Chemical Thermal Treatment Research Articles

Increasing wear resistance of the protective bush-ing of the centrifugal pump made of gray cast iron by chemical-thermal treatment

Problem. The weak link that reduces the warranty time of centrifugal pumps is a unit that includes protective bushings and seals. The purpose of the bushings is to protect the rotor shaft from erosion, corrosion and wear. The bushing works under conditions of abrasive wear by elements of the seal packing and abrasive particles entering the liquid pumped by the pump. Due to accelerated surface wear, cast iron protective bushings do not satisfy the requirements service life. Goal. The purpose of the work is to increase wear resistance of pump parts made of gray cast iron by chemical and thermal treatment. Method. Metallographic studies of the structure were performed under a UIT MicroMet-D-101 microscope. Wear is studied using the roller-pad method on a friction machine. Sulfocyanation of cast iron samples was carried out in molten salts (K2CO3, CO(NH2)2, Na2S at 560°С at the bottom of the bath. Results. In the cast state, the microstructure of gray cast iron consists of ferrite, pearlite, double phosphide eutectic and lamellar graphite inclusions. The influence of exposure time during sulfocyanation in a bath with molten salts on the structure and properties of the formed surface layer was studied. The exposure was carried out for 2 hours, 3 hours 30 minutes and 6 hours. After exposure in the bath, a thin carbonitride layer is formed on the surface of the cast iron, and a layer consisting of iron sulfide is formed on top. Conducting wear tests showed that sulfocyanation increases the wear resistance of gray cast iron. An increase in the wear resistance of cast iron is provided by a hard carbonitride layer, and good workability – by a layer of iron sulfides, which acts as a lubricant. Scientific novelty. Increasing the exposure time during sulfocyanation in the bath for more than 3 hours 30 minutes does not affect the thickness of the carbonitride layer. Practical significance. As an optimal mode of sulfocyanation, exposure for 3 hours 30 minutes can be recommended, which provides a 4.8-fold increase in wear resistance.

Technological Methods of Boriding Products from Stainless Alloys Operating in Aggressive Conditions

Introduction. The durability and other performance characteristics of machine parts are largely determined by physical and chemical state of thin surface layers. The localization of hardening processes in these layers serves as a significant reserve for increasing the service life of parts while reducing the cost of manufacturing materials. One of the most progressive directions of strengthening technology is the application of protective coatings on the working surfaces of machine parts.The article investigates the process of sintering compacts from steel PKh23N18 in boron carbide powder in containers with a fusible seal. It has been established that sintering in such containers provides high mechanical characteristics of sintered steel with good reproducibility of the sintering process.Problem Statement. To improve corrosion resistance, as well as to improve wear resistance of friction surfaces of products and machine parts operating in aggressive environments, it is necessary to choose a rational technology of chemical-thermal treatment that allows increasing the mechanical and technological properties of products.Theoretical Part. As a theoretical description, the use of various methods of stainless steel boriding is analyzed, and the dependences of changes in the mechanical and technological properties of samples on various boriding schemes and methods for obtaining samples are considered.Conclusions. It was established in the work that the increase in strength of samples subjected to boriding sintering in an autonomous gaseous medium occurred due to the absence of oxidation and deep saturation with boron (volumetric strengthening) through the vapor-gas phase. The use of container technology makes it possible not only to simplify the technology, but also to ensure the preservation of material properties, regardless of the presence of a protective gaseous medium in the thermal shop.

EFFECT OF THE JOINT SATURATION CONDITIONS OF STEEL WITH CHROMIUM AND NICKEL ON THE DIFFUSION LAYER DEPTH

The destruction of parts of machines and mechanisms made of carbon and structural steels, as a rule, begins with surface corrosion, which can be prevented by applying protective coatings, in particular, by chemical-thermal treatment. The results of laboratory studies on the joint thermal diffusion saturation of steel 35Х2Н3 with chromium and nickel at a temperature of 1000°C for 24 hours are presented. A technique for analyzing the resulting coating based on the possibilities of X-ray spectral microanalysis (EDXA) of the diffusion layer on transverse microsections of the obtained samples is presented. The elemental composition of the diffusion layer was monitored using a JEOL JSM-6460 LV universal scanning electron microscope. Additionally, an experiment was carried out, which made it possible to fix the occurrence of an electric current in the system due to the thermal emission of electrons from the metals of the saturating mixture. It is shown that the complex saturation of structural steel with chromium and nickel has a favorable effect on the depth of the diffusion layer. An effective way to increase the depth of diffusion of chromium and nickel is to use an electron gun (nickel mesh). The diffusion depth of nickel increases by 2 times and chromium by 1.3 times. The fact of electron emission and the occurrence of their directed flow (current strength up to 0.15 mA) from the backfill to the saturated part has been experimentally confirmed. It was established that the magnitude of the emerging current depends on the number of emitted electrons and it is higher when the work function of electrons for the metal in the filling is lower.

