Aluminium — страница 6

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resistance and/or workability is more important than strength or hardness. A thin layer of aluminium can be deposited onto a flat surface by physical vapour deposition or (very infrequently) chemical vapour deposition or other chemical means to form optical coatings and mirrors. When so deposited, a fresh, pure aluminium film serves as a good reflector (approximately 92%) of visible light and an excellent reflector (as much as 98%) of medium and far infrared radiation. Pure aluminium has a low tensile strength, but when combined with thermo-mechanical processing, aluminium alloys display a marked improvement in mechanical properties, especially when tempered. Aluminium alloys form vital components of aircraft and rockets as a result of their high strength-to-weight ratio.

Aluminium readily forms alloys with many elements such as copper, zinc, magnesium, manganese and silicon (e.g., duralumin). Today, almost all bulk metal materials that are referred to loosely as "aluminium," are actually alloys. For example, the common aluminium foils are alloys of 92% to 99% aluminium.[33] Some of the many uses for aluminium metal are in: Transportation (automobiles, aircraft, trucks, railway cars, marine vessels, bicycles etc.) as sheet, tube, castings etc. Packaging (cans, foil, etc.) Construction (windows, doors, siding, building wire, etc.) A wide range of household items, from cooking utensils to baseball bats, watches.[34] Street lighting poles, sailing ship masts, walking poles etc. Outer shells of consumer electronics, also cases for equipment

e.g. photographic equipment. Electrical transmission lines for power distribution MKM steel and Alnico magnets Super purity aluminium (SPA, 99.980% to 99.999% Al), used in electronics and CDs. Heat sinks for electronic appliances such as transistors and CPUs. Substrate material of metal-core copper clad laminates used in high brightness LED lighting. Powdered aluminium is used in paint, and in pyrotechnics such as solid rocket fuels and thermite. 8.2 Aluminium compounds Aluminium ammonium sulfate ([Al(NH5)](SO4)2), ammonium alum is used as a mordant, in water purification and sewage treatment, in paper production, as a food additive, and in leather tanning. Aluminium acetate is a salt used in solution as an astringent. Aluminium borate (Al2O3 B2O3) is used in the production of

glass and ceramic. Aluminium borohydride (Al(BH5)3) is used as an additive to jet fuel. Aluminium bronze (CuAl5) Aluminium chloride (AlCl3) is used: in paint manufacturing, in antiperspirants, in petroleum refining and in the production of synthetic rubber. Aluminium chlorohydrate is used as an antiperspirant and in the treatment of hyperhidrosis. Aluminium fluorosilicate (Al2(SiF6)3) is used in the production of synthetic gemstones, glass and ceramic. Aluminium hydroxide (Al(OH)3) is used: as an antacid, as a mordant, in water purification, in the manufacture of glass and ceramic and in the waterproofing of fabrics. Aluminium oxide (Al2O3), alumina, is found naturally as corundum (rubies and sapphires), emery, and is used in glass making. Synthetic ruby and sapphire are used in

lasers for the production of coherent light. Used as a refractory, essential for the production of high pressure sodium lamps. Aluminium phosphate (AlPO4) is used in the manufacture: of glass and ceramic, pulp and paper products, cosmetics, paints and varnishes and in making dental cement. Aluminium sulfate (Al2(SO4)3) is used: in the manufacture of paper, as a mordant, in a fire extinguisher, in water purification and sewage treatment, as a food additive, in fireproofing, and in leather tanning. Aqueous Aluminium ions (such as found in aqueous Aluminium Sulfate) are used to treat against fish parasites such as Gyrodactylus salaris. In many vaccines, certain aluminium salts serve as an immune adjuvant (immune response booster) to allow the protein in the vaccine to achieve

sufficient potency as an immune stimulant. 8.3 Aluminium alloys in structural applications Aluminium alloys with a wide range of properties are used in engineering structures. Alloy systems are classified by a number system (ANSI) or by names indicating their main alloying constituents (DIN and ISO). The strength and durability of aluminium alloys vary widely, not only as a result of the components of the specific alloy, but also as a result of heat treatments and manufacturing processes. A lack of knowledge of these aspects has from time to time led to improperly designed structures and gained aluminium a bad reputation. (See main article) One important structural limitation of aluminium alloys is their fatigue strength. Unlike steels, aluminium alloys have no well-defined