Brass is an alloy whose essential components are copper and tin. Possessing high strength, ductility and corrosion resistance, it is well suited for the manufacture of both heavily loaded parts of various mechanisms, and structural elements operating in aggressive environments. Its main disadvantage is its high cost. But there are other problems associated with the use of this material.

To date, developed various technologies allowing welding of brass products. But all of them are quite complex, costly, and require the specialist performing the work to have certain skills. An alternative to welding is often brass soldering. It is somewhat simpler technologically and imposes different requirements on the qualifications of the performer.

Obstacles encountered

If the zinc content in the alloy is low, then no special problems arise. You can cope with the task using ordinary rosin. But in the case when the amount of zinc exceeds 15%, in mandatory requires the use of special fluxes. This is due to the fact that when zinc and copper evaporate when heated, they form a strong oxide film on the surface of the part, which is very difficult to remove.

Choose a ready-made one or make it yourself?

The simplest flux for soldering brass is easy to make yourself. To do this, you will need to mix borax powder and boric acid, pour the resulting amount with water at the rate of 5 ml for each gram of powder mixture, gently stirring, boil, and then cool. But best characteristics ready-made formulations available for sale have.

• One of the most common is Borax flux. Invented a long time ago, this recipe has received the approval of many soldering jewelers. different metals, including brass. It belongs to the category of high-temperature mixtures, activated when reaching 700 - 900 degrees Celsius. Despite his advanced age, he performs his work efficiently.
• Fluxes of the PV-209 and PV-209X brands do their job well. The first is based on fluorosalts, and the second is made using hydrofluoric acid. Both also operate at temperatures approaching a thousand degrees.
• The compositions Chemet FLISIL-NS-Pulver (powdered) and Chemet FLISIL-NS-Paste (paste) produced in Germany will require slightly less heating. For them, 550 - 800 degrees Celsius will be enough. They work best when using silver-containing solders.

The brands listed are provided as an example only. There are many options on the market for these brass soldering essentials.

Which solder should I take?

No less important than the choice of flux is the determination of the desired solder composition.

• For soldering brass with copper content, PMC-48 solder is well suited, melting at 870 - 880 degrees. PMC-36 has a slightly lower melting point. Both compositions belong to the group of copper-zinc solders.
• Grades MF-1, MF-2 and MF-3 belong to the group of copper-phosphorus solders. They are relatively inexpensive, ductile, but have high electrical conductivity and resist shock and vibration loads worse than compositions containing silver.
• Silver solders have the best mechanical properties. Among them are PSr-10, PSr-12m, PSr-25 and further, up to PSr-72. They all have some differences, which are chemical composition and melting temperature. They also react differently to the percentage of copper and tin in the metal being joined.

From the above, it is clear how important it is to decide on the brand of brass before choosing flux and solder. Only then will it be possible to achieve an acceptable soldering result.

Preparation

Before starting work, it is necessary to thoroughly clean the connection area from dirt. For this you can use the most different instruments– metal brushes, special attachments, files or sandpaper. After this, the treated metal must be degreased. Without doing this, you will complicate your work, and the soldering, even if it can be done, will not have sufficient strength.

The parts to be soldered must be placed on a thermally insulating pad. It’s strange, but many sources still recommend sheet asbestos, recognized as a carcinogen, for these purposes. There is no doubt that it is worth finding a replacement that is not harmful to health. For example, based on fiberglass or carbon fiber.

Soldering iron or torch?

The use of an electric soldering iron is acceptable when flux and solder with a melting point of about 500 degrees Celsius are used. But even in these cases, the power of the device must be at least 100 watts. It is better if this figure is 0.5 kW and higher. After all, the soldering area must be well heated beforehand.

It is more convenient to connect massive parts or solder thick brass using a gas torch. In this case, it is possible to heat the metal so that the use of high-temperature components becomes possible. The connection area is treated with flux and sprinkled with crushed solder on top. Only after this they proceed to heating the metal. This must be done extremely carefully. First, preheating is performed to activate the flux and allow the solder to adhere to the surface. The temperature is gradually increased until the brass acquires its characteristic redness. It is at this moment that the solder spreads, filling all the small pores in order to reliably connect the parts when cooling. If everything is done correctly, then after gradual cooling you will get a neat seam, the color of which will be close to the color of brass.

