Fabrication and characterization of ordered macroporous PMS-derived SiC from a sacrificial template method

Three-dimensionally long range ordered macroporous SiC ceramics were prepared using a low molecular weight polymer precursor, polymethylsilane (PMS), by utilizing sacrificial colloidal silica crystalline arrays as templates which were subsequently etched off with HF (45%) after pyrolysis in an argon atmosphere. SEM, TEM, HRTEM and BET were used to specify the morphologies and BET surface areas of the porous materials. The pore sizes of about 84-658 nm and BET surface areas (pore volumes) of about 584.64 m² g^-1 (0.64 cm³ g^-1)-299.44 m² g^-1 (0.25 cm³ g^-1) of the achieved macroporous SiC ceramic were approximately proportional to the sizes 112-700 nm of the sacrificial silica sphere templates used. It was found for the first time that the unexpectedly high surfaces area and pore volumes of the achieved porous SiC ceramic were related to the microchannels on the walls that were caused by the interfacial diffusion of oxygen or silica from the silica sphere template into the walls of the SiC framework structures.