ABSTRACT. Reliable and accurate temperature measurement during microwave processing of ceramic bodies is controversial. While thermocouples are routinely used in conventional thermal furnaces, their presence in microwave furnaces can locally distort the electromagnetic field; conduct heat away from the sample; induce thermal instabilities and microwave breakdown and lead to serious measurement errors. In this paper, these thermocouple effects were studied and were found to be more pronounced in low and medium loss ceramic materials. In order to reduce the thermocouple effects during the processing of advanced ceramic materials, an optical, noncontact temperature sensing system was developed, calibrated, and incorporated into a computer controlled microwave furnace.

This research was funded by the Structural Ceramics Division, Air Force Office of Scientific Research.

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