What is aluminum used for?

How to properly connect copper and aluminum wire

Aluminum electrical wiring can often be found in older buildings. Now everyone understands that this is not the best metal for current. Today, during a major renovation, all the wiring of an old building is usually changed. However, with partial repairs, it becomes necessary to connect aluminum and copper wires.

Is it possible to connect aluminum wires to copper

First of all, you need to return to the school curriculum in chemistry and physics. There is such a thing as a “galvanic cell” - a simple battery that generates electric current. It is formed by the interaction of metals in an electrolyte. Twisting copper and aluminum cable wiring will essentially be the same battery.

Wire connections

Galvanic current quickly destroys metal. Despite the fact that it does not form in dry air, and the twist in the socket will not fall apart in a day, problems are guaranteed when the wiring is used for a long time.

After a few months or years, the wires will begin to deteriorate - this will lead to an increase in resistance. When a powerful current consumer is connected to the outlet, the twist will overheat. If such a connection is used regularly, there is a risk of fire.

Wiring fires

Regulations prohibit the direct twisting of aluminum and copper conductors. However, in emergency situations, the transition must be made, so you need to follow certain rules.

What happens when copper and aluminum come into contact?

Any metal, including copper and aluminum, oxidizes when exposed to oxygen. This leads to the formation of an oxide film on the surface of the material. In the case of copper, it does not prevent the passage of electric current, but the film on aluminum increases its resistance.

If wires are connected, dissimilar metals will begin to interact tightly. Aluminum is considered more active, therefore, when moisture accumulates at the joints (it is present in the air in any case), the process of electrolysis begins, that is, aluminum ions are gradually transferred to copper.

Metal twisting

As a result, one of the conductors loses its mass. Voids and breakdowns form in aluminum - they also oxidize, which speeds up the electrolysis process. The speed of the process also depends on the volume of moisture. Towards the end of the reaction, an almost destroyed aluminum conductor is obtained - its cross-section decreases, and the current density increases. As already described above, the metal heats up and there is a risk of fire.

Rules for connecting copper wires to aluminum

There are safe ways to connect copper and aluminum wires:

Bolted connection

This method is considered the most affordable, reliable and simple. For arrangement you will need:

• Bolt;
• Screw;
• Steel washers (several pieces);
• Wrench.

It is unlikely that it will be possible to use this method to connect wires in an apartment junction box - today they are made too small, and the finished connecting unit is quite large.

However, if a Soviet-era box is installed in the building or you have to work in a distribution panel, then the bolt method is the best solution.

It is considered to be the ideal solution if you have to connect completely incompatible cores - with different cross-sections, from different materials, multi-core/single-core.

Important! The bolt method allows you to connect more than 2 conductors (their number depends on the length of the bolt).

Connection device process:

• Each of the wires will have to be stripped of the insulation layer - 2-3 cm from the edge.
• A ring is assembled from the cleaned ends around the circumference of the bolt so that they can be put on it without any problems.
• Next, a bolt is taken, and a washer is put on it, after which a ring of copper wire, then a second washer, a ring of aluminum conductor, and finally a third washer, the entire resulting structure is tightened with a nut.
• Finally, you need to secure the connection using insulating tape. It is important not to forget that there is an intermediate washer between the aluminum and copper. If you plan to work with several different conductors, then a washer is not necessary between conductors of the same material.

Bolted connection

A special advantage of this method is the versatility of the connection. It can be untwisted and re-twisted at any time and, if you need to add wires, or change the connection diagram.

Terminals

Another cheap and easy connection method is terminal blocks. They are easy to find and buy, especially considering that they are often not sold in whole sections, but are cut in the quantity required for work. The pads come in different sizes, which directly depends on the cross-section of the conductors.

Terminals

Terminal blocks for connecting aluminum and copper wires are a plastic frame with several cells. Inside each is a brass tubular sleeve. The stripped ends of the wires are threaded into the terminal from different sides and clamped with screws. Connection arrangement:

• Loosen the clamp, releasing one part of the sleeve in order to thread the bare part of the wire into the sleeve.
• At the end of the conductor, strip the insulation by 5–6 mm. The wire is inserted into the block, the screw is clamped, fixing the metal to the sleeve. The fastening must be tightened firmly, but not too tightly, otherwise it will break the core.
• Similar steps for connecting a copper wire - only on the opposite side of the terminal.

Important! All stages of work must be carried out sequentially, despite the fact that it is physically possible to loosen both screws, thread the wires and tighten them at once. This is necessary so that the copper and aluminum do not touch ends inside the sleeve.

The main advantage of the terminals is the simplicity of their design and speed of installation. The method is called detachable - one of the conductors can be pulled out without any problems to connect the other.

Lever terminals

The pads are not suitable for working with stranded wires. In this case, you will first have to mount the sleeve tip, which is crimped with a bundle of cores.

Another feature of the terminals is that under screw pressure at room temperature, aluminum sometimes leaks. This leads to the need to regularly check the pads and tighten the contacts. If this is not done, the contact weakens, the connection heats up and sparks - there is a risk of fire.

Wago terminal blocks

A quick and easy connection method - the wires must first be stripped and inserted into the terminals until they stop. There they are automatically fixed using a pressure plate - it strongly presses the material against the tire. The transparent terminal housing allows you to control the passage of the conductor. The problem with this method is the disposability of such devices.

