Film of pyrolytic graphite having bi-directional reinforcing properties

Abstract

A thin film of substantially defect-free pyrolytic graphite, useful as a bi-directional reinforcing material, is formed by vapor deposition on an inert liquid substrate surface and separated therefrom. The substrate temperature is substantially below the melting point of the refractory material and the substrate surface is smooth and free of stress to enable formation of a substantially defect-free film. Thin films of other refractory materials can be made similarly by first forming a pyrolytic graphite film on the substrate, and then vapor depositing a film of refractory material on the pyrolytic graphite surface. The pyrolytic graphite and refractory material films are then separated from the substrate surface and then separated from each other. Various refractory film materials can be made including pyrolytic grahite; boron; silicon; and refractory carbides, borides and nitrides. For making pyrolytic graphite films, it is preferable to use tin as the ubstrate, at a temperature of about 1600-1800.degree. C., at atmospheric pressure, a source gas consisting of methane and argon, helium, or hydrogen, and a film residence time on the substrate surface of about 0.16-2 minutes.

Dependencies are inferred from the claim text.