Hydrothermal-assisted jet fusion: a binder-free additive manufacturing approach for ceramics

Additive manufacturing (AM) technologies have proven to be a powerful tool to create ceramics with complex geometries, which are difficult to achieve using traditional machining processes due to their brittleness. For existing AM processes of ceramics, the use of organic binders leads to problems of structural defects, accumulated stress and compromised material properties in the final parts. In this work, a new AM method for ceramics called Hydrothermal-assisted jet fusion (HJF) is proposed, which is capable of fabricating ceramic 3D structures without the need for organic binders. The HJF process selectively deposits a water-based solution into a ceramic powder bed in a layer-by-layer manner and fuses particles together through a hydrothermal mechanism. Since no organic binder is used, it can produce ceramic parts with less energy consumed for binder removal and has the potential to reach the material's theoretical properties such as full density and exceptional mechanical strength. To improve the printing fidelity of HJF process, droplet diffusion behavior in the powder bed under the influence of powder bed’s packing density and compaction pressure was simulated and verified by experiments. Meanwhile, microstructure and physical properties of the printing parts in HJF process were studied under the effect of process parameters such as compaction pressure, ink concentration, etc. Besides, interparticle mass transfer in HJF process was also simulated to understand the fusion mechanism. Finally, HJF process was utilized in the application of antennas, which proves its capability for the direct integration of ceramics with dissimilar materials such as metals and polymers.