High-strength coating controls crack formation to keep surfaces ice-free
Keeping airplane wings ice-free is critical to flight safety, but it’s not the easiest of problems to solve. De-icing solutions with heavy chemicals that are sprayed onto aircraft ahead of take-off can keep the wing surfaces clean and functional, but this is labor-intensive and environmentally damaging. Engineers at the University of Houston have put forward a new solution, developing an ice-shedding surface coating they say is 100 times stronger than other state-of-the-art materials.
The shortcomings with current methods of de-icing surfaces has inspired many researchers to pursue more efficient and environmentally friendly solutions. These have included systems that use heat to melt the ice away, drawing on special graphene coatings, passive solar systems or even electrified concrete for airport runways. Other materials rely on special grooves to siphon moisture away and prevent ice buildup, or phase-change liquids to repel water away.
The approach taken by the University of Houston engineers centers on the way solid objects detach from surfaces. This process is driven by the application of force and the resulting formation of cracks at the interface. These fractures might start small, but will continue to grow until the object is released. The researchers were able to essentially manipulate this process with the development of what they call a “fracture-controlled surface.”
The material is heterogenous, with a varying mechanical and chemical composition that is carefully engineered to initiate crack formation at the interface, direct energy toward those cracks and accelerate their growth. This means that ice doesn’t attach to the material, but perhaps more importantly, that the material exhibits great strength.
The scientists say a shortcoming with similar ice-shedding materials is that their limited durability has prevented their widespread application. Their results indicate that this new material is 100 times stronger than any others in the space, and in high-speed testing by Boeing in rainy conditions, the material was found to outperform current state-of-the-art aerospace coatings.
“The primary challenge in developing ice-shedding materials is finding materials with both low ice adhesion and good durability,” said study lead Hadi Ghasemi.
The scientists believe the material may find use beyond the realm of aerospace, with wind farms one of the possibilities raised. There it could help avoid or minimize the buildup of ice on turbines that compromises their power generation, for example.
"We developed a new concept in which, through material design, you can significantly accelerate the crack formation and growth and easily remove external objects from the surface,” said Ghasemi. “This concept is implemented to develop materials that are highly durable, and ice does not attach to these materials. Fracture-controlled surfaces provide a rich material platform to guide future innovation of materials with minimal adhesion while having very high durability.”
The research was published in the journal Materials Horizons.
Source: University of Houston