High-speed synchrotron X-ray imaging of glass foaming and thermal conductivity simulation

Glass foams are attractive thermal insulation materials, thus, the thermal conductivity (lambda) is crucial for their insulating performance. Understanding the foaming process is critical for process optimization. Here, we applied high-speed synchrotron X-ray tomography to investigate the change in pore structure during the foaming process, quantifying the foam structures and porosity dynamically. The results can provide guidance for the manufacturing of glass foams. The 3D pore structures were also used to computationally determine lambda. of glass foams using image-based modelling. We then used the simulated lambda to develop a new analytical model to predict the porosity dependence of lambda. The lambda values of the glass foams when the porosity is within 40% to 95% predicted by the new model are in excellent agreement with the experimental data collected from the literature, with an average error of only 0.7%, which performs better than previously proposed models. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.