Do you know anything about automobile antifreeze? "Antifreeze", namely engine coolant, is an indispensable cooling medium for the normal operation of automobile engines, which is also the cooling medium circulating in the engine cooling system. As we all know, the working state of the cooling system is closely related to the working condition of the car. Once the cooling system has problems, it may even damage the engine, causing cylinder pulling and other consequences. It can be seen that antifreeze is not optional, but very important.
Antifreeze has two obvious physical characteristics: low freezing point and high boiling point. Therefore, it can not only ensure the normal operation of the car cooling system in winter, but also prevent the boiling of cooling water in summer to avoid "boiling". Antifreeze is a substitute for water. Because it is cold in winter, zero temperature water will freeze, and the freezing point of antifreeze is very low, so it will not freeze. Because the antifreeze does not contain water and alkali, long-term use will not cause water channel blockage. In addition, the antifreeze contains special additives, which can prevent rust and corrosion and protect the cooling system. The function of antifreeze directly affects the performance and service life of automobiles. The anti-corrosion function plays an important role in the life of the engine cooling system. Because the engine and its cooling system are made of metal, including copper, brass, cast iron, cast aluminum, steel, and soldering tin, these metals will be corroded and rusted after contacting with the cooling water under high temperature. The high-quality antifreeze will not cause corrosion to the engine cooling system, but also has anti-corrosion and rust removal functions, which can better protect the water tank and prolong the service life of the water tank and the engine.
Anticorrosion Mechanism of Benzotriazole Benzotriazole is a kind of precipitation film Corrosion Inhibitor, which is a good rust and corrosion inhibitor for many metals, especially for copper and copper alloys. It has a unique and excellent corrosion inhibition and protection effect, and is most effective in inhibiting discoloration corrosion of copper or copper alloys. Therefore, it is widely used in the surface anti-corrosion treatment of copper or copper alloy parts, the passivation and protection treatment of brass imitation gold coating, the coating protection and vapor phase sealing of copper and copper alloy parts. Benzotriazole is an organic heterocyclic compound, and its pure appearance is white needle crystal, while commercial benzotriazole is mostly white or light yellow, and the purity is generally 95%~98%. Benzotriazole can be dissolved in water, and its solubility increases with the increase of temperature. At room temperature, i.e. 20~30 ℃, its solubility is about 1.5%~2.3%. The 0.1% aqueous solution of benzotriazole is slightly acidic, and the pH value is between 5.5 and 6.5. The solubility of benzotriazole in polar solvent is large, while that in non-polar solvent is small. Its vapor pressure is relatively high. Benzotriazole is less toxic. Generally, compared with sodium nitrite, a common inorganic corrosion inhibitor, its toxicity is only 20% of that of sodium nitrite, and less toxic than that of chromic anhydride or chromate used for copper and copper alloy passivation. Benzotriazole has high solubility in acid and alkali solutions. Domestic benzotriazole derivatives, including octaalkyl and dodecyl benzotriazole, have good corrosion inhibition and protection effects.
(BTA for short), its corrosion inhibition mechanism is that the reaction group on the benzotriazole molecule interacts with the metal ions generated in the corrosion process to form a precipitation film or insoluble coordination film, further polymerizes on the metal surface to form a precipitation protective film, thus preventing the corrosion process. Benzotriazole and its derivatives have unique and excellent corrosion inhibition performance for copper or copper alloys. The corrosion protection mechanism is: in the solution of benzotriazole, copper replaces the hydrogen atom in the NH functional group of one benzotriazole molecule at the solid-liquid interface, connects with covalent bond, and connects with the free electron of the nitrogen atom of another benzotriazole molecule with a coordination bond to form a semi permeable polymer complex.
