Developing a durable anti-frost surface: Integrating the passive anti-icing properties of salt, saline, and bulk ice for enhanced frost prevention

Abstract

Icing on surfaces presents significant challenges for the aviation industry and life in cold alpine regions. Developing smart surfaces to mitigate icing effects is highly desirable. When icing cannot be completely avoided in the atmosphere, limiting it to a small area on the surface is a practical solution. We have created a hydrophilic pattern on superhydrophobic surfaces using laser fabrication, which allows saline droplets to adhere to the pattern. As these droplets dry, salt grains cover the pattern, making the surface primarily superhydrophobic. Under frost conditions, the salt grains turn into saline beads, which then freeze into ice beads. Frost forms only on the tops of these ice beads within the pattern. Due to the lower saturated vapor pressure of salt, saline, and ice compared to the supersaturated vapor pressure for condensation, there is not enough humidity around the pattern for water vapor to condense and form frost. As a result, water vapor continuously deposits inside the pattern, significantly reducing frost formation around it. This combination of salt, saline, and ice, with their lower saturation vapor pressures below zero Celsius, ensures a dry perimeter during rapid temperature drops and increased humidity. By designing the pattern size appropriately, the dry perimeters overlap, keeping the entire surface outside the pattern free of frost. This approach offers a promising solution for reducing frosting on surfaces.