Nickel Electrolyte Research Articles

Effect of the Structure of Passive Oxide Films and Surface Temperature on the Rate of Anodic Dissolution of Chromium–Nickel and Titanium Alloys in Electrolytes for Electrochemical Machining: Part 1. Anodic Dissolution of Chromium–Nickel Steel in a Nitrate Solution

Effect of the Structure of Passive Oxide Films and Surface Temperature on the Rate of Anodic Dissolution of Chromium–Nickel and Titanium Alloys in Electrolytes for Electrochemical Machining: Part 1. Anodic Dissolution of Chromium–Nickel Steel in a Nitrate Solution

Scaling up the fabrication of wafer-scale Ni-MoS2/WS2 nanocomposite moulds using novel intermittent ultrasonic-assisted dual-bath micro-electroforming

In the scale-up fabrication process for electroformed Ni-MoS2/WS2 composite moulds, the formulation of nanosheets is critical, since the size, charge, and their distribution can largely affect the hardness, surface morphology and tribological properties of the moulds. Additionally, the long-term dispersion of hydrophobic MoS2/WS2 nanosheets in a nickel sulphamate solution is problematic. In this work, we studied the effect of ultrasonic power, processing time, surfactant types and concentrations on the properties of nanosheets to elaborate their dispersion mechanism and control their size and surface charge in divalent nickel electrolyte. The formulation of MoS2/WS2 nanosheets was optimized for effective electrodeposition along with nickel ions. A novel strategy of intermittent ultrasonication in the dual bath was proposed to resolve the problem of long-term dispersion, overheating, and deterioration of 2D material deposition under direct ultrasonication. Such strategy was then validated by electroforming 4-inch wafer-scale Ni-MoS2/WS2 nanocomposite moulds. The results indicated that the 2D materials were successfully co-deposited into composite moulds without any defects, along with the mould microhardness increasing by ∼2.8 times, the coefficient of friction reducing by two times against polymer materials, and the tool life increasing up to 8 times. This novel strategy will contribute to the industrial manufacturing of 2D material nanocomposites under ultrasonication process.

Live-current electrodeposition of Nickel on Zinc from modified Watt’s bath

ABSTRACT The zinc-nickel alloy coating has a better combination of corrosion and wear resistance compared to galvanised steel. Electrodeposition of multilayer zinc-nickel alloy coating on steel is an important industrial process. However, in the case of multilayer deposition, the plating of nickel over the zinc layer has an inherent problem owing to the corrosion of zinc in the conventional acidic nickel electrolytes. Conventionally a copper strike layer is introduced over zinc followed by nickel electroplating. The present work aims at understanding the effect of both Ni2+ ion concentration and live currents on the feasibility and quality of Ni deposition on Zn from a modified Watt’s bath such that nickel can be directly deposited on zinc without a copper strike layer. The coating appearance, thickness and roughness are found to be strongly dependent on nickel-iron concentration and the extent of live current which prevent Zn corrosion by offering cathodic protection while simultaneously depositing nickel on zinc.

Selective adsorption mechanism of copper from nickel electrolytes by tert-butyl 2-(N-octyl-2-picolyamino) acetate functionalized chelating resin: A DFT study

Exploring the selective adsorption of Cu(II) from nickel electrolytes by tert-butyl 2-(N-octyl-2-picolyamino) acetate (AMPA) functionalized chelating resin is of great implication for accurately regulating the interface interaction. In this study, based on the first-principles density functional theory (DFT), the pKa values of functional group AMPA were calculated, the H2O and Cl− were considered as ligands, and the valence bond properties were elucidated by electron localization function (ELF) and ligand field theory. AMPA is protonated to AMPAH1H2 under acidic conditions, and Cu(II) could replace protons of AMPAH1H2 and be chelated to form AMPA-Cu(II) substrate while Ni(II) cannot. An irregular octahedral configuration is formed with the coordination of H2O and Cl− based on the AMPA-Cu(II) substrate. Cl− promotes Ni(II) to replace protons of AMPAH1H2 to form [AMPA-NiCln]2−n (n ≤ 2), while Ni(II) in [AMPA-NiCln]2−n (n = 2, 3) presents poor stability and will be further replaced by Cu(II). In addition, the interaction between Cl− and Ni(II) is stronger than that with Cu(II), and [NiCln]2−n (n > 2) clusters are not conducive to being adsorbed, while the Cu(II) with weak binding ability to Cl− is selectively adsorbed. Finally, an interface interaction model of selective adsorption of Cu(II) by AMPA-based chelating resin was proposed.

