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Gas-dynamic spraying of metal on glass. Gas-dynamic metal spraying

Gas-dynamic metal spraying: purpose, purpose, types of technology. Advantages and disadvantages of the method. Scope of application. Equipment and features of cold spraying.

Gas-dynamic metal spraying is performed with the aim of imparting the necessary properties to the surfaces of metal and non-metal products. This may be an increase in electrical and thermal conductivity, strength, protection from the effects of corrosion processes, restoration of geometric dimensions, etc. However, depending on specific task, depending on the metal of the product, is selected necessary equipment, consumables and spraying technology. Most often, surfaces are subject to metallization, while the applied coating has high adhesion to the material on which it is applied, and the product is mechanically strong. Pure metal powders or mixtures can be sprayed, into which, in addition to the metal component, ceramic powder is introduced in certain quantities. This significantly reduces the cost of powder coating production technology and does not affect its properties.

The essence of the cold gas-dynamic spraying method is to apply and fix on the surface of a product or part solid particles of metal or a mixture of materials ranging in size from 0.01 to 50 microns, accelerated to the required speed in air, nitrogen or helium. This material is called powder. These are particles of aluminum, tin, nickel, babbitts of various brands, a mixture of aluminum powder and zinc. The medium used to move the material can be cold or heated to a temperature not exceeding 700 °C.

Upon contact with the surface of the product, a transformation of the plastic type occurs, and the energy of the kinematic type transforms into adhesive and thermal energy, which contributes to the production of a durable surface layer of the metal. The powder can be applied not only to metal surfaces, but also to those made of concrete, glass, ceramics, and stone, which significantly expands the scope of application of the method of creating surfaces with special properties.

Depending on the pressure, the following types of cold gas-dynamic spraying are distinguished:

high;
low.

In the first case, helium and nitrogen are used as a working medium that moves powder material ranging in size from 5 to 50 microns. Metal particles, if they move, have a pressure of more than 15 atm. In the second case, compressed air is used, which is supplied under a pressure not exceeding 10 atm. These types also differ in such indicators as heating power and working fluid consumption.

The spraying stages are as follows:

preparing the surface of a product for spraying using a mechanical or abrasive method;
heating the working medium (air, nitrogen, helium) to the set temperature technological process temperature;
supplying heated gas to the equipment nozzle along with powder under the required pressure.

As a result, the powder is accelerated in the flow to supersonic speeds and collides with the surface of the part or product. A layer of metal is sprayed with a thickness, the thickness of which depends on the heating temperature of the supplied gas and pressure.

The surface of the product is prepared using an abrasive method using the equipment itself for applying gas-dynamic spraying by simply changing the mode parameters.

The scope of application of this type of spraying is quite extensive. Using the method, they seal leaks in containers and pipelines, repair parts and castings made of light alloys, apply electrically conductive, anti-corrosion and anti-friction coatings, eliminate mechanical damage, and restore seats in bearings.

The main advantages of the method

The advantages of the technology include:

performing work under any climatic conditions (pressure, temperature, humidity);
the possibility of using stationary and portable equipment, which in the latter case allows for work to be carried out at the location;
possibility of applying coating to local areas (defective areas);
the ability to create layers with different properties;
the ability to create a layer of the required thickness or different thicknesses in multilayer coatings;
the process does not affect the structure of the product being sprayed, which is an important advantage;
safety;
environmental friendliness.

The disadvantage of this type of spraying is only one fact. The layers can be applied to ductile metals such as copper, zinc, aluminum, nickel and alloys based on them.

Manufacturers different countries produce stationary and portable equipment for manual and automated coating application different performance for different metals.

Equipment used

The apparatus for gas-dynamic metal spraying consists of the following main parts:

powder containers;
working fluid supply systems, including a compressed gas cylinder and all the necessary components for it;
nozzles (as a rule, there are several of them, they are of different configurations and are used for different spraying modes);
control panel.

In the Russian Federation, high-quality equipment for spraying using the gas-dynamic method is produced by the powder spraying center in Obninsk under the trademark “DIMET”. It meets the requirements of domestic GOSTs, is certified and protected by patents in many countries, including Russia.

The process of repairing a part using gas dynamic spraying is shown in the video:

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By the way, Obninsk engineers have already developed several modifications of DIMET installations. Considering the wide demand for this equipment, both manual and automated cold gas-dynamic spraying devices are now being mass-produced, which allows them to be used in industry, oil and gas industry, as well as in small businesses for processing small parts. Moreover, there is nothing particularly complicated in the technology itself. To operate the complex (in addition to the material for spraying), only compressed air is required (supplied at a pressure of 0.6-1.0 MPa and a flow rate of 0.3-0.4 m3/min.) and a 220 V power supply.

