Porous Design of SiCNWs/SiC Nanocomposites with High Strength and Low Thermal Conductivity

Abstract

Porous SiC composites with lightweight, high strength and low thermal conductivity design can be obtained by constructing porous silicon carbide nanowires (SiCNWs) network and controlling chemical vapor infiltration (CVI) process. The SiCNWs network with an optimized volume fraction (13.6%) and uniform structure is prepared by mixing SiCNWs and polyvinyl alcohol (PVA) firstly. SiCNWs reinforced porous SiC composite (SiCNWs/SiC) with a small uniform pore can be obtained by controlling the chemical deposition kinetics. The morphology of the grown SiC matrix, from the spherical particles to the hexagonal pyramid particles, can be influenced by the deposition parameters like temperature and reactive gas concentration. The strength of the lightweight SiCNWs/SiC composites reach 47.8 MPa with a porosity of 64% and thermal conductivity of 1.2 W/(m∙K), which shows the toughening effect and insulation design with low thermal conductivity.