Improving the technology of chemical-thermal treatment of tool steels

The paper presents data on the study of the intensification of chemical-thermal treatment processes. Diffusion saturation of the surface of steels and alloys is most often carried out under high-temperature isothermal or isothermal-step exposure with complete recrystallization of steel into an austenitic state. This leads to overheating — the structure and mechanical properties, in addition to hardness and wear resistance, deteriorate. the main regularities and mechanisms of boration of ferritoperlite steels are investigated and described. It is shown that cyclic heating and cooling significantly accelerate the kinetics of the CTO process of iron-carbon alloys. It was found that thermal cycling during boration leads to an increase in the layer thickness up to 80% on carbon steels, with an increase in the degree of alloying, the effect decreases from 70% (cast steel 5KHNM) to 20% (steel X12M). With an increase in the carbon content in steel, the depth of the borated layer decreases both after isothermal high-temperature boration and after thermocyclic boration.

Effect of Diamond Burnishing on Fatigue Behaviour of AISI 304 Chromium-Nickel Austenitic Stainless Steel.

The disadvantages of widely used austenitic stainless steels are their low hardness and relatively low fatigue strength. Conventional chemical-thermal surface treatments are unsuitable for these steels since they create conditions for inter-granular corrosion. An effective alternative is a low-temperature surface treatment, creating an S-phase within the surface layer, but it has a high cost/quality ratio. Austenitic steels can increase their surface micro-hardness and fatigue strength via surface cold working. When the goal is to increase the rotating bending fatigue strength of austenitic chromium-nickel steels, and the requirements for significant wear resistance are not paramount, diamond burnishing (DB) has significant potential to increase the fatigue strength and, based on the cost/quality ratio, can successfully compete with low-temperature chemical-thermal treatments. The main objective of this study is to establish the effect of DB on the rotating fatigue strength of AISI 304 L chromium-nickel austenitic steel. The influence of DB parameters on the surface integrity (SI) characteristics was studied. Optimal DB parameters under minimum roughness and maximum micro-hardness criteria were obtained. Rotating bending fatigue tests of the diamond burnished (in a different manner) and untreated specimens were performed. DB implemented via parameters providing maximum micro-hardness increased fatigue limit by 38% compared to untreated specimens.

Quality of manufacturing of gears from sparingly alloyed steel at all stages of technological conversion

The advantages of sparingly alloyed steels for the manufacture of large-module gears are substantiated. A test output quality control of the manufacture of gears from rolled new structural sparingly alloyed steel 21ХГНМБА (21KhGNMBA) was carried out at all stages of technological conversion in the conditions of serial production. The efficiency of the developed technological processes of preliminary heat treatment of workpieces and chemical-thermal treatment of gears is shown. A significant reduction in the labor intensity of these processes is achieved in comparison with the processes of chemical-thermal treatment of steels with a high nickel content. Recommendations are given on the choice of an abrasive tool for grinding surface-hardened gears made of economically alloyed steel.

Surfacing of stamping tools with subsequent nitrocarburizing for their effective restoration

The possibility of restoration and hardening of stamping tools by surfacing them with special electrodes OZSh-1 and TsN-4 with subsequent nitrocarburizing is shown. The microstructure of nitrocarburized surfacings on transverse sections was studied using a Quanta 650 FEG microscope by scanning electron microscopy. The dependence of the abrasive wear of the deposited coatings on the carbonitriding temperature has been experimentally established. It has been established that the increased wear resistance of nitrocarburized surfacings is due to the characteristics of the carbonitride structure of the diffusion layers, which depend on the alloying of the deposited metal and on the nitrocarburizing modes. The features of chemical-thermal treatment in a highly active nitrogen-carbon paste, which leads to the formation of diffusion layers with excess carbonitrides having high hardness on the surface of the deposited metal, are considered. The high efficiency of a pasty coating based on amorphous carbon and nitrogencontaining components (urea and potassium ferricyanide) has been experimentally shown. It has been established that for the restoration of small die tools with small allowable wear, it is advisable to use chromium-molybdenum surfacing with an OZSh-1 electrode, nitrocarburized at a temperature of 700 °C, for large-sized dies, manganese surfacing TsN-4. At the same time, carbonitriding of manganese coatings deposited with TsN-4 electrodes must be carried out at a temperature of 900 °C in order to obtain carbonitride layers of great depth on the surface of the restored stamps.

