Heat-resistant constant black fibers and - substances which are derived from regenerated, certain cellulose containing heavy metals derived

摘要

1282888 Heat-resistant carbonaceous fibrous material MINNESOTA MINING & MFG CO 27 June 1969 [28 June 1968] 32719/69 Heading C1A [Also in Division G6] A carbonaceous fibrous material containing by weight ¢ to 6% of nitrogen, 40-95% of carbon and 1 to 50% of a heavy metal of Groups IVb, Vb or VIb of the Periodic Table which is chemically bound to the carbonized fibre in a non- carbide form but which is capable of reacting with carbon to form a refractory stable carbide, is prepared by impregnating a regenerated cellulose fibre with a solution of a salt or salts of one or more heavy metals, and a water-soluble salt of a strong acid and a nitrogenous base, drying and heating the impregnated fibre in a pyrolysis process to a temperature of at least 700‹ C. but below that at which the heavy metal carbide would form. The pyrolysis may be carried out in either a one-stage process using a non-oxidizing environment, or a two-stage process wherein the fibre is dried and heated for at least one minute at a temperature of at least 200‹ C. in the presence of air so as to cause the fibre to pass through the pyrolytic stage and produce an electrically non-conducting fibre having a carbon content of 50 to 65% by weight and a nitrogen content of at least 1% by weight, each being exclusive of heavy metal, and then, carbonizing this fibre in a non-oxidizing environment. Suitable heavy metals are fissionable actinides, W, U, Ta, Th, Zr and Mo.