Fabrication of Porous Cellular SiC Ceramics from Wood by Embedding in Si/SiO₂ Powder Mixture

Abstract

Wood has strongly anisotropic cellular structure with 50-80 vol% porosity. It can be converted into porous ceramics (e.g., SiC, SiC/Si, TiC, C/C, and TiO2) replicating the wood structure by various processes. Previously porous cellular SiC ceramic was prepared by reaction of wood charcoal with gaseous SiO generated remotely from an equimolar mixture of Si and SiO2. In the present work, poplar charcoal was simply embedded in the powder mixture of Si and SiO2 and heated at 1600°C for 1 h in Ar to produce porous SiC. Samples were also prepared by infiltration of Si melt (1500-1600°C, 2 h) and vapor (1700°C, 2 h) into the charcoal for comparison. Samples prepared by Si melt infiltration showed 15-52% conversion to SiC. Samples prepared by Si vapor infiltration showed severe damage such that the conversion degree could not be measured. In contrast, samples prepared by the embedding process showed full conversion to SiC (mostly β form) with good retention of the cellular structure of the original wood. The embedding process is a simple and efficient way to produce porous cellular SiC from wood.