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 (14.7Ps i or 101.35KPa) to 24Psi (165.47KPa). The increase in chamber pressure resulted in (i) an increase in the crystallization of silica and carb on 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 qu antities of SiC whiskers was observed up to a temperature of 1300 degr ees C. At higher pyrolysis temperature formation of particulates throu gh coagulative recrystallization of whiskers has been observed. (C) 19 96 Elsevier Science Limited and Techna S.r.l.