Ceramics-Silikáty 47, (3) 116 - 119 (2003) |
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THE EFFECT OF THE PbO ADDITION ON THE SINTERING OF ZnO
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Toplan H. Özkan 1, Erkalfa Hilkat 2, Özkan Osman T. 3
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1 The University of Sakarya, Engineering Faculty, Metallurgy and Materials Engineering Department,
Esentepe Campus, Adapazari, Turkey
2 TUBITAK, Marmara Research Centre, MCRI, PO Box 21, Gebze, Turkey
3 Istanbul University, Engineering Faculty, Avcilar-Istanbul, Turkey
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Keywords: Densification, Liquid Phase Sintering, ZnO grain growth
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The microstructural evolution and densification for the ZnO-PbO system were studied. Specimens were prepared by the
mixed oxide route, and sintered at temperatures in the range of 1000-1300°C. The bulk densities of the PbO-added ZnO
samples increased from 1000 to 1100°C. In sinterings above 1100°C, the bulk density was decreased almost linearly due to
lead oxide evaporation except in 2.5 mol% PbO-added ZnO samples. The ZnO-PbO ceramics have a two phase microstructure
comprising ZnO grains and a Pb-rich phase at the grain boundaries. The average grain size of ZnO increases with the
PbO addition up to 7.5 mol% PbO addition but, the excess PbO addition decreases the grain size. This is due to the change
in the grain growth mechanism from the solution precipitation in the liquid-phase to that of an ion diffusion mechanism in
a thicker layer of liquid. |
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