Claims
- 1. A Si3N4 sintered body produced by reactive sintering of silicon, said Si3N4 sintered body comprising crystal grains of Si3N4 and a grain boundary phase, wherein:an oxide (Ln2O3) of at least one element (Ln) selected from the group consisting of Y, Yb and Sm is contained in an amount of 0.6 to 13% by weight; an oxygen content in the crystal grains of Si3N4 is not more than 1% by weight; a molar ratio of SiO2/Ln2O3 in the Si3N4 sintered body is within a range of 0.1 to 0.8; and the Si3N4 sintered body has a relative density in the range of 85 to 99.99%, a thermal conductivity of at least 70W/m.K or more, and a three point bending strength of at least 600 MPa.
- 2. The Si3N4 sintered body according to claim 1, wherein said crystal grains of Si3N4 are a β-Si3N4 crystal having an average grain size of 2 μm or more in major axis, and a compound of LnaSibOcNd (wherein 2<a<4, 2<b<3, 0<c<7, 2<d<4) is contained in the grain boundary phase.
- 3. The Si3N4 sintered body according to claim 1, wherein said Ln2O3 and said Ln are Yb2O3 and YB, respectively.
- 4. The Si3N4 sintered body according to claim 3, wherein a compound Yb4Si2O7N2 is contained in the grain boundary phase.
- 5. The Si3N4 sintered body according to claim 1, wherein silicon powder is used as starting material of the Si3N4 sintered body.
- 6. A Si3N4 sintered body according to claim 1, wherein the Si3N4 sintered body is sintered at a temperature within 1700-1800° C.
Priority Claims (2)
Number |
Date |
Country |
Kind |
10-53281 |
Mar 1998 |
JP |
|
11-31009 |
Feb 1999 |
JP |
|
RELATED APPLICATIONS
This application claims priority from and is a continuation-in-part application of U.S. patent application Ser. No. 09/261,155, filed Mar. 3, 1999, now abandoned which is incorporated herein by reference.
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Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
09/261155 |
Mar 1999 |
US |
Child |
09/819986 |
|
US |