If you need a reusable clamp, then it is better to buy lever terminals. The lever is raised to clear the passage into the hole - the stripped wire is inserted there. The lever is then lowered to lock the wire inside the terminal. This is a detachable connection of copper and aluminum - if necessary, the lever rises to reach the conductor out.

Interesting! WAGO self-clamping devices are very popular and trusted in the market. The company produces a special series of terminals equipped with Alu-plus contact paste. This is a mixture that protects aluminum and copper contacts from corrosion. The model can be distinguished by the special “Al Cu” marking.

Self-clamping structures are very easy to use. The terminal itself indicates how long the core insulation needs to be stripped.

Rivets

Rivets are used to create a permanent connection, which has the same advantages as a threaded connection, but does not require disassembly and reassembly without destroying the rivet and requires a special tool - a connector.

Today, the method is more often used to connect thin-walled elements when forming partitions and the interior of different rooms. Electricians choose rivets because of their low cost, durability, and ease of installation.

Rivets

The principle of installing an electrical connection is simple: a metal rod threaded through a tubular rivet with a head is pulled in and cut. The rod has a thickening - it expands the rivet as it passes through the tube. Retainers come in different lengths and sizes.

Before connecting the wires, they must be prepared in the same way as in the case of a threaded bundle. The diameters of the rings should be slightly larger than the diameters of the rivets - the optimal is 4 mm. An aluminum core is first put on the rivet, then a spring washer, then a copper conductor and a second washer. A steel rod is threaded into the electrical installation and the tool is clamped until it clicks (this is how excess steel is cut off). All is ready.

Connections, both threaded and permanent, are characterized by reliability. This method is used to splice, for example, aluminum wiring damaged during repair work. It is imperative to insulate exposed areas.

Soldering iron

Soldering wires consisting of different metals is a completely feasible solution, if you take into account certain operating rules. Copper does not cause difficulties when soldering, which cannot be said about aluminum. An amalgam is formed on its surface, which is characterized by strong chemical resistance - it does not provide the solder with proper adhesion.

Soldered wires

To work with two dissimilar metal wires, you will have to prepare a solution of copper sulfate, a Krona battery and a piece of copper wire. The future soldering area is carefully cleaned on the aluminum core. Then a solution of copper sulfate is applied to this place.

Copper wiring is connected to the positive pole of the Krona battery and immersed in vitriol solution. An aluminum conductor is connected to the negative pole. After some time, a copper layer will be deposited on the aluminum - solder clings to it without problems.

Adapters for connecting from aluminum to copper

Sleeve adapters for crimping are considered the most reliable and high-quality connection. Special copper-aluminum models are made, into which 2 wires are inserted, after which they are processed with a press. However, it should be noted that the sleeves require sections starting from 16 mm2, while in residential buildings from 1.5 to 4 mm2 are used. Therefore, it is better to connect using a standard aluminum sleeve. Pressure testing occurs according to the following algorithm:

• We strip the ends of the copper conductor with lead-tin solder - this helps prevent metal-to-metal contact.
• Get rid of aluminum oxide film.
• Pass the wires through from different ends and crimp them.
• Wrap the connections with electrical tape or heat shrink followed by heating.

Important! If excessive crimping is done inside the structure, the soldered layer at the copper end may be damaged, so the size of the sleeve and matrix must match the core.

The good thing about the adapter from aluminum to copper is that it can be embedded under the plaster without fear of the wiring catching fire. However, implementation will require a press, which entails certain costs.

Sleeves

It is recommended that when carrying out work, all electrical wiring is intact, without breaks or connections - this reduces the risk of fire. However, if there is an urgent need to join a copper and aluminum core, then you need to take into account all the recommendations and choose one of the most optimal methods.

Source: https://rusenergetics.ru/provoda-i-kabeli/kak-soedinit-medniy-i-alyuminieviy

How to choose the right bike for the city?

The bicycle is a very common and convenient means of transport, which is gaining more and more popularity in large cities.

The reason for this is simple: due to its maneuverability and convenience, a person can easily get from point A to point B without traffic jams and crushes on public transport.

And if you add to this the enormous benefits for the environment and your own health, then this transport becomes one of the best. But to make cycling comfortable and enjoyable, you need to choose it correctly. This is what we will talk about today.

One of the most important advantages of city bicycles is that they do not require regular maintenance. This is partly due to the fact that their key parts and mechanisms are well hidden and protected. At the same time, such models often have headlights, turn signals and signals, which is also very convenient for driving among cars.

This category of bicycles also has a high seating position, which allows you to sit like on a chair and creates a comfortable viewing angle. Such models place a fairly high load on the spine due to their design, and therefore the saddle has special springs at the bottom, which increases riding comfort.

Bicycle frame

The frames of such bicycles can be trapezoidal and without a top tube. Models with an open pipe are much easier to sit down on, which is very important if you are wearing a long coat or skirt (that’s why they are also called women’s). You don't need to raise your leg high when sitting on this bike.

At the same time, in order for the open frame to withstand loads well, it is made more rigid, which is why the weight of the bicycle increases. In this regard, if when choosing a vehicle, the key criteria for you are lightness and maneuverability, then it is better to buy a model with a trapezoidal frame.

