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Corrosion resistance of shipbuilding aluminum alloy manufac
Most aluminum alloys exhibit excellent corrosion resistance in marine environment. The corrosion resistance of aluminum alloy mainly depends on the integrity of the passive film on the surface and the self repairing ability after the rupture. The destruction of the passive film is especially strong in the seawater, which results in the instability of the aluminum alloy in seawater, the pitting corrosion and crevice corrosion. In some cases, some special corrosion morphologies, such as intergranular corrosion, stress corrosion and exfoliation corrosion, and can also be produced.
The seawater flow has a significant effect on the corrosion behavior of marine aluminum alloy in seawater. The results show that the corrosion rate of 5456-H117 aluminum alloy depends on the velocity of seawater. With the increase of flow rate increased sharply, from static to the maximum flow rate of 7.6 m/s, the corrosion rate at the level of 102mm/a, that the Aluminum Alloy corrosion rate of water flow is not very sensitive, is more resistant to seawater corrosion material flow. At the same time, the metal coupling with the natural corrosion potential can accelerate the corrosion of aluminum alloy. Galvanic corrosion of 5083 aluminum alloy and 2205 stainless steel in seawater has developed galvanic corrosion. has become the protection of the sacrificial anode material of 2205 stainless steel, continuous active anode dissolution, so in seawater environment should avoid the contact of the two materials.
In addition, crevice corrosion is a common corrosion behavior of aluminum alloy in seawater. The main corrosion area is the gap of the device or structure below the waterline. At present, the cathodic protection, corrosion resistant coating and surface treatment technology are mainly used for the corrosion protection of the marine aluminum alloy.