Anticorrosion mechanisms include several

       Anticorrosion mechanisms include several



The above-mentioned anti-corrosion effects of anti-rust pigments usually exist at the same time, and its anti-corrosion mechanism includes the following three aspects: physical, chemical and electrochemical. ①Physical anticorrosion effect. Appropriately matched with pigments that react with oily film-forming agents, a dense anti-corrosion coating can be obtained to enhance the physical anti-corrosion effect. For example, lead-containing pigments react with oil to form lead soap to make the anti-corrosion coating dense, thereby reducing the penetration of water and oxygen harmful substances. Phosphate pigments are hydrolyzed to form insoluble basic acid salts, which have the effect of blocking pinholes in anti-corrosion coatings. Iron oxides or scaly mica powder, aluminum powder, glass flakes and other pigment fillers can reduce the permeability of the anti-corrosion coating and play a physical anti-corrosion effect.

② chemical antiseptic effect. When harmful acidic and alkaline substances penetrate into the anti-corrosion coating, they can neutralize and change them into harmless substances, which is also an effective anti-corrosion method. In particular, the clever use of amphoteric compounds such as zinc oxide, aluminum hydroxide, and barium hydroxide can easily neutralize acidic or alkaline harmful substances and play a role in anticorrosion, or can react with water and acid to generate alkaline substances. These alkaline substances are adsorbed on the surface of the steel to keep the surface alkaline, and the steel is not easy to rust in an alkaline environment.

③Electrochemical anticorrosion. When moisture and oxygen infiltrated from the pinholes of the coating pass through the anti-corrosion coating, they react with the anti-rust pigment dispersed in the anti-corrosion coating to form anti-corrosion ions. This moisture containing anti-corrosion ions reaches the metal surface, passivates the steel surface (raises the potential), and prevents the dissolution of iron ions, which is the characteristic of chromate pigments. Or use a metal with a lower electrode potential than steel to protect steel. For example, zinc-rich paint is because the electrode potential of zinc is lower than that of steel, which acts as a sacrificial anode, so that steel is not easily corroded.