Researchers develop scalable surface nanostructuring strategy for metal additive manufacturing

An international research team led by MechSE Professor Nenad Miljkovic has developed an ultra-scalable strategy to generate nanostructures on the aluminum alloy AlSi₁₀Mg. In metal additive manufacturing (AM), which enables “unparalleled design freedom for the development of optimized devices in a plethora of applications,” AlSi¹⁰Mg is one of the most attractive alloys, the team said.  

The project represents a strong ongoing collaboration between UIUC and Singapore’s Nanyang Technological University (NTU), with lead authors Jin Yao Ho, currently an assistant professor at NTU, and recent MechSE graduate Kazi Fazle Rabbi. The team, whose research was carried out in Miljkovic’s Energy Transport Research Laboratory (ERTL), also includes MechSE PhD student Siavash Khodakarami, Associate Professors Teck Neng Wong and Kai Choong Leong from the School of Mechanical and Aerospace Engineering at NTU, and MechSE Professor Bill King, who was recently elected to the 2022 class of SME Fellows for his longstanding contributions to manufacturing engineering.

“Additive manufacturing is known for its flexibility in manufacturing components with highly complex macro-geometries that are not possible through conventional manufacturing techniques,” Ho, first author, said. “Our work demonstrates that the synergistic combination of optimal nanostructuring methods with the wide AM design freedom can be utilized to develop ultra-compact heat exchangers that have excellent thermal performance and power density.”

The team’s surface structuring technique, which is also the featured front piece in Advanced Science, allows for the formation of unique three-dimensional, two-tier nanoscale architectures that enable superhydrophobicity, low droplet adhesion, resistance to condensation flooding, and enhanced liquid-vapor phase transition. The researchers demonstrated that this technique can achieve a 600% improvement in condensation heat transfer coefficient even at elevated vapor pressures and cooling temperatures.

“Considering the growing importance of metal AM processes, the results demonstrated in this project address the existing need to develop rational nanostructuring strategies,” Miljkovic said. “This work demonstrates that a synergistic combination of surface structuring with the complex and co-optimized methodology of AM will not only benefit the energy sector by enabling enhanced two-phase heat and mass transfer, but will also have profound impact on the aerospace, transportation, biomedical, and construction industries, where surface superhydrophobicity, superhydrophilicity, and oleophobicity can play important roles.”

The team’s future work will explore the development of similar design guidelines for alternate AM materials such as copper, titanium, and cobalt alloys as well as stainless steel.

“The development of these alternate materials is motivated by the inability to use AlSi₁₀Mg materials for selected applications such as ultra-high heat flux electronics cooling, which requires higher thermal conductivity alloys such as the copper alloy CuCr1Zr, or seawater condensers that require excellent corrosion resistance facilitated by allows such as 316L stainless steel,” Rabbi said.