Zinc-nickel Alloy Research Articles

Electrodeposition of Zinc-Nickel Alloys from Ethylene Glycol for Corrosion Protection

Zn rich ZnNi alloys electrodeposition have recently attracted the attention of researchers due to their interesting corrosion properties [1]. In particular, alloys containing Ni in the 15 - 25 % range find application in a number of industrial fields, like automotive and constructions. ZnNi is normally electrodeposited from aqueous solutions, in which plating takes place following a typical anomalous mechanism [2]. In the last few years, however, new deposition approaches have been attempted to improve ZnNi plating performances. Specifically, III generation deep eutectic solvents comprising choline chloride have been tested [3].The present work investigates the use of non-aqueous ethylene glycol based electrolytes for the deposition of Zn rich ZnNi alloys. The use of ethylene glycol as solvent introduces many advantages with respect to aqueous solutions: low oxygen contamination, high deposits purity and no pH dependance [4]. ZnNi codeposition was studied employing cyclic voltammetry and layers were deposited under potentiostatic control. Deposition potential was varied and its influence on final composition and morphology was determined. Addition of an additive (NH4Cl) to enhance surface morphology was attempted as well [3]. Phase composition was investigated using XRD to determine the possible presence of a metastable γ-ZnNi phase, which has already been observed in the case of ZnNi plated from alkaline aqueous solution [5]. Finally, corrosion behavior of layers obtained from ethylene glycol was assessed and compared with equivalent coatings deposited from commercial aqueous solutions.[1] M. Gavrila et al.; Surface and Coatings Technology, 123 (2-3), 164-172 (2000)[2] G. Roventi et al.; Journal of Applied Electrochemistry 30 (2), 173–179 (2000)[3] S Fashu et al.; Transactions of Nonferrous Metals Society of China 25 (6), 2054-2064 (2015)[4] G. Panzeri et al.; Electrochimica Acta 271 (1), 576-581 (2018)[5] S. Ieffa et al.; Transactions of the IMF 94, 321-324 (2014)

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.

Zn composite corrosion resistance coatings: What works and what does not work?

Corrosion is one of the most significant contributors to structural degradation in process industries. It causes process equipment failure, which can led to severe safety issues. One approach to address this concern is to provide a preventive barrier-coating to equipment. Due to its superior reductive property, zinc is usually employed as a sacrificial anode in conventional corrosion-resistance methods. Nickel is also used to both mechanically strengthen the barrier and improve overall corrosion resistance; therefore, zinc, zinc-nickel alloys, and zinc-nickel-oxide composite coatings are commonly employed for anti-corrosion purposes. The complexation of zinc and nickel ions by agents (citrate, acetate and EDTA) can stabilize the electrodeposition bath and extend the pH of Ni(OH)2 and ZnO precipitation to improve corrosion resistance in the resultant coating. This paper reviews the challenge with these type of coatings and presents progress in Zn and Zn-Ni composite corrosion resistance coatings co-deposited with Al2O3, TiO2, ZrO2, SiO2, and Fe2O3 as means of corrosion control to reduce the probability of process equipment failure due to corrosion, which will improve the overall safety and reliability of processing equipment.

Synergetic Effects of Temperature and Perpendicular Magnetic Field on Zn-Ni Alloy Electrodepositing Process

The zinc-nickel alloys were electrodeposited on stainless steel substrates during a chloride acid bath. The electroplating processes were investigated under a moderate perpendicular magnetic flux at uncommon temperatures. The coatings obtained were characterized by scanning microscopy (SEM) including EDX and X-ray diffraction (XRD). Chronopotentiometric curves were additionally implemented for electrochemical analysis. Structural analysis revealed that the obtained alloys consisted of a mix of the homogeneous phase γ-Ni3Zn22 and α-Zn-Ni at 70 ºC. The alloys variations observed within the chemical composition, crystallographic phases and morphology of the alloys. It is often explained particularly, by the progressive hydrogen reaction and therefore the evolution of the adsorbed intermediate species. The synergetic effect was significant at 70 ºC within the 1T field, including the appearance of normal co-deposition.

Progress in Electrodeposition of Zinc and Zinc Nickel Alloys Using Ionic Liquids

Zinc (Zn) and zinc–nickel (Zn–Ni) electrodeposition has been widely used in many industries, such as automotive and aerospace, for corrosion protection of steel components owing to their excellent corrosion resistance. Conventional zinc and zinc–nickel electrodeposition is performed in different types of aqueous baths (acid and alkaline). Such electrolytes suffer from certain drawbacks such as hydrogen gas evolution, low coulombic efficiencies, and environmental toxicity. Electrodeposition of Zn and Zn–Ni alloys from ionic liquids has gained significant attention in aerospace and automotive sectors owing to the different environments they provide for electrodeposition. This paper reviews the progress in deposition of zinc and zinc-nickel alloys in non-aqueous systems, especially ionic liquids. In addition, the challenges and technological developments associated with the Zn and Zn–Ni deposition on different substrates and the factors that need to be considered while electroplating at an industrial scale are discussed.

