Ni Coatings Research Articles

Evaluation of the electrochemical active surface area for carbon felt and nanostructured Ni coatings as electrocatalysts for hydrogen evolution reaction

Evaluation of the electrochemical active surface area for carbon felt and nanostructured Ni coatings as electrocatalysts for hydrogen evolution reaction

Introduction of Heavy Micro‐Titanium‐Carbide Particles into Zn–Ni Coatings on Steel During In Situ Brush Electroplating

The heavy micro‐titanium‐carbide (TiC) particles are first introduced into brush‐electroplated Zn–Ni coating (TiC‐0 coating) by using some surfactants here. The effect of TiC concentration of brush‐electroplating solution on the properties of Zn–Ni–TiC coatings is investigated. It is found that the coating hardness and corrosion resistance are enhanced significantly due to the co‐deposition of TiC and an optimal coating with a thickness of 71 μm and adhesive strength of 37.2 MPa is obtained when TiC concentration was 40 (g L−1) (TiC‐40 coating). The pencil hardness of TiC‐0 and TiC‐40 is 2 H and 5 H, respectively. The corrosion resistance time to hot NH4NO3 solution (or inferred neutral salt spray) of TiC‐0 and TiC‐40 are 40 and 240 min (or 321 and 1995 h), respectively. Many pores appear on the coating due to the incomplete overlap of many batch layers. The TiC content is the factor dominating the coating hardness and corrosion resistance by changing the structure, contact angle, and pore diameter of coating, thereby changing the linear polar resistance Rp from potentiodynamic polarization curves, charge‐transfer resistance Rct or |Z|0.01 Hz, or polarization resistance from electrochemical impedance spectroscopy. The content of Zn–Ni alloy is the factor dominating the adhesive strength of Zn–Ni–TiC coating.

Exploring the Effect of Microstructure and Surface Recombination on Hydrogen Effusion in Zn–Ni‐Coated Martensitic Steels by Advanced Computational Modeling

Ultrahigh‐strength steel (UHSS) structures are plated with Zn–Ni coatings because of their excellent corrosion resistance properties, but the plating process is accompanied by the production of hydrogen. The presence of hydrogen in steel results in hydrogen embrittlement. Hence, during the production of UHSS parts, dedicated outgassing steps are employed to remove the diffusible hydrogen from the steel. In a production environment, the real effect of the outgassing process and the outgassing efficiency is unknown for parts coated with Zn–Ni. Hence, a finite element model is developed to capture the evolution of the hydrogen concentration profile in coated UHSS parts during outgassing to study the influence of coating morphology and microstructural features of steel. In order to develop the geometry of the model, scanning electron microscope images are analyzed to understand the microstructure and morphology of the coating. Numerical samples are generated by combining different coating morphologies with steel substrates of varying microstructural features to attain a series of samples with varying features. The results of the outgassing simulations clearly demonstrate the major role of the coating morphology on the hydrogen flux.

The Effect of Ni Interlayer Formation Plating Bath on the Suppression of Oxidation of Ag-Coated Cu Flakes

To suppress Ag dewetting from around 200 oC in Ag-coated Cu (Cu@Ag) flakes, Ag and Ni-coated Cu (Cu@Ni@Ag) flakes were fabricated by successive Ni and Ag electroless plating. The Ni bath type was an important consideration to induce differences in the Ag dewetting and resultant Cu oxidation. An acid Ni bath contained succinic acid as a complexing agent and sodium hypophosphite as a reductant, and an alkaline Ni bath contained sodium citrate as a complexing agent and sodium hydroxide as a pH adjuster as well as sodium hypophosphite. A hydrazine-based Ni bath contained sodium citrate, sodium hydroxide, and hydrazine hydrate as a reductant. The acid Ni bath provided amorphous coatings with a P content of approximately 10 wt%. The Cu@Ni@Ag flakes started the Ag dewetting and Cu oxidation at 350 oC, together with the formation of the Ni3P phase. Meanwhile, the alkaline Ni bath created Ni-5 wt% P amorphous Ni coatings, which transformed into a crystalline phase after heating at 350 oC. The Ag shell was dewetted at 450 oC, which caused oxidation of the flakes. Finally, the hydrazine-based Ni bath formed crystalline coatings without P, which induced rapid mixing with the core Cu. The Ag shells on the mixed Cu-Ni alloy showed repressed dewetting behavior, and thus the dewetting and oxidation temperature was the highest, such as 500 oC. Enhancing the high oxidation resistance at approximately 300 oC will enable the use of Cu@Ni@Ag flakes as a low-cost filler material in conductive pastes, especially for long-time or high-temperature curing.

