Bura in agriculture. The use of drills for borating steel. The use of borax in the melting of metals as a protective cover

Borax (sodium borate) - crystals, melting point of borax - t pl = 60.8°C.

In nature, it is a mineral of the borate class, a chemical sediment of drying up boron-bearing salt lakes.

Borax crystals are transparent, colorless or grayish, have a greasy sheen, soluble in water (1 tsp in 14 tsp of water); taste - sweetish-alkaline.

Chemical composition - Na 2 B 4 O 7 +10H 2 O corresponds to 16% sodium, 37% boric acid and 47% water.

Borax is deposited in large quantities along the edges of the Tibetan self-planting salt lakes, from where it was first imported to Europe, under the local name tinkala.

Of other deposits, some small lakes of California should also be indicated, in particular, the shallow lake " Cleare”, in the silt of which large borax crystals are found.

Other deposits: Kashmir, Nevada desert, etc.

Borax is a raw material for the production of boric acid and other boron compounds, a component of fluxes for welding metals, charge in the production of glazes, enamels, glass, detergents, electrolytes in metallurgy, an insecticide, an antiseptic, a preservative in the processing of leather, etc.

5 easy ways to use borax

1. Toilet bowl cleaner

Pour 1 cup of borax down the toilet and leave overnight. The next morning, scrub the toilet with a brush. During the night, the borax will dissolve all stubborn layers.

Borax also does a good job of removing rust.

2. Flea control

Sprinkle borax in places where dogs usually sleep (litters, carpets) and generally anywhere you suspect fleas nest.

Borax releases boric acid, which is a poison (in order to harm an animal or a person, you need to swallow very large doses of this substance).

3. Mold control

This method is good to use in places where you need to remove mold and mildew, but where you do not have to worry about peeling off the paint.

Make a paste of borax and water (thick enough). Spread it on the moldy surface. Leave overnight or longer.

Sweep away the dried powder, rinse the rest with water.

4. Repel mice

Sprinkle borax on the floor along the walls.

5. All-purpose detergent.

Mix 2 teaspoons of borax with 2 cups of water. Pour into a spray bottle.

Shake before use.

BURA(sodium tetraborate decahydrate Na 2 B 4 O 7 10 H 2 O) - large colorless crystals, soluble in water, which erode from the surface in dry air and melt at 61 ° C, at 320–380 ° C it loses crystallization water. Anhydrous sodium tetraborate is a colorless crystalline substance with a density of 2.367 g / cm3, melts at 741 ° C without decomposition. Thermally unstable sodium tetraborate becomes only at 1575 ° C. The solubility coefficient (in g per 100 g of water) is 2.5 (at 20 ° C) and 24.3 (at 80 ° C).

In nature, borax is found mainly in water and bottom sediments of some lakes. Such lakes are not uncommon in India and Tibet; natural borax from those places is the mineral tinkal. In medieval times, the borax mined here was loaded into bags made of elephant skins and taken to Venice, where it was purified from impurities by crystallization from an aqueous solution. The methods of obtaining borax were kept in the strictest confidence; even European alchemists did not know them.

However, alchemists distinguished borax from soda, although exactly how they did this is not known: after all, both substances are similar in that they give an alkaline environment when dissolved in water and therefore displace ammonia from ammonium chloride.

The alkaline reaction of a solution of sodium tetraborate is due to the fact that in aqueous

solution, a hydrolysis reaction proceeds with the formation of boric acid B (OH) 3 in a solution:

Na 2 B 4 O 7 \u003d 2Na + + B 4 O 7 2–;

B 4 O 7 2– + 7H 2 O 2OH – + 4B(OH) 3,

and the release of ammonia upon interaction with NH4Cl corresponds to the equation:

Na 2 B 4 O 7 + 2NH 4 Cl + H 2 O \u003d 2NH 3 + 2NaCl + 4B (OH) 3 Ї

Although in the 16-17 centuries. chemists had no idea about the exact composition of the substances they received and used, and their properties were judged by the most primitive signs, such as a taste test, they were sometimes able to make remarkable discoveries. So, the Dutch alchemist Wilhelm Gomberg, heating borax with sulfuric acid H 2 SO 4, isolated boric acid B (OH) 3.

