Effect of Heat-Treatment on Thermal and Mechanical Properties of Silicon Nitride Ceramic at Room and High Temperatures

Alpha-silicon nitride powder with the SiO2-Mg0-Y2O3 system as sintering additives was pressurelessly sintered at 1650 deg C for 2 h in atmospheric N2. Subsequently, these specimens were heat-treated at 1950 deg C for 8 h under N2 gas pressure of 1.0 MPa to eliminate grain boundary phase. The oxygen...

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Bibliographic Details
Published in:Key engineering materials 2007-01, Vol.352, p.35-39
Main Authors: Imai, Masamitsu, Wasanapiarnpong, Thanakorn, Sekimoto, Yuki, Yano, Toyohiko, Katayama, Keiichi
Format: Article
Language:English
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Summary:Alpha-silicon nitride powder with the SiO2-Mg0-Y2O3 system as sintering additives was pressurelessly sintered at 1650 deg C for 2 h in atmospheric N2. Subsequently, these specimens were heat-treated at 1950 deg C for 8 h under N2 gas pressure of 1.0 MPa to eliminate grain boundary phase. The oxygen content in these specimens was reduced by reactions of Si3N4 and the sintering additives during the heat-treatment. Thermal conductivity in 3mass%SiO2-3mass%Mg0-6mass%Y2O3-added Si3N4 specimen was improved from 36.6 W/m ? K to 90.4 W/m ? K by decreasing the amount of grain boundary phase after the heat-treatment. Bending strength of the sintered bodies both before and after the heat-treatment was sustained more than 550 MPa up to 1200 deg C.
ISSN:1013-9826
1662-9795
1662-9795
DOI:10.4028/www.scientific.net/KEM.352.35