How to use soldering borax, how to solder iron, composition, what is it and what is it for?

Borax is a high-temperature flux produced in powder form and used when joining metal parts by soldering. Borax soldering flux melts at a temperature of 700 degrees Celsius, which is why it is called high-temperature flux.

Borax has its own GOST that regulates its composition and production. According to this GOST, borax should dissolve in water and, when solidified, turn into a transparent mass. In this article, we will tell you everything about borax powder.

Advantages of soldering borax

Copper borax is one of the few widely available fluxes for refractory metals;
The cost of the material is relatively low in comparison with other materials of this kind;
It is possible to dilute borax to the desired consistency in water, since it has good solubility;
Flux is available in almost all stores and there are no problems finding a suitable brand;
Long shelf life.

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Description and external signs

Borax mineral is an aqueous sodium borate with hydroxyl. It is also popularly known as boric salt. In Asian countries it is called tincal. This substance resembles almost colorless crystals. Origin of the name: from the Arabic word bauraq - translated as “white”. The form of release of borax in pharmacies and hardware stores is a white fine-crystalline powder.

Chemical composition

The components of borax are the sodium salt of boric acid and a strong base (water, sodium). Chemical formula: Na2(B4O5)(OH)4 8H2O

The practical significance of borax is to serve for the extraction of boron.

Molecular weight of the substance: 381.37; Density: 1.7; Specific gravity: 1.69 – 1.8; Maximum birefringence: δ=0.025; IMA classes: borates.

What is it and what is it for?

Soldering borax is a high-temperature type of powdered flux that is used when joining metal products by soldering. Melting of this substance can occur under the influence of temperatures exceeding 700 degrees Celsius. Soldering borax has its own GOST, according to which it is manufactured and its characteristics are regulated.

The substance in powder form looks very similar to salt, in other words it is called sodium tetraborate. The synthesis of borax occurs naturally, and its extraction is carried out from salt lake deposits.

The use of this substance is quite wide, but most often it is used for soldering copper pipes.

The advantages of using borax include the following:

the materials that are planned to be processed may have different temperature conditions;
obtaining a high-quality, reliable weld not only between metals, but also between metal and non-metal surfaces;
ease of soldering seams if necessary to separate parts;
when soldering, the parts do not warp or deform;
increased productivity during capillary soldering;
obtaining smooth and durable seams even from a craftsman with little experience.

The disadvantages of sodium tetraborate are as follows:

release of a large volume of salts, which harden on the metal at high speed;
absorption of moisture from the environment;
the difficulty of selecting the right amount of borax for an inexperienced welder.

Welding of copper and copper alloys

When welding copper and its alloys, it is necessary to take into account some properties of copper (high thermal and electrical conductivity, the ability to absorb oxygen and hydrogen) and the components included in its alloys (zinc, tin).

For copper, the following types of welding are mainly used: gas, electric arc with carbon electrode and metal with coatings, in shielding gases and submerged arcs.

When gas welding copper

filler rods made of pure electrolytic copper or copper containing up to 0.2% P and up to 0.3% Si are used.

Usage

Before connecting parts, you need to pay attention to their preparation. The latter is in the following sequence:

Clean the joints of the elements from dirt and corrosive damage using a scraper with coarse bristles. The flux itself will deal with the oxide film on the surface.
Use a blowtorch flame to heat the joints of the structures to be welded.
During heating, leave a gap of at least 1 mm between the elements.
Introduce borax with solder into the gap, also heated by a lamp, while continuing heating.
When borax crystallizes, turn off the blowtorch.
After the parts have cooled, remove salt deposits with a brush.

The first soldering with borax may not be successful due to the small amount of the substance. It is recommended to select it practically. To improve the seam, you can use boron flux with the addition of fluoride or chloride elements.

Drill for soldering brass, copper or aluminum and flux: what are they for and how to use

Borax is a powder that is added to so-called high-temperature flux mixtures for soldering metal products. The melting point of borax is quite high – 700 – 900°C.

Soldering borax is very convenient in technical use, all its properties are well known, convenient and described in a special regulatory document - GOST 8429-77.

Where and how is borax used?

From a chemical point of view, borax is a sodium salt with the complex name “sodium tetraborate decahydrate”. With its participation as an active element in the protective flux mixture, a wide variety of metals are combined, up to complex and capricious alloys, for example, copper.

Tools and consumables for soldering.

At a high temperature, the borax begins to melt, as a result of which the surfaces to be welded are cleaned with the simultaneous dissolution of oxides in the hot flux mixture.

The essence of this process is the formation of salts followed by surface crystallization. This crystalline deposit is easily removed after the welding process.

How is flux with borax prepared?

The boron flux mixture for use in working with metals has its own characteristics and is prepared as follows: for example, borax for soldering brass is mixed with boric acid in equal proportions.

The mixture should be thoroughly ground in a special chemical vessel, and then all the liquid should be evaporated to form a final dry residue. Then fluorine and chlorine salts are added to the resulting substance. As a result, an active flux is formed, which will be an excellent assistant in heating metal parts of various types.

Advantages of using borax in working with metals

These advantages are especially evident in the processes of soldering brown copper pipes, which are often important components of modern pipelines. Such technologies are now in great fashion.

They are used both for connecting new pipes and for high-quality repairs of old pipelines that have been in use for a long time.

The most important role of borax in the flux composition is to remove the oxide film from the metal surface and activate the spreading of liquid solder over the surface of parts.

Technical requirements for fluxes.

