Any decorative or functional coating is a covering applied to the surface of an object called the substrate. Being decorative, paints and lacquers are coatings that also have the function of protecting the substrate. Coatings are also applied to change or enhance the surface properties like adhesion, corrosion resistance, and wear resistance of the substrate. For most of the coating processes, an important consideration is the thickness control during application of coating. Coatings add properties like scratch resistance, glare reduction and UV protection levels to the acrylic and polycarbonate materials used as substrate.
Function of coating:-
Protective coatings main intention is to protect the metal surface from corrosion as well as obtain cosmetic finish for the substrate. Prevention of corrosion by the paint coating depend upon its anti- corrosive pigments adhesion properties. Paintings prevent the corrosion by preventing the cathodic and anodic reaction and preventing the electric current.
- Cathodic reaction is prevented by the paint coats by acting as an insulating material due to which oxygen and water movement to the substrate gets slowed down.
- Anodic reaction is prevented when anti-corrosive pigments forms a protective layer of various oxides by preventing the dissolving of various ions on the anodic area.
- Between the galvanic pairs, the paint coating of temaline epoxy has to form sufficient resistance to the current circuit to prevent the electric current.
In different environments, different types of coatings are used for providing protection. Any coating system includes a primer, intermediate and top coat. Between the corrosive environment like atmosphere, soil and water, and the steel substrate, the polymer film acts as a barrier. There are four main stages of a coating system.
- Abrasive blasting roughens and cleans the surface as well as prepares the surface for primer.
- Primers like epoxy zinc, inorganic zinc silicate wets the substrate which helps in creating a base for the intermediate coat.
- General epoxy polyamide intermediate provides building up of system thickness and also prevents permeability.
- Top coat adds finish to the substrate and also provide chemical resistance.
Coatings- protective covering is basically a paint or any other coating which gives aesthetic properties and protective properties to the substrate.