Preparation of ultrafine silicon nitride, and silicon nitride and silicon carbide mixed powders in a hybrid plasma
- Dept. of Metallurgy and Materials Science, Faculty of Engineering, Univ. of Tokyo, Tokyo 113 (JP)
This paper describes ultrafine Si{sub 3}N{sub 4} and Si{sub 3}N{sub 4} + SiC mixed powders synthesized through thermal plasma chemical vapor deposition (CVD) using a hybrid plasma which was characterized by the superposition of a radio-frequency plasma and an arc jet. The reactant, SiCl{sub 4}, was injected into an arc jet and completely decomposed in a hybrid plasma, and the second reactant, CG{sub 4} and/or NH{sub 3}, was injected into the tail flame through multistage ring slits. In the case of ultrafine Si{sub 3}N{sub 4} powder synthesis, reaction efficiency increased significantly by multistage injection compared to single-stage injection. The most striking result is that amorphous Si{sub 3}N{sub 4} with a nitrogen content of about 37 wt% and a particle size of 10 to 30 nm could be prepared successfully even at the theoretical NH{sub 3}/SiCl{sub 4} molar ratio of {approximately} 1.33, although the crystallinity depended on the NH{sub 3}/SiCl{sub 4} molar ratio and the injection method. For the preparation of Si{sub 3}N{sub 4} + SiC mixed powders, the N/C composition ratio and particle size could be controlled not only be regulating the flow rate of the NH{sub 3} and CH{sub 4} reactant gases and the H{sub 2} quenching gas, but also by adjusting the reaction space. The results of this study provide sufficient evidence to suggest that multistage injection is very effective for regulating the condensation process of fine particles in a plasma tail flame.
- OSTI ID:
- 5163063
- Journal Information:
- Journal of the American Ceramic Society; (United States), Vol. 73:11; ISSN 0002-7820
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SILICON CARBIDES
CHEMICAL VAPOR DEPOSITION
POWDERS
SILICON NITRIDES
PLASMA ARC SPRAYING
SYNTHESIS
CARBIDES
CARBON COMPOUNDS
CHEMICAL COATING
DEPOSITION
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
SILICON COMPOUNDS
SPRAY COATING
SURFACE COATING
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication