Details

Autor(en) / Beteiligte

• Watari, Koji
• Hirao, Kiyoshi
• Brito, Manuel E.
• Toriyama, Motohiro
• Kanzaki, Shuzo
• WCA

Titel

Hot Isostatic Pressing to Increase Thermal Conductivity of Si3N4 Ceramics

Ist Teil von

• Journal of materials research, 1999-04, Vol.14 (4), p.1538-1541

Ort / Verlag

New York, USA: Cambridge University Press

Erscheinungsjahr

1999

Quelle

Springer Journals

Beschreibungen/Notizen

• Highly anisotropic Si3N4 ceramics were successfully fabricated by tape-casting of raw α–Si3N4 powders with β–Si3N4 single-crystal particles as seed particles and Y2O3 as an effective sintering aid, followed by hot isostatic pressing at a temperature of 2773 K for 2 h under a nitrogen gas pressure of 200 MPa. The microstructure consists of very large elongated grains (diameter ~10 μm; length of ~200 μm), highly oriented in the tape-casting direction. The thermal conductivity along this direction reaches 155 W m-1K-1 at room temperature, but varies significantly between room temperature and 1273 K. This thermal conductivity is closely related to (1) formation of extremely large elongated β–Si3N4 grains with a reduced amount of crystal defects due to the high-temperature firing and to (2) orientation of β–Si3N4 grains due to addition of seed particles and to tape-casting.