A Mechanistic Investigation of Electrochemical Ozone Production Using Nickel and Antimony Doped Tin Oxide in Non-Aqueous Electrolytes

Electrochemical water splitting to produce hydrogen has attracted great interest as an environmentally-friendly renewable fuel. While cathodic hydrogen evolution (HER) is a relatively fast process that produces a valuable chemical, the anodic oxygen evolution reaction (OER) is a slow process that adds little to no economic value to water splitting.1,2 Generating a high-performance oxidizer such as ozone instead of oxygen could make water splitting more economically feasible because of the added value of ozone. However, electrochemical ozone production (EOP) catalysts are typically hindered by low current efficiencies, poor selectivity, low stability, and high energy demands, which limit the industrial application of this reaction.3,4 Further improvements in catalyst performance could be achieved by better understanding the mechanism of ozone production. Nickel and antimony doped tin oxide (Ni/Sb-SnO2, NATO) is currently reported to have the highest EOP current efficiency at room temperature. However, the mechanism of EOP on NATO electrodes has not yet been established. A primary complication when studying the mechanism of EOP using NATO electrocatalysts in water is that oxygen atoms in the ozone molecule can originate from sources other than water, such as dissolved molecular oxygen or the electrocatalyst oxide lattice.1,5,6 In this work, lattice oxygen participation in EOP is investigated by replacing water with acetonitrile, a polar aprotic solvent without oxygen atoms. Our results show that ozone can be generated in acetonitrile in similar quantities as aqueous conditions.2 These quantities are inconsistent with a 6-electron process based on calculated current efficiencies. Furthermore, the addition of small quantities of water is shown to have a negative impact on ozone generation. The origin of this impact is thought to not be mechanistic in nature. Instead, we suggest that adding water to the mixture leads to the generation of hydroxide ions which act as ozone scavengers.To our knowledge, this is the first report of electrochemical ozone production in a non-aqueous solvent. Future work will more conclusively determine the origin of oxygen atoms using isotopic labeling. Furthermore, the ability of nonaqueous solvents to stabilize reactive oxygen species and impact selectivity will be investigated. Utilizing the knowledge gained by studying ozone generation in nonaqueous solvents, it might be possible to design a better EOP system which could enhance the applicability of this reaction.(1) Lees, C. M.; Lansing, J. L.; Morelly, S. L.; Lee, S. E.; Tang, M. H. Ni- and Sb-Doped SnO2 Electrocatalysts with High Current Efficiency for Ozone Production via Electrodeposited Nanostructures. J. Electrochem. Soc. 2018, 165 (16), E833. https://doi.org/10.1149/2.0051816jes.(2) James L. Lansinga±, Lingyan Zhaob, Tana Siboonruanga, N. Harsha Attanayakea, Angela B. Leob, Peter Fatourosb, So Min Parkc, Kenneth R. Grahamc, John A. Keithb, Maureen Tang*a. Gd-Ni-Sb-SnO2 Electrocatalysts for Active and Selective Ozone Production.(3) Christensen, P. A.; Attidekou, P. S.; Egdell, R. G.; Maneelok, S.; Manning, D. A. C.; Palgrave, R. Identification of the Mechanism of Electrocatalytic Ozone Generation on Ni/Sb-SnO 2. J. Phys. Chem. C 2017, 121 (2), 1188–1199. https://doi.org/10.1021/acs.jpcc.6b10521.(4) Wang, Y.-H.; Chen, Q.-Y. Anodic Materials for Electrocatalytic Ozone Generation. Int. J. Electrochem. 2013, 2013, 1–7. https://doi.org/10.1155/2013/128248.(5) Jiang, W.; Wang, S.; Liu, J.; Zheng, H.; Gu, Y.; Li, W.; Shi, H.; Li, S.; Zhong, X.; Wang, J. Lattice Oxygen of PbO 2 Induces Crystal Facet Dependent Electrochemical Ozone Production. J. Mater. Chem. A 2021, 9 (14), 9010–9017. https://doi.org/10.1039/D0TA12277G.(6) Feng, J.; Johnson, D. C.; Lowery, S. N.; Carey, J. J. Electrocatalysis of Anodic Oxygen‐Transfer Reactions: Evolution of Ozone. J. Electrochem. Soc. 1994, 141 (10), 2708–2711. https://doi.org/10.1149/1.2059184.

