| 摘要 |
1,224,507. Electro-deposition of bright hard pink gold alloys. SEL-REX CORP. March 11, 1968, No.11782/68. Headings C7A and C7B. Bright hard pink gold-copper-antimony alloys are electro-deposited from an aqueous bath comprising per litre 1 to 8 gms gold (as alkali gold cyanide), 2 to 10 gms copper (as a copper complex), 0.5 to 10 gms antimony (added as a salt), 5 to 60 gms chelating agent in addition to any complexed with the copper and a weak acid and/or a salt thereof to buffer the solution to a pH of 4.5 to 6, using a bath temperature of 40 to 60‹ C. and a current density of 0.5 to 2 amps/dm<SP>2</SP>. Typically the gold is provided as potassium aurocyanide, the copper is added as a salt of the chelating agent which is disodium EDTA, or other polyaminopolyacetic acid or its salt the antimony is provided as crystalline antimony tartrate, and the buffer is an alkali metal acid orthophosphate, tetrasodium pyrophosphate or other phosphoric acids or their acid salts or mixtures thereof, e.g. the sodium or potassium acid salts of the commercial mixture known as polyphosphoric acid, acetic acids and/or its sodium or potassium salts, or soluble mono-alkali metal salts of citric or tartaric. The bath may include up to 200mg/1 of lead added as lead acetate or lead EDTA to avoid hazing of the bath and to improve levelling and brightness of the deposit. Deposit thickness of 25Á or more may be obtained. The alloys comprise by weight 75 to 85% gold, 14 to 24% copper and 0.5 to 1À5% anti-mony, with possibly traces of lead. |
