Compositions: ceramic – Ceramic compositions – Refractory
Reexamination Certificate
2011-06-28
2011-06-28
Group, Karl E (Department: 1731)
Compositions: ceramic
Ceramic compositions
Refractory
C501S097300, C264S683000
Reexamination Certificate
active
07968484
ABSTRACT:
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(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.
REFERENCES:
patent: 5120328 (1992-06-01), Pyzik
patent: 5312785 (1994-05-01), Pyzik et al.
patent: 5674793 (1997-10-01), Hirao et al.
patent: 5705449 (1998-01-01), Hirao et al.
patent: 5914286 (1999-06-01), Collin et al.
patent: 5922629 (1999-07-01), Park et al.
patent: 6066582 (2000-05-01), Collin et al.
patent: 6846765 (2005-01-01), Imamura et al.
patent: 7749932 (2010-07-01), Fukudome et al.
Ziegler et al., Interface Structure and Atomic Bonding Characteristics in Silicon Nitride Ceramics, submitted to Science, Oct. 12, 2004.
Becher et al, Temperature-Dependent Viscosity of SiREAl-Based Glasses as a Function of N:O and RE:Al Ratios (RE=La, Gd, Y and Lu) J. Am. Ceram. Soc., 87 [7] 1274-1279 (2004).
Becher Paul F.
Lin Hua-Tay
Group Karl E
Nelson Gregory A.
Novak Druce & Quigg LLP
UT-Battelle LLC
LandOfFree
Use of additives to improve microstructures and fracture... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Use of additives to improve microstructures and fracture..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Use of additives to improve microstructures and fracture... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2625699