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

The preparation of carbide-derived carbon (CDC) monoliths with a hierarchically structure in the mu m and pm range is presented. Basis is the manufacturing of porous cellular SiC ceramics based on a biomorphous approach with pm 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 degrees C, 2 h) compared to classical preparation methods. The SiC ceramics show a macro pore volume (1-10 mu m channel size) of 0.56 ml g(-1), which corresponds to 1.5 ml g(-1) in the resulting CDC. The final carbon material exhibits an additional nano pore volume of 0.525 ml g(-1) with a mean slit pore size of 0.86 nm. Mechanical stabilities of the highly porous CDC are excellent (bending strength 2.1 +/- 0.2 MPa, corrected Weibull modulus 8.7, characteristic strength 2.2 MPa and Youngs modulus 10.0 +/- 0.5 GPa). The reactive extraction of the carbide monoliths shows very high reaction rates, approx. two dimensions faster (95x) compared to non-porous samples. Thus the manufacturing of the structured carbide and CDC can be performed at lower costs. (C) 2013 Elsevier Ltd. All rights reserved.