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Nanosized Si-C-N-Powders by Polysilazane-Pyrolysis and Si3N4/SiC Composite materials thereof

Nanoskalige Si-C-N-Pulver durch Polysilazan-Pyrolyse und Si3N4-Werkstoffe aus diesen
: Boden, G.; Neumann, A.; Breuning, T.; Tschernikowa, E.; Hermel, W.


Journal of the European Ceramic Society 18 (1998), Nr.9, S.1461-1469
ISSN: 0955-2219
Fraunhofer IKTS ()
gasphase reaction; nanocomposite; organic precursors; Siliconcarbonitride Powders; thermal properties

Nanosized silicon carbonitridepowders have been synthesized by gasphase pyrolysis of evaporable precursors at temperatures between 600 and 1000 deg C.These synthesis have been carried out by using of mixtures of cyclic polysilazanes,which were prepared by ammonolysis of dimethyldichlorosilane as starting materials.The spheric powder particles are X-amorphous.They demonstrate a particle size from 100 to 600nm and a specific surface area from 10 to350m2/g.The Si-C-N-Powders crystallize upper 1400 deg C to Si3N4 and S iC-phases.By pyrolysis or post heating in reactive ammonia gas the carbon content can be diminished.The thermogravimetric investigationes indicate,that after the pyrolysis organic species are adsorbed onto the surface of the powders,which can be removed by suitable post.treatment.From the synthesized Si-C-N-powders Si3N4/SiC-composite materials have been obtained by sintering.Inthese composites SiC nanograins are arranged both in the intra-and inthe intertype and hinder the growth of the Si3N4.grains.