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

摘要： 传统的成型技术已经无法满足各行业对高精度、复杂结构莫来石纤维基多孔陶瓷的需求,光固化3D打印技术可以直接制得近净尺寸的陶瓷材料,是制备复杂结构陶瓷的理想技术。以莫来石纤维(基体)和纳米SiO₂粉(高温黏结剂)为主要原料,采用光固化3D打印技术成功制备了莫来石纤维基多孔陶瓷。研究了纳米SiO₂粉加入量(加入质量分数分别为0、20%、27%、33%和38%)对纤维浆料的分散稳定性、流变特性和光敏性能的影响,以及对莫来石纤维基多孔陶瓷的显微结构和物理性能的影响。结果表明:SiO₂粉使纤维浆料的黏度显著提升,这有助于缓解纤维的沉降、团聚,获得均匀的打印浆料;但过量的SiO₂粉将导致浆料黏度过大,不利于3D打印过程顺利进行。当SiO₂粉加入量为33%(w)时,纤维浆料的性能最适合3D打印,其在1 h内的沉降率小于9.7%,黏度为3.95 Pa·s(剪切速率为30 s^-1);采用上述浆料打印的莫来石纤维基多孔陶瓷表现出最佳的物理性能(体积密度为0.56 g·cm^-3,显气孔率为72%,室温下的热导率为0.135 W·m^-1·K^-1)。

关键词: 多孔陶瓷, 莫来石纤维, 3D打印, 隔热材料