Scope of application

It is quite obvious that soldering brass is easier than welding, not only at home, but also in production. The resulting connection will have sufficient strength. However, it can be expected to withstand very high loads, still not worth it. Based on this, the scope of application of the technology is determined.

• Manufacturing of electrical and electronic components. Mechanical loads in this case are low, and electrical conductivity comes to the fore. Don't forget how difficult it is to use welding to connect small parts.
• Connection of elements subjected to low and medium loads. This may include parts of small mechanisms such as watches, or components of pipelines operating at a pressure not exceeding several atmospheres.
• Jewelry production. Of course, the cost of brass is much lower than silver or gold. And yet, it is quite often used to make inexpensive rings, brooches and other jewelry, becoming, if not their main part, then at least a component of frames and clasps.
• Don't forget the restoration work. Sometimes soldering brass - the only way restore something made many years ago.

This technique has also been used in mechanical engineering. Using it, making a new one or soldering a damaged brass radiator is much easier than using welding. The efficiency and durability of the resulting part will be significantly higher than that of cheaper aluminum analogues.

Taps, hardware, pipes are made from brass, decorative items interior and many other products. This material is obtained by fusing copper, zinc (in different proportions) and various additives.

Soldering brass ensures a reliable and quality connection details. Soldering involves the use of a special tool in the form of a gas torch, as well as solder made from a mixture of tin and lead. In some cases, tin alone is used to make brass solder.

Subject to availability necessary tools and materials, and after learning the basic techniques for handling brass, you can start soldering this material yourself.

Soldering brass products has several features. This technology involves the use of specially prepared solder, which is introduced into the gap between the parts and plays the role of a “grasping” element. In addition, the equipment through which the solder material is melted is essential.

Typically, a gas torch is used for soldering, which ensures that the solder wire melts at temperatures lower than the melting point of the brass itself. Using this technology, it is possible to reliably solder individual workpieces of similar or dissimilar materials in structure.

In some cases, the use brass soldering- that's the only thing possible way obtaining permanent contacts.

It is unacceptable to compare soldering with welding procedures in which each of the metals being fused is subject to melting. IN in this case Only hard solder with tin is exposed to thermal effects, and the condition of the parts being connected remains unchanged.

This feature allows you to process brass products completely small size and the masses without causing them any damage.

When carrying out soldering, it must be taken into account that this process involves the use of softer consumables than when welding. As a result, the joints obtained by soldering are considered less strong compared to welded seams.

In cases of working with brass, zinc completely evaporates from the solder body (due to its strong heating), as a result of which the seam becomes porous, which significantly reduces the quality of the joint formed.

In addition, when soldering brass parts, it is important to correctly select their relative position (in this case, preference is given to “overlapping” joints).

Application

Modern technologies for processing copper and zinc alloys are widely in demand in such industries as:

• electronics and electrical engineering;
• instrument making and tool production;
• production of refrigeration and ventilation equipment.

If you have everything you need (solder of the required quality, flux and soldering torch), brass surfaces can be tinned to protect them from corrosive destruction. The tinning procedure is also in demand when repairing heating and plumbing systems, made on the basis of brass.

Depending on the type of solder used for soldering, connections are divided into high- and low-temperature. This division allows the use of more refractory joints for soldering workpieces operated at high temperatures.

Use is not possible at home, since this situation requires special equipment.

Features of soldering homogeneous workpieces

IN living conditions Often there is a need to solder two brass blanks of the same structure. In this case, the correct choice of flux composition, which differs from the traditional combination of rosin and alcohol, becomes of paramount importance.

Due to the low activity of the components, a conventional composition will not be able to dissolve the oxide film that forms on the surface of brass. So for the soldering option under consideration, a more active flux based on chlorine and zinc will be required.

All the details of its preparation can be found in the table, which shows several types of zinc chloride mixtures.

In addition to the types of flux considered, when soldering brass, compositions based on borax and potassium fluoride-boron salt can be used. Mixtures prepared from them occupy no more than 5% of the total volume of the solder bath and have excellent activity indicators.

Activity refers to the ability to create ideal conditions for penetration of molten solder into the gaps between parts during soldering.

Along with the problem considered, we should not forget about a competent approach to the selection of solder supplied to the joint in the form of calibrated wire of one composition or another.

