- Barrier – to protect metal against water, oxygen and electrolyte that can come into contact with the underlying metal
- Inhibitive – contains chemicals that inhibit corrosion
- Sacrificial – provide galvanic protection
- Combination – of various processes to achieve more benefits
Components of Protective coating systems
Protective coating systems are usually composed of a combination of coatings applied in a predetermined interval with enough time in between to allow for drying. The types of coatings that will be used are chosen carefully to achieve the required physical performance and aesthetic characteristics required from the coating system. The typical coating system consists of the primer, intermediate coating and finish coating that provide specific benefits. The primer enhances adhesion and provides corrosion and stain resistance while the intermediate coat provides the barrier and film build. The finish coat provides resistance to chemicals and different weather elements as well as the necessary appearance of the steel part.
Examples of Protective coating systems
Among the different types of Protective coating systems, powder coating is typically used for applications that require impact resistance and aesthetic qualities. Powder coating involves the application of dry powder instead of the conventional liquid paint. While powder coating is more expensive than liquid paint, it provides the advantages of being environmentally friendly because it does not emit any volatile organic compounds (VOCs) which are found in solvents used in liquid paint. Powder coating also provides the advantages of a high quality surface finish that increases the value of metal products. The coated surface becomes resistant to heat, corrosion, abrasion, chemicals, UV rays, and exposure to moisture.
Two-component epoxy coating
There are tons of protective coatings available in the market but for critical industrial applications, one of the best options is two-component epoxy coating. This type of coating system has been developed for heavy duty applications on metals like steel and iron. The epoxy used is called two-part because it is composed of a primer and a finish that is designed for metal protection against oxidation and corrosion. The epoxy finish is extremely hard and resistant to friction, turbulence, corrosive fluids, particle abrasion, heat and cold and impact forces. However, heat exposure can cause the epoxy coatings to deteriorate faster.
Hot dip galvanizing
In the galvanizing process of steel, zinc is used as protective coating against corrosion. The zinc coating acts as the sacrificial anode that will corrode instead of the underlying metal. Corrosion will provide the electrons that will reverse the corrosion cells and transform the anodes into cathodes. Galvanized steel products can last for decades and promises longevity even in salt water applications and caustic environments. It is also completely recyclable which makes it an environmentally friendly Protective coating system.