Biomorphic cellular silicon carbide ceramics from wood: II. Mechanical properties

Silicon carbide ceramics with anisotropic pore microstructures pseudomorpho us to wood were obtained by liquid Si infiltration of porous carbonized woo d templates. Depending on the initial cellular microstructure of the variou s kinds of wood (ebony, beech, oak, maple, pine, balsa) ceramic materials o f different density, pore structure and degree of anisotropy were obtained. Strength and elastic modulus of the pyrolyzed carbon preform and of the fi nal silicon carbide ceramic were measured in different loading directions w ith respect to the initial cell orientation, e.g. axial, radial and tangent ial. Generally, the mechanical properties increase with fractional density: Strength and strain-to-failure in axial direction exhibit significantly hi gher values compared to loading in radial and tangential directions. The or ientation dependence of microstructure-property relations may become import ant for the development of advanced anisotropic Eight weight structural mat erials. (C) 1998 Elsevier Science Limited. All rights reserved.