| 摘要 |
PROBLEM TO BE SOLVED: To obtain a silicon nitride sintered compact having high heat conductivity and high mechanical strength by adding a specified amt. of Columnar particles of single crystalline β-silicon nitride as seed crystals to a mixture of stock powder for silicon nitride and a sintering aid, forming a compact and carrying out epitaxial growth of columnar grains having a β-silicon nitride structure from the seed crystals as well as densification in nitrogen. SOLUTION: Columnar particles of single crystalline β-silicon nitride are added as seed crystals by 0.1-20 vol.%, a compact in which the seed crystals do not orient is formed and columnar grains having a β-silicon nitride structure are grown. The seed crystals preferably have 0.3-1 μm minor axis size and an aspect ratio of <=3. The resultant sintered compact has >=90 W/km heat conductivity in the thickness and longitudinal directions and >=800 MPa bending strength measured by a four-point bending method stipulated in JIS-R1601. The sintered compact is useful as a high temp. structural material or a high heat conduction substrate for a high temp. heat engine, a high temp. heat exchanger, a high temp. heat pipe, etc., requiring high heat conductivity and high mechanical strength. |
