Thermal diffusivity measurement of semi-transparent materials with flash method

Aiming at the physical model inapplicability of flash method to measure thermal diffusivity of semi transparent materials, a new physical model was proposed. In the model, according to the permeance of materials, the pulse laser absorption of materials is of exponential type, and the authors establish a relevant differential equation and get a analytical form. On the laser heat conductivity apparatus, thermal diffusivities of AlN and ox horn samples were measured and the results were calculated with the orthogonal fitting method. The results show that the thermal diffusivity of two AlN samples are 0.482 cm 2·s -1 and 0.502 cm 2·s -1 and the thermal diffusivity of two ox horn samples are 1.38×10 -3 cm 2·s -1 and 1.40×10 -3 cm 2·s -1 respectively. The theoretical fitting curves are in agreement with the experimental data quite well, which shows that the theoretical model is suitable and accords with the experiment. When the absorption is close to the infinite, the model is transformed into Parker equation, which shows that this model is generally suitable, and the Parker equation is only a special case of this model. [