What is the corrosion process

Types of corrosion

— chemical is a type of corrosion destruction associated with the interaction of a metal and a corrosive environment, in which the metal is simultaneously oxidized and the corrosive environment is restored;

- electrochemical - the process of interaction of a metal with a corrosive environment, in which the reduction of the oxidizing component of the corrosive environment does not occur simultaneously with the ionization of metal atoms and their rates depend on the electrode potential of the metal.

Types of corrosion according to conditions:

- atmospheric corrosion - the most common type of corrosion associated with the destruction of metals in the air atmosphere;

— gas — corrosive destruction of metal under the influence of gases at high temperatures;

— liquid — a type of metal corrosion in a liquid medium, which is divided into corrosion in electrolytes and non-electrolytes;

- soil - corrosion of metal in soils and soils;

- biocorrosion - a type of corrosion associated with destruction under the influence of living microorganisms;

- structural - associated with the heterogeneity of the structure of metals;

- corrosion by stray currents - a type of electrochemical destruction under the influence of stray currents;

— external current — electrochemical destruction of the metal under the influence of current from an external source;

— contact corrosion — occurs when dissimilar metals come into contact (having different stationary potentials in a given electrolyte);

— crevice corrosion is the phenomenon of increasing the rate of corrosion destruction in gaps and crevices in metal;

— stress corrosion — destruction of metal under simultaneous exposure to an aggressive environment and mechanical stress;

— cavitation — destruction of metal under simultaneous impact of the impact of the external environment and the corrosion process;

- fretting corrosion - a type of corrosion that occurs during oscillatory movements of two surfaces relative to each other in a corrosive environment;

- friction corrosion (corrosion erosion) - occurs when the metal is simultaneously exposed to friction and a corrosive environment;

Types of corrosion according to the nature of destruction:

- continuous (general corrosion) - covering the entire surface of the metal, which is under the influence of a corrosive environment;

- local - spreads only to certain areas of the metal surface.

Continuous corrosion is divided into: uniform, uneven and selective.

Local types of corrosion include: staining, pitting, pitting, through-hole, filamentous, intergranular, subsurface, knife, corrosion cracking and corrosion brittleness.

Source: https://www.okorrozii.com/vidkorrozii.html

Difference between corrosion and oxidation

Corrosion and oxidation are two different terms that express the same idea. The oxidation reaction is one of two simultaneous redox reactions. Corrosion is a type of oxidation.

Corrosion occurs when metal atoms on the surface of a metal become oxidized in the presence of oxygen and water. Corrosion in iron or steel can be recognized as rust. There are methods to prevent metals from rusting.

The main difference between corrosion and oxidation is that corrosion occurs primarily on metal surfaces, whereas oxidation can occur anywhere.

Key areas covered

1. What is corrosion
- definition, explanation of the process, prevention
2. What is oxidation
- definition, explanation
3. What is the relationship between corrosion and oxidation
4. What is the difference between corrosion and oxidation
- Comparison of the main differences

Key words: corrosion, electroplating, galvanization, humidity, metal, metal alloy, metal oxidation, oxidation, redox reaction, rusting

What is corrosion

Corrosion is the destruction of a material due to various reactions that occur on its surface when the material is exposed to the environment. This occurs due to chemical reactions that occur between the surface of the material and components in the air.

Corrosion can occur on both metallic and non-metallic surfaces. Corrosion of a material affects the surface structure of the material. The most common example of corrosion is rust. Here the color and quality of the steel changes. This is caused by a chemical reaction between the surface of the metal and the moisture and oxygen in the air. Therefore, to protect the metal from corrosion, different grades of steel were made by changing the chemical composition of the metal alloy.

Corrosion can also occur on non-metallic surfaces such as countertops and leather. When certain harsh chemicals fall on these surfaces, deterioration of that surface can occur. Such chemicals include strong acids and strong bases.

Corrosion on metals is also known as metal oxidation . This is because metal atoms on the surface are oxidized by oxygen in the air in the presence of water. For example, Fe+2 in steel can be oxidized to Fe+3 during iron corrosion. The rate of corrosion depends on several factors such as air humidity, metal surface area that is exposed to air, etc.

Figure 1: Iron Corrosion

There are several methods to prevent metal corrosion. Some of these strategies are listed below.