Here are its technical advantages:

Metal parts in any, even the most “inconvenient” combination can be merged.
The connections are strong and reliable even between metals and non-metallic materials.
Work can begin with metals having any initial temperature.
Using this technology, parts can not only be connected, but also effectively separated - they can be unsoldered without any problems.
The difference between soldering and classical welding is that the base metal does not melt, and therefore there is no phenomenon called “warping”. As a result, the parts are not deformed in any way.
Borax helps in effective adhesion of solder to metal surfaces.
Technical drill is indispensable for the method called “capillary soldering”: it affects its performance.
Soldered joints are characterized by high quality and durability.

Stages of soldering with borax

The whole process consists of successive steps, the implementation of which is mandatory:

Careful preparation of workpiece surfaces before heating.
Cleaning is carried out to get rid of oxide films, this is where technical drill is needed.
A blowtorch heats the surfaces to be welded to the desired temperature.
Heated metal solder in a liquid state is introduced into the space between the parts.
The essence of the connection is the combination of the base metal with liquid metal solder in a well-heated state.
The process ends with the final crystallization of the solder.

Soldering copper pipes using borax

First you need to stock up on the necessary tools and materials:

blowtorch or gas torch;
special solder, selected taking into account the nature of the metals that need to be soldered;
borax with optimal properties according to GOST 8429-77;
metal brushes for cleaning parts;
metal cutting tool;
brushes for coating parts with a flux layer.

The choice of gas burner deserves a special warning. The fact is that these devices are offered on the market in huge quantities and in different models.

A fashionable device in gas burners is an automatic piezo ignition system.

And now the main stages of the soldering process using borax to connect two copper pipes:

Thorough cleaning of the surfaces inside the pipes with special brushes with metal bristles.
Now clean the outer surfaces of the pipes using sandpaper.
Applying technical borax using a brush.
Joining pipes that are coated with a flux layer to each other.
Heating the parts with a gas burner. The flame action must last for at least 20 seconds.
Solder is introduced onto the working area, which is also melted under the action of the burner. Solder is applied as evenly as possible.

Quality control of connections using borax flux is carried out using different methods: destructive and non-destructive. Most often, an external examination is sufficient to determine possible defects. You can even do this with a magnifying glass.

Application of brass and copper powder

Practitioners often use flux that has been stored longer than expected. To solder with brass, the borax must be re-melted. The cooled powder should be placed in a jar with an airtight lid. Neglecting this procedure can ruin the work due to waste accumulated during storage.

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

Then the heated area 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 brass solder must be dipped into the molten borax so that it is covered with a hot flux film.

As experience shows, the soldering area is red in color, while the borax melt is colored bluish. You cannot keep solder in the flux for a very long time. Oxide residues may form.

Then you should warm up the work area again. The brass will take on an orange glowing appearance. You can proceed directly to soldering. If 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 solder drops on it. If soldering is performed incorrectly, the seam becomes covered with a black porous crust.

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

How is the soldering process performed?

When performing soldering at home, you need to understand one subtlety. When borax has been stored in powder for a long time, it is better to melt it first, for which a crucible or fireclay is used. The resulting substance should be crushed into a powder and placed for storage in an airtight container.

Tightness is a prerequisite: the powder is hygroscopic, and due to the presence of moisture in the flux, slags with metal can form.

Before applying flux, the soldering area is heated red-hot. It is better to heat not the soldering area itself, but next to it, gradually transferring the heat to the junction of the elements. When the parts have warmed up, the joint should be sprinkled with a small amount of borax. At the same time, monitor the temperature, wait until the borax melts well and spreads over the soldering area in the form of a film.

It is better to solder with brass, the rod is dipped in borax, after which you need to wait for the powder to melt. The flame that the soldering torch emits should be close to the soldering area, but you don’t need to hold it like that for long. This way you can get a connection with slag and a layer of scale, which will be difficult to remove. Immediately before the solder is applied, the soldering area should be red and the melted borax should be bluish. This moment can be considered optimal for adding solder.

Next, a solder bar coated with borax powder must be brought to the soldering site and heated to the temperature at which the solder begins to melt (in the case of brass, until it glows orange). The melting point of brass and borax is almost the same. Next, the actual work process begins.

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Composition and properties

The chemical nomenclature of soldering borax indicates that it is a crystalline hydrate of the sodium salt of tetraboric acid . If the substance contains 10 water molecules, then it is called sodium tetraborate decahydrate. In simple words, it is a salt that is surrounded by a shell containing 10 or 5 water molecules .

A temperature of 64 degrees causes decahydrates to melt and lose water in the process. Borax is dehydrated at a temperature of 380 degrees Celsius. Tetraborate is characterized by withstand heating up to a temperature of 742 degrees and melting when it increases.

Borax contains sodium chlorine, barium chlorine and, in some cases, boric acid. Flux in the form of a solution has a high ability to dissolve metal oxides, as well as fatty films and anything unnecessary that can prevent the adhesion of materials.

Thanks to the use of borax during soldering, many products are produced without defects.

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Technical drill

Technical borax Na2B4O7 - 10H2O loses water during melting and dissociates to form atomic boron. The resulting atomic boron diffuses into the surface of the part. Optimal boriding mode: current density at the cathode 15 - 0 20 A / cm2, voltage 2 - 14 V, temperature 930 - 950 C, holding time 2 - 4 hours; this results in a diffusion layer with a thickness of 0 15 - 0 35 mm. [1]

Technical borax is produced in two grades. [2]

Technical borax is recrystallized from hot water (temperature about 60 C), the crystals of borax decahydrate that fall out during cooling are filtered on a Buchner funnel and dried between sheets of filter paper. During long-term storage, borax crystals may lose part of the water of crystallization, so they must be stored in a jar with a ground-in stopper or in a desiccator, at the bottom of which a porcelain cup with a saturated solution of sodium bromide containing an undissolved excess of this salt is placed.

