Journal of the Ceramic Society of Japan
Online ISSN : 1882-1022
Print ISSN : 0914-5400
ISSN-L : 0914-5400
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Effect of Post-Sintering Heat-Treatment on Thermal Conductivity of Si3N4 Ceramics Containing Different Additives
Thanakorn WASANAPIARNPONGShigetaka WADAMasamitsu IMAIToyohiko YANO
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2005 Volume 113 Issue 1318 Pages 394-399

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Abstract

Silicon nitride ceramics were fabricated by dry pressing of a raw α-Si3N4 powder with Y2O3-SiO2 and Y2O3-Al2O3 as sintering aids, following by gas-pressured sintering at a temperature of 2123 K for 2 h under a nitrogen gas pressure of 1.0 MPa with Si3N4/BN packing powder. Subsequently, these specimens were heat-treated at a temperature up to 2223 K for 8 h under a nitrogen gas pressure of 1.0 MPa without any packing powder. Mass loss, density, oxygen content and thermal conductivity of the specimens before and after the post-sintering heat-treatment were measured. Due to the heat-treatment, the reduction of oxygen content, via the reaction of Si3N4 and SiO2, without decrease of relative density was found to be effective in improving thermal conductivity of the Si3N4 ceramics sintered with Y2O3-SiO2 additives. The effect of post-sintering heat-treatment was not significant for the Si3N4 specimen sintered with Y2O3-Al2O3 additives due to formation of SiAlON. Thermal conductivity of one of the former specimens reached 84 W/m•K at room temperature.

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© 2005 The Ceramic Society of Japan
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