Ionic nitriding.

Sometimes this process is called ionitriding or nitriding in a glow discharge plasma. The essence of this method is that a rarefied nitrogen-containing atmosphere is created in a sealed container. For this purpose, you can use pure nitrogen, ammonia or a mixture of nitrogen and hydrogen. Nitrided parts are placed inside the container and connected to the negative pole of a constant voltage source. They play the role of a cathode. The anode is the container wall. A high voltage (500-1000 V) is switched between the cathode and anode. Under these conditions, gas ionization occurs. The resulting positively charged nitrogen ions rush to the negative pole - the cathode. The electrical resistance of the gaseous medium near the cathode increases sharply, as a result of which almost all the voltage supplied between the anode and cathode falls on the resistance near the cathode, at a distance of several millimeters from it. This creates very high tension. electric field near the cathode.

Nitrogen ions, entering this zone of high tension, are accelerated to high speeds and, colliding with the part (cathode), are introduced into its surface. In this case, the high kinetic energy that the nitrogen ions had turns into thermal energy. As a result, in a short time, approximately 15–30 minutes, the part is heated to a temperature of 470–580°C, at which nitrogen diffusion occurs deep into the metal, i.e., the nitriding process occurs. In addition, when ions collide with the surface of a part, iron ions are knocked out from its surface. Thanks to this, the surface is cleaned of oxide films that prevent nitriding. This is especially important for the nitriding of corrosion-resistant steels, in which such a passivating film is very difficult to remove by conventional methods.

Ion nitriding compared to nitriding in furnaces has the following advantages:

1) reduction of the total duration of the process by 1.5-2 times;

2) the ability to regulate the process in order to obtain a nitrided layer with specified properties;

3) less deformation of parts due to uniform heating; 4) the possibility of nitriding corrosion-resistant steels and alloys without additional depassivating treatment.

Ion plasma nitriding (IPA)- This is a type of chemical-thermal treatment of machine parts, tools, stamping and casting equipment, ensuring diffusion saturation of the surface layer of steel (cast iron) with nitrogen or nitrogen and carbon in a nitrogen-hydrogen plasma at a temperature of 450-600 ° C, as well as titanium or titanium alloys at temperature 800-950 °C in nitrogen plasma.

The essence of ion plasma nitriding is that in a nitrogen-containing gas environment discharged to 200-000 Pa between the cathode on which the workpieces are located and the anode, the role of which is played by the walls of the vacuum chamber, an anomalous glow discharge is excited, forming an active medium (ions, atoms, excited molecules). This ensures the formation of a nitrided layer on the surface of the product, consisting of an outer nitride zone with a diffusion zone located underneath it.

By varying the composition of the saturating gas, pressure, temperature, and holding time, it is possible to obtain layers of a given structure with the required phase composition, ensuring strictly regulated properties of steels, cast irons, titanium or its alloys. Optimization of the properties of the hardened surface is ensured by the necessary combination of nitride and diffusion layers, which grow into the base material. Depending on the chemical composition, the nitride layer is either a y-phase (Fe4N) or an e-phase (Fe2-3N). The e-nitride layer is corrosion-resistant, while the y-nitride layer is wear-resistant but relatively ductile.

At the same time, with the help of ion plasma nitriding it is possible to obtain:

diffusion layer with a developed nitride zone, providing high corrosion resistance and wearability of rubbing surfaces - for parts subject to wear

diffusion layer without nitride zone - for cutting, stamping tools or parts operating at high pressures with alternating loads.

Ion plasma nitriding can improve the following characteristics products:

wear resistance

fatigue endurance

anti-scuff properties

heat resistance

corrosion resistance

The main advantage of the method is stable processing quality with minimal variation in properties from part to part, from charge to charge. In comparison with widely used methods of strengthening chemical-thermal treatment of steel parts, such as carburization, nitrocarburization, cyanidation, gas nitriding, the ion plasma nitriding method has the following main advantages:

higher surface hardness of nitrided parts

no deformation of parts after processing

increasing the endurance limit with increasing wear resistance of processed parts

more low temperature process, due to which there are no structural changes in the processed parts

possibility of processing blind and through holes

maintaining the hardness of the nitrided layer after heating to 600 - 650 °C

possibility of obtaining layers of a given composition

possibility of processing products of unlimited sizes of any shape

no pollution

improving production standards

reduction in processing costs several times

The advantages of ion plasma nitriding are manifested in a significant reduction in basic production costs. For example, compared to gas nitriding, IPA provides:

reduction in processing time from 2 to 5 times, both by reducing the heating and cooling time of the charge, and by reducing the isothermal holding time

reduction in the consumption of working gases (20 - 100 times)

reduction in energy consumption (1.5 - 3 times)

