Fig. 1. (A) Different perspectives of double wall ceramic core; (B) Scheme of a SLA-3D printed ceramic core emerging from the printer; (C) Slicing layer of double wall ceramic core; (D) Scheme inset of the slip boundary flow profile under the part, with a representative experimentally observed flow profile; (E) Photopolymerization process: degree of conversion versus exposure; (F) Comparison of the developed ceramic core suspension and publicly reported suspensions.

Fig. 2. (A) Microstructures and the particle size distributions of fused silica powders and zirconia powders; (B) 60 vol.% high solid loading ceramic core suspension; (C) Flow and viscosity curves as a function of the shear rate of the ceramic core suspension (The shear rate changes from 130 s?1 to 0.5 s?1); (D) FTIR spectrum of the ceramic core suspension; (E) UV absorption of the 60 vol.% high solid loading ceramic core suspensions in the mode of reflection; (F) The effect of light intensity to curing depth and size of wrong curing zone to select the optimal SLA-3DP parameters; (G) The performance data of high-throughput SLA-3DP ceramic core samples are systematically analyzed to guide the development and application of double wall ceramic core for preparation of single crystal hollow aeroengine blades.

Fig. 3. (A) TG-DTA curves for SLA-3DP 60 vol.% high solid loading ceramic core green body samples; (B) Profiles of debinding and sintering processes; (C) Room-temperature XRD patterns of SLA-3DP ceramic core samples sintered at different temperatures; (D) Room-temperature XRD patterns of SLA-3DP ceramic core samples sintered at 1100 °C, 1150 °C, 1200 °C, and 1250 °C after flexural strength test at 1550 °C; (E) 25 °C room-temperature and 1550 °C high-temperature flexural strengths of SLA-3DP ceramic core samples sintered at 1100 °C, 1150 °C, 1200 °C, and 1250 °C; (F) Shrinkage as a function of sintering temperature 1100 °C, 1150 °C, 1200 °C, and 1250 °C; (G) Bulk densities as a function of sintering temperature 1100 °C, 1150 °C, 1200 °C, and 1250 °C; (H) Open porosity rates of SLA-3DP ceramic core samples sintered at 1100 °C, 1150 °C, 1200 °C, and 1250 °C; (I) Number of cracks of SLA-3DP ceramic core samples sintered at 1100 °C, 1150 °C, 1200 °C, and 1250 °C different temperatures.

Fig. 4. SEM images at different spatial locations for typical microstructures characteristics such as large grains, cracks, pores and crack prapagation of SLA-3DP ceramic core samples sintered at different temperatures: 1100 °C, 1150 °C, 1200 °C, and 1250 °C. (A) Surface microstructures; (B) fracture microstructures after flexural strength test at room-temperature; (C) Surface microstructures of different magnification after flexural strength test at 1550 °C; (D) Fracture surface of different magnification after flexural strength test at 1550 °C.

Fig. 5. (A) Radar charts of some representative properties and crucial process parameters: room temperature bending strength (MPa), bulk density (g cm?3), shrinkage (%), porosity (%), and sintering temperature (°C) of SLA-3DP ceramic core samples sintered at different temperatures, showing the balance of multiple properties and process parameters optimization achieved for application; (B) Ashby chart for number of cracks, room temperature bending strength, high temperature bending strength, shrinkage, and porosity at different sintering temperatures. The performance data and process parameters of SLA-3DP ceramic core obtained in this work could predict and guide the selection of the most effective process parameters; (C) Key challenges associated with the stereolithography-based three-dimensional printing of ceramic cores applied for preparation of single crystal hollow aeroengine blades.