• Environmental modifications
• Galvanization - Zinc coating can prevent iron from rusting by acting as a sacrificial anode.
• Corrosion inhibitors are chemicals that can avoid corrosion by interrupting the oxidation reaction on the metal surface.
• Paints. Coating with paints avoids corrosion.
• Electroplating is a process where a thin layer of metal (eg nickel, chromium) is applied to the surface of steel.

Corrosion affects the microstructure of the metal by changing the chemical composition; this affects the mechanical properties and appearance of the metal.

What is oxidation

Oxidation is the loss of electrons during the reaction of a molecule, atom, or ion. Since atoms are made up of equal numbers of protons and electrons, when they are neutral, the loss of electrons gives the atoms a positive charge. The oxidation state is given as the oxidation state. When an atom undergoes oxidation, the oxidation number of that atom increases positively. The opposite of oxidation is reduction.

There is always a reduction reaction occurring in parallel with oxidation. In other words, oxidation and reduction reactions occur simultaneously. These two reactions are called redox reactions. One reaction alone is called a half reaction . The oxidation reaction releases electrons, which are then used up in the reduction reaction.

Figure 2: Magnesium Oxidation

In the past, oxidation referred to the addition of molecular oxygen to a compound. But this definition cannot explain the oxidation reactions that occur in the absence of molecular oxygen. Compounds that can cause other compounds to oxidize are known as oxidizing agents. The species that can oxidize is called a reducing agent.

Relationship between corrosion and oxidation

• Oxidation is the loss of electrons during the reaction of a molecule, atom, or ion.
• Corrosion occurs when metal atoms on a surface undergo oxidation.

Definition

Corrosion: Corrosion is the destruction of a material due to various reactions that occur on its surface when the material is exposed to the environment.

Oxidation: Oxidation is the loss of electrons during the reaction of a molecule, atom or ion.

Benefits

Corrosion: Corrosion is often not a beneficial process.

Oxidation: Oxidation reactions are very useful in various laboratory settings.

Process

Corrosion: Corrosion is an irreversible process.

Oxidation: Oxidation is the reaction half of redox reactions.

oxygen

Corrosion: Corrosion occurs in the presence of oxygen.

Oxidation: Oxidation can occur in the absence or presence of oxygen.

Conclusion

Corrosion is the wear and tear of metallic or non-metallic surfaces. We can recognize the corrosion of metal surfaces. Oxidation reactions always occur simultaneously with a reduction reaction. Oxidation is the loss of electrons from atoms, molecules or ions. The main difference between corrosion and oxidation is that corrosion occurs primarily on metal surfaces, whereas oxidation can occur anywhere.

Recommendations:

1. Bell, Terence. “How and why do metals corrode?” Balance,

Source: https://ru.strephonsays.com/difference-between-corrosion-and-oxidation

3 ways to preserve a car body that has begun to rust - Krasnodar MVL - auto blog

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Rust is a nightmare for motorists. Sooner or later this appears on every machine. It is for this reason that every responsible driver tries with all his might to delay the inevitable.

However, you need to know not only how to protect the body, but also what to do when the worst has already happened to the car. There are currently three main ways to combat rust.

1. Small rust spots

Scratches are the places where, in the vast majority of cases, the “victorious” effect of rust on the car body begins. If you notice the corrosion process in time and take appropriate measures, you can save yourself from a huge number of headaches and, most importantly, from large-scale donations for subsequent repairs.

Removing small rust stains is not difficult at all. To do this, the “sick” part of the body is cleaned with several types of sandpaper and then galvanized. Then prime the area, paint and varnish.

2. Large spots of corrosion

In such a situation, it is strongly recommended to seek help from a specialist. However, if the garage (of a friend, neighbor, colleague) has the necessary tools, and the driver himself has the necessary skills, then the problem can still be solved independently. The area of ​​corrosion will need to be “cured” with greater force and in a more complex manner.

First, the problem area is cleaned with a wire brush. It is then polished using an abrasive disc (this will remove any existing paint bubbles). After this, the surface is cleaned with various types of sandpaper.

When the rust is completely removed, galvanize the area, apply a primer to it, then paint and cover with a protective layer of varnish.

3. Severe corrosion with holes

If rusty holes appear on the car body, then this is very bad. Getting out of this situation is not only difficult, but also very expensive. In addition, even investing a lot of money into repairs does not guarantee a positive effect (especially over a long time). The most important thing in this case is that dealing with a rotten place only on your own, without the help of a specialist, will definitely not work.

