LPBF Fabrication of 17-4 PH Stainless Steel TPMS Structures and Wettability of Surface-Treated Flat Plates

This study investigates the laser powder bed fusion (LPBF) fabrication of 17-4 PH stainless steel triply periodic minimal surface (TPMS) structures and the wettability response of corresponding flat plates subjected to selected post-processing treatments. Five TPMS geometries were fabricated and visually examined to document their overall condition and manufacturing irregularities. Thermal aging, steel shot blasting, commercial hydrophobic coating, and selected treatment combinations were evaluated on flat plates manufactured using the same material and LPBF process. Wettability was assessed using time-dependent static contact angle (CA) measurements and a preliminary comparison of three steel shot grades. The fabricated TPMS structures retained their overall geometries but exhibited localized burnt edges, distortion of thin boundary features, and differences in surface appearance. The untreated LPBF-fabricated surface was hydrophilic and exhibited time-dependent wetting, with the CA decreasing from approximately 81° to as low as 48° within 4 min and complete wetting occurring within approximately 8–10 min. Among the evaluated blasting media, S-330 produced the highest CA values; however, blasted surfaces remained hydrophilic, and the response depended on whether the plate was untreated or aged. The coating produced CA of approximately 153–170° across all coated regions, both with and without prior blasting. These findings identify manufacturing considerations for LPBF-fabricated TPMS structures and demonstrate the effects of the investigated treatments on the wettability of corresponding flat surfaces, thereby providing insights for future studies of TPMS-based condensation surfaces in atmospheric water generation applications.