Now let's talk about the advantages and disadvantages of the method. Metal spraying equipment from China? Firstly, unlike the gas-thermal method, CGN can be effectively used at normal pressure, in any temperature range and humidity level.

Secondly, it is absolutely environmentally safe. Thirdly, due to its high speed, it can also be used for abrasive cleaning of surfaces. Well, the only drawback of the technology is the possibility of applying coatings only from relatively ductile metals, such as copper, aluminum, zinc, nickel, etc.

Scope of application of CGN

I would like to dwell in more detail on the areas of use of cold gas dynamic spraying technology with powder materials in order to clearly show how in demand it is today.

Elimination of defects, restoration of surfaces and sealing

All of this is work that even small businesses can do. For example, in small workshops you can repair parts made of light alloys (parts of an automobile structure, for example), primarily aluminum and aluminum-magnesium. Moreover, defects that arise both during the production process and during operation are easily eliminated.

And the absence of strong heating and low energy of the method make it possible to repair even thin-walled products.

CGN is also excellent for restoring worn surfaces. For example, such a labor-intensive process as “building up” metal in bearing seats can now be carried out even by small enterprises, not to mention restoring sealing (when the use of liquid sealants is impossible) in pipelines, heat exchangers or vessels for working gases and liquids.

High-precision restoration of parts of various mechanisms, current conduction

CGN very effective in repairing complex products that require precise restoration of geometric parameters, elimination of hidden defects, but at the same time maintaining all operational characteristics, as well as presentation. That is why this method is actively used in the military-industrial complex, railway and aviation industries, agriculture, gas pumping, etc.

You cannot do without this technology in creating contact pads. Prices for metal spraying equipment? Due to the possibility of easy coating on any metal, ceramic and glass surfaces, CGN is also used in the production of electrical products. For example, in copper plating processes, creating power current-carrying networks, applying current leads, making sublayers for soldering, etc.

Anti-corrosion treatment and elimination of deep defects

Spraying a so-called anti-friction coating is a highly effective way to get rid of local damage (deep chips, burrs, scratches). This allows you to avoid the procedure of complete refilling or even replacing the product, which, of course, is not economically profitable.

And in anti-corrosion treatment and protection against high-temperature corrosion of various communications this method there are no equals at all. By the way, various equipment modifications DYMET ® provide high-quality processing of the inner surface of pipes with a diameter of 100 mm and a length of up to 12 m.

Additional information:

Heat-resistant coatings are applied using the gas-dynamic method, which provide protection up to 1000-1100 degrees Celsius. Electrical conductivity is on average 80-90% of the electrical conductivity of the bulk material. Corrosion resistance depends on the characteristics of the aggressive environment.

The operation of DYMET equipment, developed and mass-produced by the Obninsk Powder Spraying Center (OTsPN LLC), is based on the effect of fixing metal particles, if they move at supersonic speed, on the surface upon impact with it, gas-dynamic spraying of metals DYMET. The technology makes it possible to apply metal coatings not only to metals, but also to glass, ceramics, stone, and concrete. To date, DYMET technology makes it possible to apply coatings of aluminum, zinc, copper, tin, lead, Babbitt, nickel and apply them not only to metals, but also to glass, ceramics, stone, and concrete.

Plakart specialists produce coatings using the gas-dynamic method for industrial equipment (for example, in the photo - anti-corrosion coating of a heat exchanger without dismantling). In addition, we supply turnkey cold gas dynamic spraying plants (setup, service, training).

Depending on the composition of the consumable material (powder) and changes in its application modes, you can obtain a homogeneous or composite coating with a solid or porous structure and its own functional purpose. This can be: restoration of the geometry of the product, strengthening and protecting the metal from corrosion, increasing the thermal and electrical conductivity of the material, as well as the formation of a wear-resistant coating that can withstand exposure to chemically active environments, high thermal loads, etc.

In the description of Browning's invention, these problems are discussed, but not resolved. Exit from this provision discovers a spraying method in which the powder is not heated to a molten state. The idea of the possibility of “cold welding” of small metal particles during high-speed collision with a hard surface was expressed in Shestakov’s invention back in 1967. The proposal for cold welding of particles in a dynamic mode was not developed at that time.

Equipment for cold gas-dynamic spraying of metals? Because To implement the cold spraying mode, new proposals for the design of the nozzle assembly were needed.

