*2.2.1.9 Corrosion and rust inhibitor*

Corrosion and rust inhibitors are additives that reduce or eliminate rust (corrosion of iron and steel) and corrosion by neutralizing acids and forming a protective film, either adsorbed or chemically bonded on the metal surfaces. Preferential adsorption of polar constituent on metal surface forms the protective film that prevents corrosive materials such as organic acids from reaching and attacking the metal. These are usually compounds having a high polar attraction towards metal surfaces such as succinates, alkyl earth sulfonates, metal phenolates, fatty acids, amines as well as zincdithiophosphates. Some of these inhibitors are specific to protecting certain metals. Hence, an oil may contain several types of corrosion inhibitors.
