Use of additives to improve microstructures and fracture resistance of silicon nitride ceramics
- Oak Ridge, TN
A high-strength, fracture-resistant silicon nitride ceramic material that includes about 5 to about 75 wt-% of elongated reinforcing grains of beta-silicon nitride, about 20 to about 95 wt-% of fine grains of beta-silicon nitride, wherein the fine grains have a major axis of less than about 1 micron; and about 1 to about 15 wt-% of an amorphous intergranular phase comprising Si, N, O, a rare earth element and a secondary densification element. The elongated reinforcing grains have an aspect ratio of 2:1 or greater and a major axis measuring about 1 micron or greater. The elongated reinforcing grains are essentially isotropically oriented within the ceramic microstructure. The silicon nitride ceramic exhibits a room temperature flexure strength of 1,000 MPa or greater and a fracture toughness of 9 MPa-m.sup.(1/2) or greater. The silicon nitride ceramic exhibits a peak strength of 800 MPa or greater at 1200 degrees C. Also included are methods of making silicon nitride ceramic materials which exhibit the described high flexure strength and fracture-resistant values.
- Research Organization:
- UT-Battelle, LLC (Oak Ridge, TN)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-00OR22725
- Assignee:
- UT-Battelle, LLC (Oak Ridge, TN)
- Patent Number(s):
- 7,968,484
- Application Number:
- US Patent Application 11/851,540
- OSTI ID:
- 1018720
- Country of Publication:
- United States
- Language:
- English
Temperature-Dependent Viscosity of SiREAl-Based Glasses as a Function of N:O and RE:Al Ratios (RE = La, Gd, Y, and Lu)
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journal | July 2004 |
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