Iron copper plating. Metal plating with copper at home

Surface treatment of various objects is carried out to give decorative effect or as an interim procedure preceding further steps. Many processes are available for execution and do not require a lot of equipment. One of the most popular processing methods is copper plating, which can also be done at home.

What is the copper plating process

Copper plating is the process of applying a thin layer of copper to the surface of an object. It is performed by the galvanic method, i.e., by transferring copper ions from a positively charged source to a negatively charged surface to be treated. Most often the process electroplating copper is preparatory stage before coating with nickel and chromium, but often copper plating of metal becomes an independent type finishing. Electroplating is widely used, for which it is required to create a coating of copper.

Varieties of copper plating

There are two options for copper plating at home:

• With immersion of the workpiece in the electrolyte.
• Without immersion.

With immersion of the workpiece in the electrolyte. To perform the procedure, you must have a container with an electrolyte that has a sufficient volume. After preliminary preparation, consisting in cleaning the surface sandpaper and washing in a hot soda solution, the object is connected to the negative electrode and immersed in the electrolyte for a certain time.

Without immersion. Can be processed steel, aluminum, lead, zinc. Processing is carried out without immersion in a container, usually this option is used for large parts.

Both options are available for self-fulfillment at home.

Equipment and materials needed for copper plating

To perform copper plating of steel or other metals, you will have to stock up on some materials and devices. You will need:

• Copper sulfate (copper sulfate).
• A DC source, preferably with a regulated voltage (one option is LATR), but a conventional 6–12 V transformer will also work.
• Capacity for electrolyte (optimally - a glass tank).
• Two copper plates that can fit freely in the container.

Out of the water, blue vitriol and hydrochloric acid it is necessary to make an electrolyte. First, copper sulfate is added to the water until a saturated solution is obtained. It must be thoroughly mixed so that no solid particles remain. Then, in a thin stream, add hydrochloric acid(not vice versa!). In total, for coating you will need:

• - 980
• - 190
• - 40 g.

Now everything is ready, you can start copper plating at home.

Attention! It must be borne in mind that hydrochloric acid is a chemically active reagent, so you should stock up on protective equipment - gloves, goggles, prepare as much as possible workplace.

Copper plating technology

Procedure for coating application:

• It is necessary to remove a thin film of oxides from the surface of the part to be processed. Sandpaper, wire brush or other abrasive materials. It is necessary to act very carefully, since severe damage to the metal will remain noticeable. Ideally, the surface should be polished.
• Then the product is thoroughly washed in a hot solution of soda ash. This action allows you to degrease the surface.
• The prepared product is connected to the negative electrode from the power source and placed in the electrolyte solution.
• Copper plates with a positive electrode attached to them from a power source (anode) are lowered into the electrolyte solution. It is necessary to ensure that the anode and cathode do not touch. Ideally, the distance between them should be the same in all areas, but in practice this is difficult to achieve.
• Copper plating of metal is carried out in several steps. The first layer of coating obtained within a few minutes, it is recommended to remove and rinse the part again in soda solution. This will enhance the adhesion of the copper plating layer to the base metal. The item is kept in the solution for about 20-30 minutes. The thickness of the coating layer can reach 300 µm.

It is often necessary to remove a layer of coating from chrome parts. To do this, a negative charge is applied to the part, and a cloth soaked in a solution of sulfuric acid (5%) is wound around the positive electrode. It wipes the surface of the part, the chrome layer is removed. When performing the procedure, it is necessary to protect the skin, organs of vision and breathing from acid vapors.

Copper plating of parts without immersion in solution

Galvanic copper plating can be performed without immersing the part in a container with electrolyte. To do this, connect a negative electrode to it. A copper stranded wire is taken as a positive contact, the end of which is freed from insulation by 1–2 cm and kneaded so that a kind of brush is obtained.

To apply a layer of copper coating, the “brush” is dipped into the electrolyte, then its end is drawn along the surface of the part, without touching it, but trying to have a layer between them. Constantly dipping the anode in the electrolyte, cover the entire surface with a layer of copper. The procedure requires skill and time, but the result is worth it.

Electrotype

Copper plating can be done not only on metal objects. Electroplating is widespread, when copper plating is performed on various dried plants, insects and other non-metallic objects.

