Zn-Ni Deposition Research Articles

Effect of Condensation Product on the Electrochemical Behaviour and Corrosion Resistance of Zn and Zn-Ni Deposits

Electrodeposition of Zn and Zn-Ni deposits were performed on steel substrates under various conditions from acid sulphate baths in presence of condensation product of 3, 4, 5-trimethoxybenzaldehyde and serine (TMBS). The electrochemical behavior of deposits was studied by polarization and electrochemical impedance techniques. The Zn-Ni-bright deposits obtained from the acid sulphate bath at 4 Adm-2 showed a lower corrosion current (Icorr) and a less negative corrosion potential (Ecorr) compared to Zn-dull, Zn-Ni-dull and Zn-bright deposits. The surface morphology and phase structure of the deposits was studied by Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis.

Electrodeposition Based Preparation of Zn–Ni Alloy and Zn–Ni–WC Nano-Composite Coatings for Corrosion-Resistant Applications

Zinc (Zn) is one of the five most widely consumed metals in the world. Indeed, more than 50% of all the zinc produced is used in zinc-galvanizing processes to protect steel from corrosion. Zn-based coatings have the potential for use as a corrosion-resistant barrier, but their wider use is restricted due to the poor mechanical properties of Zn that are needed to protect steel and other metals from rusting. The addition of other alloying elements such as Ni (Nickle) and WC (Tungsten Carbide) to Zn coating can improve its performance. This study investigates, the corrosion performance of Zn–Ni coating and Zn–Ni–WC composite nanocoatings fabricated on mild steel substrate in an environmentally friendly bath solution. The influence of WC nanoparticles on Zn–Ni deposition was also investigated. The surface morphologies, texture coefficients via XRD (X-ray diffraction), SEM (Scanning Electron Microscopy), and EDS (Energy-dispersive X-ray spectroscopy) were analyzed. The electrochemical test such as polarization curves (PC) and electrochemical impedance spectroscopy (EIS) resulted in a corrosion rate of 0.6948 Å/min for Zn–Ni–WC composite nanocoating, and 1.192 Å/min for Zn–Ni coating. The results showed that the Zn–Ni–WC composite nanocoating reduced the corrosion rate by 41.71% and showed an 8.56% increase in microhardness compared to the hardness of the Zn–Ni coating. These results are augmented to better wettable characteristics of zinc, which developed good interfacial metallurgical adhesion amongst the Ni and WC elements. The results of the novel Zn–Ni–WC nanocomposite coatings achieved a great improvement of mechanical property and corrosion protection to the steel substrate surface.

Electrodeposition of ZnNi Alloys from Choline Chloride/Ethylene Glycol Deep Eutectic Solvent and Pure Ethylene Glycol for Corrosion Protection.

The present work follows the trend to develop non-aqueous electrolytes for the deposition of corrosion resistant ZnNi alloys. It investigates the use of the choline chloride/ethylene glycol (1:2 molar ratio) eutectic mixture and of pure ethylene glycol as solvents for ZnNi electroplating. The electrochemical behavior of Zn and Ni is investigated via cyclic voltammetry, and potentiostatic ZnNi deposition is performed. Ni content is found to be precisely tunable in the 10–20% wt range, which presents the highest industrial interest for corrosion protection. ZnNi coatings obtained are characterized from the morphological and phase composition point of view. Evidence of the formation of a metastable γ ZnNi phase is observed for both choline chloride/ethylene glycol and pure ethylene glycol. Finally, potentiodynamic corrosion tests are performed to assess their corrosion properties.

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.

Influence of temperature and potential range on Zn-Ni deposition properties formed by cyclic voltammetry electrodeposition in chloride bath solution

AbstractThis paper describes the study of electrodeposition process by cyclic voltammetry for Zn-Ni bimetallic coating on the X52 carbon steel substrate. Prior to the deposition at the bath temperatures of 25°C, 40°C, and 60°C, investigations were carried out to find the optimum potential range for zinc-nickel coatings with respect to the Ag/AgCl reference electrode. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) was used for surface morphology and elemental composition studies. The corrosion rate of the deposits was studied using the linear polarization resistance (LPR) method by immersing the samples (with and without coating) into 3.5% NaCl solution for 24 h. SEM and EDX results showed that the bath temperature has affected the formation of the microstructures and composition of coating. In addition, micro-cracks, nickel content, mobility of ions and compactness of microstructure increased by raising the bath temperature used for electrodeposition. The corrosion rate obtained from the LPR method can be correlated with the SEM/EDX analysis. The coating deposited at the temperature of 60°C including more content of nickel and micro-cracks led to lower corrosion resistance compared to the coating deposited at the bath solution temperatures of 25°C, 40°C, and non-coated X52 steel. Based on the results, the Zn-Ni coating deposited on the X52 steel substrate in the bath solution at 40°C presented the best performance due to more suitable achievements of microstructure compaction, composition, microcracks, and corrosion resistance observations.

