What is galvanized metal

Methods and features of electroplating

The technology of applying other materials to the metal surface is considered popular in the manufacture of various products. The protective layer reduces the risk of rust and increases strength. Galvanic coating is a protective layer that protects the surface of a part from corrosion. After processing, the service life of the product increases and technical characteristics are improved.

Parts with galvanic coating (Instagram / mazakovvitalii)

Description of the method

Galvanization is a technological process in which a layer of another metal is applied to the surface of a metal workpiece to protect the part. The film prevents the formation of rust and extends the service life of the product. Copper, nickel, zinc, and chromium are often used for the procedure.

Galvanization not only protects metal products from corrosion, but also improves its technical characteristics and appearance. To “refresh” an object, a galvanic coating of gold or silver can be applied.

A little history

Electroplating of metal was first developed by scientist Luigi Galvani. He came up with a method of depositing metal particles onto the surface of another metal. Luigi described only the theoretical part of the process and did not delve into its practical application.

Moritz Hermann collected the data together and conducted the first practical experiments. Having moved to Russia, he changed his first and last name, becoming Boris Jacobi. He tried out a galvanic bath for the first time and conducted a test using a copper solution. In 1840, his work was published describing the finished technology.

Process Features

Galvanic treatment consists of several steps:

1. Preparation of electrolytic solution. Its composition will depend on the required technical characteristics of the finished film.
2. Immersion of 2 anodes in the prepared solution. The positive contacts are connected to them. The voltage is transmitted by a direct current source.
3. Slowly immerse the workpiece in the electrolyte. It must be connected to the negative contact. The workpiece will act as a cathode.

As a result, the electrical circuit will be closed and the galvanization process will begin. Metal particles contained in the electrolytic solution and having a positive charge will be deposited on the workpiece.

Source: https://metalloy.ru/obrabotka/galvanicheskoe-pokrytie

Metal galvanization

Coating the surfaces of finished products with an additional layer allows you to solve many technical and aesthetic problems. One of the most common methods of applying such coatings is metal galvanization.

This method belongs to the category of electrochemical processes occurring in a container filled with an electrolyte. Electroplating forms a new layer due to the penetration (diffusion) of molecules into the surface layer of the workpiece, forming a thin film.

As a result of this process, a layer with new physical and mechanical properties is obtained.

Equipment and materials

The following equipment is used to carry out work related to galvanic coating:

• galvanic baths made of material resistant to electrolytes;
• heating devices;
• source of direct electric current;
• system for fastening electrodes: anode and cathode (taking into account the fact that the cathode is the workpiece);
• equipment for preliminary preparation of parts.

The assembled installation can be used both in industrial conditions and in a home workshop. To carry out electroplating in a home laboratory or workshop, it is necessary to accurately calculate the expected consumption of the necessary materials and the time the part will remain in the electrolyte solution.

As consumables, galvanization requires the selection of appropriate electrolyte and anodes. They are used depending on the method of processing the part. Currently, a large number of electrolytes have been developed for galvanic processing.

For example, sodium or potassium cyanide, sodium or potassium carbonate solution, hyposulfite. The use of various metals or mixtures in a salt solution allows you to select the necessary properties of the surface layer of the workpiece. In addition to liquid solutions, cold suspensions are used.

It is used to carry out the cold galvanizing process. It is directly applied to the surface of the part.

Source: https://stankiexpert.ru/tehnologii/galvanizaciya-metalla.html

What is galvanized metal?

• Coating method
• Coating process
• Types of coatings:

• Copper plating
• Gold plating
• Chrome plating
• Silver plating
• Nickel plating
• Zinc coating
• Tin plating

• Designation of galvanic coatings

In the modern world, the procedure of applying various substances to metal materials that prevent the formation of a corrosive coating on them has become very popular. Galvanization serves to protect metals from the formation of rust and to extend the service life of a product.

Electroplating method

In the modern world, the galvanic method is often used when processing metal surfaces. Electroplating of materials involves applying a thin metal layer to their surface. In this case, a film of small thickness is formed, which resists the oxidation of individual metals. The galvanic method is used to give a product or material:

• strength,
• wear resistance,
• resistance to corrosion,
• attractive external qualities.

In the modern world, this method of processing metal coatings has become very popular because a large number of requirements are placed on equipment and other products.

It is required to constantly increase the strength of individual parts and increase their resistance to the influence of an aggressive external environment. Metal parts in modern production must be able to withstand temperature changes.

This is the reason why many industries widely use the galvanic method of processing metal products.

Important: The thickness of the galvanic coating is quite thin with the electroplating method. It ranges from 6 to 20 microns. It depends on the materials that are used for the electroplating process.

Due to their durability, galvanic coatings are widely used in such industrial sectors as:

• aircraft manufacturing,
• mechanical engineering,
• construction industry,
• radio engineering industry,
• electronics industry.

