In life, we will see a lot of products, all need to be painted, this is why!Probably because it can better protect their surface, steel structure is also the same, so how does steel structure paint play a role in corrosion protection?Let’s make up a small series of HJSD steel structure engineering to talk about it for us.

(1) Shielding effect

    The basic condition of electrochemical corrosion on steel surface is that there must be water, oxygen and ions on the surface of steel and the circulation of ions and electrons.Many coatings are chemically inert to acid, alkali, salt and other corrosive media, and have high dielectric constant to prevent the formation of corrosion circuit. After the metal surface is coated with paint film, the metal surface is separated from the environment to prevent water, oxygen and ions from reaching the steel surface through the coating, which plays a shielding role.For concrete, wood and masonry, shielding effect is purely mechanical isolation.

(2) Passivation and corrosion inhibition of pigments

    Pigment is an important part of coating. Antirust pigment interacts with metal surface to passivate or generate protective substances to improve the protective effect of coating.Antirust pigments with high activity, such as chromate and red lead, are often used in antirust primer. They have a certain passivation effect on metals. In addition, taking chromate system as an example, when a small amount of water passes through the paint film, a small amount of dissolved pigments will passivate the substrate.Therefore, corrosion inhibition can make up for the lack of shielding effect.On the other hand, the shielding effect can prevent the loss of inhibitor ions and make the corrosion inhibition stable and lasting. 

(3) Cathodic protection

　 If there are more active metal powder (metal with lower electrode potential) than steel in coating, such as zinc powder or aluminum powder, they can form sacrificial anode cathodic protection for steel. As long as the content of these active metal powder reaches the point contact degree between metal powder particles and metal powder and steel substrate, the steel can be protected from corrosion.Zinc rich coatings are typical of this kind of functional coatings.

    The above is how the steel structure paint plays a role in corrosion protection. We pay more attention to the quality and hope it can help you. If you want to know more about HJSD steel structure engineering, you can click the website page of HJSD steel structure engineering to browse!