Carbon dots with tunable emission based on pH values

Fluorescent carbon dots are the hot topic of fluorescent nanomaterials due to their outstanding optical properties and promising practical application. However, the drawback of fluorescent carbon dots that their strong emission frequently in the blue-light region restricts their further applications. Here, fluorescent carbon dots with tunable emission were synthesized through a simple, rapid and low-cost chemical thermal treatment method. The fluorescent carbon dots emit bright green, yellow and orange fluorescence with different pH value. This is due to the combined effect of size and surface states of fluorescent carbon dots. Further studies show that the fluorescent carbon dots possess intrinsic horseradish peroxidase-like activity and were successfully applied to directly detect Cr3+.

Impact of Magnetic-Pulse and Chemical-Thermal Treatment on Alloyed Steels’ Surface Layer

The relevant problem is searching for up-to-date methods to improve tools and machine parts’ performance due to the hardening of surface layers. This article shows that, after the magnetic-pulse treatment of bearing steel Cr15, its surface microhardness was increased by 40–50% compared to baseline. In this case, the depth of the hardened layer was 0.08–0.1 mm. The magnetic-pulse processing of hard alloys reduces the coefficient of microhardness variation from 0.13 to 0.06. A decrease in the coefficient of variation of wear resistance from 0.48 to 0.27 indicates the increased stability of physical and mechanical properties. The nitriding of alloy steels was accelerated 10-fold that of traditional gas upon receipt of the hardened layer depth of 0.3–0.5 mm. As a result, the surface hardness was increased to 12.7 GPa. Boriding in the nano-dispersed powder was accelerated 2–3-fold compared to existing technologies while ensuring surface hardness up to 21–23 GPa with a boride layer thickness of up to 0.073 mm. Experimental data showed that the cutting tool equipped with inserts from WC92Co8 and WC79TiC15 has a resistance relative to the untreated WC92Co8 higher by 183% and WC85TiC6Co9—than 200%. Depending on alloy steel, nitriding allowed us to raise wear resistance by 120–177%, boriding—by 180–340%, and magneto-pulse treatment—by more than 183–200%.

Comparison of the tribological parameters of solid lubricating coatings based on molybdenum diselenide, deposited in different ways to parts of friction units, operated under normal atmospheric pressure and in vacuum

The tribological characteristics of solid lubricating coatings (SLC) based on Mo—Se—C by various methods of deposition in vacuum and at normal atmospheric pressure are investigated. It is established that the linear wear rate of SLC of magnetron deposition on DC324 direct current practically coincides with that of VNII NP 212 SLC based on МоS2 of suspension deposition. The coating obtained by chemical-thermal treatment (CTT) with selenium of the molybdenum base is an order of magnitude inferior in this parameter. The friction coefficients of DC324 SLC and МоSe2 CTT are in 2—3 times lower than that of VNII NP 212 SLC of suspension deposition for friction modes corresponding to a surface temperature of 36.5÷59.2 °C. Keywords: solid lubricating coating, tribological indicators, diffusion and magnetron-radio frequency deposition, normal atmospheric pressure, vacuum. chopinp@mail.ru, silyaolya@yandex.ru, grib-vladimir.g@ya.ru