Electroplating Process

Electroplating first appeared in 1836. It was discovered by the Russian physicist Jacobi. He conducted a series of experiments and found out that after passing metals through aqueous and salt solutions under the influence of electric current, positively charged ions settle on the cathode.

When passing through salt solutions with the help of an electric current, metals disintegrate into ions that have different charges. Those that have a negative charge are deposited on the anode. Those that have a positive charge are deposited on the cathode.

Its role in galvanizing is played by metals that need to be protected from corrosion.

The electroplating process is quite simple from a physical point of view.

It consists of three main stages:

• Surface preparation. At this stage, it is necessary to carefully prepare the metal surface for the galvanizing procedure. To do this, you first need to remove all dirt from it and carry out the degreasing process. Then it is necessary to rinse the surface with water and treat it with means to stop the oxidation process.
• Electroplating. After all the preparatory procedures, the process of immersing metal parts in galvanic baths begins. They contain a metal alloy that will cover the surface. The entire procedure is carried out at high temperatures. In this case, the magnitude of the electric current is maintained at a certain level.
• Processing of metal-coated material. At the final stage, tests are carried out to determine the level of adhesion of the metal alloy to the surface.

Types of galvanic coatings

In the modern world, various metals can be used for electroplating. They provide a thin film that provides reliable protection.

Today they highlight:

Copper electroplating

This procedure is called mediation. Thanks to copper, it is possible to create a durable protective film on the surface of a wide variety of metals. Most often, copper sulfate is used for this procedure.

Gold electroplating

Currently, the gilding procedure has become widespread. It consists of covering a metal surface with a solution to give it a more expensive appearance and to protect it from corrosion.

Electroplated chrome coating

Treating metals with chromium makes them stronger and more resistant to the conditions offered by aggressive external environments. Thanks to this element, a thin film is formed on the surface, which has protective and aesthetic qualities.

Silver plated

Silver plating is often used in industrial settings. At the same time, a silvery film appears on the surface of the metals, which gives the metals a considerable number of useful characteristics. In addition, silver-plated products always look expensive.

Nickel electroplating

Coating with this element is economical. The use of this method of metal processing is optimal for making the metal material resistant to external environmental influences.

Electroplated zinc coating

This procedure is called galvanizing. Thanks to it, a thin film of zinc is formed on the surface of metals, which prevents the formation of rust. In addition, this coating adds shine to the products.

Tin electroplating

Tin is used for coating metals such as aluminum, zinc, steel and copper. It gives them strength and hardness.

Galvanic coatings GOST

Source: https://morflot.su/galvanizirovannyj-metall-chto-jeto/

Electroplating

Electroplating is one of the most common methods of protecting metals from corrosion. The quality of galvanic coating greatly affects the quality of finished products, their durability and performance characteristics.

Galvanic coatings have found wide application in many sectors of the national economy, not only as a good means of protecting metals from corrosion. A galvanically deposited layer of metal can significantly increase the wear resistance of the main product, its electrical conductivity and many other important indicators.

Electroplating is produced by isolating a metal from a solution of its salts under the influence of an electric current. In this case, an auxiliary electrode acts as an anode, which is connected to the positive pole of the current source. The cathode is the part itself on which the galvanic coating is applied.

Classification of galvanic coatings

Taking into account the requirements for the performance characteristics of parts, galvanic coatings can be divided into three types:

— protective and decorative galvanic coatings (used to impart decorative and protective properties to surfaces at the same time);

— protective electrolytic coatings (used to protect parts from corrosion in various aggressive environments);

— galvanic coatings for special purposes (used to give the metal surface certain special properties, such as magnetic, hardness, wear resistance, electrical insulation, etc.). Also, special-purpose galvanic coatings can be applied to restore worn parts

Depending on the mechanism of protective action, all galvanic coatings are divided into: cathodic and anodic. Compared to the potential of the metal being protected, anodic coatings always have a more electronegative potential, and cathodic coatings always have a more electropositive potential. For example, in relation to steel, cadmium and zinc are anodic coatings, and gold, nickel, silver, and copper are cathodic.

The mechanism of the protective action of galvanic coating largely depends not only on the nature of the metal, but also on the composition of the operating environment.

Properties of electrolytic coatings

Surface roughness

Always after the galvanic coating is applied, the surface roughness changes slightly. As a rule, it increases slightly.

Hardness of electrolytically metalized surface

To measure the hardness of the electrolytic coating, the PMT-3 device is used. A diamond pyramid built into it is pressed into the coating under varying loads. Next, the microhardness of the coating is calculated based on the size of the remaining trace (imprint). This Vickers indicator is expressed in megapascals.

Electrical properties

These properties are important in the manufacture of various parts of devices, contacts and much more. These include contact (transition) resistance and electrical conductivity.

