A practical analysis to predict sample overheating in flash experiments using the current ramp methodology

Abstract

This work presents a straightforward strategy for achieving specific overheating during flash experiments by adjusting the initial electrical parameters. To do that, an extensive experimental analysis was performed to evaluate the temperature evolution of dense ZnO specimens during controlled-current ramping at different furnace temperatures, which in turn modified the initial electrical resistance of the sample. A detailed electrical explanation of controlled-current ramp flash processes is provided and, for the first time, a practical equivalence between current-ramp and temperature-ramp flash methodologies is established. By parameterizing the experiments in terms of an effective power density, a consistent heating pattern following the blackbody radiation trend was identified, despite the different electrical characteristics of each experiment. Finally, a “flash heating map” is introduced, which can be used to determine the starting electrical parameters necessary to achieve a specific temperature increase, whether employing current or temperature ramps.