Cold gas dynamic spraying is the latest method in the field of thermal spraying. Compared to conventional thermal spray processes, cold gas dynamic spray has particular advantages because the sprayed material does not melt or melt during the process. Thus, the thermal impact on the coating and the substrate material remains low.

The high kinetic energy of the particles and the high degree of deformation when exposed to the substrate that is connected to it makes it possible to produce homogeneous and very dense coatings. The coating thickness ranges from a few hundredths of a millimeter to several centimeters.

In the resulting metal coatings, physical and chemical properties practically do not differ from the properties of the base material.

According to the latest system technology from Impact Innovations GmbH, an inert gas - preferably nitrogen or helium - is supplied to the spray gun at a pressure of up to 50 bar (725 psi) and heated to a maximum temperature of 1100 °C (2012 °F) at pistol body.

Subsequent expansion of heated and high-pressure gas in a converging-diverging nozzle to pressure environment leads to acceleration of the process inert gas to supersonic speed and at the same time cooling the gas to a temperature below 100 °C (373 °F).

The atomized powders are injected into the converging part of the nozzle using a powder and carrier gas feeder and accelerated to a particle speed of 1200 m/s in the main gas flow.

In the highly constricted spray nozzle, particles strike the mostly untreated component surfaces, are deformed, and are converted into a highly adhesive/cohesive, low-oxide coating.

Impact of Particle Velocity on Coating Quality and Efficiency

The coating particle has reached the minimum impact speed, which is necessary to initiate the mechanism of interaction with the surface of the substrate (processed sample). This so-called “critical speed” affects the properties of the coating material.
Since the impact speed is higher than the critical speed, the deformation and quality of adhesion of the particles increase.
If the impact velocity is too high (the "erosion rate"), more material is destroyed than added. No coating is formed.
To form a dense and well-formed coating, the particle impact velocity must be between the critical velocity and the erosion rate.

What can be coated using cold gas dynamic spraying?

Coating materials

Metals: for example, magnesium, aluminum, titanium, nickel, copper, tantalum, niobium, silver, gold, etc.

Alloys: for example, nickel-chrome, bronze, aluminum alloys, brass, titanium alloys, MCrAlY powders (alloys based on a base metal (Co, Ni, Cr, Fe) with the addition of chromium, aluminum and yttrium), etc.

Mixed materials(metal matrix combined with solid phases): e.g. metal and ceramics, composites.

Base materials

Metal products and samples, plastics, as well as glass and ceramics.

Individual processing

Each individual material is processed individually.

Material processing requires individual adjustment of gas temperature and pressure. The combination of these two physical parameters determines the particle speed and the quality of the coating. The range of optimal spray velocity, limited by the critical velocity and the erosion rate, is called the deposition range. Within this range, the quality of coating application is influenced by parameters.

Gas-dynamic spraying is a technology for applying a metal coating to various materials and products for protective or decorative purposes, in which the formation of a surface layer occurs due to the impact of particles of the applied substance on the surface of the coated workpieces. Gas-dynamic spraying can be cold (CGN) and pulsed (IGN). In the first case, the particles are not heated, and their acceleration is ensured using a supersonic gas flow. In the second, average heating and acceleration of particles occurs by a series of shock waves of a fixed frequency.

Enterprises in the Moscow region

Moscow region, Sergiev Posad, Red Army Ave., 212B, bldg. 8

Experience (years): 11 Employees: 20 Area (m²): 1400 Stankov: 30

Slotting Tool sharpening Countersinking holes Gear shaping Gear hobbing Gear grinding work Jig boring work Thread rolling Threading Surface grinding work Reaming holes Locksmith work Automatic turning works Electrical discharge machining HDTV hardening Bulk hardening Aluminizing Anodizing Gas dynamic spraying Oxidation Cementation Laser cutting Plasma cutting Gas welding Gas press welding Diffusion welding Arc press welding Resistance welding Forge welding Robotic welding Manual arc welding Submerged arc welding Thermite welding Powder painting Working with stainless steel Ultrasonic testing

