Advertisement

Journal of Materials Science

, Volume 30, Issue 21, pp 5495–5501 | Cite as

Microstructure and mechanical properties relations for green bodies compacted from spray dried granules

  • D. C. C. Lam
  • K. Kusakari
Papers

Abstract

Alumina granules from three binder systems were spray dried and pressed into bars at varied pressure. Granules are classified as strong, medium and weak as to reflect the different amount of poly(vinyl-butyral) binder and liquid paraffin plasticizer used in the binder system. Mechanical properties of the pressed bars were obtained from a four-point bend test and microstructures were examined using scanning electron microscopy SEM. Strengths and fracture toughnesses are found to increase as a function of compaction pressure, while the calculated effective flaw size is independent of the compaction pressure for all three granule types. Microstructural examination of fracture surfaces revealed that samples compacted at high pressure exhibited more transgranular fracture than samples compacted at low pressure. Evidently, higher pressure had increased the intergranular fracture resistance which correspondingly increased the fracture toughness of the pressed bars. For bars pressed from granules, green body strengths and toughnesses are strongly dependent on the cohesion between pressed granules and not on the effective processing flaw size.

Keywords

Fracture Toughness Flaw Size Intergranular Fracture Green Body Liquid Paraffin 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    L. M. Sheppard, Bull. Amer. Ceram. Soc. 72 (1993) 28.Google Scholar
  2. 2.
    S. P. Timoshenko and G. M. Gere “Mechanics of materials” (Van Nostrand Reinhold, New York, 1972) p. 288.Google Scholar
  3. 3.
    JIS R-1601 and JIS R-1602, Japan Industrial Standards, (Japan Industrial Standards Association 36 1991) p. 252 and p. 254.Google Scholar
  4. 4.
    D. Broek “Elementary engineering fracture mechanics” 4th Edn (Martinus Nijhoff, New York, 1986) p. 201.CrossRefGoogle Scholar
  5. 5.
    E. Klar and W. M. Shafer, in “Modern developments in powder metallurgy,” 9, edited by W. Leszynski (Metal Powder Industries Federation, Princeton, New Jersey, 1976) p. 91.Google Scholar
  6. 6.
    K. E. Easterling and A. R. Thölén, Powder Metall. 16 (1973) 112.CrossRefGoogle Scholar
  7. 7.
    E. Klar and W. M. Shafer, Int. J. Powder Metall. 5 (1969) 5, and 5 (1969) 5.Google Scholar
  8. 8.
    J. A. Lund, Int. J. Powder Technol. 18 (1982) 117.Google Scholar
  9. 9.
    A. G. Evans, B. J. Dalgleish, M. He and J. W. Hutchinson, Acta Metall. Mater. 37 (1989) 3249.CrossRefGoogle Scholar
  10. 10.
    A. G. Evans and B. J. Dalgleish, Ibid. 40 (Supplement) (1992) S-295.CrossRefGoogle Scholar
  11. 11.
    R. A. Dimilia and J. S. Reed, Bull. Amer. Ceram. Soc. 62 (1989) 484.Google Scholar
  12. 12.
    J. A. Brewer, R. H. Moore, and J. S. Reed, Ibid. 60 (1981) 212.Google Scholar
  13. 13.
    C. W. Nies and G. L. Messing, J. Amer. Ceram. Soc. 67 (1984) 301.CrossRefGoogle Scholar
  14. 14.
    M. Abdel-Ghani, J. G. Petrie, J. P. K. Seville, R. Clift and M. J. Adams, Powder Technol. 68 (1991) 113.CrossRefGoogle Scholar
  15. 15.
    M. J. Adams, J. Powder. Bulk Sol. Technol. 9 (1985) 15.Google Scholar
  16. 16.
    M. A. Mullier, J. P. K. Seville, M. J. Adams, Powder Technol. 65 (1991) 321.CrossRefGoogle Scholar
  17. 17.
    Idem., Chem. Eng. Sci. 42 (1987) 667.CrossRefGoogle Scholar

Copyright information

© Chapman & Hall 1995

Authors and Affiliations

  • D. C. C. Lam
    • 1
  • K. Kusakari
    • 2
  1. 1.Department of Mechanical EngineeringHong Kong University of Science and TechnologyKowloonHong Kong
  2. 2.Inorganic Materials Section, The 3rd Materials DepartmentHitachi Research LaboratoryIbaraki-kenJapan

Personalised recommendations