Characterization and Corrosion Resistance Behavior Study of Pure Ni Coatings and Ni–V2O5 Nanocomposite Coatings Developed by Direct Current and Pulse Current Methods of Electrodeposition

Characterization and Corrosion Resistance Behavior Study of Pure Ni Coatings and Ni–V2O5 Nanocomposite Coatings Developed by Direct Current and Pulse Current Methods of Electrodeposition

Machine Learning-Enabled Quantitative Analysis of Optically Obscure Scratches on Nickel-Plated Additively Manufactured (AM) Samples.

Additively manufactured metal components often have rough and uneven surfaces, necessitating post-processing and surface polishing. Hardness is a critical characteristic that affects overall component properties, including wear. This study employed K-means unsupervised machine learning to explore the relationship between the relative surface hardness and scratch width of electroless nickel plating on additively manufactured composite components. The Taguchi design of experiment (TDOE) L9 orthogonal array facilitated experimentation with various factors and levels. Initially, a digital light microscope was used for 3D surface mapping and scratch width quantification. However, the microscope struggled with the reflections from the shiny Ni-plating and scatter from small scratches. To overcome this, a scanning electron microscope (SEM) generated grayscale images and 3D height maps of the scratched Ni-plating, thus enabling the precise characterization of scratch widths. Optical identification of the scratch regions and quantification were accomplished using Python code with a K-means machine-learning clustering algorithm. The TDOE yielded distinct Ni-plating hardness levels for the nine samples, while an increased scratch force showed a non-linear impact on scratch widths. The enhanced surface quality resulting from Ni coatings will have significant implications in various industrial applications, and it will play a pivotal role in future metal and alloy surface engineering.

Electrodeposition and Properties of Composite Ni Coatings Modified with Multilayer Graphene Oxide.

Within the framework of this study, Ni-based composite electrochemical coatings (CECs) modified with multilayer graphene oxide (GO) processed using microwave radiation have been deposited. The process of these coatings' electrodeposition in the potentiodynamic mode has been studied. The structure of Ni-GO and Ni-GO (MW) CECs has been studied using X-ray phase analysis (XPA) and scanning electron microscopy (SEM).It has been shown that the addition of GO into a nickel deposit contributes to the formation of uniform fine-grained coatings. As a result, the microhardness of the Ni-GO (MW) CECs increases by 1.40 times compared to Ni without GO. The corrosion-electrochemical behavior of nickel CECs in 0.5 M H2SO4 solution was researched. It was established that the corrosion rate of the nickel-GO (MW) CEC in 3.5% NaCl decreases by about 1.70 times in contrast to unmodified nickel coatings. This effect is due to the absence of agglomeration of the graphene oxide in the volume of the nickel matrix and the impermeability of GO particles to the corrosive environment.

The Effect of Laser Cladding Lap Ratio of TC4 Alloy on Microstructure and Properties of Ni60 Coating

For improving wear resistance and hardness, Ni60 coatings were applied to TC4 alloy using laser cladding techniques. The effects of different lap ratios on the microstructure, microhardness, and wear resistance of the Ni60 coating were analyzed using an ultra-deep field microscope, XRD, microhardness tester and wear testing machine, and a suitable lap ratio was sought to obtain a coating with a better performance. The results showed that the Ni60 coatings with a 30% lap ratio had the best morphology and no obvious defects. From the bottom to the top, there are coarse columnar crystals, fine columnar crystals, equiaxed crystals, and acicular crystals, mainly composed of γ-Ni and some Cr7C3 and Cr23C6 phases. Therefore, the suitable lap ratio is 30%, and the microhardness of the coating at this parameter is 900 HV, which is about 2.5 times of the substrate (360 HV). The wear amount of the coating is 5.05 mg, which is about 11% of the substrate (44.23 mg). The average friction coefficient of the coating is about 0.41, which is 63% of the substrate (0.65). TC4 alloy’s wear resistance and microhardness can be significantly improved by applying suitable coating material and laser cladding parameters.

