Unified system of protection against corrosion and aging. Application of the Spramet™ system for corrosion protection Corrosion hazard criteria

The development of the steel industry is inextricably linked with the search for ways and means to prevent the destruction of metal products. Protection against corrosion and the development of new techniques is a continuous process in the technological chain of production of metal and products made from it. Iron-containing products become unusable under the influence of various physical and chemical external environmental factors. We see these consequences in the form of hydrated iron residues, that is, rust.

Methods for protecting metals from corrosion are selected depending on the operating conditions of the products. Therefore it stands out:

• Corrosion associated with atmospheric phenomena. This is a destructive process of oxygen or hydrogen depolarization of a metal. Which leads to the destruction of the crystalline molecular lattice under the influence of a humid air environment and other aggressive factors and impurities (temperature, the presence of chemical impurities, etc.).
• Corrosion in water, primarily sea water. In it, the process goes faster due to the content of salts and microorganisms.
• Destruction processes that occur in the soil. Soil corrosion is a rather complex form of metal damage. Much depends on the composition of the soil, humidity, heating and other factors. In addition, products, for example, pipelines, are buried deep in the ground, which makes diagnostics difficult. And corrosion often affects individual parts pointwise or in the form of ulcerative veins.

Types of corrosion protection are selected individually, depending on the environment in which the metal product being protected will be located.

Typical types of rust damage

Methods for protecting steel and alloys depend not only on the type of corrosion, but also on the type of destruction:

• Rust covers the surface of the product in a continuous layer or in separate areas.
• It appears in the form of spots and penetrates pointwise into the depths of the part.
• Destroys the metal molecular lattice in the form of a deep crack.
• In a steel product consisting of alloys, destruction of one of the metals occurs.
• Deeper extensive rusting, when not only the surface is gradually damaged, but also penetration occurs into the deeper layers of the structure.

The types of damage can be combined. Sometimes they are difficult to determine immediately, especially when point destruction of steel occurs. Corrosion protection methods include special diagnostics to determine the extent of damage.

They produce chemical corrosion without generating electrical currents. Upon contact with petroleum products, alcohol solutions and other aggressive ingredients, a chemical reaction occurs, accompanied by gas emissions and high temperature.

Galvanic corrosion is when a metal surface comes into contact with an electrolyte, specifically water from the environment. In this case, diffusion of metals occurs. Under the influence of the electrolyte, an electric current arises, the replacement and movement of electrons of the metals that are included in the alloy occurs. The structure is destroyed and rust forms.

Steelmaking and its corrosion protection are two sides of the same coin. Corrosion causes enormous damage to industrial and commercial buildings. In cases with large-scale technical structures, for example, bridges, power poles, barrier structures, it can also provoke man-made disasters.

Metal corrosion and methods of protection against it

How to protect metal? There are many corrosion methods for metals and ways to protect against it. To protect metal from rust, industrial methods are used. In everyday life, various silicone enamels, varnishes, paints, and polymer materials are used.

Industrial

Protection of iron from corrosion can be divided into several main areas. Methods of protection against corrosion:

• Passivation. When producing steel, other metals are added (chromium, nickel, molybdenum, niobium and others). They are distinguished by increased quality characteristics, refractoriness, resistance to aggressive environments, etc. As a result, an oxide film is formed. These types of steel are called alloyed.

• Surface coating with other metals. Various methods are used to protect metals from corrosion: electroplating, immersion in a molten composition, application to the surface using special equipment. As a result, a metal protective film is formed. Chromium, nickel, cobalt, aluminum and others are most often used for these purposes. Alloys (bronze, brass) are also used.

• The use of metal anodes, protectors, often made of magnesium alloys, zinc or aluminum. As a result of contact with the electrolyte (water), an electrochemical reaction begins. The protector breaks down and forms a protective film on the surface of the steel. This technique has proven itself well for underwater parts of ships and offshore drilling rigs.

• Acid etching inhibitors. The use of substances that reduce the level of environmental impact on metal. They are used for preservation and storage of products. And also in the oil refining industry.

• Corrosion and protection of metals, bimetals (cladding). This is coating steel with a layer of another metal or a composite composition. Under the influence of pressure and high temperatures, diffusion and bonding of surfaces occurs. For example, well-known heating radiators made of bimetal.

Metal corrosion and methods of protection against it used in industrial production are quite diverse, such as chemical protection, glass enamel coating, and enameled products. Steel is hardened at high temperatures, over 1000 degrees.

On video: galvanizing metal as protection against corrosion.

Household

Protecting metals from corrosion at home is, first of all, chemicals for the production of paints and varnishes. The protective properties of the compositions are achieved by combining various components: silicone resins, polymer materials, inhibitors, metal powder and shavings.

To protect the surface from rust, it is necessary to use special primers or a rust converter before painting, especially old structures.

What types of converters are there:

• Primers - provide adhesion, adhesion to metal, level the surface before painting. Most of them contain inhibitors that significantly slow down the corrosion process. Preliminary application of a primer layer can significantly save paint.
• Chemical compounds - convert iron oxide into other compounds. They are not subject to rust. They are called stabilizers.
• Compounds that convert rust into salts.
• Resins and oils that bind and seal rust, thereby neutralizing it.

These products contain components that slow down the process of rust formation as much as possible. Converters are included in the product line of manufacturers producing metal paints. They vary in consistency.

It is better to choose primer and paint from the same company so that they match the chemical composition. You must first decide which methods you will choose to apply the composition.

Protective paints for metal

Metal paints are divided into heat-resistant, which can be used at high temperatures, and for normal temperatures up to eighty degrees. The following main types of metal paints are used: alkyd, acrylic, epoxy paints. There are special anti-corrosion paints. They are two- or three-component. They are mixed immediately before use.

Advantages of paintwork for metal surfaces:

• protect surfaces well from temperature changes and atmospheric fluctuations;
• can be applied quite easily in different ways (brush, roller, spray gun);
• most of them are quick-drying;
• wide range of colors;
• long service life.

Of the inexpensive means available, you can use ordinary silverware. It contains aluminum powder, which creates a protective film on the surface.

Two-component epoxy compounds are suitable for protecting metal surfaces that are subject to increased mechanical stress, in particular the underbody of cars.

