| abstract |
This invention concerns an essentially cylindrical discrete carbon fibril characterized by a substantially constant diameter between about 3.5 and about 70 nanometers, e.g. between about 7 and 25 nanometers, length greater than about 102 times the diameter, an outer region of multiple essentially continuous layers of ordered carbon atoms and a distinct inner core region, each of the layers and core disposed substantially concentrically about the cylindrical axis of the fibril. Preferably the entire fibril is substantially free of thermal carbon overcoat. The invention further concerns a plurality of such fibrils. The fibril or plurality of fibrils of this invention may be produced by contacting for an appropriate period of time and at suitable pressure a suitable metal-containing particle with a suitable gaseous, carbon-containing compound, at a temperature between about 850 DEG C. and 1200 DEG C., the ratio on a dry weight basis of carbon-containing compound to metal containing particle being at least about 100:1. The fibrils are useful in composites having a matrix of e.g., an organic polymer, an inorganic polymer or a metal. In one embodiment the fibrils are incorporated into structural materials in a method of reinforcement. In other embodiments the fibrils may be used to enhance the electrical or thermal conductivity of a material, to increase the surface area of an electrode or capacitor plate, to provide a support for a catalyst, or to shield an object from electromagnetic radiation. |