Often the first names of something - a device, material or product - most accurately and clearly reflect their essence. And then comes the period of reflection and comes a new name, scientific, in which the understandable “worldly” meaning goes into oblivion. Once aluminum was called alumina, i.e. “Clay of the earth”, and clay, as you know, the primary essence of the earth. Now so called alumina. And the former name “alumina” was replaced by a new name - “aluminum” - beautifully, mysteriously and scientifically. The legend of the first advent of aluminum has a sad end: to the master, who gave the emperor Tiberius an amazing bowl of hitherto unknown metal, to save a single copy, just in case, they chopped off his head - he found someone to give. In those days, at the beginning of our era, secrecy issues were resolved cardinally, and gratitude for mastery was also peculiar. Be that as it may, but only after fifteen centuries, Paracelsus found that alumina (alum), used to fix paints in fabrics and leathers, contains oxide of an unknown metal.
Pure metal was obtained only in 1825. Danish scientist Oersted received a “piece of metal similar to tin” as a side effect of his research, but did not continue to work. However, by the middle of the 19th century, aluminum - silver, lightweight, easy to process metal - was valued more than gold. The properties of aluminum were primarily appreciated by jewelers. He was in fashion, and at an exhibition in Paris in 1855, aluminum products were on display next to the diamonds of the French crown. As you know, demand leads to an increase in supply, so production technologies have received an impetus for development. And by the middle of the twentieth century, aluminum had become a common material widely used in technology, and the physical properties of aluminum were already well studied.
Technologies for industrial production of aluminum
The basis of aluminum production is electrolysis, and the raw material is aluminum oxide Al2O3 dissolved in the cryolite melt. For electrolysis, baths are used, the working temperature of which is slightly less than 1000 ° C. Liquid aluminum is collected at the bottom of the bath - this is the cathode of the installation. Pour it into molds and get ingots or ingots - raw materials for further processing.
The properties of aluminum are changed in the right way with the help of alloying additives. At the same time, they increase the strength, hardness, heat resistance, etc. specific to the application. Alloying materials for various alloys - copper, manganese, zinc, magnesium, as well as (in small quantities) silicon, iron, nickel, etc. are added to the melt during the final manufacture of the desired type of finished product.
Basic physical properties of aluminum
Any material is characterized by a set of physico-chemical properties, which determines its subsequent use. The properties of aluminum - ductility, low specific gravity, good heat and electrical conductivity - are known to all.
- Density of aluminum - 2.710 kg / m3
- Melting point - 660 ° C
- Boiling Point - 2519 ° C
- The electrical resistivity is 2.7 * 10−8 Ohm m / mm sq.
From the point of view of application in electrical engineering, the magnetic properties of aluminum, according to which it belongs to low-magnetic substances of the paramagnet group, are of undoubted interest. This class of materials is characterized by the fact that its magnetic field under the action of an external field coincides with it in direction, and, although very slightly, it is amplified.
Aluminum application
The value of the material determines the demand for products from it. Aluminum is in demand primarily as a structural material. Ease of processing and corrosion resistance allow the use of aluminum products in construction, engineering, for the manufacture of thermal, food and other types of equipment. Aluminum is the main structural material of aviation. Aluminum alloys are increasingly used in shipbuilding - ship hulls, communications, deck superstructures, and various marine equipment. Duralumin and silumin are widely used in industry and in everyday life - non-corrosive alloys of aluminum with copper - up to 7% or silicon - up to 14%.
The electrical conductivity of aluminum is slightly inferior to copper, but aluminum is much lighter and cheaper than its widespread use in electrical engineering. At the same time, the main properties of aluminum for such an application are low electrical resistance, weight and low cost. Increasingly, in electrical equipment, where recently only copper conductors reigned supreme, aluminum windings of transformers, inductors, reactors, cable conductors, etc. are used. The main transmission lines are also largely indebted to aluminum.
There is no doubt that this amazing metal has not yet revealed its full potential - this remains to be done in the future.