Preparation Of Bionic Surface And Its Anti-Freezing And Anti-Ice Properties Of Cold-Resistant Bamboo Leaves

Condensation is a common phenomenon in high humidity and low temperature environments,it is a transformation of water vapour in the air into a liquid and solid state when it is cold.The problem of icing caused by the accumulation of dew on metal surfaces can cause serious safety problems as well as reducing engineering efficiency.Biomimetic superhydrophobic surfaces inspired by natural biology have shown great potential in everyday life.At the same time,the flourishing of superhydrophobic surfaces has been widely proven thanks to the proficiency of various manufacturing methods.Bamboo leaves were celebrated by the ancients for their good cold-resistant properties.In order to find the reason why the leaves of the corundum can withstand severe cold weather,observations and experiments were carried out on the surface micromorphology,wetting properties and condensation and anti-icing behaviour of the leaves of the corundum.It was found that the waxy layer,micron structure and lamellar nanostructure on the surface of the leaves resulted in differences in the anti-icing behaviour.On the opposite side of the leaf,the superhydrophobicity increases the thermodynamic barrier for droplet condensation nucleation,the waxy layer and micron structure on the surface reduce the contact area between the droplet and the surface,and the lamellar nanostructure provides Laplace pressure to drive the droplet upwards.Thus reasonable micro and nanostructures and low surface energy modifications can promote droplet bouncing and reduce droplet aggregation on the metal surface.The contact area of the droplets on the surface of the bamboo leaf in turn affects the freezing rate of the droplets.In order to further explore the relationship between the condensation and anti-icing properties of the surface of bamboo leaves and its micro-nano structure,low surface energy material and wettability.Based on the microscopic image of bamboo leaves observed by SEM,the bionic composite structure was constructed by laser ablation,and then modified by myridamic acid to prepare the microstructure of bamboo leaves.A self-made condensation/anti-icing platform was used to test the microstructure surface properties of imitated bamboo leaves.The experimental results show that increasing the surface hydrophobicity can significantly improve the thermodynamic barrier of water vapor nucleation,thus delaying the surface water vapor nucleation.The low surface energy material reduces the retarding work of droplet expansion and contraction,and makes the rebound efficiency of droplet up to 21%,and the contact time of droplet is only 10.75 ms.In the anti-icing process,the actual contact area of the droplets on the metal surface will affect the freezing rate of the droplets.The smaller the contact area is,the slower the freezing rate will be.Compared with the bare substrate,the icing time is 8 times longer.