In-situ Y₃Al₅O₁₂ enhances comprehensive properties of alumina-based ceramic cores by vat photopolymerization 3D printing

Ceramic cores are an essential part to produce aeroengine turbine blades by investment casting. In recent years, vat photopolymerization (VPP) 3D printing has emerged as a promising technique for fabricating ceramic cores with complex structures due to its advantages of being moldless, low cost, etc. However, how to improve the properties of VPP 3D printed ceramic cores has always been a key bottleneck in industry. In this study, in-situ Y₃Al₅O₁₂ (YAG) enhanced alumina-based ceramic cores with excellent comprehensive properties were fabricated by VPP 3D printing. Alumina-based ceramic core with in-situ generated YAG phase during the sintering process could reduce the high-temperature deflection to almost one-tenth of a pure alumina ceramic core without decreasing the apparent porosity. Furthermore, the lattice characteristics of the YAG phase and Y³⁺ segregation were clarified as the main factors in the improvement of the high-temperature deflection resistance and apparent porosity of ceramic cores. The microstructure demonstrated that the increase of fine powders could narrow down the interlayer gap, and the irregular arrangement of ceramic particles could result in the diversification of sintering grain morphologies. With optimal process parameters, the sintering shrinkage of VPP 3D printed alumina-based ceramic cores in X, Y, and Z directions were 3.8 %, 3.7 %, and 4.8 %, respectively. The apparent porosity, flexural strength, and high-temperature deflection were 40.8 %, 16.1 MPa, and 0.63 mm, respectively. This study has reached an excellent balance between high apparent porosity and low high-temperature deflection of ceramic cores, which provides an important reference for the industrialization of 3D printed ceramic cores.