Every year, frost comes and creates beautiful and serene scenery. This thin layer of ice forms on a solid surface like the ground when the temperature drops to freezing levels or below.
When the air has more water vapor than it is able to contain at a specific temperature, frost forms.
While beautiful, frost is also potentially dangerous. Not only can it be a headache to scrape off slippery surfaces, but it also leads to other serious issues like impaired vehicle sensors, the reduced energy efficiency of refrigerators and freezers, added weight on power lines that can cause outages and damage to your precious vegetable and flower garden.
This isn’t all. Frost also negatively impacts aircraft by stalling speed, diminishing control efficiency, and destabilizing pitch, which can lead to crashes. It further interferes with aircraft take-offs by altering the aerodynamic characteristics of wings, making flights dangerous or even impossible.
While Tony Stark in Iron Man may be able to use the ice buildup on his suit to his advantage and against his opponent, this is simply not possible for us to achieve in our regular lives.
What we need is an effective solution to this hundreds of billion-dollar problem, and engineers from Northwestern University have found one. They have developed a strategy that prevents frost from forming in the first place.
Achieving Frost-free Regions for Long Periods of Time
So, what’s the solution? Well, one of the main components of the solution that NU engineers have discovered revolves around graphene.
Extracted from graphite, graphene is made of pure carbon, one of the most important and fourth most abundant natural elements.
This material is particularly known for being lightweight. At just one atom thick, graphene is the thinnest known compound. It is also pretty tough, about 100-300x stronger than steel. In addition to its flexibility, graphene is the best conductor of electricity and is renowned for its uniform absorption of light.
All these features give graphene promising applications in areas like composites, electronics, sensors and imaging, energy, telecommunications, and biomedical technologies.
Northwestern University researchers are now using this material to tackle frost. Specifically, they are using graphene oxide (GO), a compound proposed over a century and a half ago and has been used in recent years as a potential starting material for the mass production of graphene.
This carbon-based nanomaterial, known much before graphene, is produced through the chemical oxidation of natural graphite by strong oxidants.
In the new study, the engineers found that changing the texture of a surface and then adding a thin layer of GO completely prevents the formation of frost on surfaces for a week, potentially even longer.
What graphene oxide does is it attracts and then traps water vapor—water in gaseous form—within its structure, effectively preventing the water from freezing. When combined with a macrotexture surface, it leads to a prolonged period of high supersaturation.
This week-long frost prevention is a thousand times longer than what is achieved by the existing, advanced anti-frosting surfaces. On top of that, the new surface design, which is scalable, is also resistant to scratches, cracks, and contamination.
Incorporating this textured surface into infrastructure can help companies and governments save billions of dollars annually in energy inefficiencies and avoid maintenance costs, estimates researchers. According to study lead Kyoo-Chul Kenneth Park, who’s an assistant professor of mechanical engineering at McCormick School of Engineering at NU:
“Unwanted frost accumulation is a major concern across industrial, residential, and government sectors.”
This fiscal year, the university secured a record $1.05 bln in research funding, an increase of 5% from last year.
Park pointed to how the power crisis of 2021 in Texas cost a whopping $195 bln in damage, which was the direct result of ice, frost, and extreme cold conditions for over 5 days, affecting 4.5 million households.
“Thus, it is critical to develop anti-frosting techniques, which are robust for long periods of time in extreme environmental conditions.”
– Park, a faculty affiliate of the International Institute for Nanotechnology and the Paula M. Trienens Institute for Sustainability and Energy
However, we need not only anti-frosting techniques but also those that are easy to fabricate as well and implement. With that in mind, the researchers created their hybrid anti-frosting method, which is durable, scalably, easy to fabricate via 3D printing, and can stave off frosting for weeks.
Combining Leaves’ Geometry with GO’s Hygroscopic Properties
The new study actually builds upon the previous work from Park’s team in 2020, during which they found that changing the texture reduces frost formation by as much as 60%. Meanwhile, adding textures of millimeter-scale—optimized, jagged series of peaks and valleys as observed in nature—to a surface can bring down the formation of frost by up to 80%.
For this discovery, the engineers took inspiration from the geometry of mint leaves. As Park explained at the time, the convex regions of a leaf see more front formation than the concave (veins) regions, which actually get “much less frost.”
While this has been noticed for a long time, there has been no explanation as to why and how this happens. He said:
“We found that it’s the geometry—not the material—that controls this.”
