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Progress in Plasma Processing of Materials, 1999

ISBN:
1-56700-126-2 (Print)

NUMERICAL ANALYSIS OF Si POWDER EVAPORATION IN AXISYMMETRIC REACTOR WITH COAXIAL CONVERGENT NITROGEN PLASMA FLOW

Predrag Lj. Stefanovic
Institute of Nuclear Sciences "Vinca", Laboratory for Thermal Engineering and Energy, Mike Petrovica-Alasa 12-14, PO Box 522,11001 Belgrade, Yugoslavia

Dejan B. Cvetinovic
Institute of Nuclear Sciences "Vinca", Laboratory for Thermal Engineering and Energy, Mike Petrovica-Alasa 12-14, PO Box 522,11001 Belgrade, Yugoslavia

Pavle B. Pavlovic
The VINCA Institute of Nuclear Sciences, Laboratory for Thermal Engineering and Energy, P. O. Box 52211001 Belgrade, Yugoslavia

Zivota G. Kostic
Institute of Nuclear Sciences "Vinca", Department for Thermal Engineering and Energy Research -11001 Belgrade, PO Box 522, Yugoslavia

Abstract

For thermal plasma synthesis of Si3N4 or SiC ultrafine powder when Si powder is used as a precursor, pneumatic injection and mixing of solid particle with high temperature DC plasma flow presents very important problem. Paper presents result of numerical simulation of two plasma reactor schemes: 1. multi torch system reactor simulated by central Si powder injection and coaxial convergent nitrogen plasma flow and 2. Classical plasma reactor with central nitrogen plasma flow and axisymmetric radial injection of Si powder. Results of the numerical simulation of the analyzed example indicate that classical plasma reactor is much more suitable for plasma synthesis of Si3N4 and SiC ultrafine powders if parameters of Si powder injection can be optimized and controlled. The main reasons are: 1. higher silicon evaporation efficiency and 2. lower mass fraction (lower particle concentration) of unevaporated Si particles in the exit mixture in case of classical plasma reactor.