Electrochemical studies of 2-aminopyridine on nanocrystalline Zn[sbnd]Ni alloy electrodeposition

Nanocrystalline alloy exhibit superior characteristics that are not typically found in conventional coating and its formation is usually induced by additives. However, the influence mechanism of additives on the electrodeposition process was rare to be investigated, especially in the molecular scale. In this study, nanocrystalline ZnNi alloy was electrodeposited from the bath containing 2-aminopyridine as a novel additive and the influence mechanism of 2-aminopyridine in contrast with triethylenetetramine, vanillin and coumarin on electrodeposition of nanocrystalline ZnNi alloy was studied by the combined theoretical and experimental studies. It is found that intermediate Znad+ can catalyze the reduction of Zn2+ and Ni2+. The electrodeposition mechanism of ZnNi alloy is unchanged both without and with 2-aminopyridine, however an increased overpotential is observed with 2-aminopyridine, which is related to its strong adsorption on electrode surface. Triethylenetetramine increase the ZnNi deposition overpotential by complexing with metal ions. Vanillin and coumarin is achieved mainly by their spot adsorption of oxygen atoms on electrode surface. While synergistic surface adsorption of the amine group and adsorption ring plane in 2-aminopyridine maximizes the ZnNi deposition overpotential, leading to the formation of nanocrystalline ZnNi alloy.

Theoretical and experimental studies of 2,2-bipyridine for nanocrystalline zinc-nickel deposition

A nanocrystalline Zn-Ni alloy with an average grain size of 25 nm was electrodeposited from an alkaline bath with 2,2-bipyridine. An effective approach using electrochemical experiments and quantum chemical calculations was employed to investigate the effect of 2,2-bipyridine on the process of Zn-Ni deposition. Quantum chemical calculations indicate that the ring structure (especially nitrogen atoms) in 2,2-bipyridine is the most active reactive site for its adsorption. 2,2-bipyridine can form effective and stable surface adsorption on the electrode surface by sharing electrons between the ring structure and Zn-Ni atoms. The addition of 2,2-bipyridine does not change the single-step two-electron transfer mechanism with the diffusion-controlled process of Zn-Ni growth. However, better corrosion resistance and wear resistance of nanocrystalline Zn-Ni alloys is obtained with 2,2-bipyridine, which can be associated with the rapid formation of hydrophobic nature on nanocrystalline Zn-Ni alloys, and its smoother surface as well as higher hardness and lower friction coefficient, respectively.

Ni-P/Zn-Ni compositionally modulated multilayer coatings – Part 1: Electrodeposition and growth mechanism, composition, morphology, roughness and structure

The Ni-P/Zn-Ni compositionally modulated multilayer coatings CMMCs were electrodeposited from a single bath by switching the cathodic current density. The composition, surface morphology, roughness, layers growth pattern as well as the phase structure of deposits were extensively studied via SEM, EDS, AFM and XRD analysis. Effects of bath ingredients on the electrodeposition behavior were analyzed through cathodic linear sweep voltammetry. Although the concentration of Zn2+ in bath was 13 times higher than Ni2+, the Zn-Ni deposition potential was much nearer to Ni deposition potential rather than that of Zn. Addition of NaH2PO2 to the Ni deposition bath considerably raised the current density and shifted the crystallization potential of Ni to more nobble values. Codeposition of P with Zn-Ni alloy lead to crack formation in the monolayer that was deposited in 60 mA/cm2. However, the cracks were not observed in the Zn-Ni layers of multilayers. Zn-Ni layers in CMMCs exhibited a three-dimensional pattern of growth while that of Ni-P layers was two-dimensional. Also, the Ni-P deposits tends to fill the discontinuities in Zn-Ni layers and performed leveling properties and lowered the surface roughness of Zn-Ni layers and CMMCs. Structural analysis demonstrated that Ni-P layers were amorphous and the Zn-Ni layers exhibited crystallite phase of Zn11Ni2. Thus, the Ni-P/Zn-Ni CMMCs comprised of alternate layers of amorphous Ni-P and nanocrystalline Zn Ni.

