Effect of sintering temperature on microstructure and properties of 3D printing polysilazane reinforced Al2O3 core

Ceramic cores are the key intermediate components of hollow blades for aero-engine. Conventional processes, such as hot-press molding and gel film casting, face difficulties in fabricating complex-structured ceramic cores due to the complexity of moulds and long process cycles. Stereolithography 3D printing provides a new idea for the fabrication of complex-structured ceramic cores. The effect of sintering temperature on open porosity, bulk density, weight loss rate, shrinkage rate, flexural strength and microstructure of the Al2O3-based ceramic core doped with 10vol.% polysilazane (PSZ) was studied. The sintering mechanism of PSZ-reinforced ceramic cores was analyzed. Results show that the optimum sintering temperature of PSZ-reinforced ceramic cores is 1,450 °C. At this temperature, the open porosity of the ceramic core is 36.60%, bulk density is 2.33 g·cm−3, weight loss rate is 22.11%, shrinkage rate along the X, Y, Z directions is 5.72%, 5.01%, 9.61%, respectively; the flexural strength is 28.794 MPa at 25 °C and 13.649 MPa at 1,500 °C. Properties of 3D printing PSZ-reinforced ceramic cores can meet the casting requirement of superalloy hollow blades, which is expected to promote the industrial application of 3D printing complex structure ceramic cores.