Balancing flexural strength and porosity in DLP-3D printing Al₂O₃ cores for hollow turbine blades

High porosity and high strength are usually mutually exclusive in the preparation of ceramic materials. However, high porosity and flexural strength are required for the preparation of complex ceramic cores for hollow turbine blades. In this study, Al₂O₃ cores with high porosity and high flexural strength were successfully prepared using digital light processing (DLP) 3D printing technology. The influence of sintering temperature on the microstructure, pore evolution, and flexural strength of the cores were investigated. With an increase in the sintering temperature, the porosity of the ceramic cores first increased and then decreased, reaching a maximum value of 35% at 1400 °C. The flexural strength increased with the increase in sintering temperature, but at 1400°C the incremental enhancement of flexural strength was greatest. Combined with the core service requirements and core performance, this study selected 1400 °C (open porosity of 35.1% and flexural strength of 20.3 MPa) as the optimal sintering temperature for the DLP-3D printed Al₂O₃ core.