To protect the metal from corrosion created many methods and methods. Their essence lies in the fact that a special substance is applied to the surface of the metal. At the final stage, a thin film is formed. It prevents moisture, oxygen, and aggressive substances from entering the surface. Among these methods, galvanizing of metal is distinguished . It is the most effective.
General information
As mentioned earlier, metal galvanizing is the process of applying a special substance to the surface of a product.
Such solutions are based on zinc, which is the most suitable starting material. It prevents corrosion and also protects the surface from aggressive substances. The processed sheet has several advantages:
- product strength increases;
- resistance to various temperatures;
- not exposed to aggressive substances;
- product service life increases;
- the product is not oxidized.
Technological basis
Galvanizing metal is a popular procedure throughout the world. This process consists in applying a special zinc solution to the steel surface. After that, a thin film forms, which performs protective functions, that is, prevents corrosion. Corrosion changes the structure of the metal and renders the product unusable.
How does it rust?
As mentioned earlier, moisture affects products, as well as oxygen and aggressive substances.
Their molecules fall into the deep structure of the metal, which leads to the appearance of rust. As a result, holes appear on the surface. Such a process can take a long time. To slow down the oxidation process, a zinc solution is used.
Stages
Galvanizing of metal consists in coating various types of products with a protective zinc film. To perform this procedure, you must have special equipment. Each element of the device must not be exposed to moisture and aggressive substances. The galvanizing process is divided into the following stages:
- Preparatory. First of all, it is necessary to tidy up the product. Its surface must be cleaned of various substances, and then degrease it. Next is the etching process. The metal product is lowered into a container with an acidic medium. As a rule, a solution of sulfuric acid is used. Due to the etching of the metal, an oxide film appears on the surface. So, the zinc solution will last longer. In the final stage, the remaining acid is removed from the product and dried.
- The process of galvanizing. This stage consists in the fact that a solution is applied to the prepared surface. To make it, it is necessary to melt the zinc in a special bath under the influence of high temperature. When the solution is ready, a metal product is immersed in the bathroom and incubated for several minutes.
- Drying the product. The galvanized product is dried at room temperature.
The process of galvanizing metal products takes place in special bathtubs.
If necessary, they are equipped with sockets. Despite their significant volumes, they also process a large number of small items. Thus, equipment for galvanizing metal and metalware can have not only small, but also large sizes.
Basic processing methods
The most popular way to protect metal products from corrosion is galvanizing. There are various methods for this process. Each of them is applied to a certain type of metal. Some species may react with zinc. There are four types of processing: hot, cold, thermal diffusion, galvanic. Consider each view in more detail.
Hot
Coating products in this way is popular in many countries. Its main positive properties are high quality, as well as a long service life. Therefore, this method has become one of the best. There are also a number of negative properties. First of all, the method is not environmentally friendly, since many chemicals are used at the stage of preparation and galvanizing. In addition, during hot processing there is a significant difficulty. It is necessary to maintain the temperature of zinc in the range from 500 to 5000ΒΊ. To maintain this level of heating consumes a lot of electricity. Hot galvanizing metal at home is a rather complicated process.
Technologically, the process is divided into two stages. This is the preparation and galvanizing of metal. At the first stage, they are engaged in the preparation of a metal product. Its surface must be degreased and cleaned of debris. After this, etching, washing and drying takes place.
These operations are prescribed in the regulatory documentation.
To cover the part with zinc, it is necessary to immerse it in a special bath. It contains a special solution that prevents corrosion. Methods for fixing metal during hot dip galvanizing can be different. They depend on the type and shape of the product. This technology is used in many industries. For example, for the manufacture of galvanized wire, pipes, etc.
After applying the hot method to them, the products have a long service life, that is, they are reliably protected from corrosion. The only difficulty is baths. To process large parts, it is necessary to find a bath of appropriate volumes, which is rather difficult. This feature affects the cost. Where is hot-dip galvanized metal produced? Kursk, Moscow, Chelyabinsk, Yaroslavl - this is just a small list of cities where various companies offer this service. Often they work with large volumes.
