The Effect of Microstructure on Fracture Toughness for Silicon Nitride Ceramics

J. Yang, T. Sekino, K. Niihara

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1 Citation (Scopus)


Effect of microstructure on the fracture toughness for Si3N4 ceramics were studied. The Si3N4 ceramics were fabricated by pressureless sintering using two kinds of Si3N4 powders (high purity powder: E10, and relatively low purity powder: 9S) as starting powders. Grain growth of β-silicon nitride was controlled by keeping time and sintering temperature. The fracture toughness was measured by indentation fracture (IF) method and single-edge-precracked-beam (SEPB) method. There was a discrepancy between the fracture toughness values obtained by these two methods. From this study it was found that the materials with more large elongated Si3N4 grains gave higher fracture toughness, R-curve behavior and large discrepancy. This was contributed to the effects of grain bridging, pull-out and deflection by large elongated Si3N4 grains. Comparing the specimens fabricated from the E10 and 9S powders, both reached high fracture toughness over 9 MPa·m1/2 by the SEPB method.

Original languageEnglish
Pages (from-to)195-198
Number of pages4
JournalKey Engineering Materials
Publication statusPublished - 1999 Jan 1
Externally publishedYes


  • Fracture Toughness
  • Grain Growth
  • Silicon Nitride

ASJC Scopus subject areas

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


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