From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Procedure for the preparation and application of an indium plating solution for bearings.
| Identifier | ExFiles\Box 115\2\ scan0538 | |
| Date | 14th December 1939 guessed | |
| - 3 - After lead plating the lead anode is removed and the bearing rinsed in cold water, soaked in a 5% solution of sodium cyanide for at least 5 minutes and rinsed again in cold water. The lead plating is impregnated with sodium to prevent damage by scid oil. The process is as follows:- The solution, Indium: 33.0 grams/litre. Dextrose: (USP) 15.1 grams/litre. Sodium cyanide: 119.3 grams/litre. The indium is cut into small pieces and dissolved in a minimum quantity of hydrochloric acid, heated. The Na{Mr Nadin}/CN{Mr Chamberain} is dissolved in distilled water (500 ml. for 15.1 grams of Na{Mr Nadin}/CN.{Mr Chamberain}) The Dextrose is added to the Na{Mr Nadin}/CN{Mr Chamberain} solution, slowly, with constant stirring. (Fumes are dangerous.) Concentrated solution must stand 48 hours or longer. Filter concentrated solution and make up required volume with water. The plating bath is operated at room temperature. Current density is 15 amperes per sq. ft. The time of plating is determined by the rate of plating, which varies with the age of the bath. The rate of plating is tested by plating a copper strip 3" long by 1" wide, for 3 minutes at 1 ampere and comparing the weight before and after plating. The time for plating the bearing then is determined by the formula time (in minutes): 58.8 --------------------------------------- Mg. of indium plated per ampere minute. The indium content of the solution is maintained at 29.33 grams. per litre. Free Na{Mr Nadin}/CN{Mr Chamberain} content is maintained at 60 - 90 grms per litre. Tanks for indium solution are glass, earthenware or welded steel. | ||