The coating technology differs little from the usual one, only at the beginning of the process it is necessary to apply an electrically conductive varnish to the surface. After the varnish has dried, the usual steps are taken to apply a layer of copper. The resulting products have high decorative or artistic qualities and are highly appreciated by the audience.

To change the appearance of an object or improve its physical properties, this object is covered in a special way with a thin layer of copper, chromium, silver. Sometimes this is done to improve the conductive properties of the metal (for example, copper plating of steel), sometimes to imitate the antiquity of an object (for example, a figurine), sometimes simply to give the product a more aesthetic appearance.

Copper plating of materials and its use in everyday life

Copper plating is the coating of the surface of any product with a thin layer of copper. This layer can be from one to 300 or more micrometers thick. In everyday life, this process is used in a variety of circumstances. Copper plating at home will give the product an "old" look, turn the steel strip into an excellent conductor, and prepare the object for applying another coating.

Varieties of copper plating processes

Coating surfaces with a layer of copper is a process that can be carried out not only in industrial plants, but also in the home workshop. Copper plating of metal at home can be done on your own high level. It is only necessary to study the main features of the technology and observe safety precautions. There are two technologies for copper plating the surface of objects.

First technology- "submersible", with the use of an electrolyte solution. In this technology, the workpiece is immersed in an electrolyte between two copper electrodes. After that, voltage is applied to the electrodes and to the workpiece. After some time, the part is covered with a thin layer of copper. The longer the product is kept under voltage, the thicker the copper layer on its surface will be.

Second technology- without immersing the workpiece in the electrolyte. This technological process is more complex than dipping copper plating of steel or any other metal, but, nevertheless, gives excellent quality of surface coating with a copper film.

Features of the process of copper plating steel at home

To produce copper plating at home, it is necessary to fulfill a number of requirements arising from the very technological process, since the immersion method involves the use of an electrolyte. This solution is caustic, subject to evaporation, and since during operation it will also heat up, the evaporation will be intense. For electroplating at home, you should take care of protective equipment and good ventilation.

Electroplating with copper at home, despite the rather primitive equipment, nevertheless gives excellent results. Of all metals, steel provides the most strong connection with a copper film, therefore, it is during copper plating of steel that excellent, durable current conductors are obtained. Coating a steel product with a copper film will give the item a more attractive look.

Before starting the copper plating process, you should prepare your home, workplace, necessary materials and personal protective equipment for these works. After that, you should prepare the workpiece. The oxide film should be removed from its surface with a thin emery and a fine metal brush. After removing the film, the part is washed, degreased in warm soapy water and washed again with clean water under strong pressure.

Scheme of copper plating of steel in electrolyte

Two copper plates are placed in a container (preferably glass), electrically connected to each other. These plates are anodes, and are connected by a conductor to the plus of the current source. A conductor is connected to the minus of the source, connected to the workpiece being processed, which is the cathode in this circuit. A rheostat is included in the anode circuit to adjust the current strength and an ammeter for control.

The prepared electrolyte solution is poured into the container, which includes copper sulfate, distilled water and acid. The solution is poured in an amount sufficient to completely cover the electrodes and the workpiece. Voltage is applied to the circuit, a current is set by the rheostat at the rate of 15 mA per square centimeter of the part area.

After half an hour, the voltage is removed, the copper-plated part is removed from the solution, freed from the conductor, thoroughly washed, and dried. Process completed. Necessary note: all operations should be carried out in a respirator, rubber gloves and with ventilation turned on.

Preparation of a solution for home copper plating

For electroplating at home, except for electrical equipment(DC source, rheostat, ammeter), it is necessary to prepare an electrolyte solution in which the process will take place. To prepare such a solution you will need:

• CuSO 4 - copper sulfate;
• acid - HCl (hydrochloric), or HNO 3 (nitric), or H 2 SO 4 (sulfuric);
• distilled water.

Depending on the required amount of electrolyte, a solution is prepared in proportion to 100 milliliters of distilled water:

• copper sulfate - 20 grams;
• any acid - from two to three milliliters;
• distilled water - 100 milliliters.

To obtain a larger amount of solution, the amount of ingredients increases proportionally.

