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Electrodeposition of Platinum-group Metals.
Schlain-D; McCawley-FX; Smith-GR
NTIS: PB 272 913 :22 pages
The Bureau of Mines investigated methods for electrodepositing platinum-group metals from molten cyanide baths. The preparation of thick, protective coating on molybdenum, inconel, graphite, stainless steel, copper, and other structural metals were studied, as well as the electroforming of platinum and iridium crucibles. Iridium, rhodium, and ruthenium can be electrodeposited under an inert atmosphere, while platinum and palladium require the presence of air. Electrolytes may be prepared by direct-current electrolysis in nacn or mixtures of nacn and kcn using anodes of the particular platinum-group metal. When the concentration of metal increases to about 0.3 Or 0.4 percent, the deposits become bright, adherent, and coherent. Current densities may be 10 to 25 ma/cm2, and plating rates are often 0.5 Mil/hr. Platinum and palladium bath deteriorate because of the oxidation of cyanide to cyanate and carbonate, and the precipitation of metal. Changes in the platinum cyanide bath are relatively slow. The protection against oxidation afforded by the platinum-group metal coatings is evaluated by testing encapsulated specimens in a thermogravimetric balance. Surface pretreatment and the use of undercoats are discussed.
IH; Report of Investigation;
NTIS Accession No.
NTIS: PB 272 913
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division