Biomorphic Cellular Silicon Carbide Ceramics from Wood: II. Mechanical Properties

Abstract

Silicon carbide ceramics with anisotropic pore microstructures pseudomorphous to wood were obtained by liquid Si infiltration of porous carbonized wood templates. Depending on the initial cellular microstructure of the various kinds of wood (ebony, beech, oak, maple, pine, balsa) ceramic materials of different density, pore structure and degree of anisotropy were obtained. Strength and elastic modulus of the pyrolyzed carbon preform and of the final silicon carbide ceramic were measured in different loading directions with respect to the initial cell orientation, e.g. axial, radial and tangential. Generally, the mechanical properties increase with fractional density. Strength and strain-to-failure in axial direction exhibit significantly higher values compared to loading in radial and tangential directions. The orientation dependence of microstructure-property relations may become important for the development of advanced anisotropic light weight structural materials.