Controlling the anisotropy behaviour of 3D printed ceramic cores: From intralayer particle distribution to interlayer pore evolution

The ceramic cores used in advanced aero-engine blades are becoming increasingly complex. Vat photopolymerisation 3D printing core technology has been used to compensate for the limitations of traditional hot-injection processes in the preparation of complex cores. However, 3D printed cores exhibit anisotropy of strength and sintering shrinkage, which requires further research and development. Herein, ceramic core samples were prepared from the X, Y, and Z directions using vat photopolymerisation 3D printing technology, and the anisotropic behaviour was systematically studied. The mechanism of core delamination was studied using a finite element simulation of slurry spreading during the printing process. In the slurry spreading process, the flow rate of the slurry middle layer was faster than that of the upper and lower surfaces, and fine particles concentrated more easily on the upper and lower surfaces. The interface between the layers was composed of fine particles. The interfacial sintering was compact and the pores were small. The interior of the lamellar structure was composed of coarse particle with large and dispersed pores. In addition, the distribution of pores within the 3D printed core presents an evolution law during the sintering process. With an increase in the sintering temperature, the pores move toward the interface between the layers and are enriched, and the pores coalesced to form larger pores at the interface. When sintered at high temperatures, the interfacial pores formed a gradient line between the porous layers. The combination of finite element simulation and experimentation provides theoretical guidance for the control of the layered structure and anisotropy of 3D printed cores. This promotes the application of 3D printed ceramic technology in the industrial field.