Copper plating of steel with copper sulfate with current

Copper plating at home

The content of the article:

Copper plating at home is a technological process that allows you to apply a layer of copper with a thickness of 1 to 300 microns to metal, as well as other materials (tungsten, steel). Coating with a copper layer ensures good adhesion of the metal and, with increasing thickness of the coatings, gives shine to products, eliminates minor defects, and allows you to create copies of things. Surprisingly, you can do all this yourself. Today we will tell you how to carry out copper plating of metal at home.

What is it for?

Electroplating technology involves creating a solution and forming various electrodes. During this process, copper ions, which are dissolved in the electrolyte, are attracted by the negative pole of the workpiece to their surface point.

Electroplating of metal parts in industry is used not only as a final processing process. It can be used to prepare parts for subsequent operations (for example, chrome plating, nickel plating, silver plating of any objects).

Chemical copper plating of parts is most often carried out at home. It is also worth noting that there are many ways to carry out such a procedure, each of which has its own advantages and disadvantages.

Electroplating with copper at home: general information

From a technical point of view, processing is an electrochemical process. There are always two “participants” in the process: the anode + electrolyte (metal source) and the part.

The technology of copper electroplating at home is quite simple. It consists in the fact that due to the electrolyte and the current conducted through it, metal atoms are released. They settle on the surface, forming a copper coating.

Among the main stages of electroplating copper plating at home:

Surface preparation (mechanical and chemical).
Applying an undercoat (if necessary)
Copper plating in an electrolyte corresponding to the original metal.

For decorative galvanic copper plating, matte and shiny copper plating electrolytes are suitable. After applying the layer, you can treat the surface in electrolytes of silver, gold, nickel, etc.

Process concept

Copper plating is a procedure in which a small layer of copper is applied to the surface of an object. Typically, a galvanic method is used, which involves the transfer of copper ions from a positive to a negative source to the surfaces being treated. As a rule, copper plating is carried out for the subsequent application of nickel or chromium, but often this procedure becomes an independent technological operation for the final finishing. This is an actively used electroforming process that requires the creation of a copper coating.

Necessary tools for copper plating at home

“Ingredients” without which copper plating will not take place, but which can actually be prepared at home. Our galvanists claim that, first of all, we need:

DC source. Selected depending on the size of the product.
Anodes. Anode plates perform several functions. First of all, they supply current to the electrolyte, and secondly, they compensate for the loss of metal that goes into coating the product.
Working electrolyte. Acidic, alkaline or pyrophosphoric solution. The composition of the electrolyte is selected depending on the starting metal. It must be remembered that any electrolyte is not universal and is not suitable for all jobs.

Necessary equipment

Copper plating can be applied at home using even the most ordinary equipment. Installation of a bathtub for the procedure under consideration is carried out in approximately the same way as galvanic ones. It is worth considering that there are two types of active solutions: acidic and alkaline.

When working it can be used:

Small copper plates as electrodes.
Wire for supplying current.
A current source, for example, a battery, which is designed to supply a current of 6 V.
A rheostat can be installed to regulate the current.

Copper plating of aluminum and other alloys at home does not require much time. Various fabrics can be used to clean the resulting surface.

If you find an error, please select a piece of text and press Ctrl+Enter.

Preparation of material

How to properly prepare a simple copper plating electrolyte

It is worth noting that electroplating with copper at home is difficult because the chemicals are not easy to find. Companies selling such products do not sell them without special documents. But you can do everything yourself.

It is possible to prepare electrolyte at home only if the recipe is strictly followed. The simplest electrolyte contains:

Distilled water (or bidistillate).
Copper sulfate.
Hydrochloric or other acid.

The finished solution has a bright blue color and no odor. Some sediment may be present. It is important to follow all safety precautions with chemical reagents, especially at home: protect your hands and eyes first. Clothes on which the solution could accidentally spill are best classified as summer clothes.

It is better to store such liquid in glass bottles or plastic canisters, and be sure to indicate the date of bottling and the name of the solution. Proper storage of components will save you from possible problems. Electrolyte preparation should take place in clean plastic or glass containers.