It is worth considering that when choosing a closed bicycle, the distance between the body and the pipe should not be less than 10 cm in order to reduce the risk of serious injury in the event of a hard slide.

Material

The strength and lightness of a bicycle depends both on the type of frame design and on the material from which it is made. Today the following materials are distributed:

Aluminum. One of the most popular materials for bicycles with the best price/quality ratio. At the same time, aluminum is quite light, durable and not susceptible to corrosion.

Steel. Another very common material, which is characterized by high strength and long service life. The bikes use chrome plated steel for greater durability and a beautiful appearance.

Carbon. Bicycles made from this material are very light in weight, but also have a high price. Also, carbon is not very durable, so bicycles made from this material are not suitable for high loads.

Depreciation

In urban bicycle models there are two types of shock absorption - rigid and hardtail.

If you are buying a bicycle with the purpose of riding on smooth asphalt roads and are not ready to spend a lot of money, then the best option would be to buy a bicycle without shock absorption or with rigid shock absorption.

If the roads in your city are not always level and smooth, or you prefer to often go outdoors, then it is better to use a hardtail system with a suspension fork. Such models weigh a little more, and the suspension fork itself requires some maintenance, but even the roughest roads will not cause you any discomfort.

A number of models are equipped with a special system (LockOut), which completely blocks the operation of the fork. It can be a great help when you are going uphill and 100% of the force from your leg work is transferred to the rear wheel of the bike.

Saddle

When your riding time does not exceed one hour, and you ride at a relaxed pace and do not plan to make long trips, then the best option would be a soft wide saddle, as well as gel analogues. These models will provide you with the most comfortable ride.

If you are a fan of long bike rides, then you should take a closer look at a hard saddle. In this case, your fulcrum will be the sit bones, and the tissues and blood vessels will not be pinched. When a soft saddle is used for long trips, there is a risk of chafing and pinched blood vessels.

Wheels

The diameter of city bike wheels can vary from 26″ to 28″. Models with a diameter of 28″ are much easier to overcome various kinds of obstacles due to a more optimal angle. On models with similar wheels it is much easier to drive onto a small hill, such as a curb.

However, models with 26″ wheels are more maneuverable and lighter. But the difference between models with different wheels is very small and is practically not felt when driving.

Switching speeds

When there is very little elevation change in the city, a single-speed bicycle is perfect. Such models are lightweight and quite affordable in terms of price. However, shiftable bikes are more suitable for riding on uneven surfaces.

If you are interested in a model with the most reliable gear shift mechanism, then you should take a closer look at bicycles with a built-in planetary hub. In these models, the hub body protects all important parts, which has a beneficial effect on the reliability and durability of the bicycle.

Brakes

There are bicycles with drum brakes, located at the rear of the model in a special sleeve and helping to brake when the pedals rotate backwards. But such a braking system is not always convenient, since it requires a transition from driving to braking, and if the chain falls off, it will be completely useless.

However, mostly city bikes use rim brakes. You just need to press a special lever located on the handlebar, and the brake pads will clamp the bicycle wheel. Such a braking system is more reliable and, if necessary, can be easily repaired.

It is better to purchase a model with rim brakes. This design provides better braking on slippery or wet roads and is safer.

Additional components

There are many additional accessories available for the bike that can be very useful. The cost of the entire kit can reach up to one third of the price of the bike. As a rule, the standard set is the following:

• Multi-hex screwdriver;
• Pump;
• Rear mirror;
• Security lock against theft;
• Bicycle glasses;
• Additional camera;
• Special lubricant for bicycle chain;
• Protective helmet;
• Gloves (this is not necessary, but they make riding much more comfortable).

Prices

• From 120 to 250 dollars. This is an advantage of Chinese models. Such bicycles are not very safe and break down quickly.
• From 250 to 400 dollars. Very budget models that are perfect if you ride a little (up to 2 hours a day).
• From 450 to 750 dollars. Very good bikes that are suitable for those who regularly ride around the city and are used to traveling both on smooth roads and in rural areas.
• From 1,000 to 2,000 dollars. The most expensive category of bicycles. They are used for driving on any terrain, have a long service life and require almost no additional maintenance.

Source: https://cross.expert/sportivnaya-ekipirovka/velosiped-dlya-goroda.html

Properties of aluminum and areas of application in industry and everyday life (page 1 of 4)

Federal Agency for Education of the Russian Federation

State Technological University

"Moscow Institute of Steel and Alloys"

Russian Olympiad for schoolchildren

"Innovative technologies and materials science"

Stage II: Scientific and creative competition

Direction (profile):

«Materials Science and Technologies of New Materials"

ABSTRACT

on the topic of:

«Properties of aluminum and areas of application in industry and everyday life«

I've done the work:

Zaitsev Viktor Vladislavovich

Moscow, 2009

1. Introduction

1.1 General definition of aluminum

1.2 History of aluminum production

2. Classification of aluminum by degree of purity and its mechanical properties

3. Main alloying elements in aluminum alloys and their functions

4. Application of aluminum and its alloys in industry and everyday life

4.1 Aviation

4.2 Shipbuilding

4.3 Rail transport

4.4 Road transport

4.5 Construction

4.6 Petroleum and chemical industries

4.7 Aluminum cookware

5. Conclusion

5.1. Aluminum - the material of the future

6. List of references used

1. Introduction

In my essay on the topic “Properties of aluminum and areas of application in industry and everyday life,” I would like to point out the peculiarity of this metal and its superiority over others. My entire text is proof that aluminum is the metal of the future and without it our further development will be difficult.

