Patent GB-1153577-A (GB)
Title: Fibers, Filaments and Films and their manufacture
IPC: B22D11/00
Filed: 1966-03-29
Abstract: 1,153,577. Continuous casting; casting composite wires or ribbons. MONSANTO CO. 29 March, 1966 [30 March, 1965; 1 Dec., 1965], No. 13717/66. Heading B3F. [Also in Divisions C1, C2 and C7] Fibres, filaments and films, including rods, wires or ribbons, are formed by generating a free stream of a low viscosity melt (e.g. by extruding through a die, i.e. spinning, or throwing off from a high speed centrifugal cone) and simultaneously forming a film on the stream, to prevent the stream breaking up before solidification. Viscosities of less than 1000 poises are mentioned. The stabilizing film may be formed by:- (1) reaction of the surface of the stream with the atmosphere chosen to surround it, (2) by decomposition, e.g. by pyrolysis, of either or both the stream surface and the atmosphere, or (3) deposition of a coating on the stream, by evaporation or sputtering of coating material or of material forming with the atmosphere a coating, say an oxide, for the stream. Melts of different materials may flow together near the extrusion orifice to form composite filamentary structures. The melt may be non- metal (see Divisions C1 and C2). Metals specified are Al (and some alloys thereof), Be, Cu (possibly containing some Al), Au, Pb, Mn, Ni containing some Th or Cr &c., Sn, U, V, Zn, Wood's metal and alloys of steel with Al including a stainless steel containing Al. In the spinning apparatus shown, argon or nitrogen is introduced at 26 to extrude the material (melted in a crucible 14 by a resistance-heater or induction coil 32) through an orifice 16, which may be in a sapphire seated in the crucible bottom, or through a number of orifices, to pass by way of a quartz or glass support-cylinder 34, into a cylindrical chamber 12 containing the required atmosphere and having an observation port 46. The orifice 16 is of the order of 35-450 microns diameter. The resulting fibres, when of metal, are said to have an internal microstructure with dendrite spacing less than 25 microns. There are examples of atmospheres, for receiving extruded metal, of oxygen (frequently mixed with argon, helium or nitrogen and possibly at less than atmospheric pressure) so that a film of oxide is said to be formed, sometimes of a minor constituent (such as Al or Th) of an alloy. Atmospheres of ammonia with argon or nitrogen are said to produce nitride films in the case of Zn and some of the Al-containing alloys. In the case of extruded U, an atmosphere of nitrogen alone results in a nitride film. Al or an alloy thereof extruded into an atmosphere of hydrogen sulphide mixed with nitrogen and possibly hydrogen is said to be stabilized by an aluminium sulphide film. Carbon disulphide is said to produce a carbon film on Cu and a sulphide or carbon film on Mn, while carbon is deposited on Au from a propane atmosphere. To reduce dissolving of the film in the melt, the latter may be saturated with the film (or other) material before film-formation. There may be included in the melt a small amount of a constituent which produces a film having a diffusion rate or solubility in the melt, lower, or a melting point higher, than that of the film which would be produced by the main constituents of the melt. Steel for example may contain a little Al to produce an aluminium oxide film.