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

Martin B. Østergaard, Manlin Zhang, Xiaomei Shen, Rasmus R. Petersen, Jakob König, Peter D. Lee, Yuanzheng Yue, Biao Cai - Department of Chemistry and Bioscience, Aalborg University, DK-9220 Aalborg East, Denmark - School of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT, United Kingdom - Advanced Materials Department, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia - Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, United Kingdom - Research Complex at Harwell, RAL, Didcot OX11 0FA, United Kingdom

Glass foams are attractive thermal insulation materials, thus, the thermal conductivity (λ) 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 λ of glass foams using image-based modeling. We then used the simulated λ to develop a new analytical model to predict the porosity dependence of λ. The λ 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.