GB838350A - Improvements relating to the electrodeposition of platinum - Google Patents

Abstract

838,350. Electrodeposition of platinum. MOND NICKEL CO. Ltd. Nov. 20, 1956 [Dec. 2, 1955], No. 35478/56. Class 41. Crack-free platinum is electrodeposited from an aqueous acidic chloride-chloroplatinate bath containing per litre 180 to 300 gms. hydrogen chloride and 10 to 50 gms. platinum at a temperature of 45‹ to 90‹ C. by regulating the conditions of electrolysis to maintain the rate of deposition on the cathode such that when plotted against the hydrogen chloride concentration of the bath it is represented by a point within the area FGHEF in the accompanying drawing. Further by controlling the conditions so that the representative point is within the area ABCDEA, deposits are obtained which can be reduced in thickness by 20% by cold working without cracking or loss of adhesion. The Specification indicates that the ratio chloroplatinic: chloroplatinous ions should be greater than 20: 1, the required control is achieved on an empirical basis and that metals which codeposit with platinum, ions which form insoluble chloroplatinates or insoluble acids, e.g. tungstic and molybdic acids, and strong oxidizing and reducing agents, should be excluded from the baths. Anodes of platinum or rhodium may be used, and deposits may be made on metals such as iron, copper, nickel, zinc and silver which are attacked by the acid bath by first applying a strike of gold, platinum, palladium, or rhodium from a high pH, low metal bath.