Superwicking Functionality of Femtosecond Laser Textured Aluminum at High Temperatures

Abstract

An advanced superwicking aluminum material based on a microgroove surface structure textured with both laser-induced periodic surface structures and fine microholes was produced by direct femtosecond laser nano/microstructuring technology. The created material demonstrates excellent wicking performance in a temperature range of 23 to 120 °C. The experiments on wicking dynamics show a record-high velocity of water spreading that achieves about 450 mm/s at 23 °C and 320 mm/s at 120 °C when the spreading water undergoes intensive boiling. The lifetime of classic Washburn capillary flow dynamics shortens as the temperature increases up to 80 °C. The effects of evaporation and boiling on water spreading become significant above 80 °C, resulting in vanishing of Washburn’s dynamics. Both the inertial and visco-inertial flow regimes are insignificantly affected by evaporation at temperatures below the boiling point of water. The boiling effect on the inertial regime is small at 120 °C; however, its effect on the visco-inertial regime is essential. The created material with effective wicking performance under water boiling conditions can find applications in Maisotsenko cycle (M-cycle) high-temperature heat/mass exchangers for enhancing power generation efficiency that is an important factor in reducing CO2 emissions and mitigation of the global climate change.

Evaporative and Wicking Functionalities at Hot Airflows of Laser Nano-/Microstructured Ti-6Al-4V Material

“…The surface of the ridges, valleys, and microgroove walls are extensively textured with random fine microholes and microprotrusions in a wide variety of geometrical shapes and dimensions in a range of about 2–13 µm ( Figure 3 c–e). The formation of microholes is the result of the keyhole effect that usually occurs in multipulse femtosecond laser ablation at moderate and high laser fluences [ 41 ]. The surface texture of the microgrooves also includes areas of laser-induced periodic surface structures (LIPSS).…”

“…The wicking dynamics of a liquid in a capillary medium undergo several capillary flow regimes described by a general scaling law h ∝ t n , where h is the spreading distance of the liquid, t is the time, and 2 ≥ n ≥ 0.1 [ 47 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ]. The most studied regime is the classical Washburn capillary flow given by the h ∝ t 1/2 scaling law [ 41 , 42 , 54 , 55 , 59 , 60 ], which is observed in an extremely large variety of capillary media and considered to be a universal law of capillary flow. The Washburn h ∝ t 1/2 dynamics relates to a steady liquid flow when the capillary force is balanced by a viscous force and the effect of gravity is negligible.…”

“…To fabricate the hierarchical surface nano-/microstructures, we used a femtosecond laser nano-/microstructuring method that has been demonstrated to be a powerful tool in fabricating a large variety of hierarchical nano-/microstructures [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. We used this method because several unique monofunctional superwicking materials have been produced previously using femtosecond laser processing, demonstrating the great potential of this method [ 41 , 42 , 43 , 44 , 45 ]. The hierarchical surface nano-/microstructure developed in our work is an array of nanostructured microgrooves fabricated on the surface of a Ti-6Al-4V alloy substrate.…”

Rapid Fabrication of Smooth Micro-Optical Components on Glass by Etching-Assisted Femtosecond Laser Modification

“…To enhance the stability and broaden the optical transmission region, it is necessary to fabricate micro-optical components on hard materials. When fs-laser ablation is used to process hard materials, laser-induced micro/nanostructures and scattered particles are formed on the surface, which has a serious impact on the performance of the micro-optical components [26][27][28][29]. Although laser polishing has been proposed to improve the surface quality [30,31], it does not satisfy the high requirement for applications in optical devices.…”

Special Issue “Dynamics and Processes at Laser-Irradiated Surfaces—A Themed Issue in Honor of the 70th Birthday of Professor Jürgen Reif”

“…Our Special Issue attracted high-quality contributions from both academics and from industry and finally bundles together 1 review paper of Jürgen Reif [ 3 ], 1 perspective article [ 4 ], and 17 original research articles [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. These publications are focusing on the latest achievements in areas of laser–matter interaction [ 16 , 18 , 22 , 23 , 27 , 30 , 31 ], nonlinear optics and photonics [ 22 , 23 , 26 ], spatial beam shaping [ 15 , 28 ], surface dynamics [ 4 , 17 , 22 , 23 ], micro- and nanotechnology [ 16 , 18 , 20 , 24 , 26 , 27 , 31 ], laser-induced periodic surface structures (LIPSS) [ 3 , 4 , 19 , 20 , 21 , 27 ,…”