Corrosion resistance of copper rod

Corrosion resistance characteristics of copper radiator tubes in corrosive environment. Pure copper has high chemical stability, and its standard electrode potential is about 0.345V(SCE), which is higher than the standard electrode potential, but lower than the standard oxygen electrode potential. Therefore, copper will not produce depolarization corrosion in general aqueous solution, but oxygen depolarization corrosion. Copper is corrosion resistant when no agent is present in the corrosive medium. If the agent is present in the corrosive medium, copper will be accelerated to corrosion.

In degassed aqueous solution, nonsexual acid (HCI, dilute H. SO-) and organic acids (acetic acid, citric acid, fatty acid, lactic acid, oxalic acid), copper has a high chemical stability, will not be corroded; In degassed sulfuric acid, nitric acid, concentrated sulfuric acid, degassed sodium and other acidic or strong alkaline solution, copper will be corroded; In neutral or weakly alkaline solutions, especially in the presence of dissolved oxygen, copper can be passivated to create a film on the surface that prevents corrosion. Pure copper has good atmospheric corrosion resistance. When pure copper is exposed to the atmosphere, the purplish red Cu: O and Iu() forms on the surface, which is further corroded in the humid industrial atmosphere to form CuSO~·3Cu(OH), and CuC03·Cu(OH).

The formation of CuCl2, 3Cu(OH)2 surface protective films in Marine atmosphere can prevent further corrosion of copper. Pure copper is also resistant to microbial corrosion because copper ions (toxic) prevent or slow the growth of Marine life. However, copper will be strongly corroded in wet and gaseous media containing SU2, H2S and C12, or in ammonia, ammonium salt, chloride and other solutions. For example, when copper is corroded in the medium containing NH, NH plant or CN -, the complexation ion [Cu(NH,)+J of copper is formed, which greatly reduces the concentration of copper ion in the solution, reduces the electrode potential of copper, and accelerates the corrosion of copper.