Reduces deformation enough to eliminate finishing sanding

improvement of sanitary and hygienic production conditions

full compliance with technology for all modern requirements on environmental protection

Compared to hardening, treatment by ion plasma nitriding allows:

eliminate deformations

increase the service life of the nitrided surface (2-5 times)

The use of ion plasma nitriding instead of carburization, nitrocarburization, gas or liquid nitriding, volumetric or high-frequency hardening allows:

save capital equipment and production space

reduce machine costs, transport costs

reduce the consumption of electricity and active gas media.

The main consumers of equipment for ion plasma nitriding are automobile, tractor, aviation, shipbuilding, ship repair, machine / machine tool factories, factories for the production of agricultural machinery, pumping and compressor equipment, gears, bearings, aluminum profiles, power plants...

The ion plasma nitriding method is one of the most dynamically developing areas of chemical-thermal treatment in industrialized countries. The IPA method has found wide application in the automotive industry. It is successfully used by the world's leading auto/engine manufacturing companies: Daimler Chrysler (Mercedes), Audi, Volkswagen, Voith, Volvo.
For example, the following products are processed using this method:

injectors for passenger cars, automatic drive support plates, dies, punches, dies, molds (Daimler Chrysler)

springs for injection system (Opel)

crankshafts (Audi)

camshafts (Volkswagen)

crankshafts for compressor (Atlas, USA and Wabco, Germany)

gears for BMW (Handl, Germany)

bus gears (Voith)

hardening of pressing tools in the production of aluminum products (Nughovens, Scandex, John Davis, etc.)

There is positive experience of industrial use this method CIS countries: Belarus - MZKT, MAZ, BelAZ; Russia - AvtoVAZ, KamAZ, MMPP "Salyut", Ufimskoye engine-building association(UMPO).
The IPA method is used to process:

gears (MZKT)

gears and other parts (MAZ)

large (over 800 mm) diameter gears (BelAZ)

intake and exhaust valves (AvtoVAZ)

crankshafts (KAMAZ)

As the world experience in using ion plasma nitriding technology shows, economic effect its implementation is ensured mainly by reducing the consumption of electricity and working gases, reducing the labor intensity of manufacturing products due to a significant reduction in the volume of grinding work, and improving product quality.

With regard to cutting and stamping tools, the economic effect is achieved by reducing its consumption due to an increase in its wear resistance by 4 or more times with a simultaneous increase in cutting conditions.

For some products, ion plasma nitriding is the only way to obtain finished product with a minimum percentage of defects.

In addition, the IPA process ensures complete environmental safety.

Ion plasma nitriding can be used in production instead of liquid or gas nitriding, carburization, nitrocarburization, and high-frequency hardening.

Ion plasma nitriding (IPA) is a modern strengthening method of chemical-thermal treatment of products made of cast iron, carbon, alloy and tool steels, titanium alloys, metal ceramics, and powder materials. High efficiency technology is achieved by using different gas media that influence the formation of a diffusion layer of different composition depending on specific requirements to its depth and surface hardness.

Nitriding using the ion-plasma method is relevant for processing loaded parts operating in aggressive environments subject to friction and chemical corrosion, therefore widely used in the engineering industry, including machine tool building, auto and aviation industry, as well as in the oil and gas, fuel and energy and mining sectors, tool and high-precision manufacturing.

In the process of surface treatment by ion nitriding, the surface characteristics of metals and the operational reliability of critical parts of machines, engines, machine tools, hydraulics, precision mechanics and other products are improved: fatigue and contact strength, surface hardness and resistance to cracking are increased, wear and tear resistance, heat and corrosion resistance.

