Robust and superhydrophobic coating highly resistant to wear and efficient in water/oil separation

• Published in: Surface & coatings technology 2019-04, Vol.364, p.330-340
• Main Authors: Rius-Ayra, Oriol, Castellote-Alvarez, Roger, Escobar, Ana M., Llorca-Isern, Nuria
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Chemical analysis; Coating; Composite; Contact angle; Deposició (Metal·lúrgia); Electrochemistry; Electrodeposition; Electroquímica; Fatty acids; Hierarchical structure; Hybrid composites; Hydrophobic surfaces; Hydrophobicity; Lauric acid; Metal surfaces; Organic chemistry; Plating; Robust; Separation; Storage tanks; Substrates; Superfícies hidrofòbiques; Superhydrophobic; Water erosion; Water/oil separation; Wear; Wear resistance; Zinc chloride
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2019.01.077

Here, we report a straightforward and rapid process using fatty acids to produce a stable superhydrophobic hybrid composite coating on aluminium substrate which is highly resistant to wear under environmental conditions. Furthermore, this novel superhydrophobic metal surface is highly efficient at separating of water/oil systems. The single-step process we adopt involves electrochemical deposition of ZnCl2, α-Al2O3 and lauric acid (C11H23COOH) onto commercial pure aluminium substrate. The resultant static contact angle (170°) and sliding angle (1°) are those of a superhydrophobic coating with self-cleaning properties; while chemical analysis shows that this is the result of generation of zinc laurate (Zn(C11H20COO)2) as a major compound that increases the superhydrophobic character of the coating, generating a flower-like structure 70 nm thick. Different wear tests show the coating is resistant to severe conditions, confirming its real potential against weathering, including sand and water erosion. Finally, a water/oil separation test determined 99% separation efficiency in hexane and ether petroleum systems, in a laboratory-made storage tank. [Display omitted] •A single-step process is used for generating a superhydrophobic composite coating.•α-Alumina enhances erosion resistance after several tests in severe conditions.•A laboratory-made tank presents high efficiency of water/oil separation.