ОБ АНОМАЛЬНЫХ СВОЙСТВАХ ДОМЕННОГО ЧУГУНА БЕЗ ВЫДЕЛЕНИЙ ГРАФИТА

The development of modern materials science provides for the constant search for new materials with higher properties. Expensive iron-nickel alloys, the so-called Invars, are currently widely used as such materials. Speaking about the structure and properties of cast iron, the influence of gases (hydrogen, nitrogen and oxygen) on the formation of its structure and properties is most often ignored. In the practice of obtaining cast iron castings, to impart the desired properties to cast iron, the treatment of the melt with various substances is often used. In addition to affecting the chemical composition of the melt, its properties can be changed using other factors. One of the simplest in implementation and efficiency can be a change in the temperature of the melt and residence time at this temperature. To study the effect of thermal cycling on the linear expansion and microstructure of cast iron, two variants of melt processing were carried out. The first one consisted in heating to 1300 °С, holding for 15 minutes and cooling until a hard crust was obtained. The second one is heated to 1550 °С, held for 15 minutes and cooled to a temperature of 1350 °С. Both processes were repeated many times. The performed processing of the melt completely removes the precipitation of free graphite from the cast iron structure. Metallographic analysis of dilatometric samples made it possible to establish that thermal cycling leads to the formation of ledeburite. The effect of heat treatment on the linear expansion and microstructure of blast furnace iron after pretreatment of the melt was studied. The most effective was the chemical-thermal treatment (carburizing in the environment of the Bonduzhsky carburizer) followed by quenching. Carrying out carburizing in the environment of the Bonduzhsky carburizer leads to an increase in the values of the linear expansion coefficient in the region of low and high test temperatures. However, subsequent quenching allows one to obtain rather low values of the coefficient of linear expansion: 3,1·10–6, deg–1 at a temperature of 150 °С and 1,8·10–6, deg–1 at a temperature of 400 °С. Comparing the coefficient of linear expansion of blast furnace iron without precipitation of graphite with the coefficients of linear expansion of Invars in different temperature ranges, it can be seen that the coefficient of linear expansion after preliminary processing takes on rather low values.

РАСПРЕДЕЛЕНИЕ ХРОМА И ВОЛЬФРАМА В ДИФФУЗИОННОМ СЛОЕ СТАЛИ 35Х2Н3 ПРИ СОВМЕСТНОМ ТЕРМОДИФФУЗИОННОМ НАСЫЩЕНИИ

Chemical-thermal treatment (CHT) of structural parts operating under conditions of wear, friction, shock loads make it possible to obtain a unique combination of surface and core properties of the product. However, such traditional CTO methods as carburizing and nitriding, while improving the mechanical characteristics of the surface, are not suitable for all types of steels. Diffusion metallization methods, in particular, thermal diffusion chromium plating, are more effective in terms of the achieved set of properties. Currently, chromium plating is carried out both by saturation of the metal with one element – chromium, and by multi-element mixtures. The article describes the technology of thermal diffusion saturation of steel X35CrNi2-3 with chromium and tungsten at a temperature of 1000 °С. A technique for analyzing the obtained coating is presented, based on the possibilities of X-ray spectral microanalysis (XMS) of the diffusion layer on transverse microsections of the obtained samples. The elemental composition of the diffusion layer was monitored using a JEOL JSM-6460 LV universal scanning (scanning) electron microscope. The microstructure was studied on an optical metallographic microscope Axio Observer D1.m. X-ray phase analysis was carried out on a Rigaku Ultima IV diffractometer. The hardness measurement was carried out on an FM-800 microhardness tester at a load of 100 g. Data were obtained on the qualitative and quantitative distribution of chromium and tungsten in the surface layer of steel. It is shown that the resulting thermal diffusion coating consists of a substitutional solid solution based on Cr–Fe with a bcc lattice, chromium and tungsten carbides. The depth of the outer coating on the sample was about 20 μm, the depth of the diffusion layer in the base metal was 50–55 μm. The absence of a decarburized area in the surface layer of the base metal was noted. The average diffusion coefficients of chromium in the α-phase of chromium were determined to be DCr = 3,58·10–13 m2/s; in the γ-phase of iron DCr = 2,83·10–15 m2/s. The microhardness of the outer surface layer was 1800–2000 HV, the diffusion layer in the base metal was 1300–550 HV, and the base metal was about 540–510 HV.

ИССЛЕДОВАНИЕ РАСПРЕДЕЛЕНИЯ ХРОМА В ДИФФУЗИОННОМ СЛОЕ ПРИ ХРОМИРОВАНИИ СТАЛИ 35Х2Н3

The analysis of scientific literature has shown the diffusion saturation of two and more chemical elements of the surface of alloys remains understudied due to the complexity of sample preparation and subsequent analysis of samples. This remains a relevant objective of modern science. Using of a new technique for determining the concentration of a chemical element during chemical-thermal treatment of alloys will greatly facilitate the theoretical studying of diffusion processes in alloys and the practical application of diffusion saturation. The article describes a new method of determining the concentration of chromium during diffusion chromium plating of steel. The possibilities of the new technique are shown on the example of diffusion saturation with chromium of X35CRNI2-3. The principle of the technique – the obtained samples after chromium plating of steel are cut across the axis, thin sections are made, the diffusion layer is examined from the end of the sample using an electron microscope. In this work the analysis technique is based on the capabilities of scanning electron microscopy, X-ray spectral microanalysis of diffusion layers across a section (local determination of the chemical composition of the material). The chemical composition of the diffusion layer was monitored using a universal scanning electron microscope JEOL JSM-6460 LV. Chromium diffusion saturation of steel X35CRNI2-3 has done. A dense (pore-free) surface layer containing 100 to 2% chromium, to 62 microns thick, has obtained. The diffusion coefficient of chromium has calculated: α-phase – DCr = 6.3·10–14 m2/s, γ-phase – DCr = 3.7·10–15 m2/s. The microhardness of the chromiumplated layer has determined, which averaged 1369 HV300.