Moscow region, Istra, st. Panfilova, 11

Experience (years): 61 Employees: 500 Area (m²): 10000 Stankov: 86

Horizontal boring work Countersinking holes Jig boring work Cylindrical grinding work Machining at the machining center Thread rolling Threading Surface grinding work Reaching out Reaming holes Thread grinding work Drilling holes on CNC machines Drilling holes on universal machines Locksmith work Turning on CNC machines Turning on universal machines Automatic turning works CNC milling Milling on universal machines Honing Spline milling processing Electrical discharge machining Dispersed hardening Hardening HDTV Normalization Bulk hardening Annealing of metal Tempering of metal Surface hardening Sorbitization Metal enhancement Boroalitizing Gas dynamic spraying Thermal spraying Electroplating with copper (copper plating, copper plating) Nickel electroplating (nickel plating) Electroplating with chrome (chrome plating) Electroplating with zinc (zinc plating, galvanizing) Carbonitration Nitrocarburization Thermal diffusion galvanizing Metal etching Chemical phosphating Chromoalitation Chromosiliconation Laser cutting Shaped pipe cutting Sheet metal rolling Profile rolling Rolling of bar metal Profile bending Bending of bar metal Pipe bending Argon (argon arc) welding Gas welding Gas press welding Resistance welding Metal cutting Sheet stamping Metal perforation Metal punching Rolling out Manufacturing of parts according to customer drawings Manufacturing of non-standard metal structures Laser engraving Aluminum processing Titanium processing Painting with a brush Painting with a spray gun Powder painting Working with stainless steel Working with galvanized steel

Moscow region, Mytishchi district, Krasnaya Gorka village, st. Shkolnaya, 38

Experience (years): 6 Employees: ? Area (m²): ? Stankov: ?

Turning on CNC machines Dispersed hardening HDTV hardening Cryogenic treatment Normalization Bulk hardening Annealing of metal Tempering of metal Surface hardening Sorbitization Metal enhancement Nitriding Aluminizing Anodizing Boriding Boroalitizing Gas dynamic spraying Thermal spraying Electroplating with copper (copper plating, copper plating) Nickel electroplating (nickel plating) Electroplating with chrome (chrome plating) Electroplating with zinc (zinc plating, galvanizing) Carbonitration Multi-layer copper and nickel plating Multi-layer copper, nickel and chrome plating Nitrocarburization Oxidation Cladding Siliconization Thermal diffusion galvanizing Metal etching Chemical phosphating Chromoalitation Chromosiliconation Cementation Cyanidation Electrochemical metal polishing Gas/flame/oxygen cutting Waterjet cutting Laser cutting Plasma cutting Cross cutting of steel coils Slitting of coiled steel Longitudinal and transverse cutting of coiled steel Rebar cutting Cutting on a band saw Cutting with press shears Guillotine cutting Shaped pipe cutting Sheet metal rolling Profile rolling Rolling of bar metal Pipe rolling 3D wire bending Sheet metal bending Press bending Profile bending Bending of bar metal Pipe bending Argon (argon arc) welding Gas welding Gas press welding Diffusion welding Arc press welding Resistance welding Forge welding Laser welding Surfacing Soldering Semi-automatic arc welding Robotic welding Manual arc welding Welding reinforcement Explosion welding Submerged arc welding Friction welding Pipe welding Thermite welding Ultrasonic welding Chemical welding Cold welding Electron beam welding Drawing Metal cutting Forging Sheet stamping Volume stamping Metal perforation Straightening of flat rolled metal Metal pressing Metal punching Metal rolling Rolling-drawing Rolling-pressing Farting Rolling out Cutting metal on a jig press Artistic forging Visual and measuring control Manufacturing of parts according to customer samples Manufacturing of parts according to customer drawings Manufacturing of non-standard metal structures Manufacturing of standard metal structures Penetrant control Laser engraving Magnetic particle testing Plasma marking Aluminum processing Processing in a tumbling drum Shot blasting Titanium processing Rewinding of metal rolls Sandblasting Painting with a brush Painting with a spray gun Powder painting Working with reinforcement Working with stainless steel Working with galvanized steel Development of 3D models from drawings Ultrasonic thickness gauging Ultrasonic testing Chemical analysis

Gas dynamic spraying

The main goal of gas-dynamic metal spraying is to impart certain properties to the surfaces of workpieces. This procedure is performed not only for metal workpieces, but also for other materials. It is aimed at increasing strength characteristics, electrical and thermal conductivity. This technology provides protection against corrosion and restores geometric dimensions. Enterprises providing gas dynamic metal spraying services in Moscow, cope with this task perfectly, because they have high-tech equipment at their disposal.

In most cases, surfaces are metallized, and the applied coatings have excellent adhesive properties. The adhesion to the base is as reliable as possible, and the products gain additional strength. Only metal powders or substances containing, in addition to metal, also a ceramic component in certain dosages can be sprayed. This significantly reduces the cost of the powder coating formation method and does not affect its characteristics. The essence of the cold gas-dynamic spraying technique is to apply and fix solid metal particles or mixtures of materials on the surface of elements. Their size is 0.01-50 microns. They accelerate to the required speed in air, ozone or helium. Such material is called powder.