Metal protection at home

Corrosion and methods of protecting against it at home require compliance with a certain sequence:

1. Before applying a primer or rust converter, the surface is thoroughly cleaned of dirt, oil stains, and rust. Use metal brushes or special attachments for grinders.

2. Then apply a primer layer, allow it to soak in and dry.

Protecting metals from corrosion is a complex process. It begins at the stage of steel smelting. It is difficult to list all the methods for combating rust, since they are constantly being improved, not only in industry, but also for domestic use. Manufacturers of paint and varnish products are constantly improving their compositions, increasing their corrosion properties. All this significantly extends the service life of metal structures and steel products.

Corrosion protection system: how and why?

The disadvantage of such a material as metal is that corrosion can occur on it. Today there are several methods, they need to be used in combination. The corrosion protection system will help get rid of rust and prevent the formation of layers.

Treating a metal surface with a special coating is an effective method. The metal coating increases the hardness and strength of the material and improves the mechanical properties. It should be borne in mind that in this case additional protection will be required. Non-metallic coating is applied to ceramics, rubber, plastic, wood.

Methods of protection against corrosion

Film-forming coatings are most often used; they are resistant to the external environment. A film forms on the surface, which inhibits corrosion processes.

In order to reduce corrosive activity, it is necessary to neutralize the environment exposed to its influence. Inhibitors will help you with this; they are introduced into an aggressive environment, and a film is formed that inhibits processes and changes the chemical parameters of the metal.

Alloying is widely used; it increases properties that help increase the resistance of the material to corrosion processes. Alloy steel contains a lot of chromium; it forms films that protect the metal.

It would be a good idea to use protective films. Anodic coatings are used for zinc and chromium, cathodic coatings are used for tin, nickel, and copper. They are applied using the hot method, and galvanization can also be used. The product must be placed in a container containing the protective metal in a molten state.

By using metallization, corrosion can be avoided. The surface is covered with metal, which is in a molten state, and it is sprayed with air. The advantage of this method is that it can be used to cover ready-made and fully assembled structures. The downside is that the surface will be a little rough. Such coatings are applied by diffusion into the base metal.

The coating can be protected with an oxide film, this procedure is called oxidation. The oxide film that exists on the metal is treated with a powerful oxidizing agent, as a result of which it becomes several times stronger.

Phosphating is also used in industry. Iron salts are immersed in a hot phosphate solution, eventually forming a surface film.

For temporary surface protection, it is necessary to use ethinol, technical petroleum jelly, and inhibitors. The latter slow down the reaction, resulting in corrosion developing much more slowly.

The paint and varnish and galvanic coatings currently used for corrosion protection have significant drawbacks. As for paint and varnish coatings, first of all, these are a low degree of reliability in case of mechanical damage, a low resource of single-layer coatings and the high cost of multi-layer coatings. Damage to the coating to the protected metal leads to the development of under-film corrosion. In this case, the aggressive environment gets under the insulating layer of paint and varnish, and corrosion of the base metal begins, which actively spreads under the paint layer, which leads to peeling of the protective layer.

As for electroplating, once the required properties are achieved, the electrolyte is sensitive to temperature fluctuations throughout the deposition process, which usually lasts several hours. Electroplating also involves the use of materials and chemicals, many of which are quite harmful. Metallization and paint and varnish coatings compete with paint and varnish, galvanic, as well as glass-enamel, bitumen, bitumen-rubber, polymer and epoxy coatings and electrochemical protection. Spramet™.

Spramet™- a set of combined metallization and paint coatings for protection against corrosion for up to 50 years, each of which has additional properties - heat resistance, fire retardant characteristics, heat insulating characteristics, etc.

Spramet™ systems are applied both in production conditions and in repair conditions - at the site of operation of the facility. Spramet's high resistance to mechanical damage, the absence of under-film corrosion and prices comparable to high-quality painting make this system an ideal choice for long-term corrosion protection of especially dangerous and unique objects.

Under the influence of the main operational aging factors (time, combined temperature and moisture, aggressive environments, differences in electrochemical potentials), the system Spramet protection does not change its original properties, withstands heating up to 650°C, has high mechanical characteristics: wear resistance, flexibility, and also actively resists corrosion. Spramet effectively protects welds and retains its protective and decorative properties throughout the entire period of operation.

In total, the operating costs of products protected with Spramet systems are 2-4 times less compared to paint and varnish or other coatings known today.

CJSC "Plakart" conducted large-scale tests and began using compositions Spramet™— protective corrosion protection systems based on metal matrices. These compositions consist of one or more layers. The basis of the composition is a metal matrix: sprayed aluminum, zinc or their alloys. To improve performance properties, an impregnating layer is applied to close the pores, then a protective or heat-insulating layer, as well as a tinting layer.

IN JSC "Plakart" A line of compositions has been developed to solve problems under various operating conditions:

• Spramet-ANTIKOR
• Spramet-TERMO
• Spramet-NON-SLIP
• Spramet-NANO

Benefits compositions by Spramet are:

• higher hardness,
• resistance to abrasive wear.

To increase the protective properties, metal coatings are impregnated with special compounds. Spramet protection systems guarantee a service life of objects from 15 to 50 years of service without corrosion.

The corrosion resistance of Spramet compositions is due to the following factors:

• firstly, the base metallization layer of the Spramet system itself protects the surface well from corrosion;
• secondly, impregnation of the porous structure of the metal matrix with special compounds enhances the anti-corrosion properties of the system in a wide range of aggressive environments and temperatures;
• thirdly, if the Spramet composition is damaged before the protected material, another protection mechanism comes into play, namely a protector, which does not allow the development of under-film corrosion and delays local damage.

If the metal matrix is ​​damaged in an aggressive environment, the protected metal and the coating metal form a galvanic couple in the presence of water. The potential difference in such a circuit is determined by the location of the metals in the electrochemical voltage series. Since the material being protected is typically ferrous metals, the coating material begins to be consumed, protecting the base metal and sealing the damaged area. In this case, the corrosion rate is determined by the difference in the electrode potentials of the pair. In addition, if the damage to the coating is minor (scratches), it is filled with oxidation products of the coating material, and the corrosion process stops or slows down significantly. For example, in sea and fresh water, aluminum and zinc are consumed at a rate of 3-10 microns per year, providing at least 25 years of corrosion resistance at a layer thickness of 250 microns.