Galvanizing of metal - technology
This method is used when smooth surface treatment is required. The galvanizing technology of the metal in a galvanic manner is based on fixing the substance on the surface of the product due to electrochemical effects. This method is suitable for absolutely all types of metal. The product receives a uniform shiny coating. This is due to the merger of the metal and zinc coatings .
This interaction is affected by the presence of various debris or other films on the surface. Therefore, before starting the procedure, you should do the cleaning. In mass production, this is difficult to follow, so galvanizing can be of poor quality.
The galvanic method is based on immersing a metal product in a bath, where there is an electrolyte solution. A current source is connected to the part. In this case, an electrolysis process occurs. Zinc is exposed to it, which covers the metal part.
pros
The main positive quality is the appearance of the product - the surface is smooth and shiny. However, there is a significant drawback. Before draining the solution that was in the bathroom, it is necessary to clean it of zinc. This method produces a large amount of waste that is harmful to the environment. Therefore, it is necessary to purchase special expensive equipment. It will release zinc from the solution. Therefore, this method is one of the most expensive.
How to make metal galvanizing at home?
This procedure is used by many masters when it is necessary to process small parts. First you need to find a suitable container and make an electrolyte. The procedure is carried out in a well-ventilated area and in protective clothing, as electrolyte particles can harm a person. if they get on the skin, a chemical burn is possible. For cooking, take water, zinc sulfide, magnesium and vinegar. Ready concentrate must be filtered. Next, the metal part is lowered into the container and the anode product is prepared. A copper wire is attached to a small piece of zinc, which is connected to the mains. The product is lowered into the electrolyte and the processing process begins. After that, the metal part is dried. Galvanizing of metal at home is quite easy to perform.
Features of the cold method
Over the past years, this method has become widespread. Its essence lies in the fact that a metal product is painted with special substances that contain zinc. This method does not require special skills. However, there are drawbacks: finished galvanized products are subjected to mechanical stress. In addition, it is necessary to constantly monitor the technical personnel who prepare the solution and do the work. As mentioned earlier, this method is quite simple. Therefore, equipment for cold galvanizing of metal is not required. Work must be carried out in accordance with sanitary rules. Using this method, pipes are processed, as well as products that are in a fixed version. To do this, prepare the solution and apply it to the product using a brush or roller. The only equipment for cold galvanizing metal that is used is a spray gun. It helps to reach inaccessible places and perform painting evenly and efficiently. Among the shortcomings, many users note low reliability.
Thermal Diffusion Galvanizing Technology
This method has been used for a long time, but it is popular in our days.
It was first used in England at the end of the 19th century. The invention became famous thanks to the famous scientist Sherard. However, this method was quickly forgotten, replacing it with another. Its revival occurs at the end of the twentieth century. The technology of the thermal diffusion method consists in the fact that the surface of a metal product is treated with zinc in a vapor state. To do this, it must be heated to 2500ΒΊ. The process is carried out in a closed container in the presence of a zinc-containing mixture and metal elements. The technology of this procedure is determined not only by domestic, but also by import regulatory documents.
Thermal diffusion galvanizing is performed when it is necessary to achieve a thickness of 20 ΞΌm. The process is similar to the hot galvanizing method. However, there are differences too. The prepared product is lowered into a drum furnace, where processing occurs due to rotating forces. This process is carried out in 3 hours of operation of this equipment. Using it, various small parts are painted, such as washers and screws.
Unlike the hot method, zinc pollination is applied evenly over the entire surface.
Conclusion
This process helps protect various metal parts from corrosion, moisture, and aggressive substances. There are 4 technological types of galvanizing. Each of them has its own characteristics and is suitable for a certain type of metal. Incompatibility of such components will lead to poor-quality staining and, as a consequence, to a decrease in the strength of the finished product. Galvanizing takes place in special bathtubs or drum furnaces. However, the process can be done at home. For this you need to purchase supplies. Work is carried out in a ventilated room in special protective clothing, as some components cause harm to the human body.