1. Atmospheric corrosion: atmospheric corrosion of metal materials mainly depends on the water vapor in the atmosphere and the water film on the surface of the material. The atmospheric relative humidity is called the critical humidity when the corrosion rate of metal atmosphere begins to increase sharply. The critical humidity of copper alloy and many other metals is between 50% and 70%. The atmospheric pollution has a significant enhancement effect on the corrosion of copper alloy. Plant decay and factory exhaust gas, ammonia and hydrogen sulfide gas in the atmosphere, ammonia significantly accelerate the corrosion of copper and copper alloy, especially stress corrosion. C02, SO2, NO2 and other acidic pollutants in the urban industrial atmosphere dissolve in the water film and hydrolyze, making the water film acidified and the protective film unstable.
2. Splash zone corrosion: the corrosion behavior of copper alloy in the splash zone of sea water is very close to that in the ocean atmosphere. Any copper alloy with good corrosion resistance to harsh Marine atmospheres will also have good corrosion resistance in the splash zone. The spatter zone provides sufficient oxygen to accelerate the corrosion of steel, but makes the copper and copper alloy more easily remain blunt. The corrosion rate of copper alloys exposed to the splash zone usually does not exceed 5μm/a.
3. Stress corrosion: the season crack of brass is a typical representative of stress corrosion of copper alloy. Seasonal cracks, discovered in the early 20th century, are cracks in the upper part of a shell casing that crumple toward the warhead. This phenomenon often occurs in the tropics, especially during rainy seasons, hence the name seasonal cleft. Because it is related to ammonia or ammonia derivatives, it is also called ammonia crack. In fact, the presence of oxygen and other oxidants, and the presence of water are also important conditions for stress corrosion of brass.
4. Decomposition corrosion: brass dezinc is one of the most typical copper alloy decomposition corrosion, can be accompanied by stress corrosion process at the same time, can also occur alone. There are two forms of dezincification: one is lamellar shedding type dezincification, showing uniform corrosion form, relatively small harm to the use of materials. The other is the deep bolt-like development type of dezincization, in the form of pit corrosion, so that the material strength decreased significantly, great harm.
5. Marine environment corrosion: copper alloy corrosion in the Marine environment in addition to the Marine atmosphere, there are sea water splashing area, tidal range and full immersion area.
Post time: Jun-27-2022