Effect of Micro-Crack Depth on Fatigue Property in Zn–Ni Coated Press Hardened Steel

Effect of Micro-Crack Depth on Fatigue Property in Zn–Ni Coated Press Hardened Steel

Response surface analysis of Zn–Ni coating parameters for corrosion resistance applications: a Plackett–Burman and Box–Behnken design of experiments approach

AbstractThe development of cost-effective coatings with exceptional corrosion resistance is an ongoing challenge in the field of materials science. Among the promising coatings, zinc–nickel (Zn–Ni) coatings have shown great potential, especially when produced using economical electroplating technology. However, achieving optimal performance while minimizing coating thickness remains a complex task. In this study, the behavior of the responses was investigated according to the coating standards and levels, focusing on eight variables including temperature, time, cathodic current density, nickel concentration, substrate hardness, roughness, cathode–anode distance, and magnetic stirring speed. Four responses were investigated: coating thickness, roughness, microhardness, and corrosion rate with potentiodynamic polarization, using two design of experiments (DOE) methods: Plackett–Burman design (12 runs) and response surface methodology with Box–Behnken design (15 runs). The results show the degree of influence of each variable on the responses and their contribution to changing the responses. Additionally, response surfaces have been determined and it is shown that large response values can be achieved with small thicknesses. The morphological study using SEM, EDX, and XRD techniques revealed that the deposition conditions play an important role in the surface morphology. Some samples showed microcracks, while others had small grain size and were free of cracks and pores. Overall, this study provides new insights into the improvement of Zn–Ni coatings with exceptional corrosion resistance and cost-effectiveness.

Influence of vacuum heat treatment on wear behavior of HVAF sprayed WC-Cr3C2–Ni coatings

WC-Cr3C2–Ni coating was deposited on SK5 steel substrate by high velocity air fuel (HVAF) spraying. The effect of vacuum heat treatment temperature on the phase composition, microstructure, microhardness and wear resistance of the coating was investigated. Inspections by scanning electron microscope (SEM) and X-ray diffraction (XRD) indicated that new phases FeW3C and Fe7W6 produced by heat treatment above 550 °C due to metallurgical reaction. When the heat treatment temperature exceeded 700 °C, typical lamellar structure disappeared, and overall uniformity of the coating was improved. The microhardness of the coatings was investigated by Vickers hardness tester and disclosed that the highest value of 1486 HV was detected in coating heat treated at 700 °C, with an increase of 15% compared to as-sprayed condition. The results from ball-on-disk wear test showed that coefficient of friction and wear rate were decreased to varying degrees after heat treatment. The coating heat treated at 700 °C had optimal wear resistance, which wear rate was 1.79 × 10−10 cm3/Nm, approximately 30% lower than as-sprayed coating. Wear equation W=6×10−7×μ/H is obtained to describe the relation between wear rate, coefficient of friction and hardness of the WC-Cr3C2–Ni coating heat treated at 550–1000 °C.

Preparation of a superhydrophobic Ni/SH-SiO2 coating by one-step electrodeposition and an analysis of its anti-corrosion performance

The two-step method limits the large-scale production of superhydrophobic coatings, while low hardness limits the practical application of superhydrophobic coatings. In this study, silane-modified SiO2 nanomaterials (SH-SiO2) were prepared first and then superhydrophobic coatings were prepared by one-step electrodeposition by adding modified materials. In addition, the nonwetting properties, microhardness, mechanical stability and corrosion resistance of pure Ni coatings, Ni/SiO2 coatings, and Ni/SH-SiO2 coatings were compared. The contact angle test shows that the water contact angle (WCA) of the Ni/SH-SiO2 coating can reach 153.858°. The microhardness test shows that the addition of SH-SiO2 can effectively improve the microhardness of the coating and the microhardness of the Ni/SH-SiO2 coating is increased by 76.14% relative to the Ni coating. When the abrasion length reaches 1000 mm, the change of the water contact angle of the Ni/SH-SiO2 coating is kept within 5%, which helps to further promote the practical application of superhydrophobic coatings. Electrochemical impedance spectroscopy tests were used to comprehensively evaluate the corrosion resistance of the coating. The results showed that in a 3.5 wt% NaCl solution, the impedance of the Ni/SH-SiO2 coating is an order of magnitude increase over the other two coatings. Overall, the Ni/SH-SiO2 coatings have excellent corrosion resistance, good hardness and hydrophobicity, and their simple preparation method has positive implications for the large-scale production of superhydrophobic coatings.