Preparing material for copper plating at home

Chemical copper plating is an alternative to the electrochemical method, but cannot always replace it. In this process, it is important to carefully prepare the part, completely eliminating scratches, dirt, chips, etc. In order to degrease an item, you can use both pure solvents and degreasing solutions.

However, there is no universal method - different types of metal are cleaned in different ways:

Steel. You can degrease steel with a solution containing caustic sodium and caustic potassium at 70-90 degrees Celsius. This will take about 20-30 minutes. Be careful and use a hood.

Copper and alloys. Degreasing is carried out with sodium hydroxide, preheated to 40°, for about 10 minutes.

Cast iron. The degreasing process requires a solution containing sodium hydroxide, liquid glass, sodium carbonate and sodium phosphate when heated to 90°.

Tungsten. Copper plating of tungsten at home begins with cleaning the object from dirt and other defects with sandpaper.

Electroplating with electrolyte solution

In this way, you can coat steel with copper at home, as well as other parts except aluminum and zinc.

For the further procedure, it is necessary to prepare the following materials:

Small plates of copper.
Conductive wire (it’s better to stock up on a few meters).
A current source whose voltage should not be more than 6 V.
Rheostat to regulate current.
Ammeter.
Electrolyte.

Important! The last component can be purchased at a special store, or you can make it yourself. To do this, you need to make a solution of sulfuric acid and distilled water at a ratio of 2/100 ml. The desired solution will be obtained when you add no more than 20 g of copper sulfate to the composition.

The essence of the work is as follows:

Clean the workpiece with sandpaper - this is necessary in order to remove the oxide film. Further, covering metal with copper at home will not be so difficult.
Degrease a metal object with a hot soda solution and rinse it with clean water.
Pour the prepared electrolyte into a glass container of suitable volume.
Dip two copper plates on prepared conductive wires into the liquid. Between two copper plates, a degreased part is suspended on the same wiring.

Important! Make sure that the copper plates are completely immersed in the electrolyte.

Next, the ends of the wires from the copper plates are connected to the positive terminal of the current source, and the part is connected to the negative terminal. Next, you need to connect an ammeter with a rheostat to the created electrical network. After the current is connected to the circuit, the rheostat needs to be set to approximately 15 mA per 1 cm of the detailed surface area.
Next, the part is kept for about 15-20 minutes.
After the time has passed, you need to turn off the power supply and remove the metal being processed from the solution.

Ultimately, you will notice that you were able to copper plate metal at home, because it will be completely covered with a thin, shiny film.

Important! The thickness of the copper layer will depend on how long the part was kept in the electrolyte.

Safety precautions for copper plating at home

Despite the possibility of electroplating at home (copper plating), the process remains dangerous. Any galvanic process involves toxic substances that can become very hot. Therefore, precautions must be strictly observed.

The first rule of copper electroplating at home is to work only in a non-residential, well-ventilated area. Places such as a workshop or garage are suitable. The second rule is that the equipment used must be grounded. Third is personal safety.

To ensure your own protection when copper plating at home you need:

Wear a respirator at all times to protect your airways. It is best to use a hood.
Protect your hands with durable rubberized gloves.
Wear a special uniform or oilcloth apron and anti-burn shoes.
Don't forget glasses for visual safety.
Do not bring food or drink into the premises.

Electroplating at home: copper plating

Why is copper so popular in electroplating? It has high adhesion (in other words, grip) to a wide variety of materials. This means that it adheres perfectly to products made of steel and tungsten, without flying off or chipping.

Copper is a beautiful bright metal that looks like pink-red nuggets. The material conducts not only heat, but also electric current - hence the high demand in the field of electrical engineering and instrument making. However, pure copper is difficult to find. More often it comes with various impurities.

They are characterized by low resistance, which is used in electrical engineering
Hides minor surface imperfections.
It oxidizes quickly, which is used to obtain an “antique” effect.

There are two copper plating technologies. One occurs by immersing the product in an electrolyte solution (with or without current supply). The second method is a method of selective coating without immersion in a solution. Let's look at both.

Immersion method

At home, the surface to be electroplated should be carefully treated. For example, sandpaper and a brush. Afterwards, be sure to degrease the part and rinse it.