In this case, the following reaction took place:

Na 2 B 4 O 7 10H 2 O + H 2 SO 4 \u003d B (OH) 3 Ї + Na 2 SO 4 + 5H 2 O

And in 1751, Henri Duhamel de Monceau found that borax, like soda, contains the element "sodium" ... One can only guess how exactly three thousand years BC people came across borax. It is possible that a Hindu pilgrim, while resting on the shore of a lake, threw a piece of an unknown white substance into the fire and noticed that the flame turned green, and the substance melted and became like glass... The priests of Ancient Egypt, who knew how to make the flame of lamps green. Later, they probably discovered that borax, like soda, helps to wash clothes from dirt (there was no soap yet). Gradually, people learned to use borax for tanning leather, in the production of glass and glazes, and finally, as a medicine - an antiseptic for washing the throat. The first mention of a storm in Russia is found in 1709 in the account book. Order of Ore Affairs. In the affairs of Peter I, a note was found about the need to obtain borax from Russian natural sources, of which there were many. Nevertheless, borax was imported to Russia from Venice and from England for a long time.

Currently, borax is used very widely: it is an antiseptic and preservative, mordant (pre-impregnation) for dyeing fabrics, raw materials for the production of boric acid, herbicides, corrosion inhibitors (inhibitors), detergents (water softener). In addition, borax serves as one of the components of the charge (the initial mixture of substances) in the production of glazes, glass and ceramics.

Every jeweler is accustomed to dealing with borax - it is an indispensable component of fluxes when welding and soldering precious metals (gold and silver).

Ludmila Alikberova

It is carried out by first removing traces of oxides from their surface. Fluxes are used for this. They should prevent oxidation when heated and encourage good flow of the molten solder.

For soldering copper products, borax solder is ideal for all requirements. The substance has been known since the Middle Ages. It was mined in the lakes of India, Tibet, then transported to Europe, where it was used for processing fabrics and leather, and for the production of glasses.

Borax is widely used for working with metals. In the manufacture or repair of metal products, soldering is carried out with brown. First of all, the method is used for parts made of copper, brass. A special variety of this flux is used in the repair of jewelry.

The exact origin of the historically established, trivial name has not been finally clarified. According to the chemical nomenclature, borax is a crystalline hydrate of the sodium salt of tetraboric acid.

If the composition includes 10 water molecules, then the substance is called sodium tetraborate decahydrate. There are types of crystalline hydrate with five water molecules.

They are called sodium tetraborate pentahydrates. Strictly speaking, the composition of borax is a salt surrounded by a hydration shell of 10 dipoles of water.

At 64℃, the decahydrate melts, gradually loses water. Complete dehydration of borax occurs at 380°. The resulting tetraborate withstands heating up to 742° and only then melts.

Such a gradual melting of borax somewhat confuses ordinary consumers who are accustomed to the fact that the substance melts strictly at one temperature. The specificity is explained by the presence of water molecules in the crystalline hydrate. This feature simplifies the use of borax for soldering.

The quality of the substance is normalized by the state standard. There are two brands of raw materials, which are technical borax:

• Grade A is 99.5% salt decahydrate. The remaining 0.5% consists of carbonates, sulfates, a meager amount of lead and arsenic compounds;
• grade B - 94% decahydrate, the content of impurities in which is 6%.

Both brands are not very stable. The shelf life of technical borax should not exceed six months. It is recommended to use brand B borax as a flux. It fully meets the requirements of soldering, it costs less than brand A raw materials.

Advantages and disadvantages

Borax based flux is very popular. This item is always on sale. For soldering copper products, borax is the most affordable flux that has budget prices.

Borax is also used for soldering some types of steels, jewelry alloys. Solders containing copper or silver are suitable for the process. Solder seams, if necessary, can always be simply soldered.

Depending on the elemental composition of the parts, it is possible to use not only crystalline powder, but also a solution. The crystalline hydrate is highly soluble in water.