Nickel partitioning in ZnNi coatings (Ni less than 4 wt.%) and its effect on the coating corrosion behaviour

ABSTRACT ZnNi alloy coatings with low Ni content (1–4 wt.% Ni) were electrodeposited over mild steel. Ni addition changed the coating morphology from faceted to hillock, decreased the crystallite size, and shifted the basal plane texture to higher energy (011) texture. Zn-1.5 wt.% Ni coating exhibited significantly improved corrosion resistance, even better than the pristine Zn coating. The corrosion resistance properties, however, degraded considerably as the Ni content increased (2.7 and 3.7 wt% Ni). The high corrosion resistance of the Zn-1.5 wt.% Ni coatings was due to the presence of nearly basal texture, low coating strain and evolution of stable γ-phase in the Zn matrix. The corrosion rate for higher Ni addition increased due to high energy surface texture and higher coating strain.

Mechanical optimisation of Ni coatings produced by low-pressure cold spray

ABSTRACT Nickel-based coatings are widely used as thermal barriers in several sectors thanks to their remarkable corrosion and wear resistance and outstanding stability at high temperatures. Recently, Ni coatings, produced with thermal spraying and vacuum techniques, have been investigated for solar power energy applications. In the present manuscript, low-pressure cold spray (LPCS) was used to deposit pure Nickel onto a steel substrate. The influence of gas temperature, nozzle stand-off distance, and advancing speed on morphological and mechanical properties were studied. The optimal deposition conditions were derived by ANOVA analysis. The hardness and the adhesion strength were approximately 160 HV and 26 MPa, respectively. The highest thickness obtained under the optimised deposition with a single pass was around 900 µm.

Numerical analysis of residual stresses induced by cold spray fabricating cBN-reinforced Ni matrix composites

Metal particles used as cold spraying feedstock undergo severe plastic deformation during application. During this process, residual stresses are generated. The presence of porous metal particles and ceramic particles further complicates the deformation process. Numerical models have been proposed to describe the formation process for residual stresses induced by cold spray fabricating cBN-reinforced Ni matrix composites on a 42CrMo substrate. The feedstocks to be sprayed are mixtures of porous Ni particles and Ni-coated cBN particles. The analysis of residual stresses for the cBN-reinforced Ni matrix composites was accomplished by depositing cBN particles on the cold-spayed porous Ni particles and multi-layered Ni coatings. Firstly, local residual stresses are generated near the large number of closed pores inside the cold-sprayed porous Ni particles. Simultaneously, the residual stresses at the bottom of the multi-layered Ni coatings are changed from a compressive stress state to a tensile one as the number of cold-sprayed Ni layer increases. Finally, the deposited cBN particles aggravate the transformation of residual stresses during the cold spraying fabrication of multi-layered cBN-reinforced Ni matrix composites. The concentrated compressive stresses are generated when the cBN particles are deposited on the Ni particles. Understanding these phenomena may provide a guideline for tailoring the residual stresses for cold-sprayed cBN-reinforced Ni matrix composites and thereby improve service performance.

Investigation on the effect of nickel and nickel-chromium alloy pulse current plating on copper substrate

ABSTRACT In the present study, nanocrystalline nickel (Ni) and nickel-chromium (Ni-Cr) alloy coatings were developed on copper (Cu) substrate using pulse current. The pulse current parameters include a cycle time of 240 milliseconds at a duty cycle of 0.5 and 4.17 Hz frequency. The surface morphology, texture, hardness, scratch resistance and porosity were investigated for different coatings developed by pulse plating. Energy Dispersive Spectroscopy (EDS) analysis revealed good quality Ni and Ni-Cr alloy coatings developed on the copper substrate. The peak current of the pulse has been observed to have an impact on the coating weight and thickness. The micrographs of the coatings explored under Field Emission Scanning Electron Microscopy (FESEM), depict uniform coatings consisting of fine primary and coarse secondary granules of Ni and Cr. The hard primary and secondary Ni granules deposited on the surface of Cu increase its hardness, corrosion and wear resistance. Further, it was observed that the Ni-Cr alloy plated samples are harder and less porous in nature compared to Ni plated samples.

