Aluminum - general characteristics of the element, chemical properties
Aluminum is an element of the main subgroup of group III, third period, with atomic number 13. Aluminum is a p-element. The outer energy level of the aluminum atom contains 3 electrons, which have the electronic configuration 3s23p1 . Aluminum exhibits an oxidation state of +3.
Belongs to the group of light metals. The most common metal and the third most abundant chemical element in the earth's crust (after oxygen and silicon).
The simple substance aluminum is a light, paramagnetic silver-white metal that can be easily formed, cast, and machined. Aluminum has high thermal and electrical conductivity and resistance to corrosion due to the rapid formation of strong oxide films that protect the surface from further interaction.
Chemical properties of aluminum
Under normal conditions, aluminum is covered with a thin and durable oxide film and therefore does not react with classical oxidizing agents: with H2O (t°); O2, HNO3 (without heating). Thanks to this, aluminum is practically not subject to corrosion and is therefore widely in demand in modern industry. When the oxide film is destroyed, aluminum acts as an active reducing metal.
1. Aluminum easily reacts with simple non-metallic substances:
4Al + 3O2 = 2Al2O3
2Al + 3Cl2 = 2AlCl3,
2Al + 3 Br2 = 2AlBr3
2Al + N2 = 2AlN
2Al + 3S = Al2S3
4Al + 3C = Al4C3
Aluminum sulfide and carbide are completely hydrolyzed:
Al2S3 + 6H2O = 2Al(OH)3 + 3H2S
Al4C3 + 12H2O = 4Al(OH)3+ 3CH4
2. Aluminum reacts with water
(after removing the protective oxide film):
2Al + 6H2O = 2Al(OH)3 + 3H2
3. Aluminum reacts with alkalis
2Al + 2NaOH + 6H2O = 2Na[Al(OH)4] + 3H2
2(NaOH•H2O) + 2Al = 2NaAlO2 + 3H2
First, the protective oxide film dissolves: Al2O3 + 2NaOH + 3H2O = 2Na[Al(OH)4].
Then the reactions occur: 2Al + 6H2O = 2Al(OH)3 + 3H2, NaOH + Al(OH)3 = Na[Al(OH)4],
or in total: 2Al + 6H2O + 2NaOH = Na[Al(OH)4] + 3H2,
and as a result, aluminates are formed: Na[Al(OH)4] - sodium tetrahydroxoaluminate Since the aluminum atom in these compounds is characterized by a coordination number of 6, not 4, the actual formula of tetrahydroxy compounds is as follows: Na[Al(OH)4(H2O) 2]
4. Aluminum is easily dissolved in hydrochloric and dilute sulfuric acids:
2Al + 6HCl = 2AlCl3 + 3H2
2Al + 3H2SO4(dil) = Al2(SO4)3 + 3H2
When heated, it dissolves in acids - oxidizing agents that form soluble aluminum salts:
8Al + 15H2SO4(conc) = 4Al2(SO4)3 + 3H2S + 12H2O
Al + 6HNO3(conc) = Al(NO3)3 + 3NO2 + 3H2O
5. Aluminum reduces metals from their oxides (aluminothermy):
8Al + 3Fe3O4 = 4Al2O3 + 9Fe
2Al + Cr2O3 = Al2O3 + 2Cr
Source: http://himege.ru/alyuminij-xarakteristika-elementa/
Aluminum
ALUMINUM, Al (from the Latin alumen - the name of alum, used in ancient times as a mordant for dyeing and tanning * a. aluminum; n. Aluminum; f. aluminum; i. aluminio), - chemical element of group III of the Mendeleev periodic system, atomic number 13, atomic mass 26.9815. It consists of one stable isotope with a mass number of 27. Discovered by the Danish scientist H. Oersted in 1825.
Physical properties of aluminum
Aluminum is a silvery-white light metal. The aluminum lattice is cubic face-centered with parameter a = 0.40413 nm (4.0413 E).
High purity aluminum (99.996%) is characterized by the following physical properties: density (at 20°C) 2698.9 kg/m3, melting point 660.24°C, boiling point 2500°C, thermal conductivity (at 190°C) 343 W/ m • K, specific heat capacity (at 100°C) 931.98 J/kg • K, electrical conductivity with respect to copper (at 20°C) 65.5%, coefficient of thermal expansion (from 20 to 100°C) 2, 39 • 10-5 deg-1.
Aluminum has low strength (tensile strength 50-60 MPa) and hardness (170 MPa, according to Brinell), but high ductility (up to 50%). Aluminum is highly polished, anodized and highly reflective (90%). Aluminum is resistant to various types of natural waters, nitric and organic acids. When exposed to air, aluminum is coated with a thin, durable film that protects the metal from further oxidation and corrosion.
Aluminum in nature
Aluminum is one of the most common (after oxygen and silicon) elements in the rocks of the earth's crust - 8.8% (by mass). The maximum aluminum content was observed in sedimentary rocks - 10.45% (by mass), the content in medium, basic, acidic and ultrabasic rocks is 8.85%, 8.76%, 7.7%, 0.45% (by mass), respectively. .
There are hundreds of minerals in which it is included as a main or fairly common element. The main carriers of aluminum are aluminosilicates. Minerals with the maximum aluminum content are corundum, gibbsite, boehmite, diaspore. The main source of aluminum is bauxite.
In addition, aluminum is partially extracted from high-alumina alkaline rocks (urtites, etc.) and alunites.
The main feature of the geochemical behavior of aluminum in endogenous processes is its fairly uniform distribution in crystallizing aluminosilicates - feldspars, micas, amphiboles and pyroxenes. It is not typical for post-magmatic and hydrothermal formations. The only unique but rather rare aluminum mineral associated with pegmatites is Na3AlF6 cryolite.
In exogenous processes, aluminum is a very weak migrant due to the high hydrolyzability of its salts with the precipitation of poorly soluble hydroxide Al(OH)3, the low solubility of its other compounds, and the high crystallochemical stability of aluminum-silicon-oxygen radicals in aluminosilicates.
The main concentrator of aluminum in exogenous processes is kaolin, which is formed as a residual product during the weathering of acidic, intermediate and basic rocks. Subsequently, during the erosion and redeposition of kaolinite weathering crusts, aluminum enters sedimentary rocks, mainly clays.
