Protective coatings have been used in many forms since civilization came to play. From the very first cave drawings then to the Chinese artifacts and Greek statues, coatings were being used for protective and decorative motives. Today many engineered products have been coated to be guarded against working environments and usage.
Protective coatings can be applied using many methods and may be used for various other reasons than just corrosion prevention. Every organic form of barrier protection is permissive to some level, and once a protective coating is being penetrated, the corrosion resistance will get compromised. Most powders and paints are porous and can be easily damaged, letting electrolytes (humidity, moisture) to get to the underlying steel. If constant maintenance isn’t performed, under-film corrosion starts and the coating could fail in a brief period. No cathodic protection is provided by powder and paint coatings, which restricts their time of first maintenance to nine years or less in some environments. Protective coatings, like powder and paint coatings, applied to an iron provide barrier protection. As barrier protection is based on the integrity of the coating, the application, selection, and handling of powder and painted coated materials is essential. It is imperative that these coatings are carefully handled during installation and if destroyed are fixed to ensure they last long as planned. Both powder and paint coatings could be utilized in conjunction with the duplex system, otherwise referred to as hot-dip galvanizing. Both coatings work in synergy providing superior corrosion protection while letting the specified coat to suit the aesthetic preference. The protective coating is the layer of a material applied to a surface of a different material with the aim of preventing or inhibiting corrosion.
A zinc coating on steel is an excellent example of the reactive protective coating. The zinc works with the atmosphere even more readily compared to the steel, therefore preventing the oxidation of that steel. The protective coating could be sprayed on, painted on, plated on and even welded to the material. Polymer coatings are usually sprayed on. Zinc coatings are usually applied by the hot dipping or electroplating method. Coating is not limited to prevention of corrosion. A protective coating could also be used in increasing the aesthetic appeal and wear resistance of a material. A protective coating could provide electrical properties or water resistance which the material didn’t have before a protective coating being applied.
TYPES & PROPERTIES OF COATINGS
A protective coating could be non-metallic or metallic. Materials that are frequently used in protective coating are polymers, polyurethanes, and epoxy resin. Materials that are used for metallic protective coatings are zinc, chromium, and aluminum. There two major classes of coatings: Inorganic and organic. Although, both may have similar functions in the coatings system. Organic coatings comprise of carbon and are gotten from animal oil or vegetable. These days, most of these type of coating come from modified and refined petroleum products. Organic coatings include resins, paints, varnishes, and lacquers. Inorganic coatings include glass linings, porcelain enamels, and metallic coatings. Metallic coatings can be produced with some techniques such as electroplating, hot dipping, thermal spray, cladding, and other methods.