Effect of Aluminum Substrate Surface Modification on Wettability and Freezing Delay of Water Droplet at Subzero Temperatures

Maral Rahimi, Alireza Afshari, Esben Thormann

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

In this study, we have investigated the freezing delay of a water droplet on precooled substrates of an aluminum alloy that is commonly used for heat-exchanger fins. The surfaces of the substrates were modified to obtain surfaces with different hydrophilicity/hydrophobicity and different surface chemistry but without significantly modifying the surface topography. The freezing delays and water contact angles were measured as a function of the substrate temperature and the results were compared to the predictions of the heterogeneous ice nucleation theory. Although the trends for each sample followed the trend in this theory, the differences in the extents of freezing delays were in apparent disagreement with the predictions. Concretely, a slightly hydrophilic substrate modified by (3-aminopropyl) triethoxysilane (APTES) showed longer freezing delays than both more hydrophilic and more hydrophobic substrates. We suggest that this is because this particular surface chemistry prevents ice formation at the interface of the substrate, prior to the deposition of the water droplet. On the basis of our results, we suggest that not only wettability and topography but also the concrete surface chemistry plays a significant role in the kinetics of the ice formation process when a water droplet is placed on a precooled substrate.
Original languageEnglish
JournalA C S Applied Materials and Interfaces
Volume8
Issue number17
Pages (from-to)11147-11153
Number of pages7
ISSN1944-8244
DOIs
Publication statusPublished - 2016

Keywords

  • Aluminum
  • Surface modification
  • Wettability
  • Freezing delay
  • Ice nucleation
  • Surface chemistry

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