Electrodeposition of CoCrFeNiAl High-Entropy Alloy Coatings: Effect of the Deposition Time on the Corrosion Resistance

Abstract In this work, CoCrFeNiAl high-entropy alloy coatings were obtained by electrodeposition in aqueous solution, using 1020 carbon steel plates as substrates. The effect of the deposition time on corrosion resistance of the coated samples was evaluated. Four deposition times were tested, 15, 20, 25, and 30 min. The corrosion behavior was studied in 3.5 wt.% NaCl solution, using electrochemical impedance spectroscopy and potentiodynamic polarization tests. The corrosion protection ability was dependent on the plating time. The coated samples exhibited passive corrosion behavior, while the uncoated steel substrate was in an active state. The stability of the passive film was higher at the deposition times of 15 min and 20 min. The passive range for the specimens obtained at a deposition time of 15 min was 3.7 times wider than at 30 min. The improved passive film stability at 15 min deposition was due to the coating morphology. Longer immersion times were detrimental to the protection efficiency, as the coating layer became more defective.