The advantages of product processing protective compositions Spramet include the following:

• no restrictions on product sizes compared to hot-dip galvanizing and galvanizing;
• the ability to protect welds after installation of the structure (in the case of welding galvanized products, the quality of the seam deteriorates due to zinc compounds entering the weld pool);
• the possibility of applying Spramet protection in the field, which is not feasible either in the case of galvanizing or in the case of powder coating.

Some options for using the Spramet protection system

Spramet-ANTIKOR

• Spramet-100 is a system that is resistant to corrosion and mechanical stress both under normal conditions and at temperatures up to 650°C.
• Spramet-130 is used for protection against corrosion in fresh water; it has good resistance to the effects of water of various compositions and the mechanical effects of ice.
• Spramet-150 is used for atmospheric corrosion, has good chemical resistance, and is used for storing petroleum products.
• Spramet-300 is used for atmospheric corrosion, operating temperatures up to 400°C, and has high adhesion.
• Spramet-310 is best used in heat and water supply facilities, and is resistant to inhibitors in water treatment systems.
• Spramet-320 is used in wastewater treatment plants for housing and communal services: it has high resistance to the effects of liquids with variable pH.
• Spramet-330 is used for atmospheric corrosion and corrosion in fresh water at operating temperatures up to 120°C; it is resistant to mechanical stress and has high adhesion.
• Spramet-430 is used for protection against atmospheric corrosion in the presence of chlorides, is resistant to deicing agents and has a decorative effect.
• Spramet-425 is best used for protection against corrosion in sea water, is resistant to mechanical stress, including ice, and has good resistance to chlorides.

Spramet-TERMO

Anti-corrosion high temperature system. Operating temperature - up to 650°C.

• Spramet-100 is a corrosion-resistant system both under normal conditions and at temperatures up to 650°C.
• Spramet-160. The metal matrix is ​​coated with a certified fire retardant compound that foams when exposed to high temperatures and provides fire resistance of up to 60 minutes.

Spramet-NON-SLIP Spramet-500 and 510 provide roughness of the treated surface, which prevents slipping of personnel and equipment. Applicable to metal walkways of offshore platforms, helipads, decks and other pedestrian metal walkways. Spramet-NANO In this case, the metal matrix is ​​a nanostructured coating. Such a coating has even lower porosity, much higher resistance to corrosion and erosive wear, and increased heat resistance, which significantly increases the service life of the protected product.

Due to the increased reliability and durability of the composition, Spramet is recommended for use when increased demands are placed on the protected object: a significant increase in the turnaround time or provision of anti-corrosion protection for the entire period of operation of metal structures, as well as in the absence of access to restore protective coatings.

Practical application (2011)

Specialists of ZAO Plakart have completed work on applying the system Spramet-100 for protection against corrosion of exhaust shafts of gas pumping units of the main gas pipeline system of OJSC Gazprom. The system is resistant to corrosion both under normal conditions and at temperatures up to 650°C, has an even white surface color, and is not afraid of mechanical damage, temperature changes and ultraviolet radiation.

Work on applying a corrosion-resistant system has been completed Spramet-300 on the crossbars of one of the cable-stayed bridges of the Alpika-Service Olympic route. Olympic venues operating in difficult climatic conditions require guaranteed long-term corrosion protection. System Spramet-ANTIKOR not only provides excellent protection against corrosion, but also serves as an excellent primer for paintwork.

Work on applying the protection system has been completed Spramet-150 on the internal surfaces of petroleum product storage tanks in the Astrakhan region. This anti-corrosion system was applied to tens of thousands of square meters of the internal surfaces of the tank and the pontoon floating in it.

From a standardization point of view "Spramet" system belongs to the group of combined metallization-paint and varnish coatings recommended for use on particularly dangerous and unique objects SNIP 2.03.11 “Protection of building structures from corrosion”, as well as many industry and ISO standards.

Quality system JSC "Plakart" certified according to ISO 9001. CJSC Plakart is a member of the self-regulatory organizations Zapaduralstroy and Sopkor. Trademark Spramet™ registered and owned by Plakart CJSC.

These methods can be divided into 2 groups. The first 2 methods are usually implemented before the start of production operation of the metal product (selection of structural materials and their combinations at the stage of design and manufacture of the product, application of protective coatings to it). The last 2 methods, on the contrary, can only be carried out during the operation of the metal product (passing current to achieve a protective potential, introducing special inhibitor additives into the process environment) and are not associated with any pre-treatment before use.

The second group of methods allows, if necessary, to create new protection modes that ensure the least corrosion of the product. For example, in certain sections of the pipeline, depending on the aggressiveness of the soil, the cathode current density can be changed. Or use different inhibitors for different types of oil pumped through pipes.

Question: How are corrosion inhibitors used?

Answer: To combat metal corrosion, corrosion inhibitors are widely used, which are introduced in small quantities into an aggressive environment and create an adsorption film on the metal surface, inhibiting electrode processes and changing the electrochemical parameters of metals.

Question: What are the ways to protect metals from corrosion using paints and varnishes?

Answer: Depending on the composition of pigments and the film-forming base, paint and varnish coatings can serve as a barrier, passivator or protector.

Barrier protection is the mechanical insulation of a surface. Violation of the integrity of the coating, even at the level of the appearance of microcracks, predetermines the penetration of an aggressive environment to the base and the occurrence of under-film corrosion.

Passivation of a metal surface using paintwork is achieved through chemical interaction between the metal and the coating components. This group includes primers and enamels containing phosphoric acid (phosphating), as well as compositions with inhibitory pigments that slow down or prevent the corrosion process.

Protective protection of metal is achieved by adding powdered metals to the coating material, creating donor electron pairs with the protected metal. For steel these are zinc, magnesium, aluminum. Under the influence of an aggressive environment, the additive powder gradually dissolves, and the base material is not subject to corrosion.

Question: What determines the durability of metal protection against corrosion using paints and varnishes?

Answer: Firstly, the durability of metal protection from corrosion depends on the type (and type) of paint and varnish coating used. Secondly, the thoroughness of preparing the metal surface for painting plays a decisive role. The most labor-intensive process in this case is the removal of previously formed corrosion products. Special compounds are applied that destroy rust, followed by mechanical removal with metal brushes.