Advantages of ion plasma nitriding

IPA technology has a number of undeniable advantages, the main one of which is stable processing quality with minimal variation in properties. Controlled gas diffusion and heating process ensures uniform coverage High Quality, given phase composition and structure.

• High surface hardness of nitrided parts.
• No deformation of parts after processing and high surface cleanliness.
• Reducing the processing time of steel by 3-5 times, titanium alloys by 5-10.
• Increasing the service life of a nitrided surface by 2-5 times.
• Possibility of processing blind and through holes.

The low-temperature regime eliminates structural transformations of steel, reduces the likelihood of fatigue failures and damage, and allows cooling at any speed without the risk of martensite. Treatment at temperatures below 500 °C is especially effective in strengthening products made from alloyed tool, high-speed and maraging steels: their performance properties increase without changing the hardness of the core (55-60 HRC).

The environmentally friendly method of ion plasma nitriding prevents bending and deformation of parts while maintaining the original surface roughness within Ra=0.63...1.2 microns - that is why IPA technology is effective as a finishing treatment.

Process technology

Installations for IPA operate in a rarefied atmosphere at a pressure of 0.5-10 mbar. The chamber, operating on the principle of a cathode-anode system, is supplied with ionized gas mixture. A glow pulse discharge is formed between the workpiece being processed and the walls of the vacuum chamber. The active medium created under its influence, consisting of charged ions, atoms and molecules, forms a nitrided layer on the surface of the product.

The composition of the saturating medium, temperature and duration of the process affect the depth of penetration of nitrides, causing a significant increase in the hardness of the surface layer of products.

Ionic nitriding of parts

Ion nitriding is widely used to harden machine parts, working tools and technological equipment of unlimited sizes and shapes: gear rims, crankshafts and camshafts, bevel and cylindrical gears, extruders, couplings of complex geometric configurations, screws, cutting and drilling tools, mandrels, dies and punches for stamping, molds.

For a number of products (large-diameter gears for heavy-duty vehicles, excavators, etc.), IPA is the only way to obtain finished products with a minimum percentage of defects.

Properties of products after hardening using the IPA method

Hardening of gears using the ion nitriding method increases the endurance limit of teeth during bending fatigue tests to 930 MPa, significantly reduces the noise characteristics of machine tools and increases their competitiveness in the market.

Ion plasma nitriding technology is widely used to harden the surface layer of molds used in injection molding: the nitrided layer prevents metal from sticking in the liquid jet supply zone, and the mold filling process becomes less turbulent, which increases the service life of the molds and ensures high quality casting.

Ion plasma nitriding increases the wear resistance of stamping and cutting tools made from steel grades R6M5, R18, R6M5K5, R12F4K5 and others by 4 or more times, with a simultaneous increase in cutting conditions. The nitrided surface of the tool, due to the reduced coefficient of friction, ensures easier removal of chips and also prevents chips from sticking to the cutting edges, which allows increasing feed and cutting speed.

The Ionmet company provides services for surface hardening of structural materials various types parts and tools using ion plasma nitriding - a correctly selected mode will allow you to achieve the required technical indicators hardness and depth of the nitrided layer will ensure high consumer properties of the product.

• Strengthening the surface layer of fine- and coarse-module gears, crankshafts and camshafts, guides, bushings, sleeves, screws, cylinders, molds, axles, etc.
• Increased resistance to cyclic and pulsating loads of crankshafts and camshafts, tappets, valves, gears, etc.
• Increasing wear resistance and corrosion resistance, reducing metal adhesion when casting molds, press and hammer dies, punches for deep drawing, dies.

The nitriding process takes place in modern automated installations:

• table Ø 500 mm, height 480 mm;
• Table Ø 1000 mm, height 1400 mm.

You can check the full range of products for hardening treatment, as well as the possibility of nitriding large parts with complex geometry, from the specialists of the Ionmet company. For determining technical specifications nitriding and start cooperation, send us a drawing, indicate the steel grade and an approximate technology for manufacturing parts.

