Electrodeposition of Metal Molybdenum from Electrolytes Containing Hydrofluoric Acid

N. D. Ivanova^a, S. V. Ivanov^b, E. I. Boldyrev^a, and O. A. Stadnik^a

^a Vernadskii Institute of General and Inorganic Chemistry, Ukrainian Academy of Sciences,
ul. Borshchagovskaya 210, korp. 33, Kiev-58, 03058 Ukraine

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^b National Aviation Institute, Kiev, Ukraine

Received January 28, 2005

Abstract — The effect of hydrofluoric acid on the cathodic reduction of molybdate ions is studied. It is shown that the mechanism of this process is determined by the acid concentration: in a concentration range below 25g/l the intermediate products of molybdate-ion reduction, namely, black or colored deposits containing molybdenum with the average valence of 3.6–4 are formed on the cathode. For the concentration above 50 g/l, molybdate ions are completely reduced and form at the cathode dense light metallic coatings with a thickness of 3–5 µm and good adhesion to the substrate. The addition of hydrofluoric acid prevents polymerization of molybdate ions.

PACS numbers: 81.15.Pq