Necessary equipment, tools, protective equipment

For copper plating at home, it is necessary to prepare the appropriate equipment, tools, personal protective equipment. The equipment includes, first of all, a direct current source. Such a source can be KBS batteries with a voltage of 4.5 volts or nine-volt Krona batteries. It should be borne in mind that when copper plating parts with a large surface area, the power of these batteries may not be enough.

In this case, you need to use several of these batteries. You can use a car battery or a small 12 volt rectifier. You will also need a small rheostat or a powerful power variable resistor. Of the devices you will need an ammeter or a conventional tester. You will also need an exhaust fan.

From the tools you will need emery, pliers, crocodile clips with soldered conductors to grip the anodes and the workpiece, a fine metal brush.

A container made of a neutral material that does not react with the solution should be prepared directly for copper plating. A container for preparing the solution should also be prepared.

From personal protective equipment, rubber gloves, a respirator and neutral glasses should be prepared.

The process of copper plating without the use of a solution

Home copper plating of steel can be done without immersing the part in an electrolyte solution, although not a large number of You still need a solution. This method is effective not only for steel, but also for products made from other metals. Preparation for copper plating and the process itself take place as follows.

The workpiece is cleaned of the oxide film, degreased, a conductor connected to the minus of the current source is connected to it with an alligator clip.

A copper wire with a diameter of one and a half millimeters is stripped of insulation and threaded into the bristles of a toothbrush so that it is inside the bristles. The other end is connected to the positive terminal of the current source. The current is turned on, the brush is wetted in the solution, after which the brush is driven over the surface of the workpiece.

Periodically, the brush is moistened again in the solution. The operation is carried out until the object is completely covered with copper.

Carried out by many craftsmen in the first place in order to prepare the surface of the metal for subsequent processing with various protective layers.

This operation can be applied to the surfaces of a wide variety of metals and non-metals, including steel, brass, nickel, and so on.

Mankind has been using copper for its own purposes for many millennia and this is due primarily to the fact that this metal is found in nature in a native state, and besides this, it has a number of unique properties.

Currently, copper and a variety of alloys based on it are in demand in many industrial areas.

Aircraft, automotive, instrumentation and many other industries cannot do without it.

Copper and its numerous alloys are quite common in the domestic sphere.

It should also be noted that copper additives in various combinations can effectively protect the surfaces of many metals, such as steel, brass or nickel, from various aggressive media.

One of the most common ways to thin a metal surface is to apply copper.

At home, in most cases, chemical copper plating is performed, and there are several various ways, each of which has its pros and cons.

One way to do copper plating at home is shown in the video below.

As mentioned above, in nature, copper, as a rule, is in the form of small nuggets.

This unique substance is a fairly heavy metal that looks like a bright pink-red nugget.

This metal has a relative softness and high malleability, in addition, it has a melting point of the order of one thousand one hundred degrees Celsius.

It perfectly conducts not only heat, but also electricity, which explains the increased demand for this metal in electrical engineering and instrument making.

In most cases, in nature, copper is not in a pure state, but with various impurities.

All kinds of natural additives, depending on various factors in the metal, can vary and vary from approximately ten to fifty times.

For this metal, the content of oxygen in it is of great importance, and depending on the amount of this element in the composition of copper, a certain classification has been developed.

So, copper can be oxygen-free and refined.

In addition, there is copper with a high oxygen content in its composition, as well as general purpose when the oxygen content is at its maximum.

In addition to this element, this metal can also contain hydrogen, which gets there due to electrolysis or annealing.

Copper has a certain crystal lattice, and hydrogen atoms occupy space in it at interstices, which means that they have practically no effect on its properties.

If copper in its composition contains oxygen in a certain amount, then hydrogen tends to interact in a certain way, but only at sufficiently high temperatures with copper oxide, and in this particular case, water vapor begins to form, which has enough high performance pressure.

It renders Negative influence on the metal as a whole and can lead in some cases to the formation of blisters, as well as cracks and breaks.

Such a negative effect among chemists was called hydrogen disease.

The presence of iron and antimony can affect the change in the ductility of copper for the worse.

Those impurities that belong to the group of poorly soluble ones reduce the brittleness of this metal, but only at sufficiently high external temperatures, which means that the hot pressure treatment process is highly undesirable for copper.

