Nanotextured Surfaces for Anti-Icing

Abstract

Unwanted ice formation on surfaces is ubiquitous and often leads to catastrophic events, resulting in economic loss and costing human lives. Superhydrophobic nanotextured surfaces can circumvent such surface icing events either by minimizing the contact time between supercooled metastable liquid and surface or by suppressing ice nucleation events. However, such surfaces may not effectively inhibit icing under certain conditions. For example, superhydrophobic surfaces lose their non-wetting property when exposed to dynamically impacting water droplet/jet beyond a certain threshold velocity. Also, under high humidity conditions, surfaces become ineffective due to the formation of a frost layer. It has been shown that the roughness and thermal conductivity of the surface play a vital role to overcome aforementioned problems. In fact, substrate with high thermal conductivity (e.g. metals) can avoid the formation of the frost layer under. On the other hand, surfaces with precisely controlled nanotextures are beneficial to achieve high drop/jet impalement stability. With this perspective, we fabricated textured surfaces on aluminium, which has a plethora of industrial applications due to its high thermal conductivity and abundance in nature. Using a combination of wet etching and electrochemical approaches three kinds of micro/nano hierarchical surfaces were manufactured. Next, the surfaces were coated with fluorosilane to render them hydrophobic. We evaluated droplet/water-jet meniscus stability of the resulting surfaces, and discussed the role of different kinds of nanotextures on the impalement resistance of the surface.