1, the difference in meaning phosphating is a chemical and electrochemical reaction to form a phosphate chemical conversion film process, the phosphate conversion film formed is called phosphating film. Passivation refers to the process by which the metal is oxidized by a strong oxidizer or electrochemical method to make the surface become inactive or blunt, which is a method to convert the metal surface into a state that is not easy to be oxidized and delay the corrosion rate of the metal.
2, the difference in principle phosphating is a common pre-treatment technology, in principle belongs to the chemical conversion film treatment, applied to the surface of steel phosphating, non-ferrous metals (such as aluminum, zinc) can also be applied to phosphating. Passivation is due to the action of the corrosion products generated by the medium, if it has a dense structure, forms a film (often invisible), and is closely covered on the surface of the metal, it changes the surface state of the metal, so that the electrode potential of the metal greatly jumps in the positive direction, and becomes a blunt state of corrosion resistance.
3, the difference of the role of phosphating to provide protection to the base metal, to a certain extent to prevent metal corrosion; It is used for primer before painting to improve the adhesion and anti-corrosion ability of the paint film. It is used for antifriction lubrication in metal cold working process. Passivation plays the role of completely separating the metal from the corrosive medium; After passivation treatment, it has the characteristics of absolutely not increasing the thickness of the workpiece and changing the color, improving the precision and added value of the product, making the operation more convenient; Passivation promotes the formation of oxygen molecular structure passivation film on the metal surface, the film layer is dense, stable performance, and has a self-healing effect in the air.