Ion-plasma hardening Vacuum ion-plasma methods for hardening the surfaces of parts include the following processes: generation (formation) of a corpuscular flow of matter; its activation, acceleration and focusing; ; condensation and penetration into the surface of parts (substrates). Generation: a corpuscular flow of a substance is possible by its evaporation (sublimation) and sputtering. Evaporation: the transition of the condensed phase into steam occurs as a result of the supply of thermal energy to the evaporated substance. Solids usually melt when heated and then change into a gaseous state. Some substances pass into a gaseous state without passing through the liquid phase. This process is called sublimation. .

Using vacuum ion-plasma technology methods, it is possible to perform: 1) modification of surface layers: ion-diffusion saturation; (ionic nitriding, carburization, boronation, etc.); ion (plasma) etching (cleaning); ion implantation (implementation); annealing in a glow discharge; CTO in a non-self-sustaining discharge environment; 2) coating: polymerization in a glow discharge; ion deposition (triode sputtering system, diode sputtering system, using a discharge in a hollow cathode); electric arc evaporation; ion-cluster method; cathode sputtering (on DC, high frequency); chemical deposition in glow discharge plasma.

Advantages of vacuum ion-plasma hardening methods: high adhesion of the coating to the substrate; uniform coating thickness over a large area; varying the composition of the coating over a wide range, within one technological cycle; obtaining high cleanliness of the coating surface; ecological cleanliness of the production cycle.

Ion sputtering Ion sputters are divided into two groups: plasma-ion sputters, in which the target is located in a gas-discharge plasma created using a glow, arc and high-frequency discharge. Sputtering occurs as a result of bombardment of a target with ions extracted from the plasma; autonomous sources without focusing and with focusing of ion beams bombarding a target.

Basic spray system 1 - chamber; 2 — substrate holder; 3 - parts (substrates); 4 - target; 5 - cathode; 6 — screen; 7 - supply of working gas; 8 - power supply; 9 - pumping.

Chemical treatment in a glow discharge environment Diffusion installations with a glow discharge are used to carry out processes of nitriding, carburization, siliconization and other types of chemical treatment from the gas phase. The depth of the diffusion layer reaches several millimeters with uniform saturation of the entire surface of the product. The process is carried out at a reduced pressure of 10 -1 – 10 -3 Pa, which ensures the existence of a glow discharge. Advantages of using a glow discharge: high energy utilization rate (consumption only for gas ionization and heating of the part); reducing the duration of the process due to rapid heating to saturation temperature; increasing the activity of the gaseous medium and surface layer; the possibility of obtaining coatings from refractory metals, alloys and chemical compounds. Disadvantages of the process: low pressure in the chamber (10 -1 Pa), low productivity, operation in batch mode, inability to process long products (for example, pipes), significant energy consumption high price installations.

Ion-diffusion saturation Advantages over the conventional gas nitriding process: reduction in cycle duration by 3-5 times; reducing the deformation of parts by 3-5 times; the ability to carry out controlled nitriding processes to obtain layers with a given composition and structure; the possibility of reducing the temperature of the nitriding process to 350 -400 0 C, which avoids softening of the core materials of the products; reducing the fragility of the layer and increasing its performance characteristics; ease of protecting individual parts of parts from nitriding; eliminating the danger of a furnace explosion; decline specific costs electrical energy 1.5 -2 times and working gas 30 -50 times; improving working conditions for thermal workers. Disadvantages: the impossibility of accelerating the process by increasing the ion flux density, since as a result of overheating of the parts, the surface hardness decreases; intensification of the ion nitriding process; overlay magnetic field in order to increase current density and reduce gas pressure; by creating the surface of a part with a given defectiveness (preliminary plastic deformation, heat treatment).

Installation of ion cementation EVT

Ion cementation Ion cementation creates a high carbon concentration gradient in the boundary layer. The growth rate of the carburized layer of material is 0.4... 0.6 mm/h, which is 3... 5 times higher than this figure for other cementation methods. The duration of ion cementation to obtain a layer with a thickness of 1... 1.2 mm is reduced to 2... 3 hours. Due to low gas and energy consumption and short processing times production costs decrease by 4...5 times. The technological advantages of ion carburization include high uniformity of carburization, absence of external and internal oxidation, and reduced warping of parts. Volume machining reduced by 30%, number technological operations is reduced by 40%, the duration of the processing cycle is reduced by 50%.