Under particularly contrasting weathering conditions (humid tropics, high ambient temperatures), decomposition in rocks reaches the stage of formation of residual (eluvial) bauxites. There is little aluminum in living organisms and the hydrosphere, although individual organisms are known to be aluminum concentrators (moss mosses, some types of mollusks).
At the same time, in soils and some waters rich in organic matter, a certain migration mobility of aluminum in the form of organomineral compounds is noted. A special mobility of aluminum is established in some volcanogenic-hydrothermal ultra-acidic and acidic solutions. For the main genetic types of deposits and enrichment schemes, see Art. Aluminum ores, bauxites.
Receipt
Metallic aluminum is produced industrially by electrolysis of an alumina solution in molten cryolite or molten AlCl3; A. of high purity (99.996%) is produced by electrolytic refining using the so-called. three-layer method. Fundamentally the same technology, but using organic electrolytes, allows the purity of refined aluminum to be increased to 99.999%.
Application
Due to its lightness, sufficient strength, ability to alloy with many other metals and good electrical conductivity, aluminum is widely used in electrical engineering, as well as as a structural material in mechanical engineering, aircraft manufacturing, construction, etc. Pure and ultra-pure aluminum is used in semiconductor technology and for coating various types of mirrors .
Aluminum is used in nuclear reactors due to its relatively low neutron absorption cross section. Aluminum containers and containers transport liquid gases (methane, oxygen, hydrogen), some acids (nitric, acetic), and store food products, water, and oils. Aluminum is used as an alloying additive in alloys of Cu, Mg, Ti, Ni, Zn, Fe.
In some cases, aluminum is used to make explosives (aluminal, aluminotol, etc.).
Source: http://www.mining-enc.ru/a/alyuminij
History of discovery
In the 16th century, the famous Paracelsus took the first step towards aluminum mining. From alum, he isolated “alum earth,” which contained the oxide of a then unknown metal. In the 18th century, the German chemist Andreas Marggraff returned to this experiment. He named the aluminum oxide “alumina,” which means “astringent” in Latin. At that time, the metal was not popular because it was not found in its pure form.
For many years, English, Danish and German scientists tried to isolate pure aluminum. In 1855, at the Paris World Exhibition, the metal aluminum created a sensation. Only luxury items and jewelry were made from it, since the metal was quite expensive. At the end of the 19th century, a more modern and cheaper method of producing aluminum appeared. In 1911, the first batch of duralumin, named after the city, was produced in Duren.
In 1919, the first airplane was created from this material.
Physical properties
Aluminum metal is characterized by high electrical conductivity, thermal conductivity, resistance to corrosion and frost, and ductility. It lends itself well to stamping, forging, drawing, and rolling. Aluminum can be welded well with various types of welding.
An important property is its low density of about 2.7 g/cm³.
The melting point is about 660°C. The mechanical, physicochemical and technological properties of aluminum depend on the presence and amount of impurities that worsen the properties of the pure metal.
The main natural impurities are silicon, iron, zinc, titanium and copper.
According to the degree of purification, aluminum is distinguished between high and technical purity. The practical difference is the difference in corrosion resistance to certain environments. The purer the metal, the more expensive it is. Technical aluminum is used for the production of alloys, rolled products and cable and wire products.
High purity metal is used for special purposes.
In terms of electrical conductivity, aluminum is second only to gold, silver and copper. And the combination of low density and high electrical conductivity allows it to compete with copper in the field of cable and wire products.
Long-term annealing improves electrical conductivity, while cold hardening worsens it.
The thermal conductivity of aluminum increases with increasing purity of the metal. Impurities of manganese, magnesium and copper reduce this property. In terms of thermal conductivity, aluminum is inferior only to copper and silver.
Due to this property, the metal is used in heat exchangers and cooling radiators.
Aluminum has a high specific heat capacity and heat of fusion. These figures are significantly higher than those of most metals.
The higher the purity of aluminum, the more it is able to reflect light from the surface. The metal is well polished and anodized.
Aluminum has a high affinity for oxygen and is covered in air with a thin, durable film of aluminum oxide. This film protects the metal from subsequent oxidation and provides its good anti-corrosion properties. Aluminum is resistant to atmospheric corrosion, sea and fresh water, and practically does not interact with organic acids, concentrated or diluted nitric acid.
Chemical properties
Aluminum is a fairly active amphoteric metal. Under normal conditions, a strong oxide film determines its durability. If the oxide film is destroyed, aluminum acts as an active reducing metal.
In a finely crushed state and at high temperatures, the metal interacts with oxygen. When heated, reactions occur with sulfur, phosphorus, nitrogen, carbon, and iodine. Under normal conditions, the metal reacts with chlorine and bromine. There is no reaction with hydrogen.
With metals, aluminum forms alloys containing intermetallic compounds - aluminides.
Provided that the oxide film is removed, vigorous interaction with water occurs. Reactions with dilute acids occur easily. Reactions with concentrated nitric and sulfuric acid occur when heated. Aluminum reacts easily with alkalis. Practical application in metallurgy has found the property of reducing metals from oxides and salts - aluminothermy reactions.
Let's look at how various aluminum products are used
Aluminum tape is a thin aluminum strip 0.3-2 mm thick, 50-1250 mm wide, which is supplied in rolls. The tape is used in the food, light, and refrigeration industries for the manufacture of cooling elements and radiators.
Round aluminum wire is used for the manufacture of cables and wires for electrical purposes, and rectangular for winding wires.
Aluminum pipes are durable and resistant in rural and urban industrial areas. They are used in finishing works, road construction, construction of cars, aircraft and ships, production of radiators, pipelines and gas tanks, installation of heating systems, main pipelines, gas pipelines, water pipelines.
Aluminum bushings are characterized by ease of processing, installation and operation. They are used for the end connection of metal cables.
An aluminum circle is a solid round section profile. This product is used for the manufacture of various designs.
Aluminum rod is used to make nuts, bolts, shafts, fasteners and spindles.
About 3 mg of aluminum enters the human body through food every day. The most metal is found in oatmeal, peas, wheat, and rice. Scientists have found that it promotes regeneration processes, stimulates the development and growth of tissues, and affects the activity of the digestive glands and enzymes.
Aluminum sheet
Aluminum plate
Aluminum ingots
Aluminum corners
Aluminum wire
When using aluminum cookware at home, you must remember that only neutral liquids can be stored and heated in it. If, for example, sour cabbage soup is cooked in such a container, then aluminum will enter the food and it will have an unpleasant “metallic” taste.
