Near-infrared photothermal dual crosslinking strategy for precise and efficient direct ink writing of high solids ceramic slurries

During the ceramic photocuring 3D printing process, the penetration ability of incident light is hindered by the extinction effects of ceramic powders in ceramic slurry. This limitation in light penetration negatively impacts printing efficiency, especially in ceramic slurries with high solid contents. In this work, an in-situ photothermal dual crosslinking strategy, which capitalizes on the combined benefits of near-infrared photothermal energy, was proposed to realize precise and efficient direct ink writing of high solids ceramic slurries. The in-situ curing of ceramic slurries with an alumina content of up to 90 wt% (74.5 vol%) was successfully achieved by integrating photochemical and photothermal crosslinking strategies to recycle excess heat to enhance the energy utilization of near-infrared light. Under near-infrared irradiation (538.25 W/cm2, 3s), the high solids ceramic photothermal dual curing slurry achieved a curing depth of 2.79 mm, which improved the printing rate and printing throughput compared with the photocuring slurry (2.34 mm) and the thermocuring slurry (0.98 mm). The sintered samples showed a sinter shrinkage of 8.85% and relative density of 95.08%. This method has great potential for application in the manufacturing of thick composite materials and high solid content slurry printing.