Abstract
Porous mullite materials with high porosity of 71.8–88.2% were prepared by foaming of coal gangue/Al2O3/starch composite slurry and subsequent pore structure stabilization using starch consolidation and sintering. Coal gangue was recycled to prepare porous mullite foams. Starch was used as gellant, replacing commonly used poisonous chemical and expensive animal protein additives in foaming. Sintered mullite foams exhibited tri-modal pore structure, including large-sized pores (50–300 μm) replicating gas bubbles, moderate-sized pores (~10 μm) embedded in pore walls, and small-sized pores (<5 μm) appearing among mullite crystals. The compressive strength of mullite foams was between 0.21 and 8.7 MPa with low thermal conductivity between 0.1056 and 0.3848 W/m K, indicating that porous mullite foams are candidate materials for applications in thermal insulation.
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Acknowledgements
This work was supported by the Fundamental Research Funds for the Central Universities (2015XKZD01), National Natural Science Foundation of China (51574241), and the bilateral project of NSFC-STINT (51611130064). Farid Akhtar acknowledges Swedish Foundation for Strategic Research (SSF) for Infrastructure Fellowship grant No.RIF14-0083.
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Wang, Z., Feng, P., Geng, P. et al. Porous mullite thermal insulators from coal gangue fabricated by a starch-based foam gel-casting method. J Aust Ceram Soc 53, 287–291 (2017). https://doi.org/10.1007/s41779-017-0035-9
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DOI: https://doi.org/10.1007/s41779-017-0035-9