In some cases, rust removal is practically impossible, which requires the widespread use of materials that can be applied directly to surfaces damaged by corrosion - rust coating materials. This group includes some special primers and enamels used in multi-layer or independent coatings.

Question: What are high-fill two-component systems?

Answer: These are anti-corrosion paints and varnishes with a reduced solvent content (the percentage of volatile organic substances in them does not exceed 35%). The market for materials for home use mainly offers single-component materials. The main advantage of highly filled systems compared to conventional ones is significantly better corrosion resistance at a comparable layer thickness, lower material consumption and the possibility of applying a thicker layer, which ensures the required anti-corrosion protection in just 1-2 times.

Question: How to protect the surface of galvanized steel from destruction?

Answer: Anti-corrosion primer based on modified vinyl acrylic resins in the Galvaplast solvent is used for interior and exterior work on descaled ferrous metal substrates, galvanized steel, and galvanized iron. Solvent – ​​white spirit. Application – brush, roller, spray. Consumption 0.10-0.12 kg/sq.m; drying 24 hours.

Question: What is patina?

Answer: The word “patina” refers to a film of various shades that forms on the surface of copper and copper-containing alloys under the influence of atmospheric factors during natural or artificial aging. Sometimes patina refers to oxides on the surface of metals, as well as films that cause tarnish on the surface of stones, marble or wooden objects over time.

The appearance of patina is not a sign of corrosion, but rather a natural protective layer on the copper surface.

Question: Is it possible to artificially create a patina on the surface of copper products?

Answer: Under natural conditions, a green patina forms on the surface of copper within 5-25 years, depending on climate and the chemical composition of the atmosphere and precipitation. At the same time, copper carbonates are formed from copper and its two main alloys - bronze and brass: bright green malachite Cu 2 (CO 3) (OH) 2 and azure blue azurite Cu 2 (CO 3) 2 (OH) 2. For zinc-containing brass, the formation of green-blue rosasite with the composition (Cu,Zn) 2 (CO 3)(OH) 2 is possible. Basic copper carbonates can be easily synthesized at home by adding an aqueous solution of soda ash to an aqueous solution of a copper salt, such as copper sulfate. At the same time, at the beginning of the process, when there is an excess of copper salt, a product is formed that is closer in composition to azurite, and at the end of the process (with an excess of soda) - to malachite.

Saving coloring

Question: How to protect metal or reinforced concrete structures from the influence of aggressive environments - salts, acids, alkalis, solvents?

Answer: To create chemical-resistant coatings, there are several protective materials, each of which has its own area of ​​protection. The widest range of protection is provided by: enamels XC-759, “ELOCOR SB-022” varnish, FLC-2, primers, XC-010, etc. In each individual case, a specific painting scheme is selected, according to operating conditions. Tikkurilla Coatings Temabond, Temacoat and Temachlor paints.

Question: What compositions can be used when painting the internal surfaces of tanks for kerosene and other petroleum products?

Answer: Temaline LP is a two-component epoxy gloss paint with an amino adduct-based hardener. Application - brush, spray. Drying 7 hours.

EP-0215 ​​– primer for corrosion protection of the internal surface of caisson tanks operating in a fuel environment with an admixture of water. It is applied to surfaces made of steel, magnesium, aluminum and titanium alloys operated in various climatic zones, at elevated temperatures and exposure to polluted environments.

Suitable for use with BEP-0261 primer and BEP-610 enamel.

Question: What compounds can be used for protective coating of metal surfaces in marine and industrial environments?

Answer: Thick film paint based on chlorinated rubber is used for painting metal surfaces in marine and industrial environments exposed to moderate chemical exposure: bridges, cranes, conveyors, port equipment, tank exteriors.

Temacoat CB is a two-component modified epoxy paint used for priming and painting metal surfaces exposed to atmospheric, mechanical and chemical influences. Application - brush, spray. Drying time: 4 hours.

Question: What compositions should be used to coat difficult-to-clean metal surfaces, including those immersed in water?

Answer: Temabond ST-200 is a two-component modified epoxy paint with aluminum pigmentation and low solvent content. Used for painting bridges, tanks, steel structures and equipment. Application - brush, spray. Drying – 6 hours.

Temaline BL is a two-component epoxy coating that does not contain solvents. Used for painting steel surfaces exposed to wear, chemical and mechanical stress when immersed in water, containers for oil or gasoline, tanks and reservoirs, wastewater treatment plants. Application by airless spray.

Temazinc is a one-component zinc-rich epoxy paint with a polyamide-based hardener. Used as a primer in epoxy, polyurethane, acrylic, chlorinated rubber paint systems for steel and cast iron surfaces exposed to strong atmospheric and chemical influences. Suitable for painting bridges, cranes, steel frames, steel structures and equipment. Drying 1 hour.

Question: How to protect underground pipes from the formation of fistulas?

Answer: There can be two reasons for any pipe burst: mechanical damage or corrosion. If the first reason is the result of accident and carelessness - the pipe is caught by something or the weld has come apart, then corrosion cannot be avoided; this is a natural phenomenon caused by soil moisture.

In addition to the use of special coatings, there is protection that is widely used throughout the world - cathodic polarization. It is a direct current source providing a polar potential of min 0.85 V, max – 1.1 V. It consists only of a conventional AC voltage transformer and a diode rectifier.

Question: How much does cathodic polarization cost?

Answer: The cost of cathodic protection devices, depending on their design, ranges from 1000 to 14 thousand rubles. The repair team can easily check the polarization potential. Installing protection is also not expensive and does not involve labor-intensive excavation work.

Protection of galvanized surfaces

Question: Why can't galvanized metals be shot blasted?

Answer: Such preparation violates the natural corrosion resistance of the metal. Surfaces of this kind are treated with a special abrasive agent - round glass particles that do not destroy the protective layer of zinc on the surface. In most cases, it is enough to simply treat with an ammonia solution to remove grease stains and zinc corrosion products from the surface.

Question: How to restore damaged zinc coating?

Answer: Zinc-filled compositions ZincKOS, TsNK, “Vinikor-zinc”, etc., which are applied by cold galvanizing and provide anodic protection of the metal.

