large-scale and cheap manufacturing of flexible printed electronics.

Dispersion stability of zinc oxide nanoparticles in an electroless bath with various surfactants

Stable dispersion of nanoparticles in electrolytes is essential for preparing a wide range of advanced electroless nanocomposites. However, nanoparticles agglomerate if the van der Waals attractive forces prevail over the electrostatic repulsive forces. As a result, various surfactants (anionic, cationic, and non-ionic) were used to prevent nanoparticle agglomeration in the electroless plating bath. This study specifically examines the dispersion stability of zinc oxide (ZnO) nanoparticles in an electroless bath with different surfactants, including anionic sodium dodecyl sulfate (SDS), cationic cetyltrimethylammonium bromide (CTAB), and non-ionic polyvinylpyrrolidone (PVP). The zeta potential and hydrodynamic diameter measurements were utilized as an indicator of nanodispersion stability. The results showed a better-dispersed state of ZnO nanoparticles with SDS surfactant with a small average size of the agglomerate. Surfactants SDS and CTAB improved stability by electrostatic repulsion between ZnO nanoparticles whereas PVP by steric inhibition towards other particles. In addition, ultraviolet–visible absorbance spectroscopy (UV–Vis) was used to examine the dispersion stability of ZnO nanoparticles with different surfactants. The nano-ZnO distributed with SDS displayed a maximum percentage of absorbance, suggesting the homogeneous dispersion of ZnO nanoparticles.

Replacement of Copper Cyanide by Copper Sulfate on Electroless Brass Plating Process

Environmentally friendly processes and health protection are industrial requirements nowadays. Surface finishing industry demands the improvement of the composition of bath solutions, and specifically, reduction or elimination of the use of toxic substances to simplify complexity on wastewater treatment. This work presents results on the replacement of copper cyanide by copper sulfate in the composition of an electroless brass plating bath used on zamak alloy coating. The effect of the concentration of copper sulfate on the morphological and brass film color characteristics was studied. Characterization of plated pieces was made by scanning electron microscopy, optical microscopy, L*, a*, b* color parameters and by spectrophotometry and electrochemical techniques. Results indicate that copper cyanide can be successfully substituted, being possible to control the color of brass plating on this new process.

Metal-plastic hybrid 3D printing using catalyst-loaded filament and electroless plating

Abstract The metallization of local areas of 3D-printed plastic structures has attracted a significant amount of attention. However, metal and plastic additive manufacturing technologies are incompatible with each other due to the significant difference in their associated process temperatures. This paper proposes and demonstrates a plastic 3D printing technology that adopts electroless plating, a form of chemical metal deposition. The technology is capable of metalizing selected areas of 3D-printed plastic structures made of acrylonitrile butadiene styrene (ABS). Because electroless plating is triggered by a palladium (Pd) catalyst, this study designed and custom-fabricated an ABS filament that contains palladium chloride (PdCl2) as a catalyst precursor, which can be used in a fused filament fabrication (FFF) 3D printer. The 3D printer has two nozzles. One produces the main component of the ABS 3D structure using a regular filament (i.e., pure ABS without PdCl2), and the other deposits a PdCl2-loaded ABS layer onto a selected area of interest using the custom filament. Then, the 3D-printed structure is directly immersed in a nickel (Ni) electroless plating bath. The Ni coats the selected area with strong adhesion. The proposed plastic 3D printing technology coupled with electroless plating does not require any etching (which often uses chromic acid, a very toxic chemical) or roughening of the ABS structure, which are necessary for conventional electroless plating on plastic structures for strong adhesion. Overall, the proposed 3D printing technology has several advantages, namely area-selective metallization, compatibility with regular FFF 3D printing, no damage to the printed structure, and environmental friendliness.

TiO2 nano-particle effect on the chemical and physical properties of Ni-P-TiO2 nanocomposite electroless coatings

TiO2 nano-particles were used in electroless plating bath to obtain Ni/P/nano-composite coatings. The coatings were heat treated at 200, 400, 600 and 700 oC and their chemical and physical properties were investigated and it was found that 400 oC was the optimum temperature for the heat treatment of the coatings. The micro-hardness test of coatings showed that the composite coatings, which contain TiO2 nano-particles, exhibit better properties of microhardness. X-ray diffraction (XRD) analysis indicated that at 400 oC, Ni3P phase is formed, and when the heating temperature is 600 oC the presence of TiO2 particles is seen. We have used scanning Electron Microscopy (SEM) to measure the surface morphology of the composite and plane deposits. Weight loss measurement, Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization Spectroscopy were utilized to study the corrosion resistance of coatings in 3.5 %wt NaCl solution. Corrosion resistance experiments indicated that presence of TiO2 nano particles in the electroless coatings matrix improved the corrosion resistance of the coatings. Heat-treatment improved the corrosion resistance of the coatings up to 400 oC but heating above 400 oC caused a decrease in corrosion resistance. Wear behavior of the samples indicated that presence of TiO2 particles improve the wear resistance.

