Biomorphic cellular silicon carbide ceramics from wood: I. Processing and microstructure

Processing of cellular ceramics with anisotropic pore structures by infiltration of liquid Silicon into carbonized wood and subsequent reaction to SiC was investigated. Natural wood of different pore size distribution and composition was carbonized at 800-1800 degrees C in inert atmosphere resulting in a one-to-one reproduction of the original wood structure. The carbon template was converted to SiC by a rapid liquid infiltration-reaction process at 1600 degrees C. Spontaneous infiltration was achieved by using the continous tracheidal cells in wood as a transportation path for liquid silicon. beta-SiC formed by solid-liquid reaction at the pore surface exhibits a crystalline texture which may be related to the initial microfibril orientation in the cell walls of wood. Depending on the initial cellular microstructure of the various kinds of wood (ebony, beech, oak, maple, pine, balsa) ceramic materials of different anisotropic pore structures in the form of pseudomorphs of the original wood were obtained. (C) 1998 Elsevier Science Limited. All rights reserved.