Aluminum is included in medications used for diseases of the kidneys and gastrointestinal tract.
Source: https://cu-prum.ru/alyuminij1.html
The history of the appearance of aluminum and the first practices of application
The metal, used in almost all spheres of social life, has a relatively short history of development: for the first time in the 16th century, Paracelsus began to solve the problem of its production.
The metal, used in almost all spheres of social life, has a relatively short history of development: for the first time in the 16th century, Paracelsus began to solve the problem of its production. It was he who called aluminum oxide “astringent”, that is, “alumen”.
The work of Paracelsus was continued in the 18th century by Andreas Marggraff; he raised in science the question of the possible properties of aluminum, but was unable to isolate it in its pure form.
How did the first ingot appear?
Humphry Davy, an English scientist, tried to obtain pure aluminum using electrolysis in 1808, and he also gave the substance its modern name. By 1825, in Denmark, Hans-Christian Oersted was able to isolate aluminum chloride, then he obtained a metal whose properties were very similar to those of tin.
The first ingot was the result of 18 years of work by the German scientist Friedrich Wöhler. In all subsequent years, attempts were made to discover cheap ways to obtain pure aluminum.
Since the metal was equal in price to traditional precious metals, French industrialists supplied it to the imperial court for the production of luxury goods and jewelry.
By the end of the 19th century, an American student and a French engineer simultaneously managed to achieve a cheap method of producing aluminum through electrolysis. Since large amounts of electricity were required, the first factories began to be built near the waterfalls.
Australian engineer Bayer made a significant contribution to the history of the development of the aluminum industry: he learned to produce alumina using economical technology, which is still used today. Alfred Wilm increased the strength of aluminum by smelting it with small additions of magnesium, copper and manganese.
By the 20th century, annual aluminum production reached 8 thousand tons.
Modernity: the influence of the aluminum industry on all areas of production
The metal in question is an indispensable component in architecture, advertising production, food industry, construction, design, medicine, etc., in particular, wide aluminum rod for sale (http://www.alfa-sous.ru/4/czvetnoj-metalloprokat/ 14/krug-alyuminievyij.html) occupies a leading position in demand. If we consider the overall prevalence of the substance, only iron is used in industry more than aluminum.
The achievements of the discoverers of the metal are in demand due to the unique properties of aluminum - it is very ductile and has impressive malleability parameters. Thanks to the oxide film, it is not afraid of corrosion, due to which the service life becomes definitely long. Positive properties are also non-toxicity, enhanced electrical conductivity, and ease of processing. Thanks to the advent of aluminum, aircraft and the space industry developed.
The metal still remains quite expensive, so the organization of aluminum recycling is of great importance for global industry. Throughout the country, people constantly bring disused household items, dishes, and wire to collection points for non-ferrous scrap, since the reward calculated for each kilogram is worthy of attention and effort.
Source: http://www.technoflax.com/istoriya-poyavleniya-alyuminiya-i-primenenie.html
Is it better to glaze a balcony with plastic or aluminum?
To turn a balcony or loggia into a full-fledged living room, it should be glazed. This can be done using plastic or lightweight aluminum structures. So that you can choose the appropriate material, we will analyze what is better - glazing balconies with aluminum or plastic.
Main differences
PVC and aluminum are two fundamentally different materials used for glazing loggias and balconies. They differ in weight, frame thickness, cost, and resistance to adverse external factors. To understand which of these options is better, you should study the technical features of each.
Practical advantages of aluminum
Aluminum systems are usually used on balconies and loggias, which do not allow the installation of heavy structures; they allow you to make both cold and warm glazing. They allow you to glaze narrow openings through the use of various opening methods: sliding, rotating. Balcony glazing with lightweight aluminum has a number of advantages, including:
- fast production and installation of the structure;
- low cost of such systems;
- strength and durability of aluminum frames;
- resistance to corrosion, elevated temperatures and high humidity.
It's important to note that aluminum frames are typically made thinner than their plastic counterparts. Thanks to this feature, such systems allow significantly more natural light into the room. This feature is important for those people who want to glaze the balcony on the first floors.
The presented designs also have their drawbacks. These rightly include the high thermal conductivity of the material (frames quickly heat up or freeze in unfavorable weather conditions), as well as the inability to use aluminum for glazing loggias above the 8th floor. Due to their low weight, frames may fall out of the grooves at high heights.
Advantages of PVC
Glazing a balcony or loggia with PVC windows allows you to create a comfortable temperature in the room. Such designs can be used on any floor; they need to be chosen if you want to later convert the balcony into a full-fledged living space. Using PVC windows has a number of advantages, including:
- good sound insulation;
- reliable protection of the premises from drafts and precipitation;
- the ability to use double-glazed windows of different colors, tinted structures, impact-resistant or sun-protective.
It is worth separately considering the disadvantages that PVC double-glazed windows have. These traditionally include the large width of the frame, due to which such products cannot be used on all objects, the large weight of the finished structure, and a higher cost. In addition, PVC products allow less natural light into the home than their aluminum counterparts.
What to choose for a balcony or loggia?
As you can see, there is no clear answer to the question of what is better to glaze a balcony - plastic or aluminum. Each of the presented options has its own advantages. To make the right decision, you need to consider the following features:
- Design dimensions. If your facility allows you to install standard frames, it is better to choose PVC - it makes it easier to create warm glazing. If not, you need to install aluminum.
- Work budget. Installation of aluminum products usually costs customers several times less.
- Wear resistance of products. Over time, aluminum always develops scratches that are almost impossible to remove. PVC also chips, but this material can be easily restored. It is generally less susceptible to negative environmental influences.
- Ease of use. When installed correctly, both types of systems work well and do not cause any inconvenience to their owners.
- Thermal insulation. PVC provides more reliable thermal insulation, in addition, it better protects the room from noise and dust. If you live on a busy street in the city center, you should definitely choose PVC. If your house is located on a quiet street, it is better to choose aluminum. The same applies to the functional purpose of the balcony - if you want to convert it into a living room, you will need to use PVC structures; for other cases, ordinary aluminum windows are suitable.
The service life of the presented products is approximately the same and depends on the correct selection of the type of glazing, as well as the quality of installation.
