Aluminum resistance

U. Basu, A. Basu, and G. J. Taylor, Differential exudation of polypeptides by roots of aluminum-resistant and aluminum-sensitive cultivars of Triticum aestivum L. in re.spon.se to aluminum stress. Plant Physiol. 706 151 (1994). 

S. J. Zheng, j. F. Ma, and H. Matsumoto, Continuous secretion of organic acid is related to aluminum resistance in relatively long-term exposure to aluminum stress. Phy.siol. Plant 703 209 (1998). 

Aluminum is a soft, ductile, and relatively inexpensive metal. The surface of aluminum readily oxidizes in the air and water to form a highly resistant oxide film. This oxide film serves to make aluminum resistant to attack when used in environments containing sulfides, sulfur dioxide, carbon dioxide, and other corrosive gases. It is highly resistant to water-initiated corrosion, but is susceptible to galvanic corrosion by trace amounts of copper, tin, lead, nickel, or carbon steel. The reaction of aluminum in water to form Bayerite is shown in FIGURE 9-2. 

The toxicity of aluminum has been recognized most clearly by the development of bone disease caused by deposition of A1 in bones of patients on hemodialysis and in infants on intravenous therapy/ 6 Excessive A1 in the water used for dialysis may also cause brain damage. Dietary aluminum may be one cause of Alzheimer s disease/ h but this is controversial as is a possible role of aluminum in vaccines in causing inflammation in muscle.1) Solubilization of soil aluminum by acid rain has been blamed for the decline of forests in Europe and North America,) for the death of fish in acid waters,k and for very large reductions in yield for many crops/ An aluminum-resistant strain of buckwheat makes and secretes from its roots large amounts of oxalate which binds and detoxifies the Al3+ ions. ... 

The lightness and relative ease of fabrication of aluminum and its alloys are factors favoring the use of these materials. Aluminum resists attack by acids because a surface film of inert hydrated aluminum oxide is formed. This film adheres to the surface and offers good protection unless materials which can remove the oxide, such as halogen acids or alkalies, are present. 

Gaume, A., Machler, F., and Frossard, E., Aluminum resistance in two cultivars of Zea mays L. root exudation of organic acids and influence of phosphorus nutrition. Plant Soil, 234, 73-81, 2001. 

CHEMICAL PROPERTIES similar chemical properties to aluminum resistant to attack by acid due to the formation of a thin oxide film finely divided or amalgamated metal reacts with HCl, dil H2SO4, and dil HNO3 attacked by strong bases with evolution of H2 resistant to oxidation at ordinary temperatures high thermal conductivity HC (0.437 cal/g°C 30°C) latent heat of fusion (3.5 kcal/mol)... 

Stainless steels and aluminum resist tarnish in industrial, urban, and rural atmospheres, as is apparent from their satisfactory use over many years as... 

Two foam insulation systems prepared by the A. D. Little Company of Cambridge, Massachusetts were also tested. These systems had two vapor barriers, one on the outer surface (Z/Z x and one at Z/Zj j x 0.62 (where Z is the distance into the insulation from the outer surface and Z the insulation thickness). Each vapor barrier was a laminate composed of one layer of mylar [0.013 mm (0.0005 in) thick], two layers of aluminum [0.025 mm and 0.013 mm (0.001 in and 0.0005 in) thick], another layer of mylar [0.013 mm (0.0005 in)], and a layer of dacron woven fabric [33.9 g/m (1.0 oz/yd )]. The two layers of mylar offer tensile strength, the two layers of aluminum resist gas diffusion, and the dacron cloth resists tearing. Both systems used foams which had chopped fiberglass added for reinforcement. One system used Sta-foam AA1602 (a toluenedi isocyanate), whereas the other used Upjohn 452 (a pol3nnetric isocyanate). As can be seen from Fig. 13b, both systems had fair thermal performance Initially, but the performance deteriorated rapidly with thermal cycles. 

Why is aluminum resistant to oxidation by air or water even though the standard reduction potential for the metal indicates that it should be rather easily oxidized ... 

In addition to uses in electronic packaging, aluminum nitride is valuable wherever high strength and high thermal conductivity are needed. Examples are as crncibles for aluminum melting, for baUistic armor, and for aluminum resistant refractory ware. 

Aluminum and its alloys have been extensively used for structural applications with success. Aluminum resists corrosion from the atmosphere if there is an absence of narrow crevices. Many statues erected, over a hundreds of years ago, have not deteriorated badly which is in contrast with aluminum cables used in seawater. The corrosion resistance of aluminum is due to its tendency to form a compact oxide layer over the surface. The oxide formed offers a high resistance to corrosion. The normal surface film present in air is about 1 nm thick. The film thickness increases at the elevated temperature. The film growth is more rapid in water than in oxygen. 

Aluminum resists steam condensate. Steam condensate is relatively pure water that is usually saturated with oxygen and carbon dioxide, making it corrosive to steel. The corrosion resistance of aluminum alloys is not decreased significandy by these dissolved gases or by the additives used to provide the required compatibility with steel. 

With aluminum, resistance to corrosion depends much more on solder composition than it does with copper, brass, or ferrous metals. All soldered alumi-... 

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