Pub Date : 2021-12-09DOI: 10.17073/1997-308x-2021-4-38-45
D. D. Nesmelov, E. S. Novoselov, S. S. Ordan’yan
Refractory composite ceramic material in the LaB6–W2B5 system with a component ratio of 50 : 50 vol.% was obtained by reactive hot pressing in a graphite mold. A heterophase powder containing lanthanum hexaboride, metallic tungsten, and amorphous boron preliminarily ball-milled for 20 h with tungsten balls was used as the initial reaction mixture. The average particle size of the milled mixture was 2.9 μm. A relative density of 92 % was achieved at a temperature of 1800 °C with isothermal holding for 15 min at 30 MPa in an argon atmosphere. The structure and composition of the LaB6–W2B5 material were studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The composition of the ceramics contained two phases – cubic LaB6 lanthanum hexaboride and hexagonal W2B5 tungsten pentaboride. The ceramic structure featured by ordered lamellar W2B5 particles in a LaB6 polycrystalline matrix. During the reactive hot pressing of the LaB6–W–B mixture, the predominant growth of W2B5 crystals along (101) atomic planes was observed. Resulting lamellar W2B5 particles were oriented in the LaB6 matrix perpendicular to the pressing load. Images obtained with electron microscopy were used for the three-dimensional visualization of the LaB6–W2B5 structure. Three-point bending tests were conducted on 3×3×30 mm samples. The dependence of bending strength on the direction of applied breaking load was established. When a breaking load was applied perpendicular to the surface of the lamellar W2B5 particles, the ultimate strength was 420 MPa, while when loaded along the plane of the particles, bending strength increases to 540 MPa. The anisotropy coefficient of ultimate strength was 0.78.
{"title":"Anisotropy of the bending strength of LaB6–W2B5 reactive hot-pressed ceramics","authors":"D. D. Nesmelov, E. S. Novoselov, S. S. Ordan’yan","doi":"10.17073/1997-308x-2021-4-38-45","DOIUrl":"https://doi.org/10.17073/1997-308x-2021-4-38-45","url":null,"abstract":"Refractory composite ceramic material in the LaB6–W2B5 system with a component ratio of 50 : 50 vol.% was obtained by reactive hot pressing in a graphite mold. A heterophase powder containing lanthanum hexaboride, metallic tungsten, and amorphous boron preliminarily ball-milled for 20 h with tungsten balls was used as the initial reaction mixture. The average particle size of the milled mixture was 2.9 μm. A relative density of 92 % was achieved at a temperature of 1800 °C with isothermal holding for 15 min at 30 MPa in an argon atmosphere. The structure and composition of the LaB6–W2B5 material were studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The composition of the ceramics contained two phases – cubic LaB6 lanthanum hexaboride and hexagonal W2B5 tungsten pentaboride. The ceramic structure featured by ordered lamellar W2B5 particles in a LaB6 polycrystalline matrix. During the reactive hot pressing of the LaB6–W–B mixture, the predominant growth of W2B5 crystals along (101) atomic planes was observed. Resulting lamellar W2B5 particles were oriented in the LaB6 matrix perpendicular to the pressing load. Images obtained with electron microscopy were used for the three-dimensional visualization of the LaB6–W2B5 structure. Three-point bending tests were conducted on 3×3×30 mm samples. The dependence of bending strength on the direction of applied breaking load was established. When a breaking load was applied perpendicular to the surface of the lamellar W2B5 particles, the ultimate strength was 420 MPa, while when loaded along the plane of the particles, bending strength increases to 540 MPa. The anisotropy coefficient of ultimate strength was 0.78.","PeriodicalId":14693,"journal":{"name":"Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87761080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-23DOI: 10.17073/1997-308x-2021-2-4-12
N. A. Kochetov, A. Rogachev, D. Kovalev, A. Shchukin, S. Vadchenko
A two-phase powder alloy based on substitutional solid solutions with BCC and FCC lattices was obtained by highintensity mechanical treatment (HMT) of a multicomponent Fe–Cr–Co–Ni–Ti powder mixture. Sample sections and particles of mixtures obtained were studied using an ultra high resolution field emission scanning electron microscope by scanning electron microscopy. XRD patterns of mixtures were recorded on the DRON 3 diffractometer with FeKα and CuKα radiation. It was found that after 10 minutes of HMT one intense superposition reflection remains on the XRD pattern with the angular position corresponding to Reflections 111 and 110 of phases with FCC and BCC lattices, respectively. A spark plasma sintering (SPS) method was used to obtain compact high-entropy material samples from the mixture after 90 minutes of HMT at 800 and 1000 °C. Their specific electrical resistance and density as well as the dependence of these properties on the sintering temperature were determined. It was demonstrated that the substitutional solid solution with the BCC lattice is probably enriched with titanium during the powder alloy SPS process.
