Microstructure and Mechanical Properties of Hot Isostatically Pressed Whisker Reinforced Si3N4 Ceramics

  • L. K. L. Falk
  • H. Björklund
  • J. E. Adlerborn
  • H. T. Larker


Si3N4 ceramics reinforced with SiC or β-Si3N4 whiskers and formed by HIP using the ABB Cerama glass encapsulation process have been characterized by analytical electron microscopy and x-ray diffractometry. Additions of 2.5 wt% Y2O3 and 0.2 wt% Fe2O3 as metal oxide sintering additives had a significant influence on matrix microstructure and the mechanical properties of the composites. The metal oxides promoted the development of a fibrous matrix which increased room temperature strength and indentation fracture toughness. However, the residual intergranular glass in these materials reduced high temperature strength. Whiskers added together with the metal oxides did not have any significant influence on toughness, while an addition of whiskers to the equiaxed microstructure of material formed without the sintering additives had a clear toughening effect.


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  1. 1.
    Becher P.F., Chun-Hway H., Angelini P. and Tiegs T.N., Toughening Behavior in Whisker-Reinforced Ceramic Matrix Composites. J. Am. Cer. Soc., 1988, 71, 1050–1061.CrossRefGoogle Scholar
  2. 2.
    Buljan S.T., Baldoni J.G. and Huckabee M.L., Si3N4-SiC Composites. Am. Cer. Soc. Bull., 1987, 66, 347–352.Google Scholar
  3. 3.
    Larker H.T. and Adlerbom J.E., Undoped and Low-doped Silicon Nitride with Whisker Reinforcement Made by Glass Encapsulated HIP. In Ceramic Materials and Components for Engines; Las Vegas, USA, Nov. 27-30, 1988, ed. V.J. Tennery, American Ceramic Society Inc., Westerville, Ohio, 1989, pp. 227–236.Google Scholar
  4. 4.
    Campbell, G.H., Rühle, M., Dalgleish, B.J. and Evans, A.G., Whisker Toughening: A Comparison Between Aluminium Oxide and Silicon Nitride Toughened with Silicon Carbide. J. Am. Ceram. Soc., 1990, 73, 521–30.CrossRefGoogle Scholar
  5. 5.
    Adlerbom J., Burstrom M., Hermansson L. and Larker H.T., Development of High Temperature High Strength Silicon Nitride by Glass Encapsulated Hot Isostatic Pressing. Mater & Design, 1987, 8, 229–232.CrossRefGoogle Scholar
  6. 6.
    Knutson-Wedel E.M., Falk L.K.L., Björklund H. and Ekstrom T., Si3N4 Ceramics Formed by HIP using Different Oxide Additions — Relation between Microstructure and Properties. Accepted for publication in J. Mater. Sci. Google Scholar
  7. 7.
    Lange F.F., Silicon nitride polyphase systems: fabrication, microstructure, and properties. Int. Met. Rev., 1980, No.1 Rev. 247, pp. 1–20.Google Scholar
  8. 8.
    Homeny J., Neergard L.J., Karasek K.R., Donner J.T. and Bradley S.A., Characterization of β-Silicon Nitride Whiskers. J. Am. Cer. Soc., 1990, 73, 102–105.CrossRefGoogle Scholar
  9. 9.
    Karasek K.R., Bradley S.A., Donner J.T., Martin M.R., Haynes K.L. and Yeh H.C., Composition and microstructure of silicon carbide whiskers. J. Mater. Sci., 1989, 24, 1617–1622.CrossRefGoogle Scholar
  10. 10.
    Tanaka I., Pezzotti G., Miyamoto Y. and Okamoto T., Fracture toughness of Si3N4 and its Si3N4 whisker composite without sintering aids. J. Mater. Sci., 1991, 26, 208–210.CrossRefGoogle Scholar

Copyright information

© Elsevier Science Publishers Ltd and MPA Stuttgart 1992

Authors and Affiliations

  • L. K. L. Falk
    • 1
  • H. Björklund
    • 1
  • J. E. Adlerborn
    • 2
  • H. T. Larker
    • 2
  1. 1.Department of PhysicsChalmers University of TechnologyGöteborgSweden
  2. 2.ABB Cerama ABRobertsforsSweden

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