Rust prevention mechanism of VCI
In the microenvironment of the packaging material and the packaged object, the gas molecules released by the VCI rust inhibitor can chemically react with the oxygen and water in the packaging space to form inert substances, which are adsorbed on the metal surface to form a thin protective film.
So as to block the further contact of the metal with the outside oxygen and water, so as to prevent the metal from electrochemical corrosion and chemical corrosion.
VCI materials mainly play an anti-corrosion effect from the following three aspects:
1) Anode passivation is formed on the metal surface to isolate or slow down the electrochemical process of the cathode. The chemical groups with anode passivation include nitrogen dioxide and hydroxide ions.
2) Use the hydrophobic film formed by the adsorption of organic cation groups on the metal surface to shield the effect of the rusting medium and reduce the electrochemical activity of the metal to be protected.
3) The volatilized gas molecules react with the metal to form a stable complex film on the surface of the metal to be protected, which increases the resistance of the metal surface and blocks the electrochemical activity, thereby protecting the metal, such as benzophenone. Letrozole and so on.
Generally, the anti-rust effect is often produced by the combined effect of several factors, and the vapor phase corrosion inhibitor will have the anti-rust effect after it reaches the metal surface.
The distance between the metal and the anti-rust material should be controlled below 40 mm to ensure the gas concentration of the corrosion inhibitor in a relatively closed microenvironment.
The anti-rust mechanism process is shown in Figure.
After the vapor phase corrosion-inhibiting gas molecules of VCI anti-corrosion packaging materials diffuse, they adhere to the metal surface to form a protective film that cuts off the electron displacement channel from the anode to the cathode, insulates the metal from rusting, and keeps the metal bright as new.
Quote-[1] Chen Qun. Research on the application of VCI plastic anti-rust film in cold-rolled steel coil packaging [J]. Mechanical Engineer, 20105,000 (004): 171-171,172
