A chemical element. Chemical symbol Al, atomic number 13, atomic weight 26.981539, belongs to the periodic ⅲa family. 1825 Danish h.c. The use of anhydrous aluminum chloride and potassium amalgam, aluminum amalgam, evaporation of mercury for the first time made of metal aluminum; 1827 Germany F. The metal is recovered from anhydrous aluminum chloride by using metal potassium as a reducing agent. Since then, because of the high cost of production, metal aluminum prices have been very expensive. In the 1886, C.m Hall of the United States and the French p.l.t Eroux independently invented the method of molten salt for electrolytic alumina and cryolite, which greatly reduced the price of aluminum and became a useful metal.
The aluminum content in the Earth's crust is 8%, second only to oxygen and silicon. Because the chemical nature of aluminum is lively, not in the natural state of metal, and aluminum silicate in the form of widely distributed in rock, soil and moving, plant body, minerals have bauxite, corundum, alum, ice spar. Modern metal aluminum is made by electrolysis, the purified alumina dissolved in ice crystals, with steel electrolytic groove graphite lining as cathode, graphite rod as anode, in 1000 ℃ electrolytic, Yu Yang extremely liquid metal aluminum, the purity can reach 99.8%.
Aluminum is silver-white light metal, melting point 660.37 ℃, boiling point 2,467 ℃, relative density 2.702. Pure aluminum is softer and has good ductility, conductivity and thermal conductivity. Aluminum is a lively metal, at room temperature and dry air, aluminum surface formation thickness of about 50 of the dense oxide film, so that aluminum will not be further oxidized, and the ability to water corrosion. In cold concentrated sulfuric acid or concentrated nitric acid, the surface of aluminum is oxidized to form a passivation oxide film. Aluminum can and halogen, sulfur, nitrogen, phosphorus, carbon, and silicon, copper, iron, zinc, tin, magnesium, manganese forming alloy. Aluminum is bisexual, can dissolve in acid, form aluminum salt, also can dissolve in alkali, produce aluminate.
The electron configuration of aluminum is (Ne) 3s23p1, which usually behaves as +3 valence in compounds, such as Al2O3, AlCl3, Al2 (SO4) 3; only at elevated temperatures can a valence compound, such as ALCL, be formed. Aluminum is easy to form alum, known as aluminum alum, such as Kal (SO4) 2 12h2o.
Although the conductivity of aluminum is only 2/3 of copper, but the proportion of aluminum is less than 1/3 of copper, the same weight of aluminum is more conductive than copper, so the aluminum is used to make a large number of wire, cable, electrical equipment and telecommunications equipment. The proportion of aluminum alloy is much smaller than steel, and is widely used in the manufacture of aircraft, automobiles, rockets, aerospace vehicles, and also used for making doors and windows, eaves, shutters and decorative materials. Aluminum or reductant in metallurgical industry, the aluminum powder and Fe2O3 (or Fe3O4) powder according to a certain proportion of mixing, ignited by ignition, the reaction produces high temperature, up to 3,000 ℃, so that the reduction of iron melting to weld the rail, etc., this method is also used to smelting nickel, chromium, manganese, vanadium refractory metal. Aluminium is also used to make mirrors for precision instruments such as reflective telescopes, producing paints and fireworks. The manufacture of cookware and cutlery in the commodity industry.
Aluminum is an element whose chemical symbol is AL and its atomic number is 13.
Aluminum has special chemical and physical properties, is one of the most commonly used industrial metals, not only light weight, strong texture, but also has a good ductility, conductivity, thermal conductivity, heat resistance and radiation resistance, is an important basis for the development of the national economy of raw materials.
The content of aluminum in the Earth's crust is second only to oxygen and silicon, which is the third most abundant metal element in the Earth's crust. Among the metal varieties, the second largest type is the steel.
Physical and chemical properties
Aluminum is a light metal. Pure aluminum is silvery-white, because it is easy to combine with oxygen in the air, producing a dense oxide film (alumina Al2O3) on the surface, so it is usually slightly silvery gray.
Aluminum can react with dilute strong acids (such as acid, dilute sulfuric acid, etc.) to generate hydrogen and corresponding aluminum salts. Unlike ordinary metals, it can also react with strong bases to form sodium aluminate and hydrogen. It is therefore considered that aluminum is a amphoteric metal.
At room temperature, aluminum is deactivated in concentrated nitric acid and concentrated sulfuric acid, and does not react with them, so concentrated nitric acid is transported in aluminum cans (which can last for about 180 hours).
Pure aluminum is more soft, loss of tension at around 300 ℃. The aluminum alloys that are handled are light and resilient.
Aluminum recovery is not high.
According to the main component content of aluminum ingots can be divided into three categories: high-grade pure aluminum (aluminum content 99.93%-99.999%), Industrial high-purity aluminum (aluminum content 99.85%-99.9%), Industrial pure aluminum (the content of aluminum 98%-99.7%).
Aluminium alloys are widely used in the manufacture of airplanes, automobiles and rockets because of their lighter quality and higher strength.
Because aluminum has a good conductivity and thermal conductivity, can be used as ultra-high voltage cable material. High purity aluminum has better performance.
Aluminum is very reductive at high temperature and can be used for smelting high melting point metals. (This method of smelting metal is called "aluminum Thermal Method")
Aluminum rich malleable, can be made into aluminum foil, used for packaging.
Over the past 50 years, aluminum has become one of the most widely used metals in the world. In addition to the above, in the construction industry, due to the stability of aluminum in the air and anode treatment after the excellent appearance of the great application; aluminum alloy materials are also used extensively in the aviation and defense military sectors, and in electric power transmission, high strength steel wires are commonly used to repair aluminum cables; container transportation, daily necessities, household appliances, machinery and equipment require a large amount of aluminum.