Malic acid pathway of constructing high-performance Ni anticorrosive coatings using supercritical-CO2 electrodeposition

We presented the fabrication of nickel (Ni) coatings from malic acid-supported Ni electrolyte (M/Ni-E) as an alternative for boric acid by supercritical-CO 2 (SC–CO 2 ) electrodeposition. The surface roughness, morphology, and crystal phase structure of the prepared coatings were analyzed with an atomic force microscope (AFM), field emission scanning electron microscope (FESEM), and X-ray diffraction (XRD) techniques. Corrosion resistance was evaluated through standard electrochemical methods such as linear polarization and electrochemical impedance spectroscopy (EIS) techniques with 1 M HCl solution. Based on the FESEM, AFM , and XRD results, the film prepared by a malic acid-supported electrolyte exhibits a compact coating with smaller grains (21.6 nm) and lower surface roughness ( RMS = 7.59 nm). The corrosion resistance of the film prepared with M/Ni-E by SC-CO 2 method shows a higher corrosion resistance of 570 Ω/cm 2 . Thereby, malic acid is suggested as a suitable replacement for boric acid and SC-CO 2 electrodeposition process as an environmental-friendly approach.