Scope of steel products and structures in the modern world is incredibly diverse. Protection of steel from corrosion, and hence increase the life of the products and designs a vital issue for manufacturers and builders. Requirements for galvanizing products dictated by the market, in an environment of strong competition protective coating together with a decorative effect gives a competitive advantage. In construction, the use of galvanized structures are also inevitable, given the climatic conditions of our country. The number of construction projects, with the requirements of the supply of galvanized metal increases annually. If you face the challenge of manufacture any steel products, it is time to think about the protective coating of zinc and choosing a partner.
The two most common methods of galvanizing steel products, zinc galvanic deposition method under the influence of an electric current and hot-dip galvanized in molten zinc.
Electroplating of zinc by two technological ways. The first method is galvanizing a special rotating unit (drum). It is used for galvanizing small loose metal thread and without.
The second method of hanging, hang items on a copper wire and are galvanized in a solution with the electrolyte. It is used for galvanizing various dimensional products.
Hot-dip galvanizing is performed outboard principle applies to large metal.
To select the method of galvanizing, it is necessary to consider the following questions:
The degree of aggressiveness of the environment where the product will be applied.
Aesthetic coverage requirements.
Design features of the product, according to the technological requirements of the galvanizing process.
If the product will be used in an aggressive environment, outdoors, along the roads and in various enterprises, the basic requirement is to cover corrosion resistance. In such cases it is necessary to use a hot-dip galvanizing. The thickness of the zinc coating is 60 micrometers. In the most aggressive environment with high humidity, the year is not degraded more than 10 micrometers zinc coating. It should be noted that the rise of molten zinc products are drops, smudges and various nodules that may interfere with the assembly and installation designs. In developing the drawings necessary to increase the mounting holes and for the assembly to use protective gloves. Since the main objective of hot-dip galvanizing is a corrosion protection, decorative features fade into the background. The thickness of the zinc technology is not standardized, in different places different metal. Technologically, the thickness of zinc is applied at least a certain value, for example, in the construction industry is not widespread requirement of less than 120 micrometers. Hot-dip galvanized steel structures requires special training. This is a topic for another article, a lot of technical difficulties. Required coordination drawings galvanizing plant.
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Electroplating of zinc in addition to protection against corrosion, also performs a decorative function. The coating thickness is several times less than in hot, just 6-9 micrometers. Coverage falls evenly, completely repeating the surface. After galvanizing products undergo compulsory passivation in chromate solution. Since he zinc gray, passivation gives great decorative effect. There are two most common types of passivation, blue (usually white with a blue tint zinc) and rainbow (playing golden color). Galvanic galvanizing method involves only the outer coating products, both inside and in other remote places zinc metal stays, as there is no electrical conductivity. Hot-dip galvanizing provides the inner coating, but also necessarily require technological holes for the flow of zinc, the gas outlet. Consequently, steel products, galvanized by electroplating, find their application is not in a hostile environment, and more moderate. For example, have a rare contact with water, or not long, are periodically outside.
Design features when choosing a method of galvanizing also play a key role. Hot-dip galvanizing is held in the melt at a temperature of 450 degrees Celsius, the thin metal is subjected to deformation. The process of electroplating of zinc takes place at normal room temperature and is often referred to as “cold galvanizing” does not cause deformation of the product. If the product has a threaded connection, the choice is obvious in favor of electroplating of zinc, as the thread coated with a thin layer of zinc.
All plating technologies require high-quality surface preparation of workpieces. Before the galvanizing process must be cleaned from the surface of the scale, technological lubricant residues, corrosion products (rust).
Just consider all the pros and cons of methods of galvanizing, comparing with the operational and technological requirements, it is possible to make the right, the best choice.