Precursor selection and its role in the mechanical properties of porous SiC derived from wood

The compressive strength, elastic modulus, and fracture toughness of porous SiC derived from wood precursors were measured. These mechanical properties and the amount of unreacted carbon were found to be a function of porosity and pore size distribution, which are dependent on the precursor wood. The presence of residual carbon was found to have a deleterious effect on compressive strength and elastic modulus. The amount of residual carbon was quantified and found to be higher in materials derived from precursors where the pores are non-uniformly distributed and areas with a higher concentration of small pores. The pore anisotropy and density gradients in wood led to a preferred crack path along growth rings in directions parallel to the wood growth direction. These findings can be used to select the proper precursor wood to obtain the desired properties in the final porous SiC.