In the case where soldered brass products are intended to be used in a gas environment, it is advisable to use special types of solders made on the basis of copper phosphate and silver alloys. They are also suitable for soldering red brass with large percentage copper component.

Sometimes wire made from brass itself is used as solder. However, in this case, it is possible to solder a brass part only if the melting point of the brass wire is lower than the same indicator for the workpieces being processed.

General procedure

Before you start soldering brass parts yourself, you should thoroughly clean them of foreign deposits and contaminants. Next, you need to place them on a fire-resistant substrate, the function of which can be performed by river pebbles poured into an old bucket.

The general procedure for soldering brass can be represented as follows.

During the soldering process, overheating of the workpieces is unacceptable, which can cause their deformation. In general, independent brass soldering is not something completely inaccessible.

To master this technology, it is enough to correctly select all the necessary consumables and follow the given recommendations exactly.

In our practice we often have to deal with brass parts. They are well processed, soldered and then blackened. Most people solder brass with a soldering iron using regular tin solder. This method, along with its simplicity, has three serious drawbacks: the seam turns out white, noticeable, and few people manage to immediately make this seam thin; the seam turns out to be relatively weak; when bent, it can easily come apart; When blackened, tin may behave differently than brass and the weld will turn out to be a completely different color or shade. This article will tell you about the method of soldering brass using a gas torch with special solder and flux. The resulting weld is practically indistinguishable in color from the main parts, very durable and chemically much closer to brass than tin.

For soldering you need:
- gas burner;
- asbestos base;
- graphite crucible (bath);
- silver;
- copper;
- borax;
- boric acid.

First you need to make solder. It will consist of 2 parts silver and 1 part copper. You need to fuse silver and copper (where can you get silver? - Do you know silver spoons? They are perfect). This can be done using the same gas burner. We weigh out the amount of silver and copper we need, place them in a graphite crucible and heat it with a burner. The crucible can be made from trolleybus contacts; there are a lot of them lying around at the final stops. The crucible size is approximately 20x50mm. A 5x40mm semicircular groove is selected to make it easier to remove the resulting bead of solder; to do this, lower the still hot crucible into water. When both metals melt, mix them with a steel wire - a hook. In principle, you can first melt copper (as a more refractory metal), and then add silver to the melt. Or vice versa - whoever likes it more.

The arrow shows the graphite bath. It is located in a brick "furnace".

That's it, the solder is ready. Let it cool, roll it out in a roller or flatten it on an anvil, then cut it into small pieces. You can simply grind the casting into shavings with a coarse file.

Now the flux. Take about 20 grams of borax (powder), the same amount of boric acid (powder), mix and pour a glass of water. Boil (to better dissolve the ingredients). That's it, the flux is ready. This amount of flux will last for the rest of your life. There is no need to worry about it being chemically hazardous. Boric acid is quite passive and does not harm your fingers or tools. In principle, you can evaporate the water, calcinate the already solid flux, crush it into powder and mix it with solder. The result is a dry mixture of solder and flux. But this is not for everybody.

Soldering process. You need to solder on something heat-resistant. Plates from the Buran's skin are best suited for this. But if Buran doesn’t fly over you, then you can get by with an asbestos plate. We place our parts to be soldered on it, moisten it with flux, sprinkle it with solder shavings (you only need a little bit of it) and begin to slowly heat it up. First, a little bit, so that the solder grabs the parts being soldered a little, then until red (approximately 700 degrees for this type of solder). Solder easily flows into the cracks between the parts and solders them tightly. At this stage, there are the following dangers: since the difference in the melting temperature of solder and brass parts is only about 50 degrees, you must be careful not to overheat them. Otherwise you will just get one big ingot. We must remember that small parts (for example, brass wire) heat up much faster than massive ones. Therefore, be careful. In this case, it is necessary to heat the entire structure slowly so that the large part has time to warm up.

The parts became red hot.

The resulting seam has almost the same color as the parts being soldered. This occurs because soldering causes diffusion of the base metal into the solder. Therefore, the same solder can be used when soldering silver - the seam will be white.

The last stage is washing the product from flux residues, which remains on the product in the form of glassy drops and sagging. To get rid of them you need finished product rinse in hot 3% sulfuric acid (or 15% when soldering gold). You can do this on gas stove, placing a quartz glass test tube with dilute acid on it. The product is simply lowered into it for a short time (it must first be tied to something that does not interact with acid) and then washed with running water.