Kinds

Based on appearance, welding drills are divided into 2 types.

Solid . In powder form, flux has the form of solid fine fractions. This shape makes it easy to lay borax on a metal surface before the soldering process, while the substance does not spread. Solid borax is sold in boxes that are sealed, thereby protecting the substance from moisture and the negative influence of the environment. In the powder fraction, borax is white.
Divorced. This type of borax is considered the most suitable for light metal and its alloy. The substance is the same powdered borax, but dissolved in a liquid. This feature of the flux makes it possible to use it at low soldering temperatures. Using diluted borax is quite simple: small metal elements are dipped into it and then soldered. This flux is popular in jewelry, as well as when working with wires and contacts.

Flaws

After use, a deposit of salts forms, which must be removed mechanically;
It is necessary to choose storage areas that are free of moisture, since high humidity will cause the flux to deteriorate;
To prepare the material for use, you need to spend time and choose the right proportion, which can lead to errors.

Varieties of Borax

There are two main varieties that relate to the appearance of the material. The first option is the solid form. Borax soldering flux is supplied in the form of a powder with fine solid fractions. Thanks to this, it is easy to lay it on the metal surface before soldering in the required quantity 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 foreign factors. Fractions are white.

The second type, which is more often used for lighter metals and their alloys, is diluted borax. In this case, you are offered the same material, but dissolved in liquid. Due to this, it can be used at lower soldering temperatures. Using this type 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 small items are worked. Contacts, wires and other types of equipment come into good contact with dissolved flux. Despite the fact that the principle of using borax for soldering in liquid form 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 using one substance. Proportions and composition depend on specific goals. Most often it is combined with boric acid.

Composition and physicochemical properties

The composition of borax for soldering includes 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 would require too high a melting point. Drill soldering powder is a high-temperature flux, so its main property is resistance to high temperatures. It is worth noting that the material perfectly retains its chemical properties even at a lower concentration than what is supplied. Thus, the flux solution has a fairly high level of dissolution of the 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 soldering of the material. Brown soldering protects against many types of defects that can occur in work.

Popular manufacturers

Soldering borax is sold under two brands:

A – used when working with non-ferrous metals, frit, earthenware and others;
B – indispensable for enamel, glaze, technical equipment, wire and plumbing elements.

Popular manufacturers of this substance today include Rexant, ZUBR, Latus and others . These products are in good demand among consumers, as they have high quality characteristics and an affordable price.

Buisky Chemical Plant, KhimPek and Xiamen have also proven themselves well.

List of required components

There are several options for preparing sodium tetraborate yourself. For the simple method you will need:

baking soda;
boric acid;
plastic container;
wooden stick;
napkin.

The second method involves longer production times. It will require:

construction borax (this is what a solution of boric acid is called in a pharmacy);
glycerol;
plastic container.

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Megamaster.info will tell you below how to make sodium tetraborate yourself at home using these components.

Advantages and disadvantages

The advantages of drill flux include:

availability and low price compared to similar materials;
no deformation of parts, since the base metal does not melt;
connection of metal with non-metal;
the ability to solder parts with different initial temperatures;
ease of desoldering during dismantling;
increasing the productivity of capillary soldering;
high quality seams, made even by a beginner;
long shelf life of flux.

Disadvantages include :

the need to mechanically clean the surface from salts that are released when the borax is heated and, after cooling, settle on the metal;
high hygroscopicity, so the flux becomes damp even in a tightly closed container;
the difficulty of determining the optimal proportion for beginners.

Scope of application of the drill

Sodium tetraborate has been actively used for the following purposes:

as a flux during soldering and melting of metals;
in analytical chemistry studies as a standard substance for determining the level of acid in a solution. Borax is also used to establish the characteristics of metal oxides;
widespread use in the creation of glazes, enamel, glasses for optical instruments and decoration;
the powder is used in pharmaceuticals and paper production;
is a natural preservative and means for disinfection and control of parasites;
is a component in the chemical industry to create household cleaning products;
relevant application in the creation of cosmetic products;
borax is used as a base for creating boron;
the substance is a component for creating insulating building materials;
in light industry, sodium tetraborate is applied to the product before the painting procedure.

Using a drill in everyday life

Borax can be found in most grocery stores. It is a relatively inexpensive product, making it an excellent choice for many household projects.

Use of sodium tetraborate as a medicine

The substance is very effective in controlling pests: cockroaches, ants and other household insects. The mixture is ready by mixing equal parts of powder with sugar. Sugar helps attract beetles and borax exerts its detrimental effect on the insect. It is recommended to keep the substance in hard-to-reach places, away from pets and children. Optimal places: under stoves, refrigerator and sink. Borax also works well against mice. You just have to apply the powder in the areas where the mice are located, and the borax will rid you of the pests. You can also sprinkle the solution on the carpet and vacuum it to eliminate the presence of fleas or treat the mattress to get rid of bedbugs.

Borax will get rid of rust. Mixing 1 cup of powder with 2 cups of water and 1 tablespoon of lemon juice makes an effective anti-corrosion agent. The paste-like solution is applied to the rusty items for about 15 minutes. After which the rust can be easily removed by mechanical friction.

Sodium tetraborate is a universal cleaner. Two tablespoons of borax are mixed with 2 cups of water to create an all-purpose cleaner. The solution can be applied in a spray bottle and used to clean kitchen surfaces and bathroom tiles and ceramics. Borax is great for removing very stubborn stains. Borax will help remove stubborn stains from the floor.