Electroplating and Physicochemical Properties of Zinc–Nickel Alloy Coatings from Ammonium Oxalate Electrolytes

Electroplating of zinc−nickel alloy coatings (3–16 at % Ni) on Type 17G1S-U steel from ammonium oxalate baths is studied. The effects that the ratio of alloy components has on the coating’s corrosion resistance and structure and the electroplating kinetic parameters are revealed. Applying zinc–nickel alloy coatings leads to a nearly sevenfold decrease in the corrosion rate compared to zinc-only coatings. The microhardness of high-alloy nickel coatings increases by a factor of 1.8 compared to their low-alloy zinc–nickel counterparts.

Electrodeposition of Zinc–Nickel Coatings from Glycine-Containing Ammonium-Chloride Electrolyte

The kinetic regularities of the electrodeposition process of alloyed zinc–nickel coatings from an ammonium-chloride electrolyte solution have been studied. The effect of the addition of aminoacetic acid on the mechanism of the electrodeposition process, current efficiency, surface morphology, chemical and phase composition of the synthesized coatings has been established. The process of electrochemical deposition of alloys of Zn–Ni system from ammonium-chloride electrolyte is complicated by the diffusion transport of ions in the liquid phase of the electrolyte solution, while the kinetic stage of charge transfer is irreversible. The addition of aminoacetic acid does not change the mechanism of the electrodeposition process, however, it increases the current efficiency of the target process by approximately 6%, presumably due to a decrease in the contribution of the hydrogen evolution reaction to the overall rate of the cathodic process. The addition of glycine improves the surface morphology of the synthesized coatings by reducing the roughness and denser packing of the nuclei of the growing phase, and also increases the nickel content in the alloy by an average of 4 at %, but does not affect the phase composition of the coatings, which remain heterogeneous and consist of γ-phase of Ni2Zn11 and Zn. A quantitative assessment of the anticorrosive efficiency of electrodeposited zinc–nickel alloys is carried out depending on the presence of aminoacetic acid in the electrolyte solution. It is found that the introduction of glycine into ammonium-chloride electrolyte of deposition leads to the refinement of the corrosion potential and a noticeable decrease in the corrosion current density of the Zn, Ni-alloy coating in aqueous solution of 3.5% NaCl. This indicates an increase in the resistance of the electrochemically synthesized protective film material to corrosion damage. The optimal conditions for the electrochemical synthesis of morphologically homogeneous anticorrosive zinc–nickel coatings are selected.

Electrochemical technology for the formation of heterogeneous metal structures with increased corrosion resistance

Research into corrosion resistance of multilayer materials obtained by the method of potentiostatic pulse electrolysis was conducted. The purpose of the work was to select materials for the creation of multilayer steel coatings with high corrosion resistance, as well as to develop technology for their formation. The formation of galvanic coatings was carried out in stationary and potentiostatic pulse electrolysis modes. The study of corrosion resistance was carried out by accelerated methods in solutions simulating the marine environment. Corrosion resistance of samples made of St3 steel coated with nickel and zinc-nickel alloys of different compositions when using various electrolysis modes was studied. It has been experimentally proved that the potentiostatic mode of pulse electrolysis allows the formation of galvanic coatings with a zinc-nickel alloy of various compositions from one electrolyte. Based on the study of electrode potentials of coatings in various media, the composition of the outer and inner layers of a multilayer heterogeneous structure was substantiated. It was experimentally proved that the formation of multilayer coatings on the surface of steel could significantly increase the protective properties of these coatings. It was theoretically justified that the materials of the layers should have different values of electrode potentials, and the inner layer should have a more negative value of the potential than the outer one has.

Formation and Cathodic Reduction of Taurine Complexes with Zinc and Nickel(II)

The stability constants of zinc and nickel(II) complexes with taurine have been determined at 25°C and ionic strength values of 0.5; 1.0; and 1.5 (KNO3). The values of thermodynamic stability constants have been calculated. The processes of electrodeposition of zinc–nickel alloys on the 08KP-grade steel from electrolytes with taurine additive and physicochemical properties of coatings have been studied. The effect of the alloy components' ratio on chemical composition and microstructure of the coatings has been demonstrated.