If you cannot independently determine which double-glazed windows to glaze your balcony, seek help from specialists. They will inspect your facility, determine the basic requirements for this design and choose the best option for you in terms of quality and cost.
Which balcony glazing is better: plastic, aluminum or wood?
Which balcony glazing is better and which windows should you choose so that there are no unpleasant surprises during operation? To answer these extremely important questions, we will consider the advantages and disadvantages of all the main glazing options.
In particular, let's look at:
Let us immediately note that each of the options is good in its own way and has certain strengths. Therefore, it is impossible to definitely name the best glazing for balconies, but you can choose the best option for yourself.
Sliding aluminum window systems
At one time, the PROVEDAL profile was mainly used for the manufacture of aluminum sliding windows. The Spanish company was one of the first to master the market of post-Soviet countries. Now there are an order of magnitude more manufacturers offering this type of product, but so far no one can overtake the PROVEDAL brand in popularity. Although it is worth recognizing that during the crisis, many window companies began to use cheaper analogues in order to beat the competition in price.
Sliding aluminum window systems
Advantages of aluminum windows
The main advantage of sliding aluminum systems is their compactness. In particular, the sashes open parallel to the glazing and, when open, do not cover the floor of the balcony. This is very convenient and practical, especially if the balcony is small or crowded with things.
The second advantage is the minimum weight , which allows you to glaze with aluminum even balconies with a weak load-bearing slab and a flimsy parapet.
And there are quite a lot of them in Russia, since a number of houses were originally built with a thin balcony slab. Over time, she became even weaker.
Well, the third advantage is the low price compared to other types of windows . When every ruble counts, the savings of 30-40% are already more than noticeable and force you to come to terms with some shortcomings.
When ordering aluminum windows, you should know that they can be painted . For painting, a powder mixture and a thermal application method are used, which guarantees safety for many years. Colored designs look much more beautiful, but are also more expensive.
Very few window companies provide such a service. In Moscow, you can order painted aluminum systems with installation from the Glazing-Service company (see prices on their website).
Colored sliding aluminum windows
Weaknesses and obvious shortcomings
The weak side of aluminum glazing can be called the low level of thermal insulation . It will still be cold on the balcony in winter, literally 5-7 degrees more than outside. But high thermal conductivity cannot be called a minus, since many people do not need a warm balcony, because it has its own nuances. However, there are still disadvantages.
In extreme cold, the fittings of aluminum windows often freeze , making it impossible to open/close the sashes. In order for them to start moving, you need to warm them up with warm water, a hairdryer, or otherwise.
You need to take care of the sliding fittings : at least once a year, clean them of any debris and change the lubricant with a new one. Plus, it fails more often and faster than mechanisms on hinged windows.
Sliding plastic window systems
Sliding plastic glazing is similar in technology to aluminum, which we discussed above. The difference is only in a few points:
- Reinforced PVC profile is used for production;
- double-glazed windows are installed;
- more powerful fittings are used, since the weight is much higher.
That is, sliding plastic windows also open parallel to the glazing and are very convenient to use . Plus they provide good thermal insulation and protect against noise from the street . In severe frosts, they freeze in the same way as aluminum ones .
Sliding plastic windows
The disadvantages include high cost , the need for regular maintenance (all sliding fittings are capricious) and considerable weight . It is not recommended to install such structures on weak balconies.
In Russia, the most common systems are SLIDORS and SWS. They are not perfect, of course, but the quality is quite acceptable and they look beautiful. If you don’t know other reputable manufacturers, then it makes sense to look for a window company that supplies them.
Source: https://krovli-zabori.ru/balkony/chem-luchshe-zasteklit-balkon-plastikom-ili-alyuminiem.html
What is aluminum and where is it used?
A hundred years ago, this metal was literally worth its weight in gold and even more expensive, and today kitchen utensils and beer cans are stamped from it.
We are talking, of course, about aluminum, which is gradually approaching steel in terms of its level of use in various industries.
Aluminum - what kind of metal is it?
When it comes to aluminum, the first thing that comes to mind is the unusually light weight of the metal. Indeed, its density is approximately 2.7 g / cubic meter. cm (for comparison: the density of iron is 7.874 g/cubic cm).
In addition, aluminum is the most abundant of all metals and the third most abundant chemical element (the first two being oxygen and silicon). Aluminum accounts for about 8% of the mass of the earth's crust.
A little history
Aluminum became known to mankind quite late: only in the second half of the 19th century, the German chemist Weller managed to isolate pure metal from aluminum chloride by heating its mixture with potassium to a high temperature. But for a very long time, only very wealthy people and rich museums could afford to purchase at least a small piece of silver metal, since the price of a kilogram of aluminum exceeded the cost of an equal amount of gold.
Suffice it to recall the rich gift that British scientists made to the famous creator of the periodic table D.I. Mendeleev. They presented the great Russian chemist with laboratory scales made of aluminum and gold.
How is aluminum obtained?
The main difficulty in obtaining aluminum from ore was the need to heat it to a very high temperature, exceeding 1900 degrees Celsius. For a long time, until the twentieth century, the metal was of no interest to industry, despite all its wonderful qualities, since industrial production remained incredibly expensive and difficult.
Only after powerful industrial power plants were put into operation did the era of mass use of aluminum begin.
The electrolysis method, which requires significant energy consumption, was almost simultaneously proposed by two inventors - the Frenchman P. Héroux and the American C. Hall - back in 1886. With some modifications, it is still used in the aluminum industry today.
The crushed ore is dissolved in molten cryolite, after which the melt is subjected to electrolysis using graphite or coke electrodes.
To obtain one ton of metal, it is necessary to spend approximately 15 MWh of electricity. Is this too much? A multi-story, 100-apartment building consumes approximately the same amount of electricity per month. Therefore, aluminum smelters are always located near large power plants, most often near hydroelectric or nuclear power plants.
Properties of aluminum
The rather high complexity of aluminum production is more than compensated by its excellent properties:
- light weight, almost three times less than steel, which reduces the weight load when making various structures from it;
- excellent ductility, allowing simple stamping to form products of complex shapes from sheet metal;
- corrosion resistance due to the thinnest oxide film that protects its surface from oxidation;
- excellent electrical conductivity, allowing the manufacture of light and cheap wires from it;
- excellent malleability, ease of processing by any means, both in a heated and cold state;
- the ability to form alloys with many metals;
- lack of magnetization.
