Introduction About Corrosion Inhibitors
The Definition And Basic Description of Corrosion Inhibitor
Corrosion inhibitor is a chemical substance or a mixture of several chemical substances that exists in the environment in an appropriate concentration and form that can prevent or slow down corrosion. Corrosion inhibitor technology is widely used in the production and processing of petroleum products, chemical cleaning, atmospheric environment, industrial water, instrument manufacturing and other production processes due to its advantages of simple operation, quick effect and protection of the entire system.
Types of Corrosion Inhibitors
Classified by Mechanism of Action
Mixed type corrosion inhibitor. It can slow down the reaction rate of the cathode and anode at the same time, mostly caused by adsorption at the anode and cathode, sometimes also called masking corrosion inhibitor. Substances that can be directly adsorbed or attached to the metal surface, or form an insoluble protective film due to a secondary reaction to isolate the metal from the medium, such as the hydrolyzate of nitrite dicyclohexylamine can be adsorbed on the metal surface; containing nitrogen, phosphorus, Organic substances with lone electron pair elements such as sulfur and oxygen can directly form a chemisorption layer on the metal surface. zinc sulfate and chlorinated creases generate hydroxides in the cathode area, and they are also masking corrosion inhibitors.
Anodic corrosion inhibitor. It has oxidizing properties and can passivate the metal surface and inhibit metal corrosion, such as chromate, nitrite, phosphates, molybdate and acetoxime. Pay special attention when using, as insufficient concentration will aggravate local corrosion. SHMP chemical is such an anode type corrosion inhibitor.
Cathodic corrosion inhibitor. A substance that can eliminate or reduce the depolarizer or increase the polarization of the cathode process (that is, it can increase the overpotential of the cathode reaction). Such as fat, hydrazine, sodium sulfite, etc. can remove dissolved oxygen; arsenic, sulphur, bismuth, mercury salts can increase hydrogen evolution overpotential.
Why SHMP Chemical Can Be Used As Corrosion Inhibitor
First of all, we need to know about the reason why objects can be corroded. Anaerobic bacteria has highly corrosive. It can live in places where oxygen is lacking. Can produce strong destructiveness: especially in places with sufficient nutrients, such as sulfur, its products are highly corrosive. Can cause local corrosion, perforation, and extremely difficult to handle. Iron bacteria widely exist in water sources and can convert Fe into FeO. Nitrifying bacteria can convert NH3 to NO3-, lower the pH value, and make water corrosive.
Therefore, to make polyphosphate chemical play a better corrosion inhibition effect, the cooling water requires a certain amount of divalent metal ions, such as calcium, iron or zinc ions. Sodium hexametaphosphate can form complex ions in a peptized state with divalent metal ions such as Ca2+, Mg2+, Zn2+, Fe2+, etc., and rely on corrosion current to deposit on the surface of the metal cathode to form an electrodeposition layer protective film, inhibiting the cathodic reaction to reduce the corrosion rate And play a role in corrosion inhibition.