Session: 17-01-01: Research Posters

Paper Number: 150946

150946 - Adhesion of Impure Ice on Surfaces 

While layers of snow and icicles hanging from trees can make for a picturesque view, undesirable ice accretions on roads, ships, and airplanes can cause a plethora of issues. From diminished tire traction for cars, to decreased fuel efficiency for ships in cold waters, to potentially dangerous rime ice buildup causing mid-flight stalling; finding ways to shed ice from surfaces remains a hotly researched topic across a myriad of occupations. What remains most alluring, yet arguably most difficult to obtain, are cost-effective passive ice-shedding surfaces. While great leaps and bounds have been made in developing these surfaces, such research often assumes pure water freezing on top of rapidly supercooled substrates. However, water found in nature usually contains some dissolved contaminants such as salts, surfactants, and solvents. Studies of ice adhesion using water with known impurity concentrations remain sparce. Furthermore, these contaminants may alter the effectiveness and appropriate conditions of novel passive ice-shedding surfaces. Our work provides useful insights into the elementary nature of impure water-to-ice transformation and contributes to the knowledge base of various natural phenomena and rational design of a broad spectrum of anti-icing technologies for transportation, infrastructure, and energy systems.

We performed a comprehensive battery of experiments that measured the peak shear ice adhesion strength (IAS) and the failure modes of impure ice on three different substrates (glass, copper, and silicon) using aqueous solutions of three separate contaminants (sodium chloride, Triton X-100, and ethanol); with contaminant concentrations ranging from pure water to 1wt%. Next, to gauge whether substrate temperature can be a significant factor in IAS, saline ice from 0.01-1wt% NaCl were tested on mirror-polished copper for supercooling levels of -10C, -20C, and -30C. Once we witnessed a solute enriched liquid layer (SELL) remaining in supercooling levels between 0C and -10C that resulted in sliding of ice, we investigated how contaminates were being initially rejected from the substrate and then being reintroduced back to the surface. For this, we used micro-CT tomography to characterize the brine channels forming in the ice that would lead to solutes draining from the bulk of the ice to the substrate. Lastly, we used MD simulations to model the overall structure and migration/rejection of contaminant molecules as the ice forms.

We have found that a mere 1 wt% of impurities can reduce ice-adhesion strength on conventional hydrophilic surfaces to less than 1 kPa. We show how changes in freezing temperature and contaminant concentration can significantly impact ice adhesion strength, leading to either super-slippery or fiercely adherent surfaces. By using micro-CT tomography, we show how the freezing process affects the microstructure of brine ice that could be responsible for the formation of an in-situ formed solute enriched liquid layer via high-concentration brine channels. Using MD simulations, we show how the disordered ice structure in the vicinity of a solid is affected by the presence of salt and the ice temperature. Finally, for the first time, we also provide visual evidence of impurity rejection/entrapment within a freezing dyed droplet based on controlling the freezing rate of water to rationalize the high adhesion strength of ice on surfaces despite it being formed from impure water. Our findings offer new avenues for studying how impure ice adheres to surfaces, which has direct implications for quantifying ice repellency, understanding glacier movements, and developing freeze-protection technologies for industrial applications.

Presenting Author: Christopher Carducci University Illinois Chicago

Presenting Author Biography: Christopher Carducci is a graduate research assistant for Anand Research Group at the University of Illinois Chicago. He specializes in contaminant separation via controlled freezing. His chief focus is the migration, agglomeration, and entrapment of dissolved species, such as organic and inorganic salts, in freezing water. By combining advanced optical techniques such as confocal laser microscopy, white-light interferometry, micro-CT tomography, and shortwave infrared imaging, his team seeks to find novel viewpoints of how controlled ice growth can effectively reject pollutants from water.

Aside from his research, he manages and mentors small teams of undergraduate engineering students in performing a variety of projects ranging from droplet impacts on omni-phobic surfaces, using CLSM and interferometry to image ice formation and surface interactions, and experimentally simulating impacting freezing sea spray.

Authors:

Christopher Carducci University Illinois Chicago
Rukmava Chatterjee Carrier Corporation
Rajith Unnikrishnan Thanjukutty Abbott Molecular Inc.
Arnab Neogi University Illinois Chicago
Suman Chakraborty Argonne National Laboratory
Vijay Prithiv Bathey Ramesh Bapu Ansys Inc.
Suvo Banik University Illinois Chicago
Subramanian K. R. S. Sankaranarayanan University Illinois Chicago
Sushant Anand University Illinois Chicago