1.1 General definition of aluminum

Aluminum ( lat. Aluminium, from alumen - alum) is a chemical element of III gr. periodic table, atomic number 13, atomic mass 26.98154. Silver-white metal, lightweight, ductile, with high electrical conductivity, tmelt = 660 °C. Chemically active (in air it becomes covered with a protective oxide film).

In terms of prevalence in nature, it ranks 3rd among elements and 1st among metals (8.8% of the mass of the earth’s crust). In terms of electrical conductivity, aluminum is in 4th place, second only to silver (it is in first place), copper and gold, which, given the low cost of aluminum, is of great practical importance.

There is twice as much aluminum as iron and 350 times more than copper, zinc, chromium, tin and lead combined. Its density is only 2.7*103 kg/m3 . Aluminum has a face-centered cube lattice and is stable at temperatures from -269 °C to the melting point (660 °C). Thermal conductivity at 24°C is 2.37 W×cm-1×K-1.

The electrical resistance of high purity aluminum (99.99%) at 20°C is 2.6548×10-8 Ohm×m, or 65% of the electrical resistance of the international standard of annealed copper. The reflectivity of the polished surface is more than 90%.

1.2 History of aluminum production

The documented discovery of aluminum occurred in 1825. This metal was first obtained by the Danish physicist Hans Christian Oersted, when he isolated it by the action of potassium amalgam on anhydrous aluminum chloride (obtained by passing chlorine through a hot mixture of aluminum oxide and coal). Having distilled off the mercury, Oersted obtained aluminum, although it was contaminated with impurities. In 1827, the German chemist Friedrich Wöhler obtained aluminum in powder form by reducing hexafluoroaluminate with potassium.

The modern method of producing aluminum was discovered in 1886 by a young American researcher, Charles Martin Hall. (From 1855 to 1890, only 200 tons of aluminum were produced, and over the next decade, using Hall’s method, 28,000 tons of this metal were produced worldwide.) Aluminum with a purity of over 99.99% was first obtained by electrolysis in 1920. In 1925, Edwards published some information about the physical and mechanical properties of such aluminum. In 1938

Taylor, Willey, Smith and Edwards published an article that gives some properties of aluminum with a purity of 99.996%, also obtained in France by electrolysis. The first edition of the monograph on the properties of aluminum was published in 1967. Until recently, it was believed that aluminum, as a highly active metal, could not occur in nature in a free state, but in 1978.

In the rocks of the Siberian platform, native aluminum was discovered - in the form of thread-like crystals only 0.5 mm long (with a thread thickness of several micrometers). Native aluminum was also discovered in lunar soil brought to Earth from the regions of the Seas of Crisis and Abundance. It is believed that aluminum metal can be formed by condensation from gas.

With a strong increase in temperature, aluminum halides decompose, transforming into a state with a lower metal valency, for example, AlCl. When such a compound condenses with a decrease in temperature and the absence of oxygen, a disproportionation reaction occurs in the solid phase: some of the aluminum atoms are oxidized and pass into the usual trivalent state, and some are reduced. Monivalent aluminum can only be reduced to metal: 3AlCl > 2Al + AlCl3.

This assumption is also supported by the thread-like shape of native aluminum crystals. Typically, crystals of this structure are formed due to rapid growth from the gas phase. It is likely that microscopic aluminum nuggets in the lunar soil were formed in a similar way.

2. Classification of aluminum by degree of purity and its mechanical properties

In subsequent years, due to the comparative ease of production and attractive properties, many works on the properties of aluminum were published. Pure aluminum has found wide application mainly in electronics - from electrolytic capacitors to the pinnacle of electronic engineering - microprocessors; in cryoelectronics, cryomagnetics.

Newer methods for obtaining pure aluminum are the zone purification method, crystallization from amalgams (aluminum alloys with mercury) and isolation from alkaline solutions. The degree of purity of aluminum is controlled by the value of electrical resistance at low temperatures.

The following classification of aluminum according to purity level is currently used:

Mechanical properties of aluminum at room temperature:

Pure aluminum is a fairly soft metal - almost three times softer than copper, so even relatively thick aluminum plates and rods are easy to bend, but when aluminum forms alloys (there are a huge number of them), its hardness can increase tenfold. The most widely used:

Beryllium is added to reduce oxidation at elevated temperatures. Small additions of beryllium (0.01 - 0.05%) are used in aluminum casting alloys to improve fluidity in the production of internal combustion engine parts (pistons and cylinder heads).

Boron is introduced to increase electrical conductivity and as a refining additive. Boron is introduced into aluminum alloys used in nuclear energy (except for reactor parts), because it absorbs neutrons, preventing the spread of radiation. Boron is introduced in an average amount of 0.095 - 0.1%.