{"title":"Production of high-entropy Fe–Cr–Co–Ni–Ti alloy by mechanical alloying and spark plasma sintering of a powder mixture","authors":"N. A. Kochetov, A. Rogachev, D. Kovalev, A. Shchukin, S. Vadchenko","doi":"10.17073/1997-308x-2021-2-4-12","DOIUrl":"https://doi.org/10.17073/1997-308x-2021-2-4-12","url":null,"abstract":"A two-phase powder alloy based on substitutional solid solutions with BCC and FCC lattices was obtained by highintensity mechanical treatment (HMT) of a multicomponent Fe–Cr–Co–Ni–Ti powder mixture. Sample sections and particles of mixtures obtained were studied using an ultra high resolution field emission scanning electron microscope by scanning electron microscopy. XRD patterns of mixtures were recorded on the DRON 3 diffractometer with FeKα and CuKα radiation. It was found that after 10 minutes of HMT one intense superposition reflection remains on the XRD pattern with the angular position corresponding to Reflections 111 and 110 of phases with FCC and BCC lattices, respectively. A spark plasma sintering (SPS) method was used to obtain compact high-entropy material samples from the mixture after 90 minutes of HMT at 800 and 1000 °C. Their specific electrical resistance and density as well as the dependence of these properties on the sintering temperature were determined. It was demonstrated that the substitutional solid solution with the BCC lattice is probably enriched with titanium during the powder alloy SPS process.","PeriodicalId":14693,"journal":{"name":"Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya","volume":"107 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79399310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-23DOI: 10.17073/1997-308x-2021-2-49-59
A. P. Demirov, I. V. Blinkov, D. Kuznetsov, K. Kuskov, E. Kolesnikov, A. Sedegov
The paper studies methods for obtaining a multilevel gradient porous material by the layer-by-layer sintering of distributed α-Fe2O3 nanopowders and submicron powders. Nanopowders with an average particle size of 12 nm were obtained by the coprecipitation method, and submicron powders, which are hollow spheres, were obtained using the spray pyrolysis method. Powders were consolidated by sintering in a muffle furnace, hot pressing, and spark plasma sintering (SPS) at various temperatures, loads, and holding times. It was shown that muffle furnace sintering and hot pressing methods cannot provide a compact of enough strength due to the different activity of nanopowders and submicron powders. Powder materials were obtained by spark plasma sintering when holding at 700, 750, 800, and 900 °С for 3 min. It was found that a series of samples obtained by SPS at 750 °С has sufficient strength and open porosity of 20 % with a total porosity of 37 %. Rising temperature in this method leads to an increase in the particle size in the nanopowder volume to a micron size and partial destruction of hollow submicron spheres. It was found during the study that the phase composition of samples obtained is identical to the phase composition of initial powders. However, for a series of samples obtained by hot pressing and SPS in the nanopowder volume, there is a directed growth of crystals towards the highest electrical and thermal conductivity [001] along the punch axis. This is due to the temperature gradient between the powder volume and punches and the lowest value of the plane surface energy (110), which includes direction [001].