Electroless Nanoplating of Pd−Pt Alloy Nanotube Networks: Catalysts with Full Compositional Control for the Methanol Oxidation Reaction

AbstractDue to its simplicity, flexibility and conformity, electroless plating presents itself as an attractive route towards functional metal nanostructures. Despite the importance for creating multimetallic materials with enhanced properties, the complex interactions between the components in electroless plating baths make alloy formations a challenging objective. In this work, we outline an electroless plating strategy fabricating Pd−Pt alloy nanomaterials, which is based on arbitrarily miscible plating baths for the individual metals. To demonstrate the excellent nanoscale conformity and homogeneity of our plating system, we apply it to ion track‐etched polymer templates with large inner surfaces as ambitious substrates, resulting in the formation of 3D free‐standing PdxPt100‐x‐nanotube‐networks (NTNWs). Based on the electro‐oxidation of methanol as a model reaction, we utilize the compositional freedom provided by our syntheses for optimizing the catalytic performance of our metal NTNWs, which heavily depends on the Pd−Pt ratio. Within our system, the highest surface normalized activity was found for the Pd20Pt80 NTNW, reaching more than a two‐fold increase of the peak current density in comparison to pure Pt. Overall, our reaction system provides a versatile toolkit for fabricating intricate Pd−Pt nanostructures of arbitrary elemental composition, and constitutes a starting point for designing new electroless alloy plating baths.

Effect of Graphene Nanoplatelets (GNPs) Addition on Erosion–Corrosion Resistance of Electroless Ni–P Coatings

Erosion–corrosion is one of the major damage mechanisms incurring higher maintenance cost for hydrocarbon industries. Various damages resulting from service conditions have necessitated protective coatings such as Ni–P. Although Ni–P electroless coatings are known for their corrosion resistance and anti-wear behaviors, still there is a dire need for increasing the anti-wear and anti-corrosion behaviors to expand potential application of Ni–P coatings in oil and gas and petrochemical sectors. In this work, graphene enrichment in Ni–P coating matrix was performed achieving various compositions of ternary Ni–P-graphene coatings through the addition of various concentrations of graphene (30 mg/L, 60 mg/L and 100 mg/L) into electroless plating bath. Surface topography and micro-structural examinations of coatings were conducted. Slurry pot erosion–corrosion testing (using AFS 50–70 silica sand and 3.5 wt% NaCl solution) was employed to characterize the erosion–corrosion behavior of the coatings. SEM analysis was performed on the wear scars to identify the dominant wear mechanisms. Addition of graphene improved the pure erosion and erosion–corrosion resistance. Ni–P-100 mg G coating displayed best slurry pot erosion–corrosion resistance. It is believed that higher hardness, impermeability, and hydrophobic nature of graphene are responsible for improved performance of ternary coatings.

Structural, morphological and mechanical properties of electroless Ni-B based alloy coatings

The electroless Ni-B alloy coatings are prepared using an alkaline plating bath with nickel chloride as the source of nickel ions and sodium borohydride as the reducing agent as well as the source of boron ions in presence of zinc acetate in the plating bath. The effect zinc acetate concentration on plating rate, chemical composition, surface morphology, structural characteristics, hardness and wear properties of the electroless Ni-B alloy coatings are evaluated. The boron content in the Ni-B alloy coating decreased from 3.69 wt% to 3.26 wt%, when the zinc acetate concentration increased from 1 g/l to 4 g/l in the electroless plating bath. The scanning electron microscopic observation revealed formation of corn-cob like structure on the coating surface. The X-ray diffraction analysis confirmed the crystalline nature of the Ni-B alloy coatings. The microhardness values of the Ni-B alloy coatings decreased from 650 HV to 507 HV, when zinc acetate concentration in the plating bath increased from 1 g/l to 4 g/l.