To a greater or lesser extent, this problem is effectively “treated” in only one way - amputation. And it's not a joke. The damaged part of the housing must be completely cut. The new metal sheet is welded in place. Only after this the putty is applied and after that all other cosmetic procedures are performed.

Source: https://krasnodarmvl.ru/2020/01/19/3-sposoba-sohranit-korpus-avtomobilja-kotoryj-nachal-rzhavet/

What is Corrosion

Corrosion - 1. Destruction of solids under the influence of various physical and chemical processes.
2. transfer Negative changes in the political, economic, moral life of society and people.

The meaning of the word Corrosion according to Ozhegov:

Corrosion - Destruction, erosion of solids caused by chemical and electrochemical processes

Corrosion in the Encyclopedic Dictionary:

Corrosion - (from Late Latin corrosio - corrosion) - destruction of solids caused by chemical and electrochemical processes developing on the surface of the body during its interaction with the external environment. Corrosion causes particular damage to the national economy . A common type is rusting of iron (see also Rust). As a result of corrosion, approx.

10% of the total amount of ferrous metals smelted. Can be reduced or virtually eliminated by applying protective coatings, e.g. paint and varnish. introduction of inhibitors into the environment, for example. chromates, nitrites, arsenites. the use of corrosion-resistant materials. Concrete, building stone, wood, and other materials are also subject to corrosion destruction.

Corrosion of polymers is called degradation.

in geology -..1) dissolution of rocks on the surface of the Earth under the influence of the chemical action of water (for example, the phenomenon of karst) 2) corrosion, partial dissolution and melting by magma of previously released minerals or captured rock fragments.

The meaning of the word Corrosion according to the Construction Dictionary:

Corrosion - The process of destruction of a material as a result of chemical or physical influence. There are electrochemical, chemical and biological corrosion.

The meaning of the word Corrosion according to Ushakov’s dictionary:

CORROSION
corrosion, pl. no, w. (Latin: corrosio). 1. Destruction of rocks under the influence of water (geol.). 2. Corrosion of metals by acids (chemical). Rust is the simplest type of corrosion.

The meaning of the word Corrosion according to the Brockhaus and Efron dictionary:

Corrosion (geol.) - a change produced by fiery liquid magma in porphyritic secretions of lavas and porphyry rocks. These secretions (such as quartz crystals, etc.) are in this case corroded, “corroded”.

Definition of the word “Corrosion” according to TSB:

Corrosion - Corrosion (from Late Lat. corrosio - corrosion) (geological),

1) destruction (dissolution) of rocks under the influence of the chemical action of water with the formation of cracks, channels, funnels, basins, caverns, caves and other voids and depressions. It is especially clearly manifested in places of development of easily soluble rocks (rock salt (See Rock salt), gypsum, limestone, etc.). see Karst.

2) Corrosion and partial dissolution by magmatic melt or lava of phenocryst crystals released at the first stage of their crystallization, or rock fragments (Xenoliths) captured by magma during its intrusion.

Source: https://xn----7sbbh7akdldfh0ai3n.xn--p1ai/korroziya.html

Metal corrosion - causes and methods of protection

The phrase “metal corrosion” contains much more than the name of a popular rock band. Corrosion irreversibly destroys metal, turning it into dust: of all the iron produced in the world, 10% will be completely destroyed in the same year. The situation with Russian metal looks something like this: all the metal smelted in a year in every sixth blast furnace in our country becomes rusty dust before the end of the year.

The expression “costs a pretty penny” in relation to metal corrosion is more than true - the annual damage caused by corrosion is at least 4% of the annual income of any developed country, and in Russia the amount of damage is ten figures. So what causes corrosion processes in metals and how to deal with them?

What is metal corrosion

Destruction of metals as a result of electrochemical (dissolution in a moisture-containing air or aqueous medium - electrolyte) or chemical (formation of metal compounds with highly aggressive chemical agents) interaction with the external environment. The corrosion process in metals can develop only in some areas of the surface (local corrosion), cover the entire surface (uniform corrosion), or destroy the metal along grain boundaries (intercrystalline corrosion).

