Preparation of ultrafine silicon nitride, and silicon nitride and silicon carbide mixed powders in a hybrid plasma

Journal Article · Thu Nov 01 04:00:00 EST 1990 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1990.tb06461.x· OSTI ID:5163063

Lee, H J; Eguchi, K; Yoshida, T ^[1]

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1. 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), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 73:11; ISSN JACTA; ISSN 0002-7820
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
CARBIDES
CARBON COMPOUNDS
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
DEPOSITION
NITRIDES
NITROGEN COMPOUNDS
PLASMA ARC SPRAYING
PNICTIDES
POWDERS
SILICON CARBIDES
SILICON COMPOUNDS
SILICON NITRIDES
SPRAY COATING
SURFACE COATING
SYNTHESIS