Aluminum soil corrosion

The interest in the uptake of phosphate by metal oxides such as iron, alumina, and titania arises from current problems found in the study of soils, corrosion, and biomimetic materials. Phosphate reactions with iron and aluminum oxides and hydroxides have been extensively studied by soil chemists because these soil conq)onents are the most abundant of the naturally occurring metal oxides (7, 2) and are the inorganic soil constituents primarily responsible for phosphate reactions in... 

Snodgrass J.S., Soil corrosion of aluminum in underground electric plasma. Corrosion NACE 75, paper No. 130. 

Aluminum-sheathed cables should not be connected to other cables because aluminum has the most negative rest potential of all applicable cable sheathing materials. Every defect in the protective sheath is therefore anodically endangered (see Fig. 2-5). The very high surface ratio SJS leads to rapid destruction of the aluminum sheathing according to Eq. (2-44). Aluminum can also suffer cathodic corrosion (see Fig. 2-11). The cathodic protection of aluminum is therefore a problem. Care must be taken that the protection criterion of Eq. (2-48) with the data in Section 2.4 is fulfilled (see also Table 13-1). Aluminum-sheathed cables are used only in exceptional cases. They should not be laid in stray current areas or in soils with a high concentration of salt. 

Titanium has an unusually high ratio of strength to weight. It is considerably stronger than either aluminum or steel, two metals with which it competes (for special purposes). Its density (4.5 g/cm3) is intermediate between that of Al (2.7 g/cm3) and that of Fe (7.9 g/cm3). Titanium is extremely resistant to corrosion by air, soil, seawater, and even such reactive chemicals as nitric acid and chlorine gas. Like aluminum, it forms a thin, tightly adherent oxide layer that protects the metal from further attack. 

Aluminum reacts with acids and strong alkali solutions. Once aluminum is cut, the fresh surface begins to oxidize and form a thin outer coating of aluminum oxide that protects the metal from further corrosion. This is one reason aluminum cans should not be discarded in the environment. Aluminum cans last for many centuries (though not forever) because atmospheric gases and soil acids and alkalis react slowly with it. This is also the reason aluminum is not found as a metal in its natural state. 

Materials such as metals, alloys, steels and plastics form the theme of the fourth chapter. The behavior and use of cast irons, low alloy carbon steels and their application in atmospheric corrosion, fresh waters, seawater and soils are presented. This is followed by a discussion of stainless steels, martensitic steels and duplex steels and their behavior in various media. Aluminum and its alloys and their corrosion behavior in acids, fresh water, seawater, outdoor atmospheres and soils, copper and its alloys and their corrosion resistance in various media, nickel and its alloys and their corrosion behavior in various industrial environments, titanium and its alloys and their performance in various chemical environments, cobalt alloys and their applications, corrosion behavior of lead and its alloys, magnesium and its alloys together with their corrosion behavior, zinc and its alloys, along with their corrosion behavior, zirconium, its alloys and their corrosion behavior, tin and tin plate with their applications in atmospheric corrosion are discussed. The final part of the chapter concerns refractories and ceramics and polymeric materials and their application in various corrosive media. 

Corrosion plays a high risk underground, in particular to aluminum which is totally unacceptable. The electrolytic properties of some soils cause corrosion to all these metals, as do stray currents produced by DC railway lines on DC high voltage systems where the earth is used as a return path. Cathodic protection can help eliminate this type of problem. 

All of the materials contain copper and most contain iron, aluminum, and silicon. Their presence can be attributed to soil contamination or to impregnation of the fibers with products of copper corrosion. Further analyses currently are being conducted to identify the generic... 

Hydrous oxides are of major interest in many areas of technology, e.g., corrosion and passivation of metals, formation of decorative, protective, and insulating films, aqueous battery systems, catalysis and electrocatalysis, electrochromic display systems, pH monitoring devices, soil science, colloid chemistry, and various branches of material science. Detailed accounts of some of the nonnoble hydrous metal oxide systems, especially aluminum,1 have appeared recently. In the case of the noble metals such as platinum or gold most of the electrochemical work to date has been concerned with compact monolayer, and submonolayer, oxide growth. 

Dissolution of steel or zinc in sulfuric or hydrochloric acid is a typical example of uniform electrochemical attack. Uniform corrosion often results from exposure to polluted industrial environments, exposure to fresh, brackish, and salt waters, or exposure to soils and chemicals. Some examples of uniform or general corrosion are the rusting of steel, the green patina on copper, tarnishing silver, and white rust on zinc on atmospheric exposure. Tarnishing of silver in air, oxidation of aluminum in air, attack of lead in sulfate-containing environments results in the formation of thin protective films and the metal surface remains smooth. Oxidation, sulfidation. 

Aluminum. Aluminum is cleaned by solvents and chemical solutions to remove oily soils and corrosion products. Cleaned aluminum is pretreated using chromate conversion coating and anodizing. 

The National Bureau of Standards underground corrosion program (Romanoff, 1957) included tests on commercial rolled zinc and a zinc-4% aluminum-1% copper. Panels were buried in representative soils in 1937, and... 

---