Information about Wetting
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Wetting of different fluids. A shows a fluid with very high surface tension (and thus little wetting), while C shows a fluid with very low surface tension (more wetting action.) A has a high contact angle, and C has a small contact angle.
Wetting is the contact between a fluid and a surface, when the two are brought into contact. When a liquid has a high surface tension (strong internal bonds), it will form a droplet, whereas a liquid with low surface tension will spread out over a greater area (bonding to the surface). On the other hand, if a surface has a high surface energy (or surface tension), a drop will spread, or wet, the surface. If the surface has a low surface energy, a droplet will form. This phenomenon is a result of the minimization of interfacial energy. If the surface has a high energy, it will want to be covered with a liquid because this interface will lower its energy, and so on.
The primary measurement to determine wettability is a contact angle measurement. This measures the angle between the surface and the surface of a liquid droplet on the surface. For example, a droplet would have a high contact angle, but a liquid spread on the surface would have a small one. The contact angle
and the surface energies of the materials involved are related by the Young–Dupré equation
where
is the surface tension between two substances and S, V, and L correspond to the solid, vapor, and liquid substances in a contact angle experiment respectively.
A contact angle of 90° or greater generally characterizes a surface as not-wettable, and one less than 90° means that the surface is wettable. In the context of water, a wettable surface may also be termed hydrophilic and a non-wettable surface hydrophobic. Superhydrophobic surfaces have contact angles greater than 150°, showing almost no contact between the liquid drop and the surface. This is sometimes referred to as the "Lotus effect". This characteristic of spreading out over a greater area is sometimes called 'wetting action' when discussing solders and soldering.
Wetting is often an important factor in the bonding (adherence) of two materials. It is also the basis for capillary action, the ability of a narrow tube to draw a liquid, even against the force of gravity.
The shape of a drop is roughly a spherical cap.
See also
References
1. ^ T. S. Chow (1998). "Wetting of rough surfaces". 10 (27): L445. DOI:10.1088/0953-8984/10/27/001.
FLUID (Fast Light User Interface Designer) is a graphical editor that is used to produce FLTK source code. FLUID edits and saves its state in text .fl files, which can be edited in a text editor for finer control over display and behavior.
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Surface tension is an effect within the surface layer of a liquid that causes that layer to behave as an elastic sheet. It allows insects, such as the water strider (pond skater, UK), to walk on water.
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A chemical bond is the physical process responsible for the attractive interactions between atoms and molecules, and that which confers stability to diatomic and polyatomic chemical compounds.
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Surface energy quantifies the disruption of chemical bonds that occurs when a surface is created. In the physics of solids, surfaces must be intrinsically less energetically favourable than the bulk of a material; otherwise there would be a driving force for surfaces to be created,
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Surface tension is an effect within the surface layer of a liquid that causes that layer to behave as an elastic sheet. It allows insects, such as the water strider (pond skater, UK), to walk on water.
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contact angle is the angle at which a liquid/vapor interface meets the solid surface. The contact angle is specific for any given system and is determined by the interactions across the three interfaces.
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Hydrophile, from the Greek (hydros) "water" and φιλια (philia) "friendship," refers to a physical property of a molecule that can transiently bond with water (H2O) through hydrogen bonding.
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hydrophobicity (from the combining form of water in Attic Greek hydro- and for fear phobos) refers to the physical property of a molecule (known as a hydrophobe) that is repelled from a mass of water [1].
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lotus effect in material science is the observed self-cleaning property found with lotus plants. In some Eastern cultures, the lotus plant is a symbol of purity. Although lotuses prefer to grow in muddy rivers and lakes, the leaves and flowers remain clean.
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A solder is a fusible metal alloy, with a melting point or melting range of 180 to 190 °C (360 to 370 °F), which is melted to join metallic surfaces, especially in the fields of electronics and plumbing, in a process called soldering.
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Soldering is the process in which two metals are joined together by means of a third metal or alloy having a relatively low melting point. Soft soldering is characterized by the value of the melting point of the third metal or alloy, which is below 400°C.
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Adhesion is the molecular attraction exerted between bodies in contact.
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Mechanisms of Adhesion
Five mechanisms have been proposed to explain why one material sticks to another:Mechanical Adhesion
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Capillary action, capillarity, capillary motion, or wicking is the ability of a substance to draw another substance into it. The standard reference is to a tube in plants but can be seen readily with porous paper.
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Tube may refer to:
Object
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Object
- cathode ray tube, a common component of electronics such as televisions and other displays
- cylinder (geometry), a hollow shape
- inner tube, a component of vehicular tires
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In geometry, a spherical cap is a portion of a sphere cut off by a plane. If the plane passes through the center of the sphere, so that the height of the cap is equal to the radius of the sphere, the spherical cap is called a hemisphere.
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In fluid mechanics, dewetting is one of the processes that can occur at a solid-liquid or liquid-liquid interface. Generally, dewetting describes the rupture of a thin liquid film on the substrate (either a liquid itself, or a solid) and the formation of droplets.
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The sessile drop technique is a test performed to determine the chemical affinity that a liquid has to a solid. The test is usually done to either examine the physical properties of the liquid against different solid surfaces or the properties of a solid surface against different
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Anti-fog agents, also known as anti-fogging agents and treatments, prevent the condensation of water on a surface in the form of small droplets which resemble fog. Anti-fog treatments are often used for transparent glass or plastic surfaces in optics, such as the lenses and
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digital object identifier (or DOI) is a permanent identifier given to a document, which is not related to its current location. A typical use of a DOI is to give a scientific paper or article a unique identifying number that can be used by anyone to locate details of the paper, and
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