Preparation of graphite/nano-SiC composites by co-pyrolysis of a petroleum residue with phenylsilanes

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 1.0 MPa, 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 130 MPa of bending strength and 21 GPa of Young modulus.