Biomorphic Cellular Silicon Carbide Nanocrystal-Based Ceramics Derived from Wood for Use as Thermally Stable and Lightweight Structural Materials

Abstract

Ultrastrong, biomorphic cellular silicon carbide (bio-SiC) ceramics were generated by the carbothermal reduction of gaseous SiO with a pyrolytic carbon template. The anisotropic wood tissue microstructure is replicated in the bio-SiC materials, in which almost fully dense cell walls are assembled by directional columnar SiC nanocrystalline structures that are 100–200 nm in diameter and 100–500 nm in length. The resulting bio-SiC ceramics exhibited high porosity (76%∼86%), superior flexural strength to other materials (σ|| ≈ 38.3 MPa), high thermal dissipation characteristics (k⊥ ≈ 10.3 W·m–1·K–1 at room temperature), and high anisotropic thermal conductivity (k⊥/k||, ∼1.6). The orientation dependence of the microstructure–property relations may offer a promising perspective for the fabrication of multifunctional ceramics and composites.