Effect of polysilazane on microstructure and properties of Al2O3-based ceramic core for 3D printing

The performance of an aero-engine is closely related to the cooling ability of the hollow turbine blades. Ceramic core is an important component in the production of hollow turbine blades with a complex structure. As the pace of updating and iteration in turbine blade design continues to accelerate, the internal cavity structures of turbine blades have become increasingly complex. Traditional hot injection process is difficult to meet the production requirements of ceramic cores with complex structures. 3D printing technology can manufacture ceramic cores without the need for moulds, significantly shortening the production cycle and providing a new technology for the production of ceramic cores with complex structures. To meet the technical requirements of the investment casting process, ceramic cores must possess adequate mechanical strength and appropriate porosity. In this work, the ceramic slurry with polysilazane (PSZ) precursor was successfully prepared, and the Al2O3-based ceramic cores with high performance were fabricated using 3D printing technology. The regulation mechanism of polysilazane on the performance of ceramic cores was investigated. The results show that with the increase of PSZ content, the flexural strength of ceramic cores firstly increases and then decreases. When the content of PSZ is 5%, the flexural strength at 25 °C and 1,500 °C are 31.5 MPa and 13.1 MPa, respectively, and the porosity is 36.7%. This work is expected to advance the research and practical application of high-performance ceramic cores fabricated via 3D printing.