| abstract |
A process continuously deposits a carbonaceous film, by chemical vapor deposition, onto a moving longitudinally extending web of a plurality of matted or woven fibers, a plurality of parallel individual fibers, or a bundle of fibers, of a refractory ceramic or refractory vitreous material. The result is a coated web having a controllable resistance along its length and a substantially uniform resistance across its breadth. An organic precursor is directly applied to the web in liquid and/or solid form, the applying being at a temperature below sublimation, boiling or decomposition temperature of the precursor. The web is continuously moved through a hot chemical vapor deposition zone at a temperature of 800° C-1200° C., the zone being substantially oxygen-free, the residence time of each portion of the web within the zone being less than that which would deleteriously effect the properties of the resulting carbonaceous film coated web. The organic precursor, under the residence time and temperature conditions of the deposition zone, is selected to be substantially completely converted by sublimation, boiling and/or decomposition to one or more vaporous species. The precursor either sublimes or boils at a temperature above about 400° C. or, if it is of such a nature as to decompose rather than subliming or boiling, the decomposition temperature must be above about 300° C. The resulting web has a selectable resistance generally between about 0.1 ohm per square and 1,000 ohms per square. |