Plasmon-enhanced electrochemical oxidation of 4-(hydroxymethyl)benzoic acid.

Plasmon-mediated electrocatalysis based on plasmonic gold nanoparticles (Au NPs) has emerged as a promising approach to facilitate electrochemical reactions with the introduction of light to excite the plasmonic electrodes. We have investigated the electrochemical oxidation of 4-(hydroxymethyl)benzoic acid (4-HMBA) on gold (Au), nickel (Ni), and platinum (Pt) metal working electrodes in alkaline electrolytes. Au has the lowest onset potential for catalyzing the electrooxidation of 4-HMBA among the three metals in base, whereas Pt does not catalyze the electrooxidation of 4-HMBA under alkaline conditions, although it is conventionally a good electrocatalyst for alcohol oxidation. Both 4-carboxybenzaldehyde and terephthalic acid are detected as the products of electrochemical oxidation of 4-HMBA on the Au working electrode by high-performance liquid chromatography . The electrodeposited Au NPs on indium tin oxide (ITO)-coated glass is further utilized as the working electrode for the 4-HMBA electrooxidation. With its broad absorption in the visible and near-infrared range, we show that the Au NPs on the ITO electrode could enhance the electrochemical oxidation of 4-HMBA under green and red LED light illuminations (505 and 625nm). A possible reaction mechanism is proposed for the electrochemical oxidation of 4-HMBA on Au working electrodes in an alkaline electrolyte.

Influence of 1,1-Dimethylpropargylamine on Nickel Electroplating

Nickel electroplating is widely used for decorative thin films, for better abrasion resistance and increased corrosion protection. The properties of the nickel deposit, such as its structure and morphology, can be varied by adding different organic additives to the nickel electrolyte. For example, additives such as coumarin and saccharin are used in nickel plating to generate a nickel film with uniform thickness on rough substrates.Levelling is referred to as a process of progressive reduction of surface roughness during electrodeposition. In this case, scratches or non-uniform structures on the cathode represent the initial roughness, and the result of cathodic deposition is a smooth levelled layer with reduced roughness. In this type of levelling, more metal is deposited in the grooves than on the elevated surface features. This is due to the fact that metal deposition is less inhibited in the recessed features. True levelling requires the presence of appropriate levelling agents and brighteners. A wide variety of organic compounds are used as brighteners e.g. olefinic, acetylenic and sulphur and nitrogen containing compounds.The singular and synergistic effect of the following additives on Ni electroplating was investigated and discussed in this work, such as the 1,1-dimethylpropargylamine (MPA:5 to 20 mg/L), sulfopropylated butynediol (HBOPS: 7.5 or 75 mg/L), 1-(3-sulfopropyl)-pyridinium betaine (PPS: 1.6, 3.2 or 150 mg/L), saccharin (1.5 g/L) and sodium allyl sulfonate (ALS: 1.5 g/L).Reflectance and colour measurements showed that the samples coated from nickel electrolyte containing 5mg/L MPA and 7.5 mg/L HBOPS exhibited better uniformity, gloss and good throwing power in the low current density regime when compared to the electrolytes containing other additives or without MPA. Cross section analyses of the deposits indicate that the MPA is not only acting as a strong brighter, but it also helps in levelling (Fig. 1). XRD measurements indicated the effect of the different additives on the structure of the nickel deposits.Fig. 1. Cross section of a sample deposited for 72 minutes at 2 A/dm² and 50 °C from a Ni electrolyte containing 240 g/L NiSO4 x 7 H2O, 40 g/L NiCl2 x 6 H2O, 30 g/L H3BO3, 0.5 g/L SDS, 1.5 g/L saccharin, 1.5 g/L ALS, 1.6 mg/L PPS, 7.5 mg/L HPOPS und 5 mg/L MPA Figure 1