Parts and elements of various mechanisms, profiled and stamped products, numerous kitchen utensils and household items, medical products, household appliances and much more are made today from aluminum.
However, the metal is very rarely used in its pure form, since its alloys with other metals, as a rule, have much more valuable and necessary properties.
Even a small amount of another metal significantly changes the properties of aluminum.
Today it is widely used in construction, the electronics industry, electrical engineering, aviation, automotive, energy, food industry, mechanical engineering and a number of other equally important industries.
Source: http://www.vseznaika.org/chemiks/chto-takoe-alyuminij-i-gde-ego-primenyayut/
Aluminum metallurgy. How is high purity aluminum obtained? — PCC Group Product Portal
This metal has been well known for more than 2 thousand years and is characterized by wide technical applications. What can it be used for?
In industry, aluminum is mainly used in alloys with other elements, which improves its performance properties. As such, it is a versatile construction material with very versatile applications.
Among aluminum alloys, we can distinguish, in particular, casting alloys and alloys used for plastic processing. In addition to aluminum, they contain elements such as copper, magnesium, silicon and manganese.
Aluminum alloys are used, in particular, in aviation, the chemical industry, automotive industry and even shipbuilding.
Aluminum is widely used in industry in its pure form for the manufacture of various household items, such as, for example, mirrors, cans for drinks and food, kitchen utensils or the well-known aluminum foil.
It is also used for the manufacture of chemical equipment, electrical wires, and even explosives. To isolate this element from bauxite ore, it is necessary to carry out two successive stages. The first of these is the Bayer process, which produces aluminum oxide from the mineral.
This compound is then subjected to electrolysis, resulting in the formation of commercial grade aluminum.
What is aluminum made from?
Pure aluminum does not occur in nature due to its ability to passivate. This phenomenon involves the oxidation of metal in the presence of air, resulting in the formation of a passive protective layer on its surface. Aluminum is coated with a layer of aluminum oxide (Al2O3) up to several nm thick. Then, under the influence of moisture, the outer layer undergoes partial hydrolysis, as a result of which hydroxide is additionally formed, i.e. Al(OH)3.
Aluminum is part of various mineral rocks found in nature in the form of ores. To produce pure aluminum, clayey bauxite ore is used primarily. It is formed mainly in places where aluminosilicate rocks are weathered in hot climates and also contains iron compounds. This is a rock with a characteristic red or brown color, which is found in two types: silicate and carbonate.
Production of technical purity aluminum
Aluminum of technical purity (more than 99%) is industrially produced as a result of two sequential processes. As a result of the first, aluminum oxide is obtained (Bayer process), and at the next stage, an electrolytic reduction process is carried out (Electrolysis by the Hall-Heroult method), due to which pure aluminum is obtained. To reduce the costs associated with transporting bauxite ore, most processing plants are built close to the mines.
Bayer process
The first step after mining the ore is to wash it with water. This removes most of the contaminants that simply dissolve in water. Then, CaO is added to the water-treated raw material, i.e. calcium oxide.
After this, it is crushed using special tube mills until grains with a very small diameter are obtained, i.e. less than 300 microns.
Proper grinding of the raw material is extremely important as it provides a large surface area of the grains, which in turn affects the efficiency of the extraction process.
The next step in the production of aluminum oxide is to dissolve the grains using an aqueous solution of caustic soda. In the PCC Group, sodium hydroxide is produced using membrane electrolysis.
The product thus obtained is characterized by very high quality and purity, while meeting the requirements of the latest edition of the European Pharmacopoeia. The mixture containing ground grains and sodium hydroxide is stored for several hours in special reactors called autoclaves.
During the ongoing deposition process, the reactors are maintained at high pressure and elevated temperature. In this way, sodium aluminate is obtained, which is then purified using various filters.
In the next step, the purified sodium aluminate solution undergoes decomposition. As a result, soda lye (i.e. an aqueous solution of caustic soda) and aluminum hydroxide crystals of high purity are formed. The precipitate obtained as a result of crystallization is filtered off and washed with water. And the remaining soda liquor is heated and returned to the process for reuse.
The final step in the production of pure alumina is calcination. It consists of heating aluminum hydroxide at temperatures above 1000oC, resulting in its decomposition into Al2O3, which is obtained in the form of a pure white powder. Thus prepared aluminum oxide is transported to furnaces to obtain aluminum metal through the process of electrolytic reduction.
Aluminum oxide electrolysis
The next step in obtaining pure aluminum is to carry out the electrolysis process using the Hall-Heroult method. First of all, the Al2O3 obtained in the Bayer process is melted with cryolite and the thus prepared solution is subjected to an electrolysis process at a temperature not exceeding 900oC.
The liquid aluminum thus obtained is separated from the electrolyte and removed from the electrolytic baths using the so-called. vacuum siphons. Then the raw material enters the foundry, from where at a further stage it is put into hot furnaces, in which the processing process takes place.
It involves cleaning aluminum to achieve maximum purity. In industrial conditions, aluminum can be cleaned using two methods. The first involves melting aluminum and passing chlorine through it, causing impurities to bind with the chlorine to form chlorides, which are then removed from the process.
The second method is the electrolytic reduction of aluminum molten with copper. The final product thus obtained is characterized by very high purity.
Aluminum – the material of the future
The development of a method for producing pure aluminum from bauxite using the Bayer process and Hall-Heroult electrolysis expanded the range of applications of this element. In addition, the combination of high strength with lightness has made it possible in some cases to replace more expensive steel with aluminum.
Resistance to atmospheric factors has made it possible to use aluminum in the production of window and door profiles.
Another benefit of aluminum is that it can be recycled many times over, making it a relatively environmentally friendly material.
To summarize, aluminum is a versatile material widely used in the food, energy, chemical, transportation, construction, automotive and aviation industries. Considering its many benefits, this is certainly not the end of its applications and it will continue to gain popularity in the near future.
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Composition and structure of aluminum
Aluminum is the most common metal in the earth's crust. It is classified as a light metal. It has low density and mass. In addition, it has a fairly low melting point. At the same time, it has high ductility and shows good thermal and electrical conductivity characteristics.
Aluminum crystal latticeAluminum structure
The tensile strength of pure aluminum is only 90 MPa. But, if you add some substances to the melt, for example, copper and a number of others, then the tensile strength increases sharply to 700 MPa. The same result can be achieved using heat treatment.
