GB1272839A - Cyanidic silver electrolytes - Google Patents

Abstract

1,272,839. Electro-depositing silver. SCHERING A.G. June 17, 1969 [June 27, 1968], No.30590/69. Heading C7B. Glossy Ag is electro-deposited from a cyanidic Ag electrolyte comprising at least one S-containing compound of the formula R<SP>1</SP>-CX-NH-CS-SH or R<SP>1</SP>-CX-NR<SP>11</SP>-NH-CS-SH, and/or salt thereof with an inorganic or organic base (e.g. as Ag, Na, K, NH 4 or NH(C 2 H 5 ) 3 salt), in which R<SP>11</SP> is H or a C 1-4 alkyl (preferably methyl) group, X is S or O or imino group, and R<SP>1</SP> is an aliphatic hydrocarbon group (preferably containing C 1-5 ) or a C 1-3 alkoxy (preferably methoxy), a C 1-4 mono alkylamino (preferably methylamino) or phenylamino group or a group of the formula: in which R<SP>111</SP> is a halogen, a C 1-5 alkyl, alkoxy, alkylamino or acylamino group. When X is O or imino group, R<SP>1</SP> may be an -NH 2 group. Many examples of such glossing agents are specified such as hydrazine-N-(methyl- or phenyl-thio) carboxylic acid amide (-N-methyl)-N<SP>1</SP> -dithiocarboxylic acid, or hydrazine-N-(methyl or ethyl) guanyl-N<SP>1</SP> -dithiocarboxylic acid. The electrolyte may also contain one or more other glossing agents such as thicarbonates (e.g. Na or ethylenetrithiocarbonate), xanthatis (e.g. of K), thiocarbamates (e.g. of ammonium), organic Se compounds (e.g. a piaselenole) or inorganic Se compounds (e.g. K selenocyanate or sodium selenite) or Group V metal (e.g. Sb) compounds; wetting agents and/or colloids may be added. The C.D. may range from 0À05 to 3 amp/dm<SP>2</SP> . The electrolyte may contain 20-50 g/l Ag as AgCN, K or Na dicyanoargentate, 50-200 g/l free KCN (or NaCN) and 0-100 g/l K 2 CO 3 . 2, 5 dimercaptothiodiazole-(1, 3, 4) and thiosemicarbazide-dithiocarboxylic acid are specified as comparative glossing agents.