The Anisotropic Properties of the Tape Cast Si₃N₄ Ceramics with Rod-Like β-Si₃N₄ Seeds Addition

Abstract:

Lu2O3 and SiO2 were used as sintering additives and rod-like β-Si3N4 seeds were added to enhance β-Si3N4 grain unidirectional growth. Silicon nitride ceramics were prepared by tape casting and gas pressure sintering
at 1950oC in 10 atm nitrogen atmosphere for 6 h. Compare to the no-seeded Si3N4, the seeded and tape-cast Si3N4 ceramics have obvious anisotropic microstructure and anisotropic properties. When a stress applied along with the grain alignment direction, the bending strength of the seeded and tape-cast Si3N4 at 1500oC was 738 MPa, which was almost the same as its room temperature bending strength. However, the bending strength of the seeded and tape-cast at room temperature was 556 MPa (perpendicular direction); and their thermal conductivity were 67 W/m·K (perpendicular direction) and 83 W/m·K (parallel direction), respectively. The anisotropic properties of the seeded and tape-cast Si3N4 were attributable to the elongated Si3N4 grain alignment.

• Periodical: Key Engineering Materials (Volumes 317-318)
• Pages: 593-596
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.317-318.593
• Online since: August 2006
• Authors: Yu Ping Zeng, Naoki Kondo, Kiyoshi Hirao, Hideki Kita, Tatsuki Ohji, Shuzo Kanzaki
• Keywords: Bend Strength, Silicon Nitride Seed, Tape Casting, Thermal Conductivity (TC)

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