The corrosion of the painted metal is highly dependent on the corrosion resistance of the metal material itself. The metal used for painting is steel, aluminum alloy, copper alloy or magnesium alloy. It is undoubtedly different in metal materials, and the anti-corrosion function of metal spray paint is not the same. The difference in the appearance of metal materials is significantly different by the anti-corrosion and anti-corrosion protection of the coating after painting. For example, the steel plate parts treated by sand blasting and the same grade steel plate parts that are naturally rusted are protected by the same type of paint coating. Because of the rusting argon gas, the corrosion rate of natural rusted steel plate parts is higher than that of the blasted steel plate parts. The corrosion protection effect is significantly lower than the latter. Defects in metal appearance such as noisy, microcracking, stress, etc., and the adsorption of atmospheric moisture and reactive ions (Cl-, Br-, etc.) will affect or even accelerate the corrosion of paint-coated metals to varying degrees.

The anti-corrosion and anti-corrosion function of the paint-coated metal can be effectively improved by the pre-treatment and the external treatment process before the metal surface painting and painting. The production practice proves that the corrosion resistance of the painted metal coating has a great influence on the quality of the pre-treatment of the substrate before painting. The metal (especially the casting) is effectively degreased, derusted or sprayed before being painted on the exterior. Sand blasting, etc. can cause purification and activation of the exterior, ensuring excellent adhesion of the coating paint film to the base metal, which is very advantageous for improving the corrosion resistance of the painted metal.

The phosphating treatment of the pre-treatment process of steel material coating processing is widely used as the bottom layer of paint coating, which is unobjectionable for improving the adhesion of the coating layer and improving the anti-corrosion and anti-corrosion function of the coated metal. The phosphating, chemical oxidation and anodizing treatment of aluminum alloy can be used as the bottom layer of the paint coating, which is undoubtedly excellent for improving and improving the corrosion resistance of the coated metal. In summary, the outstanding surface treatment process for metal substrates is an important part and a reliable foundation for improving the corrosion resistance of paint-coated metals.