Capillary performance of strut-based lattice wicks fabricated using laser powder bed fusion

Laser powder bed fusion (LPBF) can be used to fabricate porous wicks with customized geometries for two-phase heat transport devices such as heat pipes; LPBF enables integration of these wicks into any two-phase transport device form factor in a single manufacturing step. Strut-based wicks with four different unit-cell geometries (simple cubic, body-centered cubic, face-centered cubic, and fluorite) with different porosities were designed and fabricated using LPBF. The capillary performance of the wicks was characterized using the mass rate-of-rise (m-t) method and quantified in terms of the ratio of permeability to effective pore radius ( K/r eff ). Both unit-cell geometry and porosity significantly affect the capillarity of these strut-based wicks, with K/r eff ranging from 0.05 to 1.43 μm, which is commensurate with conventional sintered metal wicks. This is due to a relatively high permeability, ranging from 39 μm 2 to 788 μm 2 , and an effective pore radius ranging from 233 μm to 1022 μm. The simple cubic 52 % and 65.1 % porous wicks exhibited the highest capillary performance with a K/r eff of 1.43 μm and 1.31 μm, respectively. These results suggest that modifying the LPBF process for finer feature resolution could result in higher capillarity.