The anode plate (two are possible) is placed in a container, which we will call a bath. The positive terminal is connected to the anodes.
A part is suspended between the anodes on any convenient conductor, and the negative pole from the power supply is connected to it.
The finished solution is poured into the bath - in this case, the coating level should be higher than the part is located.
After connecting the electrodes to the current source, the operating current is set. This is approximately 1 A/sq.dm. coverings.

The duration of work depends on the required layer thickness, usually from 5 minutes.

Non-immersion coating

This method of copper plating has limitations - most often it is suitable for surface restoration. This method can only apply a small thickness of metal. There is no point in coating products using this method that can be copper plated in a bath. Procedure for galvanic copper plating at home:

A “tampon” is prepared for applying the coating. Take a copper conductor and wrap a piece of artificial fabric (polyester is fine).
The opposite end of the conductor is connected to the positive terminal of the voltage source.
Fill the container with an electrolyte solution - this makes it easier to dip the pencil.
The part is carefully cleaned and degreased, and then placed in an empty bath. There the product is connected to the negative terminal.
The swab is moistened in the solution. Then it is passed over the surface of the product, painting it gradually.

The process lasts until the product is completely covered with a copper layer.

Physical and mechanical characteristics of copper and areas of use of copper plating

Copper density is 8.96 g/cm 3, atomic mass 693.54, electrical resistivity 1.68×10 -8 Ohm×m, melting point +1083°C. In the open air, in the presence of aggressive chemical compounds, copper oxidizes, and 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 becomes green; the top layer consists of hydrocarbonates. Copper easily dissolves in a solution of nitric acid; diluted sulfuric acid has almost no negative effect on chemical copper plating. But the presence of oxygen increases the rate of chemical reactions. If there are open pores in the coating, a galvanic couple is formed, which must be taken into account when plating copper. In this case, iron is the anode, and corrosion processes occur very intensively.

Due to 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 to various metals: aluminum, silver, zinc, nickel, lead, chromium, etc. Due to these features, chemical copper plating is often used to create a sublayer for silvering, nickel plating, and chrome plating of surfaces of parts. Copper plating has become widespread as a method of effectively protecting individual parts of parts from the appearance of the carburizing effect during the carburizing process. Depending on the purpose of parts or products, electroplated copper can have the following thickness:

Thickness of the copper layer on the surface of the workpieces

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, fluoroborate, silicofluoride, sulfate, chloride and sulfamide solutions are used.
Complex electrolyte. Primarily alkaline, copper is present as positively or negatively charged complex ions.

Graph of polarization curves of copper deposition from various types of electrolytes

The deposition process in acidic electrolytes occurs at high current densities; they are stable and simple in chemical composition. The main components are the corresponding acids and salts; the copper deposits from them are quite dense and have a coarse-crystalline 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 using complex ions; they require high cathodic polarization. The current output is lower, which contributes to more uniform deposition; the structure is fine-crystalline. Pyrophosphate, cyanide, ammonium, tripolyphosphate, citrate and other solutions are used.

Electrolyte Dissipation Capacity for Copper Plating

Simple acidic compounds

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

Effect of sulfuric acid content on the electrical conductivity of the electrolyte

When stirring, the concentration of copper ions on the cathode layer increases. As the temperature rises, the solubility of copper sulfate increases, the electrolyte increases acidity, which leads to the formation of fine-crystalline precipitates.

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

Modes and composition of sulfate electrolytes for copper plating

To form a shiny coating, AMF anodes are used, which do not allow the formation of sludge, or anodes made of especially pure refined copper.

Effect of copper concentration on current density with stirring (1) and without stirring (2). 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.

Fluoroborate. They are highly resistant, the electroplating is dense and fine-crystalline, and the dissipation properties are the same as with copper sulfate plating. Due to the high solubility, the current density increases; it is impossible to deposit copper directly on the part.

Composition and operating mode of fluoroborate electrolytes

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. To improve the quality of copper plating, sodium carbonate is used, and copper sulfate is used to reduce it.

Nitrate. The electrolyte is used in electroplating and provides improved quality of the deposit.

