Nanotextured Aluminum-Based Surfaces with Icephobic Properties

Abstract

Undesirable water freezing (icing) usually occurs in cold environments and may have lethal consequences. Preventing icing usually requires the installation of active thermal systems which consume energy and increase costs. Nanoengineered superhydrophobic surfaces can delay freezing passively; however, when exposed to sub-zero temperatures, they can get covered by frost, which promotes ice formation and impairs their icephobicity. In addition, high thermal conductivity of the surfaces can reduce the frost formation rate. Thus, we chose aluminum as our working material for its good thermal conductivity and widespread industrial usage. We employed electrochemical anodization process to control and tune the surface morphology. Crucially, we demonstrate the feasibility of morphology control at the nanoscale and tunability of the surface solid fraction in the range of 0.1–0.25, while using safer polishing electrolytes and etchants compared to existing practice, i.e., our approach is environmentally friendlier. Surface functionalization and morphology control were used to render the surfaces (super) hydrophobic, with low contact angle hysteresis. The best performing surfaces demonstrate ice nucleation temperatures as low as –19 °C and resist liquid impalement—tested via drop impact velocity up to 3 m/s (Weber number > 300)—demonstrating a clear potential for their exploitation as icephobic surfaces.

Notes on contributors

Michael Grizen is investigating interfacial phenomena and phase change processes. Beforehand, Michael worked for 4 years as a thermal engineer in the space industry. He received his Bachelor (summa cum laude) and M.Sc. (direct track) from Tel-Aviv University. During his M.Sc. studies, he carried out research in the field of solar radiation harvesting. His PhD project involves experimental investigation of ice nucleation and impact of cold droplets on nanoengineered surfaces. Through a better understanding of the nucleation process combined with rationally manufactured surfaces, he hopes to efficiently suppress ice and frost formation.

Tanmoy Maitra is a Materials Scientist (Specialist) at FT Technologies UK. His current work focuses on the evaluation and implement materials and solutions to improve the performance of high-performance acoustic resonance wind sensors. He obtained his PhD from ETH Zurich, Switzerland. After graduating, he joined as a Postdoctoral Fellow at Stanford University with a Swiss National Science Foundation (SNSF) Fellowship. After that, he moved to University College London (UCL) as a Research Associate to work on multifunctional superhydrophobic materials, icephobicity and additive manufacturing. He has published papers in high-quality journals and presented in several international conferences in the area of thermal-fluid sciences. He represented UCL to the prestigious Global Young Scientist Summit (GYSS) in Singapore in 2018. He was also awarded ETH medal (2016) for his doctoral thesis, Ambuja’s Young Researcher Award (2012) for one of the best master’s thesis in India, and Academic Excellence Award (2009–2010) in Indian Institute of Technology, Kanpur.

Jeremy P. Bradley studied Materials Science and Technology at Brunel University graduating in 1997. He then worked for the Defense Evaluation Research Agency (DERA) in Farnborough as a research scientist. After a short period as a Technical Salesperson for Olympus Optical UK, he joined Airbus as a materials specialist. Currently he is the Head of Corrosion prevention principles and sealing for all aircraft. During his time at Airbus he has been heavily involved in materials research including new sealant chemistries, novel sealing methods and functional coatings for aerodynamic performance, anti-ice and self-cleaning properties.

Manish K. Tiwari is a Professor of Nanoengineering in the Mechanical Engineering Department of the University College London and directs the Nanoengineered Systems Laboratory. His group focuses on the physics of small-scale transport phenomena and nanomanufacturing technologies, to underpin new developments in energy and healthcare applications. He has published papers in high-quality journals such as Nature Materials, Nature Communications, PNAS, Nano Letters etc. He is an European Research Council (ERC) Starting Grant Awardee and a member of the EPSRC Early Career Forum in Manufacturing Research.

Additional information

Funding

The work was partially supported by M.K.T.’s EPSRC First Grant (EP/N006577/1) and from the European Research Council (ERC) under the European Uninon’s Horizon 2020 research and innovation program under grant agreement no. 714712.