Metal under the influence of oxygen and water becomes a loose light brown powder, better known as rust (Fe2O3 H2O).

Chemical corrosion

This process occurs in environments that are not conductors of electric current (dry gases, organic liquids - petroleum products, alcohols, etc.), and the intensity of corrosion increases with increasing temperature - as a result, an oxide film is formed on the surface of metals.

Absolutely all metals, both ferrous and non-ferrous, are susceptible to chemical corrosion. Active non-ferrous metals (for example, aluminum) under the influence of corrosion are covered with an oxide film, which prevents deep oxidation and protects the metal.

And such a low-active metal as copper, under the influence of air moisture, acquires a greenish coating - patina.

Moreover, the oxide film does not protect the metal from corrosion in all cases - only if the crystal-chemical structure of the resulting film is consistent with the structure of the metal, otherwise the film will not help in any way.

Alloys are subject to another type of corrosion: some elements of the alloys are not oxidized, but are reduced (for example, in a combination of high temperature and pressure in steels, carbides are reduced by hydrogen), and the alloys completely lose the necessary characteristics.

Electrochemical corrosion

The process of electrochemical corrosion does not necessarily require immersing the metal in an electrolyte - a thin electrolytic film on its surface is sufficient (often electrolytic solutions permeate the environment surrounding the metal (concrete, soil, etc.)).

The most common cause of electrochemical corrosion is the widespread use of household and industrial salts (sodium and potassium chlorides) to remove ice and snow on roads in winter - cars and underground communications are especially affected (according to statistics, annual losses in the USA from the use of salts in winter are 2.5 billion dollars).

The following happens: metals (alloys) lose some of their atoms (they pass into the electrolytic solution in the form of ions), electrons replacing the lost atoms charge the metal with a negative charge, while the electrolyte has a positive charge. A galvanic couple is formed: the metal is destroyed, gradually all its particles become part of the solution.

Electrochemical corrosion can be caused by stray currents that occur when part of the current leaks from an electrical circuit into aqueous solutions or into the soil and from there into a metal structure. In those places where stray currents exit metal structures back into water or soil, metal destruction occurs. Stray currents occur especially often in places where ground electric transport moves (for example, trams and electric railway locomotives).

In just one year, stray currents with a force of 1A are capable of dissolving 9.1 kg of iron, 10.7 kg of zinc, and 33.4 kg of lead.

Other causes of metal corrosion

The development of corrosion processes is facilitated by radiation and waste products of microorganisms and bacteria. Corrosion caused by marine microorganisms causes damage to the bottoms of seagoing vessels, and corrosion processes caused by bacteria even have their own name - biocorrosion.

The combination of the effects of mechanical stress and the external environment greatly accelerates the corrosion of metals - their thermal stability decreases, surface oxide films are damaged, and in those places where inhomogeneities and cracks appear, electrochemical corrosion is activated.

Measures to protect metals from corrosion

An inevitable consequence of technological progress is the pollution of our environment - a process that accelerates the corrosion of metals, as the external environment shows them more and more aggression. There are no ways to completely eliminate the corrosive destruction of metals; all that can be done is to slow down this process as much as possible.

To minimize the destruction of metals, you can do the following: reduce the aggression of the environment surrounding the metal product; increase metal resistance to corrosion; eliminate interaction between the metal and substances from the external environment that exhibit aggression.

Over thousands of years, mankind has tried many methods of protecting metal products from chemical corrosion, some of them are still used today: coating with fat or oil, other metals that corrode to a lesser extent (the most ancient method, which is more than 2 thousand years old, is tinning (coating tin)).

Anti-corrosion protection with non-metallic coatings

Non-metallic coatings - paints (alkyd, oil and enamels), varnishes (synthetic, bitumen and tar) and polymers form a protective film on the surface of metals, excluding (while intact) contact with the external environment and moisture.

The advantage of using paints and varnishes is that these protective coatings can be applied directly at the installation and construction site. The methods for applying paints and varnishes are simple and amenable to mechanization; damaged coatings can be restored “on the spot” - during operation; these materials have a relatively low cost and their consumption per unit area is small.

However, their effectiveness depends on compliance with several conditions: compliance with the climatic conditions in which the metal structure will be operated; the need to use exclusively high-quality paints and varnishes; strict adherence to the technology of application to metal surfaces.