I foresee the question: “Why can’t I use a soldering iron?” The answer is very simple: the melting temperature of solder is about 700 degrees, and a soldering iron can only give 200-250 degrees.
Those who have not used a gas burner before may ask, how long does a gas cylinder last? At normal use Consumption can be calculated at the rate of 1 liter per year.

In previous materials we looked at electric soldering irons and gas burners used in soldering, and also became familiar with solders and fluxes.

Important!!! For all work on food equipment, ONLY LEAD FREE solder should be used.

Do not forget that when soldering, hot objects, aggressive liquids, and a voltage of 220 V are used. Be extremely vigilant and exercise caution.

In this material, let's move on to practice and solder copper. Along the way, let's look at the features of its soldering.

Soldering copper and brass are not very different from each other. The main difference is thermal conductivity, which is several times higher for copper. Therefore, brass is even a little easier to solder.

Copper and brass are soldered with tin solder; rosin, orthophosphoric and soldering acid are used as flux. You can solder with aspirin, but this is a last resort.

I prefer to solder copper with phosphoric acid, and it does not have to be stripped mechanically.

Let's look at the example of soldering two copper tubes together.

First, you need to widen one of the ends. I used thin-nose pliers for this purpose.

On the contrary, we sharpen the second end a little so that it fits into the widened part.

Before soldering, the contacting parts of the tubes must be tinned, that is, covered with a layer of tin. Yes, not just to cover, but to cover with high quality, so that the metals do not peel off from each other. To do this, the surface to be tinned must be heated no lower than the melting temperature of the solder. And since copper has a very high thermal conductivity, it will be very difficult to heat even a not very thick tube with one soldering iron.

I use a gas torch to preheat, and then quickly apply flux and use the soldering iron tip to apply and spread the solder.

At the same time, overheating a part is just as bad as not heating it up. I go by the color of copper; as soon as it starts to darken a little, that’s enough.

A well-tinned surface has a uniform shine and does not lag behind the tube even with strong scratching.

Brass soldering has own characteristics due to the evaporation of hot zinc, as well as the formation of an oxide film on the metal surface. Brasses containing up to 15% zinc are oxidized by a film, which consists of interlocked particles of CuO and ZnO. In copper alloys containing sufficient large number zinc, the oxide film consists mainly of ZnO, which is much more problematic to remove than in the case of a copper oxide film.

The following tools and materials are useful for soldering:

• Asbestos base;
• Gas burner;
• Graphite crucible;
• Copper, silver, borax, boric acid.

Preparing solder

First you will need to make tinol at home, which will consist of silver and copper in a ratio of 2:1, respectively. To do this, you need to fuse silver and copper using gas burner. Next, you need to weigh out the required amount of silver and copper, after which they must be placed in a crucible and heated with a gas burner.

A graphite crucible can be produced from graphite coals (contact trolleybus elements), which are not difficult to find at the final stops of electric transport. Regarding the size of the crucible, it should be approximately 20x20 millimeters.

Then we select a 5x40 millimeter semicircular groove to make it easier to remove the solder bead (the hot crucible is lowered into the water). Once the copper and silver are melted, you can begin mixing the tinol components using a wire.

Preparing gumboil

Thus, the solder is ready for use, but it still needs to be cooled, rolled out in a roller, and also cut into small pieces. Now you need to start preparing the flux. To do this, take 20 grams of borax (powder), as well as an equal proportion of boric acid (powder), then thoroughly mix the ingredients and pour a glass of water. Next, boil and cool the finished flux.

We work as follows:

1. You need to solder on some heat-resistant material. If you are soldering radiators, do the work thoroughly. For this purpose, we stocked up with asbestos plate. Thus, we place it on non-soldered parts, then moisten it with flux and sprinkle it with solder. Next, we begin to warm it up little by little.
2. First, we heat it a little so that the solder adheres to the parts, after which we complete the procedure until a red tint appears.
3. The solder quite simply flows into the gap between the parts, soldering them together very tightly. It is worth paying attention to the fact that the difference between the melting point of brass and solder is about 50 degrees. C, and therefore the material should not be overheated.
4. The resulting seam has one distinct color with the part being soldered.
5. This is followed by washing the product from flux: we wash the product in hot sulfur acid (3%).

Thus, we get excellent adhesion of brass products that will last for many years.