Porous SiC ceramics fabricated by reactive infiltration of gaseous silicon into charcoal

Basswood has been converted to a porous biocarbon template by carbonizing under vacuum at 1200degreesC. Subsequent reactive infiltration of gaseous silicon at 1500-1700degreesC for 0.5-8 h in inert atmosphere resulted in the formation of a porous, cellular beta-SiC ceramic. X-ray diffraction (XRD) studies show the resulting SiC, obtained at 1600degreesC for 6 h in static argon atmosphere, is beta-SiC. Scanning electron microscopy (SEM) reveals the resulting SiC ceramic reproduces the biomorphic cellular morphology of basswood tissue with high precision. Gaseous Si diffuses into charcoal through its continuous tracheidal cell channels, and reacts with carbon in the cell wall to form SiC. Growth of SiC layer is dependent of the diffusion of Si vapor through the primary porous SiC layer and further gas-solid reaction of Si(g) and C(s) at C/SiC interface. The densification of SiC strut material may occur at moderate temperatures and holding time. (C) 2003 Elsevier Ltd and Techna Group S.r.l. All rights reserved.