Flash sintering (FS) is a novel technique for rapidly densifying silicon carbide (SiC) ceramics. This work achieved a rapid sintering of SiC ceramics by the utilization of ultra-high temperature flash sintering within 60 s. Pyrolysis carbon (PyC) “bridges” were constructed between SiC particles through the carbonisation of phenolic resin, providing a large number of current channels. The incubation time of the flash sintering process was significantly reduced, and the sintering difference between the centre and the edge regions of the ceramics was minimized, with an average particle size of the centre region and edge region being 12.31 and 9.02 μm, respectively. The results showed that the porosity of the SiC ceramics after the flash sintering was reduced to 14.79% with PyC “bridges” introduced, and the Vickers hardness reached 19.62 GPa. PyC “bridges” gradually evolved from amorphous eddy current carbon to oriented graphite carbon, indicating that the ultra-high temperature environment in which the sample was located during the flash sintering was successfully constructed. Ultra-high temperature flash sintering of SiC is expected to be applied to the local repair of matrix damage in SiC ceramic matrix composites.

Ceramic fibrous aerogels are highly desirable for thermal management materials due to their high porosity, excellent elasticity, thermal conductivity, and good thermal resistance. However, the fabrication of nanofibrous aerogel with super-elasticity and good shape retention at the same time has remained challenging. To meet the requirements, a novel anisotropy nanofibrous-granular aerogel with a quasi-layered multi-arch-like and hierarchical-cellular structure is designed and prepared by vacuum-filtration-assisted freeze-drying and sintering. The quasi-layered multi-arch and flexible nanofibers endowed the aerogels with excellent mechanical robustness (ultimate stress up to 60 kPa with strain 60%) and super-elasticity with recoverable compression strain up to 60%. The introduced SiO₂ aerogel nanoparticles and nanofibers are assembled into an arch-like structure and become the connection point of adjacent nanofibers, which endows low thermal conductivity (0.024 mW/(m·K)) of composite aerogel. This novel strategy provides a fresh perspective for the preparation of nanofibrous aerogel with robust mechanical in thermal insulation and other fields.

Porous three-dimensional SiC/melamine-derived carbon foam (3D-SiC/MDCF) composite with an original open pore structure was fabricated by the heat treatment of the commercial melamine foam (MF), carbonization of the stable MF, and chemical vapor deposition of the ultra-thin SiC coating. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to detect the microstructure and morphology of the as-prepared composites. The results indicated that the 3D-SiC/MDCF composites with the coating structure were prepared successfully. The obtained minimum reflection loss was -29.50 dB when the frequency and absorption thickness were 11.36 GHz and 1.75 mm, respectively. Further, a novel strategy was put forward to state that the best microwave absorption property with a thin thickness of 1.65 mm was gained, where the minimum reflection loss was -24.51 dB and the frequency bandwidth was 3.08 GHz. The excellent electromagnetic wave absorption ability resulted from the specific cladding structure, which could change the raw dielectric property to acquire excellent impedance matching. This present work had a certain extend reference meaning for the potential applications of the lightweight wave absorption materials with target functionalities.