Three Ways of Coating Corrosion Protection

Three ways of coating corrosion protection
There are three main ways for coatings to protect the object to be coated: shielding, passivation, and electrochemical.
Shielding and anticorrosion
The function of shielding is one of the basic characteristics of coatings, but shielding is also good or bad. Some coatings have strong shielding properties and can resist acids, alkalis, and solvents, and some coatings have weak shielding properties. Long-term immersion in water can also cause rust. , The difference is so big, the main reason is the different design principles for shielding.
Commonly used high-shielding paints, such as epoxy mica intermediate paint and epoxy glass flake paint, respectively use mica iron oxide and glass flakes as shielding media. The flake pigments form a structure with a labyrinth effect, which extends the penetration of corrosive media. Through the coating method, it can more effectively block the corrosive medium and achieve the purpose of anti-corrosion.
Passivation and anticorrosion
The principle of passivation can protect the substrate and isolate the corrosive medium. The mechanism of passivation is due to the action of metal and oxidizing substances, which forms a very thin, dense, good covering performance, and firmly adsorbed on the metal surface of the passivation film. It has the function of completely separating the metal from the corrosive medium, preventing the metal from contacting the corrosive medium, so that the metal basically stops dissolving, forming a passive state to achieve the effect of anti-corrosion.
Electrochemical corrosion protection
Electrochemical corrosion protection mainly uses the gain and loss electrons of active metals to protect iron. The common active metal is zinc. Zinc and iron contact, in the presence of corrosive media, a galvanic effect is formed. Zinc loses electrons while iron gains electrons. Iron gains electrons to avoid corrosion and is well protected. This kind of anti-corrosion mechanism is also called cathodic protection, that is, the principle of sacrificial anode to protect the cathode.
Zinc powder is one of the main anti-rust pigments. Common zinc powder coatings mainly include epoxy zinc-rich primer, inorganic zinc-rich primer and cold galvanized paint, etc., all of which use the cathodic protection of zinc to achieve the For anti-corrosion purposes, this type of coating is usually used in areas with high anti-corrosion requirements, and can better play its protective role.