The video above shows the chemical copper plating of this metal.

Features of copper plating

To perform copper plating on the surface of steel, nickel, or some other metals, electroplating is used, in which a thin copper layer is formed.

Electroplating copper is a rather complex chemical copper plating, which affects the composition of the material.

Electroplating is a preliminary, before a different protective composition is applied to the surface of nickel or other metal.

Copper plating of lead and other materials is usually done before chrome plating, nickel plating, and so on.

In this case, copper acts as a kind of solder or, in other words, an additional additive.

How electroplating is performed independently is shown in the video below.

Copper deposited in this way as a solder on the surface of nickel or any other metal is able to hold quite firmly, and in addition, it helps to eliminate some defects.

On the surface thus treated, many other materials are deposited quite well as solder.

Such copper coatings as solder practically do not change the composition of the original metal and are characterized by high adhesion, good electrical conductivity, and ductility.

Copper is a kind of brightener in the form of solder, which practically does not change the original composition of the metal and acts as a kind of additive.

The main method of applying this metal (solder) to the surface of nickel, steel, and so on is electroplating, and the video below tells how to do this at home.

Application methods

To perform copper plating at home, you do not need to have any specific knowledge, you just need to know the course of school chemistry.

Due to copper plating, the surfaces of nickel or other materials do not change their basic composition, since it acts as a kind of solder.

Copper plating at home will require fairly primitive materials that can be purchased at any specialized store.

The copper plating procedure as solder can be performed with or without immersion in copper plating electrolytes (solution).

In both cases, before proceeding with copper plating, the workpiece must be properly prepared.

To do this, it is passed with sandpaper, carefully rubbed with a brush with metal bristles and washed under running water.

In addition, copper plating should be switched to after the workpiece is degreased, for which a soda-based solution is used in a heated state.

Between these anodes, a workpiece to be processed is placed, which is connected to the minus, respectively, the anodes to the plus of the DC source.

Also, for copper plating, a rheostat must be included in the circuit.

After that, to perform copper plating at home, they prepare special composition electrolyte solution with copper sulphate, sulfuric acid and water in certain proportions.

After copper plating, the sulfuric acid compound is drained, the workpiece is washed and thoroughly dried.

The video below shows the copper plating process at home.

Copper plating of aluminum, copper plating of steel or zinc is carried out by a method without immersion in the composition of the electrolyte.

In this case, the part is also prepared for copper plating by careful processing and washing.

For convenience, a handle is made on the wire and one of its ends is connected to the plus of a constant current source.

After that, to perform copper plating, a special electrolyte is prepared - a solution with the addition of copper sulfate and poured into a container.

After that, the solution is connected to a voltage and with the help of a brush they begin to process the part, thus applying a brightener.

The entire workpiece (solution) is subjected to the copper plating process for several minutes.

Upon completion of copper plating, the solution is removed, the part is washed and thoroughly dried. The process of copper plating without immersion in the electrolyte is shown in the video below.

Almost any metal can be subjected to copper plating, thus applying a protective coating in the form of a copper layer on its surface.
Video:

Modern technology puts forward stringent performance requirements structural elements, in many cases these problems are solved by chemical copper plating. The use of special coatings on the surfaces of parts is economically beneficial, since galvanic copper plating makes it possible to reduce the metal consumption of products made of expensive metals.

Physical and mechanical characteristics of copper and the scope of copper plating

The density of copper is 8.96 g / cm 3, the atomic mass is 693.54, the specific electrical resistance 1.68×10 -8 Ohm×m, melting point +1083°С. On the outdoors in the presence of aggressive chemical compounds, copper oxidizes; upon contact with sulfur compounds, it becomes covered with a film of copper sulfide of dark brown or gray shades. Under the influence of carbon dioxide and moisture, the film acquires green color, the upper layer consists of bicarbonates. Copper dissolves easily in a solution of nitric acid, dilute sulfuric acid has almost no negative effect on chemical copper plating. But the presence of oxygen increases the rate of chemical reactions. In the presence of open pores in the coating, a galvanic couple is formed, which must be taken into account when copper plating. Iron in this case is the anode, corrosion processes proceed very intensively.

