The main function of the anti-rust pigment is to prevent metal corrosion and improve the protective effect of the paint film on the surface of the gold bend. The functions of anti-rust pigments can be divided into two categories: physical anti-rust and chemical anti-rust, and chemical anti-rust pigments can be further divided into two types: corrosion inhibition type and electrochemical action type.
The physical anti-rust pigment fills the paint film structure with its fine and dense particles, improves the compactness of the paint film, plays a shielding role, reduces the permeability of the paint film, and thus plays an anti-rust effect. Commonly used such as iron oxide red. Pigments with a flake structure, such as aluminum powder and glass flakes, can form thin flakes in the paint film, which increases the sealability of the paint film and improves the anti-aging performance of the paint film.
Anti-rust pigments with chemical corrosion inhibition rely on chemical reactions to change the properties of the surface or the characteristics of the reaction products to achieve the purpose of anti-rust. Antirust pigments with chemical corrosion inhibition can interact with metal surfaces, such as passivation and phosphating, to produce new surface films, such as passivation film and phosphating film. The electrode potential of these films is more positive than that of the original metal, so that the metal surface partially or completely avoids the possibility of becoming an anode; in addition, there are many micropores on the film, which facilitates the adhesion of the paint film. Anti-rust pigments can also chemically react with the ingredients in some paints to form stable,
A compound with good water resistance and low permeability. Some pigments form corrosion-inhibiting complexes during the film-forming process, which improves the anti-rust effect, and generally cannot be used underwater, otherwise they are prone to foaming. Commonly used chemical corrosion-inhibiting pigments include lead-based pigments, chromate pigments, phosphate pigments, etc.
Zinc powder is the most important anti-rust pigment that plays an electrochemical role. The main raw material for making zinc powder is zinc ingot with a purity of 99.5%. The manufacturing methods of zinc powder include atomization method and steaming method. Zinc-rich paint is currently the most common and important anti-rust primer in atmospheric environment and marine engineering. Only in acidic environment, the corrosive medium is easy to generate hydrogen with zinc powder, and other coatings are used. Zinc-rich paint with zinc powder as the pigment forms a conductive protective coating on the steel surface. The chemical reaction of zinc forms zinc salts and zinc complexes on the surface of the coating. These products are extremely insoluble and stable compounds and are deposited on the surface of the coating to prevent the erosion of oxygen, water and salts, thereby causing corrosion. To the anti-rust effect, so that the steel is protected.
