Aluminium is a lightweight metal silver-white color with a face-centered cubic lattice, in a free form, it does not occur.Its most important mineral bauxite is a mixture of aluminum hydroxides: boehmite, gibbsite and the diaspora.We found hundreds of minerals, aluminum, most of them related to aminosilikatam.
Aluminum has a valuable combination of properties: a low density, high electrical and thermal conductivity.This is easily the metal stamping and forging, welded good contact, gas and other types of welding.Its reflectivity close to silver (about 90% of the incident light energy), the aluminum is well polished and anodized.
Unlike most other metals, the strength properties of aluminum increases when cooled below 120 K, and plastic do not change.
In air, it is covered by a thin solid non-porous film which protects the metal from further oxidation.This film causes its high corrosion resistance.
aluminum does not react with concentrated or highly dilute nitric acid does not react with fresh water and sea water as well as food.However, technical aluminum exposed to dilute hydrochloric acid and alkali.By reaction with alkali aluminates it forms.
The aluminum industry is obtained by the electrolysis of alumina in molten cryolite, which is carried out at a temperature of 950 ° C.It uses an electrolyte bath, made in the form of the iron casing with electrical and heat-insulating material inside.Cathode serves hearth bath and anode - carbon blocks or printed Söderberg electrodes immersed in an electrolyte.On hearth accumulated aluminum, and the anode - oxygen and carbon dioxide.
Aluminum is widely used in almost all fields of technology.In most cases, it is used in alloys with other metals.It successfully replaces copper in electrical engineering in the production of massive conductors.The electrolytic conductivity of aluminum is 65.5% of the conductivity of copper.However, it is three times lighter than copper, so the weight of aluminum wire is half the mass of copper.
for power rectifiers and capacitors used ultra-pure aluminum, their action is based on the ability of the metal oxide film to pass an electric current in only one direction.
- HiMiK.ru, Aluminium