Bismuth. Metals with low melting points such as bismuth, lead, tin, cadmium are introduced into aluminum alloys to improve machinability. These elements form soft, fusible phases that contribute to chip brittleness and cutter lubrication.

Gallium is added in an amount of 0.01 - 0.1% to the alloys, from which consumable anodes are then made.

Iron. It is introduced in small quantities (»0.04%) in the production of wires to increase strength and improve creep characteristics. Iron also reduces adhesion to the walls of molds when casting in a chill mold.

Indium. An addition of 0.05 - 0.2% strengthens aluminum alloys during aging, especially with low copper content. Indium additives are used in aluminum-cadmium bearing alloys.

Approximately 0.3% cadmium is introduced to increase the strength and improve the corrosion properties of the alloys.

Calcium imparts plasticity. With a calcium content of 5%, the alloy has the effect of superplasticity.

Silicon is the most used additive in foundry alloys. In an amount of 0.5 - 4% it reduces the tendency to cracking. The combination of silicon and magnesium makes it possible to heat seal the alloy.

Magnesium. The addition of magnesium significantly increases strength without reducing ductility, increases weldability and increases the corrosion resistance of the alloy.

Copper strengthens alloys, maximum strengthening is achieved with a copper content of 4 - 6%. Copper alloys are used in the production of pistons for internal combustion engines and high-quality cast aircraft parts.

Tin improves cutting performance.

Titanium. The main task of titanium in alloys is to refine the grain in castings and ingots, which greatly increases the strength and uniformity of properties throughout the entire volume.

Aluminum is one of the most common and cheapest metals. It is difficult to imagine modern life without it. No wonder aluminum is called the metal of the 20th century. It lends itself well to processing: forging, stamping, rolling, drawing, pressing.

Pure aluminum is a fairly soft metal; It is used to make electrical wires, structural parts, food foil, kitchen utensils and “silver” paint. This beautiful and lightweight metal is widely used in construction and aviation technology. Aluminum reflects light very well.

Therefore, it is used to make mirrors - by depositing metal in a vacuum.

Source: https://mirznanii.com/a/325500/svoystva-alyuminiya-i-oblasti-primeneniya-v-promyshlennosti-i-bytu

2.2.3. Characteristic chemical properties of aluminum

Aluminum is an amphoteric metal. The electronic configuration of the aluminum atom is 1s22s22p63s23p1. Thus, it has three valence electrons on its outer electron layer: 2 on the 3s and 1 on the 3p sublevel. Due to this structure, it is characterized by reactions as a result of which the aluminum atom loses three electrons from the outer level and acquires an oxidation state of +3. Aluminum is a highly reactive metal and exhibits very strong reducing properties.

with oxygen

When absolutely pure aluminum comes into contact with air, aluminum atoms located in the surface layer instantly interact with oxygen in the air and form a thin, tens of atomic layers thick, durable oxide film of Al2O3 composition, which protects aluminum from further oxidation. It is also impossible to oxidize large samples of aluminum even at very high temperatures. However, fine aluminum powder burns quite easily in a burner flame:

4Al + 3O2 = 2Al2O3

with halogens

Aluminum reacts very vigorously with all halogens. Thus, the reaction between mixed aluminum and iodine powders occurs already at room temperature after adding a drop of water as a catalyst. Equation for the interaction of iodine with aluminum:

2Al + 3I2 =2AlI3

Aluminum also reacts with bromine, which is a dark brown liquid, without heating. Simply add a sample of aluminum to liquid bromine: a violent reaction immediately begins, releasing a large amount of heat and light:

2Al + 3Br2 = 2AlBr3

The reaction between aluminum and chlorine occurs when heated aluminum foil or fine aluminum powder is added to a flask filled with chlorine. Aluminum burns effectively in chlorine according to the equation:

2Al + 3Cl2 = 2AlCl3

with sulfur

When heated to 150-200 °C or after igniting a mixture of powdered aluminum and sulfur, an intense exothermic reaction begins between them with the release of light:

- aluminum sulfide

with nitrogen

When aluminum reacts with nitrogen at a temperature of about 800 oC, aluminum nitride is formed:

with carbon

At a temperature of about 2000oC, aluminum reacts with carbon and forms aluminum carbide (methanide), containing carbon in the -4 oxidation state, as in methane.

with water

As mentioned above, a stable and durable oxide film of Al2O3 prevents aluminum from oxidizing in air. The same protective oxide film makes aluminum inert towards water. When removing the protective oxide film from the surface by methods such as treatment with aqueous solutions of alkali, ammonium chloride or mercury salts (amalgiation), aluminum begins to react vigorously with water to form aluminum hydroxide and hydrogen gas:

2Al + 6H2O = 2Al(OH)3 + 3H2

with metal oxides

After igniting a mixture of aluminum with oxides of less active metals (to the right of aluminum in the activity series), an extremely violent, highly exothermic reaction begins. Thus, in the case of interaction of aluminum with iron (III) oxide, a temperature of 2500-3000°C develops. As a result of this reaction, high-purity molten iron is formed:

2AI + Fe2O3 = 2Fe + Al2O3

This method of obtaining metals from their oxides by reduction with aluminum is called aluminothermy or aluminothermy.

