GLASS-FIBERS WITH FINE CONDUCTING CORES

New methods are described for producing glass fibres containing single or multiple metallic filaments along their axes. The new processes are based upon that first described in 1924 by Taylor. His method consisted in melting a small amount of metal within a glass capillary and of then drawing a fibre from the softened glass. Fibres containing single, submicrometre diameter metal or semiconductor filaments are prepared by inserting a composite fibre prepared by Taylor's method in a glass capillary and drawing from this assembly a new fibre in which the diameter of the axial filament is reduced in proportion to the ratio of the diameters of the capillary and the new fibre. This method has produced filaments substantially less than 1 mum diameter. The second new process consists in drawing a fibre from a tube filled with a mixture of metal and glass powders. This method can produce fibres containing hundreds of filaments within any given cross-section. The filaments are of limited length, however, and they have a spectrum of diameters which depend on the powder particle-size distribution and the processing conditions. They typically range from a few micrometres in diameter down to a fraction of a micrometre.