Question: How is metal protected using ZNC (zinc-filled compositions)?

Answer: Cold galvanizing technology using CNC guarantees absolute non-toxicity, fire safety, and heat resistance up to +800°C. Coating of metal with this composition is carried out by spraying, with a roller or even just with a brush and provides the product with, in fact, double protection: both cathodic and film. The validity period of such protection is 25-50 years.

Question: What are the main advantages of the cold galvanizing method over hot galvanizing?

Answer: This method has the following advantages:

1. Maintainability.
2. Possibility of application on a construction site.
3. There are no restrictions on the overall dimensions of protected structures.

Question: At what temperature is thermal diffusion coating applied?

Answer: Thermal diffusion zinc coating is applied at temperatures from 400 to 500°C.

Question: Are there any differences in the corrosion resistance of coatings obtained by thermal diffusion galvanizing compared to other types of zinc coatings?

Answer: The corrosion resistance of thermal diffusion zinc coating is 3-5 times higher than galvanic coating and 1.5-2 times higher than the corrosion resistance of hot zinc coating.

Question: What paint and varnish materials can be used for protective and decorative painting of galvanized iron?

Answer: For this, you can use both water-based ones - G-3 primer, G-4 paint, and organo-thinned ones - EP-140, "ELOCOR SB-022", etc. Tikkurila Coatings protective systems can be used: 1 Temakout GPLS-Primer + Temadur, 2 Temaprime EE+Temalak, Temalak and Temadur are tinted according to RAL and TVT.

Question: What paint can be used to paint galvanized drainage pipes?

Answer: Sockelfarg is a water-based latex paint in black and white. Designed for application to both new and previously painted outdoor surfaces. Resistant to weather conditions. Solvent – ​​water. Drying 3 hours.

Question: Why are water-based anti-corrosion agents rarely used?

Answer: There are 2 main reasons: the increased price compared to conventional materials and the prevailing opinion in certain circles that water systems have worse protective properties. However, as environmental legislation becomes stricter, both in Europe and throughout the world, the popularity of water systems is growing. Experts who tested high-quality water-based materials were able to verify that their protective properties are no worse than those of traditional materials containing solvents.

Question: Which device is used to determine the thickness of the paint film on metal surfaces?

Answer: The “Constant MK” device is the easiest to use - it measures the thickness of paintwork on ferromagnetic metals. Much more functions are performed by the multifunctional thickness gauge "Constant K-5", which measures the thickness of conventional paintwork, galvanic and hot-zinc coatings on both ferromagnetic and non-ferromagnetic metals (aluminum, its alloys, etc.), and also measures surface roughness, temperature and air humidity, etc.

The rust is receding

Question: How can I treat items that are heavily corroded by rust?

Answer: First recipe: a mixture of 50 g of lactic acid and 100 ml of vaseline oil. The acid converts iron metahydroxide from rust into a salt soluble in petroleum jelly - iron lactate. Wipe the cleaned surface with a cloth moistened with petroleum jelly.

Second recipe: a solution of 5 g of zinc chloride and 0.5 g of potassium hydrogen tartrate, dissolved in 100 ml of water. Zinc chloride in aqueous solution undergoes hydrolysis and creates an acidic environment. Iron metahydroxide dissolves due to the formation of soluble iron complexes with tartrate ions in an acidic environment.

Question: How to unscrew a rusty nut using improvised means?

Answer: A rusted nut can be moistened with kerosene, turpentine or oleic acid. After some time it is possible to unscrew it. If the nut “persists,” you can set fire to the kerosene or turpentine with which it was moistened. This is usually enough to separate the nut and bolt. The most radical method: apply a very heated soldering iron to the nut. The metal of the nut expands and the rust moves away from the thread; Now you can pour a few drops of kerosene, turpentine or oleic acid into the gap between the bolt and the nut. This time the nut will definitely come loose!

There is another way to remove rusty nuts and bolts. A “cup” of wax or plasticine is made around the rusted nut, the edge of which is 3-4 mm higher than the level of the nut. Dilute sulfuric acid is poured into it and a piece of zinc is placed. After a day, the nut can be easily unscrewed with a wrench. The fact is that a cup with acid and zinc metal on an iron base is a miniature galvanic cell. The acid dissolves the rust, and the resulting iron cations are reduced to the surface of the zinc. And the metal of the nut and bolt will not dissolve in the acid as long as it is in contact with zinc, since zinc is a more reactive metal than iron.

Question: What anti-rust compounds does our industry produce?

Answer: Domestic solvent-borne compounds applied “on rust” include well-known materials: primer (some manufacturers produce it under the name “Inkor”) and primer-enamel “Gramirust”. These two-part epoxy paints (base + hardener) contain corrosion inhibitors and targeted additives to cover tough rust up to 100 microns thick. The advantages of these primers: curing at room temperature, the possibility of application to a partially corroded surface, high adhesion, good physical and mechanical properties and chemical resistance, ensuring long-term operation of the coating.

Question: How can you paint old rusty metal?

Answer: For stubborn rust, it is possible to use several paints and varnishes containing rust converters:

• primer G-1, primer-paint G-2 (water-borne materials) – at temperatures up to +5°;
• primer-enamel XB-0278, primer-enamel AS-0332 – up to minus 5°;
• primer-enamel “ELOCOR SB-022” (materials based on organic solvents) – up to minus 15°C.
• Primer enamel Tikkurila Coatings, Temabond (tinted according to RAL and TVT)

Question: How to stop the rusting process of metal?

Answer: This can be done using stainless steel primer. The primer can be used both as an independent coating on steel, cast iron, aluminum, and in a coating system that includes 1 layer of primer and 2 layers of enamel. The product is also used for priming corroded surfaces.

“Nerzhamet-soil” works on the metal surface as a rust converter, binding it chemically, and the resulting polymer film reliably isolates the metal surface from atmospheric moisture. When using the composition, the total costs of repair and restoration work on repainting metal structures are reduced by 3-5 times. The primer is supplied ready for use. If necessary, it must be diluted to working viscosity with white spirit. The drug is applied to metal surfaces with remnants of tightly adhered rust and scale with a brush, roller, or spray gun. Drying time at a temperature of +20° is 24 hours.

