Phase change materials (PCM) based cold source for selective freezing 3D printing of porous materials

Selective freezing three-dimensional (3D) printing is a promising manufacturing process, which can fabricate multi-scale and multi-functional porous structures with excellent geometrical and functional integrity. In this process, the fabrication temperature affects both the macroscopic and microscopic structures of the resulting part; therefore, the cold substrate plays an important role in controlling the process reliability and part quality. To improve its thermal stability and efficiency both temporally and spatially, we propose a novel cold source design based on phase change materials (PCM). Aqueous sodium chloride and ammonium chloride with different concentrations and volumes are experimentally studied to verify the effectiveness of the PCM serving as the cold source for the printing process. A holistic thermal enhancement strategy is applied to improve the duration and thermal stability. The feasibility and effectiveness is well validated by the hardware-in-loop experimental study. The results demonstrate that the proposed cold source design can lead to more reliable and stable printing process and consequently promote its wider industrial applications in various areas.