Comparative Evaluation of the Thermal Conductivity for Selected Materials Measured with a Laser Flash Apparatus and Other Techniques

摘要

The thermal conductivity of a wide selection of materials was determined. The materials include: limestone from different origin and its yielded lime, refractory materials -low density materials for insulation purposes, and high density materials for fire protection-, and powder-metallurgy steel sintered at various compression pressure. Each material was measured with two measuring techniques, which were suitable for the specific material. Systematic measurements of the thermal diffusivity were carried out with all materials by means of a laser flash apparatus until maximum 1500 °C. In order to obtain the thermal conductivity, the required specific heat capacity and thermal expansion were measured. The resulting conductivity was compared with the one directly obtained with a hot plate (steady state panel test method), a hot disk and a hot wire. The evaluation of the accuracy of the methods is presented as follows: Same sample measured several times with the same measuring technique, with the purpose to show the accuracy within the method. The evaluation of each method with different samples, in order to show the fluctuation of the conductivity inside the material. Finally, the deviation of the conductivity measurements among the different measurements techniques. Through this, it can be established whether the difference in the results may be attributed to the characteristics of material.