The protection of the coating is mainly determined by the following two important factors:
1) The mechanical and chemical properties of the paint film itself.
2) The adhesion of the paint film, that is, the firm connection between the paint film and the surface of the object to be coated.
The first factor mentioned here actually depends on the physical and chemical properties of each component of the coating, such as the hardness, wear resistance, water resistance, weather resistance, corrosion resistance, and anti-external light of the coating. The second factor depends not only on the physical and chemical properties of the substrate to be coated and the surface treatment state before painting, but also on the adhesion between the substrate and the paint.
The physical properties of the adjusted metal refer to the fact that the metal surface always absorbs molecules, atoms and ions of other substances due to the relationship of atomic motion. This kind of adsorption often causes various changes on the metal surface, such as the adsorption of oxygen in the air, which will gradually transform into an oxide layer. In addition to oxygen, molecules, atoms and ions of other substances will be adsorbed, which will cause greater changes on the metal surface, and these changes will undoubtedly affect the relationship with the coating.
In terms of chemical properties, due to various reasons, there are pores and cracks on the surface of the substrate. Even after a good processing process (such as precision batching), when the metal surface is observed with a high-resolution microscope, it is still full of pores and substrates. There are many reasons for these pores and cracks, which may be formed by metal junctions; it may also be caused by the deformation of crystals that have been formed due to stress. Whatever the cause, these pores and cracks must play a subtle role in the relationship between the coating and the metal.
As for the adhesion between the paint and the surface of the substrate, it is actually a combination of the wet hole of the paint, the structure of the substrate itself, and the dirt on the metal surface. If the coating itself has poor wettability, or there are too deep pores on the metal surface, the removal material can only wet to the bulge, but not to the bottom of the valley, and the coating does not form continuous cracks, so the coating on the bulge will be easy Stripped and damaged. If there is oil stain on the metal surface, even a very slight oil stain will block the layer and the substrate. All of the above are the most influential factors, and they are also important factors for the coating to fail to exert its protective effect on the substrate. It can be seen from this that it is very important to do a good job of surface preparation before painting.
