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Ice resistant coating for large structures is based on a “beautiful demonstration of mechanics”

Anish Tuteja, associate professor of materials science and technology at the University of Michigan and his research group has created a coating that shoots ice from large surfaces. Credit: Joseph Xu / Michigan Engineering, Communications and Marketing A new class of coatings that throw the ice easily from evenly large surfaces has moved researchers closer to its decades long targets for ice-resistant cargo ships, aircraft, power lines and other large structures. The spray coatings developed at the University of Michigan make the ice fall away from structures, regardless of size &#821 1; with just a slight breeze or often the weight of the ice. A paper on the research is published in Science . In a sample of a mock power line, the coating immediately threw ice. The researchers exceeded a large limitation of previously ice-repellent coatings while they worked well in small areas, researchers found in field testing that they did not throw ice on very large areas as efficiently as they had hoped. It is an issue because ice tends to cause the greatest problems on the largest surfaces, as effectively as possible, compromising safety and requiring costly removal. They cleared this obstacle with a "beautiful demonstration of mechanics". Anish Tuteja, Associate Professor of Materials Science and Technology, described how he and his colleagues turned to a property that is not well known in icing. "For decades, pavement research has focused on lowering the adhesion force per unit required to tear an ice cube from one surface," Tuteja…

Anish Tuteja, associate professor of materials science and technology at the University of Michigan and his research group has created a coating that shoots ice from large surfaces. Credit: Joseph Xu / Michigan Engineering, Communications and Marketing

A new class of coatings that throw the ice easily from evenly large surfaces has moved researchers closer to its decades long targets for ice-resistant cargo ships, aircraft, power lines and other large structures.

The spray coatings developed at the University of Michigan make the ice fall away from structures, regardless of size &#821

1; with just a slight breeze or often the weight of the ice. A paper on the research is published in Science .

In a sample of a mock power line, the coating immediately threw ice.

The researchers exceeded a large limitation of previously ice-repellent coatings while they worked well in small areas, researchers found in field testing that they did not throw ice on very large areas as efficiently as they had hoped. It is an issue because ice tends to cause the greatest problems on the largest surfaces, as effectively as possible, compromising safety and requiring costly removal.

They cleared this obstacle with a “beautiful demonstration of mechanics”. Anish Tuteja, Associate Professor of Materials Science and Technology, described how he and his colleagues turned to a property that is not well known in icing.

“For decades, pavement research has focused on lowering the adhesion force per unit required to tear an ice cube from one surface,” Tuteja said. “The problem with this strategy is that the larger the ice sheet, the more power is required. We found that we encountered the boundaries of low adhesion strength, and our coatings became ineffective when the surface became large enough.”

Professor Anish Tuteja’s group at the University of Michigan demonstrates the performance of a low interface LIT coating in ice scrubbing for various applications and conditions. Credit: Abhishek Dhyani

The new coatings solve the problem by introducing a second strategy: low interface hardness, abbreviated LIT. Surfaces with low interface hardness encourage cracks to form between ice and surface. And, unlike breaking an ice sheet’s surface adhesion, which requires the entire sheet to be free, a crack breaks only the surface free along its leading edge. When the crack begins, it can spread quickly over the entire ice surface, regardless of size.

“Imagine pulling a carpet over a floor,” says Michael Thouless, Janine Johnson Wein Mechanical Engineering Professor. “The larger the carpet, the harder it is to move. You are resistant to the strength of the entire interface between the carpet and the floor. The frictional force is analogous to the interface strength.”

“But now imagine that there is a wrinkle in that carpet. It is easy to continue pushing that wrinkle over the carpet, no matter how large the carpet is. The resistance to the propagation of the wrinkle is analogous to the interface durability which resists the spread of crack. “

Thouless said the concept of interface hardness is well known in crack mechanics, where it supports products such as laminated surfaces and glue-based flight joints, but so far it had not been applied in ice saturation. The advance came when Thouless learned about Tuteja’s previous work and saw an opportunity.

  •  Ice resistant coating for large structures is based on a Anish Tuteja, associate professor of materials science and technology at the University of Michigan and his research group has created a coating that shoots ice from large surfaces. Credit: Joseph Xu / Michigan Engineering, Communications and Marketing
  •  Isisät coating for large structures is based on a Anish Tuteja, associate professor of materials science and technology at the University of Michigan and his research group has created a coating that gives off ice-large surfaces. Credit: Joseph Xu / Michigan Engineering, Communications and Marketing
  •  Ice resistant coating for large constructions is based on a Anish Tuteja, associate professor of material science and technology at the University of Michigan and his research group has created a coating that gives off ice large surfaces. Credit: Joseph Xu / Michigan Engineering, Communications and Marketing

“Traditionally, researchers only care about interface hardness, and ice saturation researchers often care about interface strength,” Thouless said. “But both parameters are important for understanding adhesion.”

“I pointed out to Anish that if he were to test increasing ice lengths he would find that the failure would rise while the interface strength was important, but then plateau once became tough. Important. Anish and his students tried the experiments and ended with a really beautiful demonstration of the mechanics, and a new concept for stapling. “

To test the idea, Tuteja’s law used a technique he honed during previous pavement research. Out of the properties of a large library of substances and adding interfaciality and adhesion strength to the equation, they could mathematically predict the properties of a coating without having to physically test each one. This allowed them to gather a large variety of combinations, each with a tailor-made interface between adherence and adhesion strength.

They tested a variety of surface coatings on large surfaces – a stiff aluminum sheet about 3 feet square and a flexible aluminum piece about 1 inch wide and 3 feet long, to mimic a power line. On each surface, the ice fell immediately due to its own weight. However, it adhered to the control surfaces, which were identical in size to one coat and another coated with an earlier isobobic coating.

The team’s next step is to improve the durability of the LIT coatings.


Spray-on coating can be resistant to aircraft, power lines, windshields


More information:
K. Golovin et al., “Low-limit toughness material for efficient large-scale de-icing” Science (2019). science.sciencemag.org/cgi/doi … 1126 / science.aav1266
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Michigan University

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Ice resistant coating for large structures is based on a “beautiful demonstration of mechanics” (2019, April 25)
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