Aluminum, which has extremely high purity - 99.99%, is produced for use in laboratory purposes. For industrial applications, commercially pure aluminum is used. When producing aluminum alloys, additives such as iron and silicon are used. They do not dissolve in the aluminum melt, and the additive reduces the ductility of the base material, but at the same time increases its strength.
Appearance of a simple substance
The structure of this metal consists of simple cells consisting of four atoms. This structure is called face-centric.
Calculations show that the density of pure metal is 2.7 kg per cubic meter.
Properties and characteristics
Aluminum is a metal with a silvery-white surface. As already noted, its density is 2.7 kg/m3. The temperature is 660°C.
Its electrical conductivity is equal to 65% of copper and its alloys. Aluminum and most of its alloys are resistant to corrosion. This is due to the fact that an oxide film forms on its surface, which protects the base material from exposure to atmospheric air.
In the untreated state, its strength is 60 MPa, but after adding certain additives it increases to 700 MPa. The hardness in this state reaches 250 HB.
Aluminum can be easily processed under pressure. To remove work hardening and restore ductility after processing, aluminum parts are annealed, and the temperature should be within 350°C.
The production of aluminum melt, like many other materials, occurs after thermal energy has been supplied to the original metal. It can be supplied either directly into it or from outside.
The melting point of aluminum directly depends on the level of its purity:
-
- Ultra-pure aluminum melts at a temperature of 660.3°C.
- With an aluminum content of 99.5%, the melting point is 657°C.
- With a content of this metal of 99%, the melt can be obtained at 643°C.
Aluminum meltAluminum production process
An aluminum alloy can contain various substances, including alloying ones. Their presence leads to a decrease in the melting point. For example, if there is a large amount of silicon, the temperature can drop to 500°C. In fact, the concept of melting point applies to pure metals. Alloys do not have any constant melting point. This process occurs within a certain heating range.
In materials science there is a concept - solidus and liquidus temperatures.
The first temperature indicates the point at which the melting of aluminum begins, and the second shows at what temperature the alloy will finally melt. In the interval between them, the alloy will be in a mushy state.
Decrease temperature
Before you start melting metal, you can perform certain operations that will reduce the melting temperature. For example, sometimes aluminum powder is melted. In a powdered state, the metal begins to melt somewhat faster.
But with such processing, there is a real danger that when interacting with oxygen contained in the atmosphere, aluminum powder will begin to oxidize with a large release of heat and the formation of metal oxides; this process occurs at a temperature of 2300 degrees.
The main thing is to prevent contact between the melt and water at this moment of melting. This will cause an explosion.
The relatively low melting point of aluminum allows this operation to be carried out at home. It should be noted right away that using a powdered mixture as a raw material in a home workshop is too dangerous. Therefore, either ingots or cut wire are used as raw materials. If there are no special quality requirements for the future product, then anything made from this metal can be used for melting.
Melting aluminum in a homemade forge
In this case, it is not particularly important whether the raw materials are coated with paint or not. When aluminum melts, all foreign substances will simply burn out and be removed along with the slag.
To obtain a high-quality melting result, it is necessary to use materials called fluxes. They are designed to solve the problem of binding and removing foreign impurities and contaminants from the melt.
A home craftsman who decides to melt aluminum at home should be aware that this is a rather dangerous process. And therefore it is impossible to do without the use of protective equipment. In particular, gloves, an apron, and goggles should be used. The fact is that the melt temperature is within 600 degrees. Therefore, it makes sense to use the protective equipment that welders use.
Using protective equipment when melting aluminum
By the way, when melting aluminum and using cleaning chemicals, it is necessary to protect the respiratory system from combustion products.
Selecting a mold for casting
When choosing a mold for casting aluminum, a home craftsman must understand for what purpose he is processing aluminum. If the future casting is intended for use as solder, then there is no need to use any special forms. To do this, you can use a metal sheet on which to cool the molten metal.
But if there is a need to obtain even a simple part, then the master must decide on the type of mold for casting.
The mold can be made from plaster. To do this, gypsum in a liquid state is poured into an oil-treated mold. After it begins to harden, a casting model is installed into it. In order for molten metal to be poured into the mold, a sprue must be formed.
To do this, a cylindrical part is placed in the mold. Forms can be detachable or not. The process of making a split mold is complicated by the fact that the model will be in two halves. After hardening, they are separated, the model is removed and connected again. The form is ready to use.
Aluminum casting die
To obtain high-quality castings, it is advisable to use metal molds (moulds), but it is advisable to produce them only in factory conditions.
Source: https://stankiexpert.ru/spravochnik/materialovedenie/alyuminiy.html
Aluminum: chemical and physical properties
Metals are one of the most convenient materials to process. They also have their own leaders. For example, the basic properties of aluminum have been known to people for a long time. They are so suitable for everyday use that this metal has become very popular. What are the properties of aluminum as a simple substance and as an atom, we will consider in this article.
History of the discovery of aluminum
For a long time, man has known the compound of the metal in question - potassium alum. It was used as a means that could swell and bind together the components of the mixture; this was also necessary in the manufacture of leather products. The existence of aluminum oxide in its pure form became known in the 18th century, in its second half. However, no pure substance was obtained.
The scientist H. K. Ørsted was the first to isolate the metal from its chloride. It was he who treated the salt with potassium amalgam and isolated gray powder from the mixture, which was aluminum in its pure form.
Then it became clear that the chemical properties of aluminum are manifested in its high activity and strong reducing ability. Therefore, no one else worked with him for a long time.
However, in 1854, the Frenchman Deville was able to obtain metal ingots by electrolysis of the melt. This method is still relevant today. Especially mass production of valuable material began in the 20th century, when the problems of generating large amounts of electricity in enterprises were solved.
Today, this metal is one of the most popular and used in construction and the household industry.
General characteristics of the aluminum atom
If we characterize the element in question by its position in the periodic table, then several points can be distinguished.
- The serial number is 13.
- Located in the third small period, third group, main subgroup.
- Atomic mass - 26.98.
- The number of valence electrons is 3.
- The configuration of the outer layer is expressed by the formula 3s23p1.
- The name of the element is aluminum.
- Metallic properties are strongly expressed.
- It has no isotopes in nature; it exists only in one form, with a mass number of 27.
