The role of chemical corrosion inhibitors

Chemical corrosion inhibitors are mainly used to prevent or slow down the corrosion process of metals in environmental media. They achieve this goal through different mechanisms, including:
Generating oxide film: Some corrosion inhibitors such as chromates and nitrites act as oxidants, which can form a dense oxide film on the metal surface, thereby slowing down the corrosion of the metal

Precipitation film formation: Certain corrosion inhibitors such as zinc carbonate, phosphate, and hydroxide can form a precipitation film on the metal surface, which can cover the entire surface of the metal and inhibit the anodic and cathodic processes of metal electrochemical corrosion
Formation of adsorption film: The polar groups in the organic corrosion inhibitor molecules can be adsorbed on the metal surface, forming a monolayer film that can prevent or slow down electrochemical reactions, thereby playing a corrosion inhibition role

Electrochemical mechanism: Corrosion inhibitors can also suppress corrosion by affecting the electrochemical processes on the metal surface, including increasing the overpotential of cathodic reactions, or generating insoluble deposits on the metal surface by reacting with anodic reaction products
Physical and chemical mechanisms: From a physical and chemical perspective, the role of corrosion inhibitors also includes the formation of oxide films, precipitation films, and adsorption films, so they are also divided into oxide film type corrosion inhibitors, precipitation film type corrosion inhibitors, and adsorption film type corrosion inhibitors 
Synergistic effect: Sometimes different types of corrosion inhibitors can be used in combination to achieve better corrosion inhibition effects than when used alone. This phenomenon is called synergistic effect

Corrosion inhibitors are widely used in the chemical industry, including the production and processing of petroleum products, chemical cleaning, atmospheric environment, industrial water, machinery, instrument manufacturing, and petrochemical production processes. They are effective means to prevent corrosion of metals and their alloys
It should be noted that the use of corrosion inhibitors should consider their potential impact on the environment, especially phosphate corrosion inhibitors that may cause eutrophication of water bodies
. Therefore, when selecting corrosion inhibitors, their environmental friendliness and suitability for specific metals should be considered.