Application of corrosion protection for metals is an urgent issue for many.
Corrosion, in fact, is a spontaneous process of destruction of metals, the cause of which is the adverse effect of the environment, resulting in chemical, physical and chemical processes that lead to unfortunate consequences.
Corrosion, acting on metal, can completely destroy it. Therefore, it is necessary to deal with the emerging rust.
And not only at the moment of its appearance. It is also important preventive work to prevent the occurrence of corrosion in metals.
The following types of corrosion are distinguished by their type:
- point;
- solid;
- through;
- stains or ulcers;
- layered;
- subsurface and others.
Corrosion not only under the influence of water, but also soil, technical oil. As we see, the types of corrosion are presented widely, but the methods of protection are not so numerous.
Contents:
- Basic protection methods
- Protective anti-corrosion protection of metals
- Inhibitor
- Coating of metals
- Combination of anticorrosive methods of protection
- Protection in the factory determines SNiP
Basic protection methods
Anticorrosive methods can be grouped using the following methods:
- electrochemical method -allows to reduce the destructive process on the basis of the law of electroplating;
- reduces the aggressive reaction of the production environment;
- chemical resistance of metal;
- protects the metal surface from the adverse effects of the environment.
Surface protection and galvanic method is used already at the time of operation of metal structures and products.
These include the following methods of protection: cathodic, protector, and inhibitory.
Electrochemical protection is based on the action of an electric current, corrosion undergoes permanent corrosion damage.
Introduction of inhibitors in an aggressive environment that comes into contact with the metal, allows to reduce the rate of corrosion processes.
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Chemical resistance and surface protection relate to film storage methods. They can already be used both at the stage of manufacturing of metal products, and at the time of operation.
The following methods are distinguished: tinning, galvanizing, painting and so on. Paint, as a protective coating against rust - the most common and used method.
Protective anti-corrosion protection of metals
The basic principle that determines tread protection is the transfer of corrosion from the basic metal structure to a substitute.
That is, another metal with a negative electrical potential is attached to the protected metal. The protector, when in working condition, is destroyed and replaced by another.
Actual tread protection for structures that are in neutral environments for a long time: water, earth, soil.
Zinc, magnesium, iron, aluminum are used as a protector. A vivid example, where protector protection is used, are sea vessels constantly in the water.
Inhibitor
This agent reduces the aggressive effect of oil, acids, other chemical liquids. Used in pipelines, metal tanks.
The inhibitor has proven itself for the protection of ferrous metals, as a coating for long-term preservation of metals.
Presented as an agent that consists of boric acid with diethanolamine and vegetable oil. It is part of the diesel fuel, aviation kerosene.
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With the help of an inhibitor, metals are well protected against corrosion in media such as transformer oils, petroleum and hydrogen sulfide-containing masses.
However, the active base of this agent is insoluble in the mineral oil environment, thereby not protecting the metal from atmospheric corrosion.
Paint and varnish coating of metals
Paint is by far the most affordable and most used anti-corrosion material.
Paintwork coating creates a mechanical layer, which creates an obstacle to the impact of an aggressive environment on the metal structure or product.
The paint can be used both before the appearance of rust, and at the stage of corrosion.
In the second case, before applying the coating, the surface to be treated must be prepared: to clean the resulting corrosion damage, to seal the cracks, only after that the paint is applied, forming a protective layer.
This means protects water pipes, metal elements of residential buildings - railings, partitions.
Another plus of this protection - the paint can be different in color, therefore, the coating will serve as a decoration.
Combination of anti-corrosion protection methods
Various anti-corrosive methods of metal protection can be used together. The most commonly used paint and tread coating.
Paint, in itself, is an impractical anticorrosive material, as mechanical, water, air effects can damage its layer.
The protector will provide additional protection if the paintwork is broken.
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Modern paint can simultaneously be a protector or inhibitor. Protector protection occurs if the paint in its composition contains powdered metals: aluminum, zinc, magnesium.
The inhibitor effect is achieved if the paint contains orthophosphoric acid.
Protection in production is defined by SNiP
In the production, corrosion protection is an important point, since rust can lead not only to breakdown, but also to a catastrophe. SNiP 2.03.11 - 85 is the norm that should be applied at enterprises to prevent adverse consequences.
The conducted laboratory work allowed to describe in SNiP types of corrosion damage, sources of corrosion, as well as recommendations for ensuring the normal operation of metal structures.
In accordance with SNIP use the following protection methods:
- impregnation( sealing type) materials with increased chemical resistance;
- with adhesive film materials;
- using a variety of paint, mastic, oxide, metallized coatings.
Thus, SNiP makes it possible to apply all methods.
However, depending on where the design is located, in which environment( highly aggressive, medium, weak or completely non-aggressive), SNiP specifies the use of protective equipment, and specifies their composition.
In addition, SNiP allocates another division of media into solid, liquid, gaseous, chemical and biologically active media.
In fact SNiP for every building material: aluminum, metal, steel, reinforced concrete and others, makes its demands.
SNiP also gives advice on the use of a particular material and design, depending on the location - in water, soil, etc.
At home, unfortunately, not all methods of protection apply to metals. The main method used is to cover the product with paint.
Other methods used in production.