РАСПРЕДЕЛЕНИЕ ХРОМА И ВАНАДИЯ В ДИФФУЗИОННОМ СЛОЕ СТАЛИ 35Х2Н3 ПРИ СОВМЕСТНОМ ТЕРМОДИФФУЗИОННОМ НАСЫЩЕНИИ

Termodiffusion saturation of the surface of alloys with two or more elements remains poorly understood despite the great practical and scientific interest that this method of chemical-thermal treatment represents. The simultaneous introduction of several elements can significantly reduce the processing time of products and obtain a multiphase composition on the surface of the product, which opens up wide opportunities for imparting unique technological and operational properties to products. The article describes the features of the distribution of chromium and vanadium during joint thermal diffusion saturation of steel X35CrNi2-3 at a temperature of 1000 °C. The proposed analysis technique is based on the possibilities of X-ray spectral microanalysis of diffusion layers on transverse microsections of the obtained samples. The elemental composition of the diffusion layer was monitored using a JEOL JSM-6460 LV universal scanning electron microscope. The microstructure was studied on an optical metallographic microscope Axio Observer D1.m. X-ray phase analysis was carried out on a Rigaku Ultima IV diffractometer. The hardness measurement was carried out on an FM-800 microhardness tester at a load of 100 g. Data were obtained on the qualitative and quantitative distribution of chromium and vanadium in the surface layer of steel. It is shown that the emerging diffusion coating has the following structure: a structureless outer layer, consisting mainly of chromium, vanadium carbides → a region of columnar crystals (experiencing γ→α transformation upon cooling), consisting mainly of their Cr1.0V0.4Fe0.3 solid solution → partially decarburized α-phase → base metal. The diffusion coefficients of chromium and vanadium are determined: in the α-phase DCr = 1.3·10–15 m2/s; DV = 1.8·10–14 m2/s; in the γ-phase DCr = 1.13·10–15 m2/s; DV = 1.3·10–15 m2/s. The microhardness of the outer surface layer was 1400–1980 H, the diffusion layer in the base metal was 630–790 HV, and the base metal was about 540–510 HV.

РАСПРЕДЕЛЕНИЕ ХРОМА И МОЛИБДЕНА В ДИФФУЗИОННОМ СЛОЕ СТАЛИ 35Х2Н3 ПРИ СОВМЕСТНОМ ТЕРМОДИФФУЗИОННОМ НАСЫЩЕНИИ

Known methods of chemical-thermal treatment of structural parts, such as carburizing, nitriding, diffusion metallization technologies, make it possible to obtain a unique combination of surface and core properties of the product. The positive experience of using methods of multi-element diffusion saturation opens up prospects for the development of methods for complex saturation. The article describes the technology of thermal diffusion saturation of steel X35CrNi2-3 with chromium and molybdenum at a temperature of 1000 °C. A technique for analyzing the obtained coating is presented, based on the possibilities of X-ray spectral microanalysis (XMS) of the diffusion layer on transverse microsections of the obtained samples. The elemental composition of the diffusion layer was monitored using a JEOL JSM-6460 LV universal scanning (scanning) electron microscope. The microstructure was studied on an optical metallographic microscope Axio Observer D1.m. X-ray phase analysis was carried out on a Rigaku Ultima IV diffractometer. The hardness measurement was carried out on an FM-800 microhardness tester at a load of 100 g. Data were obtained on the qualitative and quantitative distribution of chromium and molybdenum in the surface layer of steel. It is shown that the resulting thermal diffusion coating consists mainly of a substitutional solid solution based on Cr–Fe–Mo with a bcc lattice and chromium and molybdenum carbides. The depth of the outer coating on the sample was about 20 μm, the depth of the diffusion layer in the base metal was about 25 μm. The absence of a decarburized area in the surface layer of the base metal was noted. The average diffusion coefficients of chromium and molybdenum in the α-phase of chromium were determined DCr = 6.6·10–15 m2/s and DMo = 4.35·10–16 m2/s respectively; in the γ-phase of iron DCr = 2.95·10–15 m2/s, DMo = 2.48·10–16 m2/s respectively. The microhardness of the outer surface layer was 1400–1980 H, the diffusion layer in the base metal was 1000–600 HV, and the base metal was about 540–510 HV.

