In-plane thermal diffusivity evaluation by infrared thermography

A thermographic technique for measuring the in-plane thermal diffusivity of slabs is presented; it consists of heating the front surface of a platelike sample by a circular Gaussian source. The in-plane thermal diffusivity is obtained by monitoring the time evolution of the spatial distribution of the rear surface temperature by an infrared camera. Specifically, from the temperature distribution taken at different times along a line crossing the heating image of the circular spot center on the rear surface, it is possible to obtain the time evolution of the radius of the Gaussian. In order to get the thermal diffusivity value from the widening of this radius, a method for the reduction of the experimental data is presented; the resulting in-plane thermal diffusivity value is then compared with the value found in the literature and with values furnished by the laser flash and the thermal wave interferometry experiments carried out on the samples extracted by the plate. Satisfactory agreement between all the values was noted.