Tunable and Robust Nanostructuring for Multifunctional Metal Additively Manufactured Interfaces

Abstract

Novel processing phenomena coupled with various alloying materials used in metal additive manufacturing (AM) have opened opportunities for the development of previously unexplored micro-/nanostructures. A rationally devised structure nanofabrication strategy of AM surfaces that can tailor the interface morphology and chemistry has the potential for many applications. Here, through an understanding of grain formation mechanisms during AM, we develop a facile method for tuning micro-/nanostructures of one of the most used AM alloys and rationally optimize the morphology for applications requiring low surface adhesion. We demonstrate that optimized AM structures reduce the adhesion of impaling water droplets and significantly delay icing time. The structure can also be altered and optimized for antiflooding jumping-droplet condensation that exhibits significant enhancement in heat transfer performance in comparison to nanostructures formed on conventional Al alloys. In addition to demonstrating the potential of functionalized AM surfaces, this work also provides guidelines for surface-structuring optimization applicable to other AM metals.

Manipulation of droplets and bubbles for thermal applications

“…As such, scalable manufacturing methods such as chemical etching and oxidation 120 and sandblasting 121 have recently been developed to obtain required surface morphologies. Furthermore, an emerging area of interest is to utilize additive manufacturing to engineer micro‐ and macrostructures for thermal applications 122–125 …”

“…Furthermore, an emerging area of interest is to utilize additive manufacturing to engineer micro-and macrostructures for thermal applications. [122][123][124][125] While useful, static manipulation techniques lack real-time control and tunability which is often desired in practical applications.…”

Advances in micro and nanoengineered surfaces for enhancing boiling and condensation heat transfer: a review

“…Recent studies have focused on synergistic combination of micro and nanostructuring of AM metal surfaces along with its design exibility to further enhance condensation performance. 201,210,266 Due to signicantly different elemental composition of AM materials along with the AM laser melting and rapid solidication processes, as fabricated AM surfaces consist of unique sub-grain structures compared to conventionally manufactured metal surfaces. [267][268][269] Researchers have demonstrated that these unique sub-grains have unveiled the possibility of generating unique micro and nanostructures by varying heat and chemical treatment of AM surfaces.…”

“…16E). 210 These nanostructures i.e., nanocells, nanocell with nanobumps and microsteps can be utilized to develop superhydrophobic surfaces with varying degrees of droplet adhesion and condensate droplet repellency. The study compared the jumping droplet condensation performance of a conventional boehmite nanostructured surface with an AM non-heat treated etched (nanocells) and heat-treated etched (nanocell with nanobumps) AM surface.…”

How Superhydrophobic Grooves Drive Single-Droplet Jumping

“…Removal of droplets from solid surfaces , is relevant to the success of numerous applications, including self-cleaning, , heat-transfer enhancement, − antifrosting, − and water harvesting. − To improve the efficiency of droplet removal, many techniques have been adapted, such as droplet-bouncing manipulation, electrostatic repulsion, − capillarity, , wettability gradients, , Leidenfrost effect, , and surface structuring or topologizing. − …”