Indirect chronovoltametric dosage of alkaline earth metals. The contribution of the chemist Ion Vatamanu to the development of electrochemical methods of analysis

The paper presents the results of a series of investigations on the indirect chronovoltametric dosing of alkaline earth metals, carried out in the Laboratory of the Analytical Chemistry at the Institute of Chemistry, currently called the Laboratory of Physicochemical Methods of Research and Analysis, conducted in 1971–1993 by the doctor of chemical sciences Ion Vatamanu. During the elaboration of the presented polarographic methods for determining the ions of alkaline-earth metals, a series of techniques were used to increase the sensitivity and selectivity of the determination. Based on two indirect polarographic methods for measuring alkaline earth metals, developed by Ion Vatamanu and coworkers and analyzed in this paper, two fundamental physicochemical principles were applied: (I) anion-induced adsorption of ligands adsorbed on the electrode surface and (II) thermodynamic determination of the optimal dosing conditions by calculating the conditional constants or the equilibrium chemical composition of complex reactant systems. The developed methods were used in the electrochemical analysis of standard alloy samples based on various metals, in the analysis of semiconductor systems, ferrous metals, nickel electrolytes, copper plating, cadmium plating, chromium plating, aluminum oxidation, wastewater analysis in galvanic baths, clays and limestones from Moldovan deposits, determination of pesticides, tanning extracts, dyes for the textile industry, etc.

Using liquid extraction to clean JSC «Kola MMC» nickel production solutions from impurities

Studies of the extractive recovery of Ca(II), Mg(II) и B(III) impurities from nickel production solutions at JSC «Kola Mining and Smelting Company» were conducted. As extraction agents, we used di-(2-ethylhexyl)phosphoric acid (D2EHPA), di-(2,4,4-trime-thylpentyl)phosphinic acid (Cyanex 272), trialkylamine (TAA), tributyl phosphate (TBP), aliphatic alcohols: octanol-1, 2-ethylhexanol and a by-product of its production – heavy product of 2-ethylhexanol distillation (TPRD). In order to assess the effect of conditions used to extract impurities from solutions, laboratory studies on the effect of aqueous phase acidity, extraction agent concentration, composition of organic impurities on their extractability were conducted. According to the research results, it was found that the optimal concentration of individual extraction agents is 20 vol.% each in the Escaid 100 solvent, and the mixture composition is 15 vol.% D2EHPA + 5 vol.% Cyanex 272 at Ca(II) and Mg(II) extraction. Individual D2EHPA predominantly extracts calcium (II): extraction of 62 % Ca(II) and 15 % Mg(II). When using Cyanex 272, the extraction of magnesium (II) predominates: extraction of 59 % Mg(II) and 20 % Ca(II). It was found that the extraction mixture has higher performance than individual extraction agents for Ca(II) and Mg(II) extraction from nickel solutions in the pH range of 3.0÷3.5, at which Ni(II) coextraction is negligible. With increasing pH values, Ca(II) extraction decreases due to the increasing extraction of nickel and the displacement of calcium by it from the organic phase. It was established that a mixture of 40 % TAA + + 60 % 2-octanone and heavy product of 2-ethylhexanol distillation exhibits high extraction ability with respect to B(III): the degree of boron extraction is 60.7 and 74.5 %, respectively. The paper provides the results of the extraction purification of the nickel electrolyte from JSC «Kola Mining and Smelting Company» with an extraction mixture in the Ni-form to exclude pH adjustment at each stage of the process. Based on the results of the studies conducted, a flowchart is recommended for obtaining pure NiSO4 solutions with a residual total B(III), Ca(II), Mg(II) and Cl– content of £0.010 g/dm3 .