Borax will allow you to flush your home plumbing fixtures. Simply place ½ cup of borax into the drain with a few cups of warm water. Borax breaks down dirt that gets stuck in pipes. This will not only remove excess and unclog the drain, but also disinfect the system.

Application in forging and forge welding

Borax is actively used as a flux for forging and forge welding. The powder is a source of boron oxide, with excellent antioxidant properties. Borax can, if necessary, remove small cracks during metal processing, change the shape of a product, or when heated during artistic forging and blacksmithing of metal. The substance is classified as a high temperature flux. The processed workpiece with borax is characterized by more wear-resistant characteristics and durability.

Using borax in soldering

During the melting of borax at a temperature of 700-900 °C, the surface of the material being processed is cleaned, and all excess inclusions are dissolved in the flux. During the processing of a material by forging, a thick layer of scale is gradually created. In some cases, the metal being processed may completely burn due to overheating of the part. But by using a thin layer of borax, this scenario can be avoided.

Where and how is borax used?

According to this technology, additional metal solders are used for joining; they can also be of different compositions.

Tools and consumables for soldering.

At a high temperature, the borax begins to melt, as a result of which the surfaces to be welded are cleaned with the simultaneous dissolution of oxides in the hot flux mixture.

The essence of this process is the formation of salts followed by surface crystallization. This crystalline deposit is easily removed after the welding process.

Use of boric acid and borax in soldering

Boric acid, borax and their mixtures can be used in soldering in cases where copper, iron and zinc have to be dealt with. They are usually used successfully for soldering low-carbon steel and iron (galvanized or non-galvanized) with copper, copper-zinc and silver solders that do not contain manganese and nickel, as well as copper, bronzes (especially ferrous), tombac and brasses with a high melting point - copper-zinc and silver solders (without manganese and nickel).

Crystalline borax (Na2B4O7*10H2O) begins to melt at a temperature of 75 degrees; as heating increases, it loses water and gradually turns into anhydrous salt (Na2B4O7), melting at 783 degrees. Boric acid (H3BО3) melts at 570g. But its active temperature is much higher than that of borax. Therefore, when soldering above 1050g. Boric acid is used, and at lower temperatures (below 800 degrees) - borax.

Since boric acid becomes liquid at a higher temperature, adding it to borax makes the flux thick and viscous, requiring an increase in the operating temperature of soldering.

When soldering alloys containing acidic oxides (for example, silica when soldering cast iron), oxides or sodium salts in the form of sodium hydroxide (NaOH) or sodium carbonate (Na2CO3) can be added to the fluxes.

Varieties

According to its appearance, borax is divided into 2 types:

Solid in the form of a fine-grained white powder. Sold in sealed packaging to protect against moisture. It is convenient to apply the powder in the required quantity to the surfaces to be joined, since the flux does not spread.
Diluted. This is borax dissolved in liquid, which can be used for soldering non-ferrous metals at low temperatures. Small parts are simply dipped into the solution, which is convenient when working with jewelry, wires, and electrical appliance terminals. In terms of efficiency, diluted flux is almost equal to solid flux.

Depending on the quality, the brand is designated by the letter:

A - consists of 99.5% decahydrate and 0.5% impurities. Used for frit, earthenware, etc.
B - impurity content up to 6%. Used for working with glaze, enamel, and plumbing equipment.

Composition of borax

For soldering, it is better to use grade B, as it meets all requirements. And the price is less.

The shelf life of both brands is no more than 6 months.

Soldering brass - a reliable connection at home

A weighed portion of technical borax 0 4596 g, titrated with a solution of HC1 with R0 1062, 21 20 ml was consumed. [4]

Industrial drill supplied by industry contains hygroscopic and crystallization moisture, which, when entering the weld pool, sharply increases the gas porosity of the weld metal. In addition, part of the borax, when moisture evaporates from it, foams and is blown out by the flame, as a result of which areas of the metal are exposed and oxidized. [5]

Borax is obtained from common technical borax (Na2B4O7 - 10H2O) after calcination in an oven at a temperature of 700 - 800 C on a stainless steel baking sheet or in an open fireclay crucible filled with ciu in height at V, due to the strong swelling of borax when heated. After calcination, the borax is ground in a mortar or ball mill. This borax should be stored in a hermetically sealed jar. [6]

For the production of 1 ton of technical borax containing 99 0 - 99 8% Na2B4O7 - 10H2O, 0 9 - 1 t of boron-calcite (40 - 42% B2O3), 0 14 - 0 18 g of soda, 0 10 - 0 15 t of bicarbonate are consumed and 0 01 g of bleach. [8]

To obtain calcined borax, technical borax is poured into an open porcelain or fireclay crucible at 1/10 of its height and placed in an oven at 700 - 750 C. After swelling and settling, the borax is ground into powder in a ball mill or mortar and stored in vessels with an airtight lid before use. [9]

Experimental work carried out at TatNIPIneft showed the possibility of using technical drill as an indicator element for identifying oil-bearing reservoirs flooded with injected fresh or formation water based on different rates of dissolution of the penetration zone. [10]

The temporary compressive strength of gypsum NBSS samples with the addition of 2 25 and 2 50% technical borax is given below. [eleven]

To sustainably maintain the pH value of the drilling fluid, starting from a depth of 5600 m until the end of drilling, it was decided to use technical borax, and soda ash to precipitate calcium and magnesium ions. [12]

Sulfonol, Progress, ANP-2 and a mixture of surfactants (OP-7 sulfonol), reagents (CMC and KSSB), as well as technical borax were tested as retarders for the gypsum solution. However, only with the introduction of borax was the required strength of the gypsum stone obtained. [14]

They produce technical and food grade borax. Technical borax is obtained by reacting boric acid and soda in a boiling solution. After separating the sludge on a filter, borax crystallizes from the cooled solution, which is separated in a centrifuge and washed. Food grade borax is obtained by recrystallizing industrial borax. [15]

Peculiarities

How to use borax in your work to get the highest quality results? To answer this question, we will talk about all the stages of soldering using borax. First of all, you need to prepare the metal. Clean it from dirt and corrosion. Pay special attention to stubborn stains; they must be removed with a rough brush. The oxide film does not need to be removed, since the borax will handle it itself.