Regimes and composition of nitrate electrolytes

Cyanide. The processing conditions differ significantly from acid precipitation; in them, copper exists in the form of complex ions, which significantly reduces its activity. An increase in current density forces the cathode potential to sharply shift into a field of negative values. But the copper plating process cannot be carried out at increased current density due to the fact that the copper yield may 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.

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

Read also: Molds for casting lead weights

Mode and composition of pyrophosphate electrolytes

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

Mode and composition of ethylenediamine electrolytes

Loading and unloading of parts should be carried out at a minimum current strength; in the first 40–50 seconds, a current impulse is given, three times higher than the operating values of copper plating.

Polyethylenepolyamine. During the processing of parts, the potentials shift to a field of negative values, and an electrolyte is used instead of cyanide.

Operating mode and compositions of polyethylene-polyamine electrolytes

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. The sediments are uniform in thickness, dense and semi-shiny.

Operating modes and composition of ammonium electrolyte

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

Bath without a pocket. The simplest design, used both individually and on production lines.

Bath without pocket

Bathtub with pocket. Treatment can be carried out with simultaneous processes of removing the upper contaminated electrolyte layer.

Bathtub with pocket

The specific choice of a copper plating bath is made depending on the characteristics of the enterprise, the characteristics of the parts to be copper plated and the overall production capacity.

During 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 water fittings are installed on copper plating baths. Due to special mechanisms, the quality of the copper plating process is improved. The plastics used are adapted to the chemical composition of the electrolyte and the temperature conditions of 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 the parts, all defects that have a negative impact on the quality of copper plating must be removed from the surface. Technical grease and emulsion, metal shavings, products of corrosion processes and dust must be removed.

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

Grinding. The top layer of parts is removed with abrasive elements; it can be thin, decorative or rough.
Polishing. During the operation, the smallest protrusions are smoothed out, the surface is shiny and mirror-like.
Brushing. Metal brushes are used to clean surfaces.
Tumbling. The parts are rolled in special bells.
Chemical and electrochemical degreasing. Organic and inorganic solutions are used for processing.

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

In the modern world, copper alloy has become more widespread. It is applied to the surface to give visual appeal to various products. Copper plating at home is often carried out to significantly increase electrical conductivity. In some cases, the process in question is an intermediate operation that allows another substance to be applied to the surface.

Features of galvanoplasty at home

Electroplating is the process of depositing copper onto a conductive or non-conductive surface of a product and then removing the coating from the negative matrix. This way you can get many very accurate copies from one product. At the same time, there is a condition: build up copper with a thickness of at least 200 microns so that the product turns out durable.

It is important to consider that if the surface of the product does not have conductor properties, then more effort will be required - namely, a special preliminary coating with graphite, silver or copper. Copper is considered the main metal for electroplating, but matrices can be grown from silver with a purity of 9999.

Electroplating training

We can conclude that copper plating today is one of the most relevant electroplating processes that anyone can learn. conducts training in the field of "Galvanics" for everyone! You will be able to choose a training program that is convenient for you, which is best suited for electroplating at home and beyond. All questions you may have can be asked by phone or email; our technologists will advise you on training courses.

Video guide to copper plating parts at home:

Source of the article: https://6mkm.ru/nashi-tehnologii/mednenie/mednenie-v-domashnih-usloviyah/

Plating metals with copper at home

Copper plating at home: coating features, technology, electrolytes and equipment. Galvanic copper plating with and without immersion. Homemade electrolyte recipes. Safety precautions and disposal of chemicals.

When copper plating at home, accessible and inexpensive materials are used that are easy to purchase in retail stores.

Copper sulfate is used to control mold, mildew and garden pests and is freely available in hardware stores, and short lengths of copper pipes or electrical bars can be used as anodes.

Types of copper plating

The procedure in question can be performed even by beginners in the field of metallurgy. To obtain a high-quality surface, you need to know all the features of the process. Copper plating of lead and other metals at home can be carried out using two different technologies:

Immersed in electrolyte. This technology involves dipping the workpiece into a prepared solution, after which voltage is applied. It is often used when the workpiece is small in size, since a smaller amount of special electrolyte is required. To immerse the workpiece, a bath or other container is required that does not react to the effects of the solution used.
Without immersion in a pre-prepared container. It is difficult to implement, but also allows you to achieve high quality copper surface film.

