Tailoring Wicking and Fluid Transport Properties in Laser Powder Bed Fusion Additively Manufactured Aluminum Alloy Lattice Structures for Heat Transfer Systems

Additively manufactured lattices allow the capillary and hydraulic properties of a wick to be set by design, but the combined effect of lattice architecture and chemical post-processing on fluid transport in aluminum alloys is not well established. Twelve AlSi10Mg lattices were fabricated by laser powder bed fusion (LPBF) in body-centered cubic (BCC) and face-centered cubic (FCC) architectures with unit cell sizes of 1.5 and 2.0 mm and strut diameters of 0.30–0.40 mm. Porosity, steady-flow pressure-drop permeability, and capillary rise in methanol were measured before and after a 90 s sodium hydroxide etch; measured pressure gradients were compared with numerical simulations. As-built porosity was 3–12% below the design value because of adhered powder; etching restored it to within about 5%. Permeability normalized by the square of the strut diameter increased exponentially with porosity, and BCC lattices were two to four times more permeable than FCC lattices of the same dimensions. Etching increased the permeability of the FCC lattices by a factor of 1.5–2.1 but reduced the capillary rise height in most specimens by up to 38%. Simulated pressure gradients were within 20% of the measurements for BCC lattices but under-predicted those of FCC lattices by 11–51%. Overall, properly controlled chemical etching reduced the discrepancy between simulated and measured pressure gradients. These findings identify a trade-off between hydraulic permeability and capillary rise within the tested configurations and treatment conditions; device-level thermal performance remains to be evaluated.