- The chemical symbol is AL, read as “aluminum” in formulas.
- The oxidation state is one, equal to +3.
The chemical properties of aluminum are fully confirmed by the electronic structure of its atom, because having a large atomic radius and low electron affinity, it is capable of acting as a strong reducing agent, like all active metals.
Aluminum as a simple substance: physical properties
If we talk about aluminum as a simple substance, then it is a silvery-white shiny metal. In air it quickly oxidizes and becomes covered with a dense oxide film. The same thing happens when exposed to concentrated acids.
The presence of such a feature makes products made of this metal resistant to corrosion, which, naturally, is very convenient for people. That is why aluminum is so widely used in construction. The properties of the substance are also interesting in that this metal is very light, yet durable and soft. The combination of such characteristics is not available to every substance.
There are several basic physical properties that are characteristic of aluminum.
- High degree of malleability and ductility. Light, strong and very thin foil is made from this metal, and it is also rolled into wire.
- Melting point - 660 0C.
- Boiling point - 2450 0C.
- Density - 2.7 g/cm3.
- The crystal lattice is volumetric face-centered, metal.
- Connection type: metal.
The physical and chemical properties of aluminum determine the areas of its application and use. If we talk about everyday aspects, then the characteristics we have already discussed above play a big role. As a lightweight, durable and anti-corrosion metal, aluminum is used in aircraft and shipbuilding. Therefore, these properties are very important to know.
Regenerative capacity
The reducing properties of aluminum are clearly visible in the reactions of interaction with oxides of other metals. It easily extracts them from the composition of the substance and allows them to exist in a simple form. For example: Cr2O3 + AL = AL2O3 + Cr.
In metallurgy, there is a whole method for producing substances based on similar reactions. It is called aluminothermy. Therefore, in the chemical industry this element is used specifically for the production of other metals.
Distribution in nature
In terms of prevalence among other metal elements, aluminum ranks first. It is contained in the earth's crust 8.8%. If we compare it with non-metals, then its place will be third, after oxygen and silicon.
Due to its high chemical activity, it is not found in pure form, but only as part of various compounds. For example, there are many known ores, minerals, and rocks that contain aluminum. However, it is extracted only from bauxite, the content of which in nature is not very high.
The most common substances containing the metal in question:
- feldspars;
- bauxite;
- granites;
- silica;
- aluminosilicates;
- basalts and others.
In small quantities, aluminum is necessarily found in the cells of living organisms. Some species of club mosses and marine inhabitants are capable of accumulating this element inside their bodies throughout their lives.
Properties of aluminum hydroxide
Hydroxide is the most common compound that aluminum forms. Its chemical properties are the same as those of the metal itself - it is amphoteric. This means that it is capable of exhibiting a dual nature, reacting with both acids and alkalis.
Aluminum hydroxide itself is a white gelatinous precipitate. It is easily obtained by reacting aluminum salts with alkali or ammonium hydroxide. When reacting with acids, this hydroxide gives the usual corresponding salt and water. If the reaction occurs with an alkali, then hydroxo complexes of aluminum are formed, in which its coordination number is 4. Example: Na[Al(OH)4] - sodium tetrahydroxoaluminate.
Source: https://FB.ru/article/190101/alyuminiy-svoystva-himicheskie-i-fizicheskie
Aluminum and its characteristics
Aluminum is the most common metal in the earth's crust. It is a component of clays, feldspars, micas and many other minerals. The total aluminum content in the earth's crust is 8% (mass.).
Aluminum is a silvery-white (Fig. 1) lightweight metal. It is easily drawn into wire and rolled into thin sheets.
At room temperature, aluminum does not change in air, but only because its surface is covered with a thin film of oxide, which has a very strong protective effect.
Rice. 1. Aluminum. Appearance.
Atomic and molecular mass of aluminum
The relative molecular mass of a substance (Mr) is a number showing how many times the mass of a given molecule is greater than 1/12 the mass of a carbon atom, and the relative atomic mass of an element (Ar) is how many times the average mass of atoms of a chemical element is greater than 1/12 the mass of an atom carbon.
Since in the free state aluminum exists in the form of monatomic Al molecules, the values of its atomic and molecular masses coincide. They are equal to 26.9815.
Isotopes of aluminum
It is known that in nature aluminum can be found in the form of one stable isotope 27Al. The mass number is 27. The nucleus of an atom of the aluminum isotope 27Al contains thirteen protons and fourteen neutrons.
There are radioactive isotopes of aluminum with mass numbers from 21 to 42, among which the longest-lived isotope 26Al, whose half-life is 720 thousand years.
Aluminum ions
At the outer energy level of the aluminum atom there are three electrons, which are valence:
1s22s22p63s23р 1.
As a result of chemical interaction, aluminum gives up its valence electrons, i.e. is their donor, and turns into a positively charged ion:
Al0-3e → Al3+.
Aluminum molecule and atom
In the free state, aluminum exists in the form of monoatomic Al molecules. Here are some properties characterizing the aluminum atom and molecule:
| Atom ionization energy, eV | 5,99 |
| Relative electronegativity | 1,61 |
| Atomic radius, nm | 0,143 |
| Standard enthalpy of dissociation of molecules at 25oC, kJ/mol | 329,1 |
Aluminum alloys
The main use of aluminum is the production of alloys based on it. Alloying additives (for example, copper, silicon, magnesium, zinc, manganese) are added to aluminum mainly to increase its strength.
Duralumins containing copper and magnesium, silumins in which the main additive is silicon, magnalium (an alloy of aluminum with 9.5-11.5% magnesium) are widely used.
Aluminum is one of the most common additives in alloys based on copper, magnesium, titanium, nickel, zinc and iron.
Examples of problem solving
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Use of aluminum: areas of application of pure metal and its alloys
Aluminum, as the lightest and most ductile metal, has a wide range of uses. It is resistant to corrosion, has high electrical conductivity, and can easily withstand sudden temperature fluctuations. Another feature is that upon contact with air, a special film appears on its surface, which protects the metal.
All these, as well as other features, contributed to its active use. So, let's find out in more detail what the uses of aluminum are.
This structural metal is widely used. In particular, it was with its use that aircraft manufacturing, rocket science, the food industry and tableware manufacturing began their work. Thanks to its properties, aluminum allows for improved maneuverability of ships due to its lower weight.
