Chemical Nature of Superhydrophobic Aluminum Alloy Surfaces Produced via a One-Step Process Using Fluoroalkyl-Silane in a Base Medium

Noormohammed, Saleema; Sarkar, Dilip; Gallant, Danick; Paynter, R.W.; Chen, X-Grant

doi:10.1021/am201277x

Cited by 211 publications

(126 citation statements)

References 29 publications

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“…In such a composite system if f1 is assumed to be the solid surface, which in our case is a combination of metallic aluminum and its oxide as revealed by the XPS analysis, and f2 is assumed to be air where θ2 is 180° and as f1 + f2 = 1, the above equation According to Cassie-Baxter model, the water drops do not penetrate the rough irregularities, unlike in Wenzel model, rather they roll off the surface provided the fraction of solid (f1) coming in to contact with the water drop is very small or negligible. We have previously reported such roll off behavior on certain surfaces engineered to mimic from lotus effect [21], [22], [23] and [24]. Again, this model also does not explain the contact angle behavior on our NaOH treated surfaces, since in our case the water drops remain stuck on the surface, although with a contact angle higher than 90°.…”

Section: Methodsmentioning

confidence: 53%

A simple surface treatment and characterization of AA 6061 aluminum alloy surface for adhesive bonding applications

Noormohammed

Sarkar

Paynter

et al. 2012

Applied Surface Science

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145

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Structural adhesive bonding of aluminum is widely used in aircraft and automotive industries. It has been widely noted that surface preparation of aluminum surfaces prior to adhesive bonding plays a significant role in improving the strength of the adhesive bond. Surface cleanliness, surface roughness, surface wettability and surface chemistry are controlled primarily by proper surface treatment methods. In this study, we have employed a very simple technique influencing all these criteria by simply immersing aluminum substrates in a very dilute solution of sodium hydroxide (NaOH) and we have studied the effect of varying the treatment period on the adhesive bonding characteristics. A bi-component epoxy adhesive was used to join the treated surfaces and the bond strengths were evaluated via single lap shear (SLS) tests in pristine as well as degraded conditions. Surface morphology, chemistry, crystalline nature and wettability of the NaOH treated surfaces were characterized using various surface analytical tools such as scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDX), optical profilometry, infrared reflection absorption spectroscopy, Xray photoelectron spectroscopy, X-ray diffraction and contact angle goniometry.Excellent adhesion characteristics with complete cohesive failure of the adhesive were encountered on the NaOH treated surfaces that are comparable to the benchmark treatments such as anodization, which involve use of strong acids and multiple steps of treatment procedures. The NaOH treatment reported in this work is a very simple method with the use of a very dilute solution with simple ultrasonication being sufficient to produce durable joints. Graphical AbstractHighlights A very simple surface treatment method to achieve excellent and durable aluminum adhesive bonding. Our method involves simple immersion of aluminum in very dilute NaOH solution at room temperature with no involvement of strong acids or multiple procedures. Surface analysis via various surface characterization techniques showed morphological and chemical modifications favorable for obtaining highly durable bond strengths on the treated surface. Safe, economical, reproducible and simple method, easily applicable in industries.

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Section: Methodsmentioning

confidence: 53%

A simple surface treatment and characterization of AA 6061 aluminum alloy surface for adhesive bonding applications

Noormohammed

Sarkar

Paynter

et al. 2012

Applied Surface Science

Self Cite

145

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“…Guo et al [34] achieved superhydrophobic aluminium surfaces by roughening aluminium surface by immersing in sodium hydroxide solution and then treated with fluorinated silane. Saleema et al [35,36] Qian et al [40] prepared superhydrophobic aluminum surface using Beck's dislocation etchant and fluorination. Superhydrophobic aluminium surface was achieved by chemical etching with sodium hydroxide etchant followed by fluorosilane coating [41].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Mechanically Stable Superhydrophobic Aluminium Surface with Excellent Self-Cleaning and Anti-Fogging Properties

