Effects of Process Zone and Specimen Geometry on Fracture Toughness of Silicon Nitride Ceramic

  • Shinji Yamauchi
  • Toshiro Kobayashi
Part of the Fracture Mechanics of Ceramics book series (FMOC, volume 10)


A precise fracture toughness testing method in ceramics should be established in an early period.

In the present study, requirements to obtain the valid fracture toughness values of sintered silicon nitride ceramic are examined in the static three point bending test and instrumented impact test. Moreover, it is generally considered that the toughness of ceramics is influenced by microcracking or phase transformation at a crack tip process zone. It is important, therefore, to understand and clarify the feature of process zone. Measurement of residual stress by X-ray method and transmission electron microscope(TEM) observation are carried out for this purpose.

It was shown that fracture toughness was not affected by crack length(a) to specimen width(W) ratio a/W and span length(S) to specimen width ratio S/W. However, the fracture toughness was affected by specimen thickness(B) and notch root radius(ρ). Static and dynamic fracture toughnesses increased with increasing the process zone size.

The valid fracture toughness value was obtained by precracked type specimen thicker than 4mm. This condition was represented by B≥70(KICmc)2, where σmc is a local critical fracture stress at the process zone.


Residual Stress Fracture Toughness Process Zone Notch Root Fracture Toughness Test 
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  1. (1).
    T. Kobayashi: Tetsu-to-Hagane,76(1990),149.Google Scholar
  2. (2).
    K.T. Faber and A.G. Evans: Acta Met.,31(1983),57.Google Scholar
  3. (3).
    T. Nose and T. Fujii: J.Am.Ceram.Soc.,71(1988),328.CrossRefGoogle Scholar
  4. (4).
    F. Wakai, S. Sakaguchi and Y. Matsuno: Yogyo-Kyokai-Shi, 93(1985),479.CrossRefGoogle Scholar
  5. (5).
    T. Kobayashi and M. Niinomi: Nuclear Eng.and Design, 111(1989),27.CrossRefGoogle Scholar
  6. (6).
    T. Kobayashi, K. Matsunuma, H. Ikawa and K. Motoyoshi: Eng.Frac.Mech.,31(1988),873.CrossRefGoogle Scholar
  7. (7).
    T. Mishima, Y. Nanayama, Y. Hirose and K. Tanaka: Zairyo (J.Mat.Sci.Japan)36(1987),805.Google Scholar
  8. (8).
    Y. Miyoshi: Zairyo(J.Mat.Sci.Japan) 37(1988),75.Google Scholar
  9. (9).
    H. Kishimoto, A. Ueno, H. Kawanoto and S. Kondo: Zairyo (J.Mat.Sci.Japan) 36(1987), 810.CrossRefGoogle Scholar
  10. (10).
    M. Koizumi, H. Yanagida: “The fundamental of ceramics” (in Japanese) vol.1,OHM,(1987).Google Scholar
  11. (11).
    A.G. Evans and R.W. Davidge: J.Am.Ceram.Soc.,5(1970),314.Google Scholar
  12. (12).
    F.E. Lange: J.Am.Ceram.Soc.,62 (1979),428.CrossRefGoogle Scholar
  13. (13).
    T. Kobayashi, Y. Koide, Y. Daicho and R. Ikeda: Eng.Frac. Mech.,28(1987),21.CrossRefGoogle Scholar
  14. (14).
    J.L. Kalthoff: Metals Handbook,8(1985,ASM),269.Google Scholar
  15. (15).
    G.R. Irwin: Appl.Mat.Res.,3(1964),65.Google Scholar
  16. (16).
    M. Sakai: Ceramics(in Japanese), 20(1985),33.Google Scholar
  17. (17).
    A.G. Evans: Mater.Sci.Res.,21(1986),775.Google Scholar
  18. (18).
    N. Miyata: Zairyo (J.Mat.Sci.Japan),37(1987),361.Google Scholar
  19. (19).
    F.E. Buresch: ASTM STP 678(1978),151.Google Scholar

Copyright information

© Springer Science+Business Media New York 1992

Authors and Affiliations

  • Shinji Yamauchi
    • 1
  • Toshiro Kobayashi
    • 1
  1. 1.Department of Production Systems EngineeringToyohashi University of TechnologyTempaku-cho,ToyohashiJapan

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