Then, using a blowtorch, you need to heat the surface of the parts to be welded. Leave a small gap between the pieces. Add borax and solder into it, preheated with a blowtorch. Once the borax begins to crystallize, you can stop heating. When borax hardens, it becomes transparent and forms a lot of salts. Remove them from the metal surface. It is important to follow the sequence of operations and not to overdo it with the amount of flux. It's hard to say how much borax to use because it depends on the metal and the weld you want to create. Experiment and with experience you will begin to understand which dosage is preferable. Borax can be used in powder form, or you can make boron flux from it. Boric flux is widely used for soldering copper pipes and cast iron parts. Mix boric acid and borax in a one to one ratio. Then you need to crush the resulting mass in a bowl, and then evaporate it, getting rid of excess liquid. Fluoride and chloride salts are added to the dry residue. Boric flux is ready! It has active properties, allowing you to solder copper parts faster and with better quality.

What is borax

In this case, the reaction follows the following equation:

the fusible salt (Na2O)2SiO2 turns into slag.

Borax, boric acid and their mixtures have been used as soldering fluxes since ancient times. One of the advantages of boron compounds is their lack of corrosive effect on the seam. Despite this, flux residues after soldering must be removed, since the glassy mass of flux formed during soldering makes it difficult to control solder joints, especially for density.

In addition, during prolonged use, flux residues crumble and turn into a porous substance that can absorb moisture, which can cause corrosion of the product.

To remove residues of borax, boric acid or their mixture, the product should be washed with water or subjected to mechanical treatment.

Both require quite a long time; to speed up cleaning from flux, sometimes the hot product after soldering is immersed in water. The effectiveness of this method is explained by the large difference in the coefficient of thermal expansion of the metal and the flux, as a result of which, upon sudden cooling, the latter cracks and is easily removed with a steel brush. However, such cooling after soldering is not acceptable.

If, when soldering with brown and boric acid, the seam is not always cleaned of fluxes, then removal of residues containing NaOH and Na2CO3 is a mandatory operation, since these compounds cause intense corrosion of the product. This requires long and thorough rinsing of the product with water.

Areas of application

Borax, which is a salt containing a weak boric acid and a strong base, also has a scientific name - sodium tetraborate decahydrate. Using this substance, used as a flux, soldering of metals such as steel, cast iron, copper and its alloys is performed. In this case, for such soldering, medium-melting solders are used, the basis of which can be copper, brass, silver and gold.

When borax melts, which occurs at a sufficiently high temperature, the surfaces of the parts to be joined are cleaned, and the oxides that are present on them dissolve in the heated flux. During the soldering process, for which a refractory flux such as borax is used, which meets the requirements of GOST 8429-77, salts are formed that crystallize on the surface of the joint being formed. After completion of the technological operation, salt deposits must be removed.

GOST requirements for the composition of borax-based flux

To obtain boron flux from borax, which can be used when soldering parts made of copper, cast iron, steel and other metals, this substance must be mixed with boric acid in a 1:1 ratio. The resulting mixture is thoroughly ground in a porcelain container, and then the excess liquid is evaporated to obtain a dry residue, to which fluoride and chloride salts are added. Using this technology, active fluxes are obtained that allow high-quality soldering of parts made of various metals.

You can familiarize yourself with the GOST requirements for technical borax (sodium tetraborate) by downloading the document in pdf format from the link below.

GOST 8429-77 Borax. Specifications Download

How to use borax when soldering materials together

Soldering where hard solders will be used means that materials with a melting point of more than 400°C will be used. Light solders have temperatures below this value. Brazing usually involves using a mixture of boric acid and borax.

The composition of borax is such that it easily dissolves in water. When burned, it takes the form of a glass mass; its melting point can fluctuate within the following limits: 700-900°C. When soldering with borax, salts are formed that will need to be removed, for which mechanical cleaning is used.

Table of composition and use of borax.

Borax is a high-temperature flux that is used to join cast iron and steel, and copper alloys. In this case, medium-melting solders are more often used: copper, brass, gold and silver. By melting borax, you can dissolve metal oxides and clean the surface of the elements being joined. When completing soldering, remove any remaining salt.

Borax mixed with boric acid 1:1 produces boric flux. The components must be well mixed, then they must be ground in a porcelain mortar.

The solvent is heated in distilled water, then evaporated to obtain a solid residue. For greater flux activity, chloride or fluoride salt can be added to the mixture. You can consider an example with the connection of copper elements.

Advantages of using borax in working with metals

These advantages are especially evident in the processes of soldering brown copper pipes, which are often important components of modern pipelines. Such technologies are now in great fashion.

They are used both for connecting new pipes and for high-quality repairs of old pipelines that have been in use for a long time.

The most important role of borax in the flux composition is to remove the oxide film from the metal surface and activate the spreading of liquid solder over the surface of parts.

Technical requirements for fluxes.

