Fracture toughness and reliability of Si3N4 whisker-reinforced Si3N4 ceramics

Celio A. Costa, Judith Todd Copley

Research output: Contribution to journalConference article

Abstract

Addition of 5 and 10 wt.% Si3N4 whiskers to Si3N4 hot-pressed with 3% MgO resulted in an increase of toughness perpendicular to the hot-pressed direction of 25% (8.8 MPa.m1/2) and 14% (8.0 MPa.m1/2), respectively, compared to the monolithic material (7.0 MPa.m1/2). However, the same whisker additions to Si3N4 hot-pressed with 6% Y2O3 sintering aid, decreased the toughness of the composite by 18% (6.7 MPa.m1/2) and 10% (7.4 MPa.m1/2), respectively, compared to the monolithic material (8.2 MPa.m1/2). Despite the above differences in toughness, a Weibull modulus of 12 was found for all materials, irrespective of the amount of whiskers and type of sintering aids. Grain size variation did not uniquely explain the above differences in fracture toughness. A crack deflection mechanism predominated and could be correlated with the low value of Weibull modulus.

Original languageEnglish (US)
Pages (from-to)211-218
Number of pages8
JournalCeramic Engineering and Science Proceedings
Volume18
Issue number3 A
StatePublished - Jan 1 1997
EventProceedings of the 1997 21st Annual Conference on Composites, Advanced Ceramics, Materials, and Structures-B - Cocoa, FL, USA
Duration: Jan 12 1997Jan 16 1997

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All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Materials Chemistry

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