GB812930A - Improvements in and relating to a method and apparatus for the deposition of metallic coats on rovings of glass fiber - Google Patents

Abstract

812,930. Coating with metals. COMMONWEALTH ENGINEERING CO. OF OHIO. Dec 30, 1955, No. 37365/55. Class 82(2) Rovings of glass fibres are heated to the decomposition temperature of a heat-decomposable, gaseous metal-bearing compound and vigorously vibrated in an atmosphere of such compound to attain a uniform deposition of the metal. Drawing speeds of 1-300 ft./min. and a vibration frequency of 520-1750 cycles per minute may be used. The plating gas may be nickel carbonyl, copper acetyl acetonate, molybdenum carbonyl, chromium hexacarbonyl or a metal hydride. Sub-atmospheric or atmospheric plating pressures may be used. In the form shown, carbon dioxide gas from cylinder 1 passes via a carburetter 7 containing nickel carbonyl to a T-junction 13 of a chamber 14 with an enlarged portion 17 containing an eccentric shaft 19 and an aperture 29. A glass plating chamber 15 has an extension 33 with a cooling means 35 which isolates a heater 37 from the chamber 15. Connected to extension 33 is a trap 43 maintained by dry ice 45 at about -20‹C. to condense nickel carbonyl. The trap 43 is connected to a pump 49 for the expulsion of gases to a burner which may be a resistance heater over which the uncondensed material flows, and to a pump 57 for the return of recovered carbonyl to the carburetter 7. It it is desired to replace the nickel carbonyl by a compound which is solid at room temperature the carburettor 7 may be surrounded by an oil bath, stirred and heated, with a themostatic control (Fig. 2, not shown). To ensure no leakage of carbonyl gas from chamber 14, carbon dioxide is passed into it from cylinder 27. The eccentric 19 causes the roving to vibrate and open (Fig. 4) to expose each filament to the plating gas. The plated roving then compacts (Fig. 5). It may be desirable to keep the roving temperature low, such that the drop in temperature whilst traversing chamber 15, is sufficient to prevent plating at the left end of the chamber. The opening 63 of extension 33 may initially have a diameter only slightly greater than that of the roving 38.