Develop effective methods of monuments PROTECTION AGAINST CORROSION
In Intarsia Ltd. have developed an effective method of protection against atmospheric corrosion of a metal surface. This technology is particularly ideal for the protection of metal monuments and monumental buildings, but may be applicable to other purposes, such as protective coatings for cars.
In an atmosphere of modern cities, especially large, aggressive media content has increased significantly. Therefore, the surface of the monument, made of metal, are ever-increasing atmospheric corrosion. Existing methods for protecting metal monuments are no longer effective enough and are not able to provide the required degree of long-term protection against corrosion, the nature of which has recently changed significantly. It is known that in non-industrial atmosphere (for example, in rural areas) on the surfaces of monuments made of copper alloys for 80-120 years, slowly growing so-called benign patina, and the process of its formation stops.
In modern large-scale urban atmosphere on the surface of copper alloy is formed by wild or malignant, patina, which does not form a dense layer and loose fibers fractured, allowing contact of the metal with the atmosphere, whereby the process of destruction of the metal continues.
Furthermore, there has often been such types of corrosion as bronze disease (swine or copper), which produce basic copper chloride - run cyclic chain reactions involving copper, oxygen and moisture of the atmosphere, resulting in a continuous intensive corrosion breaking surface authoring . And with frequent perepatinirovaniyah in reaction formation of a new patina involved more and more copper from the original surface, which leads to more and more of its smoothing, that is, to an increasing distortion of the author#39;s relief.
Existing substances, so-called corrosion inhibitors, which should, in principle hinder its development, the reality does not have the desired effect. And all because they are quickly washed off the surface of the metal monuments water precipitation, are destroyed by ultraviolet radiation and other factors caused by the influence of the environment.
Therefore, one of the remaining two efficient methods of protecting metal surfaces against corrosion is the process applied to these metallic coatings or layers, referred to as sacrificial. This layer protects the surface of the monument, isolating it from the weather, with very corroded and eventually destroyed. Such coatings can be applied in various ways, for example electroforming.
But still another problem remained unsolved v how to apply this method of application in the case of large sites?
Another efficient method of applying a protective metal layer can effectively handle large objects, is sprayed metal powder, e.g., by plasma or flame spraying. However, in the coating obtained by spraying coating of the structure is more or less porous.
A porosity of the protective layer is a deficiency that must be addressed. Porosity does not allow obtaining a coating having sufficient barrier properties, since this coating does not prevent the contact with aggressive media object to be protected, and moreover, due to the presence of pores has a high specific surface area and relatively quickly destroyed.
A new way to protect the metal surface sites, from the effects of atmospheric corrosion, providing a more reliable and long-lasting protection, developed in Intarsia LLC.
Their technique relies on the fact that during the deposition of the protected metal surface of the metal powder in the form of a thin porous layer, a porous layer of sprayed powder is impregnated with a special corrosion inhibitor sprayed metal.
If this is the porosity of the deposited layer itself is not used as a drawback, but as a positive factor, which allows to keep the corrosion inhibitor. Inhibitor, getting into the pores of the layer is securely held therein, which prevents the impact of atmospheric factors through the pores of the metal and increases the durability of the coating as an inhibitor because of its inhibitory properties, prevents heavy metal monument and destruction of the coating material, reducing the rate of destruction of multiple layer coating. The amount of inhibitor, such a layer retained by several orders of magnitude greater than that which can be deposited on the surface of the layer without the monument.
As a result, protects metal surfaces, in particular, the surface of the monument, a much longer it will resist atmospheric corrosion and service life of the protected products to increase. A method for coating the surface of the monument to the rise and mezhrestavratsionny period.
The thickness of the deposited layer may be from powder of a micron to several hundred microns, such as from 0.1 microns to 900 microns, but the recommended developer - from 20 to 200 microns, with the optimum of about 50 microns. The thickness of the layer depends on the size of the object (the monument) and the author#39;s plastic surface. The smaller the monument and the more subtle details of the image are, the smaller is the permissible thickness of the layer, and vice versa. Particle size of powder, of course, should not exceed the thickness of the layer.
The particles of powder have dimensions of not more than half the thickness of the layer, in particular not more than 25 microns for powder coating layer thickness of about 50 microns.
At inhibitor impregnated evaporated easily applied powder layer additional material providing barrier protection, for example a polymer coating. Under a layer of barrier protection is meant a continuous layer of material impervious to weather and insulating them from the protected object. This barrier layer provides added protection of the object and an additional increase in protective coating durability.
The porous surface of the deposited layer is very well keeps barrier method of protection (eg, polymer coating) applied to its surface.
Notably, spraying of the powder of the protective layer can be carried out in any known manner allowing to apply the desired thickness of the powder layer with the desired adhesion, or the entire surface at desired locations. It is usually necessary to apply a uniform thickness layer of powder over the entire surface, but the thickness of the deposited layer and can also vary. Spraying can be done, for example, by means of devices such as plasma torches, gas-flame burner, arc Metallizator and detonation-gas guns.
During the test the plates of copper, copper-tin bronze and steel protective layers were applied by new technology. Test plates covered by traditional methods of protection against corrosion. Then all the plates were subjected to cyclic ultraviolet light, positive and negative variable temperatures, irrigation sulfurous acid, cyclic test of sulfur dioxide, salt fog, and other factors over time equivalent to a particularly hard (GOST) to the atmosphere of industrial metropolis for 17 years.
After this time it was found that the coated plate is not changed its appearance and were not destroyed, while the surface of the control samples were completely covered with corrosion products.