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

Anticorrosive coatings are a useful approach for protecting steel structures/machinery against corrosion. Electrodepositions of zinc and zinc–nickel alloy films on steel substrates under various conditions from baths containing potassium citrate were studied. The effects of electroplating variables such as bath composition and current density on the coating composition, morphology, corrosion and mechanical properties were systematically investigated. The electrochemical and mechanical behaviour of Zn–Ni deposits obtained at 60 mA cm−2 from the citrate bath exhibited a lower corrosion current (Icorr) and a less negative corrosion potential (Ecorr) compared to pure Zn and Zn–Ni alloy coatings from the non-citrate bath. The crystallite size of the Zn–Ni coating deposited from the citrate bath was 35.40 nm, and the Ni content of the coating was 8.3 wt%. The morphological properties and crystalline phase structure of the alloy coating were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The topographical structure of the coatings was analyzed by atomic force microscopy (AFM). The dominant γ-NiZn3 (815) and γ-Ni2Zn11 (330) (631) plane orientations in the zinc–nickel alloy films improved the corrosion resistance. Zn–Ni films with smaller grain size and uniform coating had an increased impedance modulus and improved corrosion resistance.

Studies on electrochemical deposition of novel Zn–Mn–Ni ternary alloys from an ionic liquid based on choline chloride

Ternary Zn–Mn–Ni alloy coatings were electrodeposited for the first time from a choline chloride based ionic liquid with the aim of collecting properties of binary Zn–Mn and Zn–Ni alloys into one alloy system. The effect of electrodeposition potential on the composition and corrosion performance of the obtained ternary Zn–Mn–Ni deposits was investigated and contrasted with the characteristics of Zn–Mn and Zn–Ni deposits. Cyclic voltammetry revealed that the deposition of ternary Zn–Mn–Ni alloys behaved differently from the deposition of binary Zn–Mn and Zn–Sn alloys and that Mn deposition takes place at positive potentials in the Zn–Mn–Ni electrolyte than in the Zn–Mn electrolyte due to the presence of Ni2+ ions in the electrolyte. X-ray diffraction studies showed that the Zn–Mn–Ni ternary alloys consist of a lattice of Zn (with Mn and Ni imbedded inside) at low electrodeposition potentials and MnZn(with Ni imbedded inside) phase at high electrodeposition potentials. Chemical composition analysis show that the Mn content in the ternary Zn–Mn–Ni alloy increased with increase in electrodeposition potential, whereas Zn and Ni contents are suppressed. The corrosion tests results indicate that through addition of Ni into the Zn–Mn binary alloy, the Zn–Mn–Ni alloy tailored are more corrosion resistant than the Zn–Mn binary alloy whilst the passivation behavior is still preserved.

Electrodeposited Zn-Ni alloys as promising catalysts for hydrogen production-Preparation, characterization and electro-catalytic activity

Nano-crystalline Zn, Ni and Zn-Ni alloys were prepared as electro-deposited layers on copper substrates. The obtained materials were characterized morphologically and chemically by XRD and scanning electron microscopy, SEM, coupled with EDAX analysis. The electrochemical properties were investigated in KOH solutions by polarization measurements, cyclic voltammetry and EIS techniques. Special emphases were subjected to the hydrogen evolution reaction, HER, on the electrodeposited materials. It was found that the electro-deposited Zn-Ni alloy cathodes possess high catalytic activity for hydrogen evolution in alkaline solutions, which was found to depend on the microstructure and surface morphology of the deposited layer. The high electro-catalytic activity was attributed to the increased surface area of the deposited layers and the number of active sites therein. The increase of the Ni content up to ≈50 at% in the deposited cathode leads to a decrease in the hydrogen evolution overpotential. The highest rate of hydrogen evolution was recorded on Zn-Ni deposits with ≈50 at% Ni. The electrochemical polarization measurements were confirmed by impedance experiments, and the experimental impedance data were fitted to theoretical data according to a proposed model for the electrode/electrolyte interface.

Theoretical Calculations and Electrochemical Behaviors of Additives in DMH-Based Alkaline Bath for Nanocrystalline Zn-Ni Electrodeposition

A combined approach using quantum chemical calculations, molecular dynamic simulations and electrochemical experiments was employed to investigate the effect mechanism of additives on Zn-Ni alloy deposition process. Results show that in addition to ethylenediamine, vanillin, coumarin and saccharin with ring structure can form effective adsorption on metal surface. The MD simulations confirm this theoretical prediction that the ring structure of vanillin can strongly adsorb on metal surface. This can be further verified by experimental analysis. Compared to other additives, larger cathodic polarization with decreased nanocrystalline grain size is obtained with vanillin. Therefore, vanillin is predicted as the most promising additive due to its relatively higher EHOMO, smaller ΔE values and larger overpotential. The effect of vanillin on the controlling process of the reaction and nucleation mechanism of Zn-Ni alloys was also studied. The presence of vanillin does not change three-dimensional instantaneous nucleation with mixed controlled process of Zn-Ni deposition. However, the increase of overpotential is observed form the bath with vanillin compared with basic bath. This can be associated with the adsorption behavior of vanillin on metal surface, especially the adsorption of its ring structure. This has been evidenced by quantum chemical calculations and molecular dynamic simulations.

