Coating is a kind of mixed material, which is composed of resin, pigment, filler, curing agent, auxiliary solvent and so on. They are applied thinly, measured in microns, to the surface of an object. They react with curing agent or water vapor, oxygen, etc. through solvent volatilization, dry and solidify to form an insoluble film, firmly adhere to the surface of the substrate to provide anti-corrosion protection, and can also provide beautiful colors in appearance.
Chemically, paint film aging refers to the gradual degradation of chain or network structure macromolecules of organic paint films into small molecules. The causes include heat, light, mechanical action, the action of oxidants or atmospheric oxygen, and the action of water, acid, and alkali, which lead to the decomposition of the film.
The degradation of the film quality of the coating during use is a normal aging process. Coating defects occur when a coating system develops defects much faster than expected service life, or causes premature rusting of steel structures. Coating defects can occur for many reasons and may be a combination of one or more factors:
1. Improper or wrong formulation
2. Improper or wrong coating support system design
3. Poor surface treatment
4. Poor construction quality
5. The application environment of the coating exceeds its own performance limit
6. The effect of external machinery, impact force and mechanical wear, etc.
