No abstract

A method has been developed which permits the use of an insoluble anode to electrodeposit cobalt by the addition of a sufficient amount of an electrochemically active substance such as vanadium pentoxide to the cobalt sulfate plating solution. In the absence of such additions, formation of Co3+ ions and cobalt oxide false(Co2O3false) at the platinum anode results during plating. The effects of the addition of vanadium pentoxide on the electrode process during plating have been investigated through the analyses of various electrolysis products as a function of additive concentration and plating time. The results show that besides cobalt deposition, vanadium ions of lower oxidation state (V++, V+++, VO++ ) are formed at the cathode and these ions seem to be responsible for the reduction and suppression of Co3+ ions and the oxide at the platinum anode. It has also been observed that the concentration of the added electrochemically active substance changed very little, indicating no incorporation of vanadium with the deposit during plating. The mechanical properties of the deposits prepared using an insoluble anode are compared with those obtained using a soluble anode.

The solubilities of γ‐ and α‐Al2O3 particles have been investigated in dilute H2SO4 and in watts‐type plating electrolytes of cobalt and nickel. The effects of the presence of Al3+ ions in the plating solutions on the properties of electrodeposits of cobalt and nickel have also been studied. The results show that γ‐oxide is more soluble than α‐oxide, the solubility increases with decreasing solution pH and increasing temperature. Aluminum contents of up to 0.04 weight per cent (w/o) in cobalt and 0.02 w/o in nickel were found and the room temperature yield strength values increased to about 40% for cobalt and 20% for nickel deposits. The effects on the yield strength values of normalCo‐Al2O3 and normalNi‐Al2O3 alloys due to the presence of Al3+ ions in their respective plating electrolyte‐oxide suspensions are also discussed.