Question: Roofing often fades. What paint can be used on galvanized roofs and gutters?

Answer: Stainless steel-cycron. The coating provides long-term protection from weather conditions, humidity, ultraviolet radiation, rain, snow, etc.

It has high hiding power and light fastness, does not fade. Significantly extends the service life of galvanized roofs. Also Tikkurila Coatings, Temadur and Temalak coatings.

Question: Can chlorinated rubber paints protect metal from rust?

Answer: These paints are made from chlorinated rubber dispersed in organic solvents. In terms of their composition, they are classified as volatile resin and have high water and chemical resistance. Therefore, it is possible to use them to protect metal and concrete surfaces, water pipes and tanks from corrosion. From Tikkuril Coatings materials, you can use the Temanil MS-Primer + Temachlor system.

Anticorrosive in the bathhouse, bathtub, pool

Question: What kind of coating can protect bath containers for cold drinking and hot wash water from corrosion?

Answer: For containers for cold drinking and washing water, we recommend paint KO-42; Epovin for hot water - compositions ZinkKOS and Teplokor PIGMA.

Question: What are enamel pipes?

Answer: In terms of chemical resistance, they are not inferior to copper, titanium and lead, and their cost is several times cheaper. The use of enameled carbon steel pipes instead of stainless steel pipes results in tenfold cost savings. The advantages of such products include greater mechanical strength, including in comparison with other types of coatings - epoxy, polyethylene, plastic, as well as higher abrasion resistance, which makes it possible to reduce the diameter of pipes without reducing their throughput.

Question: What are the features of re-enamelling bathtubs?

Answer: Enameling can be done by brush or spray with the participation of professionals, or by brushing yourself. Preliminary preparation of the bathtub surface involves removing old enamel and cleaning off rust. The whole process takes no more than 4-7 hours, another 48 hours for the bath to dry, and you can use it after 5-7 days.

Re-enamel bathtubs require special care. Such baths cannot be washed with powders such as Comet and Pemolux, or using products containing acid, such as Silit. It is unacceptable to get varnishes on the surface of the bathtub, including hair varnishes, or to use bleach when washing. Such bathtubs are usually cleaned with soap products: washing powders or dishwashing detergents applied to a sponge or soft rag.

Question: What paint materials can be used to re-enamel bathtubs?

Answer: The “Svetlana” composition includes enamel, oxalic acid, hardener, and tinting pastes. The bath is washed with water, etched with oxalic acid (stains, stones, dirt, rust are removed and a rough surface is created). Wash with washing powder. Chips are repaired in advance. Then the enamel should be applied within 25-30 minutes. When working with enamel and hardener, contact with water is not allowed. Solvent – ​​acetone. Bath consumption – 0.6 kg; drying – 24 hours. Fully gains properties after 7 days.

You can also use two-component epoxy-based paint Tikkurila “Reaflex-50”. When using glossy bathtub enamel (white, tinted), either washing powders or laundry soap are used for cleaning. Fully gains properties after 5 days. Bath consumption – 0.6 kg. Solvent – ​​technical alcohol.

B-EP-5297V is used to restore the enamel coating of bathtubs. This paint is glossy, white, tinting is possible. The coating is smooth, even, durable. Do not use “Sanitary” type abrasive powders for cleaning. Fully gains properties after 7 days. Solvents – a mixture of alcohol and acetone; R-4, No. 646.

Question: How to ensure protection against breakage of steel reinforcement in the bowl of a swimming pool?

Answer: If the condition of the pool's ring drainage is unsatisfactory, softening and suffusion of the soil is possible. Penetration of water under the bottom of the tank can cause subsidence of the soil and the formation of cracks in concrete structures. In these cases, the reinforcement in the cracks can corrode to the point of breaking.

In such difficult cases, the reconstruction of damaged reinforced concrete tank structures should include the implementation of a protective sacrificial layer of shotcrete on the surfaces of reinforced concrete structures exposed to the leaching action of water.

Obstacles to biodegradation

Question: What external conditions determine the development of wood-decaying fungi?

Answer: The most favorable conditions for the development of wood-decaying fungi are considered to be: the presence of air nutrients, sufficient wood moisture and favorable temperature. The absence of any of these conditions will retard the development of the fungus, even if it is firmly established in the wood. Most mushrooms develop well only at high relative humidity (80-95%). When wood moisture content is below 18%, the development of fungi practically does not occur.

Question: What are the main sources of moisture in wood and what is their danger?

Answer: The main sources of wood moisture in the structures of various buildings and structures include ground (underground) and surface (storm and seasonal) water. They are especially dangerous for wooden elements of open structures located in the ground (poles, piles, power line and communication supports, sleepers, etc.). Atmospheric moisture in the form of rain and snow threatens the ground part of open structures, as well as the external wooden elements of buildings. Operating moisture in liquid or vapor form in residential premises is present in the form of household moisture released during cooking, washing, drying clothes, washing floors, etc.

A large amount of moisture is introduced into a building when laying raw wood, using masonry mortars, concreting, etc. For example, 1 sq.m of laid wood with a moisture content of up to 23% releases up to 10 liters of water when it dries to 10-12%.

The wood of buildings, which dries naturally, is at risk of rotting for a long time. If chemical protection measures have not been provided, it is usually affected by house fungus to such an extent that the structures become completely unusable.

Condensation moisture that occurs on the surface or in the thickness of structures is dangerous because it is detected, as a rule, already when irreversible changes have occurred in the enclosing wooden structure or its element, for example, internal rotting.

Question: Who are the “biological” enemies of the tree?

Answer: These are mold, algae, bacteria, fungi and antimycetes (this is a cross between fungi and algae). Almost all of them can be combated with antiseptics. The exception is fungi (saprophytes), since antiseptics only affect some of their species. But it is fungi that are the cause of such widespread rot, which is the most difficult to deal with. Professionals classify rot by color (red, white, gray, yellow, green and brown). Red rot affects coniferous wood, white and yellow rot affects oak and birch, green rot affects oak barrels, as well as wooden beams and cellar floors.

Question: Are there ways to neutralize porcini mushroom?

