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Strength and microstructure of sintered Si3N4 with rare-earth-oxide additionsRoom temperature, 700-, 1000-, 1200-, and 1370-C examinations of the effect of 1.7-2.6 mol pct rare earth oxide additions to sintered Si3N4 are conducted. While the room temperature-1000 C bend strengths were higher for this material with Y2O3 additions than with CeO2, La2O3, or Sm2O3, the reverse was true at 1200-1370 C. This phenomenon is explained on the basis of microstructural differences, since quantitative microscopy of SEM replicas showed the Si3N4-Y2O3 composition to contain both a higher percentage of elongated grains and a coarser microstructure than the other three alternatives. The elongated grains appear to increase this composition's low temperature strength irrespective of microstructural coarseness; this coarseness, however, decreases strength relative to the other compositions at higher temperatures.
Document ID
19850043120
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Sanders, W. A.
(NASA Lewis Research Center Cleveland, OH, United States)
Mieskowski, D. M.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 12, 2013
Publication Date
February 1, 1985
Publication Information
Publication: American Ceramic Society Bulletin
Volume: 64
ISSN: 0002-7812
Subject Category
Nonmetallic Materials
Report/Patent Number
ACS PAPER 130-13-84
Accession Number
85A25271
Distribution Limits
Public
Copyright
Other

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