Electrical and thermoelectric properties of the SiC/Si biomorphic composite at high temperatures

Abstract

The electrical resistivity ρ and the thermopower coefficient α of a SiC/Si biomorphic composite fabricated from a porous carbon matrix [prepared through pyrolysis of wood (white eucalyptus)] by infiltrating molten Si into the empty channels of the matrix were measured in the temperature ranges 100–950 and 100–750 K, respectively. Silicon reacts chemically with the carbon of the matrix to produce 3C-SiC, which, in combination with the excess Si unreacted with carbon, forms the SiC/Si biomorphic composite. The SiC/Si samples studied had a concentration of “excess” Si of ∼30 vol % and a porosity of ∼13–15 vol %. Measurements of ρ were carried out on samples cut either along (ρ∥) or across (ρ⊥) the tree growth direction, and α was measured on a sample cut along the tree growth direction.