with non-oxidizing acids

The interaction of aluminum with non-oxidizing acids, i.e. with almost all acids, except concentrated sulfuric and nitric acids, leads to the formation of an aluminum salt of the corresponding acid and hydrogen gas:

a) 2Al + 3H2SO4(dil.) = Al2(SO4)3 + 3H2

2Al0 + 6H+ = 2Al3+ + 3H20;

b) 2AI + 6HCl = 2AICl3 + 3H2

-concentrated sulfuric acid

The interaction of aluminum with concentrated sulfuric acid under normal conditions and at low temperatures does not occur due to an effect called passivation. When heated, the reaction is possible and leads to the formation of aluminum sulfate, water and hydrogen sulfide, which is formed as a result of the reduction of sulfur, which is part of sulfuric acid:

Such a deep reduction of sulfur from the oxidation state +6 (in H2SO4) to the oxidation state -2 (in H2S) occurs due to the very high reducing ability of aluminum.

- concentrated nitric acid

Under normal conditions, concentrated nitric acid also passivates aluminum, which makes it possible to store it in aluminum containers. Just as in the case of concentrated sulfuric acid, the interaction of aluminum with concentrated nitric acid becomes possible with strong heating, and the reaction predominantly occurs:

- dilute nitric acid

The interaction of aluminum with diluted nitric acid compared to concentrated nitric acid leads to products of deeper nitrogen reduction. Instead of NO, depending on the degree of dilution, N2O and NH4NO3 can be formed:

8Al + 30HNO3(dil.) = 8Al(NO3)3 +3N2O + 15H2O

8Al + 30HNO3(ultra dilute) = 8Al(NO3)3 + 3NH4NO3 + 9H2O

with alkalis

Aluminum reacts both with aqueous solutions of alkalis:

2Al + 2NaOH + 6H2O = 2Na[Al(OH)4] + 3H2

and with pure alkalis during fusion:

In both cases, the reaction begins with the dissolution of the protective film of aluminum oxide:

Al2O3 + 2NaOH + 3H2O = 2Na[Al(OH)4]

Al2O3 + 2NaOH = 2NaAlO2 + H2O

In the case of an aqueous solution, aluminum, cleared of the protective oxide film, begins to react with water according to the equation:

2Al + 6H2O = 2Al(OH)3 + 3H2

The resulting aluminum hydroxide, being amphoteric, reacts with an aqueous solution of sodium hydroxide to form soluble sodium tetrahydroxoaluminate:

Al(OH)3 + NaOH = Na[Al(OH)4]

Source: https://scienceforyou.ru/teorija-dlja-podgotovki-k-egje/himicheskie-svojstva-aljuminija

The role of aluminum in the human body. Sources, benefits and harm

Aluminum is part of all organs and systems of the human body. It is necessary to ensure most reactions affecting the formation of protein and phosphate compounds.

The element is also involved in other important processes, therefore it is included in the set of vitamins and minerals essential for humans. But its intake must be controlled, since in high concentrations aluminum becomes toxic.

The meaning and benefits of aluminum for humans

In combination with other components, aluminum supports the following processes in normal condition:

• active regeneration of damaged cells;
• formation of tissues of the musculoskeletal system and skin;
• activation of digestive enzymes and gastric juice;
• increasing the body's sensitivity to absorb proteins;
• maintaining the natural cycle of the thyroid gland.

The beneficial properties of the microelement make it an indispensable supplement for people with diseases such as osteoporosis and bone fractures, ulcers, gastritis.

Symptoms of micronutrient deficiency

In medical practice, there are practically no cases where aluminum deficiency was found in the body of patients. This is due to its high digestibility and presence in many store products. However, laboratory studies conducted on animals have identified possible symptoms of aluminum deficiency:

• weakened muscles, bones and joints;
• loss of motor activity, general weakness;
• slow recovery from physical damage;
• problems with coordination;
• miscarriages;
• weakening of cognitive abilities.

The microelement is of particular importance for children, whose bodies are developing and need sufficient amounts of aluminum. If there is too little of it, physical and mental development is delayed.

Aluminum deficiency develops against the background of an insufficiently rich diet: lack of vegetables and fruits, cereals on the menu, prolonged consumption of the same food.

Excess microelement in the body is very dangerous for health.

When it enters the blood, aluminum spreads throughout all systems, affecting them. In large quantities, aluminum acts on cells as a carcinogen. Without giving it to them, it's okay to share. The cells begin to multiply randomly, which can lead to serious complications.

Causes and symptoms of excess element

You can get an excessive amount of aluminum (over 50 mg) per day in the following cases:

• work in production involving the use of aluminum compounds;
• constant use of uncoated aluminum utensils (spoons, plates and forks), as well as long-term storage of food in aluminum containers, including tetra packs with foil inside;
• regular use of aluminum-based medications;
• the use of decorative cosmetics with aluminum salts and other compounds that contain a metal molecule;
• the presence of acute renal failure - during the disease a malfunction occurs, and the accumulation of salts of the element increases in the body;
• excessive consumption of foods with a high content of microelements;
• consumption of store-bought semi-finished products and some factory-made dishes with preservatives (aluminum sulfates and salts: E520, E521, E522, E523);
• Regularly drinking water rich in aluminum compounds.

