Study of the effect of new brightener on Zn–Ni alloy electrodeposition from acid sulphate bath

Abstract

The electrodeposition of Zn-Ni alloy from acid sulphate bath was carried out in presence of a brightener, such as condensation product of vanillin and serine (VS). The cyclic voltammetry and chronoamperometry techniques were used to study the nucleation mechanism process, while polarization and electrochemical impedance spectroscopic (EIS) techniques for corrosion studies. The model of Scharifker and Hills was used to analyze the current transients and it revealed that Zn-Ni electrocrystallization process in presence of VS, under the studied conditions, is governed by progressive nucleation process. Corrosion studies showed that bright Zn-Ni alloy coatings exhibited higher corrosion resistant nature. The Zn-Ni layer obtained in presence of VS shows smooth morphology with smaller grain sizes and higher percentage of reflectance signals.

Electrochemical studies of sol-enhanced Zn–Ni–Al2O3 composite and Zn–Ni alloy coatings

“…Basavana et al [24,25] investigated the electrodeposition and nucleation process of Zn-Ni alloys from chloride and sulfate baths in the presence and absence of some brighteners such as the condensation products of vanillin, serine and hexamine. Their results showed that the Zn-Ni electro-crystallization process was governed by the deposition potential and type of brighteners.…”

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

“…The second (A 2 ) and the third (A 3 ) anodic peaks at potentials -0.76 V and -0.54 V respectively, correspond to dissolution of zinc from δ-phase and γ-phase respectively. The fourth anodic peak (A 4 ) at nobler potential (-0.27V) corresponds to the dissolution of nickel from ,  and  phases [3,9,15]. Thus, the voltammetric response gives information regarding the characteristics of the components of Zn-Ni alloy and the structure of deposited phases.…”

“…As elucidated above, the amount of nickel in the deposit is much lower than in the plating bath solution. Also, the concentration of nickel ions near the cathode surface should be maintained at a constant value during the entire electroplating process [9]. The nucleation process of Zn-Ni deposit is always associated with release of hydrogen which is seen from equation (8).…”

“…Brighteners are often added into the plating bath solution of common metals such as zinc, nickel or cobalt to improve properties of the final deposit and to make the surface more durable, compact and uniform for better performance in terms of corrosion protection [3,8]. Brighteners are usually added into the electrolytic bath at very low concentration, in parts per million, but their presence in the bath promotes formation of smooth and shiny coatings [9].…”

Effect of benzaldehyde on the electrodeposition and corrosion properties of Ni–W alloys

“…Additives are extensively used in plating baths because of their low toxicity, easy handling, small required amounts, and easier effluent treatment after degradation [3]. Organic molecules adsorbed onto the cathode surface can affect the rate of charge-transfer reactions and the mechanism of electrocrystallization [4]. Hence, the adsorption of these organic molecules at the metal-solution interface is of significant interest in surface science and can markedly change the corrosion resistance properties of metals [5].…”