Vat photopolymerization 3D printing of thermal insulating mullite fiber-based porous ceramics

To satisfy the eagerness for mullite fiber-based porous ceramics (Mu(f)-based porous ceramics) with complex geometries in high-temperature thermal insulation fields, vat photopolymerization three-dimensional (3D) printing was first employed to prepare the highly complex Mu(f)-based porous ceramics. Herein, a photosensitive hydroxysiloxane HPMS-KH570 was employed as the resin matrix, which not only prevented the fiber agglomeration and improved the rheological properties of the slurries but also acted as a high-temperature binder to fix the fiber cross points after sintering and consequently improved the structural stability of the 3D-Mu(f)-based porous ceramics. The effects of mullite fiber (Mu(f)) aspect ratio and content on the performance of Mu(f) slurries, microstructure and physical properties of the 3D-Mu(f)-based porous ceramics were investigated. When the fiber aspect ratio was 45 and the fiber content was 6.67 vol%, the Mu(f) slurry exhibited the most suitable properties for vat photopolymerization 3D printing, and the corresponding 3D-Mu(f)-based porous ceramics exhibited a well-defined 3D printed lattice structure with struts consisting of randomly crisscrossing Mu(f). This unique 3D skeleton structure endowed the 3D-Mu(f)-based porous ceramics with low density (0.47 g/cm(3)) and low room temperature thermal conductivity (0.11 W/(m.K)), enabling it a promising candidate for high-temperature (1000-1400 degrees C) insulation materials. Furthermore, this printing strategy provided references for vat photopolymerization 3D printing of other fiber-based materials.