Brief Introduction and Applications of Aluminum

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Aluminum, a kind of light metal, its compounds are widely distributed in nature and its content in Earth’s crust is only second to oxygen and silicon. In the metal species, aluminum only ranks after steel and becomes the second largest categories of metals. It is one of the most commonly used industrial metals that has special chemical and physical specialty. Besides, it not only has light weight and solid quality, but also has good ductility, electrical conductivity, thermal conductivity, heat resistance and nuclear radiation resistance and has become the important basic raw materials in the national economic development.

The density of aluminum is 2.7 which is about 1/3 of common metals. The electrical conductivity of commonly used aluminum conductor is about 61 percents of copper and its hest conductivity is half of silver. Although pure aluminum is extremely soft and has rich ductility, it can still be hardened by cold working and being made into alloys. Bauxite is an important source of aluminum. In the production process, two pounds of bauxite are needed for producing one pound of aluminum oxide and two pounds of aluminum oxide are needed for producing one pound of metal aluminum.

Aluminum is mostly existed in the form of oxide, hydroxide and oxygen-bearing aluminosilicate, while its native metals are rarely seen by us. Currently there are more than 258 kinds of known aluminum-bearing ores, among which the common ores are about 43 kinds. In fact, the aluminum deposits composed with pure ore are not existed, which are generally distributed in symbiosis and mixed with impurities. From the economic and technical point of view, not all aluminum-bearing ores can be used as industrial raw materials. Among them, bauxite composed with diaspore, boehmite or gibbsite are mainly used in abstracting metal aluminum.

Aluminum production mainly includes two parts: producing aluminum oxide from ore and using aluminum oxide to manufacture metal aluminum. The main production methods of aluminum oxide include Bayer process, soda-lime sintering process and Bayer-sinter combination method, etc, while the main production method of metal aluminum is Cryolite-alumina melting salt electrolysis.

The main application form of aluminum is aluminum alloy rather than pure metal aluminum. This is because after being mixtured into aluminum alloy, the performance of aluminum will obviously be improved, for example, its strength and corrosion resistance are improved. Based on different forming methods, aluminum alloys can be divided into cast aluminum alloy and wrought aluminum alloy. Cast aluminum alloy can be made into casting which is produced by casting method and wrought aluminum alloy can be used as plates, strips, foils, tubes, sticks, models and wire rods which are produced by pressure processing method.

As aluminum has excellent performance, it is widely used in national economic sectors and national defense industry. Aluminum, served as the lightweight construction materials, has light weight and high strength. Therefore, a large number of aluminum are used in various land, sea, and air vehicles, especially used in aircraft, missile, rocket, man-made earth satellites and so on. For example, the aluminum dosage of one supersonic aircraft occupies 70 percents of its weight and the aluminum dosage of one missile occupies more than 10 percents of its total weight; the vehicles made by aluminum and its alloys can help to reduce the energy consumption and the saving energy will far surpass its energy consumption in aluminum metallurgy; in the construction industry, aluminum alloys can be used in making windows and structural materials; in the electric power transmission fields, the dosage of aluminum occupies the biggest proportion and 90 percents of high voltage wire are produced by it; in the food industry, aluminum can be mostly made into storage tank , tin can and even the beverage container; besides, aluminum powder can be used as reducing agent of refractory metals (such as molybdenum and so on) and the desoxidant in steelmaking. Pots, basins and other products used in everyday life are mostly made from aluminum.

Aluminum compounds such as aluminum hydroxide cannot only be used in the preparation of aluminum salt, adsorbent, mordant and ion-exchange material, but also can be used as raw materials of porcelain glaze and refractories. In the medicine industry, it also has the effect of neutralizing stomach acid and curing ulcers; aluminum chloride anhydrous is the commonly used catalysts in oil industry and organic synthesis; aluminum chloride hexahydrate can be used in the preparation of deodorant and security disinfectant; Na3AlF6 (same with cryolite) is generally used as insecticide in the agricultural insudtry; when encountered with dampness or acid ,aluminum phosphide can release toxic phosphine gas which can kill the pests, so it can be used as the fumigant for killing the granary pests in agricultural industry; aluminum silicate are often used in producing glass, ceramics, the pigment of oil paint and the padding of oil paint, rubber and plastic. In recent years, people have developed some of new aluminum-bearing compounds, such as the aluminum oxide used as the wearing layer of composite floor, also aluminum alkyl, nanometer aluminum oxide and so on. With the development of science, people will make full use of aluminum and its compounds to benefit mankind.