When applying galvanic coating, it should be remembered that it also affects the physical and mechanical properties of the base (coated) metal. This is caused by the properties of the coating itself and hydrogenation of the metal being coated.

Hydrogenation of steels leads to a decrease in their ductility. The degree of influence of hydrogen on the mechanical properties of steels strongly depends on its structure (martensite, trostite, austenite, etc.). For example, steel with a cane structure is more embrittled than steel with a sorbitol structure. The strongest effect appears on steels with a martensitic structure. When applying a galvanic protective coating to high-strength steel, which has high internal stresses, there is a risk of cracks.

The influence of galvanic coatings on the properties of the base metal

Fatigue resistance
After electroplating, the base metal is more easily susceptible to fatigue stresses (the fatigue resistance of the metal is reduced). Chrome galvanic coatings have the most powerful effect on steel (especially high-strength grades). This is mainly due to hydrogenation of steel, as well as the low ductility and strength of chromium.

Hydrogenation during electroplating. The strongest hydrogenation is observed when applying electroplating in cyanide electrolytes. In acidic electrolytes, hydrogenation is slightly less, but still sufficient to negatively affect the quality of the base metal.

When applying galvanic coating, the degree of hydrogenation of steel is greatly influenced by: the structure and nature of the coating, the composition of the electrolyte and the current density.

In order to correctly assess the change in the mechanical properties of steel, it is necessary to take into account the influence on it not only of hydrogen, but also of the coating itself, because sometimes the protective coating has less effect than the hydrogen diffused into the surface layers.

For example, the longer the chrome plating process lasts, the more the ductility of steel decreases and hydrogenation increases.

If we evaluate the change in the ductility of steel during chrome plating, taking bending tests of samples with chrome coating as a basis, it turns out that with an increase in the duration of chrome plating (and, as a result, the thickness of the protective layer), the relative fragility decreases.

It follows from this that in order to assess the degree of embrittlement of steel after galvanic coating, the method of testing specimens for bending can only be used for soft elastic coatings. Because in the case of a hard protective layer (like a chrome coating), the method may not give true results about the degree of hydrogenation of steel.

The main influence on the hydrogenation of steel during galvanic coating is the concentration of adsorbed hydrogen atoms, therefore, the time before the onset of steel cracking can also be considered an important parameter for determining the degree of hydrogenation.

So, in order to determine the degree of hydrogenation of steel when applying galvanic coating, you can use:

— ductility in bending of flat samples made of steel with a martensitic structure with an already applied galvanic coating (it is advisable to use this method for zinc and cadmium coatings, i.e. soft);

— ductility of steel with galvanic coating;

— the period of time before the onset of steel destruction during galvanic coating.

Hydrogenation during galvanizing. Galvanizing of steel can be carried out in cyanide, acidic and some other electrolytes.

If the process of applying zinc coating is carried out at pH 4 in a sulfuric acid electrolyte, which does not contain any surfactants (in this case, ik is equal to 1A/dm2), then hydrogenation of steel proceeds very slowly.

With the introduction of a surfactant (for example, aluminum sulfate or dextrin), hydrogenation increases significantly. The same is observed with increasing current density.

When galvanizing U8A steel, 10 g/l of dextrin is added to the heated electrolyte. This reduces hydrogenation.

If the electroplating process is carried out in cyanide electrolytes, then a fairly strong hydrogenation of steel will be observed and, accordingly, a decrease in its ductility. High-strength steels in this electrolyte are more susceptible to hydrogen cracking.

When galvanizing stressed steel 40KhGSN2A at different current densities in an ammonium chloride electrolyte, hydrogen cracking is not observed.

Hydrogenation during chrome plating. When galvanically applying a chrome protective layer, both hydrogenation of the steel and the coating itself is observed, therefore, for a satisfactory final result of the chrome plating process, it is very important to select the correct modes.

The temperature of the electrolyte has a great influence on the amount of hydrogen that penetrates into the steel. At elevated temperatures (about 75°C), hydrogen penetrates more easily into the surface layers of steel. Depending on the nature of the steel, the amount of diffused hydrogen can increase 6 to 10 times.

This is due to the increase in hydrogen diffusion with increasing temperature and the ability of chromium to retain it. Milky chromium in 1 gram can contain about 1.7 - 2.5 cm3 of hydrogen, and shiny chromium - 5.5 - 6.5 cm3.

When bright chrome is applied to the surface, almost 10 times less hydrogen penetrates into the steel than when coated with milky chrome.

In addition to the temperature of the chromium plating electrolyte, the hydrogenation of steel is also greatly influenced by the composition of the solution (together with the electrolysis modes). At ік = 90А/dm2, an increase in the H2SO4 content from 2.5 to 7.5 g/l has a significant effect on the penetration of hydrogen into steel at an electrolyte temperature of about 75°C (diffusion decreases), and when the temperature drops to 55°C there is no special effect observed.

