Papers

Journal of Materials Science

, Volume 26, Issue 5, pp 1333-1345

First online:

Conversion mechanisms of a polycarbosilane precursor into an SiC-based ceramic material

  • E. BouillonAffiliated withLaboratoire de Chimie du Solide du CNRS, Université de Bordeaux 1
  • , F. LanglaisAffiliated withLaboratoire de Chimie du Solide du CNRS, Université de Bordeaux 1
  • , R. PaillerAffiliated withLaboratoire de Chimie du Solide du CNRS, Université de Bordeaux 1
  • , R. NaslainAffiliated withLaboratoire de Chimie du Solide du CNRS, Université de Bordeaux 1
  • , F. CruegeAffiliated withLaboratoire de Spectroscopie Moléculaire et Cristalline, Université de Bordeaux 1
  • , P. V. HuongAffiliated withLaboratoire de Spectroscopie Moléculaire et Cristalline, Université de Bordeaux 1
  • , J. C. SarthouAffiliated withCentre d'Etudes Scientifiques et Techniques d'Aquitaine, CEA
  • , A. DelpuechAffiliated withCentre d'Etudes Scientifiques et Techniques d'Aquitaine, CEA
  • , C. LaffonAffiliated withLURE, Bt 209D, Université de Paris-Orsay
    • , P. LagardeAffiliated withLURE, Bt 209D, Université de Paris-Orsay
    • , M. MonthiouxAffiliated withLaboratoire Marcel Mathieu, Université de Pau
    • , A. OberlinAffiliated withLaboratoire Marcel Mathieu, Université de Pau

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Abstract

The pyrolysis of a PCS precursor has been studied up to 1600 °C through the analysis of the gas phase and the characterization of the solid residue by thermogravimetric analysis, extended X-ray absorption fine structure, electron spectrocopy for chemical analysis, transmission electron microscopy, X-ray diffraction, Raman and Auger electron spectroscopy microanalyses, as well as electrical conductivity measurements. The pyrolysis mechanism involves three main steps: (1) an organometallic mineral transition (550 < T p < 800 °C) leading to an amorphous hydrogenated solid built on tetrahedral SiC, Si02 and silicon oxycarbide entities, (2) a nucleation of SiC (1000 < T p < 1200 °C) resulting in SiC nuclei (less than 3 nm in size) surrounded with aromatic carbon layers, and (3) a SiC grain-size coarsening (T p > 1400 °C) consuming the residual amorphous phases and giving rise simultaneously to a probable evolution of SiO and CO. The formation of free carbon results in a sharp insulator-quasimetal transition with a percolation effect.