Influence of heat treatment on tribocorrosion properties of Ni-B composite coatings

Various surface protection technologies, in particular, electrochemical, are used to increase the wear and corrosion resistance of steels and alloys. Composite electrochemical coatings (CEC) technology is more promising than "pure" galvanic coatings. Application of CEC increases the wear, corrosion and fatigue failure resistance of metals. Nickel often is chosen as a CEC matrix because it easily forms uniformly filled defect-free composite structures with many particles of the dispersed phase (DP).
 Physical and mechanical properties of metal coatings determine practical application of such composition. The characteristics of nickel-based CEC are: high hardness and strength, significant corrosion resistance in atmospheric environment, as well as in alkali and mild acidy environments. An effective composition coating with tribological designation can be CEC Ni-B, received in the process of electrolysis from suspension of amorphous boron in nickel electrolyte. A new composite structure of matrix filled type Ni-Ni3B is formed after heat treatment. Composition and structure of coating is determined by regimes of diffusion annealing. Ni-B coatings increase wear resistance of steel in chlorine-based environments. The influence of low-temperature thermal treatment of Ni-B CEC on steel 09Mn2Si on their tribocorrosion behavior is investigated. It is shown that the structural factor has a decisive influence on the efficiency of such friction pairs. The CEC has the least wear and the most positive compromise electrode potential after vacuum annealing at 450°C, when the initial stage of solid-phase interaction of coating components with the formation of Ni-Ni3B occurs.

ВЗАИМОСВЯЗЬ ПАРАМЕТРОВ ЭЛЕКТРООСАЖДЕНИЯ И МОРФОЛОГИИ ПОВЕРХНОСТИ НИКЕЛЕВЫХ ПОКРЫТИЙ В ПРИСУТСТВИИ ИНГИБИТОРА РОСТА

On the one hand, nickel and nickel coatings are well-studied objects in terms of their wide practical application; on the other hand, the application of various approaches to their production and structuring gives new possibilities for changing their properties. At present, the research activities related to the change in nickel physicochemical properties through nanostructuring are being carried out. Methods and techniques for producing nanostructured materials are very diverse. However, many of them are considered energy-intensive and economically unviable. The work solves the problem of obtaining nickel coatings and changing their properties through electrodeposition from aqueous solutions of electrolytes. The paper studies the effect of additives to a nickel electrolyte on the habit of crystals formed in the coating and, consequently, the nickel coating morphology. The authors used sodium, potassium, and calcium chlorides in the same molar concentration to be additives. During the electrodeposition of coating samples, the substrate nature and the electrolysis regimes changed. The deposition was carried out in the stationary mode of electrodeposition within one or two stages of electrolysis. The authors studied the obtained samples by scanning electron microscopy methods using X-ray diffraction analysis. The study identified that chlorides can significantly change the coating surface morphology. Depending on chloride concentration and deposition regimes, the surface morphology of nickel coatings changes from the three-dimensional cone-shaped structures to the lamellar habit. Chlorides allow forming crystals with pentagonal symmetry as well. The addition of chlorides affects the growth of crystals in certain crystallographic directions (111), which may be the result of their inhibitory effect. The obtained nickel coatings have a regular microrelief.

Получение сульфата никеля из полупродуктов Кольской ГМК

The article studies the possibilities of obtaining pure nickel sulfate from the filtrate of the cobalt purification of the nickel electrolyte of JSC "Kola MMC". Methods of purification of nickel solutions using sedimentation and extraction methods that remove impurities of sodium, chloridones, micro-impurities of calcium and magnesium are considered.

