Hydrophobic properties of a wavy rough substrate

Carbone, Giuseppe; Mangialardi, L.

doi:10.1140/epje/e2005-00008-y

Cited by 96 publications

(114 citation statements)

References 21 publications

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“…64,[66][67][68] An energy barrier unfavorable to liquid wicking may be maximized in this manner. 59,[69][70][71][72][73] This energetic barrier, if it is larger than the inherent thermal energy 7 needs to be overcome by mechanical means such as vibrations, 74,75 impact 76,77 or load imposed on the drop.…”

Section: Defining Superhydrophobicity and Superhydrophilicitymentioning

confidence: 99%

Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

Drelich

Marmur

2014

Surface Innovations

154

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The terms superhydrophobicity and superhydrophilicity were introduced not very long ago, in 1996 and 2000, respectively.The former is used to describe exceptionally weak and the latter used to indicate strong interactions of materials and IntroductionAfter more than two centuries of research, capillarity and wetting phenomena still remain popular topics of investigation in many modern surface chemistry laboratories. Curiosity and fascination with rain droplets splashing in a puddle, water droplets decorating flowers, leaves of plants and fruits after rain or watering and colorful soap bubbles shaped at the end of wheat straw have never been stronger and go beyond scientific laboratories. Colorful images of liquid droplets and puddles, illustrating their behavior on a variety of surfaces, thrive in professional journals, popular magazines and Internet. However, terms such as wetting, spreading and contact angle are still puzzling to the layman and beginner researcher. To facilitate

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Section: Defining Superhydrophobicity and Superhydrophilicitymentioning

confidence: 99%

Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

Drelich

Marmur

2014

Surface Innovations

154

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“…For a micro-or nanostructured substrate, usually the droplet stays in the Cassie state, but the Cassie state can switch (irreversibly) to the Wenzel state when the droplet is pressed against the substrate [23]. The Wenzel droplets are PRL 97,…”

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confidence: 99%

“…The contact angle is given by cos 0 ÿ1 1 cos Cassie model: (2) Quere states that there exists a critical contact angle c such that the Cassie state is favored when is larger than c [22]. For a micro-or nanostructured substrate, usually the droplet stays in the Cassie state, but the Cassie state can switch (irreversibly) to the Wenzel state when the droplet is pressed against the substrate [23]. The Wenzel droplets are highly pinned, and the transition from the Cassie to the Wenzel state results in the loss of the antiadhesive properties generally associated with superhydrophobicity.…”

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confidence: 99%

Influence of Surface Roughness on Superhydrophobicity

2006

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Superhydrophobic surfaces, with a liquid contact angle greater than 150 , have important practical applications ranging from self-cleaning window glasses, paints, and fabrics to low-friction surfaces. Many biological surfaces, such as the lotus leaf, have a hierarchically structured surface roughness which is optimized for superhydrophobicity through natural selection. Here we present a molecular dynamics study of liquid droplets in contact with self-affine fractal surfaces. Our results indicate that the contact angle for nanodroplets depends strongly on the root-mean-square surface roughness amplitude but is nearly independent of the fractal dimension D f of the surface. DOI: 10.1103/PhysRevLett.97.116103 PACS numbers: 68.08.BcThe fascinating water repellents of many biological surfaces, in particular, plant leaves, have recently attracted great interest for fundamental research as well as practical applications [1][2][3][4][5][6][7][8]. The ability of these surfaces to make water bead off completely and thereby wash off contamination very effectively has been termed the lotus effect, although it is observed not only on the leaves of the lotus plant but also on many other plants such as strawberry, raspberry, and so on. Water repellents are very important in many industrial and biological processes, such as the prevention of the adhesion of snow, rain drops, and fog to antennas, self-cleaning windows and traffic indicators, low-friction surfaces, and cell mobility [9][10][11].Most leaves that exhibit strong hydrophobicity have hierarchical surface roughness with micro-and nanostructures made of unwettable wax crystals. The roughness enhances the hydrophobic behavior, so that the water droplets on top tend to become nearly spherical. As a result, the leaves have also a self-cleaning property: The rain drops roll away, removing the contamination particles from the surface, thanks to the small adhesion energy and the small contact area between the contaminant and the rough leaf [1].The hydrophobicity of solid surfaces is determined by both the chemical composition and the geometrical microor nanostructure of the surface [12 -14]. Understanding the wetting of corrugated and porous surfaces is a problem of long-standing interest in areas ranging from textile science [15] to catalytic reaction engineering [16]. Renewed interest in this problem has been generated by the discoveries of surfaces with small scale corrugations that exhibit very large contact angles for water and other liquids -in some cases, the contact angle is close to 180 . Such surfaces are referred to as superhydrophobic [17].The contact angle between a flat solid surface and a liquid droplet depends on the relation between the interfacial free energies per unit area: solid-liquid sl , solidvapor sv , and liquid-vapor lv . The Young equation sl lv cos sv results from the minimization of the total free energy of the system on a flat substrate surface. Complete wetting corresponds to 0 and typically happens on solids with a high surface energy sv . L...

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“…The wetting by a liquid of a rough solid surface, such as the mold cavity, depends, among other factors, upon the liquid-gas surface tension and the contact angle of the liquid over a flat surface of the same solid substrate [36]. The smaller wettability of colder molten metal may possibly arise from an increase in wetting angle, leading to a change from the Cassie to Wenzel wetting mechanism [37,38]. According to the Thomas Young wetting model, a larger liquid-solid contact angle can be due to an increase in liquid-gas surface tension γLG from its value at the liquid state (552-572 mN m −1 for molten magnesium [39].…”

Section: Discussionmentioning

confidence: 99%

Investigating surface roughness of ZE41 magnesium alloy cast by low-pressure sand casting process

Sanitas

Coniglio

Bedel

et al. 2017

Int J Adv Manuf Technol

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To cite this version:A. Sanitas, N. Coniglio, M. Bedel, M. El Mansori. Investigating surface roughness of ZE41 magnesium alloy cast by low-pressure sand casting process. International Journal of Advanced Manufacturing Technology, Springer Verlag, 2017, 92 (5-8), pp.1883-1891. 10.1007 Investigating surface roughness of ZE41 magnesium alloy cast by low-pressure sand casting processAbstract The sand mold 3D printing technologies enable the manufacturing of molds with great dimensional accuracy. However, the roughness of as-cast components is higher when cast in a 3D printed mold rather than in a traditional sand mold. Coating the inner cavity is an efficient solution but can be costly and, in the narrowest cavities, not achievable. Finding a procedure to reduce the as-cast roughness without coating would ease the casting procedures. In the present work, surface analysis of ZE41 magnesium alloy is presented after being cast in 3D printed furan sand molds without coating using the low-pressure casting process. The molten metal temperature was measured during casting at different positions along the cast cavity. The as-cast surface roughness was correlated to the molten metal temperature and solid fraction at the time of contact against the sand mold surface.

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Hydrophobic properties of a wavy rough substrate

Cited by 96 publications

References 21 publications

Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

Physics and applications of superhydrophobic and superhydrophilic surfaces and coatings

Influence of Surface Roughness on Superhydrophobicity

Investigating surface roughness of ZE41 magnesium alloy cast by low-pressure sand casting process

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