Microwave caskets

In a microwave cavity loaded with a lossy dielectric material (such as a ceramic), the power is absorbed mainly by the casket (specimen enclosure) and the specimen. The losses in the cavity wall can typically be ignored such that Eq. (3) can be written as... 

For high-temperature microwave ceramic processing, the refractory specimen enclosure (the casket) serves as both i) a thermal insulator and ii) a microwave susceptor. The susceptor allows the microwave energy to couple with the material at high temperature. The thermal insulation diminishes the dissipation of thermal energy. On occasion, the caskets are referred to as susceptors, which does not fully depict the dual role of the specimen enclosure or casket as both a thermal insulator and a microwave susceptor (absorber). 

Ceramics used for thermal insulation of microwave caskets include alumina, aluminosilicates, mullite, and fused silica, each of which is relatively transparent to microwave radiation and thus have low dielectric loss at room temperature. The insulating materials included in the casket are typically in the form of ceramic fibers, fiberboard, or a granular bed of ceramic... 

Fig. 6 A schematic drawing of microwave casket (refractory specimen enclosure) composed of a hollow zirconia fiber-board material with disk-shaped aluminosilicate end caps.

Lee, K.Y. Case, E.D. Asmussen J., Jr. The steady-state temperature as a function of casket geometry for microwave-heated refractory caskets. Mater. Res. Innovations 1997, 1 (2), 101-116. 

Fig. 7.41 Schematic diagram of a microwave sintering with specially designed insulating casket Reproduced with permission from [151]. Copyright 2003, John Wiley Sons...

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