Effect of Versenium Hydrogensulfate on Properties of Nickel Coatings.

The salt of formula [H2EDTA2+][HSO4-]2 (dihydrogen ethylenediaminetetraacetate di(hydrogen sulfate(VI)) was used to examine the physicochemical properties of the resulting Ni layer and evaluate the applicability of the salt as a new additive for Watts-type baths. The Ni coatings deposited from baths containing [H2EDTA2+][HSO4-]2 were compared with those obtained from other baths. The nucleation of nickel on the electrode was proven to occur the slowest in the bath that contained the mixture of [H2EDTA2+][HSO4-]2 and saccharin compared with other baths. The addition of [H2EDTA2+][HSO4-]2 alone (bath III) generated a coating with a morphology similar to that obtained from bath I (without additives). Despite the similar morphology and wettability of the Ni-coated surfaces plated from various baths (all Ni coatings were hydrophilic with contact angles in the range of 68 to 77°), some differences in electrochemical properties were noted. The corrosion resistance for the coatings plated from baths II and IV containing saccharin (Icorr = 1.1 and 1.5 µA/cm2, respectively) and the mixture of saccharin and [H2EDTA2+][HSO4-]2 (Icorr = 0.88 µA/cm2), respectively, was similar or even better than the coating obtained from baths without [H2EDTA2+][HSO4-]2 (Icorr = 9.02 µA/cm2).

Comparison on the Ni60 Coatings Deposited by Extreme-High-Speed and Conventional Laser-Induction Hybrid Cladding Technologies: Forming Features, Microstructure and Wear Behaviors

Comparison on the Ni60 Coatings Deposited by Extreme-High-Speed and Conventional Laser-Induction Hybrid Cladding Technologies: Forming Features, Microstructure and Wear Behaviors

Investigation of copper corrosion behavior in chloride bath for nickel electrodeposition

The present study is devoted to the electrodeposition of nickel layers on copper substrates by cyclic voltammetry from chloride bath at a scan rate of 20 mV/s and at different bath temperatures between 25 and 55 °C and then after to their corrosion behavior in chloride bath. The electrochemical behavior and corrosion properties were evaluated by cyclic voltammetry, potentiodynamic and electrochemical impedance spectroscopy. While the surface analysis of nickel coating at different temperatures was conducted by optical microscopy and white light interferometer (WLI). The obtained results show that the Ni layers have been deposited successfully on the Cu substrates. It was found that raising the bath temperature to 55 °C leads to smoother, dense, compact and recovering Ni coatings with a grain size of 0.024 nm and 0.294 µm as average roughness, which is mainly due to Ni grain refinement. While the effect of increasing bath temperature leads to a decrease in the corrosion resistance of copper.

The effect of Pd and Ni coatings on hydrogen permeation experiments of as-quenched martensitic steel

Abstract Hydrogen permeation technique is a widely used testing method for the determination of hydrogen diffusion coefficient (D), which is an important parameter considering hydrogen embrittlement. A palladium (Pd) or nickel (Ni) coating is often utilised on the hydrogen detection side of the test specimens. Here, we investigate the effect of Pd and Ni coatings on hydrogen diffusion in a martensitic 500 HBW hardness low-alloy steel in the thickness range of 0.5 – 0.8 mm using a refined successive transient method and compare against an uncoated reference specimen. Both coatings yield similar average D values (6 – 6.6 × 10−7 cm2/s), but the best repeatability is achieved with Pd coating. With Ni coating, D values decrease with the increasing specimen thickness, which is partly caused by a slower hydrogen diffusion in Ni, and therefore a concentration gradient at the specimen-coating interface. The uncoated specimen has a poor transient fit, and significantly lower D (2.1 × 10−7 cm2/s) due to surface oxidation. With both coatings, the steepness of the last decay transient was highly affected by specimen thickness, and therefore the density of reversible hydrogen traps is only comparable for similar thicknesses.