Electrodeposition Behavior, Physicochemical Properties and Corrosion Resistance of Ni-Co Coating Modified by Gelatin Additive

The effect of gelatin on the microstructure, composition and electroplating mechanism of Ni-Co coating synthesized from sulfate media onto carbon steel substrate was investigated using AFM analysis, SEM/EDS and Electrochemical Quartz Crystal Microbalance (EQCM) coupled with chronopotentiometric measurements. The deposition of gelatin in the coating matrix was found to lower the mass of Ni-Co layers. Moreover, the adsorption of this additive seemed to inhibit the initial nucleation of the Ni-Co electrodeposition, showing homogeneous surface and smaller crystallites. Furthermore, the corrosion performance was studied in 3% NaCl solution by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). After a long immersion into chloride solution, Ni-Co-Gelatin (Ni-Co-Gel) coating showed a good stability and a better corrosion resistance. Therefore, the presence of gelatin additive impacted the crystal size, corrosion resistance and Ni-Co deposits morphology.