In both cases, a supply of electricity is provided, due to which the substance is activated.

The most suitable processing method is selected depending on the result to be achieved. Let's take an example:

Obtaining a protective and decorative layer. In this case, chromium is often mixed with nickel and copper. Due to this combination of alloys, a reliable surface can be obtained.
To protect the surface during cementing. Applying a thin layer of copper helps protect the workpiece from cementation. The surface that will be subsequently processed by cutting is covered with the solution.
Restoration and repair of parts. When restoring chrome parts of cars and motorcycles, the technology in question can be used. When applying a layer of no more than 250 microns, surface defects in the metal can be hidden.

Both processing technologies have their own specific characteristics that must be taken into account.

Copper plating in solution with electrolyte

Electroplating with copper at home with immersion is carried out extremely often. This technology allows you to obtain a uniform coating. The features of this processing method include the following points:

To remove the oxide film before copper plating, the workpiece is treated with sandpaper. After this, the product is washed and degreased with a hot soda mixture. If you do not pay attention to the preparatory stage, the process being carried out will not allow you to obtain a product that is resistant to mechanical stress. Metal that is susceptible to corrosion must be well cleaned, since even small chips can make the surface uneven.
Two plates of the same alloy are lowered into a jar or other container on copper wires. They act as an anode. The container used must be made of glass.
The workpiece is suspended between two anodes, which is connected to the minus, and the plates to the plus. A battery producing a voltage of 6V can be used as a power source.
Galvanic copper plating involves the use of a specific solution. It is the connecting element between the part and the anodes. A solution for galvanic copper plating can be prepared by taking 20 grams of copper sulfate and 3 milliliters of sulfuric acid. To dilute and mix these ingredients, you can use 100 milliliters of distilled water. When working with the resulting solution, you must be extremely careful, since burns may occur if the substance comes into contact with exposed skin.
Copper plating of aluminum with copper sulfate at home can only be carried out if the electrodes are completely covered with the solution. If they are kept dry, they may heat up and melt. During prolonged processing, the substance may heat up and its volume will decrease.

Galvanic copper plating

When using the technology in question, the current is set at 15 mA per square centimeter. It usually takes at least 20 minutes to cover the entire surface with a special alloy. As the period increases, the coating becomes thicker.

Copper plating without immersion in solution

A similar method is used to coat steel, zinc or aluminum. Coating a product with copper at home in this case is carried out with a wire, from which the insulation is first removed to obtain a kind of brush. The opposite end of the wire is connected to the positive energy source. Chemical copper plating at home also involves the use of a special solution, which increases the efficiency of the process.

Among the features of creating the required solution, the following points can be noted:

A solution of copper sulfate is used. It can be purchased in specialized stores. In addition, a special electrolyte is made by mixing various chemical elements.
The composition is slightly acidified. Due to this, the efficiency of the procedure is significantly increased.

The substance is applied to the surface, after which the metal surface is prepared. It is cleaned of contaminants and then degreased. After this, the plate prepared in advance is placed in the bath and a minus voltage from the current source is supplied to it.

Copper plating of aluminum

This process requires that there is always a layer of electrolyte between the assembled wires and the plate. This ensures a high degree of conductivity. It only takes a few seconds to coat a small product.

After coating, the product is air dried. Various pollutants must not be allowed to enter. The next step is to rub the copper layer with a woolen rag or other cloth. In most cases, the technology in question is used when the product is large and cannot be immersed in a bathtub.

The purpose of copper plating of metals and their scope of application

Copper has a set of properties that determine the conditions for its use in copper plating of metals and non-metallic materials. It is plastic, easy to polish, and the galvanic layer after copper plating has virtually no pores.

For this reason, copper coatings are very often used as a sublayer for chrome and nickel plating of products that are operated under conditions of constant compression and tension. The ductility of copper is an ideal condition for its use in electroforming.

Thick-layer copper plating of artistic products and complex models allows you to create their absolutely exact copies that do not crack or deform when removed from the original.

Copper has the best electrical conductivity among base metals and is easily soldered. Therefore, copper plating of steel products is widely used in radio engineering and electrical engineering in the manufacture of conductors, contacts, antenna parts and waveguides.