In connection with such features, the copper plating process in most cases must be completed with additional surface treatment. Coatings are sanded or polished to a mirror finish. Copper has high adhesion with various metals: aluminum, silver, zinc, nickel, lead, chromium, etc. In connection with these features, chemical copper plating is often used to create a sublayer for silvering, nickel plating, and chromium plating of parts surfaces. Copper plating has become widespread as a method effective protection separate sections of parts from the appearance of the effect of carburization during the carburizing process. Depending on the purpose of parts or products, galvanic copper deposition can have the following thickness:

Comparative indicators of solutions

In the copper plating process, a large number of special technological solutions are used, divided into two large groups:

• A simple acidic electrolyte. Of the simple ones, a fluoroborate, silicofluoride, sulfate, chloride and sulfamide solution is used.
• complex electrolyte. Predominantly alkaline, copper is present as positively or negatively charged complex ions.

The deposition process in acidic electrolytes occurs at a high current density, they are stable, simple in chemical composition. The main components are the corresponding acids and salts, copper deposits from them are quite dense and have a coarse-grained structure. Disadvantages - direct copper plating of steel, zinc alloys and other metals occurs with a lower negative potential than copper.

Processing of parts in complex electrolytes is carried out at the expense of complex ions, they require high cathodic polarization. The current output is less, which contributes to a more uniform deposition, the structure is finely crystalline. Pyrophosphate, cyanide, ammonium, tripolyphosphate, citrate and other solutions are used.

Simple acid compounds

1. Sulfate. The main components are sulfuric acid and copper sulfate. Sulfuric acid compound is characterized by low electrical conductivity; sulfuric acid is added to increase the parameter. The current yield of copper reaches 100%, no hydrogen is released at the cathode. By increasing the concentration of acid, the solubility of sulfate decreases, which lowers the upper limit of the maximum allowable current density.

With stirring, the concentration of copper ions on the cathode layer increases. With an increase in temperature, the solubility of copper sulfate increases, the electrolyte increases the acidity, which leads to the formation of fine crystalline precipitates.

Surfactants are added to the electrolyte to improve cathodic polarization. Additionally, they reduce the formation of build-up on sharp edges.

For the formation of a brilliant coating, AMF anodes that do not allow the formation of sludge, or anodes from highly pure refined copper are used.

Fluoroborate electrolyte.

To prevent the ingress of sludge, the anodes are placed in covers made of acid-resistant material, in addition, the solution is constantly filtered.

1. Fluoroborate. They are highly resistant, the plating is dense and finely crystalline, the scattering characteristics are the same as with sulfate copper plating. Due to the high solubility, the current density increases; it is impossible to deposit copper directly on the parts.

With continuous stirring, it is allowed to increase the current density. Control of technological parameters of copper plating is carried out by measuring the acidity of the solution. Sodium carbonate is used to improve the quality of copper plating, and copper sulphate is used to lower it.

1. Nitrate. The electrolyte is used in electroforming, provides higher quality draft.

Modes and composition of nitrate electrolytes

Complex electrolytes

1. Cyanide. The processing conditions are significantly different from acid precipitation, in which copper exists in the form of complex ions, which significantly reduces its activity. Increasing the current density forces the cathode potential to shift sharply in the field of negative values. But the copper plating process cannot be carried out at an increased current density due to the fact that the copper yield can drop to zero. The main components of the solution are free sodium cyanide and complex potassium cyanide. During operation, the copper content decreases due to their insufficient solubility.

Mode and composition of cyanide electrolytes for copper plating

1. Pyrophosphate. Copper deposits have a fine-grained structure, smooth, shiny or semi-shiny. To improve the quality of processing and increase the cathode and anode densities, copper sulfate can be added. The cathodic potential in pyrophosphate solutions has more negative parameters than in acid ones.

Mode and composition of pyrophosphate electrolytes

1. Ethylenediamine. The copper plating process can be carried out directly on the steel surface; at low current densities, the cathodic polarization reaches large values. Scattering characteristics are higher than those of sulfate, but lower than that of a cyanide solution.

Mode and composition of ethylenediamine electrolytes

1. Polyethylenepolyamine. During the processing of parts, the potentials are shifted in the field of negative values, the electrolyte is used instead of cyanide.

