TESTING THE ROLE OF METAL HYDROLYSIS IN THE ANOMALOUS ELECTRODEPOSITION OF NI-FE ALLOYS

With the objective of testing several models of the ''anomalous codepo sition'' (ACD) encountered in the electrodeposition of nickel-iron all oys, the effects of bath pH and complexing agents on the composition o f deposits were examined. When the pH of the ''base line'' bath was in creased from 3.0 to 5.0, the Ni/Fe mass ratio of the deposit increased (i.e., the deposition became less anomalous). The presence of tartrat e ion in the bath produced a slight decrease in the Ni/Fe of the depos it. This complexing agent complexes ferric ion and thus prevents its p recipitation but has little interaction with ferrous ion or nickel ion under the electrodeposition conditions examined. The addition of ethy lenediamine to the bath produced a significant increase in the Ni/Fe m ass ratio. This complexing agent does not interact significantly with ferric ion or ferrous ion under the test conditions. None of these obs ervations are consistent with the Dahms and Croll model of ACD. The ef fects of pH and tartaric acid on the deposit composition are consisten t with the predictions of the Grande and Talbot model and the Matlosz model. The effect of ethylenediamine is not consistent with the Grande and Talbot model, but may be interpreted within the framework of the Matlosz model and the Hessami and Tobias model.