Thermal plasma synthesis of SiC from rice hull (husk)
Recently the synthesis of ultrafine powders has drawn considerable attention because these powders can have physical and chemical properties superior to those of bulk specimens. In particular, emphasis is on the preparation of ultrafine ceramic powders for their applications in the development of sintered products having higher density and lower sintering temperature. One such industrially important ceramic material is SiC. In many cases ultrafine SiC has been prepared by thermal plasma processes [1]. However, these processes require one or more reactive/corrosive gases. This letter describes a new method to overcome such problems. For this purpose thermally pretreated rice hull was used as the solid precursor. Rice hull, an agricultural waste product, was first used by Cutler [2] as a starting material for the production of silicon carbide. Since the rice hull route promises to be most economical, much attention has recently been paid to it [3-6]. Rice hull consists of silica in hydrated amorphous form, and cellulose which yields carbon when thermally decomposed. The relative abundance of silica with very high surface area in close proximity to active carbon in rice hull makes it amenable for SiC formation during the pyrolysis process. The possible reaction was given by Lee and Cutler [7] as
Synthesis of SiC from rice husk in a plasma reactor
A new route for production of SiC from rice husk is reported by employing thermal plasma technique. The formation of β-SiC is observed in a short time of 5 min. The samples are characterized by XRD and SEM.
The growth of silicon carbide needles by the vapor-liquid-solid method
Abstract Single crystal needles of alpha (2H-wurtzite) silicon carbide have been grown under controlled conditions by the hydrogen reduction of purified methyltrichlorosilane onto silicon carbide coated graphite susceptors. Previous work of Ryan et al. has been extended and more precise specifications of growth conditions of the 2H modifications have been determined. The 2H crystals were grown several millimeters in length by one millimeter diameter. They were optically clear and had sharply defined face. Their growth morphology was compatible with the VLS mechanism. The crystals were characterized by optical microscopy, electron microscopy and electron microprobe techniques. A detailed X-ray investigation of the anomalous behavior of these 2H crystals under thermal annealing is presented in a companion paper (Krishna and Marshall, this meeting).