Deicing technologies often rely on heat to melt ice. But University of Texas at Dallas researchers have found that, under extreme cold, making ice even colder can weaken its grip on surfaces.
"Our work shows that under extremely cold conditions, rapid cooling can actually make ice much easier to remove," said Dr. Hongbing Lu , professor of mechanical engineering and the Louis Beecherl Jr. Chair in the Erik Jonsson School of Engineering and Computer Science .
The discovery, published online May 29 in the journal Newton , reveals that a material's thermal properties play a critical role in determining whether ice remains attached to a surface. The finding could guide the design of future deicing systems for aircraft, wind turbines and other applications in extreme cold.
Lu, who directs the Mechanics of Advanced Materials Laboratory , is a co-corresponding author of the study with Dr. Xianming "Simon" Dai, associate professor of engineering technology and industrial distribution at Texas A&M University and a former associate professor of mechanical engineering at UT Dallas.
Ice accumulation on aircraft, wind turbines and power infrastructure can ground flights, reduce energy production and damage equipment. While heating can be an effective method for removing ice, supplying enough heat in very cold environments can be difficult and energy intensive.
In addition to using heat to melt ice, deicing procedures also can involve changing the chemistry of surfaces to prevent ice from sticking. Those methods, however, become less effective in extremely cold conditions, when ice still can form strong bonds with the surface.
Cracks formed in the ice on this metal sample show how rapidly cooling ice can weaken its grip on the surface in extreme-cold conditions.
UT Dallas researchers made their discovery while conducting experiments to develop ice-resistant surfaces for cold environments.
The team cooled ice on metal, glass and plastic surfaces to minus 76 degrees Fahrenheit (minus 60 degrees Celsius) to investigate whether rapid temperature changes could weaken ice adhesion. Many materials, including solid ice, contract as they get colder, but how much they change size depends on the material.
Metal and glass have similar thermal expansion properties, so researchers expected the ice to behave similarly on both surfaces. Instead, the ice released easily from the cooled metal but remained firmly attached to the glass.
At first, the result didn't make sense.
"It puzzled us for a long time," Lu said.
As team members looked for explanations for the unexpected behavior, they determined that the thermal conductivity of the surface played a critical role in whether the ice would detach.
In particular, the way a surface transfers heat determines the temperature change at the ice-surface interface. In general, materials that transfer heat more efficiently can cool the ice more rapidly.
"We determined that the observed behavior is the result of differences in thermal conductivity of the substrate," Lu said. "So, simply put, the ice touching steel gets colder much faster than ice touching glass."
Because the metal conducted heat more efficiently than glass or plastic, the ice on the metal surface cooled and contracted more than on the other surfaces. This created stresses that fractured the ice, reducing its adhesion to nearly zero.
"The ice wants to shrink more than the steel does, but because they are bonded together, the steel holds it back, putting the ice under tensile stress," Lu said.
The study's findings challenge conventional thinking by showing that the speed at which a surface conducts heat is an important factor in determining whether ice will detach.
"On a surface with very high thermal conductivity, we don't want to warm the ice — we may actually want to cool it," Lu said. "The larger temperature drop creates greater stresses in the ice, which, combined with the mismatch in how the materials contract, can cause the ice to fracture."
The researchers developed a model that predicts how different materials will behave during rapid cooling, which could help engineers design future deicing systems.
The researchers also tested composite materials relevant to aircraft and wind turbine blades and found that carbon fiber composites, which have higher thermal conductivity than glass fiber composites, created weaker ice interfaces, making ice easier to detach.
Although additional research will be needed before the approach could be incorporated into practical deicing systems, the findings suggest that in extremely cold environments, making ice colder rather than warmer may be a better approach.
"Conventional wisdom says we need to introduce heat," Lu said. "In some cases, however, the colder the better."
Other UT Dallas-affiliated authors of the article were Jyotirmoy Sarma MS'18, PhD'22; Dylan Boylan PhD'25; and mechanical engineering research associate Dr. Yao Ren; from Texas A&M, postdoctoral researcher Deepak Monga PhD'24 and graduate student Meiying He contributed to the work.
Lu received funding for the research from the U.S. Department of Energy (DOE) (NA0003962, NA0003525) and the National Science Foundation (NSF) ( 2219347 ). Dai received support from the Army Research Office (W911NF1910416), DOE (EE0011217), the Defense Advanced Research Projects Agency (D23AP00160) and the NSF ( 2044348 ).
