Galvanic corrosion of aluminum

CLIMAT (classification of Industrial and Marine Atmospheres,21 gives data on uniform or galvanic corrosion of aluminum wire wound around threaded bolts made of steel or copper in an atmosphere of interest)... 

Figure 4. Galvanic corrosion of aluminum in contact with chromium...

Idrac, G. Mankowski, G. Thompson, P. Skeldon, C. Blanc, Y. Kihn, Galvanic corrosion of aluminum-copper model alloys, Electrochim. Acta 52 (2007) 7626—7633. 

Galvanic corrosion of aluminum shielding in buried telephone cables. 

Mansfeld E., Henkel J.V., Galvanic corrosion of aluminum alloys. El. Effect of area ratio, Corrosion Science, vol. 15, 1975, p. 239- 250. 

Some semiconduaots, such as graphite and magnetite, are cathodic to aluminum, and in contaa with them, aluminum cotiodes sacrificially. The problems associated with galvanic corrosion of aluminum-graphite composites arc described in Chapter 10. 

Accelerated corrosion of a metal because of electrical contact with a more noble metal or nonmetallic conductor such as graphite in a conductive environment is called galvanic corrosion. The most common examples of galvanic corrosion of aluminum alloys in service occur when they are joined to steel or copper and exposed to a wet saline environment CFig. 1). The... 

The galvanic corrosion of aluminum is usually mild, except in highly conductive media such as seawater, wind-blown sea spray, and salted slush from road deicing salts, when corrosion can be appreciable. In natural surface waters and nonsaline atmospheres, the galvanic corrosion of aluminum is rarely significant, although rain mnoff from copper and its alloys pit aluminum qtpreciably. 

Fig.2 Galvanic corrosion of aluminum shielding in buried telephone cable coupled to buried copper plates...

Fig. 3 Galvanic corrosion of aluminum in buried power cable splice (copper to aluminum)...

Aluminum components are sensitive to ions of heavy metals, especially copper. To avoid localized galvanic corrosion of the aluminum by metallic copper reduced from copper ions, care must be exercised to prevent heavy metal ions from entering aluminum components. Note the recommendations under Elimination. ... 

Aluminum Pipe) A Heavy Wall Alclad Aluminum "Spool Piece" Will Avoid Galvanic Corrosion of Pipe... 

Aluminum alloys of the series 7000 and 2000 and 380 die-cast alloy cause serious galvanic corrosion of magnesium in saline environments, especially when the iron content of the alloy exceeds 200 ppm of iron. Data on the galvanic corrosion of... 

This facet of industry might appear to be free from corrosion. On the contrary, there are problems such as the corrosion of aluminum used for tracks on most devices. There is the high probability of strong galvanic interaction with gold used for connectors. Many critical systems must function in severe environments such as a temperature range below zero to 40 °C, 100% humidity, airborne particulate matter and insects. This is certainly a challenging problem. 

Steel corrodes by electrochemical reactions. In the presence of oxygen, at anodic areas ferric ions and at cathodic areas hydroxyl ions are formed. Aluminum generally corrodes more slowly than steel because of a dense, coherent layer of aluminum oxide. However, aluminum corrodes more rapidly than iron under either highly acidic or basic conditions. Also, salt affects the corrosion of aluminum more than it affects the corrosion of iron. Galvanized steel is protected since zinc acts as a sacrificial anode and a barrier preventing water and oxygen from reaching the steel surface. 

SiCMp also have carbon cores and carbon-rich surfaces [49], with resistivities on the order of 10 cm [44], Consequently, in aqueous solutions, SiC can serve as an inert electrode for proton and oxygen reduction. Depending on the type of SiC, galvanic corrosion with aluminum is possible. 

GRAPHITE Alloys 3003, 5154 and 6061 were resistant to solid graphite in laboratory tests under conditions of 100% relative humidity at ambient temperature and 54 C (130 F). Other laboratory tests have shown that graphite smears on aluminum are corrosive because of galvanic corrosion of the aluminum. See also Ref (3) p. 50, (5) p. 13. 

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