Room-Temperature Electrochemical Healing of Structural Steel through Pulsed Plating and Tailored Electrolyte Chemistry

Low-carbon steel is a widely used structural metal that, when fractured, can be repaired with high temperature processes such as arc welding. There are many applications, however, that would benefit from a room-temperature repair process which maintains the steel microstructure and prevents adjacent materials and electronics from overheating. We seek to enable effective room-temperature healing of steel using electrochemistry by understanding how ion transport and electrolyte chemistry influence growth and strength in fractured steel wires repaired with nickel electrodeposition. Experiments and simulations show that pulsed electroplating mitigates diffusion-limited growth to enable smooth and dense nickel deposits that have 4x higher adhesion to steel than nickel deposited by potentiostatic electroplating. We also investigate the effect of various nickel electrolyte chemistries on nickel-steel adhesion and the recovery of strength in healed steel. By combining pulsed electroplating with judicious use of electrolyte chemistry, fully fractured steel wires could be repaired to achieve up to 69% of their pristine strength.Finally, we propose a simple geometric model to estimate the energy and time requirements of electrochemical healing across length scales. Our model shows that if crack width can be minimized, over eight hundred 10-mm steel reinforcing bars (commonly used in construction) could be healed in under one minute using only one smartphone battery (5,000 mAh).This work is the first demonstration of electrochemical healing of a metal other than nickel (see our prior work: Hsain and Pikul, Adv. Funct. Mater. 29, 2019) and opens the possibility of healing a variety of structural metals using electrodeposition. With its low energy and time requirements, as well as its effective recovery of strength, electrochemical healing can be used to minimize weight in aerospace structures, extend the service life of structural parts, and more efficiently employ scarce resources in energy-constrained systems or remote environments.

Comparative investigation of different types of nickel foam samples for application in supercapacitors and other electrochemical devices

Nickel foam is widely used as a current lead/current collector and the basis of nickel hydroxide electrodes for various electrochemical devices – batteries, hybrid supercapacitors, devices for electrocatalytic oxidation of organic substances. The characteristics of commercial samples of nickel foam produced by Novomet-Perm (Russian Federation) obtained by electroless and then electrochemical nickel plating and Linyi Gelon LIB Co Ltd (China) obtained by electroless nickel plating were studied. The nature of passivity was determined by forming model samples of electrochemical and electroless nickel on a steel base. For the passive sample, activation was carried out by applying a layer of electrochemical nickel from an impact nickel plating solution. Activated, non-activated samples of nickel foam, as well as model samples, were studied by the methods of cyclic voltammetry and galvanostatic charge-discharge cycling in the supercapacitor mode. Comparative analysis of Chinese-made and Russian-made nickel foam samples showed significant passivity of the former – in cyclic voltammetry, the activity was 4.8 times lower, with galvanostatic charge-discharge cycling – 2.59 times lower. It was suggested that high passivity was determined by the fact that the sample consisted of Ni-P or Ni-B alloy. This assumption was proved by the method of natural simulation. The electrochemical activity of electroless nickel was 1.25 times lower than that of electrochemical nickel (according to cyclic voltammetry data) and 1.58 times lower (according to galvanostatic cycling data). For the first time, Chinese-made nickel foam (electroless nickel) was activated by applying a layer of electrochemical nickel from an impact nickel electrolyte. The high activation efficiency was shown as follows – on the cyclic curve, the specific current of the anodic peak increased 8.71 times, and with galvanostatic cycling, the increase in specific capacity was from 1.73 times (at i=120 mA/cm2) to 4.84 times (at i=20 mA/cm2)

Stabilization of the Computation of Stability Constants and Species Distributions from Titration Curves

