Preparation of porous SiC ceramic with a woodlike microstructure by sol-gel and carbothermal reduction processing

Highly porous silicon carbide ceramic with a woodlike microstructure has been prepared by carbothermal reduction reaction of charcoal/silica composites in static argon atmosphere, which were fabricated by infiltrating silica sol into a porous biocarbon template from Cilia amurensis wood using a vacuum/pressure infiltration process. The morphology of resulting porous SiC ceramic, as well as the conversion mechanism of wood to porous SiC ceramic, have been investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. Experimental results show that the biomorphic cellular morphology of Cilia amurensis wood charcoal tissue is remained in the porous SiC ceramic with high precision which consists of beta-SiC with traces of alpha-SiC. The strut thickness of resulting SiC ceramic becomes thinner, even partially disappears with the increase of silica amount contained in the charcoal/silica composites. The morphology of the SiC ceramic reveals that solid-solid, gas-solid and gas-gas reactions occurred during the charcoal-to-ceramic conversion. (C) 2003 Elsevier Ltd. All rights reserved.