Hostname: page-component-848d4c4894-75dct Total loading time: 0 Render date: 2024-05-14T15:54:49.123Z Has data issue: false hasContentIssue false
  • English
  • Français

Sinterability of Agglomerated Powders

Published online by Cambridge University Press:  21 February 2011

F.F. Lange
F.F. Lange*
Affiliation:
Rockwell International Science Center, Thousand Oaks, CA 91360
Get access

Abstract

Powdered compacts that do not have periodic, particulate arrangements exhibit nonperiodic density variations and are, by definition, agglomerated. The void phase in the compact can be separated into pores. The pore coordination number distribution and the critical coordinated number (Rc) governs the volume fraction of pores that can spontaneously disappear by diffusion, and therefore, the compact's sinterability. The pore coordination number distribution is favorably influenced by increasing the compact's initial density and decreasing the size of the multiple particle packing unit (for example, agglomerate size). During heating the pore coordination number distribution is unfavorably shifted by local sintering, which is produced by the spontaneous disappearance of pores with favorable coordination numbers (R < Rc). Local densification produces a dense, polycrystalline skefetal network. Grain growth during densification, supported by dense regions, favorably alters the coordination number of pores within the skeletal network and improves sinterability. The configuration and microstructure of the dense, skeletal network will control its compliance to deformation by either effective or applied (hot pressing) compressive stresses. Deformation of the dense, skeletal network will improve the coordination number distribution and thus sinterability. From this thinking, one concludes that the ideal situation requires either a periodic particle arrangement (which requires monodispersed powders), or lacking this arrangement, alterations in surface chemistry (or structure) such that Rc → ∞.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 24: Symposium B – Defect Properties and Processing of High-Technology Nonmetallic Materials , 1983 , 247
Copyright
Copyright © Materials Research Society 1984

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Exner, H.E., “Principles of Single Phase Sintering,” Reviews on Powder Metallurgy and Physical Ceramics 1, (1–4), T.1–251 (1979).Google Scholar
2. Haberko, K., “Characteristics and Sintering Behavior of ZrO2 Ultrafine Powders,” Ceramics Int'l. 5, 148 (1979).Google Scholar
3. Roosen, A. and Hausner, H., “Sintering Kinetics of ZrO2 Powders,” Proc. ZrO2 Conf., Stuttgart, June 1983.Google Scholar
4. Lange, F.F., “Sinterability of Agglomerated Ceramic Powders,” submitted to J. Ceram. Soc.Google Scholar
5. Lange, F.F. and Davis, B.I., “Sinterability of ZrO2 and Al2O3 Powders: The Role of Pore Coordination Number Distribution,“submitted to J. Ceram. Soc,Ref3.Google Scholar
6. Kingery, W.D. and Francois, B., “Sintering of Crystalline Oxides, I: Interaction Between Grain Boundaries and Pores,” in Sintering and Related Phenomena, eds., Kuzzynske, G.C., Hooten, N.A. and Gibbon, G.F., pp. 471 98, Gordon Breach, 1967.Google Scholar
7. Cannon, R.M., “The Effect of Dihedral Angle and Pressure on the Driving Forces for Pore Growth and Shrinkage,” to be published.Google Scholar
8. Vasilos, T. and Rhodes, W., “Fine Particulates to Ultrafine/Grain Ceramics,” in Ultrafine Grain Ceramics, eds. Durke, J.J., Reed, N.L. and Weiss, V., pp. 137–172, Syracuse Univ. Press, 1970.Google Scholar
9. Rhodes, W.H., “Agglomerate and Particle Size Effects on Sintering Yttria-Stabilized Zirconia,” J. Amer. Ceram. Soc. 64, 19 (1981).CrossRefGoogle Scholar
10. Gupta, T.K., “Possible Correlations Between Density and Grain Size During Sintering,” J. Amer. Ceram. Soc. 55 (5), 276 (1972).CrossRefGoogle Scholar
11. Lange, F.F. and Hirlinger, M., “Effect of ZrO2 Dispersion on the Grain Growth of Al2O3 ,” submitted to Amer. Ceram. Soc.Google Scholar
12. Lange, F.F., Yamaguchi, T. and Morgan, P.E.D., “Effect of ZrO2 Dispersion on the Sintering of Al2O3 ,” to be published.Google Scholar