When galvanically applying a chromium coating, the characteristics of the base metal change somewhat. There is a decrease in the ductility of steel. This is especially well observed in the first 10 minutes of the process (hydrogenation increases and plasticity decreases). The intensity of hydrogenation can be judged by the number of hydrogen bubbles that appear on the surface of the steel during the electrolysis process. Towards the middle and towards the end of the chromium plating process, the hydrogenation of steel decreases.

Hydrogenation during etching. The longer the etching process lasts, the more hydrogenation of the metal occurs, and accordingly, the ductility of the steel decreases.

At the beginning of the etching process, the rate of hydrogenation is often maximum, then it gradually decreases. The nature and concentration of the acid also have a great influence on etching. For example, hydrogenation in a solution of hydrochloric acid became less than in H2SO4.

At the same time, with increasing concentration of hydrochloric acid, hydrogenation decreases, and in H2SO4 it increases.

To reduce the degree of hydrogenation of steels during pickling, corrosion inhibitors are additionally introduced into the pickling bath. Not all substances of this type simultaneously reduce the degree of dissolution of the metal in acid and hydrogenation. For example, thiourea in a solution of H2SO4 works very well in protecting metal from corrosion, but it increases hydrogenation. Diethylaniline inhibits the process of hydrogenation and acts as a weak corrosion inhibitor.

Source: https://www.okorrozii.com/galvanicheskoe-pokritie.html

Galvanic coating: properties, types and features of production

This article discusses the scope and features of electroplating.

Galvanization is an electrochemical method of applying a metal film that prevents corrosion and oxidation of surfaces. It gives them an aesthetic appearance, wear resistance and increases hardness.

This processing method improves the heat resistance of metals, so it is widely used in industries where the technological process involves operations carried out at high temperatures.

How did electroplating come about?

The world owes the discovery of electroplating to the Russian physicist Boris Jacobi. In 1836, during experiments, he passed metals through salt and water solutions that were under the influence of an electric current.

When passing through salt solutions, the metals were separated into ions of different charges. The positive ones were deposited on the cathode, and the negative ones on the anode.

Galvanization principle

Galvanic coatings are demanding in terms of surface preparation. Before starting work, it is necessary to thoroughly clean and degrease the bases.

For metal surfaces, it is recommended to use organic solvents that do not cause corrosion.

One such material is MODENGY Metal Cleaner. It perfectly removes petroleum products, silicone oils, preservative compounds, adsorbed films, gases, moisture and other types of contaminants. Evaporates quickly and without residue.

However, cleaning and degreasing alone is not enough in most cases. In addition, sandblasting and subsequent grinding with sandpaper and special pastes are carried out.

Galvanic coating highlights all chips, scratches and cavities on surfaces, so the product being processed must be perfectly prepared.

Next, we will consider galvanization technology.

The cleaned part is immersed in a container with electrolyte and a negative charge is applied to it, as a result of which it becomes a cathode. There is a separate metal plate that receives a positive charge and acts as an anode. It is this that serves to form the coating.

When the electrical network is closed, the metal from the anode plate dissolves in the electrolyte and is directed to the cathode, where it forms a uniform thin film.

This galvanization method is called anodic. Thanks to it, when corrosion occurs, it is the galvanic insulation that is destroyed, and the protected metal remains untouched for a long time.

There is another galvanization method - cathode sputtering. It is used much less frequently. If the integrity of such a coating is damaged, the intensity of destruction of the metal underneath increases. This is facilitated by the application technology itself.

An electrolyte is a conductive solution that allows metals to flow to the cathode from the anode. The size of containers for this liquid may vary and depend on production tasks.

Large parts are suspended in large baths. For smaller products, electroplating is applied in drum tanks, where a negative charge is applied to the drum, which rotates in the electrolyte. To process very small parts (hardware, fasteners), bell-type filling baths are used. During operation, they rotate at low speed, as a result of which the parts are evenly covered with a protective coating.

The current density that passes through the electrolyte is of great importance. It affects the structure of the formed sediment. This value is measured by the ratio of current strength to a unit surface of the workpiece.

If the density is too high, there are a lot of powder deposits, but if it is low, it does not form at all. This affects the quality of the final coating. That is why the galvanization process requires constant monitoring.

The thickness of the galvanic coating on parts is 6-20 microns and is determined by the characteristics of the metals involved in galvanization. The level of adhesion of the metal alloy to surfaces is determined using special tests.

Metal compatibility

Material compatibility during galvanization is very important. All metals in joints corrode. In some cases, this process is slow. However, there are materials that are not recommended to be joined together.

There are certain difficulties associated with working with aluminum and its alloys. This is due to the fact that there is an oxide film on the surfaces of these materials, which complicates the galvanization process.