Ion plasma nitriding (IPA) IPA is a type of chemical-thermal treatment of machine parts, tools, stamping and casting equipment, ensuring diffusion saturation of the surface layer of steel (cast iron) with nitrogen or nitrogen and carbon in a nitrogen-hydrogen plasma at a temperature of 450 - 600 ° C , as well as titanium or titanium alloys at a temperature of 800 – 950 ° C in nitrogen plasma. The essence of ion plasma nitriding is that in a nitrogen-containing gas environment discharged to 200–1000 Pa between the cathode, on which the workpieces are located, and the anode, whose role is played by the walls of the vacuum chamber, an anomalous glow discharge is excited, forming an active medium (ions, atoms, excited molecules). This ensures the formation of a nitrided layer on the surface of the product, consisting of an outer nitride zone with a diffusion zone located underneath it.

Microstructure of the nitrided layer tool steel 4 X 5 MFS a b Microstructures of steels U 8 (a) and 20 X 13 (b) after ion-plasma nitriding

Installation UA-63 -950/3400 with variable geometry of the working chamber (height 1.7 or 3.4 m)

Using the ion plasma nitriding method, the following products are processed by this method: injectors for passenger cars, automatic drive support plates, dies, punches, dies, molds (Daimler Chrysler); springs for injection system (Opel); crankshafts (Audi); camshafts (Volkswagen); crankshafts for compressors (Atlas, USA and Wabco, Germany); gears for BMW (Handl, Germany); bus gears (Voith); strengthening of pressing tools in the production of aluminum products (Nughovens, Scandex, John Davis, etc.). There is positive experience in the industrial use of this method in the CIS countries: Belarus - MZKT, MAZ, Bel. AZ; Russia - Auto. VAZ, Kam. AZ, MMPP "Salyut", Ufa Engine-Building Association (UMPO). The following are processed using the IPA method: gears (MZKT); gears and other parts (MAZ); gears of large (more than 800 mm) diameter (Bel. AZ); intake and exhaust valves (Auto. VAZ); crankshafts (Kam. AZ).

Metallization of products according to type 1 is carried out for decorative purposes, to increase hardness and wear resistance, and to protect against corrosion. Due to the weak adhesion of the coating to the substrate, this type of metallization is not advisable for parts operating under conditions of high loads and temperatures. Metallization technology of types 1 and 2 a involves applying a layer of a substance to the surface of a cold or heated product to relatively low temperatures. These types of metallization include: electrolytic (electroplating); chemical; gas-flame coating processes (spraying); application of coatings by cladding (mechano-thermal); diffusion, immersion in molten metals. Metallization technology of type 2 b involves diffusion saturation of the surface of parts heated to high temperatures with metal elements, as a result of which an alloy is formed in the diffusion zone of the element (Diffusion metallization). In this case, the geometry and dimensions of the metallized part practically do not change.

Ion-plasma metallization Ion-plasma metallization has a number of significant advantages compared to other types of metallization. Heat plasmas and a neutral environment make it possible to obtain coatings with greater structural homogeneity, less oxidation, higher cohesive and adhesive properties, wear resistance, etc., compared to these properties of other types of metallization. Using this metallization method, you can spray various refractory materials: tungsten, molybdenum, titanium, etc. hard alloys, as well as oxides of aluminum, chromium, magnesium, etc. Coating can be applied by spraying both wire and powder. Metallization itself consists of three processes: melting hard metal wire or powder (with ion plasma metallization), spraying molten metal and forming a coating. The materials for spraying can be any refractory metals in the form of wire or powder, but medium-carbon alloyed wires such as Np-40, Np-ZOKHGSA, Np-ZKh 13, etc. can also be used. In the conditions of automobile repair enterprises, an alloy of the type can be used as a refractory material VZK (stellite) or sormite, which has high wear resistance and corrosion resistance.

