The working principle of metal powder spraying is almost the same as that of ordinary liquid coating electrostatic spraying, except that powder spraying is dispersed rather than atomized. It is a coating sprayed with an electrostatic powder spray gun, which disperses the powder particles while carrying a negative charge. Under the action of airflow and electrostatic attraction, charged powder particles are coated on the grounded coating, and then heated, melted, and solidified into a film. metal powder spraying is the dominant powder coating method in the industrial coating field.

Compared with spray painting, electrostatic metal powder spraying does not require diluents, is non-toxic, has no environmental pollution, has good coating quality, high adhesion and mechanical strength, is corrosion-resistant, has short curing time, does not require primer, has low technical requirements for workers, high powder recovery rate, and high usage rate, but its decorative properties are slightly worse than paint.

Spray paint is mixed with solvents (or hardeners), atomized by compressed air or electrostatic force, and then applied, flying onto the workpiece and adhering to it. The solvent evaporates (or reacts with each other) and solidifies into a film; The high content of VOC (volatile organic gas) poses greater harm to human health; The utilization rate of coatings is very low, only about 50%; The film thickness formed by one spray is 15-25um.

Metal powder spraying is in a fine powder state and adheres to the workpiece through electrostatic action. When passing through a high-temperature oven, the coating melts, flows flat, and crosslinks and cures; The VOC content is zero, but attention should be paid to the hazards of dust; Coatings can be recycled and utilized, with a utilization rate of over 99% during use; The curing time is shorter than that of spray painting, and there will be no frequent flow phenomenon in the spray painting area. Large equipment investment; Suitable for the coating of thick film coatings, with a spray film thickness of 50-150um.

After the metal surface coating is dried (cured), the metal surface is isolated from the environment. However, coatings cannot prevent or slow down the corrosion process, as polymers have a certain degree of permeability, with an average pore diameter of 10-5-10-7cm in their structure, while the diameters of water and oxygen molecules are usually only 10-6-10-8cm. To improve the impermeability of the coating, film-forming substances with low permeability and solid fillers with high shielding properties should be selected to achieve a certain thickness, uniformity, density, and no leakage of the coating.