Thermodynamic equilibria and concentrations in thermodynamic equilibria are of major importance in chemistry, chemical engineering, physical chemistry, medicine etc. due to a vast spectrum of applications. E.g., concentrations in thermodynamic equilibria play a central role for the estimation of drug delivery, the estimation of produced mass of products of chemical reactions, the estimation of deposited metal during electro plating and many more. Species concentrations in thermodynamic equilibrium are determined by the system of reactions and to the reactions’ associated stability constants. In many applications the stability constants and the system of reactions need to be determined. The usual way to determine the stability constants is to evaluate titration curves. In this context, many numerical methods exist. One major task in this context is that the corresponding inverse problems tend to be unstable, i.e., the output is strongly affected by measurement errors, and can output negative stability constants or negative species concentrations. In this work an alternative model for the species distributions in thermodynamic equilibrium, based on the models used for HySS or Hyperquad, and titration curves is presented, which includes the positivity of species concentrations and stability constants intrinsically. Additionally, in this paper a stabilized numerical methodology is presented to treat the corresponding model guaranteeing the convergence of the algorithm. The numerical scheme is validated with clinical numerical examples and the model is validated with a Citric acid–Nickel electrolyte. This paper finds a stable, convergent and efficient methodology to compute stability constants from potentiometric titration curves.

Zinc-nickel alloy coatings: electrodeposition kinetics, corrosion, and selective dissolution. A review

A review of the literature is devoted to the patterns of the electrodeposition of zinc-nickel alloys including the kinetics of cathodic reduction of zinc, nickel, and zinc-nickel alloys in ammonium chloride, sulphate, and glycinate deposition electrolytes. We studied the data on the effectiveness of the corrosion resistance of zinc-nickel coatings and summarised the principal patterns of selective dissolution of the Zn-Ni alloys. The role of the addition of glycine to an ammonium chloride deposition electrolyte was determined in the modification of the morphological and anticorrosive properties of the coatings.

Electrodeposition of Nickel/Graphene Oxide Particle Composite Coatings: Effect of Surfactants on Graphene Oxide Dispersion and Coating Performance

The dispersibility of graphene oxide particles (GOs) in nickel electrolytes is critical for its uniform incorporation in the nickel matrix during the electrodeposition process. In this study, we study the fundamental interaction of surfactants and nickel ionic strength for uniform and stable incorporation of GOs in nickel electrolytes and their effect on coating performance. The results indicate that the non-ionic surfactant Polyethylene glycol (PEG) has the optimal dispersibility of GOs in nickel electrolyte, followed by the cationic surfactant Cetyltrimethylammonium bromide (CTAB) and the anionic surfactant Sodium dodecyl sulfate (SDS). It is also noted that the increasing nickel ionic strength would deteriorate the stability of GOs, attributing to the generation of cross-linking of high strength divalent nickel ions with dispersed graphene oxide. The electrodeposited coatings show that more incorporation of graphene oxide in the coating is achieved when the PEG surfactant is used, which leads to an increased hardness by 146% and a decreased friction coefficient by 72.7% under low nickel sulfamate concentration (200 g l−1), compared to pure nickel coating. Eventually, the study shows that higher nickel ionic strength would deteriorate the performance of the coatings, while the selection of proper surfactant can compensate for it.

Hybrid functional materials forming the metal structure with optimal imperfection for storage of hydrogen in hydride form