For aluminum, the following material combinations can be used: nickel-chrome, copper-nickel-chrome, copper-tin, lead-tin. Galvanizing and brass plating of aluminum is also allowed.

Application area

The strength and wear resistance of galvanic coatings allows the use of this type of protection:

• In the aircraft industry
• In mechanical engineering
• In the radio engineering industry
• In the electronics industry
• In construction

Alternative to electroplating

In addition to galvanization, the strength and anti-corrosion characteristics of metals can be increased by hardening, recrystallization, embossing, rolling, flame spraying, surfacing and other processing methods.

One of the simplest and most effective ways to ensure the strength and wear resistance of metal products, prevent their corrosion, and protect them from aggressive external factors is the use of special antifriction coatings (AFC). Outwardly, they resemble paints and varnishes, but instead of color they contain particles of solid lubricants.

AFPs create a thin, dry film on surfaces that has a high load-bearing capacity and a low coefficient of friction. This is especially important for metal parts that are part of moving mechanisms and operate under very high loads, pressures and temperatures.

Let's look at the features of anti-friction coatings using the MODENGY ATSP as an example. They are based on inorganic and organic binders, as well as solid lubricants: graphite, molybdenum disulfide, PTFE, boron nitride, tungsten disulfide, barium and calcium fluorides.

These materials form a durable composite layer on the surfaces, which is a polymer matrix in which particles of solid lubricants are distributed. They fill and smooth out micro-roughness of surfaces, thereby increasing their supporting area and load-bearing capacity.

Antifriction coatings have high compression resistance and low shear resistance, so their coefficient of friction reaches values ​​of several hundredths at contact pressures commensurate with the yield strength of the base material.

Many coatings have proven their performance under radiation and vacuum conditions. They have a high load-bearing capacity of up to 2500 MPa and high extreme pressure characteristics. Thanks to dry lubrication technology, they work effectively in dusty conditions. The operating temperature range of the coatings is from -200 to +560 °C.

AFP is applied using standard staining technologies.

Copper plating

Copper sulfate is used as a coating. This treatment helps to increase the strength of metal products and improve their conductive properties. Copper-plated metals are used to make electrical conductors.

Chrome plating

This procedure improves the strength characteristics of metals, as well as their resistance to aggressive environmental influences. In addition, it improves the appearance and restores damaged parts to their original parameters.

Depending on the technology, chrome coating may have different properties and parameters. For example, matte gray increases the hardness of the metal, but does not increase wear resistance, shiny increases hardness and wear resistance, milky plastic gives an aesthetic appearance, increases corrosion resistance, but does not give hardness to the products.

Galvanizing

The most popular galvanization operation. A thin layer of zinc gives metals a shine and prevents corrosion. Galvanizing is especially popular in the construction and automotive industries. Zinc is used for processing pipe products, containers, support and roofing structures, and car body parts.

Ironing

Used to enhance the strength characteristics of easily worn parts, for example, made of copper. This coating is practically not susceptible to corrosion.

Nickel plating

This processing method is optimal for making metals resistant to external environmental influences. The nickel layer reliably protects products from corrosion resulting from contamination with alkalis, acids, and salts. Nickel-plated parts are very resistant to abrasion and mechanical damage.

Brass plating

Used to protect metals from corrosion. The brass layer provides better adhesion of metal parts to rubber.

Silvering and gilding

These operations are used in jewelry, radio-electronic and electrical industries. Silver and gold give surfaces a presentable appearance, high reflective properties, prevent corrosion, improve conductive properties, increase hardness and protect against aggressive external factors.

Rhodium plating

The rhodium layer increases the resistance of parts to aggressive chemical environments, and also provides additional mechanical resistance. Rhodium plating prevents oxidation, tarnishing of silver items and the aesthetic appearance of metals.

Tin plating

Tin increases the strength and hardness of metal parts. Galvanization with this material is used for aluminum, zinc, steel and copper.

Source: http://atf.ru/articles/obzory/galvanicheskoe-pokrytie-svoystva-raznovidnosti-i-osobennosti-polucheniya/

Technology of galvanic processing of metal parts: coating features

Electroplating is a special electrochemical process that uses an electrolyte, an electric current, a pair of electrodes and the element being processed. This is a unique technology designed for processing metal products. An electrolyte is a liquid substance with high current conductivity, from which, under the influence of an electric current, particles of a metal alloy are released, settling on the element being processed and forming a protective film on its surface.

Galvanic-type coatings are created not by the banal application of a metal layer, but by the penetration of particles into the surface layers of the element.

The essence of the process

Before going into details, you should find out the essence of this electrochemical procedure. Galvanic treatment consists of several important stages:

• production of an electrolyte solution (the composition is selected individually for each situation);
• placing a pair of anodes from the “plus” of the electric current source into the electrolyte;
• immersion of the workpiece in the galvanic composition, placing it between a pair of anodes and subsequent connection to the “minus” of the electric current source (that is, the workpiece becomes a kind of cathode);
• closing the created electrical circuit.

