Formation of SiC whiskers from raw rice husks in argon atmosphere

Raw rice husks without pre-coking were directly pyrolysed at different temperatures between 1050 and 1600 degrees C in argon atmosphere. The furnace chamber pressure was varied from atmospheric pressure (14.7Psi or 101.35KPa) to 24Psi (165.47KPa). The increase in chamber pressure resulted in (i) an increase in the crystallization of silica and carbon in rice husks, (ii) an increase in the temperature of SiC formation from 1100 to 1150 degrees C, and (iii) a decrease in the formation of SiC whiskers, and the total SiC content. Formation of considerable quantities of SiC whiskers was observed up to a temperature of 1300 degrees C. At higher pyrolysis temperature formation of particulates through coagulative recrystallization of whiskers has been observed. (C) 1996 Elsevier Science Limited and Techna S.r.l.