Varshney

Mohapatra

Kumar

2017

Preprint

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Development of the self-cleaning and anti-fogging superhydrophobic coating for aluminum surfaces which is durable in the aggressive conditions has raised tremendous interest in materials science.In this work, by employing chemical etching technique with mixture of hydrochloric and nitric acid, followed by passivation with lauric acid, superhydrophobic aluminum surface was synthesized. The surface morphology analysis reveals the presence of rough microstructures on coated aluminium surface.Superhydrophobicity with water contact angle of 170 ± 3.9° and sliding angle of 4 ± 0.5° is achieved.Surface bounces off the high speed water jet, indicating excellent water-repellent nature of coating. It is also continuously floated on water surface for several weeks, showing excellent buoyancy nature.Additionally, coating maintains its superhydrophobicity after undergoing 100 cycles of adhesive tape peeling test. Its superhydrophobic nature withstands 90° and 180° bending, and repeated folding and defolding. Coating exhibits the excellent self-cleaning property. In low temperature condensation test, almost no accumulation of water drops on the surface, showing the excellent anti-fogging property of coating. This approach can be applied to any size and shape of aluminium surface and hence has great industrial applications.

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“…This concept has been well elaborated by Neinhuis et al [4] on the surface of the lotus leaves which has been the classic example is the field of superhydrophobicity for researchers around the globe emphasizing the importance of the geometry and the chemistry of the surface. Inspired by this phenomenon, we have recently transformed aluminum surfaces, copper and silicon surfaces superhydrophobic by first creating surface roughness using methods such as chemical bath deposition, electrochemical methods and chemical etching methods and then modifying those surfaces by either passivating using low surface energy molecules such as stearic acid or fluoroalkyl-silane or by coating with rf-sputtered Teflon thin films [6][7][8][9][10][11]. The multilayer deposition process of organic and inorganic materials [12,13] such as nanoparticles as rough hydrophobic material [14,15] are also techniques to obtain superhydrophobic surfaces.…”

Section: Introductionmentioning

confidence: 99%

Fluorine Based Superhydrophobic Coatings

2012

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Superhydrophobic coatings, inspired by nature, are an emerging technology. These water repellent coatings can be used as solutions for corrosion, biofouling and even water and air drag reduction applications. In this work, synthesis of monodispersive silica nanoparticles of ~120 nm diameter has been realized via Stöber process and further functionalized using fluoroalkylsilane (FAS-17) molecules to incorporate the fluorinated groups with the silica nanoparticles in an ethanolic solution. The synthesized fluorinated silica nanoparticles have been spin coated on flat aluminum alloy, silicon and glass substrates. Functionalization of silica nanoparticles with fluorinated groups has been confirmed by Fourier Transform Infrared spectroscopy (FTIR) by showing the presence of C-F and Si-O-Si bonds. The water contact angles and surface roughness increase with the number of spin-coated thin films layers. The critical size of ~119 nm renders aluminum surface superhydrophobic with three layers of coating using as-prepared nanoparticle suspended solution. On the other hand, seven layers are required for a 50 vol.% diluted solution to achieve superhydrophobicity. In both the cases, water contact angles were more than 150°, contact angle hysteresis was less than 2° having a critical roughness value of ~0.700 µm. The fluorinated silica nanoparticle coated surfaces are also transparent and can be used as paint additives to obtain transparent coatings. OPEN ACCESSAppl. Sci. 2012, 2 454

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Chemical Nature of Superhydrophobic Aluminum Alloy Surfaces Produced via a One-Step Process Using Fluoroalkyl-Silane in a Base Medium

Cited by 211 publications

References 29 publications

A simple surface treatment and characterization of AA 6061 aluminum alloy surface for adhesive bonding applications

A simple surface treatment and characterization of AA 6061 aluminum alloy surface for adhesive bonding applications

Fabrication of Mechanically Stable Superhydrophobic Aluminium Surface with Excellent Self-Cleaning and Anti-Fogging Properties

Fluorine Based Superhydrophobic Coatings

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