Zinc plating: technology and methods

Many methods and methods have been developed to protect the metal from corrosion. Their essence lies in the fact that a special substance is applied to the metal surface. At the final stage, a thin film forms. It prevents the ingress of moisture, oxygen, and also aggressive substances to the surface. Among these methods, metal zincification is distinguished. It is the most effective.

General information

As mentioned earlier, galvanizing metal is the process of applying a special substance to the surface of the product. Such solutions are based on zinc, which is the most suitable starting material. It prevents corrosion, and also protects the surface from the effects of corrosive substances. The processed sheet has several advantages:

• Increases the strength of the product;
• Resistance to different temperatures;
• Not exposed to corrosive substances;
• Increases the service life of the product;
• The product is not oxidized.

Technological basis

Zinc plating is a popular procedure all over the world. The given process consists that on a steel surface the special zinc solution is put. After this, a thin film forms, which performs protective functions, that is, prevents corrosion. Corrosion changes the structure of the metal and causes the product to become unusable.

How does it rust?

As stated earlier, the products are exposed to moisture, 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. This process can take a long time. To slow the oxidation process, use a zinc solution.

Stages

Zinc coating of metal consists in coating with protective zinc film of various types of products. To perform this procedure, you need to have special equipment. Each element of the device must not be exposed to moisture and aggressive substances. The process of galvanizing is divided into the following stages:

1. Preparatory. First of all, you need to fix the product. Its surface must be cleaned of various substances, and then degrease it. Then the etching process takes place. The metal product is lowered into a container with an acidic medium. As a rule, a solution of sulfuric acid is used. Thanks 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 remains of acid are removed from the product and dried.
2. The process of galvanizing. This stage consists in applying a solution 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, the metal product is immersed in the bath and allowed to stand for several minutes.
3. Drying the product. The galvanized product is dried at room temperature.

The process of galvanizing of metal products takes place in special baths.

If necessary, they are equipped with sockets. Despite their considerable 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 zinc coating. There are various ways of this process. Each of them is used for a certain type of metal. Some species can react with zinc. There are four types of treatment: hot, cold, thermodiffusion, galvanic. Let's consider each species in more detail.

Hot

Covering 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 is also a number of negative properties. First of all, the method is not environmentally safe, since a lot of chemicals are used at the preparation and galvanizing stage. In addition, with hot processing there is a significant difficulty. It is necessary to maintain the temperature of zinc in the range from 500 to 5000ºС. To maintain this level of heating, a lot of electricity is expended. Hot-dip galvanized metal at home is a rather complicated process.

Technologically, the process is divided into two stages. This is the preparation and galvanizing of the metal. At the first stage, they prepare the metal product. Its surface must be degreased and cleaned of debris. After that, there is etching, washing and drying.

These operations are prescribed in the regulatory documentation.

To cover with zinc a detail, it is necessary to immerse it in a special bath. It contains a special solution, which prevents the appearance of corrosion. Methods of fixing the 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 production of galvanized wire, pipes, etc.

After applying hot method to them, the products have a long service life, that is, they are reliably protected from corrosion. The only difficulty is the bath. To handle large parts it is necessary to find a bath of appropriate volumes, which is quite difficult. This feature affects the cost. Where is the hot-dip galvanizing of metal? Kursk, Moscow, Chelyabinsk, Yaroslavl is only a small list of cities where different companies offer this service. Often they work with large volumes.

Galvanic galvanizing of metal - technology

This method is used when a smooth surface treatment is required. Galvanizing technology of metal is based on fixing the substance on the surface of the product due to electrochemical exposure. This method is suitable for all types of metal. The product receives a uniform shiny coating. This is due to the fusion of the metal coating and zinc.

This interaction is influenced by the presence on the surface of various debris or other films. Therefore, before starting the procedure, you should clean up. When mass production is difficult to follow, therefore, the zinc coating may be substandard.

Galvanic method is based on immersing a metal product in a bath, where the electrolyte solution is located . A power source is connected to the part. In this case, an electrolysis process occurs. He is exposed to zinc, 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. With this method, a large amount of waste is generated, which harms 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 galvanizing metal 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 room and in protective clothing, since particles of electrolyte can harm a person. If they get on the skin, a chemical burn is possible. For cooking, take water, zinc sulphide, magnesium and vinegar. Ready concentrate should be filtered. Further, the metal part is lowered into the container and the anode product is prepared. A small piece of zinc is attached to a copper wire, 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. Galvanic galvanizing metal at home is quite easy.

Features of the cold method

Over the past few years, this method has become widespread. Its essence lies in the fact that the metal product is painted with special substances that contain zinc. This method does not require special skills. However, there are also disadvantages: the finished galvanizing products are subjected to mechanical influences. In addition, it is necessary to constantly monitor the technical staff, who prepares the solution and performs the work. As mentioned before, this method is quite simple. Therefore, equipment for cold galvanizing of the metal is not required. The work must be carried out in accordance with the sanitary and hygienic rules. With 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 with a brush or roller. The only equipment for cold galvanizing of the metal that is used is a spray gun. It helps to reach inaccessible places and to perform painting evenly and qualitatively. Among the shortcomings, many users have noted low reliability.

Technology of thermal diffusion galvanizing

This method is used for a long time, but it is popular in our days.

It was first used in England in the late 19th century. The invention became known due to the well-known scientist Sherard. However, this method was quickly forgotten, replacing it with another one. His revival is at the end of the twentieth century. The technology of the thermodiffusion method consists in the fact that the surface of the metal product is treated with zinc, which is in the vapor state. To do this, it must be heated to 2500 ° C. The process is carried out in a sealed container with a zinc-containing mixture and metal elements in it. The technology for carrying out this procedure is determined not only by domestic, but also by import regulatory documents.

Thermodiffusion galvanizing is carried out when it is necessary to achieve a thickness of 20 μm. The technological process is similar to the hot method of galvanizing. However, there are differences too. The prepared product is lowered into a rotary kiln where processing is performed due to the rotating forces. This process is performed in 3 hours of operation of this equipment. With the help of its painted various small details, such as washers and screws.

Unlike the hot method, the application of zinc dusting occurs evenly over the entire surface.

Conclusion

This process helps to 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. The incompatibility of such components will lead to poor coloration and, as a consequence, to a decrease in the strength of the finished product. Zinc coating takes place in special baths or drum furnaces. However, the process can be performed at home. To do this, you need to purchase supplies. Work is carried out in a ventilated area in special protective clothing, as some components are harmful to the human body.