Decontamination of waste water in adrag-out recovery bath of zinc-nickel alloy electrodeposition

Decontamination of waste water in adrag-out recovery bath of zinc-nickel alloy electrodeposition

Pulse Electroplating of Zinc/Nickel Alloy from a Deep Eutectic Solvent (DES)

Electrodeposition of metal coatings such as nickel, zinc, tin, chromium and cadmium for the purposes of corrosion protection has been a core interest of the electrochemical community for more than one hundred years. Cadmium has been a favourite for military and aerospace applications because of the combination of good corrosion protection and lubricity. However, cadmium salts are very toxic and hazardous and so the use of cadmium coatings is now proscribed in all but the most demanding of applications. Alternatives to cadmium coatings have included aluminium and more recently zinc nickel alloys. The latter is more accessible via aqueous methods but requires rigorous control and monitoring of bath conditions in order to maintain the composition and quality of the coating. An alternative to aqueous electrolytes is a derivative of ionic liquids that feature eutectic mixtures of quaternary ammonium salt and hydrogen bond donor. These have become known as deep eutectic solvents (DSE). Here we have used a DES to produce coherent and adherent coatings of zinc nickel alloy in an electrochemical study and in pre-commercialisation scale-up trials. In a digital controlled pulse-plating method, alternative forward (deposition) and reverse (stripping) currents, are applied to adjust the deposit composition and morphology, as has been demonstrated in film plating from aqueous electrolytes. This report focuses on pulse-plating γ-Zn11Ni2 alloy from a eutectic mixture of choline chloride (ChCl) and ethylene glycol (EG), also known by the commercial name of Ethaline. The effect of pulse shape and frequency on deposit morphology and crystal structure were analysed and compared with coatings derived from constant current (DC) plating methods, through Hull cell tests, XRD, and SEM/EDX measurement. The deposit composition is shown here to be dependent on the average current density, the surface morphology is not sensitive to the pulse frequency, while dendritic growth is shown to be suppressed by pulsed current. We show that the crystal grain size can be controlled according to the pulse shape and frequency. By choosing a certain shape and frequency, the pulse-plating in the DES can provide improved coating qualities and improved process control. Additionally, we have extended the laboratory investigation to pre-commercial scale-up trials with a commercial electroplating company (EC Williams, UK). This project is funded by an Innovate UK action and is entitled Cadmium Replacement Using Pulse-Plating and Ionic Liquids (CRUPPAIL). Barrel-plating trials using pulse and reveres pulse methods on small components such as screws have given even adherent coatings, Figure. The combination of pulse methods and DES electrolyte give a levelling effect, Figure (a), and good throwing power in confined geometries, Figure (b). Figure: Scanning electron micrographs of Zinc Nickel alloy (85:15%) deposited using DES and pulse-plating on mild steel substrates, (a) sheet, (b) screws. Figure 1

Effects of novel additives for zinc-nickel alloy plating

The development of alternative coating material is important for the corrosion life of metals. Improving the corrosion resistance and decorative appearance of zinc-nickel coatings is gaining importance. Related physical properties can be provided by using various chemicals. Tetraethylamine, triethanolamine, gelatin, and p-aminobenzenesulfonic are the chemicals used in this study to evaluate corrosion resistance and decorative appearance.

USING ZINC-NICKEL ALLOY IN THE ZINC DEPOSITION TECHNOLOGY

Introduction. More negative potential of zinc coatings provides effective protection of the steel substrate from corrosion damage. To increase the chemical resistance to corrosion processes, zinc coatings are necessarily post-treated, i.e. by chromate treatment. The disadvantages of the latter are the use of toxic compounds of Cr (VI) and removing a significant layer of zinc coating (up to 2 μm). The aim of the study was to substantiate the choice of electrolyte for zinc electrodeposition mostly meeting modern requirements, and to replace the chromate film with a thin layer of zinc-nickel alloy. Materials and research methods. The measurements were carried out in a tree-electrode cell using a PI-50.1 potentiostat with a saturated silver chloride reference electrode. The values of the electrode potentials in the graphs are shown by this electrode. Zinc coatings were deposited from chloride, ammonina and alkaline electrolytes with two versions of organic additives. Zinc-nickel alloy coating was prepared from an ammonina-glycinate electrolyte. Results. Chloride and ammonium electrolytes are characterized by high current outputs, close to 100%, in almost the entire range of current densities from 1 to 4 A/dm2. The current efficiency decreases with current density increasing in alkaline electrolytes. It is due to the greater uniformity of metallic coatings. The throwing power in the studied electrolytes was estimated usingHull cell with a sectional cathode. The ratio of the maximum and minimum weight increments in individual sections of the cathode in indicates a higher throwing power of alkaline electrolyte. Due to the high protective properties of zinc-nickel alloy coatings, it is proposed to obtain a thin layer (0.5-0.7 µm) of the zinc-nickel coating from the ammoniz-glycinate electrolyte instead of chromate passive film during the process of zinc electrodeposition.