It is best to apply paints and varnishes in several layers - their quantity will provide better protection against weathering on the metal surface.

Polymers - epoxy resins and polystyrene, polyvinyl chloride and polyethylene - can act as protective coatings against corrosion. In construction work, reinforced concrete embedded parts are coated with coatings made from a mixture of cement and perchlorovinyl, cement and polystyrene.

Protection of iron from corrosion by coatings of other metals

There are two types of metal inhibitor coatings - protective (zinc, aluminum and cadmium coatings) and corrosion-resistant (silver, copper, nickel, chromium and lead coatings).

Inhibitors are applied chemically: the first group of metals has greater electronegativity with respect to iron, the second has greater electropositivity.

The most widespread in our everyday life are metal coatings of iron with tin (tinplate, cans are made from it) and zinc (galvanized iron - roofing), obtained by pulling sheet iron through a melt of one of these metals.

Cast iron and steel fittings, as well as water pipes, are often galvanized - this operation significantly increases their resistance to corrosion, but only in cold water (when hot water is supplied, galvanized pipes wear out faster than non-galvanized ones).

Despite the effectiveness of galvanizing, it does not provide ideal protection - the zinc coating often contains cracks, the elimination of which requires preliminary nickel plating of metal surfaces (nickel plating).

Zinc coatings do not allow paint and varnish materials to be applied to them - there is no stable coating.

The best solution for anti-corrosion protection is aluminum coating. This metal has a lower specific gravity, which means it consumes less, aluminized surfaces can be painted and the paint layer will be stable. In addition, aluminum coating is more resistant to aggressive environments than galvanized coating.

Aluminizing is not very common due to the difficulty of applying this coating to a metal sheet - aluminum in the molten state is highly aggressive towards other metals (for this reason, molten aluminum cannot be kept in a steel bath). Perhaps this problem will be completely solved in the very near future - an original method of performing aluminization has been found by Russian scientists.

The essence of the development is not to immerse the steel sheet in molten aluminum, but to raise liquid aluminum to the steel sheet.

Increasing corrosion resistance by adding alloying additives to steel alloys

The introduction of chromium, titanium, manganese, nickel and copper into the steel alloy makes it possible to obtain alloy steel with high anti-corrosion properties. The steel alloy is given special resistance by its large proportion of chromium, due to which a high-density oxide film is formed on the surface of structures.

The introduction of copper into the composition of low-alloy and carbon steels (from 0.2% to 0.5%) makes it possible to increase their corrosion resistance by 1.5-2 times.

Alloying additives are introduced into the steel composition in compliance with Tamman's rule: high corrosion resistance is achieved when there is one atom of alloying metal for every eight iron atoms.

Measures to counteract electrochemical corrosion

To reduce it, it is necessary to reduce the corrosive activity of the environment by introducing non-metallic inhibitors and reducing the number of components that can start an electrochemical reaction. This method will reduce the acidity of soils and aqueous solutions in contact with metals.

To reduce corrosion of iron (its alloys), as well as brass, copper, lead and zinc, it is necessary to remove carbon dioxide and oxygen from aqueous solutions. The electrical power industry removes chlorides from water that can affect localized corrosion.

By liming the soil you can reduce its acidity.

Stray current protection

It is possible to reduce electrical corrosion of underground communications and buried metal structures by following several rules:

• the section of the structure serving as a source of stray current must be connected with a metal conductor to the tram rail;
• heating network routes should be located at the maximum distance from the rail roads along which electric vehicles travel, minimizing the number of their intersections;
• the use of electrically insulating pipe supports to increase the transition resistance between the soil and pipelines;
• at inputs to objects (potential sources of stray currents), it is necessary to install insulating flanges;
• install conductive longitudinal jumpers on flange fittings and gland expansion joints to increase longitudinal electrical conductivity on the protected section of pipelines;
• In order to equalize the potentials of pipelines located in parallel, it is necessary to install transverse electrical jumpers in adjacent areas.

Protection of metal objects equipped with insulation, as well as small steel structures, is carried out using a protector that functions as an anode. The material for the protector is one of the active metals (zinc, magnesium, aluminum and their alloys) - it takes on most of the electrochemical corrosion, breaking down and preserving the main structure. One magnesium anode, for example, protects 8 km of pipeline.

