Process for the preparation of silicon carbide whiskers

Abstract

The invention relates to a process for the preparation of silicon carbide whiskers by the reaction, in a non-oxidizing atmosphere, at a temperature of at least 1300.degree. C., of a charge composed of a mixture of carbon black and a source of silicon oxide, in which process the carbon black has an oxidability rate (measured by heating in air for 30 minutes at 600.degree. C.) of at least 85%, the silicon oxide source has a grain size of less than 100 .mu.m and the rate of rise in temperature between 1300.degree. and 1600.degree. C. is less than 30.degree. C.min.sup.-1 per minute if a static atmosphere prevails and at most 25.degree. C.min.sup.-1 if gas percolated. A stage of from 5 min to 5 h at 1600.degree. C. is optionally carried out. The carbon is preferably introduced into the reaction mixture in an over-stoichiometric quantity relative to the silica. The excess carbon is removed at the end of the reaction by oxidation in air at about 600.degree. C.

Dependencies are inferred from the claim text.