A PTB foil sensor accurately and reliably measures both thermal conductivity and thermal diffusivity in just a few minutes and in one single step. It even determines the directional dependence of these two material parameters – simultaneously and in all three spatial directions. In order to perform a measurement, the sensor is simply laid between two halves of the sample. The sensor consists of three individual measuring probes which are integrated into the foil sensor and arranged at a right angle. The measuring probe in the centre induces a heat flow of known rate into the sample. Similar to the other two – purely passive – measuring probes, it detects the temperature increase during the time of measurement. The three directional components of thermal conductivity and thermal diffusivity can be easily determined from the three temperature variations. Thanks to the new sensor, time-consuming multiple measurements are a thing of the past. Developing new materials, e.g., more efficient insulation materials in the construction industry, is thus becoming less costly.
ulf.hammerschmidt