Mechanical and Thermal Properties of the Novel Ultra-light SiC Ceramic with Double-layer Hollow Interconnected Skeleton
摘要
In this paper, a novel ultra-light SiC ceramic with double-layer hollow interconnected skeleton (SSCi) was successfully synthesized by combining controllable CVI technology with an oxidation process. Pyrolytic carbon of CVI was the key technology to introduce into porosity. The pore structure, XRD, microstructure, compression properties, and thermal insulation performance of the prepared SSCi were investigated. The effect of the number of hollow layers on the SiC ceramics was also studied, which provided certain guidance for the optimization of parameters and properties of porous SiC ceramic materials. SSCi exhibited ultra-light characteristics with a density of 92 mg·cm−3. Benefiting from the double-layer hollow structure, the specific surface area of SSCi reached 906 m2·g−1. SEM results indicated that the double-layer hollow structure was successfully fabricated. SSCi consisted of two layers of SiC, and the double-layer hollow skeleton ensured the continuity of SSCi. Due to the synergistic strengthening effect of the double-layer structure, the compression strength of SSCi was enhanced. The compression strength of SSCi reached 2.55 MPa, with a specific strength of 27.72 MPa·g−1·cm3. The hierarchical energy dissipation mechanism delayed the overall failure of SSCi, and strain hardening enhanced the load-bearing capacity of the matrix. The thermal conductivity of SSCi increased most slowly with temperature. The high crystallinity of the outer SiC layer gave it strong infrared radiation reflection capability, reducing radiative heat transfer. The ultra-high specific surface area of the double-layer hollow structure also caused multiple reflections of thermal radiation, significantly hindering radiative heat transfer. SSCi exhibited potential applications in the field of high-temperature thermal insulation.