Aluminium
Aluminium or aluminum (in North American English) is a chemical element in the periodic table with the symbol Al and atomic number 13. A silvery and ductile member of the poor metal group of elements, aluminium is found primarily as the ore bauxite and is remarkable for its resistance to oxidation (aluminium is actually almost always already oxidized, but is usable in this form unlike most metals), its strength, and its light weight. Aluminium is used in many industries to make millions of different products and is very important to the world economy. Structural components made from aluminium are vital to the aerospace industry and very important in other areas of transportation and building in which light weight, durability, and strength are needed.
Notable characteristics
Aluminium is a soft, lightweight and but strong metal with a dull silver-gray appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air and which prevents further corrosion. Aluminium weighs about one-third as much as steel or copper; is malleable, ductile, and easily machined and cast; and has excellent corrosion resistance and durability. It is also nonmagnetic and nonsparking and is the second most malleable metal and the sixth most ductile.
Applications
Whether measured in terms of quantity or value, aluminium's use exceeds that of any other metal except iron, and it is important in virtually all segments of the world economy. Pure aluminium is soft and weak, but it can form alloys with small amounts of copper, magnesium, manganese, silicon, and other elements to make alloys having a variety of useful properties.These alloys form vital components of aircraft and rockets. When aluminium is evaporated in a vacuum it forms a coating that reflects both visible light and radiant heat. These coatings form a thin layer of protective aluminium oxide that does not deteriorate as silver coatings do. Coating telescope mirrors is another use of this metal.
Some of the many uses for aluminium are in
- Transportation (automobiles, airplanes, trucks, railcars, marine vessels, etc.)
- Packaging (cans, =]
- , etc.)
- Construction (windows, doors, siding, etc.)
- Consumer durable goods (appliances, cooking utensils, etc.)
- Electrical transmission lines (because of its light weight, even though its electrical conductivity is only 60% of copper's)
- Machinery.
Its oxide, alumina, is found naturally as corundum, emery, ruby, and sapphire and is used in glass making. Synthetic ruby and sapphire are used in lasers for the production of coherent light.
Aluminium oxidizes very energetically and as a result has found use in solid rocket fuels and thermite.