In the construction and manufacturing sectors, high-strength plastics are increasingly being used. They are superior to traditional hard materials due to their low weight, flexibility in processing and practicality. Nevertheless, metal is preserved in many industries as the most profitable material in terms of combining strength, stiffness and durability. Moreover, the use of an integral structure does not always justify itself. Increasingly, technologists are using metal spraying, which allows to endow the workpiece with a part of the properties of the most suitable alloy in terms of operation.
General information about metallization technologies
Among modern methods of surface metallization, galvanic deposition, as well as immersion in melts, is more often used. Conventional technology also provides vacuum spraying, which has its own classification according to the active media used. One way or another, any metal spraying involves the processing of the base material in order to obtain certain protective qualities. This may be the formation of an anti-corrosion layer, restoration of the lost structure or repair of operational wear.
Moreover, the working surface itself is in most cases subjected to heat treatment. Before applying metal particles, it is melted by burners, inductors or by exposure to low-temperature plasma. In this way, a base is prepared with optimal physicochemical qualities, on which metal is then sprayed in the form of a powder. It is important to note that the same metal, glass, plastics or some types of wood and stones can act as the main material.
Chemical chromium plating method
As an active component for the implementation of such deposition using chemical reagents. The classic composition includes chromium chloride, sodium, acetic acid, as well as water with a solution of caustic soda. The spraying process is carried out at a temperature of about 80 ° C. Work begins with the preparation of material. Usually, chromium plating is used to treat metal surfaces, in particular steel. Before the operation itself, the material is subjected to the primary coating with a copper layer. Next, chemical chromium plating is carried out by means of a sandblasting apparatus connected to a compressor unit. After the procedure is completed, the product is washed in clean water and dried.
Flame treatment method
If the previous technology provides for thorough preparation of the base, which should be coated, then in this case special attention is paid to metallization particles. Modern flame spraying can be performed using polymer powder, wire or cord material. This mass is directed into the flame of an oxygen-propane or acetylene-oxygen burner, in which the air is melted and transferred to the sprayed base. Further, the composition cools, forming a coating ready for use.
Using this technique, materials can be endowed with corrosion resistance and mechanical strength. The active material can be used to process aluminum, nickel, zinc, iron and copper alloys. In particular, flame spraying is used to improve the performance of sliding bearings, insulation coatings, electrical components, etc. In addition, the technology is used in interior and architectural design to provide structures with decorative properties.
Vacuum spraying method
In this case, we are talking about a group of methods that involve the formation of thin films in vacuum when exposed to direct vapor condensation. The technology is implemented in various ways, including through thermal exposure, evaporation by electron and laser beams. Vacuum spraying is used to improve the technical qualities of parts, equipment and tools. For example, this treatment allows the formation of special “working” coatings that can increase electrical conductivity, insulating properties, wear resistance and corrosion protection.
The technology is also used to create decorative coatings. In this case, the technique can be involved in operations requiring high accuracy. For example, vacuum spraying is used in the manufacture of watches with a gold-plated coating, to give frames for spectacles an aesthetic appearance, etc.
Applied Equipment
Most often, devices equipped with a supersonic nozzle are used for spraying. A small-sized electric heater that uses compressed air is also used. A feature of the latter model is the ability to bring the temperature to 600 ° C. Until recently, the use of standard devices, reminiscent of the principle of action of pneumatic guns, was complicated by the fact that the particles wore tool tips. Modern equipment, due to which metal is sprayed, uses the principle of a spray gun. This means that at the time of the passage of the working gas medium through the feed channel, the flow velocity increases as the pipe narrows. At the same time, static pressure also drops. This principle of operation reduces wear and tear and increases the working life of the apparatus.
Conclusion
In order to reduce the cost of technological operations to protect the metal from external influences, highly specialized, but less effective means are often used. At the same time, metal spraying also helps to save money, the price of which is on average 8-10 thousand rubles. for the item. Financial feasibility is due to the fact that such coatings can provide several functional qualities at once. For example, having processed the metal component of the roof structure, you can get such properties as anti-corrosion, resistance to precipitation, and mechanical protection. There are special metallized coatings that can protect the part from aggressive chemical and thermal influences.