Source: https://dvamolotka.ru/post/10066-korroziya-metalla-prichiny-vozniknoveniya-i-metody-zaschity

Car roof rails: what are they and what are they for?

Often, modern passenger cars do not have a large luggage compartment or its size is not enough in certain situations. In this case, roof rails come to the rescue; they are installed on the roof and serve as an additional trunk for transporting large items, as well as a place for installing closed boxes.

What are car roof rails?

Physically, roof rails are arches of a certain diameter and length that are installed on the roof of the car. They can be supplied as standard for the following body types:

• SUV;
• crossover:
• pickup;
• minivan and minibus;
• station wagon

Car roof rails

For other types of bodywork, certain places are provided for the installation of transverse or longitudinal rails. Most often, these are technological holes in the roof for the original element, which are closed with plastic plugs. In this case, the driver needs to buy car roof rails separately and attach them himself.

VAZ cars before 2012 are not equipped with standard roof rails; installation of fasteners for luggage bars is carried out independently. Drivers need to drill into metal to install the rack.

What are they needed for

The roof rails on the car play the role of a load-bearing element on which an additional luggage rack is installed. The latter can be:

• frame structure made of open longitudinal or transverse plates;
• closed car box,
• trunk in the form of a loading area;
• special cross mount for bicycles;
• open basket.

If you install integrated rails, you can pack the things necessary for transportation without installing crossbars, for example, when transporting building materials or large items.

Roof rails Kia Sportage

Types of roof rails

Roof rails are classified:

• according to the material of manufacture;
• design;
• by type of installation.

For the manufacture of roof rails, steel, plastic and metal-plastic are used. Steel structures are installed to transport heavy loads. They provide grip rigidity and reliable transportation. Universal types of roof rails can be mounted on any car of suitable dimensions.

Model designs are designed for installation on a specific make of car, often for a specific year of manufacture. For example, the Nissan X-Trail after 2015 is equipped with standard model roof rails with an additional headlight, which are not suitable for installation on other models of this class.

Plastic elements are equipped with crossbars. The peculiarity of this type of trunk is that it is easy to remove. Plastic arches are installed under closed car boxes; the design of the trunk allows you to evenly distribute the weight of the luggage.

Design

Before installing the rails, determine the diameter, length and design of the structure. By type, arcs are divided into:

• rectangular;
• aerodynamic.

A rectangular railing is a metal or steel profile covered with a plastic casing. The rectangular profile has a simple design, it is easy to remove, installation is carried out with bolts or special fasteners.

Rectangular roof rails

The disadvantage of the standard bar is that the trunk makes noise at speeds above 80 km/h, and there is excessive fuel consumption due to poor aerodynamic performance.

Aerodynamic integrated roof rails are made of anodized aluminum and weigh up to 3 kg. They do not create additional aerodynamic drag and do not create noise at speeds above 80 km/h. Installation of the structure - on fastening sleeves.

Classification by installation method

Installation of roof rails depends on the specific model of the trunk. The most common classification remains:

• longitudinal;
• transverse arcs.

Longitudinal rails are installed on the roof in the drainage area. Transverse rods are attached to the arches. What are these roof rails needed for? - for transporting large-sized, non-standard cargo. The rods are attached to the longitudinal arches through locking fasteners. Depending on the size of the roof and the transportation option, you can remove the middle bar or install an additional one by selecting the desired distance between the crossbars.

Transverse structures are two- and three-support arches that are mounted across the roof. For station wagons and liftbacks, the installation of four transverse arches or longitudinal integrated roof rails is provided.

Integrated roof rails are an arc, after installation of which there is no free space left between the roof and the element. The arches are most often installed at the factory; they have only a model version and are not intended for reinstallation on other brands of cars.

The rack is designed for installation on a flat roof. The kit includes an integrated lock or fastener that is mounted in the doorway.

Installation features

Installation of roof rails can be carried out:

• in standard places on the roof of the car;
• into the doorway after preparing the body.

Integrated roof rails are installed only in standard places. The original arches have special stops that are installed in holes on the roof. The set of original roof rails includes adapters that are designed for a specific model.

Installation of roof rails

If the car model does not have places provided for standard roof rails, drivers either use sets of arches for installation on the doorway, or drill technological holes in the roof for fasteners.

Rails for flat roofs have a large area of ​​supporting arches. During installation, it is necessary to carry out anti-corrosion treatment, since the corrosion process may begin where the bolts enter the metal of the body.