Express method for the testing of tribotechnical properties of lubricants

The paper presents the results of experimental study of the tribotechnical properties of lubricants on a unit that simulates the geometric, kinematic and force similarity of well drilling conditions. Bearings with different radial clearances and the same chemical-thermal treatment were investigated. Data registration was carried out on cathode, loop oscilloscopes and electronic recorders. The load on the bearing, the moment of rolling resistance on the journal, and the angular speed of rotation of the outer race were recorded. The temperature was registered using artificial and semiartificial thermocouples. A strobotachometer was used to determine the portable speed of the rolling bodies. The external appearance of all rolling elements was investigated, metallographic analysis of thin surface layers of all rolling elements was carried out, mathematical processing of test results was carried out. It is shown that for the express assessment of the tribotechnical properties of lubricants, the amplitude value of the oscillation of the rolling resistance moment can be used. Keywords: friction; lubrication; tribotechnical Properties; drilling.

Increasing the tribological properties of the sur-face layer of cast iron by treatment in the envi-ronment of overheated steam of aqueous solution

The formation of the surface layer of cast iron during the processing of cast iron in the environment of superheated steam of an aqueous solution of salts is considered. An ecologically cleaner method of chemical-thermal treatment is offered. The article considers the surface layer obtained in the environment of superheated steam of an aqueous solution of water-soluble salts of ammonium molybdic acid. The layer is formed on the surface of the matrix and around the graphite inclusions. The impact of temperature on the formation of a multilayer coating by increasing the temperature in contact with the metal surface is the dissociation of chemical compounds in solution, with the formation of atomic oxygen, sulfur, nitrogen, molybdenum. The formation of the surface layer occurred not only on a metal base, but also on the boundaries of graphite, both lamellar and globular, coming to the surface of the metal without breaking the solid layer. It is established that as a result of interaction of technological parameters of temperature, holding time and concentration of saturated medium graphite in the surface layer changes its shape, becoming spherical, although in the matrix it had a lamellar shape. It is multiphase and contains soft and hard structural components. Comparative studies have shown that the wear rate of untreated cast iron is much higher than that of treated cast iron, and reaches 0.8 ∙ 10-4 μm/km at a load of 400 N. This increases the wear resistance of cast iron and at the same time improves the workability reducing the coefficient of friction. The effect of the coating on the workability show that the stabilization of the friction moment occurs faster in samples with a multilayer coating. Thus, for gray cast iron with lamellar graphite, the stabilization time of the friction moment in a multilayer coating is 0.6 h compared with 2 h for a single layer coating; in high-strength cast iron it is, respectively, 5.2 and 6.3 hours.

Increasing the wear and corrosion resistance of steel parts by methods of complex boronikeling and borovolframing

The paper presents ways to increase the wear and corrosion resistance of steel parts by chemical and thermal treatment methods. Comprehensive studies of the structure and properties of St3 steel samples were carried out after simultaneous complex saturation with boron and nickel, boron and tungsten from saturating coatings based on boron carbide. Both compounds of these elements (oxides, carbides, borides) and pure metals were used as suppliers of nickel and tungsten. Studies have shown that multicomponent saturation processes make it possible to form a multiphase structure of a surface layer with a complex of useful properties. Moreover, by chemical-thermal treatment it is possible to obtain such a combination of properties of the hardened product, which cannot be obtained by other methods.

Application of the technology of induction chemical-thermal treatment to improve the physical and mechanical properties of tantalum

The results of the chemical thermal treatment (CTT) of tantalum in a solid carbon- containing medium in the temperature range from 1000 to 1300 °C were presented. CTT consisted in heating a workpiece with a working medium in a container made of a refractory material. The induction heating method was used for heating. After strengthening treatment, tantalum samples were characterized by increased hardness, which grew from 140 to 1100 HV0.02.

Improving the mechanical properties of tool steel by induction chemical-thermal treatment

The study results of the structure and microhardness of the surface layer of high-speed tool steel after induction chemical-thermal treatment in a gaseous nitrogen-containing medium at a temperature of 900–1100 °C were presented. Due to the strengthening treatment of products a gradient diffusion nitride layer with a thickness of about 200 μm and a surface microhardness of 1950±70 HV1 98 was formed.