Identification of the mechanism that confers superhydrophobicity on 316L stainless steel

Castellote-Alvarez

Escobar

et al. 2018

MSF

Self Cite

This study develops a new, facile and rapid process bioinspired on rice leaf with the aim of producing a hybrid composite coating in a first attempt to obtain a superhydrophobic coating with enhanced erosion resistance properties. Rice leaves (Oryza sativa L.) are made of hierarchical structures consisting of micropapillae and waxy nanobumps which confer to the surface a contact angle of 164° as Lotus leaf does. In particular, rice leaves accumulate amorphous silica inside and on the surface with various morphologies. This kind of silica is produced by absorbing silicates from the soil under specific conditions of temperature and pressure. The presence of biosilica in rice leaves is useful for preventing diseases or improves mechanical properties of the leaves. Single-step and two-step processes are the two strategies applied for generating a superhydrophobic coating by electrochemical deposition of ZnCl2, α-Al2O3 and lauric acid (C11H23COOH) onto commercial pure aluminum substrate. The static contact angle measured on the coating gives values of 170° and 1° for the sliding angle conducing to a coating with superhydrophobic and self-cleaning properties. Various characterization techniques are used to determine chemical and morphological structure such as FESEM, XPS or FTIR. On one hand, in morphological analysis, flower-like structure is obtained with petals thickness of 70nm corresponding to the nanostructured contribution to the system. On the other hand, chemical analysis concludes the generation of zinc laurate (Zn (C11H23COO)2) as a major compound contributing to the reduction of surface tension and increasing the superhydrophobic character of the coating as well.

Section: Resultsmentioning

confidence: 99%

Superhydrophobic Coating Bioinspired on Rice Leaf: A First Attempt to Enhance Erosion Resistance Properties at Environmental Conditions with Ceramic Particles

Castellote-Alvarez

Escobar

et al. 2018

MSF

Self Cite

“…This, results in large contact angle (CA = 170°) and small sliding angle (SA = 1°). The HR-XPS C-1s [23,32] located at 286 eV is analysed (Table 1, Fig. 4b).…”

Section: 1characterization Of the Superhydrophobic Composite Coating Of Aluminium Surfacesmentioning

confidence: 99%

“…In electrodeposition, a single step can be used to generate an SH coating on aluminium [22] or 316L stainless steel [23,24], with lauric acid and nickel chloride. In order to enhance the properties of materials or coatings, several compounds can be selected [25]; however, ceramics play an important role in increasing resistance to chemical agents and mechanical wear.…”

Section: Introductionmentioning

confidence: 99%

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

Surface and Coatings Technology

Castellote-Alvarez

Escobar

et al. 2019

Self Cite

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 2 water erosion. Finally, a water/oil separation test determined 99% separation efficiency in hexane and ether petroleum systems, in a laboratory-made storage tank.

“…Most of these methods involve the use of fluoro compounds and complex preparation processes. Here, taking into account previous studies [6], [7], we propose a new eco-friendly approach to prepare superhydrophobic aluminium surfaces, by reducing the surface free energy of an initially anodized aluminium surface by coating of the surface with a fatty acid. The goal of the initial anodizing is to improve the corrosion resistance and the mechanical properties of the aluminium previously to the organic coating.…”

Section: Introductionmentioning

confidence: 99%

Superhydrophobic and Corrosion Protective Coating on Aluminium

Romero

Llorca-Isern

et al. 2018

MSF

Self Cite

Industrial application of superhydrophobic surfaces is limited by the unsatisfactory mechanical properties of the material. Combining chemical etching and anodization terraced features containing aluminium oxide on different aluminium alloy surfaces were produced. After modified by fatty acid, the surfaces were superhydrophobic and they showed self-cleaning effect. The highest contact angle was obtained after forming hierarchical structures with a solution free of fluorine compounds; therefore, the process is considered eco-friendly. The alumina formed in the coating process promotes an improved corrosion resistance. The present study has three main objectives: to identify the molecules responsible for superhydrophobicity, the mechanism by which superhydrophobicity is produced, and consequently the influence of variables such as anodization time on the proposed processing method. We use time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) techniques to identify each compound involved in the final surface, by paying close attention to the analysis of the mechanism by which the chemical reaction proceeds. The morphology of the superhydrophobic surfaces was further observed by scanning electron microscope (SEM) and atomic force microscopy and was used to elucidate the effect of the anodization time in the properties of the superhydrophobic material.