There are some difficulties when using borax. The place of the solder after soldering is covered with a coating. It must be mechanically cleaned.

The shelf life of the material is limited, it must be stored in a dry place. Despite this, borax remains in demand in production and in the household.

Powder application for brass and copper

Practitioners often use flux that has been stored for longer than the allotted time. For borax, it is worth re-smelting. Chilled powder should be placed in a jar with an airtight lid. Neglect of this procedure can spoil the work due to the slag accumulated during storage.

At the beginning of soldering, the working area must be heated to a clearly visible red color.. Heating should start first at the edges, and then directly at the place of soldering.

Then the heated zone should be gradually sprinkled with flux, wait until it spreads in the form of a film along the edges of the part. At this point, the heated one must be dipped into the borax melt so that it is covered with a hot flux film.

As experience shows, the place of soldering is red in this case, the borax melt is colored in bluish colors. It is impossible to keep the solder in the flux for a very long time. Oxide slags may form.

Then the work area should be warmed up again. The brass will take on an orange luminous appearance. You can proceed directly to soldering. If everything is done correctly, the solder will fill all the gaps.

The soldering area will turn golden. When the process is completed, the hot zone should be sprinkled with borax powder and left to cool. Copper parts in a hot (200 ℃) state can be placed in a mixture containing equal parts acetone and water, or simply in water. It makes sense to immerse the cutters in hot sand.

A correctly made connection has a transparent film with a slight blue tint. There are no drops of solder on it. When soldering incorrectly, the seam is covered with a black porous crust.

The reason may be overheating of the working area, as a result of which slags were formed, or poor quality of the flux based on borax. This is how brass and other copper-containing alloys are soldered.

Application of solutions

For lighter metals, a solution of borax is used. It is much easier to work with liquid flux, just dip the part into it and start soldering. Jewelry, contacts, wires, and other small parts are soldered in a similar way.

Sometimes the presence of only borax in the composition of the flux is not enough. In such cases, mixtures are used for soldering. A common additive that helps to cope with the task is boric acid.

Usually acid and borax are taken in equal parts. Sometimes zinc fluorides, potassium chlorides, salts of other alkali metals are used. The powders are carefully ground with a pestle in a porcelain mortar. You can take a mortar from another material, as long as it does not absorb the mixture of borax.

With any soldering, the ends of the parts are first cleaned. This can be done with sandpaper, a stiff brush or a needle file. Then a thin layer of powder is poured.

The solution can be applied with a brush or by simply dipping the part. Then the working area is evenly heated, without reaching the melting of the parts, soldering is carried out with the required solder. It should spread well at the junction with a thin layer.

The process is easy to do at home. In production, a soldering station is convenient for permanent work. There are several types of installations with different configurations.

They are produced in our country and abroad. You can always choose a model that suits the set of functions and cost.

Copper pipe connection

Copper piping is expensive. The investment can be justified with careful installation, which is often carried out using the method using borax as a flux.

It is worth noting that today, other fluxes are also sold that are more convenient to use. One pipe is inserted into the second or fitting so that the gap does not exceed 0.4 mm.

Soldering time is short, 3 minutes. It is important that the parts remain motionless during operation. In order for the borax powder to adhere to the surface, copper is first heated with a burner.

For pipes with a diameter of up to 108 mm, the soldering process is carried out at low temperatures not exceeding 450 °. The seam is wide (up to 50 mm), but not very strong. Wide pipes, with a diameter greater than 159 mm, are soldered at high temperatures. Only professionals can perform the procedure.

In both cases, the solder melt penetrates well into the capillaries of the parts, which contributes to the formation of strong joints. The remains of borax are recommended to be removed.

It must be remembered that soldering is accompanied by the formation of smoke, so you can only work in ventilated areas.

During soldering, many types of solders are used. Each of them has its own advantages, which makes it useful for a particular area. Auger soldering flux is often used to solder difficult metals such as cast iron, steel, or copper, but can be used for other procedures as well. This is one of the most common and time-tested fluxes that are used both in the industrial sector and in the private sector. A soldering bit is relatively inexpensive and can be used for many types of soldering. It gives a complex effect, which simplifies the process and does not require the addition of other components, although more complex fluxes based on it are also found in the jewelry industry.

