High-resolution porous media and enhanced capillary performance prepared by micro laser powder bed fusion

The feature designability, customization, and capacity to produce arbitrary complex structures make laser powder bed fusion (PBF-LB/M) a promising candidate for manufacturing of porous media. However, the limited manufacturing resolution (> 100 µm) of PBF-LB/M results in a geometry and performance gap between the designed and manufactured porous structure. In this work, a high-resolution micro PBF-LB/M method utilizing a laser beam of 25 µm and powder particle diameter of 2–15 µm was employed to fabricate the 316 L stainless steel porous wicks. A melt-pool resolution of ∼60 µm was achieved, which is higher than other previously reported PBF-LB/M wicks. This high manufacturing resolution effectively reduced the average error between the designed and actual porosity to < 2.6%. Rate of Rise experiments showed that the 80%-porosity structure achieved an optimum hydraulic performance ( K / r e f f ) of 1.49, which is 2.3 times higher than previously reported in the literature for cross-hatched porous structures with comparable porosity and still higher than known strut-based lattice wicks. Comparison between experiments and simulation suggested that reducing the melt dross and attached powders can further improve the capillary performance. This work elevates porous wick manufacturing to a higher resolution level and paves the way for preparing high-performance porous wicks.