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This post was last edited by Wang Wei2 on 2020-5-28 at 12:10. We know that there are many types of protective coatings, each with different properties; the objects to be protected vary, and the conditions under which they are used also differ. In short, there is no \"single type of coating\" that can solve the corrosion problems of all metals. Therefore, choosing the paint is very important. Therefore, an excellent anti-corrosion coating must possess the following characteristics: 1. Good corrosion resistance. The corrosion resistance of a coating refers to the fact that its cured coating remains stable in terms of both physical and chemical properties when in contact with corrosive agents such as water, acids, alkalis, salts, various chemicals, waste liquids, and industrial gases. In other words, it is not swollen or dissolved by these corrosive agents, nor is it damaged or decomposed by them, and it does not undergo any harmful chemical reactions with them. 2. Air permeability and water permeability should be low. Coatings generally have a certain degree of air and water permeability; therefore, it is necessary to use film-forming materials with low air permeability and coatings that provide strong shielding effects. 3. It must have good adhesion and sufficient mechanical strength. Whether the coating can adhere firmly to the metal substrate is one of the key factors determining its ability to provide corrosion protection ； In addition, the cured coating should also possess certain physical and mechanical strength to withstand the stresses under operating conditions. 4. Low coating costs and painting expenses. Under normal circumstances, the cost of protection through painting is lower than that of other protection methods. The construction costs are higher than the cost of the paint itself. In short, in practice it often happens that a particular type of coating has excellent corrosion resistance, but its adhesion to the substrate and mechanical properties are poor, rendering it unusable. To resolve the conflict between corrosion resistance and mechanical properties, a combination of several coatings is often used.