Mechanical properties and microstructure of biomorphic silicon carbide ceramics fabricated from wood precursors

Silicon carbide-based, environment friendly, biomorphic ceramics have been fabricated by the pyrolysis and infiltration of natural wood (maple and mahogany) precursors. This technology provides an eco-friendly route to advanced ceramic materials. These biomorphic silicon carbide ceramics have tailorable properties and behave like silicon carbide based materials manufactured by conventional approaches. The elastic moduli and fracture toughness of biomorphic ceramics strongly depend on the properties of starting wood preforms and the degree of molten silicon infiltration. Mechanical properties of silicon carbide ceramics fabricated from maple wood precursors indicate flexural strengths of 344±58 MPa at room temperature and 230±36 MPa at 1350 °C. Room temperature fracture toughness of the maple based material is 2.6±0.2 MPa√m while the mahogany precursor derived ceramics show a fracture toughness of 2.0±0.2 MPa√m. The fracture toughness and the strength increase as the density of final material increases. Fractographic characterization indicates the failure origins to be pores and chipped pockets of silicon.