Evaluation of Formic Acid and Cyclohexylamine as Additives in Electrodeposition of Zn Coating

The Zn coatings obtained through electrodeposition are used to protect steel substrates from corrosion. In general, organic additives are added to the deposition bath in order to improve deposition characteristics such as corrosion resistance, hardness and deposition efficiency. Despite the literature presenting various organic additives' effects on Zn coating properties, there is no analysis of compounds with free electron-containing radicals, such as formic acid and cyclohexylamine. This manuscript presents an analysis of the effect of adding a mixture of formic acid and cyclohexylamine on the deposition flow efficiency, corrosion resistance, hardness, roughness, and micro-structure of Zn coating on carbon steel AISI 1020. The corrosion resistance evaluation was performed by potentiodynamic polarization, determined by polarization resistance and weight loss tests. Morphology and electrodeposited microstructures were analyzed using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). Results showed that corrosion resistance in the 0.5 mol/L NaCl solution of Zn coatings increases with the addition of the mixture of formic acid and/or cyclohexylamine, with a synergic effect resulting in higher corrosion resistance than with either additive alone.