Controlling the cristobalite content, microstructure, and properties of vat photopolymerization 3D printed SiO2-based ceramic cores by doping Fe2O3

The casting of aero-engine turbine blades relies on the use of ceramic cores, which serve as integral components in the manufacturing process. The utilization of vat photopolymerization 3D printing without the necessity for a mold facilitates the fabrication of intricate double-walled ceramic cores. Fused silica (SiO2) is a material that is widely used in the preparation of ceramic cores due to a number of favorable properties, including excellent thermal expansion, thermal shock resistance, and ease of leaching in alkali solution. However, the crystallization behavior of fused silica (fused silica -> cristobalite) has the potential to result in a reduction in the mechanical properties of the resulting ceramics. In this study, SiO2-based ceramics with varying Fe2O3 contents were fabricated via vat photopolymerization 3D printing technique. The effect of Fe2O3 on the cristobalite crystallization, microstructure, and properties of the ceramic cores was investigated. The results demonstrate that a modest Fe2O3 content affects the cristobalite content by affecting the ratio of bridge oxygen to non-bridge oxygen in the ceramic cores. The addition of 0.2 wt% Fe2O3 resulted in a reduction in the cristobalite content, from 36.2 % to 28.2 %. Consequently, the mechanical properties were enhanced. The flexural strength at room temperature (25 degrees C) was increased from 11.32 MPa to 14.31 MPa, and the flexural strength at high temperature (1500 degrees C) was increased from 17.78 MPa to 20.73 MPa, meeting the required specifications for turbine blade casting. The findings of this study offer novel insights into the control of cristobalite content in vat photopolymerization 3D printed SiO2-based ceramic cores and provide a promising avenue for the development of SiO2-based ceramic cores with enhanced mechanical properties.