It is impossible to determine exactly in which city the risk of aluminum poisoning is higher. However, there are areas where people receive much more of the mineral by inhaling it in the air (places where aluminum processing plants and other metallurgical enterprises are located).

Symptoms of trace element excess

Excessive consumption of aluminum compounds in food causes conditions such as:

• moderate to severe cough,
• loss of appetite,
• increased nervousness,
• digestive problems,
• disorientation,
• kidney diseases.

People with elevated metal concentrations in the blood experience a decrease in the number of red blood cells and hemoglobin levels.

With prolonged accumulation of aluminum in the body, memory loss, depression, and the development of Alzheimer's disease in adulthood are possible. In case of acute intoxication over a long period of time, severe disorders may occur:

• seizures and convulsions, arthritis and rickets;
• softening of bone tissue and subsequent problems with the musculoskeletal system, permanent fractures;
• encephalopathy, manifested by mental problems and depression;
• acute disorders of the central nervous system;
• insufficient levels of magnesium, copper, zinc, iron, calcium and phosphorus.

Aluminum suppresses the activity of the immune system, and constant exposure to high doses of the body greatly reduces human life expectancy.

Aluminum in food

With water and food, a person receives fairly high doses of aluminum every day, but no more than 4% is absorbed from them. Water is enriched with aluminum in places where purification is carried out using potassium alum. Increased levels of the mineral in the liquid are also found where acid rain occurs regularly.

Plant foods contain several times more minerals than meat and animal products. An additional source of aluminum is utensils made from this metal, especially those not coated with protective substances. Under the influence of temperature, metal from foil, dishes, and cutlery can pass into the processed food. But it is not destroyed in food.

Fact! Yeast contains aluminum compounds. In combination with the forms used for baking, this factor increases the metal concentration in bread several times.

Processed cheese is a separate product, the production of which uses chemical melters. They contain aluminum compounds. Fortified with preservatives, they increase the microelement content in cheese, despite the fact that it is a product of animal origin.

Plant sources of aluminum:

• the least is found in apples and lentils - from 0.11 to 0.17 mg;
• in cucumbers, grapes and carrots – from 0.323 to 0.42 mg;
• in corn, cabbage, semolina - from 0.425 to 0.57 mg;
• in beans, peaches, kiwi, savoy cabbage, eggplant, avocado, Jerusalem artichoke - from 0.6 to 0.815 mg;
• in potatoes and rice – from 0.86 to 0.91 mg;
• premium, 1st and 2nd grade flour contains 1.05-1.4 mg;
• Rye, wheat and sorghum contain the most aluminum - from 1.5 to 1.67 mg;

People should pay special attention to bread bought in stores. Even if it is a super-healthy gray loaf with bran, it will contain an exorbitant amount of aluminum. And the absence of yeast does not compensate for this factor. Thus, it is not recommended for anyone to get involved in any kind of baking. Even if a person does not follow a low-calorie diet.

Interaction with other elements

When using aluminum cookware, you need to remember that the release of metal ions is activated when an unprotected surface interacts with acids (lemon juice, vinegar, any citrus fruits).

Important! Aluminum compounds taken in large quantities block the absorption of vitamin C, sulfur-containing amino acids, vitamin B6, calcium, iron and magnesium.

Phosphorus absorption deteriorates if large doses of aluminum are constantly present in the diet. At the same time, magnesium is able to neutralize metal compounds; ions of silver, iron, calcium and copper have similar properties.

Daily consumption rate

There are no exact studies establishing the norm for different ages. But it is known that consuming less than 0.001 mg of aluminum per day can lead to a deficiency of the trace element. A dosage of 50 mg is considered critical. Due to the prevalence of aluminum in industry, it is more difficult to control not the deficiency, but the excess of the element.

An overdose of metal does not manifest itself immediately; for this to happen, a lot of aluminum reserves must accumulate in the body. Therefore, the consequences of intoxication are observed only several years after a person began to regularly receive large doses of the metal (with food, water or air).

The effect of aluminum on pregnancy

There have been no human studies regarding the effects of aluminum on the fetus or pregnant woman. But laboratory tests on animals have established that high dosages of the metal lead to its accumulation in fetal tissues. And this is fraught with many violations:

• delayed embryo development;
• slow skeletal formation;
• malformations of organs and systems;
• miscarriage;
• intrauterine death.

Newborns are highly sensitive to aluminum, so the mother is potentially prohibited from taking medications for gastritis, ulcers, or other drugs containing aluminum.

Aluminum in medicine and cosmetology

Metal compounds have been used in medicine for a long time - the first mentions can be traced back to the 15th century. At that time, aluminum alum was used by the Slavs to heal skin wounds. Aluminum compounds are widely used in the production of deodorants: these substances clog pores, but in the form of salts they can be deposited in the body.

Fact! You can find metal in wet wipes and towels.

The most popular medications with a high aluminum content are drugs for gastritis, ulcers and heartburn (“Alumag”, “Almagel”, “Antacid”, “Gastal”, “Alyugastrin”). Tablets packed in blisters and in contact with aluminum foil may contain traces of metal ions in the composition.

Aluminum is a trace element that does not top the lists of vitamins and minerals necessary for human health. But in low dosages it is beneficial for the body.

However, to obtain them there is no need to use special supplements or introduce foods high in metal into the diet.

