In-situ sintered mullite whiskers to enhance the thermal shock resistance of binder jetting Al2O3-based ceramics

Binder Jetting is a very advantageous additive manufacturing technology for the fabrication of complex Al2O3 ceramics. However, the powder stacking and bonding characteristics led to relatively poor strength and toughness of Al2O3 ceramics. In this work, we presented a method to improve the thermal shock resistance of Al2O3-based ceramics by in-situ generation of mullite whisker. The effects of SiO2 particle size, SiO2 addition amount, and sintering time on the performance of Al2O3-based ceramics were investigated in detail. The results indicate that the particle size of SiO2 powder is 1.8 mu m with 2 wt% addition amounts, the formation of mullite whiskers on the surface of Al2O3 particles after sintering at 1450 degrees C for 6 h and significantly improves the thermal shock resistance. The residual strength increased from 15.62 MPa to 34.18 MPa, while fracture toughness rose from 1.68 MPa & sdot;m1/2 to 2.44 MPa & sdot;m1/2, indicating a transition from brittle to tough crack propagation.