Important points

You can install the additional trunk yourself with a minimum of tools. Important installation features:

1. Remove the plugs for the standard holes for the trunk according to the marks on the parts.
2. Clean the seat under the railing, degrease it, and treat it with silicone sealant. This will prevent corrosion and moisture from penetrating under the roof metal.
3. Install the required type of railing according to the instructions.

Tips for choosing roof rails for a car

When installing an additional roof rack, it is necessary to take into account the main requirements when choosing roof rails. Tips before purchasing:

1. Determine what type of roof rails, longitudinal or transverse, is provided by the manufacturer for the car. For SUVs and pickups, both transverse and longitudinal are offered, for other classes - only longitudinal.
2. If the factory does not provide places for attaching the luggage bar, choose only transverse structures that are suitable in length.
3. Take into account the load on the railing. Plastic arches can withstand weight up to 40 kg, aluminum – up to 60 kg, steel – up to 90 kg.
4. When choosing universal types of roof rails that can be installed on cars of various classes, the size of the roof and the number of fasteners on the arch are taken into account. Manufacturers indicate in the trunk passport the compatibility of the roof rail with a certain class of car.

Many drivers have already appreciated the convenience and usefulness of roof rails. Quite often, the trunk is not removed after use, rightly believing that the minimum weight and the absence of aerodynamic load do not affect the dynamics of the car and improve its appearance.

Source: https://techautoport.ru/nesuschaya-sistema/dopolnitelnoe-osnaschenie/reylingi.html

Classification of types of corrosion and methods of protection against it

Corrosion is a dangerous process of degradation (i.e. destruction) of the top layer of metals under the influence of various environments. Corrosion is usually caused by the chemical environment that surrounds the metal.

Regardless of the type of structure and its operation, the simplest and most understandable method for combating this phenomenon is to “protect against corrosion” using protective paints and special varnishes.

Main types of corrosion

Speaking about the mechanism of the corrosion process, we can notice 2 main types of corrosion: chemical and electrochemical.

Chemical is a clear result of the passage of reactions during which, after the destruction of the metal bond, parts of the metal and all the atoms that are included in the oxidizing agents create a strong bond. An electric current cannot occur between different parts of a metal surface. This type of corrosion may be inherent in chemical media that are not able to transmit electric current. This includes gases and non-electrolytes.

It is important to remember that the cause of corrosion also affects the rate of corrosion. Electrochemical corrosion is a process of degradation of metals. This process occurs along with the emergence of electricity in the system.

Classification of corrosion according to the significance of the process itself

Bridge arch, with more severe rust in places where the paint layer has been destroyed

Corrosion processes can be divided:

• by the type of mutual influence of metals with the surrounding atmosphere;
• by the type of corrosive atmosphere and the conditions of the process itself;
• according to the characteristics of degenerative effects;
• The “corrosion rate” is greatly influenced by the type of surrounding atmosphere.

Types of corrosion and process description

• Chemical is a type of mutual influence of a metal with the environment, during which the oxidation and further reduction of part of the environment occur in a single act. Products of mutual influence have no separation in space.
• Electrochemical is a type of mutual influence of a metal with a corrosive space in which the ionization reaction of the corrosive environment takes place in several acts.
• Gas— This is corrosion of metal surfaces with low water content (usually no more than 0.2% moisture) or at maximum operating temperatures.

  In the modern chemical and gas industry, this type of corrosion can occur more often than others.

• Atmospheric is a type of corrosion in an air atmosphere or in a humid gas environment.
• Biocorrosion is a biological type of metal corrosion that occurs under the influence of the vital activity of microbes and various microorganisms.

• Contact corrosion is a type of corrosion that is provoked by the contact of several types of metals with different stationary potentials.
• Radiation is a type of metal corrosion that is caused by the influence of radioactive radiation.

Corrosion by external or stray electric current also exists.

Another type of corrosion is stress corrosion, which is provoked by the simultaneous influence of a corrosive environment and the flow of mechanical stress. It is important to consider that this type of corrosion is very harmful, especially for systems subject to severe physical stress.