Aluminum structures are on average 50% lighter than similar steel products.
Separately, it is worth mentioning the ability of metal to conduct current. This feature made it the main competitor of copper. It is actively used in the production of microcircuits and in the field of microelectronics in general.
The most popular areas of use include:
- Aircraft manufacturing: pumps, engines, housings and other elements;
- Rocket science: as a combustible component for rocket fuel;
- Shipbuilding: hulls and deck superstructures;
- Electronics: wires, cables, rectifiers;
- Defense production: machine guns, tanks, aircraft, various installations;
- Construction: stairs, frames, finishing;
- Railway area: tanks for petroleum products, parts, frames for cars;
- Automotive industry: bumpers, radiators;
- Household: foil, dishes, mirrors, small appliances;
Its wide distribution is explained by the advantages of the metal, but it also has a significant drawback - low strength. To minimize it, copper and magnesium are added to the metal.
As you already understand, aluminum and its compounds are mainly used in electrical engineering (and simply technology), everyday life, industry, mechanical engineering, and aviation. Now we will talk about the use of aluminum metal in construction.
This video will tell you about the use of aluminum and its alloys:
The use of aluminum by humans in the field of construction is determined by its resistance to corrosion. This makes it possible to make structures from it that are planned to be used in aggressive environments, as well as outdoors.
Roofing materials
Aluminum is actively used for roofing production. This sheet material, in addition to its good decorative, load-bearing and enclosing features, also has an affordable price compared to other roofing materials. Moreover, such a roof does not require preventive inspection or repair, and its service life exceeds many existing materials.
By adding other metals to pure aluminum, you can get absolutely any decorative features. This roofing allows you to have a wide range of colors that fit perfectly into the overall style.
Window sashes
You can find aluminum among lanterns and window frames. If wood is used for a similar purpose, it will prove to be an unreliable and short-lived material.
Steel will quickly become covered with corrosion, will have a large binding weight and will be inconvenient to open. In turn, aluminum structures do not have such disadvantages.
The video below will tell you about the properties and use of aluminum:
Aluminum panels are made from alloys of this metal and are used for exterior decoration of houses. They can take the form of ordinary stamped sheets or ready-made enclosing panels consisting of sheets, insulation and cladding. In any case, they retain heat inside the house as much as possible and, being light in weight, do not bear the load on the foundation.
The use of aluminum alloy of different grades deserves a special characteristic.
Alloys are obtained by artificially adding other metals to aluminum in order to obtain the necessary properties. And today there is an endless number of compositions of such alloys that have the widest application.
- The most famous area of their application is aircraft manufacturing. For the production of aircraft, alloys consisting of aluminum, zinc and magnesium are used, which results in a super-strong and reliable material.
- Alloys of aluminum with iron, titanium, and nickel are also often used.
If you want to make something out of aluminum yourself, the following video will tell you how to melt it at home:
Source: http://stroyres.net/metallicheskie/vidyi/tsvetnyie/alyuminiy/ispolzovanie.html
History of aluminum. Description
Aluminum is the most famous and ancient metal. In the form of various clay compounds, it has been known to mankind since time immemorial. Ancient historians testified that “lumen” (translated from Latin as alum) or aluminum-potassium sulfate was used in a variety of fields: both as a mordant for dyeing fabrics and as a fire retardant, and was also used for the manufacture of various household products and decorations
History of production and use of aluminum
In the mid-19th century in Western Europe, scientists desperately tried to obtain aluminum in its pure form. In 1825, Danish explorer H.C. Oersted was the first to carry out a similar experiment using potassium in the form of an amalgam. Unfortunately, it was not possible to accurately determine the resulting substance.
However, two years later, the German scientist Wöhler became interested in obtaining aluminum. He used pure potassium to restore the metal. After 20 years of persistent searching, he managed to obtain pure aluminum in the form of granules the size of a match head. Aluminum turned out to be a beautiful and light metal, similar to silver. These properties of aluminum determined its high cost at that period of history: it was valued more expensive than gold.
At the 1855 Paris Exhibition, aluminum was the main attraction. Aluminum jewelry was placed next to the French crown diamonds. Aluminum has become a very fashionable metal. It was considered a noble element created by nature to create masterpieces of art.
Since the physical and chemical properties of aluminum were poorly studied, jewelers independently invented ways to process it. The softness and pliability of the metal allowed them to create products of any shape, make imprints of intricate patterns, and apply a variety of designs. Aluminum was coated with gold, polished, matted.
However, over time, aluminum began to go out of fashion. In the mid-1860s, a kilogram of this metal already cost only about one hundred old francs, compared to 3 thousand in 1854-1856.
Currently, the first aluminum products are of great value. Unfortunately, fashion fans have replaced most of them with gold, silver and other precious alloys and metals.
However, scientists were not stopped by changing fashion. In 1886, chemist Charles Martin Hall developed a cheap method for producing aluminum in large quantities. He added and dissolved a small amount of aluminum oxide in molten cryolite (a compound of aluminum with sodium and fluorine). Then, placing the mixture in a granite vessel, he passed an electric current through it.
After several hours of waiting, he saw shiny “buttons” of pure aluminum at the bottom of the vessel. The Austrian engineer Karl Joseph Bayer, who was working in Russia at that time, did not stand aside and proposed a technology for producing alumina, which helped make the new method even cheaper.
As a result, Bayer and Hall's version of aluminum production is still used in modern manufacturing today.
Improving the properties of aluminum
The new material, which could now be used in industry, was good for everyone. However, it has been noted that pure aluminum is not strong enough for some applications.
The German chemist Alfred Wilm joined the fight against this problem by alloying it with small amounts of magnesium, copper and manganese. The resulting alloy was so strong that in 1911, a batch of material was produced in the town of Durene, named duralumin in its honor. A little later, in 1919, the first aircraft was made from it. Thus aluminum triumphantly conquered the whole world.
Currently, it is difficult to name an industry that can do without this light silver metal.
Aluminum, which ranks third in concentration in the earth's crust after oxygen and silicon, is attracting the attention of specialists with renewed vigor as the metal of the future.
The combination of its advantages, such as low density, high thermal and electrical conductivity, strength characteristics, as well as high corrosion resistance and manufacturability, make aluminum one of the most valuable materials on the planet.
Source: https://oxi-pro.ru/istoriya-polucheniya-i-primeneniya-alyuminiya
