After the metal is treated by oxidizing medium, the corrosion rate of the metal is significantly lower than that of the original untreated metal, which is called passivation of the metal.
Generally speaking, passivation actually turns the active metal surface into an inert surface through the chemical reaction of passivation solution, so as to prevent the external destructive substances from reacting with the metal surface and achieve the purpose of prolonging the metal rusting time. (That’s why the product is easy to rust before passivation, but not after passivation. For example, iron will soon dissolve in dilute nitric acid, but the phenomenon of dissolving in concentrated nitric acid almost completely stops; Aluminum is unstable in dilute nitric acid, but aluminum containers can be used to store concentrated nitric acid. These passivation phenomena are called chemical passivation.
Principle of passivation
The principle of passivation can be explained by the thin film theory, that is, it is considered that passivation is due to the interaction between metal and oxidizing medium, which will produce a very thin (about 1nm), dense, well-covered passivation film on the metal surface, which can be firmly attached to the metal surface. This film exists as an independent phase, usually a compound of oxygen and metal.
It can completely separate the metal from the corrosive medium, and prevent the metal from directly contacting with the corrosive medium, so that the metal basically stops dissolving and forms a passive state to achieve the purpose of preventing corrosion and rust.
Characteristics and advantages of passivation:
Stainless steel passivation solution does not change the size, color and appearance of screws; There is no attached oil film, and the corrosion resistance is better and more stable (passivation treatment is the best choice to replace traditional anti-corrosion treatment to soak anti-rust oil). There is no need for special equipment and strict processing conditions, only a few plastic containers or stainless steel tanks are required, and the cost is low (2/3 less than that of outsourcing processing); The operation is simple, which greatly meets the needs of enterprises, and ensures that everyone can do it, everyone can do it, and can do it at any time. Just immerse the screws in Senyuan brand stainless steel passivation solution for 30 minutes at room temperature.
Passivation:
After the screw is passivated, a very dense passivation film with good coverage will be formed on the surface of the screw, which can make the screw more corrosion-resistant, up to more than 500 hours of salt spray test.
Screw passivation process:
First degrease the screws-rinse them with flowing water-activate them-rinse them with flowing water-passivate them (for more than 30 minutes)-rinse them with flowing water-rinse them with ultrapure water-dry them and pack them.
Post time: Nov-29-2022