GB978790A - Growth of metal fibers - Google Patents

Abstract

<PICT:0978790/C6-C7/1> <PICT:0978790/C6-C7/2> Single metal crystals or whiskers are grown on a substrate in a continuously evacuated chamber by vaporizing the metal, and maintaining the substrate at a temperature lower than the vaporizing temperature of the source metal, a part of which, in vaporized form, acts as "getter", to maintain the oxygen pressure below the oxide dissociation pressure. Details of these pressures are given. Source metals specified are Cr, Au, Ni, Cu, Fe, Co, and alloys thereof. The substrate may be the same as or different from the source metal. A fused silica sealed tube 11, Fig. 1, is surrounded at its lower end by a furnace 12, and is joined to a second tube 15, connected to a vacuum and having a lateral extension 16. A cylinder of source metal 20 has centrally suspended within it the growth substrate body 21, which extends upwards beyond the heating zone, whereby the temperature of the substrate is maintained below that of the source metal. The substrate is suspended by a tungsten wire 21, attached to a winch 27, the axis of which is rotated gy magnets 30, 33. In modifications, the source metal 20 may be in the form of a sheet wound as a spiral, by which direct heat falls on the outer surface only, and the inner coils are at successively lower temperatures. In a further form, Fig. 4, the source metal 50 is a wire mounted within the substrate body 51, and are electrically connected together, and mounted in the furnace maintained at a temperature below vaporizing temperature of the source metal. The current passing through the wire 50 vaporizes the metal, but the electrical resistance of the larger body of the substrate results in a lower temperature. Examples are given using the source metals as specified to form single crystals on the following substrates: Mo screen ; Au, Cu, and Fe as sheet metals, giving growth time, length of crystal, and vaporizing temperatures.