| 摘要 |
1,051,927. Electrodepositing tin-bismuth alloys. M. & T. CHEMICALS Inc. July 7, 1965 [July 10, 1964], No.28884/65. Headings C7A and C7B. A tin-bismuth alloy having a high resistance to tin pest is cathodically deposited on a basis from an aqueous bath containing alkali metal stannate, free alkali metal hydroxide, and alkali metal bismuthate, preferably in a concentration representing 0À05 to 1 g/1 Bi and provided as sodium bismuthate. Plating is effected with C.D. of 1 to 40 amp. /dm<SP>2</SP> at 60‹C. to bath boiling point e.g. 105‹C. The preferred basic tin bath is formulated on potassium compounds and soluble or insoluble anodes may be used. The bath may be adjusted by addition of a make-up composition comprising alkali metal stannate and bismuthate in the weight proportions of 10 to 300 parts of tin to 0À05 to 1 part of bismuth, preferably 1 to 6 parts bismuth to 1000 parts tin. The alloy deposit typically contains 0À1 to 0À6% bismuth by weight. |
