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Main influencing factors of anti-corrosion coatings.
Source: | Author:佚名 | Published time: 2021-07-05 | 520 Views | Share:
The film-forming material of anti-corrosion coating has chemical stability in corrosive medium, and its standard is related to the composition and chemical structure of film-forming material. It mainly depends on whether it is easy to react with corrosive medium or decompose into small molecules in the medium under dry film conditions.

The film-forming material of anti-corrosion coating has chemical stability in corrosive medium, and its standard is related to the composition and chemical structure of film-forming material. It mainly depends on whether it is easy to react with corrosive medium or decompose into small molecules in the medium under dry film conditions.

The shielding effect of anti-corrosion coating is very important, whether from the perspective of electrochemical corrosion prevention or simple isolation, and the shielding performance of paint film depends on the structure of film-forming material, pores and coating pinholes. The penetration rates of water, oxygen and ions are different. The transmission velocity of water is much higher than that of ions. The permeability of oxygen is complex and has a great relationship with temperature. Water and oxygen can form corrosive electricity on the metal surface after passing through the paint film. Ions penetrate the paint film less, and their direct effect on the substrate metal can be ignored, but it will increase the conductivity of the paint film.

When the molecules in the film structure have more functional groups, the structural pores of the emulsion paint film are less, and can react with each other in the film-forming process to form a network three-dimensional structure with high cross-linking density, so as to enhance the corrosion resistance of the coating. The physical and mechanical properties of paint film greatly affect the anti-corrosion effect of anti-corrosion coatings. They are related to the molecular weight, chain links, side genes and so on. The influence of pigments and fillers plays a coloring role in the paint, while physical pigments are used to adjust the mechanical properties of the paint film or the fluidity of the paint. For anti-corrosion coatings, in addition to the above two pigments, there are also pigments for the purpose of anti-corrosion: one is antirust pigments that use their chemical properties to inhibit metal corrosion; The other is flake pigment, which improves the shielding of the coating through physical action. Antirust pigments can be divided into alkaline pigments, soluble pigments and metal powder pigments.

Alkaline pigments react with oily film-forming substances to produce metal soaps, such as red lead, lead monooxide, lead cyanamide, basic lead chromate, calcium lead carbonate and basic lead sulfate. When metal soap is in contact with water, its decomposition products can inhibit corrosion. In addition, when metal soap is generated, the paint film improves the shielding effect on the environment. Alkaline pigment keeps the interface between paint film and metal slightly alkaline and also plays an anti-corrosion role. Soluble pigment, perchloroethylene paint, usually chromate pigment. These pigments dissolve chromate ions in contact with water. Chromate ion has strong oxidation, which can passivate the metal surface and play an anti-corrosion role.


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