Answer: The white house mushroom is the most dangerous enemy of wooden structures. The speed at which wood is destroyed by porcini mushroom is such that in 1 month it completely “eats” a four-centimeter oak floor. Previously, in villages, if a hut was infected by this fungus, it was immediately burned to save all other buildings from infection. After that, the whole world built a new hut for the affected family in another place. Currently, in order to get rid of white house fungus, the affected area is dismantled and burned, and the rest is impregnated with 5% chromium (5% solution of potassium dichromate in 5% sulfuric acid), while it is recommended to treat the ground with 0.5 m depth.

Question: What are ways to protect wood from rotting in the early stages of this process?

Answer: If the rotting process has already begun, it can only be stopped by thoroughly drying and ventilating wooden structures. In the early stages, disinfectant solutions, for example, such as the “Wood Healer” antiseptic compositions, can help. They are available in three different versions.

Mark 1 is intended for the prevention of wooden materials immediately after their purchase or immediately after building a house. The composition protects against fungus and wood-boring beetles.

Brand 2 is used if fungus, mold or “blue stain” has already appeared on the walls of the house. This composition destroys existing diseases and protects against their future manifestations.

Mark 3 is the most powerful antiseptic; it completely stops the rotting process. More recently, a special composition (grade 4) was developed to combat insects - “anti-bug”.

SADOLIN Bio Clean is a disinfectant for surfaces contaminated with mold, moss, and algae, based on sodium hypochlorite.

DULUX WEATHERSHIELD FUNGICIDAL WASH is a highly effective neutralizer of mold, lichen and rot. These compositions are used both indoors and outdoors, but they are effective only in the early stages of combating rot. In case of serious damage to wooden structures, it is possible to stop rotting using special methods, but this is quite complex work, usually performed by professionals using restoration chemical compounds.

Question: What protective impregnations and preservative compounds available on the domestic market prevent biocorrosion?

Answer: Of the Russian antiseptic drugs, it is necessary to mention metacid (100% dry antiseptic) or polysept (25% solution of the same substance). Such preservative compositions as “BIOSEPT”, “KSD” and “KSDA” have proven themselves well. They protect the wood from damage by mold, fungi, bacteria, and the last two, in addition, make the wood difficult to ignite. Textured coatings “AQUATEX”, “SOTEX” and “BIOX” eliminate the occurrence of fungus, mold and wood blue stains. They are breathable and have a durability of over 5 years.

A good domestic material for protecting wood is the glazing impregnation GLIMS-LecSil. This is a ready-to-use aqueous dispersion based on styrene-acrylate latex and reactive silane with modifying additives. Moreover, the composition does not contain organic solvents or plasticizers. Glazing sharply reduces the water absorption of wood, as a result of which it can even be washed, including with soap and water, protects against washing out of fireproofing impregnation, and thanks to its antiseptic properties destroys fungi and mold and prevents their further formation.

Of the imported antiseptic compositions for protecting wood, antiseptics from TIKKURILA have proven themselves well. Pinjasol Color is an antiseptic that forms a continuous water-repellent and weather-resistant coating.

Question: What are insecticides and how are they used?

Answer: To combat beetles and their larvae, toxic chemicals are used - contact and intestinal insecticides. Sodium fluoride and sodium fluoride are approved by the Ministry of Health and have been used since the beginning of the last century; When using them, safety precautions must be observed. To prevent damage to wood by the beetle, preventive treatment with silicofluoride compounds or a 7-10% solution of table salt is used. During historical periods of widespread wood construction, all wood was processed at the harvesting stage. Aniline dyes were added to the protective solution, which changed the color of the wood. In old houses you can still find red beams.

The material was prepared by L. RUDNITSKY, A. ZHUKOV, E. ABISHEV

Electrochemical protection of metal structures from corrosion is based on the imposition of a negative potential on the protected product. It demonstrates a high level of efficiency in cases where metal structures are subject to active electrochemical destruction.

1 The essence of anti-corrosion electrochemical protection

Any metal structure begins to deteriorate over time as a result of corrosion. For this reason, before use, metal surfaces are necessarily coated with special compounds consisting of various inorganic and organic elements. Such materials reliably protect the metal from oxidation (rusting) for a certain period. But after some time they need to be updated (new compounds applied).

Then, when the protective layer cannot be renewed, corrosion protection of pipelines, car bodies and other structures is carried out using electrochemical techniques. It is indispensable for protecting against rusting tanks and containers operating underground, the bottoms of sea ships, various underground communications, when the corrosion potential (it is called free) is in the zone of repassivation of the base metal of the product or its active dissolution.

The essence of electrochemical protection is that a direct electric current is connected from the outside to a metal structure, which forms cathode-type polarization of microgalvanic couple electrodes on the surface of the metal structure. As a result, the transformation of anodic regions into cathodic ones is observed on the metal surface. After such a transformation, the negative influence of the environment is perceived by the anode, and not the material itself from which the protected product is made.

Electrochemical protection can be either cathodic or anodic. With cathodic potential, the metal potential shifts to the negative side, and with anodic potential, it shifts to positive.

2 Cathodic electrical protection - how does it work?

The mechanism of the process, if you understand it, is quite simple. A metal immersed in an electrolytic solution is a system with a large number of electrons, which includes spatially separated cathode and anode zones, electrically closed to each other. This state of affairs is due to the heterogeneous electrochemical structure of metal products (for example, underground pipelines). Corrosion manifestations form on the anodic areas of the metal due to its ionization.

When a material with a high potential (negative) is added to the base metal located in the electrolyte, the formation of a common cathode is observed due to the process of polarization of the cathode and anodic zones. By high potential we mean a value that exceeds the potential of the anodic reaction. In the formed galvanic couple, a material with a low electrode potential dissolves, which leads to the suspension of corrosion (since the ions of the protected metal product cannot enter the solution).

The electric current required to protect the car body, underground tanks and pipelines, and the bottoms of ships can come from an external source, and not just from the functioning of a microgalvanic couple. In such a situation, the protected structure is connected to the “minus” of the electric current source. The anode, made of materials with a low degree of solubility, is connected to the “plus” of the system.

If the current is obtained only from galvanic couples, we speak of a process with sacrificial anodes. And when using current from an external source, we are talking about protecting pipelines, parts of vehicles and water vehicles with the help of superimposed current. The use of any of these schemes provides high-quality protection of the object from general corrosive decay and from a number of its special variants (selective, pitting, cracking, intergranular, contact types of corrosion).

