Introduction of micro-nano bubbles in kaolin foams to facilitate the preparation of porous ceramics

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In this study, a novel foam-gelcasting method employing a micro-nano bubble generator was developed to fabricate porous ceramics using kaolin as raw material. The effects of three types of water including normal water (NW), water with added micro-nano bubbles (WMB), surfactant-modified water with added micro-nano bubbles (SWMB) on the preparation of porous ceramics were compared, and the microstructure and properties of the prepared porous ceramics were characterized. Porous ceramics prepared with SWMB exhibited smaller, more uniform pore sizes, achieving an average pore diameter of 77.4 μm. The microstructure analysis revealed enhanced uniformity and stability due to the effective integration of micro-nano bubbles. The compressive strength of ceramics prepared with SWMB increased significantly, with better resistance to deformation and rupture. Additionally, the finer pore structure suppressed convective heat transfer, while the presence of micro-nano pores within the pore walls decreased the heat conduction of the solid skeleton, allowing the sample to maintain low thermal conductivity even at reduced porosity. This work provides a new idea for the preparation of porous ceramics by the slurry foaming method. Porous ceramics with enhanced mechanical properties and smaller pore size are produced by using stable micro-nano bubbles.