It is more than forty years since Parker et al (1961, working for the US Navy Radiological Defense Laboratory, released their original paper introducing the flash technique. Since then this photothermal experimental method has been extended worldwide and it has become the most popular method for the measurement of the thermal diffusivity of solids. The simplicity and the efficiency of the measurement, the accuracy and the reliability of results, and possibilities of application under a wide range of experimental conditions and materials are the main advantages of the flash method. The fact that the flash method has received standard status in many countries acknowledges its universality.We present an up-to-date summary of the theory and application of the flash method. We discuss the ideal adiabatic model and non-ideal models that account for the influence of the main disturbing phenomenaö heat losses from the sample, finite heat pulse durations, and nonuniform heating effects. The paper focuses on the survey of data-reduction methodsö algorithms for calculation of thermal diffusivity from the experimental data. It provides also references to several original papers with descriptions of the experimental apparatus. Attention is given to applications of the flash method for the measurement of advanced materialsösemitransparent media, materials with significant dependence of their thermophysical properties on temperature, anisotropic materials, layered structures, thin films, and composites. The paper contains a short note about various experimental methods having their origin in the flash method.

No abstract

The paper deals with the uncertainty analysis for thermal diffusivity measurements using the laser flash method. A general metrological characterization of the high temperature thermal diffusivity measurement apparatus has been carried out. The metrological investigation follows the general rules for the evaluation and expression of uncertainty in measurement. This work presents a brief introduction to the flash method. It summarizes the main disturbing phenomena that may significantly influence the accuracy of the thermal diffusivity measurement. It gives a detailed description of the high temperature laser flash experimental apparatus installed at Austrian Research Centers. The paper also gives results of test measurements of the thermal diffusivity of a standard material, i.e., austenitic steel X10NiCrMoTiB1515 in the temperature range 20-900 • C. The results are compared with literature data and discussed. Sources of measurement errors are analyzed; components of uncertainty are categorized according to their evaluation method. The results are subjected to rigorous statistical evaluation to determine the uncertainty associated with thermal diffusivity measurements.

No abstract

No abstract