关键词: 多孔陶瓷, 莫来石纤维, 3D打印, 隔热材料

Abstract: The traditional molding technology cannot meet the needs of high precision and complex structured mullite fiber based porous ceramics.Photocuring 3D printing technology can directly prepare ceramic materials with nearly net size,which is an ideal technology for preparing complex structured ceramics.The mullite fiber based porous ceramics were fabricated using mullite fibers (substrate) and nano SiO₂ powder (high temperature binder) as main raw materials via photocuring 3D printing technology.The effects of the SiO₂ addition (0,20%,27%,33%,and 38%,by mass) on the dispersion stability,rheological properties and photosensitive properties of the fiber slurries,and the microstructure and physical properties of the mullite fiber based ceramics were investigated.The results show that the introduction of nano SiO₂ significantly increases the viscosity of the slurry,which helps alleviate the fiber sedimentation and agglomeration,thus obtaining a uniform slurry;however,excessive SiO₂ leads to over-high slurry viscosity,which is unfavorable to the 3D printing;when the SiO₂ addition is 33%,the performance of the fiber slurry is suitable for 3D printing,with a settling rate less than 9.7% (within 1 h) and a viscosity of 3.95 Pa·s (shear rate of 30 s^-1);the corresponding mullite fiber based porous ceramics printed using the above slurry exhibit the best physical properties with the bulk density of 0.56 g·cm^-3,apparent porosity of 72%,and thermal conductivity at room temperature of 0.135 W·m^-1·K^-1.

Key words: porous ceramics, mullite fiber, 3D printing, thermal insulation materials