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Abstract: Silicon-doped self-sintering carbons have been prepared by co-pyrolysis of an aromatic petroleum residue with silicon containing compounds (triphenylsilane or diphenylsilane) at 440°C and a pressure of 1.0MPa, with varying silicon content and soak time. Analysis of the solid pyrolysis products indicates that silicon inhibits mesophase formation and slightly accelerates the formation of material insoluble in 1-methyl-2-pyrrolidone (constituted by the heaviest molecules of the solid), especially when using the less substituted silane. The pyrolysis products have been extracted with toluene to obtain self-sintering carbon powders. The thermomechanical analysis of the self-sintering powders indicates that thermofusibility is restricted by the presence of silicon. By selecting the appropriate pyrolysis conditions it is possible to obtain heat-treated samples (2100°C) with density and mechanical properties superior to the undoped ones, reaching values of 130MPa of bending strength and 21GPa of Young modulus. [Copyright &y& Elsevier]

Abstract: The co-pyrolysis of a petroleum residue with two different sources of titanium (tetrabutyl-ortotitanate (TBO) or titanium carbide nano-powder) was carried out to obtain mesophase pitches containing TiO2 or TiC nanoparticles. Co-pyrolysis is an appropriate technique to achieve a good dispersion and low particle size. In the case of TBO, TiO2 nanoparticles (5–20nm) are observed, which are forming aggregates, the largest of them being 1–2μm. In the case of TiC nano-particles, they are more difficult to disperse and larger aggregates are formed, although the final material is rather homogenous. The chemistry of pyrolysis for the production of doped and undoped mesophase pitches has been followed by means of solvent insolubility, XRD, XPS, FTIR and elemental analysis. They show evidences of promotion of the formation of mesophase in the presence of the titanium-containing particles, especially in the presence of TiO2. The final materials can be of great value as precursors to produce high density titanium doped graphites for nuclear and space applications. [Copyright &y& Elsevier]