An advanced method to manufacture hierarchically structured carbide-derived carbon monoliths

• Published in: Carbon (New York) 2014-04, Vol.70, p.30-37
• Main Authors: Fey, Tobias, Zierath, Bodo, Kern, Andreas M., Greil, Peter, Etzold, Bastian J.M.
• Format: Article
• Language: English
• Subjects: Carbides; Carbon; Ceramics; Channels; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Extraction; Fullerenes and related materials; diamonds, graphite; Materials science; Nanostructure; Physics; Porosity; Silicon carbide; Specific materials
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2013.12.052

The preparation of carbide-derived carbon (CDC) monoliths with a hierarchically structure in the nm and μm range is presented. Basis is the manufacturing of porous cellular SiC ceramics based on a biomorphous approach with μm porosity and subsequent conformal conversion to CDC by reactive extraction with chlorine. The SiC ceramics can be sintered at low temperatures and short times (1500°C, 2h) compared to classical preparation methods. The SiC ceramics show a macro pore volume (1–10μm channel size) of 0.56mlg−1, which corresponds to 1.5mlg−1 in the resulting CDC. The final carbon material exhibits an additional nano pore volume of 0.525mlg−1 with a mean slit pore size of 0.86nm. Mechanical stabilities of the highly porous CDC are excellent (bending strength 2.1±0.2MPa, corrected Weibull modulus 8.7, characteristic strength 2.2MPa and Youngs modulus 10.0±0.5GPa). The reactive extraction of the carbide monoliths shows very high reaction rates, approx. two dimensions faster (95×) compared to non-porous samples. Thus the manufacturing of the structured carbide and CDC can be performed at lower costs.