1. Ammonium. The composition includes ammonia, ammonium sulfate and copper sulfate. At low current densities, the current efficiency decreases, copper plating is improved by adding ammonium nitrate. Precipitation is uniform in thickness, dense and semilustrous.

Without special surface treatment, copper deposits have insufficient adhesion, the reason is the passivation of steel with an ammonia solution. Improving the parameters of the coating is achieved by introducing copper nitrate into the solution.
Copper plating bath device Linear parameters and design features must meet the requirements of GOST 23738-85. is made of modified highly resistant plastics, specific grades are selected taking into account the parameters of technological processes.

Bathtub without pocket

Bathtub with pocket

The specific choice of copper plating bath is carried out depending on the characteristics of the enterprise, the characteristics of the parts to be copper-plated and the total production capacity.

During the design, the maximum loads are calculated taking into account the volume of the solution, the length, height and width can be changed at the request of customers. If necessary, additional equipment and plumbing fittings are installed on copper plating baths. Due special arrangements improves the quality of the copper plating process. The plastics used are adapted to the chemical composition of the electrolyte and temperature conditions copper plating.

Mechanical surface preparation

Before copper plating, scale, burrs and shells must be removed from the surface. The quality of processing is regulated by the provisions of the current GOST 9.301-86. Specific roughness parameters are set depending on the purpose of the coating. After machining parts from the surface, all defects that have a negative impact on the quality of copper plating must be removed. Technical lubricants and emulsions, metal chips, products of corrosion processes and dust are removed without fail.

Preparation for copper plating is carried out during the following technological operations:

1. Grinding. Upper layer parts are removed with abrasive elements, it can be thin, decorative or rough.
2. Polishing. During the operation, the smallest protrusions are smoothed out, the surface is shiny and mirror-like.
3. Brushing. Metal brushes are used to clean surfaces.
4. Tumbling. Details are rolled in special bells.
5. Chemical and electrochemical degreasing. For processing, organic and inorganic solutions are used.

The process of copper plating and the physical indicators of precipitation largely depend on the quality of the preliminary preparation of surfaces.

Copper is one of the ancient metals: people began to use it to create tools as early as the 4th millennium BC. Such a wide distribution of copper is explained by the fact that the substance occurs in nature in a metallic native state. And today copper is used everywhere - in metallurgy, the automotive industry, electrical engineering and construction.

Composition of copper

Metallic copper is a heavy metal of pink-red color, malleable and soft, which melts at a temperature of more than 1080 degrees Celsius, conducts heat and electric current very well: the electrical conductivity of copper is 1.7 times higher than that of aluminum and more than 6 times higher than iron, and only slightly inferior to the electrical conductivity of silver.

The specific features of copper are determined by the content of specific impurities in the metal, the amount of which can vary by approximately 10 - 50 times. According to the oxygen content, it is customary to use the following classification of copper:

• oxygen-free copper with an oxygen content of less than 0.001%;
• refined copper with an oxygen content of 0.001 to 0.01%, but with an increased presence of phosphorus;
• copper of high purity with an oxygen content of about 0.03-0.05%;
• general purpose metal with an oxygen content of 0.05 - 0.08%.

In copper, in addition to oxygen, hydrogen may be present, which enters the metal during electrolysis or during annealing in an atmosphere that contains water vapor. At high temperatures, water vapor decomposes to form hydrogen, which easily diffuses into copper.

Hydrogen atoms in oxygen-free copper are located in the interstices of the crystal lattice and do not particularly affect the properties of the metal. In oxygen-containing copper, hydrogen is able to interact at high temperatures with cuprous oxide, and water vapor is formed in the thickness of the copper, which is characterized by high pressure, which leads to swelling, cracks and ruptures. This phenomenon is called "hydrogen disease".

Iron, bismuth, antimony and lead degrade the ductility of copper. Impurities that are sparingly soluble in copper (lead, oxygen, sulfur, bismuth) provoke brittleness at high temperature, which makes the hot working process difficult.

Physical properties of copper

The main property of copper, determined by its use, is high electrical conductivity or low electrical resistivity. Such impurities as iron, phosphorus, arsenic, tin and antimony significantly impair its electrical conductivity. The magnitude of the electrical conductivity has big influence mechanical state of copper.

