Patent ID: 7968484

Claim:
A high-strength, fracture-resistant silicon nitride ceramic material comprising about 5 to about 75 wt-% of elongated reinforcing grains of beta-silicon nitride, wherein the elongated reinforcing grains have a major axis measuring about 1 micron or greater and an aspect ratio of 2:1 or greater; about 20 to about 95 wt-% of fine grains of beta-silicon nitride, wherein the fine grains have a major axis less than about 1 micron; and about 1 to about 15 wt-% of an amorphous intergranular phase comprising Si, N, O, a Lanthanide series element, and a secondary densification additive comprising a secondary densification element; wherein said elongated reinforcing grains are essentially isotropically oriented within a microstructure of the ceramic.