Copper brazing drill

A brass soldering bur helps not only to improve the properties of metal soldering, but also to clean its surface from excess films, deposits and other things that can damage a high-quality and reliable connection. In its pure form, it is a high-temperature flux, the melting point of which is approximately 700-900 degrees Celsius. But the properties of the material allow it to be easily dissolved in water, resulting in a softer flux. The degree of dissolution determines how high the melting point of the material will be. Throughout its existence, soldering specialists have come up with many ways to use and create combinations for this material. The soldering drill is made according to GOST 8429-77.

Advantages of solder drill

• Copper brazing bit is one of the few widely available fluxes for refractory metals;
• The cost of the material is relatively low compared to other materials of this kind;
• It is possible to dilute borax to the desired consistency in water, as it has good solubility;
• The flux is available in almost all stores and there are no problems finding the right brand;
• Long shelf life.

Flaws

• After application, a plaque of salts forms, which must be cleaned off mechanically;
• It is required to choose places for storage in which there is no moisture, since the flux will begin to deteriorate from high humidity;
• To prepare the material for use, you need to spend time and find the right proportion, which can lead to error.

Varieties of borax

There are two main varieties that relate to the appearance of the material. The first option is a solid form. Soldering drill flux is supplied in powder form with fine solid fractions. Due to this, it is easy to lay it on the metal surface before soldering in the right amount and it will not spread at the same time. This variety is supplied in a special box that protects the material hermetically from the penetration of moisture and other extraneous factors. Fractions are white.

The second variety, which is more often used for lighter metals and their alloys, is diluted borax. AT this case you are offered the same material, but dissolved in a liquid. As a result, it can be used at lower soldering temperatures. The use of this variety is also easier, since small parts are simply dipped into the liquid, after which they can be soldered. This is used both in the jewelry industry and in other places where work with small items is in progress. Contacts, wires and other types of equipment are in good contact with the dissolved flux. Despite the fact that the principle of how to use liquid soldering borax is somewhat different from the standard one, they have almost the same effect.

There are also varieties in the form of mixtures, when other fluxes are also used. This is necessary in cases where it is impossible to achieve the desired results with a single substance. Proportions and composition depend on specific goals. Most often it is combined with boric acid.

Composition and physico-chemical properties

Soldering borax contains sodium chloride and barium chloride, in some cases boric acid is added to it. It is not used in its pure form for all procedures, since this will require a too high melting point. Drill brazing powder is a high-temperature flux, so its main property is high temperature resistance. It should be noted that the material perfectly retains its chemical properties even at a lower concentration than supplied. Thus, the flux solution has a sufficiently high level of dissolution of oxides of all base metals, for which it is used.

It can also dissolve fatty films and other unnecessary things that will interfere with the normal solderability of the material. Brown soldering protects against many types of marriage that can occur in work.

Specifications

There are two main grades of the substance, which are defined according to GOST as grade A and grade B:

• A - used for non-ferrous metals, frits, faience dishes, etc.;
• B - for enamels, glazes, technical equipment, plumbing, wire, etc.

Soldering Features

The minimum soldering temperature, even when working with a solution, must be more than 400 degrees Celsius. Most often, mixtures are used in place with boronic acid, due to which the composition acquires versatility and a lower operating temperature.

During combustion, the drill becomes like a kind of glass mass.

During the period of direct soldering, salts are formed at the place of application of this material. They give a sediment visible to the eye, which is not desirable to leave on the surface. To get rid of it, you should use a mechanical cleaning method.

When mixing borax with any other substance, proportions of 1 to 1 are most often used. If solid components are mixed, it is best to grind them in a mortar made of porcelain or other material that does not have absorption properties.

The solution liquid is preheated. If the solution is evaporated, then in the end there will be a solid residue from the flux, since its boiling point is above 100 degrees Celsius. It is worth noting that it almost never contains borax. Most often, it includes.