Role of the newly synthesized brightener in modification of surface properties of Zn-Ni alloy electrodeposited on steel substrate

In the present study, a new brightener was synthesized by condensation of salicylaldehyde and cysteine hydrochloride (SC). To examine the influence of SC on the nucleation mechanism of Zn-Ni alloy, electrodeposition, cyclic voltammetric and chronoamperometric studies were carried out. The model of Schariffker and Hills was used to analyze current transients which explained the electrocrystallization process of Zn-Ni alloy. It is revealed that Zn-Ni electrocrystallization process in presence of SC is regulated by instantaneous nucleation mechanism. The corrosion studies were done for the bright and dull zinc-nickel alloy coatings in 3.5 wt.% NaCl solution, using potentiodynamic polarization and electro­chemical impedance spectroscopic techniques. The phase structure, surface morphology and brightness of the deposit were characterized by means of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and reflectance studies. These studies revealed the role of SC in producing a bright Zn-Ni alloy coating on mild steel substrate and also showed its improved corrosion resistant nature.

Evolution of microstructure of zinc-nickel alloy coating during hot stamping of boron added steels

The environmental regulations and safety requirements have enhanced the requirement of advanced and ultra-high strength steels. The hot forming process is known to deliver ultra-high strength steels. The boron added steels are heated beyond the austenitization temperature and subsequently deformed and quenched to form deformed components having fully martensitic structure. However, the bare steel suffers from oxidation and decarburization if no coating is applied. The conventional zinc based coatings like, galvanised, galvannealed are not suitable as zinc or iron-zinc phases melt at high temperature of austenitization and give rise to microcrakcs. The present work deals with a new zinc based coating system formed by a combination of electrodeposition and galvanising incorporating nickel in the coating. The coating microstructure is comprised of different nickel-zinc phases having difference in melting points as well. The evolution of coating microstructure at different soaking temperature and time is studied. The coating microstructure and compositions are observed by optical and confocal laser scanning microscope along with Secondary Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS). The different coating phases undergo melting and there is homogeneous nucleation of iron-rich solids in the coating. The composition and phase fractions of iron and zinc-rich phases are verified from ThermoCalc calculations. The coating transforms to complete iron-rich solid after 300 s of soaking at the austenitizing temperature. However, the initial zinc content largely determines the final fraction of zinc-rich liquid phases. The hot deformation study shows microcrack free regions at different areas of the hat sections.

KINETICS OF ELECTRODEPOSITION OF ZINC-NICKEL ALLOY FROM SULFATE-GLYCINATE ELECTROLYTE

Kinetics of electrodeposition of a zinc-nickel alloy from the acid sulfate-glycinate electrolyte and the properties of the formed coating have been studied depending on the composition of the electrolyte and the deposition mode. Chronoamperometric studies of the electrodeposition of the zinc-nickel alloy made it possible to establish that at polarization potentials of -1.00 -1.05 V relative to the CSE, processes on the electrode proceed with diffusion control. Changing the potentials to the region of more negative values leads to kinetic difficulties. The formation of the zinc-nickel alloy from the sulphate-glycinate electrolyte is affected by the concentration of the nickel salt. The process polarization, crystallization overvoltage, the amount of nickel in the alloy depends on its content in the solution. The maximum crystallization overvoltage corresponds to the NiSO4 content in the electrolyte in the amount of 0.12-0.14 mol/l. Large partial densities of the electroreduction current of nickel during the formation of the Zn-Ni alloy correspond to the same range of concentrations. It was found that with the content of nickel sulphate more than 0.16 mol / l, the amount of nickel in the precipitate decreases. During electrodeposition of the alloy, the pH of the near-electrode layer increases as a result of hydrogen evolution. It is assumed that with the cathode current density of more than 10 mA/cm2, the formation of the zinc-nickel alloy occurs with the participation of neutral and electronegative complexes. Determination of the protective ability of samples in a 3 % NaCl solution using both chronovoltamperometry and impedance spectroscopy showed that samples with a nickel content of 14.4 % obtained in the solution with a nickel sulfate concentration of 0.12-0.14 mol/l are characterized by maximum corrosion resistance.

