Design and formation mechanism of in-situ synthesis YAG sintered necks in stereolithography 3D printed Al2O3-based ceramic cores

The intricate structure of ceramic cores is crucial in producing high-temperature-resistant hollow blades. Traditional techniques for ceramic cores preparation, such as hot injection, rely heavily on moulds, thus limiting the production of complex structures in ceramic cores. Stereolithography 3D printing technology provides a novel approach to creating these cores, leveraging its precision and model customization capabilities. However, issues like the challenge of effectively controlling both porosity and strength hinder its widespread adoption. In this study, high-performance ceramic cores reinforced with in-situ YAG were successfully prepared by adding Y2O3 using stereolithography 3D printing technology. Thorough thermodynamic calculations for Y2O3 incorporation into Al2O3-based ceramic cores were systematically analysed, revealing the formation of Y3Al5O12 (YAG) at elevated temperatures due to Y2O3 and Al2O3 interaction. Subsequently, the variations in microstructure and properties were investigated across different temperatures. Due to diffusion, YAG sintered necks and cohesive framework were formed on the surface of Y2O3, resulting from the reaction between Y2O3 and Al2O3. YAG sintered necks and Y2O3 effectively inhibited crack deflection. The high degree of densification of the in-situ generated YAG and cohesive framework improved the mechanical properties; meanwhile, the presence of porosity between YAG and Al2O3 contributed to the enhancement of porosity. The cores exhibited exceptional mechanical properties at 1823.15 K. The open porosity was 30.08%. The flexural strengths were 41.2 MPa (298.15 K) and 32.0 MPa (1773.15 K). The design of YAG sintered necks by adjusting the sintering temperature introduced a new idea for synergistically adjusting porosity and strength. The advancement is anticipated to improve the production of intricately structured ceramic cores with superior performance.