Second important property copper - significant thermal conductivity. Alloying additives and properties reduce the thermal conductivity of copper, therefore copper-based alloys of copper itself are significantly inferior in this indicator.

Copper at normal temperatures is corrosion resistant in environments such as fresh water, dry air, sea water at low water velocity, non-oxidizing acids and salt solutions in the absence of oxygen, dry halogen gases, alkaline solutions except ammonium and ammonia salts, organic acids , phenolic resins and alcohols.

In ammonia, ammonium chloride, oxidizing mineral acids and acid salt solutions, copper is not stable. Its corrosion properties also noticeably deteriorate in some environments with increasing amounts of impurities. Contact of copper with its alloys, with tin, lead in a humid atmosphere, sea and fresh water is allowed. At the same time, the contact of copper with zinc and aluminum is not allowed due to their rapid destruction.

Copper, its alloys and compounds are widely used in various industries. Copper in electrical engineering is used in its pure form in the production of contact and bare wire tires, cable products, power generators, telephone equipment and radio equipment. Vacuum apparatuses, heat exchangers and pipelines are made of copper.

Alloys of copper with various metals are used in the automotive industry and for the manufacture of chemical apparatus. Red copper wire for making all kinds of cords and bending the most complex elements. high properties copper make it indispensable in the production of filigree parts.

Copper plating procedure

Copper plating is a procedure for electroplating copper, the layer thickness of which is 1 - 300 microns or more. Copper plating is one of the critical processes in electroplating, which is used as a preliminary process in preparing a metal surface for coating with other metals - in chromium plating, nickel plating and silver plating, as well as a complete independent process.

The use of copper plating as a preparatory manipulation is due to the fact that this metal is able to adhere very firmly to steel, to even out surface defects. Other materials deposit well on copper, but not so much on clean steel.

Copper coatings are characterized by high adhesion to various metals, high electrical conductivity and ductility. They are usually applied to steel, zinc and aluminum parts.

The freshly applied copper coating has a bright pink matte or shiny color, depending on the application technology. Copper coatings in atmospheric conditions can easily oxidize and become coated with oxides, acquiring spots of various shades and iridescent stains.

Use of copper plating

For the most part, galvanic copper plating of metals is used in such cases:

1. For decorative purposes. Antique copper products are currently very popular. The copper plating procedure allows you to apply copper coatings to the metal, which, as it were, “age” after special processing and look like they were made a long time ago.
2. in electroplating. Electroplated copper plating of iron is used to create metal copies of products different shapes and various sizes. A plastic or wax base is created, which is coated with an electrically conductive varnish and a layer of copper. A similar copper plating technology is often used in the manufacture of jewelry, souvenirs, bas-reliefs, matrices and waveguides.
3. For technical purposes. Copper plating of metal is of great importance in the electrical field. Due to the low cost of copper plating compared to gold or silver coatings, copper coatings have found application in the manufacture of electrical busbars, electrodes, contacts and other elements that operate under voltage. Copper plating is often used as a solder coating.

Copper plating is used in combination with other electroplated coatings:

• When applying a multi-layer protective and decorative coating. As a rule, copper is used in combination with chromium and nickel (3-layer protective and decorative coating) and other metals as an intermediate layer to increase adhesion to the base metal and obtain a more durable and shiny coating.
• To protect the site during grouting. Copper plating of lead is able to protect sections of steel products from carburization - carburization. Only those areas that are subject to future cutting are covered with copper. The hard carburized surface layer is not amenable to such treatments, and copper can protect the coated areas from the process of carbon diffusion into them.
• When restoring and repairing parts. Copper plating of metal is an important procedure for restoration work and the restoration of chrome parts of motorcycle and automotive equipment. It is customary to apply a significant layer of copper - about 100-250 microns or more, which closes metal defects and pores and serves as a new basis for subsequent coatings.

Types of copper plating

The do-it-yourself copper plating procedure is available for even beginners to perform. To do this, you just need to know its basic subtleties. There are two ways of copper plating at home: with immersion in electrolyte and without immersion.

