Effect of grain growth and measurement on fracture toughness of silicon nitride ceramics

Jianfeng Yang, Tohru Sekino, Koichi Niihara

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14 Citations (Scopus)


Two kinds of α-Si3N4 powders with different properties (high purity and low purity) were pressureless sintered using MgAl2O4-ZrO2 as sintering additives. The grain growth was controlled by sintering time and temperature. The fracture toughness was determined using indentation microfracture (IM) and single-edge-precracked-beam (SEPB) methods. A discrepancy of fracture toughness was found between the values obtained by these two methods, and the SEPB method provided higher fracture toughness than the IM method. Materials with more large elongated Si3N4 grains gave higher fracture toughness, R-curve behavior and larger discrepancy. This is contributed to the effects of grain bridging, pull-out and deflection by the large elongated Si3N4 grains. Comparing the specimens from two kinds of α-Si3N4 powders with different purity level, both gave high fracture toughness of over 9 MPa · m 1/2 by the SEPB method, while the E10 samples have a little higher flexural strength.

Original languageEnglish
Pages (from-to)5543-5548
Number of pages6
JournalJournal of Materials Science
Issue number22
Publication statusPublished - 1999 Dec 1

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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