The galvanization process itself is based on the fact that positive particles of the metal alloy present in the electrolyte, under the influence of electric current, tend to the cathode element, which is negatively charged. This composition then settles on the surface of the workpiece and creates a thin film of metal on its surface.

Purposes of Metal Electroplating

There are a variety of purposes for electroplating. For example, for galvanic chrome plating, the surface must first be coated with nickel. Electroplating is usually used to improve the decorative and protective qualities of structures. This procedure is also used to make exact copies of complex elements. In this case, the process is usually called galvanoplasty.

The technology of galvanizing metals through galvanization is widespread. It allows you to create a zinc coating on the surface, which is characterized by excellent anti-corrosion properties.

Products made of metal alloys that have been processed using this technology can retain their properties for a long time at high humidity and even with constant exposure to salt and fresh water.

Galvanizing is also used to process pipe products, all kinds of containers, support and building structures. Thanks to the use of galvanizing, metal surfaces receive both electrochemical and barrier protection.

If galvanizing only increases the resistance of the material to corrosion, then galvanizing with chromium solves this problem, making the surface more wear-resistant and stronger and also improving its appearance. Nickel-based galvanic coatings have a similar effect.

Another area of ​​application of electroplating is the jewelry industry. This technology in this situation is used to improve the appearance of jewelry. In this case, a layer of silver or gold is applied to the jewelry. In addition, the film that is applied to the product during processing makes it brighter and more attractive.

Galvanic processing of various materials involves the use of appropriate “consumables” and equipment. To coat elements with metals, the same type of galvanic installations are used. The difference will only be in the composition of the electrolyte solution used, its temperature and operating modes.

So, the procedure can be performed using the following equipment:

• special baths with electrolyte in which the element being processed and anodes are placed;
• an electric current source that is equipped with an input voltage regulator;
• a heating device that will bring the electrolyte to the desired temperature.

Anode plates are also required, which will supply voltage to the electrolyte and distribute it throughout the element being processed.

It should be noted that hazardous compounds are used , so they must be stored in safe containers.

Any galvanic equipment must be located in areas with good ventilation. You also need to be very careful about safety requirements. All activities associated with galvanic processing must be carried out wearing a protective respirator and goggles, as well as special shoes, an apron and gloves. If electroplating is carried out at home, then you should first study the relevant literature or watch video tutorials on this topic.

Advantages and development history

This technology was invented in 1838 by a scientist named Boris Jacobi . It was he who began the active introduction of galvanics into a variety of production processes. Soon, galvanic processing was successfully mastered by mints, artists, craftsmen, and industrial enterprises.

However, this technique received its name in honor of the Italian scientist Luigi Galvani. He began studying electrochemical processing technology almost simultaneously with Boris Jacobi.

The main advantages of galvanization include the following:

• Electroplated coatings are characterized by uniform thickness and the highest level of density.
• Electroplating can be easily applied even to structures with complex shapes.
• The coating resulting from galvanic treatment has good adhesion to many metals.
• The decorative and protective properties of galvanized parts are very high.
• The thickness of the galvanic coating is very easy to adjust.

By the way, the word “electroplating” is found not only in industrial fields and jewelry production, but also in cosmetology. This is the name of the process in which the skin is exposed to low-power currents to get rid of excess fat from the sebaceous glands.

Source: https://tokar.guru/metally/galvanicheskaya-obrabotka-metalla-osobennosti-pokrytiya.html

What is the essence of the galvanic process?

To understand what electroplating is, it is important to understand the essence of such an electrochemical process. Galvanic processing of a product, during which a thin metal layer is formed on its surface, can be divided into several main stages:

• preparation of an electrolytic solution, the composition of which is selected in each specific case;
• immersion in an electrolytic solution of two anodes connected to the positive contact of a direct current source;
• immersion in a solution for galvanizing the workpiece, placing it between the anodes and connecting it to the negative contact of an electric current source (thus, the workpiece will act as a cathode);
• closing the formed electrical circuit.

Galvanic bath diagram

Galvanic processes that begin to occur in such an electrical circuit consist in the fact that positively charged particles of the applied metal contained in the electrolyte solution, under the influence of electric current, begin to tend to the negatively charged cathode-product, settling on its surface and forming a thin metal film on it .

Execution Goals

Electroplating can be applied to a metal surface for various purposes. For example, to perform galvanic chrome plating, the surface to be treated must be coated with a layer of nickel.

Basically, galvanic coatings are applied in order to improve the protective properties and decorative characteristics of products. Electroplating is also used to create exact copies of parts that even have a very high complexity of relief.

In such cases, the process is called galvanoplasty.

