What Exactly does Anticorrosive Coating Do?
The anti-corrosion coating can protect the steel and play an anti-corrosive role. People generally agree because of the following three effects:
Shielding effect: The shielding effect of the paint film layer is to isolate the direct contact between the protected substrate and the corrosive medium. If the metal surface is prevented from being corroded, the paint film layer must be required to prevent the external environment from contacting the metal surface to achieve the anticorrosive effect. For example, ZS-1021 closed coating can effectively shield corrosive media, air, acid rain. It can protect the substrate corrosion and rust.
Sacrifice anode protection: In consideration of electrochemical corrosion, add some more active metal powder (electrode potential is higher than the protected medium) in the coating, such as zinc powder as filler. When electrochemical corrosion occurs on the protected metal surface, the metal in the highly active ZS-711 inorganic anticorrosive coating is dissolved as a sacrificial anode, with a temperature resistance of up to 400 ° C, which prevents the base metal from being corroded. For example, when forming a battery reaction, Zn decomposes into Zn2 at the anode, reacts with OH- generated at the cathode to form Zn (OH) 2 and Zn (OH) 2 reacts with CO2 to form ZnCO3. Protect steel from corrosion, 711 inorganic anticorrosive coating is used in seawater, the service life can reach 50 years.
Corrosion inhibition and passivation: With the help of the anti-rust pigment contained in the coating, the corrosion inhibition ions are dissociated in the solution to passivate the substrate surface and inhibit the corrosion process. For example, ZS-1034 acid and alkali resistant anticorrosive paint, advanced nano antirust pigments react well with corrosive media to form a passivation film of Weihua anticorrosive paint. When the oxygen concentration on the metal surface exceeds a certain amount, the Fee generated by the oxidation reaction on the metal surface can be decidified to Fe3. Then Fe3 reacts with the OH-reaction resulting from the reduction reaction on the metal surface to form Fe (OH) 3 precipitation and deposit. The formation of a dense layer on the metal surface prevents further corrosion, which is called passivation. The concentration of OZ that can cause passivation is called the critical concentration. The higher the pH value, the lower the critical concentration. Therefore, high pH is beneficial to passivation. When the pH value is lower than 10, it is difficult to increase the metal surface concentration to a critical concentration, but it is possible to use an oxidant having a concentration exceeding a certain amount and having a certain water solubility, such as rust preventive pigments chromate, lead salt, phosphate.
Metal anti-corrosion coating thickness detection
LS221 paint thickness gauge measure the anti-corrosion paint
In the metal coating process, the detection of the coating thickness on the metal surface is also an extremely important step. The coating thickness is an important indicator of whether the anticorrosive coating works. Measuring the thickness of a coating with an anti-corrosion paint measuring gauge is one of the most important quality inspection indicators of an anti-corrosion coating. Linshang LS221 paint measuring gauge uses magnetic thickness measurement method and eddy current thickness measurement method, which can be used to measure the thickness of non-magnetic coating on the surface of magnetic substrate. It can also be used to measure the thickness of non-conductive coatings on non-magnetic metal surfaces. The Linshang paint measuring gauge adopts a separate design, which is very suitable for using in the narrow space. It is very convenient to view the data while measuring in complex environments. This instrument has the characteristics of fast response speed, high measurement accuracy, stable zero position without drift and durability. The coating thickness measurement is simple and convenient whether indoors or outdoors.
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