RESUMO
Porous silicon carbide composite ceramics were prepared by partial sintering method and sacrificial silicon, with phenolic resin applied as carbon template, and silicon powder as silicon source and pore-forming agent. It showed a composite structure of SiC/SiO2/SiC sandwich shell structure and SiC/SiOX heterojunction nanofiber. Through an investigation into the effect of carbon-silicon atomic ratio on the structure and thermodynamic properties of porous SiC. It was revealed that the carbon network formed by the phenolic resin played a role in restricting the position of the silicon powder and building a regularly-arranged porous SiC structure. The prepared samples reached a porosity of 50-75% while exhibiting a low thermal conductivity ranging from 0.74 to 1.3 W/(m·K), which is attributed to the nanoscale phonon dispersion mechanism and nanofiber thermal insulation, together with high stiffness. Porous ceramics demonstrate both mechanical and thermal insulation properties, which makes them applicable as thermal protection materials for hypersonic aircraft. This is effectively in reducing the aerodynamic thermal effects of hypersonic aircraft.
