Electroplating of CoFe Alloys from Aqueous Acetate Baths

SUMMARYFilms of CoFe alloys have been deposited galvanostatically onto a steel electrode from solutions containing CO(CH3 COO)2 FeSO4 and CH3COOH. The cathodic polarization, the deposition efficiency and the composition of the films were determined as a function of current density and composition of the bath. The codeposition shows an anomalous behaviour with Fe (the less noble) being the preferentially deposited metal. This observation is interpreted in terms of suppression of Co (the more noble) deposition by a surface iron hydroxide precipitated during codeposition. The efficiency improves with increasing current density but decreases with increasing acetic acid concentration. The morphology of the deposits was examined by SEM. In most cases, smooth dense and uniform deposits with microcracks were observed.