Гальванизация перед порошковым покрытием

Cover the metal with metal so that the metal under the metal does not oxidize. Or metal protection of metal against corrosion. This could be the headline of this article. Sounds strange and attracts a lot of attention at the same time. What is the logic? How it works? Won’t the protective layer be destroyed along with the product?

This is all the magic of galvanization and in this article we tell the details about its types, functions, advantages and application features.

What is galvanization?

Galvanization of metal is one of the possible, or sometimes extremely necessary, metal processing processes. As you know, in addition to giving the required shape to a metal product, it is necessary to take care of its surface and reliably protect it from possible pests. Metal objects, structures or small elements of structures, machinery, equipment and any other tool are threatened by corrosion. This does not depend on the strength of the metal, because the penetration of corrosion into individual layers is a long process, sometimes completely invisible until holes appear. It is inevitable because it is a natural process.

When a metal comes into contact with oxygen and hydrogen, a chemical oxidation reaction occurs. As a result, rust is formed, which only at the beginning gives a slight bloom, and already over time begins to confidently “eat up” the material. Since constant contact with air in the environment cannot be eliminated or even limited in any way, and for one device or metal element, it is also not the best option to create vacuum conditions, one thing remains – to create protection on the surface.

In order to reliably protect metal from corrosion, metal covering technology has been developed over the years. At first, these were liquid paints, which are still in demand due to their ease of application and low cost. But more and more powder paints are replacing them. Such paints are characterized by the fact that they adhere to the surface in a thin layer as reliably as possible thanks to a special baking technology – polymerization. But sometimes this is not enough. You need to clearly know how to prepare the surface for application, clean up any foreign residues that may prevent the paint from adhering tightly, and also neutralize any possibility of oxidation before painting.

And electroplating is one of the stages of surface treatment and preparation for painting. It is especially relevant when it comes to products with many bends, fasteners, and seams.

Electroplating is the application of a thin layer of metal to a product. Before proceeding with the analysis of the types of electroplating and their differences, you need to understand the preliminary preparation processes. Every surface needs cleaning. For this, heat treatment is performed, in the presence of severe contamination, shot blasting or mechanical treatment is used. This will make the surface smooth and facilitate the application of electroplating materials.

So galvanization is designed to:

  • to increase the hardness of the metal, which is painted, and therefore impact resistance;
  • to reduce the risks of metal fatigue and its rapid wear;
  • to increase the anti-corrosion functions of the coating at times;
  • optionally create additional decorative properties.

How is the type of metal processing determined and why is electroplating prevailing over others?

Additional protective properties of metal can be given by the following methods:

  • metallization

It is carried out by spraying hot liquid metal onto the surface using air currents.

  • galvanization

An electric current is used, which is created when the material is passed through the electrolyte for processing. In this case, metals, alloys or even aqueous solutions of their salts can be used.

  • cladding

Under these conditions, a stronger type of metal is chosen and a thin protective layer is cast on the surface of the material, which will react less to aggressive factors.

  • diffuse method

The metal and its metal coating are fused together at high temperatures, allowing them to evenly penetrate each other.

Pros of galvanization

The main advantage of electroplated coatings is that even with deep scratches on the surface, they will not lose their anti-corrosion properties. To figure out how this is possible, you need to trust a little science. The above listed coatings can be divided into anodic and cathodic ones. It depends on the characteristics of the metal from which the coating will be made, whether it is an anode or a cathode. Different types of coating require different types of metals. For example, some will melt and spray better when hot, while others will only need to be cast using casting methods.

Anodes allow for electrochemical protection. Then, in a humid environment, a galvanic cell is formed on the surface. Such a self-feeding system, tuned to combat corrosion. Simply put, the anodes will be destroyed under the influence of the environment, while forming additional protection on the base material. That is, according to the methods of galvanic treatment, a plaque will form, as well as with rust, but it will not destroy the walls of the metal, but on the contrary will not allow atmospheric factors to penetrate deeper.

How is electroplating performed?

The application process is very simple. A metal product is immersed in a special bath, where, under the influence of current, in a fairly short period of time, it is covered with a thin film of the required metal. There are different types of electroplating, which differ in the metals in the composition:

  • Oxidation (performed by aluminum and its alloys);

There is thermal (bluing), chemical and electrochemical oxidation. The main task is to form a protective film as a result of a rapid chemical reaction.

  • Nickel plating (copper and copper alloys);

Its peculiarity lies in giving a beautiful shine on the surface, therefore it is often used for decorative purposes.

  • Chrome plating (copper, carbon alloys and alloys);

The surface is saturated with chromium under the influence of high temperatures, or it is embedded from the electrolyte.

  • Copper plating (carbon alloys);

Has a high degree of adhesion, as well as an attractive appearance

  • Cadmium plating (carbon alloys);
  • Electropolishing with stainless steel;
  • Chemical passivation;

It is especially widely used for creating stainless steel surfaces.

Electroplating is a highly effective way to create corrosion protection. Due to the fact that the metals in the coating are resistant to corrosion, it is possible to easily protect the material of the product. Most of all attention is usually paid to the mountings. These places are vulnerable and most of all subject to exploitation, and therefore the influence of negative factors run faster. Therefore, all modern fasteners must go through the galvanic treatment process.

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