Evaluation of the Thermal Diffusivity of Thin Specimens from Laser Flash Data

Thermal-diffusivity data obtained by a pulse technique are substantially in error if the sample thickness becomes too small. In this case the inevitable spike caused by the trigger pulse for the laser and the thermogram of the specimen are interacting, and a superposition of both signals is recorded, whose evaluation with standard algorithms systematically underestimates the thermal diffusivity of materials. Therefore, this incorrect calculation corresponding to the spike-thermogram overlay was investigated for general tendencies, and a calculation method transferring the experimental data obtained for small thicknesses into representative thermal diffusivity values for the investigated material will be introduced.