Preparation of ordered mesoporous silicon carbide monoliths via preceramic polymer nanocasting

Ordered mesoporous silicon carbide (SiC) monoliths have been synthesized using polycarbosilane as starting preceramic polymer and mesoporous silica SBA-15 as start template. SiC-carbon composite monoliths were generated via nanocasting, pressing, and subsequent pyrolysis under nitrogen at 1000 °C and 1200 °C, respectively. Finally, the carbon template was removed through thermal treatment in an ammonia atmosphere to obtain SiC monoliths with ordered mesoporous structures. Investigated by small-angle X-ray diffraction (SA-XRD), powder wide-angle X-ray diffraction (WA-XRD), transmission electron microscopy (TEM), field emission scanning electron microscope (FE-SEM), the nitrogen adsorption–desorption isotherm measurements and thermogravimetric analysis (TGA), the SiC monoliths display crack-free, ordered 2-dimentional hexagonal p6mm symmetry, high specific surface areas and oxidation stability. The porous ceramic monoliths possess compression strength of about 33.5 MPa, which is adequate for their use in several engineering applications.

Crack-free, high mechanical strength, ordered mesoporous silicon carbide (SiC) monoliths have been synthesized using polycarbosilane as starting preceramic polymer and mesoporous CMK-3 carbon as hard template, via nanocasting, pressing, and subsequent pyrolysis under different atmospheres.Figure optionsDownload as PowerPoint slideHighlights
► Ordered mesoporous SiC monoliths were prepared by preceramic polymer nanocasting.
► Polymer-template composite monoliths were obtained by pressing without any binder.
► As-prepared monoliths show high specific surface areas and good compression strength.