Journal of Materials Science

, Volume 16, Issue 3, pp 787–799 | Cite as

Effect of CeO2, MgO and Y2O3 additions on the sinterability of a milled Si3N3 with 14.5 wt% SiO2

  • Alan Arias
Papers

Abstract

Specimens of milled α-Si3N4 with 0 to 5.07 equivalent per cent of CeO2, MgO or Y2O3 additions were pressureless sintered at 1650 to 1820° C for 4 h in static nitrogen at 34.5 kPa (5 psi) gauge pressure and while covered with a mixture of Si3N4+SiO2 powders. The density — per cent addition — temperature plots showed maxima which, for all three additives, occurred between ∼ 1.2 and 2.5 equivalent per cent. Maximum densities resulted on sintering in the 1765 to 1820° C range and were 99.6 per cent of theoretical with 2.5 equivalent per cent CeO2, 98.5 per cent of theoretical with ∼ 1.24 to 1.87 equivalent per cent MgO, and 99.2 per cent of theoretical with 2.5 equivalent per cent Y2O3. Also, densities ≥ 94 per cent of theoretical were obtained with as little as 0.62 equivalent per cent additive (1.0 MgO, 2.11 CeO2 or 1.85 Y2O3, in wt%). X-ray diffraction showed that the materials were predominantly β-Si3N4 with some or no Si2N2O. Scanning electron photomicrographs showed microstructures of elongated grains with aspect ratios of about 5, with all additives.

Keywords

Nitrogen Polymer Microstructure SiO2 Aspect Ratio 

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References

  1. 1.
    K. H. Jack and W. I. Wilson, Nature 328 (1972) 28.Google Scholar
  2. 2.
    R. R. Wills, J. Amer. Ceram. Soc. 58 (1975) 335.Google Scholar
  3. 3.
    G. R. Terwilliger and F. F. Lange, J. Mater. Sci. 10 (1975) 1169.Google Scholar
  4. 4.
    M. Mitomo, M. Tsutsumi, E. Bannai and T. Tanaka, Amer. Ceram. Soc. Bull. 55 (1976) 313.Google Scholar
  5. 5.
    I. Oda, M. Kaneno and N. Yamamoto, in “Nitrogen Ceramics”, edited by F. L. Riley (Noordhoff, Leyden, 1977) p. 359.Google Scholar
  6. 6.
    A. W. J. M. Rae, D. P. Thompson and K. H. Jack, in “Ceramics for High Performance Applications II”, edited by J. J. Burke, E. N. Lenoe and R. N. Katz (Brook Hill, Massachus., 1978), p. 1039.Google Scholar
  7. 7.
    J. T. Smith, Sixteenth Highway Vehicles Systems Contractor's Co-ordination Meeting, CONF-7904105, April, 1979, Dearborn, USA, (US Dept. of Energy, Washington, 1979) p. 171.Google Scholar
  8. 8.
    S. Prochazka and C. D. Greskovich, “Development of a Sintering Process for High-Performance Silicon Nitride”, AMMRC TR 78-32, Army materials and Mechanics Research Centre, U.S.A. (1978).Google Scholar
  9. 9.
    A. Arias, J. Mater. Sci. 14 (1979) 1353.Google Scholar
  10. 10.
    J. L. Iskoe, F. F. Lange and E. S. Diaz, Ibid. 11 (1976) 908.Google Scholar
  11. 11.
    G. Q. Weaver and J. W. Lucek, Amer. Ceram. Soc. Bull. 57 (1978) 1131.Google Scholar
  12. 12.
    A. Arias, “Effect of Oxygen to Nitrogen Ratio on Sinterability of Sialons”, NASA Report TP 1382 (1979).Google Scholar
  13. 13.
    L. J. Gauckler and G. Petzow, in “Nitrogen Ceramics” edited by F. L. Riley (Noordhoff, Leyden, 1977) p. 41.Google Scholar
  14. 14.
    A. Arias, “Effect of Oxide Additions and Temperature on the Sinterability of milled α-Si3N4”, NASA Report TP-1644 (1980).Google Scholar
  15. 15.
    I. C. Huseby and G. Petzow, Powder Metall. Int. 6 (1974) 17.Google Scholar
  16. 16.
    F. F. Lange, Amer. Ceram. Soc. Bull. 59 (1980) 239.Google Scholar
  17. 17.
    K. H. Jack, J. Mater. Sci. 11 (1976) 1135.Google Scholar
  18. 18.
    G. Himsolt, H. Knoch, H. Huebner and F. W. Kleinlein, J. Amer. Ceram. Soc. 62 (1979) 29.Google Scholar
  19. 19.
    F. F. Lange, ibid. 61 (1978) 53.Google Scholar
  20. 20.
    F. F. Lange, S. C. Singhal and R. C. Kuznicki, ibid. 60 (1977) 249.Google Scholar

Copyright information

© Chapman and Hall Ltd 1981

Authors and Affiliations

  • Alan Arias
    • 1
  1. 1.Lewis Research CentreClevelandUSA

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