GB709537A - Method of and device for etching aluminium foils - Google Patents

Abstract

709,537. Etching. ALUMINIUM-WALZWERKE SINGEN GES. Feb. 13, 1952 [Feb. 14, 1951], No. 3871/52. Class 100 (2) In a method of etching aluminium foils, for the purpose of increasing their active surface, the foils are roughened in a first step in an etching bath and are then further roughened in one or more other etching baths in succession ; the aggressiveness of the etching solution being reduced from bath to bath. The aggressiveness of the solution may be reduced by lowering the temperature or by lowering the concentration of the solution. As shown, a pickled aluminium foil is drawn through three acid troughs 1, 2, 3 over glass or china rollers 5. Contact chronometers 6 may control automatically the heating and cooling of the troughs by means of relays. Steam nozzles 7 effect the heating, whilst water sprays 8 effect the cooling. The etching solution may be moved in the opposite direction to that of the foil. In one example the foil is roughened in the first stage for 110 seconds in a warm bath at 30‹ C. of 400 c.c. of 32 per cent HCl, 100 c.c. of concentrated HNO 3 , 100 gms. FeCl 3 and a litre of water containing 15 grams of aluminium. Second stage etching is effected for 120 seconds at a temperature of 25‹ C. by a solution of 10 per cent HCl containing 10 gms. of aluminium per litre. The etching may be promoted in one or more stages by the use of direct or alternating current. The invention is applicable to batch etching as well as continuous etching.