What are the properties of zinc salts as corrosion inhibitors?

Zinc salts form a film relatively quickly, but this film is not durable; therefore, zinc salts are safe yet inefficient corrosion inhibitors, and thus cannot be used alone. It works well when used in combination with other polyphosphates, low concentrations of chromates, and organic phosphates. Because zinc salts can accelerate the film-forming process of these corrosion inhibitors, while also maintaining the durability of these films. Zinc is toxic to aquatic organisms, so its use is restricted; another drawback is that it tends to form precipitates at pH > 8.3. In the low-zinc salt compound, the zinc ion concentration is <1.5 MG/L, ensuring that the concentration of all zinc ions remains below the emission standards set by environmental regulations

In cooling water systems, zinc salts are the most commonly used cathodic corrosion inhibitors, with zinc ions being the active component. Zinc salts form a film relatively quickly, but this film is not durable; therefore, zinc salts are safe yet inefficient corrosion inhibitors, and thus cannot be used alone. It works well when used in combination with other polyphosphates, low concentrations of chromates, and organic phosphates. Because zinc salts can accelerate the film-forming process of these corrosion inhibitors, while also maintaining the durability of these films. Zinc is toxic to aquatic organisms, so its use is restricted; another drawback is that it tends to form precipitates at pH > 8.3. Therefore, the low-zinc composite formulations are commonly used in China at present, with Zn2+ levels below 1.5 MG/L, ensuring that the concentration of all zinc ions is below the emission standards set by environmental regulations.