Additive manufacturing of low-shrinkage alumina cores for single-crystal nickel-based superalloy turbine blade casting

We prepare bimodal particle size photo-curable ceramic pastes with high solid loadings (up to 65 vol %) and fabricate porous alumina ceramic cores with complex shapes via ceramic stereolithography (Cer-SLA) 3D printing technique. The sintering temperature is carefully selected, ranging from 1500 °C to 1650 °C, and a high holding time (>4 h) is applied to guarantee that the materials can withstand the subsequent high temperature (>1500 °C) casting process for single-crystal nickel-based superalloy hollow turbine blades. Herein, the originally spherical fine particles are found to become platelet-like after sintering, and the forming mechanism is discussed in detail. In addition, we explore the influence of platelet-like particles, coarse particles and sintering process on the microstructural evolution of alumina particles, and reveal the relationship between microstructure and properties of ceramic cores. These results illustrate that the proposed materials for SLA 3D printing exhibit a great potential in the fabrication of complex-shaped alumina ceramic cores for high-precision investment casting, e.g., manufacturing single-crystal nickel-based superalloy hollow turbine blades for an advanced aircraft engine.