Hydrogen Embrittlement for High Strength Steel Treated with Zinc and Zinc-Nickel Alloy Electroplating from a Sulfate Bath and Hydrogen Permeability

Hydrogen Embrittlement for High Strength Steel Treated with Zinc and Zinc-Nickel Alloy Electroplating from a Sulfate Bath and Hydrogen Permeability

Corrodibility and Adherence of Reinforced Concrete Rebars Electroplated with Zinc and Zinc-Nickel Alloys

Reinforced concrete is the main structural material used in the world in the construction of bridges, roads and commercial and residential buildings. One effective method for preventing corrosion of steel reinforcement is the application of galvanic coatings to the reinforcement itself. The present study evaluated the performance of three groups of reinforcing steel bars (black steel, used as a reference and rebars electroplated with Zinc and Zinc-Nickel alloys) to corrosion and adherence to the concrete matrix. For the analysis of corrosion, the specimens were subjected to two different accelerated corrosion tests: salt spray exposure and wet and dry semi-cycles. The corrosion potential was measured for the qualitative monitoring of the corrosion process and the corrosion rate was estimated. In order to evaluate the steel-concrete adherence, the pullout test was used, in accordance with RILEM-CEB-FIP. The results showed that Zinc and Zinc-Nickel coatings increased the durability of the reinforcing bars and the accelerated corrosion test of wetting and drying cycles proved to be more aggressive compared to the salt spray method to evaluate the corrosion process in the reinforced concrete specimens. Additionally, galvanized reinforcement reduced adherence to the concrete matrix.

CONDITIONS OF ZINC-NICKEL ALLOY FORMATION FROM AMMONIA-GLYCINATE LOW-CONCENTRATED ELECTROLYTE

Introduction. Zinc-nickel alloys coatings are considered to replace cadmium coatings. The corrosion resistance of the zinc-nickel alloy depends on the phase composition of the coating. Thus, the alloy coatings with nickel content of 8–14 wt. % (mainly the γ-phase) are characterized by corrosion resistance 5 times greater than zinc coatings. In turn, the composition and structure of the coatings is determined by the conditions of their production, primarily by the type of electrolyte and electrolysis modes. The aim of the work is to determine the effect of the low concentration ammonium glycinate electrolyte composition on electrode processes during the formation of coatings with a zinc-nickel alloy. Materials and research methods. The kinetics of electrode processes on zinc and nickel samples with surface area from 1 to 5 cm2 in ammonia-glycine electrolyte was studied by analyzing polarization dependencies using a PI-50.1 potentiostat with three electrode cell. A saturated silver chloride electrode was used as a reference electrode, and the potentials are given according to this electrode. Voltammograms were obtained at a potential scan rate of 50 mV/s. The pH value of the electrolytes was monitored using CT-6020A pH meter. Results. The effect of pH value of a mixed ammonium-amino acid electrolyte on the kinetic regularities of electrode processes during the nickel and zinc codeposition was determined by the polarization method. The shape of the polarization dependences of alloy deposition allows suggesting the presence of two limiting stages – electrochemical and diffusion. When pH of the electrolyte increases the alloy deposition occurs with greater overvoltage on both nickel and zinc electrodes. The zinc codeposition with nickel begins at potentials more negative than –1.2 V. Thus, it is possible to obtain zinc-nickel alloys with the necessary protective characteristics by changing the conditions of electrolysis.

Electrochemical behaviour and analysis of Zn-Ni alloy anti-corrosive coatings deposited from citrate baths

Zinc-Nickel alloy coatings have been widely used to improve the corrosion resistance of steels. Electrodeposition of zinc-nickel alloy films on a steel plate under various deposition conditions is studied. The effects of plating variables such as bath composition, pH and current density on the coating composition, morphology and corrosion property have been systematically investigated. The zinc and nickel ions in plating baths are stabilized using complexing agent potassium citrate. Increasing the molar concentration of potassium citrate extends the pH of nickel hydroxide and zinc oxide precipitation. The morphological properties and crystalline phase structure of the deposited alloy coatings are examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The analyses reveal that the coatings deposited from citrate bath contain γ-NiZn3 and γ-Ni2Zn11 alloy phases. These phases improve the corrosion resistance of the steel plate. Electrochemical behaviour analyses of the Zn-Ni film illustrated by electrochemical impedance spectroscopy (EIS) measurement revealed that the sample (a) deposited from 0.0326M citrate bath at acidic pH shown higher impedance modulus than non-citrate bath coated samples, which improved anti-corrosive properties of the coatings. This study confirms that uniform Zn-Ni coating with smaller grain sizes has better anti-corrosive properties.