Here are its technical advantages:

Metal parts in any, even the most “inconvenient” combination can be merged.
The connections are strong and reliable even between metals and non-metallic materials.
Work can begin with metals having any initial temperature.
Using this technology, parts can not only be connected, but also effectively separated - they can be unsoldered without any problems.
The difference between soldering and classical welding is that the base metal does not melt, and therefore there is no phenomenon called “warping”. As a result, the parts are not deformed in any way.
Borax helps in effective adhesion of solder to metal surfaces.
Technical drill is indispensable for the method called “capillary soldering”: it affects its performance.
Soldered joints are characterized by high quality and durability.

Borax in the household 02/17/2017 10:45

Borax in the household

There are so many chemicals that are not in stores now – it’s just mind-boggling! Meanwhile, very often all this diversity consists of 3-4 drugs in a variety of packages and combinations. In reality, all this endless variety of prices and packaging differs in how promoted the brand is, and in the useless flavors and dyes.

Borax or Borax is one of the remedies that has recently been used very widely. Its chemical name is sodium tetraborate, chemical formula is Na2B4O7. This chemical compound is considered toxic, but is used in the food industry as a preservative E285. True, in Russia and the USA the use of this food additive is not recommended, although it is no more poisonous than table salt. However, we are interested in this chemical preparation not as a product, but as a universal remedy for a wide variety of household uses.

So, the uses of borax

1. Cleaning the oven. Requires 8 tbsp. spoons of baking soda, half a glass of salt and 4 tbsp. spoons of borax. All this should be dissolved in warm water. The resulting solution or paste, depending on the amount of water, can perfectly clean the oven walls. After cleaning, rinse the oven with warm water.

2. Universal cleaner for smooth surfaces. Dissolve in 2 cups of warm water for 2 hours.

spoons of borax, 2 tbsp. spoons of 10% vinegar and 3 drops of tea tree oil. Use the resulting mixture with a sprayer. This product also works great as a dishwasher cleaner.

3. Window cleaning liquid. Dissolve 2 teaspoons of borax in 3 glasses of water. Spray the glass with the solution and wash it with regular newsprint or a microfiber cloth.

4. Solution for washing organic contaminants. Dissolve in 300 ml of water for 1 hour.

Stages of soldering with borax

The whole process consists of successive steps, the implementation of which is mandatory:

Careful preparation of workpiece surfaces before heating.
Cleaning is carried out to get rid of oxide films, this is where technical drill is needed.
A blowtorch heats the surfaces to be welded to the desired temperature.
Heated metal solder in a liquid state is introduced into the space between the parts.
The essence of the connection is the combination of the base metal with liquid metal solder in a well-heated state.
The process ends with the final crystallization of the solder.

How to solder metal using borax

Soldering of metals 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 molten solder. For soldering copper products, borax solder ideally meets all requirements. The substance has been known since the Middle Ages. It was mined in the lakes of India and Tibet, then transported to Europe, where it was used for processing fabrics and leather, and producing glass.

Borax is widely used for working with metals. When manufacturing or repairing metal products, borax soldering is carried out. First of all, the method is used for parts made of copper and brass. A special type of this flux is used when repairing jewelry.

Composition and properties

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

If the composition contains 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 water dipoles.

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

This gradual melting of borax is somewhat confusing to ordinary consumers who are accustomed to the fact that the substance melts strictly at one temperature value. 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 standardized by the state standard. There are two grades of raw materials that represent technical borax:

Grade A is 99.5% salt decahydrate. The remaining 0.5% consists of carbonates, sulfates, and tiny amounts of lead and arsenic compounds;
grade B - 94% decahydrate, the impurity content of 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 grade B borax as a flux. It fully meets the soldering requirements and is cheaper than grade A raw materials.

Advantages and disadvantages

Borax-based flux is very popular. This material is always on sale. For soldering copper products, borax is the most affordable flux with budget prices.

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

Depending on the elemental composition of the parts, you can use not only crystalline powder, but also a solution. Crystalline hydrate is highly soluble in water.

There are some difficulties when using borax. The solder area is covered with plaque after soldering is completed. It needs to 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 home.

Application of brass and copper powder

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

As experience shows, the soldering area is red in color, while the borax melt is colored bluish. You cannot keep solder in the flux for a very long time. Oxide residues may form.

Then you should warm up the work area again. The brass will take on an orange glowing appearance. You can proceed directly to soldering. If done correctly, the solder will fill all the gaps.

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

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

Application of solutions

For lighter metals, a borax solution is used. Working with liquid flux is much easier; you just need to 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 borax alone in the flux is not enough. In such cases, mixtures are used for soldering. A common additive that helps cope with the problem is boric acid.

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

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

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

The process can be easily done at home. In production, a soldering station is convenient for constant 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 pipelines are expensive. The investment can be justified with careful installation, which is often carried out by capillary soldering using borax as a flux.

It is worth noting that today, other fluxes are 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 stationary during operation. In order for the borax powder to stick to the surface, the copper is first heated with a torch.

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 connections. It is recommended to remove any remaining borax.

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

Soldering copper pipes using borax

Borax application table.

First you need to stock up on the necessary tools and materials:

blowtorch or gas torch;
special solder, selected taking into account the nature of the metals that need to be soldered;
borax with optimal properties according to GOST 8429-77;
metal brushes for cleaning parts;
metal cutting tool;
brushes for coating parts with a flux layer.

The choice of gas burner deserves a special warning. The fact is that these devices are offered on the market in huge quantities and in different models.

A fashionable device in gas burners is an automatic piezo ignition system.

