Yttria doping and sintering of submicrometer-grained {alpha}-alumina
- Ecole Polytechnique Federale, Lausanne (Switzerland). Lab. de Ceramique
The sintering behavior of {alpha}-alumina powders doped with magnesia (500 or 1,500 ppm) and yttria (0, 500, or 1,500 ppm) was investigated using constant-heating-rate dilatometric experiments. The apparent activation energies for the intermediate stage of sintering were 740, 800, and 870 kJ/mol for 0, 500, and 1,500 ppm yttria doping levels, respectively; these were independent of magnesia doping. Yttria-doped powder compacts exhibited systematic anomalous second peaks in the densification rate curves at certain grain sizes which were determined only by yttria doping levels. Before the anomalous peak, with lower yttrium contents at grain boundaries, yttrium in an atomic state delays densification and raises the apparent activation energy. Beyond the peak, with higher yttrium contents at grain boundaries, yttria-rich precipitation delays the densification. Within the peak, yttrium segregation near the saturation level enhances densification.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 382464
- Journal Information:
- Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 8 Vol. 79; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
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