Influence of formic acid on the microstructure and corrosion resistance of Zn–Ni alloy coatings by electrodeposition

In this study the effect on the deposition efficiency and corrosion resistance of Zn–Ni electrodeposits after the addition of formic acid (0.03 to 0.53mol/L) to the plating bath is investigated. The corrosion resistance was evaluated in an aerated solution of 2.0mol/L NaOH and 0.5mol/L NaCl using weight loss tests and electrochemical measurements, potentiodynamic polarization curves and electrochemical impedance spectroscopy measurements. The addition of formic acid to chemical bath enhanced the corrosion resistance of the Zn–Ni deposit in both solutions. Above 0.07mol/L formic acid added to the solution, which corresponds to pH3.0, the corrosion rate does not vary significantly. Improved corrosion resistance, by adding 0.07mol/L formic acid, was found in deposits obtained from chemical bath with the same pH. The addition of formic acid to the chemical bath of the Zn–Ni deposit produces an enhancement in the efficiency of galvanostatic deposition when the pH of the bath is maintained at approximately pH3.0. It was observed that the addition of formic acid changes the structure of the Zn–Ni deposit due to the presence of the Ni5Zn21 intermetallic phase.

Effect of Triethanolamine Addition in Alkaline Bath on the Electroplating Behavior, Composition and Corrosion Resistance of Zn-Ni Alloy Coatings

Zn-Ni alloy coatings were electrodeposited on low carbon steel substrate using a cyanide-free alkaline bath containing tetraethylenepentamine (TEPA) and triethanolamine (TEA) as complexing agents for Ni2+cations. Effect of TEA/Ni2+molar ratio on electrodeposition behavior, micromophology, Ni content and corrosion resistance of coatings were studied by means of SEM/EDS, polarization curve and electrochemical impedance spectroscopy (EIS), respectively. It was found that the deposition potential and elecctrochemical impedance of the cathode sample during the electrodeposition was influenced by the TEA/Ni2+molar ratio (TNmr) in the bath. The deposition potential shifts negatively and the impedance rises with increasing TNmrup to 2. The nickel content in Zn-Ni deposit was varied in a range from 16.81 to 19.04 wt.%. The dependence of cathodic current efficiency and depositing velocity of the coating on TNmrof plating bath were also determined. A fine-grained and smooth-faced coating was obtained at TNmr=2, which exhibited the highest corrosion resistance in 3.5% NaCl environment.

Evaluation of the effect of deposition bath glycerol content on zinc–nickel electrodeposits on carbon steel

Zn–Ni electrodeposits have been used to improve the corrosion resistance of carbon steel substrates in several applications, mainly in the aeronautical, oil, gas, and automotive industries. The use of component compounds that increase deposition efficiency and corrosion resistance has attracted growing interest. In this study, the effect of glycerol bath content (to a concentration of 0.34mol/L) in bath deposition was analyzed. The deposition efficiency was analyzed by galvanostatic and potentiodynamic deposition, and the corrosion resistance was estimated with electrochemical tests, and mass loss measurements. The deposits were characterized by X-ray fluorescence, X-ray diffraction, and scanning electron microscope. The results indicate that there is a significant increase in the deposition efficiency and corrosion resistance when using glycerol concentrations up to 0.07mol/L. For glycerol concentrations between 0.14 and 0.34mol/L, there is a decrease in the deposition efficiency, and these concentrations do not result in a clear increase in the corrosion resistance of the Zn–Ni deposit. Analysis of the effect of deposition bath glycerol on the deposition efficiency and corrosion resistance of a Zn–Ni alloy indicates that this effect is related to the morphology of the deposit. The addition of glycerol to the deposition bath solution deposition results in grain refinement and the formation of a more compact deposit.

