METHOD FOR SPINNING UNIFORM FIBRES OR FILAMENTS FROM VIRTUALLY INVISCID MELTS

摘要

1325334 Continuous casting MONSANTO CO 1 July 1970 [2 July 1969] 31868/70 Heading B3F [Also in Division C1] A fibre or filament is spun by extruding a stream 31 of molten material having a viscosity less than one poise at a Rayleigh parameter, between 1 and 25 (where V, #, D and γ are the stream velocity, density, diameter and surface tension respectively), into a gas so that a stabilizing film is formed about the stream between a point ("relaxation point") along the stream where the velocity profile 32 across the stream is flat and a point ("MPV point") where variations in the stream diameter due to wave growth first exceed 10% of the stream diameter. The melt may be Al, Cu, Fe, Pb or Sn; alloys such as Pb-Sn, steel, steel alloys or brass; intermetallic compounds; or metalloids such as As, Bo or Si. The film (e.g. formed on the stream by O 2 , propane, ammonia, BoCl 3 and water, CS 2 , CO 2 or CO in the atmosphere into which the stream is extruded) may be prevented from forming where the velocity profile 32 is insufficiently relaxed (and film disruption is likely) by protection by an inert gas before entering the film-forming atmosphere or by selection of the concentration of the filmforming component of the atmosphere, e.g. O 2 in an He/O 2 atmosphere. A gas plate as described in Specification 1,308,979 may be used for introduction of the inert gas as a flow to accelerate the melt surface and thus assist the flattening of the velocity profile 32. The relaxation distance 33 is preferably about one-half the continuous jet length 36, i.e. the length before break-up, and the orifice 19 has a low aspect ratio and small diameter. A charge of metal is melted in a crucible assembly (13), e.g. of stainless steel, by an inductor coil (20) and susceptor (12). Gas pressure then forces the melt (16) through an orifice (19) in an insert (18), e.g. of alumina, in a base member (14). Reference has been directed by the Comptroller to Specifications 1,153,577 and 1,197,972.