Uncertainty of thermal diffusivity measurements by laser flash method

The laser-pulse method is a well-established nonsteady-state measurement technique for measuring the thermal diffusivity, a, of solid homogeneous isotropic opaque materials. BNM-LNE has developed its own bench based on the principle of this method in which the thermal diffusivity is identified according to the partial time moments method. Uncertainties of thermal diffusivity by means of this method have been calculated according to the ISO/BIPM Guide to the Expression of Uncertainty in Measurement. Results are presented for several cases (Armco iron, Pyroceram 9606) in the temperature range from 20 to 800 degrees C. The relative expanded (k = 2) uncertainty of the thermal diffusivity determination is estimated to be from +/- 3 to +/- 5%, depending on the material and the temperature.