ION-PLASMA NITRIDING AS ONE OF THE MODERN METHODS FOR SURFACE HARDENING OF MATERIALS

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Improving the quality of metal and its mechanical properties– this is the main way to increase the durability of parts and one of the main sources of saving steel and alloys. The quality and durability of products are improved through a rational choice of materials and hardening methods while achieving high technical and economic efficiency. There are many different methods of surface hardening - hardening with high-frequency currents, plastic deformation, chemical-thermal treatment (CHT), laser and ion-plasma treatment.

The gas nitriding process, traditionally used in industry, as one of the types of chemical treatment, is the process of diffusion saturation of the surface layer of steel with nitrogen. Nitriding can be used with great effect to increase wear resistance, hardness, fatigue strength, corrosion and cavitation resistance of various materials (structural steels, heat-resistant steels and alloys, non-magnetic steels, etc.). It has a number of undeniable advantages, such as: relative simplicity of the process , the possibility of using universal equipment and devices for laying parts, the possibility of nitriding parts of any size and shape. At the same time, gas nitriding also has a number of disadvantages: a long process duration (20-30 hours) even when nitriding to small layer thicknesses (0.2-0.3 mm); the process is difficult to automate; local protection of surfaces that are not subject to nitriding is difficult; application of various galvanic coatings (copper plating, tinning, nickel plating, etc.) requires the organization of special production.

One of the areas of production intensification is the development and implementation of industrial enterprises new promising processes and technologies that improve the quality of products, reduce labor costs for their production, increase labor productivity and improve sanitary and hygienic conditions in production.

Such a progressive technology is ion plasma nitriding (IPA) - a type of chemical-thermal treatment of machine parts, tools, stamping and casting equipment, ensuring diffusion saturation of the surface layer of steel and cast iron with nitrogen (nitrogen and carbon) in a nitrogen-hydrogen plasma at a temperature
400-600ºС, titanium and titanium alloys at a temperature of 800-950 ºС in nitrogen-containing plasma. This process is currently widespread in all economically developed countries: the USA, Germany, Switzerland, Japan, England, France.

In many cases, ion nitriding is more appropriate than gas nitriding. The advantages of IPA in glow discharge plasma include the following: the ability to control the saturation process, which ensures the production of a high-quality coating with a given phase composition and structure; ensuring absolutely identical activity of the gaseous medium over the entire surface of the part covered by the glow discharge, this ultimately ensures the production of a nitrided layer of uniform thickness; reducing the labor intensity of local protection of surfaces that are not subject to nitriding, which is carried out with metal screens; a sharp reduction in the duration of nitriding of parts (2-2.5 times); reduction of parts deformation. The use of IPA instead of carburization, nitrocarburization, gas or liquid nitriding, volumetric or high-frequency hardening allows you to save capital equipment and production space, reduce machine tool and transportation costs, and reduce the consumption of electricity and active gaseous media.

The essence of the ion nitriding process is as follows. In a closed evacuated space between the part (cathode) and the furnace casing (anode), a glow discharge is excited. Nitriding is carried out with an anomalous glow discharge, at a high voltage of the order of W. Modern installations ensure the stability of a glow discharge at the boundary of its transition to normal and arc. The principle of operation of arc extinguishing devices is based on a short-term shutdown of the installation when a voltaic arc ignites.

Nitriding increases the corrosion resistance of parts made of carbon and low-alloy steels. Parts that are nitrided to increase surface strength and wear resistance simultaneously acquire properties against corrosion in steam, tap water, alkali solutions, crude oil, gasoline, and polluted atmospheres. Ion nitriding significantly increases the hardness of parts, which is due to highly dispersed nitride precipitation, the quantity and dispersion of which affects the achieved hardness. Nitriding increases the fatigue limit. This is explained, firstly, by an increase in the strength of the surface, and secondly, by the occurrence of residual compressive stresses in it.

The advantages of ion nitriding are most fully realized in large-scale and mass production, when strengthening large batches of similar parts. By varying the gas composition, pressure, temperature and holding time, layers of a given structure and phase composition can be obtained. The use of ion nitriding provides technical, economic and social effects.