When high-frequency signals are used, the copper coating experiences a high current density (skin effect), which reduces the overall resistance of the conductor.

Another area of use of copper plating is the creation of thin conductors on the surfaces of plastic products, as well as the coating of plastic with conductive layers.

Where is it used?

There are several main cases of using copper plating:

For decoration. Recently, the demand for antique copper products has increased. Using a special treatment, the applied layer of copper gives the surface an “aged look”.
Galvanic copper plating. This method of applying iron is used to produce copies of individual copper parts of various shapes and sizes. First, a base of wax or plastic is created, which is subsequently coated with an electrically conductive solution and a copper layer. This technology is widely used in the manufacture of souvenirs, jewelry, as well as bas-reliefs and waveguides.
In electrical engineering. The low cost of copper plating makes this method stand out - in comparison with coatings made of silver or gold, copper products can be used in the electrical industries (for the production of electrodes, live contacts and as a base for soldering).

Copper plating technology is also combined with various types of galvanization:

To create a multi-layer decorative coating with weak protective characteristics. In this case, copper, chromium and nickel are used - a three-layer protective and decorative layer, which increases the degree of adhesion to the main surface material.
To protect a specific area of a part during carburizing. When galvanizing lead products with copper, it is necessary to protect the coatings of steel elements from carburization. Only those areas that will be subsequently subjected to mechanical processing can be copper plating.
During restoration work. During the copper plating process, an intermediate layer is formed on the restored part, which will subsequently serve as the basis for a more durable coating (chrome plating, nickel plating). The galvanic method is characterized by the application of a thick layer of copper, up to two hundred and fifty micrometers. This is due to the need to eliminate all damage and surface defects.

On video: galvanic copper plating for decorative purposes.

Characteristics of copper-plated metals

Under the influence of atmospheric factors, it quickly deteriorates, and even at home it is usually coated with varnish. At the same time, the copper sublayer significantly improves the characteristics of multilayer coatings in terms of mechanical strength and corrosion resistance.

Stainless steels are typically protected from corrosion by a three-layer coating of chromium, nickel and copper. In this case, copper plating is carried out first in order to ensure the ductility of the entire composite layer when using the product under conditions of variable loads.

Copper plating plays exactly the same role in coatings of rolled metal and sheet iron, from which profile products are made that are used in marine climates and aggressive environments. Copper-plated wires and aluminum contacts are easy to solder and have lower resistance, especially at high frequencies.

The technical conditions of electrolysis make it possible, when copper plating metals for decorative purposes, to paint the surface layers of copper in various colors and give them additional shine (in the photo below - copper plating on stainless steel).

What is copper plating?

Copper plating is usually understood as the electroplating of copper, and the layer thickness should range from one to three hundred micrometers. Copper plating is the coating of copper on a metal product in preparation for chrome plating, nickel or silver plating. However, this procedure can also be used as an independent surface treatment.

As a preparatory process, copper plating of steel helps to level the surface, because, as you know, copper adheres firmly to steel, which cannot be said about other materials. Various metals are deposited quite well on a copper-plated coating (much better than on pure steel).

Experts include high adhesion to other metals, ductility and reliability among the distinctive characteristics of copper coating. However, with constant exposure to environmental factors, the copper coating quickly oxidizes and becomes covered with rainbow stains, spots and plaque.

Copper plating can be done on surfaces made of steel, zinc and even aluminum. The newly applied copper layer has a crimson tint with a slightly noticeable metallic sheen.

Copper plating process technology

In general, the galvanic copper plating process consists of the following stages, which, depending on the technical conditions, can be supplemented with other types of processing:

mechanical cleaning (using a wire brush, sandpaper and power tools);
washing with running water;
degreasing (chemical or electrolytic);
washing and drying;
checking the quality of surfaces;
immersing the product in electrolyte;
current supply and process control;
washing and drying the finished product.

The basis for the vast majority of electrolytes is a solution of copper sulfate (copper sulfate), to which various chemical reagents are added, depending on the processing conditions.