Our advice: you can choose a burner with it only if you are completely sure that the product was manufactured by a well-known and reputable company. If you are not so sure, it is better to buy a high-quality classic model.

And now the main stages of the soldering process using borax to connect two copper pipes:

Thorough cleaning of the surfaces inside the pipes with special brushes with metal bristles.
Now clean the outer surfaces of the pipes using sandpaper.
Applying technical borax using a brush.
Joining pipes that are coated with a flux layer to each other.
Heating the parts with a gas burner. The flame action must last for at least 20 seconds.
Solder is introduced onto the working area, which is also melted under the action of the burner. Solder is applied as evenly as possible.

Soldering flux

The last two elements vigorously deoxidize the weld pool.

The most common flux for welding copper contains 70% borax, 10% boric acid and 20% table salt.

The power of the burners when welding copper, due to its high thermal conductivity, should be 1.5-2 times greater than when welding steel.

Copper welding is carried out at an increased speed (to avoid overheating of the metal near the welding site) with the torch mouthpiece tilted at an angle of 70-80° to the surface of the product. Products made of copper of large thickness are heated during welding of the second torch. It is recommended to forge a copper weld at 400–500 °C in order to increase its mechanical properties, and anneal the product to obtain a fine-grained structure. The welding flame should be normal.

When welding copper with a carbon electrode

You can use an open or closed (submerged arc) arc.
When welding with an open arc, filler rods made of phosphorous copper are used with a coating applied to them, which includes borax, acid and sodium phosphate, silicic acid and charcoal. When welding copper with a closed arc,
special fluxes are used.

Copper products, and especially sheet material, can be arc welded using a copper electrode

. In this case, copper welding, including automatic welding, must be carried out under a layer of flux.

Brass

They are welded mainly with an acetylene-oxygen normal flame and an electric arc (carbon electrodes). When welding, the same fluxes and rods are used as when welding copper. Currently, automatic welding of brass with an electric arc submerged arc (copper wire) has been mastered.

Bronze

welded by gas, arc and argon-arc welding. Tin bronze at a temperature of approximately 600 ° C becomes increasingly brittle, so the welding process must be carried out on supports. The purpose of the linings is to remove excess heat in order to accelerate the cooling of the bathtub metal.

When gas welding bronze, borax is used as a flux, and when welding aluminum bronzes, AF-4a grade flux is used.

Date added: 2015-12-22; ;

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Benefits of use

Copper pipes as components of pipelines for various purposes are very popular today. In this regard, brazing copper, which uses a flux such as borax, has become a fairly common technological process. The use of this method of connecting copper products allows not only the installation of new pipelines, but also high-quality repairs of those that have already been in use for a certain time.

Borax removes the oxide film from the surface and promotes the spreading of liquid solder

The use of technical borax as a flux when soldering copper has the following advantages.

Metal parts in any combination can be subjected to high-quality soldering.
Metal products that need to be joined by soldering can have any initial temperature.
When using borax, high-quality and reliable connections can be obtained even between metal and non-metallic parts.
Soldered joints made using this flux can be unsoldered at any time if the need arises.
When soldering, the base metal does not melt, as happens during welding, which avoids such an undesirable process as warping (and, accordingly, changes in the geometric shape of the products being joined).
The use of borax allows for excellent adhesion of the solder and the surfaces of the parts to be joined.
Technical borax, used as a flux, provides high productivity for a process such as capillary soldering.
The solder joints obtained using this type of flux are characterized by high strength, reliability and durability.

Brazed copper pipes using borax as flux

To understand what factors influence the quality of soldering, you should know the stages of this technological process. The soldering algorithm is as follows.

The surfaces of parts that need to be connected by soldering must be carefully prepared.
Contaminants are removed using standard means - brushes, rags, etc. And to remove refractory oxide films from the surface of parts, a flux such as technical borax is used.
The surfaces of the products to be joined must be heated to a certain temperature, for which a blowtorch is used.
Liquid solder is introduced into the gap between the parts to be joined, which is also heated using a blowtorch or a regular gas torch.
The interaction of the heated base metal and liquid solder ensures a reliable solder joint.
The soldering process can be considered complete at the moment when complete crystallization of the solder occurs.

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How to solder copper elements using borax

It often happens that it is necessary to solder copper and copper pipes at home. Many water supply systems installed in modern homes are made from this material. When repairing such plumbing fixtures, it is desirable that the contractor is well acquainted with the necessary actions and the properties of the material.

When connecting copper elements, the advantages of brown soldering are as follows:

Hard soldering diagram.

the connection can be made regardless of what the initial temperature of the product is;
can be combined by soldering copper, that is, metal, with non-metals;
most of the resulting connections can be unsoldered if necessary;
parts and solder interact perfectly;
the shape and dimensions of the metal product are maintained quite accurately, because the base metal does not melt;
Capillary soldering can provide good strength and high productivity.

This type of soldering has a special technology, which makes it possible to obtain a connection in several steps:

surfaces intended for soldering are prepared for work;
Contaminants are cleaned from the surfaces of elements, the oxide film is removed, which requires the use of flux in the form of borax;
the elements being connected are heated to a temperature equal to the temperature at which the metal of the base material melts;
liquid solder is introduced into the gap between the parts;
interaction occurs between the parts and the solder;
the solder crystallizes.

