Corrosion is the destruction of materials due to the interaction between them and the surrounding environment.
In the definition of corrosion, three aspects are included, namely, the type of material, environment and reaction. Materials include metallic materials and non-metallic materials. Material is the internal cause of corrosion, and the corrosion behavior of different materials varies greatly. The environment is the external condition of corrosion, and the concentration and composition of the medium have a great influence on corrosion. For example, steel is severely corroded in dilute sulfuric acid with a concentration of less than 60%, but a passivation film will be formed on the surface in concentrated sulfuric acid. Therefore, this characteristic of steel can be used to store and transport sulfuric acid with a concentration of more than 90%. Others such as temperature, pressure, flow rate, etc. will play a certain role in the corrosion of materials. Metallic materials and the environment usually undergo chemical or electrochemical reactions, while non-metallic materials and the environment undergo reactions such as swelling, dissolution, aging, and weathering.
Metal materials, especially steel, and non-metallic concrete are the most widely used and most used materials in national economic construction, and are also the main protection objects of anti-corrosion coatings.
