The Electrodeposition of Cobalt-Tungsten-Molybdenum Alloys from Aqueous Citrate Solutions

The electrodeposition f cobalt-tungsten-molybdenum alloys is described. The aque-ous plating bath was prepared from sodium tungstate, sodium molybdate, cobalt sul-fate, and citric acid. The pH of the solution was adjusted by the addition of either ammonium hydroxide or dilute sulfuric acid. A Hull cell and regular plating pro-cedures were used to determine optimum bath concentrations and electrolysis condi-tions. It was found that 't bath containing0.23 mole per liter of cobalt sulfate, a total of 0.23 mole per l iter of sodium tungstate and sodium molybdate (W:Mo mole ratio of 7:3), and 0.31 mole per liter of citric acid gave satisfactory performance. When this plating solution was adjusted to pH 4 and maintained at 25 ~ electrolysis at 5 amp/dm 2gave a cathode deposit containing 66 per cent cobalt, 21 per cent molybdenum, and 13 per cent tungsten with a cathode current efficiency of 73 per cent