Sintering of ZnO: II, Density Decrease and Pore Growth During the Final Stage of the Process*

Authors

  • T. K. GUPTA,

    1. Ceramics Division, Department of Metallurgy and Materials Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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    • Now senior engineer. Research and Development Center. Westinghouse Electric Corporation, Pittsburgh, Pennsylvania 15235.

  • R. L. COBLE

    1. Ceramics Division, Department of Metallurgy and Materials Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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  • Based on a thesis submitted by T. K. Gupta for the Doctor of Science degree in ceramics at the Massachusetts Institute of Technology.

  • Supported by the United States Atomic Energy Commission under Contract AT(30-1)-2574.

  • At the time this work was done, the writers were, respectively, research assistant and associate professor of ceramics, Department of Metallurgy and Materials Science, Massachusetts Institute of Technology.

  • *

    For Part I of this paper. see pp. 521-25, this issue.

Abstract

During the last stage of sintering of ZnO, a decrease in bulk density is accompanied by an increase in pore size and a decrease in the number of pores. Examination of the microstructures indicated that the pores are almost always situated at the grain boundaries and at the corners. The dominant pore size increases with time raised to the 1/3 power. The apparent diffusion coefficients calculated from the pore growth rate are in good agreement with lattice diffusivity for zinc. It is postulated that gas diffusion takes place along the boundaries during pore growth.

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