PROCEDURE FOR ELECTROLYTIC MOLYBDENUM COATING FROM WATER SOLUTION Russian patent published in 2010 - IPC C25D3/54 

FIELD: metallurgy.

SUBSTANCE: procedure consists in preparing water solution of molybdenum blue wherein ratio of molar concentration of pentavalent molybdenum to general molar concentration of reduced sodium molybdate is in interval (0.3-0.7):1, in preparing electrolyte for application of molybdenum coating and in application of coating. Water solution of molybdenum blue is produced in a two-chamber electrolyser with non-soluble electrodes and a cation membrane. Cathode space is filled with solution containing 3.5-4.5 g/l of sodium molybdate, 98.0-196.0 g/l of sulphuric acid and water, while anode space is filled with solution of sulphuric acid. Coating is applied from electrolyte containing 500 ml/l of molybdenum blue, 17.8-107.1 g/l of sodium citrate, and 26.4-198.0 g/l of ammonium sulphate at 15-25°C, cathode density of current 30-70 A/dm², and with usage of two non-soluble anodes. Also, 75-85 % of anode current is supplied to the first anode, while 15-25 % - to the second.

EFFECT: production of compact, shiny galvanic sediments of metallic molybdenum with black tint up to several mm thickness.

4 cl, 1 tbl, 4 dwg, 6 ex