The paper investigates the samples of Ni–B and Ni–In composites in the form of films synthesized by an electrochemical method having a 3high degree of defectiveness and shows the electrochemical processes for their preparation, in which the experimental data of the influence doping additions of boron and indium on the hydrogen permeability of synthesized electrochemical complexes based on nickel Nix-By-Hzand Nix-Iny-Hz are given. It is shown that by creating traps (structural, impurity) for hydrogen by introducing additional elements into the metal structure or by changing the structure (intermetallides), also by other methods, the hydrogen solubility of the metal can be changed to a greater or lesser extent depending on the technical requirements. Ni–B samples were obtained in the sulfamate nickel electrolyte using boron compounds of the class of higher polyhedral borates Na2B10H10. The use of nanoforming boron additives provides measured hydrogen content in Nix-By-Hz samples about of 600 cm3/100 g. Nickel-indium composites were obtained by electrolytic deposition on copper substrates (0,05 mm thick), with electrolyte composition: NiSO4 × 7H2O = 140 g/L; Na2SO4 × 10H2O = 20 g/L; and In2(SO4)3 which concentration varied from 1 g/L to 12 g/L. Variations in the amount of In2(SO4)3 ensured the production of Ni–In composites with different component ratios. The obtained data made it possible to select the optimal mode of deposition of Ni–In plating in the In2(SO4)3 electrolyte. In order to determine the effect of each of the electrodepositing parameters on the properties of the samples, only one parameter varies: either the cathode current density or the concentration of indium in the electrolyte. The samples of different concentrations of In are synthesized and studied. Their phase composition was determined. X-Ray phase analysis reveals in the Ni–In composites synthesized from electrolytes with In2(SO4)3 concentration of more than 2 g/L, a phase corresponding to the intermetallide η-In27Ni10.For the first time in the practice of studying sorption, electrochemical composites Nix-Iny, including subsequent thermal desorption of hydrogen, are studied by implanting deuterium into the samples. It is demonstrated spectra of deuterium thermal desorption from Ni70In30Dx composites, which allowed determining the temperature ranges of desorption of ion-implanted deuterium depending on the dose of implantation. It is confirmed that a Ni70In30 composite capable of retaining doped deuterium (hydrogen) has been obtained. It is shown that it is permissible to obtain samples of a Nix-Iny-Dz composite with a deuterium content of up to 2 at. D/at. Met., that corresponds to 5,3 wt% (for composites of this composition).

Improving the structural properties and corrosion behaviour of electroless deposited Ni-P-Zn coatings on mild steel for advanced processes

Hydrated crystal of ZnSO4·7H2O was co-deposited with NiSO4·6H2O, and NaH2PO2·H2O processed electrolyte to develop a ternary phase electroless coating on mild steel for advanced application. The coating was produced in an aqueous nickel electrolyte solution with zinc at a temperature of 90 ℃ and varying time conditions between 20 and 50 min. The effects of the developed coatings on microstructure and physical properties were investigated using scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), and optical microscopy. The corrosion characteristics of the coatings examined in 0.5 M H2SO4 and 3.5% NaCl were analyzed using linear potentiodynamic polarization technique. The microstructure revealed that the constituent deposited on the steel. A more uniformly distributed crystallite with minimal pores was observed at 20 min of Ni-P-Zn coating, while the tiniest film was observed at 50 min of the coating without crack. There was also a fully compact grain within the intermetallic matrix of the coating due to the synergetic effect of the electrolyte constituent with the strengthening phase of Zn7Ni4P2, Zn2Ni5P, and Zn3Ni. Corrosion study established that Ni-P-Zn exhibits significant corrosion resistance at the optimum time within the examined environments with little SO42- and Cl- ions.

Electrochemical treatment of waste water from nickel in galvanic production

In the production of metal coating by electroplating, wastewater containing the metal ions is used. The paper presents the study results of cleaning waste water of nickel after electroplating. Wastewater treatment was implemented in an electrodialysis plant. The initial wastewater contained from 20 to 80 mg/l of nickel II. Experimental results obtained by studying the electrodialysis extraction of nickel from wastewater of electroplating plants, indicate that the cleaning process is influenced by such factors as the effluent treatment time, the current load on the electrodialyzer, the initial metal concentration in the effluent. The increase in voltage in the electrodialysis plant leads to an increase in the treatment efficiency. So after six hours of processing, the processing rate during nickel extraction increases from 39 to 66.5% with an increase in voltage from 40 to 100V. Along with cleaning wastewater of nickel electrolyte, the electrodialysis method allows obtaining concentrates of this electrolyte containing from 260 to 1230 mg/dm3 of nickel and suitable for use in the electroplating process.