ELECTRODEPOSITION OF THIN-FILMS OF NICKEL-IRON .1. EXPERIMENTAL

The effects of the removal of dissolved oxygen and the addition of ferric ion in the presence and absence of 0.4M B(OH)3 on the anomalous codeposition of iron and nickel from 0.5M NiSO4 and 0.1M FeSO4 solutions at pH 3 on a rotating disk electrode at a speed of 100 rpm were studied. The eff ect of sparging the solution containing boric acid with argon, which reduced the dissolved oxygen concentration to 1.2 ppm, was an increase in the iron content of the deposit by at least 10 weight percent for the range of current densities applied. With the addition of boric acid to a sparged bath, the rate of nickel deposition decreased and the rate of iron deposition increased. The hydrogen evolution rate was independent of both boric acid addition and dissolved oxygen concentration. In general, the addition of 0.005M ferric sulfate to the sparged plating baths affected the rates of nickel deposition and hydrogen evolution, whereas the rate of the iron deposition was unaffected.