The rippling geometry of leaves means frost forms on peaks where condensation is enhanced but rarely in the valleys, where condensation is suppressed. Whatever small amount of condensed water is in the valleys of wavy surfaces evaporates, leading to a frost-free area.
Interestingly, even using a surface material that attracts water, the same result is observed: water evaporates from the valleys when below the freezing point.
Using this information, the team went on to find the optimal surface texture, which was a surface containing millimeter-tall peaks and valleys with only 40-60-degree angles in between.
The thin line of frost that still forms on this surface’s peaks can be defrosted with considerably less energy and removes the need for using surface coatings or liquids with lower frosting points.
“The no-frosting region initiates the defrosting process. So it would reduce the materials and energy used to solve frosting problems.”
– Park
In the new study, the team introduced graphene oxide (GO) in the mix, which is added to flat valleys to reduce frost formation completely, even in the valleys.
GO was chosen due to its exceptional hygroscopic properties, which is the ability of the material to attract and hold water molecules via absorption. The water vapor absorption rate of GO is 2x that of silica gel. Then, GO has the intrinsic ability to suppress the freezing of intercalated water molecules through nanoconfinement effects.
The new surface also has tiny bumps, having a peak-to-peak distance of 5 mm. A thin layer of GO, which is only 600 microns thick, is coated on the valleys between peaks. According to Park:
“Graphene oxide attracts water vapor and then confines water molecules within its structure. So, the graphene oxide layer acts like a container to prevent water vapor from freezing.”
Adding graphene oxide to the macrotexture surface helped the surface resist frost at high supersaturation for a long stretch, in turn making the experimental hybrid surface “a stable, long-lasting, frost-free zone.”
You can watch a demonstration of this technique on YouTube here, which is posted on the official NU channel:
It shows how frost forms on the surface’s honeycomb-shaped peaks while the flat valleys remain frost-free. In the video, the surface on the right has a thin coat of GO.
To showcase the superiority of its method, the Park team compared it with other advanced anti-frosting surfaces.
Compared to 100% frost formation resistance for 150 hours, super water-repellent and lubricant-infused surfaces were only able to resist 5-36% of frost formation, and that too for just 5 hours. Then there’s the matter of susceptibility of other anti-frosting surfaces to damage from scratches or contamination, “which degrades surface performance over time.”
Park’s hybrid macrotexture-graphene oxide surface, on the other hand, is robust against such damages and, as such, extends the life of the surface.
As of now, there’s no ‘one-size-fits-all’ approach available in the market due to the specific needs of different applications. For instance, airplanes need just seconds of frost resistance in comparison to power lines, which consistently operate in cold environments and may need days or weeks of frost resistance.
The new technique, according to the researchers, can be used to design airplane wings as well as power lines with reduced ice adhesion in order to significantly reduce yearly maintenance costs. The method can further help prevent energy inefficiencies and aid in the safe operation of infrastructure in cold environments.
Protecting the Infrastructure from Harsh Climates
Cold climates come with the coziness of warm blankets, hot chocolates, and festive feelings. But at the same time, it brings its own set of problems, particularly in the form of health issues and infrastructure damage.
The buildup of ice and snow can compromise the performance and safety of ships, car windshields, power lines, wind turbines, and airplanes. That’s why researchers have been looking to address these problems.
Surfaces that can mitigate ice growth, in particular, have been getting a lot of interest, as we saw in the latest study too, as a cost-effective alternative.
As we shared earlier this year, researchers from Drexel’s College of Engineering also came up with self-heating concrete that clears snow as well as freezing rain on their own, without needing anyone to scrap, shovel, or salt, that negatively affects surfaces for three years.
In order to expand the operational life of roadways and other infrastructure and save money on their maintenance, researchers used low-temperature phase change material (PCM) liquid paraffin for this self-heating concrete. When the temperature falls to ∼0°C or 32°F, the material releases heat and turns from liquid to solid, resulting in the gradual melting of the ice.
Then, a team of researchers in Canada developed a surface that repels snow on its own by combining the attributes of thermal insulation and superhydrophobicity. The group found that silica aerogel minimized snow melting and prevented adhesive ice layer formation, while superhydrophobicity reduced the contact area and repelled interfacial meltwater droplets, further lowering the snow adhesion strength.
In another study, Chinese researchers focused on superhydrophobic surfaces with excellent anti-icing and water-repellent performances at low temperatures. These surfaces, unlike widely studied superhydrophobic surfaces—particularly for their potential aerospace applications—are not as well-reported.
