Development of Si_2N_2O, Si_3N_4 and SiC Ceramic Materials Using Rice Husk

摘要

The presence of silicon in rice husk has been established by its chemical and thermal degradation. The bonding between Si and C have been studied by IR spectroscopy. The existence of IR peak at ～800 cm~(-1) shows Si-C bonding in raw rice husk, which is shifted to 790 cm~(-1) during coking and pyrolysis. ESCA study of surface showed Si, C, O and F to be present; Si in the form of SiC_x and SiO_x and C as SiC_x and CH_x. On sputtering, the SiO_x and CH_x species decrease with increase of SiC_x level. The formation of SiC from coked rice husk and Si_3N_4 and Si_2N_2O from HCl treated rice husk has been observed at 1200-1400℃ under N_2 and NH_3 atmosphere, respectively. The chemical analysis of raw rice husk and products are tabulated. The XRD analyses shows the presence of different phases in the products. A new mechanism for the development of these ceramic materials has been proposed.