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Title: Use of additives to improve microstructures and fracture resistance of silicon nitride ceramics

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.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.

Inventors:
 [1];  [1]
  1. Oak Ridge, TN
Issue Date:
Research Org.:
UT-Battelle LLC/ORNL, Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1018720
Patent Number(s):
7968484
Application Number:
US Patent Application 11/851,540
Assignee:
UT-Battelle, LLC (Oak Ridge, TN)
Patent Classifications (CPCs):
C - CHEMISTRY C04 - CEMENTS C04B - LIME, MAGNESIA
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Becher, Paul F, and Lin, Hua-Tay. Use of additives to improve microstructures and fracture resistance of silicon nitride ceramics. United States: N. p., 2011. Web.
Becher, Paul F, & Lin, Hua-Tay. Use of additives to improve microstructures and fracture resistance of silicon nitride ceramics. United States.
Becher, Paul F, and Lin, Hua-Tay. Tue . "Use of additives to improve microstructures and fracture resistance of silicon nitride ceramics". United States. https://www.osti.gov/servlets/purl/1018720.
@article{osti_1018720,
title = {Use of additives to improve microstructures and fracture resistance of silicon nitride ceramics},
author = {Becher, Paul F and Lin, Hua-Tay},
abstractNote = {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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2011},
month = {6}
}

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