Effect of MgO Solute on Microstructure Development in Al2O3
The effect of MgO as a solid‐solution additive in the sintering of Al2O3 was studied. The separate effects of the additive on densification and grain growth were assessed. Magnesia was found to increase the densification rate during sintering by a factor of 3 through a raising of the diffusion rate....
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Veröffentlicht in: | Journal of the American Ceramic Society 1986-02, Vol.69 (2), p.143-149 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The effect of MgO as a solid‐solution additive in the sintering of Al2O3 was studied. The separate effects of the additive on densification and grain growth were assessed. Magnesia was found to increase the densification rate during sintering by a factor of 3 through a raising of the diffusion rate. The grain‐size dependence of the densification rate indicated control primarily by grain‐boundary diffusion. Magnesia also increased the grain growth rate during sintering by a factor of 2.5. The dependence of the grain growth rate on density and grain size suggested a mechanism of surface‐diffusion‐controlled pore drag. It was argued, therefore, that MgO enhanced grain growth by raising the surface diffusion coefficient. The effect of MgO on the densification rate/grain growth rate ratio was, therefore, found to be minimal and, consequently, MgO did not have a significant effect on the grain size/density trajectory during sintering. The role of MgO in the sintering of alumina was attributed mainly to its ability to lower the grain‐boundary mobility. |
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ISSN: | 0002-7820 1551-2916 |
DOI: | 10.1111/j.1151-2916.1986.tb04719.x |