The Hydrophobicity Analysis And Anti-Frost Characteristics Research Of Super-Hydrophobic Aluminum Surfaces

Roughness and low surface energy materials are two basic elements in preparation of super-hydrophobic surface on metals. This paper chose the most widely used aluminum as the base and prepared super-hydrophobic surface via chemical etching following modified with different low energy materials. The water contact angle of the surface can be up to159°and the contact angle hysteresis can be as low as3.5°The hydrophobicity analysis of the solid surface often starts with roughness and low surface energy materials. Based on the previous research, this article focused on the impact of low surface energy. Through comparison of the low surface energy materials used to modify the surface, as used herein, fluorosilane, lauric acid, polytetrafluoroethylene, we found that the hydrophobicity of the surface is not only related to the characteristic of hydrophobic groups, but also to the arrangement of the hydrophobic groups.At low temperatures, frost experiment was carried out on the super-hydrophobic aluminum surface and common aluminum surface with humidifier to produce micron water droplets. It was found that the super-hydrophobic aluminum surface can postpone frost for30-60min even though the amount of frost on the surface was more than ordinary aluminum surface when the temperature is higher than-15℃. While the temperature is below-15℃,both of the two surfaces start frosting simultaneously.However, the amount of frost on the super-hydrophobic aluminum surface significantly lower than that on the common aluminum surface.In this paper, freezing experiments were also carried out on super-hydrophobic surface and common aluminum surface at-5℃and-10℃respectively. We found that the amount of ice on super-hydrophobic aluminum surface was less than that on common aluminum surface. It was also found that the sprayed water on super-hydrophobic surface was droplet-shaped and hard to freeze while the water formed a water film that can be frozen quickly on common surface.This paper also carried out ice-adhesion test experiment to compare the capability of deicing of the two surfaces. Place the super-hydrophobic aluminum surface and common aluminum surface into the cylindrical molds separately, then pour same amount of water into them and then freeze for2hours at-20℃. Remove the two sheets of aluminum from the molds and clip them on the centrifuge device. We can calculate the ice-adhesion force on the different aluminum surfaces using the centrifugal force when the ice detach from the surface. Experimental results showed that the adhesion of ice on the super-hydrophobic aluminum surface is only1/3of the common aluminum surface.