Electrochemical properties of electrodeposited nanocrystalline cobalt and cobalt-iron alloys in acidic and alkaline solutions

Nanocrystalline Co and CoFe with varied iron contents ranging from 5 to 25 wt% Fe were electrodeposited from a sulfate bath. The average grain sizes of the coatings obtained were measured using Scherrer equation and calculated to be in between 16 and 65 nm. Electrochemical corrosion behavior of electrodeposited nanocrystalline cobalt (Co) and cobalt-iron (CoFe) alloys was investigated in both acidic (0.1 M H₂SO₄) and alkaline solution (0.1 M NaOH). This study investigates the corrosion behavior of electrodeposited CoFe alloy coatings using polarization tests, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy techniques. The nanocrystalline Co and CoFe showed active behavior for all alloy coatings in acidic condition, while an active-passive-transpassive behavior was seen for all coatings in alkaline condition.