Aluminium applications

The good resistance of aluminium to nitrate and ammonia environments makes it useful in production plants, namely for buildings, as internal cladding of granulation towers, etc. [2]. 

Granulated fertilisers are transported in bulk in aluminium tippers. Solutions of nitrate fertilisers can be transported and stored in aluminium tanks. 

When the contact is intermittent, as in irrigation equipment made of aluminium, the shorter the contact time of the fertiliser solution, the lesser is the risk of pitting corrosion. Nevertheless, these installations should be rinsed carefully after being used with fertiliser solutions. 

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Pores in the inside lacquer of aluminium tubes allow the preparation to react with the aluminium. The inside lacquer therefore has to be tested for the presence of pores and adherence onto the aluminium. Application of a copper sulfate solution demonstrates the presence of pores in the inside lacquer. The pores become visible due to a rust-coloured discoloration of the aluminium. 

This very good resistance to corrosion, as much as lightness, explains the development of numerous aluminium applications and offers users a number of major advantages ... 

Whenever possible, the choice of an alloy should be based on the experience that has been gained, often over decades, with aluminium applications. First, this experience provides a valuable guidance for selection, once the decision to use aluminium has been taken. Second, experience forms the basis for the development of new applications, by comparison with what is being done, or what has been done. 

Besides stmctural variety, chemical diversity has also increased. Pure silicon fonns of zeolite ZSM-5 and ZSM-11, designated silicalite-l [19] and silicahte-2 [20], have been synthesised. A number of other pure silicon analogues of zeolites, called porosils, are known [21]. Various chemical elements other than silicon or aluminium have been incoriDorated into zeolite lattice stmctures [22, 23]. Most important among those from an applications point of view are the incoriDoration of titanium, cobalt, and iron for oxidation catalysts, boron for acid strength variation, and gallium for dehydrogenation/aromatization reactions. In some cases it remains questionable, however, whether incoriDoration into the zeolite lattice stmcture has really occurred. 

Many of the uses of boron and aluminium compounds have already been discussed. The elements and a number of other compounds also have important applications. 

Aluminium oxide. The commercial material, activated alumina, is made from aluminium hydroxide it will absorb 15-20 per cent, of its weight of water, can be re-activated by heating at 175° for about seven hours, and does not appreciably deteriorate with repeated use. Its main application is as a drying agent for desiccators. 

Potassium and sodium borohydride show greater selectivity in action than lithium aluminium hydride thus ketones or aldehydes may be reduced to alcohols whilst the cyano, nitro, amido and carbalkoxy groups remain unaffected. Furthermore, the reagent may be used in aqueous or aqueous-alcoholic solution. One simple application of its use will be described, viz., the reduction of m-nitrobenzaldehyde to m-nitrobenzyl alcohol ... 

Copper, aluminium, steel and galvanized iron are the most widely used metals for the purpose of grounding. Choice of any of them will depend upon availability and economics in addition to the climatic conditions (corrosion effect) at the site of installation. In Table 22.3 we provide a brief comparison of these metals for the most appropriate choice of the metal for the required application. 

In humid and corrosive conditions, aluminium erodes faster than copper. These solid or hollow conductors connect the stipply side to the receiving end and are called bus ducts. They may be of the open type, stich as are used to feed a very high current tit very low voltage. A smelter unit is one such application. Btit nonnally they are housed in a sheet mettil enclostiie.. See Figtires 28.2(a) and 28.33(b). 

The resistivity and conductivity of standard annealed copper and a few recommended aluminium grades being used widely for electrical applications are given in Table 30.1. Their corresponding current-carrying capacities in percent, with respect to a standard reference (say, 100% lACS) are also provided in the table. 

Aluminium alloy is much less good (Fig. 11.8) - it can only be drawn a little before instabilities form. Pure aluminium is not nearly as bad, but is much too soft to use for most applications. 

No fewer than 14 pure metals have densities se4.5 Mg (see Table 10.1). Of these, titanium, aluminium and magnesium are in common use as structural materials. Beryllium is difficult to work and is toxic, but it is used in moderate quantities for heat shields and structural members in rockets. Lithium is used as an alloying element in aluminium to lower its density and save weight on airframes. Yttrium has an excellent set of properties and, although scarce, may eventually find applications in the nuclear-powered aircraft project. But the majority are unsuitable for structural use because they are chemically reactive or have low melting points." ... 

Current usage is almost entirely associated with the good adhesion to aluminium. Specific applications include the bonding of aluminium foil to plastics films, as the adhesive layer between aluminium foil and polyethylene in multilayer extrusion-laminated non-lead toothpaste tubes and in coated aluminium foil pouches. Grades have more recently become available for manufacture by blown film processes designed for use in skin packaging applications. Such materials are said to comply with FDA regulations. 

Mix D is a typical plastigel. The incorporation of such materials as fumed silicas, certain bentonites or aluminium stearate gives a paste which shows pronounced Bingham Body behaviour (i.e. it only flows on application of a shearing stress above a certain value). Such putty-like materials, which are also... 

The acetal resins show superior creep resistance to the nylons but are inferior in this respect, to the polycarbonates. It is to be noted, however, that limitations in the load-bearing properties of the polycarbonates restrict their use in engineering applications (see Chapter 20). Another property of importance in engineering is abrasion resistance—a property that is extremely difficult to assess. Results obtained from various tests indicate that the acetal polymers are superior to most plastics and die cast aluminium, but inferior to nylon 66 (see also Section 19.3.6 and Chapter 18). 

In 1997 it was reported that carbon-fibre reinforced PEEK had replaced aluminium in the fuel pump suction manifold of the Airbus. For this application the product has to withstand pressure thrusts of up to 30 bar and resist kerosene at operating temperatures in the range 40-200°C. The ventilation wheel for cooling the electric motor in the same application has also been converted from aluminium to PEEK. 

Nitrile rubber adhesives. The main application corresponds to laminating adhesives. PVC, polyvinyl acetate and other polymeric films can be laminated to several metals, including aluminium and brass, by using NBR adhesives. NBR adhesives can also be used to join medium-to-high polarity rubbers to polyamide substrates. The adhesive properties of NBR rubbers can be further improved by chemical modification using polyisocyanate or by grafting with methyl methacrylate. 

M = Al, Ga, In, Tl). The solution chemistry of Al in particular has been extensively investigated because of its industrial importance in water treatment plants, its use in many toiletry formulations, its possible implication in both Altzheimer s disease and the deleterious effects of acid rain, and the ubiquity of Al cooking utensils.For example, hydrated aluminium sulphate (10-30 gm ) can be added to turbid water supplies at pH 6.5-7.5 to flocculate the colloids, some 3 million tonnes per annum being used worldwide for this application alone. Likewise kilotonne amounts of A1(OH)2.5C1o.5 in concentrated (6m) aqueous solution are used in the manufacture of deodorants and antiperspirants. 

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