Microwave sintering of alumina at 2.45 GHz

Kristen H. Brosnan, Gary L. Messing, Dinesh K. Agrawal

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The sintering kinetics and microstructural evolution of alumina tubes (∼17 mm length, ∼9mm inner diameter, and ∼11 mm outer diameter) were studied by conventional and microwave heating at 2.45 GHz. Temperature during microwave heating was measured with an infrared pyrometer and was calibrated to ±10°C. With no hold at sintering temperature, microwave-sintered samples reached 95% density at 1350°C versus 1600°C for conventionally heated samples. The activation energy for microwave sintering was 85 ± 10 kJ/mol, whereas the activation energy for conventionally sintered samples was 520 ± 14 kJ/mol. Despite the difference in temperature, grains grew from ∼1.0 μm at 86% density to ∼2.6 μm at 98% density for both conventional sintered and microwave-sintered samples. The grain size/density trajectory was independent of the heating source. It is concluded that the enhanced densification with microwave heating is not a consequence of fast-firing and therefore is not a result in the change in the relative rates of surface and grain boundary diffusion in the presence of microwave energy.

Original languageEnglish (US)
Pages (from-to)1307-1312
Number of pages6
JournalJournal of the American Ceramic Society
Issue number8
StatePublished - Aug 2003

All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Materials Chemistry


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