Features of anti-corrosion compounds

Rust is visible in places where the paint is chipped, but there is no corrosion on the axles covered with lubricant

What are corrosion inhibitors? These are substances and elements that, when present in an environment subject to the dangerous influence of corrosion, are able to reduce and generally stop the corrosive effect on the metal. A corrosion inhibitor can be either a single chemical compound or a mixture of many.

Inhibitors are most often surfactants, as well as all kinds of organics.
When affecting the product, they further improve the protective characteristics of the oxide film on the metal. For this reason, you can conclude that the presence of oxygen in the environment favors an increase in the protective effect against corrosion. However, if the oxide film has poor stability, the adsorption of the inhibitor on the top layer of metal worsens.

• Scale inhibitor IOMS-1 (solution) g 200 rub/kg. Macroflex.
• Corrosion inhibitor Protectogen (protectogen). C Aqua.
• Complexonate is a solution of a zinc complex. Ectoscale.
• GALAN. Tread. Corrosion inhibitor (5 l). Protects pipelines, radiators and other heating systems from corrosion.

Copper corrosion

Copper corrosion is its destruction under the influence of the environment. Copper in varying concentrations in other metals is widely used in many industries around the world. Copper is used in construction due to the maximum corrosion resistance of this metal and its high degree of thermal conductivity.

Iron corrosion

The oxidation reaction during iron corrosion occurs by the passage of electrons to the oxidizing agent. The corrosion product of this type of metal is rust. In practice, you can see rust with a fairly diverse range of shades - from dark red to light orange, or almost black.

Effect of corrosion on aluminum

Corrosion of aluminum occurs in many environments and may only persist in cases where a protective coating has formed on the top of the metal.

It is important to remember that alkalis can quickly dissolve the protective film of aluminum, which begins its reaction with water. As a result, the metal usually dissolves in the environment, releasing a large amount of hydrogen. This is how “corrosion of aluminum and its alloys” occurs in nature.

Ways to protect metal from corrosion

Anti-corrosion protection can be carried out using the following methods:

• Increasing the overall corrosion resistance of a metal by changing its chemical properties. structures;
• Insulation of the metal surface using special coatings can also be used;
• Reducing the aggressiveness of the place where the metal is used;
• The use of currents that increase resistance to the effects of corrosion.

Protective compounds are quite easy to use, inexpensive and quickly updated if desired, and also create a more decorative appearance for a metal product.

Protection against corrosion is determined by the physical insulation of the metal, or the powerful electrical-chemical effect of the anti-corrosion coating on the surface. The main disadvantages of most paints and varnishes are their poor water permeability and sometimes poor temperature stability.

Protective film as a barrier to destruction

Coating the top of the metal with a special paint layer serves as an excellent barrier to the formation of corrosion, and therefore can reduce the spread of corrosion. Of particular importance in this matter is the quality of the coating (anti-corrosion paint is used) - the thickness of the paint layer and its porosity are taken into account.

Also, the quality of the metal coating will depend on the level of surface preparation and the method of working with the anti-corrosion coating. Any rust must be cleaned off.

Anti-corrosion paints and varnishes

Anti-corrosion paint for metal is a substance that protects metal from exposure to a hazardous external environment.

• The composition is lubricated on the damaged surface.
• This material creates a more weather-resistant coating.
• Maximum resistance to rust.

Rust paint can also be used. Rust-resistant paint, when applied to metal in a timely and correct manner, guarantees long-term protection of pipelines and metal systems. This paint can protect elements of mechanisms and industrial devices, as well as machine parts from the harmful effects of rust. The paint is used to treat technological systems and other equipment, including hydraulic mechanisms and bridges.

• Elakor-PU - enamels for processing metal parts and paint for metal.
• Thick-layer anti-corrosion coating based on alkyd resins. FEIDAL Coatings.
• Enamel PF, PF 115 and enamel PF-1189. "Sigma paints"
• Anti-corrosion paint NOR-MAALI. Used as a surface paint. Manufacturer CARBOLINE - Norway. The line of Nor-Maali paints is quite wide - about a hundred types. They are mainly used for industrial purposes: shipbuilding, bridge building, construction

However, not every paint can guarantee the best protection. It is worth considering the types of anti-corrosion enamels. Specialists use paints and varnishes to reduce the cost of work. In addition, this product speeds up the coating process.

Source: https://accorel.ru/tsvetnaya-zhizn/klassifikatsiya-vidov-korrozii-i-sposoby-zashhity-ot-nee