Galvanic copper plating technology is based on the use of sacrificial anodes, which serve as a source of copper anions, deposited in the form of a thin layer on the surface of the cathode-product. Copper plates of any purity act as cathodes.

Methods of copper plating of metals

Using the chemical method it is impossible to obtain coatings of great thickness, but it is simpler, cheaper and can be performed under extremely simple conditions. Using it, it is easy to obtain thin decorative films not only on metals, but also on plastic, glass, ceramics, etc.

For example, chemical copper plating of steel occurs in a few tens of seconds by simply immersing it in copper sulfate.

Immersion in electrolyte solution

Both methods can be used with complete immersion of the part in an electrolyte solution. With the galvanic method, copper anions are separated from the anode and move to the cathode under the influence of electric current, and with the chemical method, their movement occurs due to the different electronegativity of the metals.

Therefore, in the first case, other things being equal, a much larger amount of copper is deposited in the same unit of time, but electrical energy is expended.

It is recommended to carry out copper plating of aluminum only by immersion, which must be performed immediately after degreasing and etching in acid, otherwise a strong oxide film will quickly form on its surface.

Chemical basis of the process

Copper plating of metals is performed using two basic methods. Galvanic copper plating is performed using electric current, while chemical copper plating does not require electricity. Both methods require the use of an electrolyte based on copper sulfate. During chemical copper plating, a catalytic mechanism is activated, which accelerates the chemical reaction of copper deposition on the surface of another metal. But with the chemical method, the covering layer of copper is thin, but the coating procedure is quite simple and cheap. With the chemical copper plating method, the movement of copper anions occurs due to the different electronegativity of the metals. The formula of the complex coating anion looks like this: anion [CuC4H4O6(OH)2] 2-.

External electrical energy is not spent on this process, so the coating layer is thin. But this method can create thin decorative films not only on metals, but also on other materials - plastic, glass, plant leaves and even insects.

Electroplating with copper at home

At home, galvanic copper plating is most often used for decorative and applied purposes or for applying a copper sublayer before nickel and chrome plating.

Copper is usually used to cover furniture fittings, kitchen utensils, lamp elements, jewelry, as well as parts of tools and knives. The selection of galvanization parameters by home craftsmen is usually done experimentally based on the color and quality of the coating.

Those who are seriously involved in copper plating, including for commercial purposes, use adjustable current sources or rheostats in their installations, with the help of which the required current density and deposition rate are set.

For those who do not want to bother with the independent selection of chemical components, online stores offer kits for preparing a variety of electrolytic solutions, including those for copper plating of plastics and organic materials.

And one of the most popular trends in modern home electroplating is copper coating of dried plants, nuts, acorns and insects. Such products look impressive and are used not only for decorative purposes, but also for making jewelry (see copper plating and patination of walnut below).

Safety precautions

Therefore, at home, all work on the preparation of electrolyte and chemical processing of the product must be performed with rubber gloves and an oilcloth apron, and for large volumes, use respirators and safety glasses.

Copper sulfate itself does not require any treatment before disposal, but since its electrolytes contain sulfuric acid, it must be neutralized with alkali or soda.

Equipment and materials

Copper plating at home requires a minimum set of equipment and reagents. Any plastic or glass container can be used as a galvanic bath.

To prepare an electrolyte for copper plating, you only need copper sulfate and clean water, and the current source can be an old phone charger or a couple of batteries. Other materials and tools are also few and available at home.

First of all, this is sulfuric acid (battery fluid), soda, scraps of copper products (pipes, bars, contacts) and cloth-based sandpaper.

Equipment and materials

To carry out the process of chemical copper plating, you can use many different solutions, but in each specific case a minimum set of equipment and reagents will be required. Any plastic or glass container can serve as a galvanic bath. The electrolyte is prepared from pure water and copper sulfate. You will also need sulfuric acid (battery fluid), soda, scraps of copper products (pipes, bars, contacts) and cloth-based emery cloth.

The chemical copper plating solution contains divalent copper salt (copper sulfate), a complexing agent, a reducing agent (formalin), accelerating and stabilizing additives, and sodium hydroxide to regulate pH. The rate of copper plating increases with increasing temperature and with the introduction of certain additives (sodium carbonate, pyridine).