Hybrid Methodology for Retrieving Thermal Radiative Properties of Semi-Transparent Ceramics

International audienceSemitransparent materials, like silica or alumina, are highly used by high-temperature industries as refractory materials in blast or glass-making furnaces, first for their good mechanical properties. The knowledge of their radiative properties is also essential to improve thermal transfers. However, characterizing experimentally the high temperature dependence of radiative properties of semitransparent ceramic materials remains nowadays a difficult task. This paper reports a hybrid methodology to address this problem. The approach relies on two or more experimental emittance measurements, performed by infrared spectroscopy on samples of increasing thicknesses, and application of emittance models. The efficiency of the method is illustrated by using experimental data obtained on Jargal M samples, an industrial electrofused ceramic, and a virtual media built from X-ray computed tomography images. Two emittance models, a model from the literature and a new model proposed in this work, are selected to be a part of the hybrid methodology, since they allow retrieving complementary information on the optical and scattering properties of the materials. Both models show a good efficiency to reproduce emittance behavior of the industrial and virtual samples. Parameters are extracted from these models to improve our knowledge of the characteristic thickness of radiative transfer into semitransparent materials and the emittance value of semi-infinite media