Electrodeposition of Molydenum Alloys from Aqueous Solutions

Abstract

Nickel‐molybdenum, cobalt‐molybdenum, and iron‐molybdenum alloys have been electrodeposited from aqueous solutions containing sodium molybdate, the sulfate of the codeposited metal, sodium citrate, and ammonium hydroxide. Typical baths were made up with 0.3 M/1 of the codepositing metal sulfate, 0.3 M/1 of sodium citrate, varying amounts of sodium molybdate, and ammonium hydroxide to pH about 10.5. The maximum amount of molybdenum in the electrodeposited alloys depends on the alloying metal. When a typical bath was used, nickel alloys were found to contain up to 20% molybdenum, cobalt alloys contained up to 40% molybdenum, and iron alloys contained about 50% molybdenum. The cathode current efficiency in the above cases ranged from 75–85% for the nickel‐molybdenum bath, 50–60% for cobalt‐molybdenum, and 10–20% for iron‐molybdenum. The effects of pH, concentration, temperature, and cathode current density on cathode current efficiency and alloy composition were studied.