The anti-rust principle of sodium nitrite is that the passivation effect plays a surface protective layer, and the air is isolated to prevent oxidation.
Sodium nitrite aqueous solution is alkaline, is a strong oxidant and reductive, will gradually oxidize in the air, the surface will become sodium nitrate, heated to 320℃ above decomposition, can also be oxidized by oxidants; In case of weak acid decomposition, brown nitrogen dioxide gas is released.
Sodium nitrite is an anodic corrosion inhibitor and an oxide film inhibitor, which forms an extremely thin and dense oxide film in a blunt state on the metal surface, causing metal ionization to be blocked, inhibiting the corrosion electrochemical anode reaction, and slowing down metal rust.
Sodium nitrite is used in anti-rust water, which needs to reach a certain concentration and a certain PH value. The concentration is about 5%, the PH value is 8-10.
Sodium nitrite is an anodic corrosion inhibitor, also known as oxidative corrosion inhibitor.
Sodium nitrite and metal to form a protective film (oxide film), the formation of insoluble oxides covering the metal surface to protect the anode region, resulting in an increase in anode polarization, thereby inhibiting the anode process of the metal.