On the contrary, most often it is necessary to limit its supply - the food industry has made sure that, along with semi-finished products and canned food, people receive large doses of the mineral.

Source: https://polzaili.ru/rol-alyuminiya-v-organizme-cheloveka-istochniki-polza-i-vred/

How to set up iPhone 11 after purchase - instructions

We help you figure out iPhone 11. Pros and cons of the smartphone, new features. How to set up your phone.

The strengths and weaknesses of the iPhone 11 are shown in the table:

Advantages	Flaws
Improved display on Pro and Pro Max models. The well-known and beloved OLED matrix has been modernized: support for HDR formats has been added and contrast has been increased. Thanks to the improvements, the image is bright and at the same time does not “hurt” the eyes, and does not fade even under the influence of direct sunlight.	Small amount of integrated memory. Many companies, including Chinese ones, have raised the minimum built-in storage limit to 128 GB and higher, but Apple has remained at 68 GB. Moreover, it is impossible to purchase and place a removable memory card - there is no space for it.
Increased productivity. It is provided by the most powerful A13 Bionic processor, a revised machine learning system and a three-module camera.	Save on USB-C. Despite the anticipation after the release of the iPad Pro, fast charging was never included in the box for the iPhone, even though it is compatible with it. Its cost exceeds 5 thousand rubles.
Faster GPU. He is twenty percent more productive than the last one.	No reverse charging. Almost all analysts were confident that after updating the Samsung Galaxy, Apple would not want to lag behind its main competitor and would also introduce technology to “power” other gadgets from the smartphone. But, unfortunately, this did not happen.
Longer battery life. It is guaranteed by a battery with a capacity of more than 3 thousand mAh and has reached 86 hours, which is 4 hours longer.
More modern protection against water and dust. iPhone 11 retains its functionality when immersed in water up to two meters for thirty minutes, as it uses the IP68 standard. Previous models used less serious IP67 standards.

Separately, we should dwell on the new “chips” of the iPhone 11. These include:

1. New colors. Apple lovers can choose the iPhone 11 in one of the following shades: white, black, red, yellow, green and purple.
2. 3D glass. The iPhone 11 case is made of anodized aluminum, which seems to “flow” into 3D glass, creating a stunning visual effect.
3. More cameras. The iPhone 11 has two, while the Pro and Pro Max models have three. The main camera is twelve megapixel, with several shooting modes and autofocus and other options. The secondary camera features an ultra-wide-angle lens that lets you feel like a true filmmaker.
4. Slow motion selfie. It is possible to do slowmo on iPhone 11. To do this, you need to go to “Camera”, switch to the front camera and switch to slow-motion selfie mode. Then all that remains is to show your imagination.
5. Detailed photographs. iPhone 11 captures four primary and four secondary images before you even touch the shutter. As a result, the image is drawn “pixel by pixel”.
6. Night mode. With iPhone 11, you can take beautiful photos even when it's dark. Night mode starts to activate independently and does not require turning on the flash. Areas with blur and noise are removed from the image. In addition, the picture is detailed.
7. Adjusting the sound strength. Let's say you're filming a person saying something. His voice will be louder than everything else (ads coming from stores, noise made by special equipment, etc.).
8. Play music using surround sound technology. The speakers work based on spatial audio.
9. Support for Wi-Fi 6. The eleventh iPhone was the first smartphone to support Wi-Fi 6. This means that Internet speed has increased.

First launch of the smartphone

To start the device for the first time, you only need to press one button - the one located on the side. Keep your finger on it until the Apple logo appears and a greeting appears in the most popular languages ​​of the world. Follow the instructions.

If you have very poor vision, use the VoiceOver or Zoom function.

You will be offered several languages. Choose one of them.

You will also need to decide on a country and a more specific location. Indicate your current location, as the display of date, time, contacts, etc. depends on it.

Activation and setup of iPhone 11

Activation of iPhone 11 can be done through:

1. Wi-Fi.
2. Mobile network.
3. iTunes.

You must first insert a SIM card. It is allowed to use both existing and new ones.

As for setting up iPhone 11, it is best done through “Quick Start”. True, there is one “but”: this method is only suitable for those who have an iPhone or iPad of a previous model. The process looks like this:

1. Insert a SIM card into the new device. It is convenient to get it out with a special device included in the kit, but you can also cope with the task using a regular small paper clip.
2. Turn on both mobile phones and place them next to each other. Both the first and the second must have the iOS operating system no lower than version eleven installed.
3. You notice the inscription “Quick start” on the old device, after which you check the identifier and click on the word “Continue”. If there is no “Quick Start” sign on your old device, then the problem is either Bluetooth not turned on or outdated iOS.
4. Wait for the animation on your new mobile phone and perform automatic (via the viewfinder) or manual authentication.
5. Provide the password code from the old device to the new mobile phone.
6. Enter your Apple ID on your new device.

Setting up an iPhone 11 takes anywhere from two minutes to several hours, depending on the amount of data and Internet speed.

Do not forget that during synchronization you cannot block Internet access and turn off chargers.

More details about setting up iPhone 11 are described in the video

How to create an Apple ID

Source: https://tarifkin.ru/mobilnye-sovety/kak-polzovatsya-ajfonom-11