SiC material produced by carbothermal reduction of a freeze gel silica-carbon artefact

A carbon-silica artefact was produced by infiltration of phenolic resin int o the macroporous texture of a silica sample followed by subsequent carboni sation. The silica material was manufactured using an Original sol-gel meth od. This work reports oft the conversion into SiC of the silica-carbon arte fact heat-treated up to 1550 degrees C under different gaseous environments . The extent of the carbothermal reduction was followed by thermogravimetri c analysis, X-ray diffraction, gas adsorption and scanning electron microsc opy. Experiment results demonstrate that a beta-SiC artefact with a shape s imilar to the starting material is obtained by heat treatment of the carbon -silica artefact above 1470 degrees C. Quantitative formation of SiC is obs erved by lowering the partial pressure of CO in the reactor. Moreover, the as-obtained SiC material exhibits a granular aspect associated with a signi ficant specific surface area, rn a more general way, the procedure describe d in this work to obtain the SiC material may be a promising route for desi gning ceramic materials with specific properties. (C) 1999 Elsevier Science Limited. All rights reserved.