The method of galvanizing ferrous metals using galvanization is widely used. It allows you to form a layer of zinc on their surface, which is characterized by exceptionally high resistance to corrosion.

Metal products processed using this technology can be used for a very long time in conditions of high humidity, in constant contact with fresh and salt water, without losing their original characteristics.

Galvanizing is used, in particular, to process pipe products, various containers, and elements of roofing, building and supporting structures. Due to galvanizing, the metal receives not only barrier, but also electrochemical protection.

Galvanizing a car body in a galvanic bath

If with the help of galvanizing only the corrosion resistance of the metal is increased, then electroplating with chromium allows not only to solve this important problem, but also to make the surface of the workpiece harder and more wear-resistant, and also to increase its decorative appeal. Electroplated nickel coatings serve the same purposes.

Jewelry making is another area where electroplating plays a special role. Galvanization in this case is used to improve the decorative characteristics of the processed products.

The electroplating process is used to coat a piece of jewelry with a layer of gold or silver, restoring a surface that has lost its appeal over time.

It is noteworthy that even gold products are subjected to gilding using electroplating, which makes it possible to almost double the hardness of their surface layer. In addition, such a film applied to a gold product seems to illuminate it, making it brighter and more beautiful.

Brief history of the development and advantages of electroplating

The date of development of the method of galvanic deposition (or rather, one of its varieties - galvanoplasty) is considered to be 1838, when it was invented by the famous scientist Boris Jacobi. After developing this technology, the scientist began to actively introduce it into various production processes, due to which mints and enterprises engaged in the production of printing equipment, as well as specialists in artistic crafts, began to use it.

In the Middle Ages, a galvanic bath was used to make copies of medals, which were dipped into a solution as a cathode (m)

The most significant advantages of coating products with a layer of metal using galvanization include the following.

• Galvanic coatings can be applied without problems to parts with even very complex configurations.
• The coating formed using this technology is characterized by high density and uniform thickness.
• The coating applied by electroplating is characterized by excellent adhesion to the treated surface.
• The protective and decorative characteristics of galvanized coatings, if they are formed in strict accordance with technological requirements, are at the highest level.
• The thickness of the metal layer applied by electroplating can be easily adjusted.

It is also important that the electroplating technology is already well developed and is not highly complex, and its practical implementation does not require significant financial investments.

Electroplating technology is so accessible that it allows you to independently create installations that are quite competitive with factory models

The term “plating” can be encountered not only in various industries and jewelry, but also in cosmetology.

  How to glue silicone rubber to metal

The process that is implied by this name of a cosmetic procedure can hardly be called galvanization in the full sense of the word, however, the term has taken root, and galvanic cleansing of facial skin is very popular in our time.

When performing such cleansing, the skin is exposed to low-power currents, due to which the fats accumulated in its deep layers are liquefied and easily come out through the pores.

Source: http://ooo-asteko.ru/galvanizirovannyy-metall-chto-eto/

Electroplating at home

The discovery of the galvanization method, made by the Russian physicist Boris (Maurice) Jacobi in 1838, separated into two independent branches of electroplating technology: electroplating and electroplating. Electroplating on an industrial scale allows the use of this electrochemical process of deposition of metal cations on any surface. Electroplating at home will help you obtain such a coating on the selected substrate.

Galvanic coating of products

Necessary equipment

Galvanic processing of small products at home requires certain equipment and chemical reagents. The main list of equipment includes:

• DC power supply;
• capacity;
• electrolyte;
• scales;
• electrodes “anode” and “cathode”;
• the wire;
• electric stove.

Source: https://amperof.ru/teoriya/galvanika-v-domashnix-usloviyax.html

What is the galvanization process

Redox reactions occur in electrochemical cells. An electrochemical cell can operate in two modes as:

• electrolytic cell (electrolyzer);
• galvanic cell (galvanic cell).

When an energy source is connected to the external circuit of the cell, the electrical energy will be converted into chemical energy, and electrolysis will occur in the cell. The anode of the electrolytic cell is positive, the cathode is negative. The anode attracts anions from the solution. In both galvanic and electrolytic cells, oxidation occurs at the anode, and electrons flow from the anode to the cathode.

For information. A galvanic cell is a source of electric current, and an electrolyzer is a consumer of electric current.

Galvanic pair of electrodes

The galvanic couple is installed in different containers connected through a salt bridge or porous section.

In a galvanic cell, the anode is the negative electrode because electrons remain on the electrode during oxidation. Metal atoms give up electrons and become positively charged ions. The remaining electrons make the anode negatively charged, and electrons flow from the anode through the wire to the cathode. The cathode of a galvanic cell is its positive terminal.

Chemical reactions occur at these electrodes: oxidation at the anode, reduction at the cathode.

Rechargeable batteries

The redox reaction in a galvanic cell is a spontaneous reaction. For this reason, voltaic cells are commonly used as batteries. Thanks to the reaction of galvanic cells, energy is supplied that is used to perform work.

