Porous mullite fiber-based ceramics inspired by biomimetic natural pine wood

How to further improve the strength of fiber porous ceramics has always been the focus of researchers. Herein, inspired by the unique microstructure of natural woods which exhibit excellent mechanical and thermal insulation properties, a high strength mullite fiber-based porous ceramic with wood-like microstructure was successfully designed and fabricated. The wood-like porous ceramics were mainly composed of two kinds of layered structures that are perpendicular to each other. The horizontally oriented lamellar structure was constructed by assembling the fiber membranes layer by layer, and the vertically oriented lamellar structure perpendicular to the fiber layer was constructed by the directional freeze casting method. The results indicated that as to the mullite fiber-based porous ceramics with the similar density (∼0.36 g/cm3), the compressive strength along the X-axis direction of porous ceramics with wood-like microstructure prepared by the directional freeze casting method (3.4 MPa) was much higher than that of porous ceramics prepared by the non-directional freeze casting method (1.04 MPa), owing to the formation of silica lamellar structure perpendicular to the fiber layers. In addition, the wood-like mullite fiber-based porous ceramics also exhibited excellent thermal insulation performance along the X direction due to existence of a large number of pores in the fiber layers. This study provides a new strategy for the preparation of a high-strength thermal insulating fiber-based porous ceramic.