Intrinsic microstructures of silica-bonded porous nano-SiC ceramics

Silica-bonded porous SiC ceramics were fabricated using nano-beta-SiC powder-carbon black template compacts by sintering in air at 600 degrees C-1200 degrees C. The intrinsic microstructures of the porous ceramics were characterized by high-resolution transmission electron microscopy, which led to the following observations: (a) a core (SiC)-shell (SiO2) structure was formed, owing to the partial oxidation of nano-SiC particles during sintering; (b) a low-temperature (800 degrees C) beta-to-alpha polytypic phase transformation was observed, owing to the oxidation-induced residual thermal stresses; and (c) non-graphitic carbons were precipitated inside the SiC core, owing to the segregation of C atoms emitted at the strained SiC-SiO2 interface.

Automated summary

Porous SiC ceramics with a core-shell structure were fabricated by sintering nano-SiC powder-carbon black compacts in air. During sintering, oxidation of SiC particles led to the formation of a SiO2 shell, while low-temperature phase transformation and precipitation of non-graphitic carbons were also observed.