Electrodeposition of cobalt-iron alloys in pulsed current from electrolytes containing organic additives

A pulsed electrodeposition method is applied to the preparation of magnetic CoFe films. Common additives are used as leveling and brightening agents in the plating bath. In the present work, the effects of some organic additives such as saccharin, or such as phtalimide that contains no sulphur element are investigated on the cobalt-iron electrodeposition using potential-times transient curves. The composition, morphology and grain size of the deposits are examined by scanning electron microscopy and the corrosion properties are characterized by voltammetry. It is found that the electrocrystallization process of cobalt-iron is sensitive to organic additives nature. Experimental results indicate that even if the molecular structure of the phtalimide is quite similar to saccharin, the behavior during the electrodeposition of CoFe is not the same. The presence of sulfonamide groups seems to be responsible for the best anti-corrosion properties of the CoFe deposit. Moreover, the addition of organic additives such as saccharin decreases the iron deposition rate through a surface blocking and solution chelating process. However, pulsed electrodeposition with saccharin is shown to be an interesting technique to deposit bright and smooth CoFe films. A high Ton value for pulse plating parameter is advised.