Processing aerosols and filaments in a TM010 microwave cavity at 2.45 GHz

In this paper, as part of the development of generic microwave processes for spray-drying of homogeneous complex metal oxide powders and for inorganic fiber processing, the authors have investigated the use of 2.45 GHz microwaves in a high-Q single-mode TM010 cavity coupled directly to aerosols and fibers. Aqueous and ethanol aerosols of ferric nitrate solutions have been successfully dried at 1.8 kW of cavity power for a loaded O greater than 6000 in flowing nitrogen gas. Similarly, the authors have observed extremely rapid heating rates in the TM010 cavity for small-diameter confined cylinders of water and lossy inorganic fibers. These observations suggest using 2.45 GHz microwave power for drying, calcining, and sintering extruded ceramic filaments. Droplet modeling indicates that the large dielectric shielding for spherical droplets can significantly limit the coupling of 2.45 GHz microwave with spherical aerosols, but not with fibers. Experimental observations on the microwave interactions with ferric nitrate aerosols and with ceramic filaments in the TM010 cavity are described