JPH0380759B

PURPOSE:A composition containing elementary carbon and silicon oxide is heat- treated in the presence of a breathable structure to enable high-yield production of silicon whiskers having high unifomity in length, thickness and shape. CONSTITUTION:A breathable structure is prepared by piling up a plurality of pieces made of a substance which resists deformation even at 1,300-1,800 deg.C to hold its pores, e.g., carbonized cylinder of about 15mm. outer diamter, about 20mm. length and about 0.1mm. thickness from kraft peper. Then, a decomposable silicon compound such as SiCl4 and a carbon compound such as light oil is introduced into a hot gas including steam and the formed aerosol of silicon oxide and elementary carbon is subjected to solid-gas separation to form a carbon-containing composition of less then 0.2g/cc bulk density. Then, the composition is heated at 1,300-1,800 deg.C in the state the pores of the above- cited breathable structure are filled with the carbon composition.