GB1142568A - Passage structure - Google Patents

Abstract

1,142,568. Making wire. BRUNSWICK CORP. 6 July, 1966 [12 July, 1965], No. 30279/66. Heading B3A. [Also in Divisions C7 and H1] A body, e.g. a metal body suitable for use as an electrolytic capacitor anode has its surface area increased by the provision of substantially rectilinear through passages each having a maximum cross-section dimension of under 10 mils and a length to maximum cross-section dimension ratio of over 10. The metal may be tantalum, aluminium, niobium, titanium, hafnium, vanadium, zirconium, stainless steel, iron, nickel or tungsten, uses other than in capacitors being envisaged. To form the body, a bundle of hexagonal cross-sectional wires 14 each sheathed by metal tubes 15 is supported within a can 17 by spacers 15a (Fig. 3a) and the assembly is constricted to reduce its cross-sectional diameter by rolling, extruding and/or drawing and form a body comprising the now elongated wires 14 embedded in a matrix of the metal which formed tubes 15. The material of the wires 14 is now removed, suitably after cutting the constricted body into short lengths, using, e.g. an acid which does not attack the matrix metal. The body thus formed has ninety-one through passages, but bodies having a larger number of passages may be formed by bundling lengths of the originally constricted body as shown in Fig. 9 and carrying out the constricting processes again. Preferably the material of can 17 is first removed. Preferably the passages occupy more than 9% of the cross-sectional area, are spaced apart less than 10 microns and have a variation of cross-section along their length and from passage to passage of less than 10%. The cross-sectional dimension of the passages may be less than 2 microns. For use in electrolytic capacitors (Fig. 1, not shown) the body has an anodic oxide film formed by conventional methods, and the electrolyte may be liquid or solid, e.g. manganese dioxide formed by pyrolysis in situ of manganese nitrate.