Definition - What does Surfactant mean?

A surfactant is a chemical substance that is added to a material's surface (often metal) to reduce the surface tension experienced on the surface when it comes in contact with other fluids. The use of surfactants increases the wetting and dispersion of corrosion preventative coats and linings.

Corrosionpedia explains Surfactant

Surfactants perform efficiently by reducing the surface tension of a solvent (such as water). Surface tension is the force that causes the molecules on the surface of a liquid to be pushed together and form a layer. The tension of a liquid's surface film is caused by the attraction of the particles in the surface layer by the bulk of the liquid, which tends to minimize the surface area.

Increased surface tension is a known cause of pitting corrosion. Therefore, in regards to surfactants, the key vital action of corrosion inhibition is the adsorption of the surfactant's functional group onto the material's surface. Surfactant molecule absorption is generally related to its ability to aggregate.

In various applications surfactants are mixed with builders or pH boosters (such as carbonates, phosphates and silicates) and suitable solvents (such as alcohols or hydrocarbons) to increase efficiency.

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