Nano surfaces that can delay ice from forming
As many of you may know ice could be a huge problem in everyday life. For many of us who live in the North East of the US, dealing with ice and snow during our commute to work in the winter months is part of everyday life. But actually ice can have major impact in many other important areas that might not be so obvious. For examples, ice accretion on surfaces of aircrafts, wind turbine blades, oil and gas rigs and heat exchangers, to name a few examples, causes problems with respect to efficiency and cost of operation. Significant ice accretion on surfaces of an aircraft can cause problems during lift off and change the aerodynamics of the wings during flight; ice built up on wind turbine blades in cold climates can reduce the efficiency of power generation. I also need to mention that these are not new problems and there has been significant research and progress to combat ice in the past six decades. A solution that is particularly attractive is an icephobic (or ice-resistance) coating. Other solutions are typically based on heating/ melting or mechanically breaking the ice, which end up being expensive since they require a lot of energy for their operation and also add weight which is not a desirable feature. So this was a challenge that our team at the Global Research decided to work in 2005.
Much of our earlier efforts has been towards development of the so-called “low ice adhesion coatings”. Ice sticks to these coatings, but the nice thing is that you only need a very small force to remove the ice (the ice block’s weight or the drag forces provided by the wind are sometime sufficient). Our team has been very successful in making very low ice adhesion coatings. These days we are taking on two major challenges: 1-improve the robustness of the coatings for real life applications (the coatings have to survive harsh conditions and be resistant to sand and rain erosions); 2- create coatings that are not only low-ice-adhesion but also “ice resistant” that means they delay ice formation! We have recently developed model nanostructured surfaces with periodic arrays of posts that delay the onset of ice formation by more than a minute. We have also studied the fundamental physics behind this observation, which is very important for developing more realistic coatings that can one day be used in real-life applications. We have learned that on these model water repellent surfaces, decreasing the water-substrate contact area plays a dual role in delaying ice formation: first by reducing heat-transfer and second by reducing the probability of ice nucleation at the water-substrate interface.
I recently attended the American Physical Society March Meeting in Boston and gave a talk about our findings. I was very excited to talk about our work with other researchers from academia and industry. This exchange of information is always very helpful and inspiring. If you are interested in learning more about the work and ice nucleation delay, please read our recent paper in Langmuir (2012), volume 28, pages 3180−3186.