To create such surfaces, the researchers etched square micropillar arrays onto multiwalled carbon nanotube (MWCNT)/poly(dimethylsiloxane) (PDMS) films, resulting in triple ice-phobicity that remains activated even at −40 °C.
Researchers believe this opens up new possibilities for bionic smart multifunctional materials in ice-phobic applications.
A separate study on slippery liquid-infused porous surfaces (SLIPSs), widely used as an effective passive approach to reduce icing disasters, found that certain features are key for durability. Small pores (about 100 nm), which exert strong capillary pressure on the lubricant, and high porosity (66%), which provides a large lubricant-liquid contact ratio, are particularly beneficial for durable anti-icing SLIPS.
All-season smart-roof coating is another one that keeps buildings warm during the winter and cool during the summer. This coating doesn’t require any electricity or gas; it uses TARC, or temperature-adaptive radiative coating, which turns off the radiative cooling in winter automatically to ensure there’s no energy waste.
Besides targeting surfaces, other advances made in infrastructure improvement while saving maintenance costs and protecting the environment involve adaptive roof tiles, which feature a radiative switch to respond to different temperatures.
Companies to Look At
Now, we’ll take a look at companies that can benefit from the development of anti-frost technologies as well as those that are helping advance this field.
In the aerospace sector, Lockheed Martin (LMT -0.41%) is one popular name, and frost-resistant surfaces can help enhance the performance and durability of both its military and commercial aircraft. The $129.26 bln market cap company’s shares are currently trading at $545.35, up 20.32% this year. It has an EPS (TTM) of 27.65, a P/E (TTM) of 19.73, and a dividend yield of 2.42%.
Lockheed Martin Corporation (LMT -0.41%)
Boeing (BA +0.31%) is another one from the aerospace sector that also invests heavily in de-icing technologies to improve safety and efficiency. However, this $95 bln company’s shares are currently trading at $155.33, down 40.69% YTD due to its planes falling apart and whistleblowers dying.
The Boeing Company (BA +0.31%)
Companies like 3M (MMM -1.08%) also play an important role due to their involvement in materials innovations. This $69bln market cap company’s shares are up 16.37% YTD as they trade at $127.22 with an EPS (TTM) of 7.63 and P/E (TTM) of 16.68 while paying a dividend yield of 2.20%.
1. Raytheon Technologies (RTX -0.63%)
The graphene oxide-based technique from NU can help this aviation and defense tech provider improve safe operations in cold environments. Raytheon is a $158 bln market cap company whose shares are trading at $118.75, up 41.13%, while having an EPS (TTM) of 3.52, a P/E (TTM) of 33.78, and a dividend yield of 2.12%.
RTX Corporation (RTX -0.63%)
For Q3 2024, sales were reported to be $20.1 billion, up 6% from the previous year, while the backlog was $221 billion. This backlog included $131bln in commercial and $90bln in defense segments. Free cash flow at the end of the quarter was $2bln, while $1.1bln of capital was returned to shareowners.
2. Proto Labs (PRLB -10.89%)
For these new technologies to rapidly get into the market, they need to be produced just as quickly. And that’s where companies like Proto Labs can help. It utilizes 3D printing, injection modeling, and CNC machining to manufacture parts. This $955.6 mln market cap company, whose shares are trading at $38.75, is down 2.46% while having an EPS (TTM) of 0.94 and a P/E (TTM) of 40.30.
Proto Labs, Inc. (PRLB -10.89%)
For Q3 2024, it reported $125.6mln in revenue, which was a 3.9% decrease from Q3 last year. Net income came in at $7.2 million, while EBITDA was $17.5 million. It served 22,511 customer contacts during this period. The company, however, generated its highest quarterly operating cash flow in four years, which CEO Dan Schumacher said “is a testament to the profitability of Protolabs’ model against any macro backdrop.”
Conclusion
The latest discovery by Northwestern University researchers to significantly reduce frost formation on any surface holds substantial potential in making people’s lives smoother by lowering the number of canceled flights, which can get grounded by the slightest layer of frost, and reducing the use of strong de-icing chemicals.
As a robust anti-frosting tool, the hybrid macrotexture-GO surface can further help decrease the amount of energy and cost needed in defrosting. This way, it can find strong application in industries requiring long passive anti-frosting times, including aerospace, power distribution, and transportation.
Overall, such advancements in anti-frost technology can help provide durable and sustainable solutions to weather-related challenges that are experienced every year, which, in turn, help build more efficient and resilient infrastructure and have a significant economic impact.
Click here to learn all about self-heating concrete.