3 How does the anodic technique work?

This electrochemical technique for protecting metals from corrosion is used for structures made of:

• carbon steels;
• passivating dissimilar materials;
• highly alloyed and;
• titanium alloys.

The anode scheme involves shifting the potential of the protected steel in a positive direction. Moreover, this process continues until the system enters a stable passive state. Such corrosion protection is possible in environments that are good conductors of electrical current. The advantage of the anodic technique is that it significantly slows down the rate of oxidation of the protected surfaces.

In addition, such protection can be carried out by saturating the corrosive environment with special oxidizing components (nitrates, dichromates and others). In this case, its mechanism is approximately identical to the traditional method of anodic polarization of metals. Oxidizers significantly increase the effect of the cathodic process on the steel surface, but they usually negatively affect the environment by releasing aggressive elements into it.

Anodic protection is used less frequently than cathodic protection, since many specific requirements are put forward for the protected object (for example, impeccable quality of welds of pipelines or a car body, constant presence of electrodes in the solution, etc.). In anode technology, cathodes are placed according to a strictly defined scheme, which takes into account all the features of the metal structure.

For the anodic technique, poorly soluble elements are used (cathodes are made from them) - platinum, nickel, stainless high-alloy alloys, lead, tantalum. The installation itself for such corrosion protection consists of the following components:

• protected structure;
• current source;
• cathode;
• special reference electrode.

It is allowed to use anodic protection for containers where mineral fertilizers, ammonia compounds, sulfuric acid are stored, for cylindrical installations and heat exchangers operated at chemical plants, for tanks in which chemical nickel plating is performed.

4 Features of tread protection for steel and metal

A fairly frequently used option for cathodic protection is the technology of using special protector materials. With this technique, an electronegative metal is connected to the structure. Over a given period of time, corrosion affects the protector, and not the protected object. After the protector is destroyed to a certain level, a new “defender” is installed in its place.

Protective electrochemical protection is recommended for treating objects located in soil, air, water (that is, in chemically neutral environments). Moreover, it will be effective only when there is some transition resistance between the medium and the protector material (its value varies, but in any case it is small).

In practice, protectors are used when it is economically infeasible or physically impossible to supply the required charge of electric current to an object made of steel or metal. It is worth separately noting the fact that protective materials are characterized by a certain radius over which their positive effect extends. For this reason, you should correctly calculate the distance to remove them from the metal structure.

Popular protectors:

• Magnesium. They are used in environments with a pH of 9.5–10.5 units (soil, fresh and slightly salted water). They are made from magnesium-based alloys with additional alloying with aluminum (no more than 6–7%) and zinc (up to 5%). For the environment, such protectors that protect objects from corrosion are potentially unsafe due to the fact that they can cause cracking and hydrogen embrittlement of metal products.
• Zinc. These “protectors” are indispensable for structures operating in water with a high salt content. There is no point in using them in other environments, since hydroxides and oxides appear on their surface in the form of a thick film. Zinc-based protectors contain minor (up to 0.5%) additives of iron, lead, cadmium, aluminum and some other chemical elements.
• Aluminum. They are used in sea running water and at objects located on the coastal shelf. Aluminum protectors contain magnesium (about 5%) and zinc (about 8%), as well as very small amounts of thallium, cadmium, silicon, and indium.

In addition, iron protectors are sometimes used, which are made from iron without any additives or from ordinary carbon steels.

5 How is the cathode circuit performed?

Temperature changes and ultraviolet rays cause serious damage to all external components and components of vehicles. Protecting the car body and some of its other elements from corrosion using electrochemical methods is recognized as a very effective way to prolong the ideal appearance of the car.

The principle of operation of such protection is no different from the scheme described above. When protecting a car body from rusting, the function of an anode can be performed by almost any surface that is capable of efficiently conducting electric current (wet road surfaces, metal plates, steel structures). The cathode in this case is the vehicle body itself.

Elementary methods of electrochemical protection of a car body:

1. We connect the body of the garage in which the car is parked through the mounting wire and an additional resistor to the battery positive. This protection against corrosion of the car body is especially effective in the summer, when the greenhouse effect is present in the garage. This effect precisely protects the external parts of the car from oxidation.
2. We install a special grounding metalized rubber “tail” in the rear of the vehicle so that drops of moisture fall on it while driving in rainy weather. At high humidity, a potential difference is formed between the highway and the car body, which protects the outer parts of the vehicle from oxidation.

The car body is also protected using protectors. They are mounted on the thresholds of the car, on the bottom, under the wings. The protectors in this case are small plates made of platinum, magnetite, carboxyl, graphite (anodes that do not deteriorate over time), as well as aluminum and “stainless steel” (they should be replaced every few years).

6 Nuances of anti-corrosion protection of pipelines

Pipe systems are currently protected using drainage and cathodic electrochemical techniques. When protecting pipelines from corrosion using the cathodic scheme, the following are used:

• External current sources. Their plus will be connected to the anode grounding, and the minus to the pipe itself.
• Protective anodes using current from galvanic pairs.

The cathodic technique involves the polarization of the protected steel surface. In this case, underground pipelines are connected to the “minus” of the cathodic protection complex (in fact, it is a current source). “Plus” is connected to the additional external electrode using a special cable, which is made of conductive rubber or graphite. This circuit allows you to obtain a closed-type electrical circuit, which includes the following components:

• electrode (external);
• electrolyte located in the soil where the pipelines are laid;
• pipes directly;
• cable (cathode);
• current source;
• cable (anode).

For tread protection of pipelines, materials based on aluminum, magnesium and zinc are used, the efficiency of which is 90% when using protectors based on aluminum and zinc and 50% for protectors made of magnesium alloys and pure magnesium.

For drainage protection of pipe systems, technology is used to drain stray currents into the ground. There are four options for drainage piping - polarized, earthen, reinforced and straight. With direct and polarized drainage, jumpers are placed between the “minus” of stray currents and the pipe. For the earth protection circuit, it is necessary to make grounding using additional electrodes. And with increased drainage of pipe systems, a converter is added to the circuit, which is necessary to increase the magnitude of the drainage current.