The corrosion of metals is mainly caused by chemical corrosion and electrochemical corrosion, and the corrosion of non-metallic materials is generally caused by direct chemical and physical damage.
1. Chemical corrosion
The surrounding medium directly chemically interacts with the metal under the condition of no current, and causes it to be destroyed, such as the corrosion of the metal by the high-temperature dry gas and the non-electrolytic solution.
2. Electrochemical corrosion
The metal contacts with the electrolyte to generate electron flow, which will destroy itself in the electrochemical action, which is the main form of corrosion.
Common acid-base salt solution corrosion, atmospheric corrosion, soil corrosion, seawater corrosion, microbial corrosion, pitting corrosion and crevice corrosion of stainless steel, etc., are all electrochemical corrosion.
Electrochemical corrosion not only occurs between two substances that can play a chemical role, but also because of the difference in the concentration of the solution, the concentration of the surrounding oxygen, the slight difference in the structure of the material, etc., the difference in potential is generated, and the power of corrosion is obtained. , So that the metal with low potential and in the position of positive board suffers loss.
Post time: Apr-12-2021