How to solder copper pipes

Before you start soldering, you need to prepare the following tools and consumables:

brushes with metal bristles for cleaning joined surfaces;
devices and tools with which the parts to be joined will be cut to the required sizes;
gas burner or blowtorch;
solder, which is selected depending on what material the parts being connected are made of;
borax, the characteristics of which must meet the requirements of GOST 8429-77;
brushes necessary for applying flux.
Flux, solder and torch are the main components for soldering copper alloys

Particular attention should be paid to the choice of gas burners, which are presented in a large assortment on the modern market. Such a device, designed to ensure complete heating of the base metal and solder, can be equipped with automatic piezo ignition or manufactured in a classic design. You should only choose burners that use a piezoelectric element for ignition if such a device is manufactured under a well-known brand. Otherwise, it is better to purchase a regular high-quality burner that will provide you with uninterrupted operation for a long time.

Cleaning the joint before soldering

The soldering process itself using borax, including preparatory procedures before its implementation, is most conveniently considered using the example of connecting two pipes made of copper. This process is performed in the following sequence.

The internal surfaces of the connected pipes are thoroughly cleaned, for which a jaw with metal bristles is used.
External cleaning of copper pipes, carried out until their surfaces have a metallic shine, is carried out using emery cloth.
After thorough cleaning, borax is applied to the internal and external surfaces using a special brush.
Copper pipes coated with flux at the future connection must be joined together. After this you can start soldering.
Before starting the process, the pipe surfaces must be heated to the required temperature, for which a gas burner is used. The surfaces of the products to be joined should be exposed to flame for at least 15–20 seconds.
After the surfaces of the pipes are heated to the required temperature, solder is introduced into the soldering area, which also melts under the influence of the flame of a gas burner. Molten solder should be applied evenly to the surfaces of the parts to be joined to ensure the quality and reliability of the joint being formed.

Applying flux to the soldering area

After soldering using borax, the resulting connection should be inspected, for which destructive and non-destructive methods can be used. Most often, such control is performed when inspecting the resulting connection for the presence of external defects. A magnifying glass can be used to perform this inspection, which reveals many joint imperfections.

Tools and materials

To perform the work you will need the following equipment:

Cutter for copper parts (if necessary).
Brush for applying borax flux paste.
Tin solders.
Flux paste.
Burner.

Materials and tools for soldering.

Burners may be different. Some are equipped with piezo ignition, but there are also those that are produced without it; here the use of gas cartridges is provided. Expensive burners without ignition are not particularly popular. More often, Polish burners with piezo ignition are used instead - they cost little and better meet user requirements.

The procedure will be as follows:

the surface of the connection must be cleaned using a special brush, and if we are talking about pipes, internal treatment must also be carried out;
it is advisable to carry out a final cleaning using emery cloth so that the metal is polished to a shine;
Flux is applied with a brush - in this case borax - both on the outer surface of the joint and on the inner;
ensure that the parts are pressed: they are inserted into one another or pressed together.

Subsequent work must be carried out with special attention, since the performer is dealing with an open flame. The gas burner is ignited, then the connection is heated. It should be heated for 15-20 seconds.

Now you need to take the solder and process the edge of the connection with it. Three seconds are enough for the procedure.

To solder copper pipes or other elements, brass wire is used for the additive. Borax can be poured onto the soldering area. You can look at the process in more detail.

Step-by-step instruction

To prepare a solution of borax from soda and boric acid, follow these steps:

pour boric acid into a container;

Tetraborate from soda. Pour boric acid, add 1 teaspoon of soda to the acid;

Stir

stir the mixture until the soda is completely dissolved;
strain the finished mixture through a napkin to remove any remaining soda

What you get as a result is sodium tetraborate. Which can be used for its intended purpose.

To prepare a borax solution according to the second recipe, you will need:

pour 1 teaspoon of boric acid (borax) solution into a container;

Construction borax for tetraborate, add 4 teaspoons of glycerin to the powder;

Adding glycerin

Stir the resulting mixture until a clear liquid is obtained;

in order to obtain a more transparent solution, it can be placed in the microwave for half a minute.

Sodium tetraborate after microwave

The result is clear sodium tetraborate. Please note that the resulting solution is a chemical product and cannot be used for medical purposes. This sodium tetraborate is ideal for making handgam.

Soldering of metals 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 molten solder.

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

Advantages and disadvantages

Borax-based flux is very popular. This material is always on sale. For soldering copper products, borax is the most affordable flux with budget prices.

Depending on the elemental composition of the parts, you can use not only crystalline powder, but also a solution. Crystalline hydrate is highly soluble in water.

There are some difficulties when using borax. The solder area is covered with plaque after soldering is completed. It needs to 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 home.

Sodium tetraborate for slime

The substance sodium tetraborate is found in the children's entertainment toy slime. Knowing how to make sodium tetraborate at home, you can make a toy for your child from the substance. It will be no different from the store-bought version, but since it is a chemical, it is advisable to play with it carefully.

Homemade slime for your child will have more significant advantages compared to purchased options. To make a toy yourself, you first need to make a borax solution, and also prepare glue (preferably transparent), water and gouache, you can use food coloring.

Slime making process:

find a container and pour warm water into it;
add the prepared borax solution and mix the composition well;
after dissolving the substance, we find another container and pour half a glass of water, glue and dye into it, and then also mix as much as possible until a homogeneous mass of the same color is obtained;
now the mixture is poured in a thin stream into the container with the dye, but at the same time you need to mix the composition;

Ready slime

The result is a viscous mass that a child can play with, but you need to control it so that the baby does not put the slime in his mouth.

We discussed other options for making a child-safe slime toy in a separate article.

What is borax used for?

In medicine - aqueous and glycerin solutions of borax

used as an antiseptic external remedy for fungal diseases for skin treatment, mouth rinsing, douching. In agriculture and everyday life - an insecticide against all types of insects; included in microfertilizers.

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