To make borax more active, fluoride or chloride salt is added to it. There are two ways to apply flux to solder a drill. This may be the placement of a solid powder at the place of soldering, as it will heat up and melt when exposed to temperature. You can also use everything in a liquid form of a solution, simply by immersing the workpieces in the flux, and then use ordinary soldering.

Popular firms and brands

The following common manufacturers of this flux are found on the modern market:

• Buisky chemical plant;
• Chempack;
• Xiamen.

Card game, a river in the Novosibirsk region, 3 villages, an ancient city and a small people of Nigeria. All this is a storm. However, the word has another meaning. This is what the mineral is called.

Its chemical formula is borate. The brown stone became due to color. white. The name of the crystals is translated in the same way. The concept is taken from the Persian language. What does it mean for humanity, further.

What is borax

Bura is a substance that is soluble in water. It takes 14 parts of it to 1 part of sodium borate. In this form, the mineral can be found in nature. It is dissolved in water bodies, and is also found in bottom sediments. These abound in the salt lakes of India and Tibet. In Asian countries, the stone is called not brown, but tincalom.

The substance melts already at 60 degrees. If you bring the temperature to 320 degrees Celsius, the moisture contained in evaporates. It turns out an anhydrous powder. For its melting, already 741 degrees are needed.

Borax crystals are almost transparent or greyish, but always have a characteristic oily appearance. The stone looks like it has been oiled. It doesn't taste greasy, but sweet. Geologists can lick a mineral a little to make sure it's identified correctly.

Production and use of borax

In the Middle Ages, borax was received in. Raw materials were mined in those very lakes of India, but they were purified on the lands of Italy. Crystals were brought here from the eastern country in bags of skins.

In Venice, the mineral was crystallized from an aqueous solution, freeing it from impurities. In this way, the substance is obtained even now, but already on a global scale.

The scale of production of borax is wide due to the same scope of the substance. It can be found in pharmacies. Doctors have long recognized sodium borate as an antiseptic. The main release form borax in glycerin. It is, in particular, prescribed for fungal skin diseases.

There is also borax jewelry. It is used as a composition for soldering. When fastening metal parts, it is necessary to clean their surface, otherwise the connection will not be strong. Surface treatment is carried out just brown. It is ideal when working with , and .

In the production of glass, it is also necessary bura. Buy the product is sought both as a flux and as a binder component of fiberglass. Without the admixture of sodium borate, the final product is brittle and of poor quality. Borax at times increases the resistance to mechanical and chemical influences.

E-285 is a food preservative. The same drill is hidden under the digital code. In Russia and European countries, the use of additives is prohibited. The toxicity of the substance is minimal, but sodium borate is not excreted from the body.

The preservative accumulates, and the toxic effect on the body increases. Previously, E-285 was used everywhere to preserve margarines, oils, caviar. The additive is allowed now, but only in third world countries.

Borax is included in the mixture. This is the initial mixture of components for the production of glazes. Therefore, the substance is contained in the coatings of dishes, ceramic tiles. In household chemicals, there are also bura. Price detergents includes the cost of a water softener, in the role of which sodium borate acts.

In its pure form, the mineral is used on the farm for cleaning plumbing. It is brought to a shine with a ground mineral. Furs are also sprinkled on them so that they are not eaten by moths. And the powder helps with fleas.

In the textile industry, brown is used to pickle fabrics. The concept is not connected with poisoning, it means only surface treatment before painting.

Borate allows dyes to be distributed evenly and securely fixed in the fibers of fabrics. If the matter sheds heavily during washing, it is likely that it was not pickled with borax.

Of course, the substance is also used in the production of boric acid. But, there is also a reverse cycle, when borax is obtained from boric acid and. This process was first carried out by Enouville, a French chemist. The experiment was carried out in 1748.

Is borax harmful to human health

As already mentioned in the example of a dietary supplement, sodium borate is toxic. But, the harmful effect is so minimal that in small doses it does not have a negative effect.

As Hippocrates said: “everything is medicine, and everything is poison.” Only doses matter. So, in medicine, even for pregnant women is allowed bura.