GB1279252A - Improvements in or relating to apparatus for coating fibres - Google Patents

Abstract

1279252 Glass fibres; coating fibres with glass UNITED KINGDOM ATOMIC ENERGY AUTHORITY 29 Oct 1969 [1 Nov 1968] 52023/68 Heading C1M [Also in Divisions C3 and D1] Fibres in a tow 11 are passed through a coating slurry 27 of a powdered glass in a binder and solvent, in the form of a flat ribbon, the two being transported by a series of rollers after unwinding from a container 12, air being directed from spaced fish-tail nozzles 25 and 26 in opposed manner between the tow and respective rollers 16 and 21, the subsequent rollers having flanges to define the width of the ribbon, and light mangling being effected by rollers 23 and 24. As shown, the tow passes between a partially immersed roller 22 in a tapered coating vessel 28, coating material being re-cycled from an outlet 44 to a nozzle 31 similar in shape and position to nozzles 25 and 26. In another embodiment (Fig. 2), a modified vessel dispensing with nozzle 31 and containing a plurality of immersed rollers is employed, and the coating material is stirred without recirculation by passage of air upwards through a glass filter plate at the base of the vessel. The fibres may be of carbon, glass or metal or of an organic material but particularly carbon. The slurry may be of 5 to 15% by volume nucleated or boro-silicate glass in 5 to 15% polyvinylalcohol binder and 90 to 70% methyl-ethyl ketone solvent. The coated fibres are wound on to a square cross-section take up drum (Fig. 3). Rectangular composite sheets (65, Fig. 3) of the coated tow may be cut from the take up drum and pressed in a mould under high temperature and pressure; for a boro-silicate matrix, the composite is pressed in a stainless steel mould coated with colloidal graphite at 5000 p.s.i. at 900‹ C.; for a nucleated glass matrix, the composite is pressed in a graphite mould coated with colloidal graphite at 1500 p.s.i. at 1300 ‹C. The composite may be coated during or after pressing with glass, a resin or silicon which is subsequently nitrided; the coating may be applied as a slurry of the powdered coating material in a binder on to a carrier which is dried and partially cured before being placed on the composite. The mould may be lined with molybdenum strip.