A SIMPLE NONINVASIVE OPTICAL PYROMETRIC METHOD FOR PLOTTING TEMPERATURE TIME PROFILES OF HIGH-TEMPERATURE REACTIONS IN MICROWAVE-OVENS

A simple optical pyrometric method is described, based on a photocell with red and blue filters calibrated by the disappearing filament tech nique. The method, which is cheap, non-invasive and reproducible, is u sed for measurement of the rate of heating of solid materials such as coke, CuO or Fe3O4 in a microwave oven. All materials were heated unde r dinitrogen in a silica reaction vessel over 3 min in a 650 W oven. C oke (which contains graphitic phases) and magnetite heat smoothly to m aximum temperatures of 1180 and 1050-degrees-C respectively. CuO heats erratically with plasma discharges from the surface, however when cov ered with a layer of coke the oxide heats smoothly achieving a maximum temperature of 1210-degrees-C. The observations are discussed.