Rv. Krishnarao et al., CONVERSION OF RAW RICE HUSKS TO SIC BY PYROLYSIS IN NITROGEN ATMOSPHERE, Journal of the European Ceramic Society, 18(2), 1998, pp. 147-152
Raw rice husks without precoking were directly pyrolysed in a graphite
resistance heating furnace at 1100-1400 degrees C in nitrogen atmosph
ere. The furnace chamber pressure was varied from atmospheric pressure
(14.7 Psi or 101.3 KPa) to 24 Psi (165 KPa). Considerable quantities
of SiC whiskers were formed at 1200-1400 degrees C. Small quantities o
f Si2N2O were also formed at 1100 and 1200 degrees C. No Si3N4 was for
med. The increase in chamber pressure has resulted in (i) an increase
in the crystallization of silica and carbon in rice husks, (ii) decrea
se in the formation of SiC whiskers. Pyrolysis in nitrogen atmosphere
resulted in the formation of good quality (needle type) SiC whiskers.
(C) 1997 Elsevier Science Limited.