Abstract
Inspired by the array microstructure of natural superhydrophobic surfaces (lotus leaf and cicada wing), an array microstructure was successfully constructed by high speed wire electrical discharge machining (HS-WEDM) on the surfaces of a 7075 aluminum alloy without any chemical treatment. The artificial surfaces had a high apparent contact angle of 153° ± 1° with a contact angle hysteresis less than 5° and showed a good superhydrophobic property. Wettability, contact time, and the corresponding superhydrophobic mechanism of artificial superhydrophobic surface were investigated. The results indicated that the micro-scale array microstructure was an important factor for the superhydrophobic surface, while different array microstructures exhibited different effects on the wettability and contact time of the artificial superhydrophobic surface. The length (L), interval (S), and height (H) of the array microstructure are the main influential factors on the wettability and contact time. The order of importance of these factors is H > S > L for increasing the apparent contact angle and reducing the contact time. The method, using HS-WEDM to fabricate superhydrophobic surface, is simple, low-cost, and environmentally friendly and can easily control the wettability and contact time on the artificial surfaces by changing the array microstructure.
Highlights
High apparent contact angles (APCAs), low contact angle hysteresis, and the highest possible stability of the Cassie wetting state are three important criteria for true superhydrophobicity [1,2,3,4,5].The superhydrophobic property of a surface is mainly determined by the cooperation of the geometric microstructure and the low energy surface [6,7,8]
A 7075 aluminum alloy was used as the substrate to fabricate an artificial superhydrophobic surface
The wettability, contact the lotusfabricated leaf and cicada wing both possessany an chemical array microstructure, which is a verythe important time factor on thefor artificial surface, and the decrease of the contact time have been studied in this research
Summary
The superhydrophobic property of a surface is mainly determined by the cooperation of the geometric microstructure and the low energy surface [6,7,8]. Superhydrophobic objects, such as lotus leaf, taro leaf, and India canna [9], are widespread in nature. Superhydrophobic surfaces have numerous promising properties, such as non-wetting [10], self-cleaning [11], anti-icing [12], lubrication [13], condensation management [14], and small flow resistance [15]. Some of the above methods need severe conditions or fabricate superhydrophobic surfaces on soft materials such as polymers [21,22] and colloidal materials [23,24], which limit the application of Materials 2017, 10, 254; doi:10.3390/ma10030254 www.mdpi.com/journal/materials
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