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 (kτ ≈ 10.3 W·m-1·K-1 at room temperature), and high anisotropic thermal conductivity (kτ/k||, â'¼1.6). The orientation dependence of the microstructure-property relations may offer a promising perspective for the fabrication of multifunctional ceramics and composites.