Chemical, physical and morphological characterization of ZnNi films electrodeposited on 1010 steel substrate from acid baths containing polyalcohol

ZnNi alloy electrodeposition on a 1010 steel electrode in boric-acid baths containing sorbitol, mannitol or glycerol was investigated by cyclic voltammetry. Electrodeposits obtained galvanostatically were characterized by SEM, EDS and XRD. It was found that in baths containing sorbitol or mannitol, the deposition current density (jd) was reduced, but in none of the baths was the initial deposition potential affected. SEM images of deposits revealed that the boric-sorbitol and boric-mannitol complexes refine the grain, even at high jd. XRD patterns of the ZnNi deposits produced at jd=50mAcm−2, in ZnNi1 bath and in ZnNi1 bath contained sorbitol or mannitol, indicated that the films were formed mainly of Zn and γ1 phases. To ZnNi2 baths contained glycerol the films were formed of γ and γ1 phases. The Ni content in the deposits produced in the bath without polyalcohol or containing glycerol increased from ~5 to 19wt.% with increasing jd. With sorbitol or mannitol, there was a smaller rise from ~7 to 10wt.% Ni. Thus, ZnNi deposits providing sacrificial protection can be obtained in baths with or without polyalcohol. The linear polarization method showed that ZnNi alloy deposited from baths contained polyalcohol have greate Rp.

Zinc-Nickel Codeposition in Sulfate Solution Combined Effect of Cadmium and Boric Acid

The combined effect of cadmium and boric acid on the electrodeposition of zinc-nickel from a sulfate has been investigated. The presence of cadmium ion decreases zinc in the deposit. In solution, cadmium inhibits the zinc ion deposition and suppresses it when deposition potential value is more negative than V. Low concentration of CdSO4reduces the anomalous nature of Zn-Ni deposit. Boric acid decreases current density and shifts potential discharge of nickel and hydrogen to more negative potential. The combination of boric acid and cadmium increases the percentage of nickel in the deposit. Boric acid and cadmium.

Study of the effect of mannitol on ZnNi alloy electrodeposition from acid baths and on the morphology, composition, and structure of the deposit

A boric acid bath for ZnNi alloy electrodeposition was developed with mannitol as additive. The deposition process was investigated by cyclic voltammetry. It was found that the current density decreased, due to adsorption of a boric–mannitol complex and/or changes in the morphology, but the initial deposition potential was not affected. At deposition potentials more negative than −1.20 V, the current efficiency obtained was high (80–85%) in all baths studied. The addition of mannitol to the bath led to the formation of the best ZnNi deposits, composed of coalesced globular grains smaller than ~1 μm in diameter. Also, all of the ZnNi deposits studied consisted of γ, γ1, and Pt3Zn phases. The Ni content in the ZnNi deposits produced in the presence of mannitol increased from 6 to 10 wt% only in the range −1.26 to −1.40 V. It is suggested that the ZnNi deposits produced in these baths probably offer sacrificial protection to the substrate.

ZnNi alloy electrodeposition from acid baths containing sorbitol or glycerol and characterization of ZnNi deposits

The influence of sorbitol or glycerol on the electrodeposition of ZnNi alloys and on the morphology, composition and structure of the ZnNi deposits was investigated. The highest current efficiency (CE), around 90%, was obtained in the presence of glycerol in the potential range from approximately −1.30 V to −1.40 V, while in the presence of sorbitol or absence of either polyalcohol the CE was 82–85%, for the same potential range. Scanning electron microscopy (SEM) analysis showed that ZnNi deposition at −1.26 V or −1.40 V from a bath with sorbitol led to the formation of more compact deposits than with glycerol. Energy dispersive X-ray spectroscopy (EDS) analysis showed that the Ni content in the deposit obtained in the presence of sorbitol remained in the range of 7–9.5 wt% Ni, over a large range of deposition conditions. On the other hand, ZnNi deposits with variable Ni content (5.5–19.5 wt% Ni) were obtained from baths with glycerol or without either polyalcohol, by shifting the deposition potential. All ZnNi deposits showed uniform distribution of the elements Zn and Ni. X-ray analysis of ZnNi deposits obtained from plating baths with and without polyalcohol’s at −1.26 and −1.40 V presented the γ, γ1 and Pt3–Zn phases.

Development of compositionally modulated multilayer Zn–Ni deposits as replacement for cadmium

Compositionally modulated multilayer (CMM) Zn–Ni deposits were electrodeposited from single acidic bath (pH = 4.7) by using a potentiostatic sequence. The Zn and Ni composition in the alloy was tailored as a function of distance from the steel substrate. X-ray diffraction studies of the deposit showed the presence of γ-phase with a composition of Ni 5Zn 21. The corrosion properties of modulated multilayer coatings were studied in 5% NaCl solution using electrochemical corrosion techniques. The polarization resistance of the deposits varied as a function of Ni content between 1700 and 3440 Ω. CMM Zn–Ni with 20 wt% Ni exposed in ASTM B117 salt spray test did not show any red rust formation after 400 h.