铜基超疏水表面防覆冰/抗霜冻特性分析

Anti-icing/anti-frost performers of copper-based superhydrophobic surfaces

超疏水表面具有良好的防覆冰性能,有望改善低温条件下设备和设施的可靠性。本文采用氨气腐蚀法,制备具有微纳结构的铜表面,通过低表面能氟硅烷修饰后,金属铜表面表现出超疏水特性,其水接触角可达152.1°。利用电镜扫描、接触角测量、结冰和结霜实验分别对超疏水铜表面的表面结构、湿润性能和防覆冰性能进行研究。结果表明,超疏水表面的防覆冰/抗霜冻性能不仅与表面的粗糙度有关,还受液滴在固体表面的湿润状态的影响。当液滴在具有微-纳米结构的超疏水表面处于Cassie状态时,液滴与金属表面的接触面积小,液滴结冰速率较慢,金属表面同时具有较好的防覆冰和抗结霜性;而当液滴在金属疏水表面处于Wenzel状态时,霜晶与固体表面的接触面积增加,加快霜层的生长,金属表面的抗结霜性明显降低。

The superhydrophobic surface has good anti-icing properties and is expected to improve the reliability of facilities under low temperature conditions.Micro-nano structures were fabricated on the copper surfaces by chemical etching with ammonia gas,after modification by the low surface energy material fluoroakylsilane(FAS),the copper surfaces exhibited superhydrophobic properties,with a water contact angle of about 152.1°.The wettability,the surface micro-structure and the anti-icing behavior of the copper surfaces were investigated by means of contact angle measurement,SEM,and freezing experiments,respectively.The results indicate that,the anti-icing and anti-frosting performers of the superhydrophobic surfaces are not only depend on the surface roughness,but also relate to the state of the droplets on the surface,if the droplets on the superhydrophobic surfaces are in the Cassie model,the contact area between the droplets and the surfaces are small,the copper surfaces have good anti-icing and anti-frosting properties.While the droplets on the copper hydrophobic surfaces are in the Wenzel model,the frost layer grows faster as the contact area between the frost crystal and the solid surfaces increased,and the frost resistances of the copper surfaces decrease significantly.