Harvard University researchers say they have invented a treatment that keeps any metal surface free of ice and frost by effortlessly shedding any condensation through gravity.
The discovery has “direct implications” for a wide variety of metal surfaces used in wind turbines, aircraft, marine vessels, construction and other applications, says the research team, led by Joanna Aizenberg, Professor of Materials Science at Harvard’s School of Engineering and Applied Sciences (SEAS).
Photos: Harvard School of Engineering and Applied Sciences
|Still images extracted from movies show simulated ice formation by deep freezing (-10°C) in high humidity and subsequent deicing by heating.|
The new approach improves on an ice-repellent coating that Aizenberg’s team unveiled last fall. Researchers have since found that the earlier version, inspired by the water-repellant lotus leaf, prevented ice but failed under high humidity as a surface became coated with condensation and frost.
Locking in Lubricant
To combat the problem, the researchers have invented a new technology suited for both high humidity and extreme pressure, Harvard reports in a release. SLIPS (Slippery Liquid Infused Porous Surfaces) are designed to “expose a defect-free, molecularly flat liquid interface, immobilized by a hidden nanostructured solid.”
Water drops, condensation, frost, and even solid ice easily slide off the ultra-smooth slippery surface, the team says.
The challenge was to apply the technology to metal surfaces, but the team developed a way to coat the metal with a rough material to which the lubricant can adhere. The non-toxic, anti-corrosive coating can be “finely sculpted to lock in the lubricant,” said Harvard.
The coating can be applied over a large scale and on arbitrarily shaped metal surfaces, the university reports.
A report on the technology was recently published in the journal ACS Nano.
Deep Freeze Testing
The researchers applied the coating to refrigerator cooling fins and tested it under a prolonged, deep-freeze condition. They said the material “completely prevented frost far more efficiently and for a longer time” than current “frost-free” cooling technology.
|The team has developed a scalable method to coat an aluminum surface with a nanostructured polymer layer that converts to a slippery liquid-infused porous surface (SLIPS). SLIPS can delay ice formation and shed liquids and solids, even under high humidity, researchers say.|
“Unlike lotus leaf-inspired icephobic surfaces, which fail under high humidity conditions, SLIPS-based icephobic materials, as our results suggest, can completely prevent ice formation at temperatures slightly below 0°C while dramatically reducing ice accumulation and adhesion under deep freezing, frost-forming conditions,” said Aizenberg.
The technology also dramatically reduces energy costs since no heat is required for de-icing, the team said.
The work was supported in part by the Materials Research Science and Engineering Center (MRSEC) at Harvard and the Wyss Institute for Biologically Inspired Engineering.
Said Aizenberg: “This new approach to icephobic materials is a truly disruptive idea that offers a way to make a transformative impact on energy and safety costs associated with ice, and we are actively working with the refrigeration and aviation industries to bring it to market.”