Electric batteries are rechargeable galvanic cells. They can be recharged using an external energy source. The operation of such a device takes place in the form of the following electrode processes:

• galvanic discharge;
• charger.

To do this, the battery is connected to an external current source in such a way that a negative pole is supplied to the “anode” terminal, and a positive pole is supplied to the “cathode” terminal. When the two poles of a battery are connected to each other through any conductor of electricity, a phenomenon occurs - galvanic current.

Galvanic current

A galvanic cell converts chemical energy into electrical energy. What is galvanic current? Galvanic current is a continuous current that has a fairly low voltage and a low constant level of intensity. Galvanic current is only a special case of the phenomenon of electric current.

Technologies

Electroplating includes two electrochemical technologies:

• electrotype,
• galvanostegy.

Galvanoplasty and galvanostegy differ in the methods of preparing the surface before depositing metal on it.

Electrotype

Electroplating is a chemical method of forming metal parts as exact copies of models. The method was invented by Moritz von Jacobi in Russia in 1838 and was immediately adopted for use in printing and several other fields. The process used in electroforming is electrodeposition (the electroplating couple is immersed in a solution called an electrolyte).

Using galvanoplasty, an exact copy of any object that has an uneven surface is produced, be it:

• an engraved steel or copper plate cut from wood, or a printing plate;
• a medal, medallion, figurine, bust or even a natural object for artistic purposes.

In art, the method is used to create bronze sculptures. In printing, electroforming has become the standard method of producing plates for printing.

Galvanostegy

Galvanostegy is an electrochemical technology of coating one metal with another that is more mechanically and chemically stable. For example, steel is coated with chromium, nickel, copper with nickel, silver or other metals.

For information. In practice, aluminum is not coated with other metals.

Electroplating

Application examples

Galvanization allows you to do things like:

• placing signboards on highways,
• installation of bridge beams, telephone poles.

Thanks to this technology, any structure exposed to the atmosphere can be used. For example, if you take plain steel and then galvanize it, you can significantly reduce costs while providing long-term protection of equipment and material from corrosion.

Galvanization is carried out by immersing clean steel products in a bath of molten zinc. Galvanic baths for hot-dip galvanizing look like the one shown in the image below. When a metal is immersed in a bath, a complex interaction of the metal with the components of the solution begins.

Gold electroplating

Galvanizing

Electrolytic galvanizing produces a thin, shiny coating. For galvanization, galvanic baths are used - tanks for hot-dip galvanizing in a molten state. In this case, the galvanic coating is applied in a thicker layer, resulting in a dull gray color. For example, for the installation of outdoor switchboard equipment, galvanized screws, washers and nuts are purchased.

In galvanized steel, zinc is only on the surface. Therefore, when cutting galvanized steel, you can see its “unprotected” part.

However, one of the beneficial features of galvanizing is that the exposed steel will not actually start to rust until all the zinc has been oxidized. The zinc acts as a "sacrificial anode" that protects the steel.

Thus, it is possible to scratch the galvanized steel piece, drill holes, etc. The material will still remain resistant to corrosion for quite a significant period of time.

Galvanic baths

For information. Galvanized steel is steel whose surface is coated with a thin layer of zinc. The latter provides protection of the material from corrosion. Stainless steel is a completely different class of material.

It's steel mixed with chrome. When exposed to the atmosphere, chromium forms a thin protective film of chromium oxide on the surface, which protects the base material from further oxidation.

Since chromium is distributed over the entire surface, the material can be drilled, cut, etc.

Galvanic isolation

Galvanic isolation provides insulation between electrical circuits. There are two reasons to provide isolation:

• For safety from malfunction. If two circuits are galvanically isolated, then the failure of one of them will not affect the other;
• To prevent the flow of stray currents.

For information. Galvanic isolation is the principle of separating functional sections of electrical systems. An example would be a transformer with galvanically isolated input and output.

Galvanic isolation block BGR

What is galvanization and what is it used for?

Cathode and anode in theory and practice

Electroplating is a frequently used method for changing the surface properties of metals. The electroplating process involves using an electrical current to mobilize metal cations from an electrode immersed in a solution. The most common reasons for galvanization are:

• reducing abrasive wear, increasing wear resistance;
• protection against corrosion (when the material is in chemically difficult conditions);
• aesthetics (gold, silver, shiny chrome and many other colors).

Metal electroplating

Galvanic coating is used to increase wear resistance, corrosion resistance, and aesthetic qualities. Thanks to galvanization, the cost of products made from precious metals, such as gold, is reduced and the properties of the material are improved. For example, chromium coating of carbon steel provides strength and chemical resistance to the surface of the material.

Current unit

Source: https://steelfactoryrus.com/galvanizirovannyy-metall-chto-eto/