Superhydrophobic Self-Assembled Silane Monolayers on Hierarchical 6082 Aluminum Alloy for Anti-Corrosion Applications

Abstract

In this work, a two-stage methodology to design super-hydrophobic surfaces was proposed. The first step consists of creating a rough nano/micro-structure and the second step consists of reducing the surface energy using octadecyltrimethoxysilane. The surface roughening was realized by three different short-term pretreatments: (i) Boiling water, (ii) HNO3/HCl etching, or (iii) HF/HCl etching. Then, the surface energy was reduced by dip-coating in diluted solution of octadecyltrimethoxysilane to allow the formation of self-assembled silane monolayers on a 6082-T6 aluminum alloy surface. Super-hydrophobic aluminum surfaces were investigated by SEM-EDS, FTIR, profilometry, and contact and sliding angles measurements. The resulting surface morphologies by the three approaches were structured by a dual hierarchical nano/micro-roughness. The surface wettability varied with the applied roughening pretreatment. In particular, an extremely high water contact angle (around 180°) and low sliding angle (0°) were evidenced for the HF/HCl-etched silanized surface. The results of electrochemical tests demonstrate a remarkable enhancement of the aluminum alloy corrosion resistance through the proposed superhydrophobic surface modifications. Thus, the obtained results evidenced that the anti-wetting behavior of the aluminum surface can be optimized by coupling an appropriate roughening pretreatment with a self-assembled silane monolayer deposition (to reduce surface energy) for anticorrosion application.

Effect of Chemical Surface Texturing on the Superhydrophobic Behavior of Micro–Nano-Roughened AA6082 Surfaces

“…The wide-range jagged plateau in the profile had a higher probability to have neighboring hydroxyl groups. Instead, the peaks, because of their narrow and sharp shape, are less susceptible to reaction with the silane molecules due to the limited number of the OH groups in this surface profile area [ 82 ].…”

Stability of Octadecyltrimethoxysilane-Based Coatings on Aluminum Alloy Surface

“…Self-assembled ultrathin monolayers of organosilanes, which are one of the most commonly used low-surface energy coatings (often referred to as ‘hydrophobizers’), have been applied on metal, oxide, ceramic and Si substrates [ 1 , 8 , 14 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. For several decades, various organosilanes, including fluorinated alkylsilanes (FASs), have been used as hydrophobizing agents deposited either via immersion in liquid bath [ 1 , 8 , 14 , 21 , 26 , 27 , 32 , 33 , 34 , 35 ] or from gas phase [ 13 , 27 ].…”

“…Self-assembled ultrathin monolayers of organosilanes, which are one of the most commonly used low-surface energy coatings (often referred to as ‘hydrophobizers’), have been applied on metal, oxide, ceramic and Si substrates [ 1 , 8 , 14 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. For several decades, various organosilanes, including fluorinated alkylsilanes (FASs), have been used as hydrophobizing agents deposited either via immersion in liquid bath [ 1 , 8 , 14 , 21 , 26 , 27 , 32 , 33 , 34 , 35 ] or from gas phase [ 13 , 27 ]. Apart from water repellency, which is normally expected in case of alkylsilanes, organosilane layers were also reported as part of anti-ice (or ice-phobic) surfaces [ 4 , 8 , 14 , 16 , 17 , 36 , 37 ], as well as part of anticorrosive coatings [ 21 , 22 , 23 , 27 , 32 , 33 , 38 , 39 , 40 ].…”

The Effect of Sugar Content for the Wettability of Superhydrophobic Aluminum Substrate

“…Ruijin Liao et al used CuCl2, HCl continuous chemical etching and hexadecyltrimethoxy silane surface modification to prepare a micro-nano superhydrophobic aluminum surface [9]. Amani Khaskhoussi et al used boiling water, HNO3/HCl etching or HF/HCl etching to achieve surface roughening, and then reduced the surface energy by octadecyltrimethoxysilane (TCODS) to prepare a nano/micro-roughness dual layer structure on the surface of 6082-T6 Al [10].…”