Accession Number : ADA194162
Title : Sinterable Ceramic Powders from Laser-Heated Gases.
Descriptive Note : Final rept. 1 Apr 82-31 May 86,
Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE ENERGY LAB
Personal Author(s) : Haggerty, John S
Report Date : Feb 1988
Pagination or Media Count : 155
Abstract : Extremely high quality ceramic powders have been synthesized from SiH4, NH3, and CH4 reactant gasses that are heated by absorbing energy emitted from a CO2 laser. Resulting Si, Si3N4 and SiC powders have been characterized in terms of parameters which are important for densification processes. The powders are virtually ideal. The fully dispersible powders have mean diameters ranging from 0.1-0.3 um with a standard deviation that is typically 25-45%. As synthesized powders are extremely high purity because the synthesis equipment is hermetic and cold-walled. The synthesis process has been modeled on a macro scale with respect to heat-transfer, fluid-flow and stability criteria. These results have permitted the process to be scaled safely to production rates up to 8-40 tons/year/nozzle. Keywords: Ceramic powder synthesis; Laser induced gas-phase reactions; Ceramic powder; Particle nucleation kinetics; Nitriding kinetics; Silicon carbide; Silicon nitride.
Descriptors : *CERAMIC MATERIALS , *GASES , *LASERS , *POWDERS , ENERGY ABSORBERS , HEAT , HEATING , HERMETIC SEALS , HIGH RATE , KINETICS , LOW TEMPERATURE , NITRIDING , NUCLEATION , PARAMETERS , PARTICLES , PHASE , PRODUCTION RATE , PURITY , REACTIVE GASES , SILICON CARBIDES , SILICON NITRIDES , STABILITY , STANDARD DEVIATION , SYNTHESIS(CHEMISTRY)
Subject Categories : Ceramics, Refractories and Glass
Distribution Statement : APPROVED FOR PUBLIC RELEASE