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Article Dans Une Revue Journal of the European Ceramic Society Année : 2011

Influence of H2/NH3 mixtures on the composition of SiCNYO and SiCNAl(O) nanopowders

Résumé

We performed pyrolysis of SiCNAlH and SiCNYOH nanopowder precursors under a reactive atmosphere (Ar/NH3/H2) with various compositions of ammonia (NH3) and dihydrogen (H2) to diminish C content, which is deleterious for thermal stability and sintering of the powders. This paper continues a previous work on the fabrication of an Si3N4/SiC composite without free C by studying the effect of H2 on the C/N atomic ratio of the powder. We studied the influence of the nature of the gaseous mixture (Ar/NH3/H2) on the powder composition. Elemental analysis showed that the introduction of H2 in the pyrolysis atmosphere limited the decomposition of NH3 and allowed for control of the C/N ratio. This behaviour can be explained by the structural evolution observed by 29Si NMR spectrometry but also by Fourier transform infrared and Raman spectroscopy. An Si3N4/SiC composite, with traces of free C, was obtained after post-pyrolysis heat treatment of the powders synthesized with 10 wt.% of H2 and 25 wt.% NH3.

Dates et versions

hal-00584300 , version 1 (08-04-2011)

Identifiants

Citer

S. Chehaidi, V. Salles, Sylvie Foucaud, Alexandre Maitre, P. Goursat. Influence of H2/NH3 mixtures on the composition of SiCNYO and SiCNAl(O) nanopowders. Journal of the European Ceramic Society, 2011, 31, pp.1113-1122. ⟨10.1016/j.jeurceramsoc.2010.12.026⟩. ⟨hal-00584300⟩
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