A main application area of ceramic open‐cell foams is the foundry, where the porous media are used for conditioning and filtration of the melt flow. As characterization of heat transfer in such high‐temperature applications requires consideration of thermal radiation, knowledge of the radiative properties of the foams is essential. Instead of elaborative measurements or simulations, empirical correlations often serve as a simple and fast method to predict extinction coefficients. However, significant differences up to 100 m−1 occur between calculated values of various models presented in the literature. Herein, it is aimed to characterize the radiation behavior of different ceramic foams experimentally and identify reliable, simple yet accurate methods for the prediction of extinction coefficients of these materials by comparison with experimental results. The influences of pore density (10 and 20 pores per inch [ppi]) and filter material (Al2O3, ZrO2, SiC, Al2O3−C) on the transmittance, reflectance, and extinction coefficients are investigated by spectroscopic measurements. Two models from the literature are determined, which are well suited to predict extinction coefficients with an average deviation of less than 20%. Furthermore, accurate estimation with an average deviation of 12% can be also achieved using a projection method based on computed tomography scans of the foams.

The Hot Disk method is a transient measurement method for the determination of thermal properties like the thermal conductivity, which is characterized by advantages such as a short measurement time or a low effort for the sample preparation. However, some difficulties related to measurements at elevated temperatures, which could be attributed to inaccuracies of the Temperature Coefficients of Resistance (TCRs), have been pointed out in the past. This paper presents a detailed investigation of the Hot Disk method for the determination of the thermal conductivity and contributes to a further improvement of its measurement accuracy. Subsequent to an extensive literature review of available reference materials for the thermal conductivity, measurements up to 750 °C were carried out with a Hot Disk TPS 2500 S with various Kapton and Mica sensors using three reference materials (Silcal 1100, Pyroceram 9606, Inconel 600). While room-temperature measurements confirmed the suitability of the reference samples as well as the independence of the measured thermal conductivity from the sensor, temperature-dependent measurements allowed the verification of the accuracy of the given TCRs. A set of optimized TCRs is proposed, with which the thermal conductivity of all three reference materials could be determined with an accuracy of 2 %. Furthermore, the measurement uncertainty of ± 5 % specified by the manufacturer could be confirmed. Hence, with the newly suggested TCRs, the Hot Disk method enables the determination of the thermal properties of a variety of materials even at high temperatures with high accuracy.