Freeze-casting of highly porous cellulose-nanofiber-reinforced γ-Al2O3 monolithsHudelja, Hermina (Avtor) Konegger, Thomas (Avtor) Wicklein, Bernd (Avtor) Čretnik, Janko (Avtor) Akhtar, Farid (Avtor) Kocjan, Andraž (Avtor) cellulose nanofiberfreeze-castinggamma aluminahierarchical porosityinsulative materialsFreeze-casting is a powerful consolidation technique for the fabrication of highly porous and layered-hybrid materials, including ceramic-metal composites, and porous scaffolds for catalysis, bone substitutes and high- performance membranes. The aqueous suspensions to be freeze-casted usually contain dense particles facilitating macroporous, layered ceramics with dense (nonporous) struts. In the present study, hierarchical macro-mesoporous alumina (HMMA) monoliths were successfully prepared by freeze-casting of aqueous suspensions containing hierarchically-assembled, mesoporous γ‒Al2O3 (MA) powder and cellulose nanofibers (CNF). As- prepared monoliths were ultra-porous (93.1–99.2%), had low densities (0.01–0.25 g/cm3), and displayed relatively high surface areas (91–134 m2/g), but were still remarkably rigid with high compressive strengths (up to 52 kPa). Owing to the columnar porosity and mesoporous nature of the struts the freeze-casted HMMA monoliths exhibited high permeability and high thermal insulation, the latter ranging from 0.039 W/m∙K to 0.071 W/m∙K, depending on pore orientation.Elsevier Ltd20212022-11-30 12:15:54Neznano15855UDK: 620.3ISSN pri članku: 2666-5395DOI: 10.1016/j.oceram.2021.100069COBISS_ID: 51386371sl© 2021 The Author(s). Published by Elsevier Ltd on behalf of European Ceramic Society.