These are aluminum particles, nickel particles, combinations of aluminum with zinc. The medium used to mix the material can be hot or cold. In the first case, the maximum heating is 700 degrees. When interacting with the surface of the product, a lamellar transformation takes place, the kinematic energy is transformed into adhesive and thermal energy. Due to this, a durable surface layer is formed. The powder is applied not only to metal surfaces, but also to concrete, glass, ceramic, and stone. This significantly expands the scope of use of the technique for forming surfaces with specific properties.

Gas dynamic spraying can be high or low - this depends on the pressure level. In the first case, the working medium that moves the powder is nitrogen and helium. Moving metal particles have a pressure of over 15 atm. In the second case, compressed air is used, supplied at a pressure of no more than 10 atm. The differences between these types also lie in the heating power and the consumption of the working medium. Spraying is performed in several stages, including:

Preparing the surface for applying powder (using a mechanical or abrasive method).
Heating the working environment to the required temperature.
Supply of heated gas into a special nozzle under the required pressure (gas is supplied along with the powder).
The powder acquires enormous speed and comes into contact with the surface of the product.

The cost of gas-dynamic metal spraying services in the Moscow region is quite affordable.

In fact, it is a more advanced version of the long-proven gas-thermal method for restoring various metal parts and surfaces. Cold Spray or simply CGN significantly expands the capabilities of the “hot” method of processing products.

Currently, it is undoubtedly the most advanced technology for the recovery and protection of materials, which has become widespread in both the industrial and civil sectors.

Principle of action, pros and cons of CGN

It has two main differences from the gas-thermal restoration method. Firstly, spraying of a protective or restorative coating occurs at a low temperature not exceeding 150 °C, which in turn does not cause stress in the parts being processed and their deformation. Secondly, “cold” technology allows you to create a layer of adjustable thickness and within precisely specified boundaries. We’ll talk about other pros and cons a little later, but for now about the authors of the method and how it works.

Its developer is "Obninsk Powder Coating Center"(Russia). The equipment they produce is called DYMET ®. It is certified according to the GOST R system and is protected by patents from Russia, the USA, Canada and other countries. The technology is based on the principle of supersonic impact of tiny particles of fusible and other materials on the surface being treated. These are mainly polymers or alloys of carbides with metals with a particle size of 0.01-0.5 microns. Mixing with gas, they are supplied to the product at a speed of 500-1000 m/s.

By the way, Obninsk engineers have already developed several modifications of DIMET ® installations. Considering the wide demand for this equipment, both manual and automated cold gas dynamic spraying devices are now being mass-produced, which allows them to be used in industry, the oil and gas industry, as well as in small businesses for processing small parts. Moreover, there is nothing particularly complicated in the technology itself. To operate the complex (in addition to the material for spraying), only compressed air is required (supplied at a pressure of 0.6-1.0 MPa and a flow rate of 0.3-0.4 m3/min.) and a 220 V power supply.

Now about the advantages and disadvantages of the method. Firstly, unlike the gas-thermal method, CGN can be effectively used at normal pressure, in any temperature range and humidity level. Secondly, it is absolutely environmentally safe. Thirdly, due to its high speed, it can also be used for abrasive cleaning of surfaces. Well, the only drawback of the technology is the possibility of applying coatings only from relatively ductile metals, such as copper, aluminum, zinc, nickel, etc.

Scope of application of CGN

I would like to dwell in more detail on the areas of use of cold gas dynamic spraying technology with powder materials in order to clearly show how in demand it is today.

Elimination of defects, restoration of surfaces and sealing

It is very effective in repairing complex products that require precise restoration of geometric parameters, elimination of hidden defects, but at the same time maintaining all operational characteristics, as well as presentation. That is why this method is actively used in the military-industrial complex, the railway and aviation industries, agriculture, gas pumping, etc.

You cannot do without this technology in creating contact pads. Due to the possibility of easy coating on any metal, ceramic and glass surfaces, CGN is also used in the production of electrical products. For example, in copper plating processes, creating power current-carrying networks, applying current leads, making sublayers for soldering, etc.

Anti-corrosion treatment and elimination of deep defects

Spraying a so-called anti-friction coating is a highly effective way to get rid of local damage (deep chips, scuffs, scratches). This allows you to avoid the procedure of complete refilling or even replacing the product, which, of course, is not economically profitable.

And in anti-corrosion treatment and protection against high-temperature corrosion of various communications, this method has no equal at all. By the way, various equipment modifications DYMET ® provide high-quality processing of the inner surface of pipes with a diameter of 100 mm and a length of up to 12 m.