Immersed in electrolyte

The metal product is treated with sandpaper to remove the oxide film, rubbed with a brush, washed thoroughly with water, degreased in a hot soda solution and washed one more time. After that, it is customary to lower two copper plates, which are anodes, into a glass or a jar on copper wires.

A part is suspended on a wire between the plates. The wires coming from the copper plates are connected together and connected to the plus of the current source, and the part to the minus. After that, a rheostat is included in the circuit to adjust the current and a milliammeter. A direct current source is required, which has a voltage of no more than 6 V.

For copper plating at home, you need to prepare the following electrolyte solution. Take 20 grams of copper sulfate and 2-3 milliliters of sulfuric acid per 100 milliliters of water and pour into a bowl. Make sure that this solution completely covers the electrodes.

When using a rheostat, you need to set the current within 10 - 15 mA per square centimeter of the part surface. After about 20 minutes, you should turn off the current and remove the product, it has already been covered with a thin copper layer. The longer the process goes on, the thicker the copper layer will be.

Without immersion in electrolyte

This procedure is carried out for steel, aluminum and zinc. From one end stranded wire remove the insulation, then it is necessary to rake thin copper wires to obtain a copper brush. For the convenience of work, it is necessary to tie it to a copper brush or a wooden stick, and the other end of the cable must be connected to the plus of the current source.

Next, you should prepare an electrolyte - a solution of copper sulfate, preferably slightly acidified, and pour it into a wide bottle, into which it will be convenient to dip the brush. Prepare a metal plate or some other small object with a flat surface. It must be wiped with a fine sandpaper and degrease by boiling in a solution of washing soda.

Then you need to put the plate in a cuvette or bath and connect it with a wire to the minus of the current source. After the circuit is assembled, you only need to inject the electrolyte. Dip a “brush” into the copper sulphate solution, which should be drawn along the plate, do not touch the surface.

It is recommended to work in such a way that there is always an electrolyte layer between the brush and the plate. All the time the wiring must be moistened with a solution. The plate on the eyes will be covered with a layer of red metallic copper. It takes a few minutes to process a small part.

When you have applied the coating, you need to air dry the part and rub the matte copper layer to a shine with a cloth or woolen rag. The aluminum copper plating process, when the product is not lowered into the electrolytic bath, but is processed in small areas from the outside, adding electrolyte, is used in cases where the product is so large that it is impossible to find a suitable bath for it.

Baths of copper plating

Installations for copper plating from ordinary galvanic baths are no different. Electrolytes for copper plating are fairly easy to obtain if you have the right ingredients on hand. There are two types of copper solutions: alkaline and acidic.

In acidic solutions, you will not be able to get well-adhered copper coatings on zinc and steel products, because zinc and iron in this case dissolve with copper, and the adhesion to the protective coating is broken.

To eliminate this feature, it is recommended to create the first thin copper layer (2–3 μm) in an alkaline solution for copper plating, and in the future to increase the coating to a given thickness in an acidic electrolyte, which is more economical. Zinc products that have a complex shape are best copper-plated in alkaline electrolytes.

The most common acidic electrolytes are hydroboric and sulphate. Sulfuric acid electrolytes, which are characterized by simplicity of composition, high current efficiency and significant stability, have found the greatest use.

Before copper plating of steel parts in acidic electrolytes, it is recommended to pre-copper them in cyanide electrolyte or to deposit a thin sublayer of nickel. These electrolytes have several disadvantages.

One of them is the impossibility of direct coating of zinc and steel parts due to the contact precipitation of copper, which has poor adhesion to the base metal. Also, electrolytes have an insignificant scattering power and a coarser structure of deposits compared to other electrolytes.

Among the alkaline electrolytes of copper plating, pyrophosphate and cyanide electrolytes are known.
Cyanic electrolytes from copper are characterized by high scattering abilities, the possibility of copper plating of joinery and fine-grained structure of deposits.

The disadvantages of alkaline electrolytes include low current density and instability of the solution due to carbonization under the action of carbon dioxide of free cyanide. In addition, cyanide electrolytes are distinguished by a reduced current efficiency - no more than 60-70%.

Thus, copper is a metal that is used everywhere: in the automotive industry, electrical engineering and construction. And in electroforming, copper plating technology is known for preparing a metal surface for coating with other metals or as an independent process.