Cooling Time Constant Accuracy Dependence of Thermal Diffusivity Accuracy in Flash Method Analysis

Abstract

Cooling time constant method is widely used as the thermal diffusivity analysis method by flash method. In this method, the cooling time constant of the sample rear surface temperature data decrease region is used for the analysis and the thermal diffusivity accuracy depends on the cooling time constant accuracy. The expression relating the cooling time constant calculation region and the cooling time constant accuracy was derived. The dependence of the thermal diffusivity accuracy and biot number accuracy on the cooling time constant accuracy was derived. By using these equations, the dependence of the thermal diffusivity accuracy and biot number accuracy on the cooling time constant calculation region was confirmed. As for the accuracy of thermal diffusivity, the biot number and the cooling time constant, they are improved as the cooling time constant is calculated using backward data. The thermal diffusivity was analyzed by the cooling time constant method using theoretical temperature data and the dependency of the thermal diffusivity and biot number accuracy on the cooling time constant calculation region showed the same tendency as the result by the theoretical study. Biot number dependence of the cooling time constant calculation region where thermal diffusivity accuracy is 1% was obtained. It is desirable to calculate the cooling time constant behind this time region for thermal diffusivity analysis.