{"title":"Production of α-Fe 2O 3 powder material with multilevel gradient porosity","authors":"A. P. Demirov, I. V. Blinkov, D. Kuznetsov, K. Kuskov, E. Kolesnikov, A. Sedegov","doi":"10.17073/1997-308x-2021-2-49-59","DOIUrl":"https://doi.org/10.17073/1997-308x-2021-2-49-59","url":null,"abstract":"The paper studies methods for obtaining a multilevel gradient porous material by the layer-by-layer sintering of distributed α-Fe2O3 nanopowders and submicron powders. Nanopowders with an average particle size of 12 nm were obtained by the coprecipitation method, and submicron powders, which are hollow spheres, were obtained using the spray pyrolysis method. Powders were consolidated by sintering in a muffle furnace, hot pressing, and spark plasma sintering (SPS) at various temperatures, loads, and holding times. It was shown that muffle furnace sintering and hot pressing methods cannot provide a compact of enough strength due to the different activity of nanopowders and submicron powders. Powder materials were obtained by spark plasma sintering when holding at 700, 750, 800, and 900 °С for 3 min. It was found that a series of samples obtained by SPS at 750 °С has sufficient strength and open porosity of 20 % with a total porosity of 37 %. Rising temperature in this method leads to an increase in the particle size in the nanopowder volume to a micron size and partial destruction of hollow submicron spheres. It was found during the study that the phase composition of samples obtained is identical to the phase composition of initial powders. However, for a series of samples obtained by hot pressing and SPS in the nanopowder volume, there is a directed growth of crystals towards the highest electrical and thermal conductivity [001] along the punch axis. This is due to the temperature gradient between the powder volume and punches and the lowest value of the plane surface energy (110), which includes direction [001].","PeriodicalId":14693,"journal":{"name":"Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya","volume":"195 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76529389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-23DOI: 10.17073/1997-308x-2021-2-60-67
A. Sytchenko, E. Levashov, P. Kiryukhantsev-Korneev
Pulsed magnetron sputtering of a TaSi2 ceramic target 120 mm in diameter was used to deposit coatings on model silicon substrates at a gas flow rate ratio of Ar/N2 = 1/2 and frequencies of 5, 50, and 350 kHz. The structure and composition of coatings were investigated using scanning electron microscopy, energy dispersive analysis and glow discharge optical emission spectroscopy. The phase composition was determined by X-ray diffraction analysis using CuKα radiation. Mechanical properties were measured by the nanoindentation method using a Nano Hardness Tester equipped with a Berkovich indenter at a load of 4 mN. The heat resistance of coatings was evaluated by isothermal annealing in the air in a muffle furnace at 1200 °С, and oxidation resistance was estimated by the structure and thickness of the oxide layer. The results of structure studies have shown that the coatings are X-ray amorphous and have a dense homogeneous structure. Increasing the frequency from 5 to 350 kHz led to a decrease in the thickness and growth rate of the coatings. Samples deposited at 5 and 50 kHz showed high mechanical performance: hardness at the level of 23–24 GPa, elastic modulus of 211–214 GPa, and elastic recovery of 75–77 %. The coating obtained at the maximum frequency had a hardness of 15 GPa, elastic modulus of 138 GPa, and elastic recovery of 65 %. Annealing led to the formation of protective SiO2, Ta2O5, TaO2 oxide layers. A pronounced crystallization of the TaSi2 phase was observed, which is confirmed by the X-ray diffraction analysis data. Samples deposited at 5 and 50 kHz showed a small oxide layer thickness of 0.9 and 1.1 μm, which indicates the good heat resistance of coatings at 1200 °С.
{"title":"Structure and properties of Ta–Si–N coatings obtained by pulsed magnetron sputtering","authors":"A. Sytchenko, E. Levashov, P. Kiryukhantsev-Korneev","doi":"10.17073/1997-308x-2021-2-60-67","DOIUrl":"https://doi.org/10.17073/1997-308x-2021-2-60-67","url":null,"abstract":"Pulsed magnetron sputtering of a TaSi2 ceramic target 120 mm in diameter was used to deposit coatings on model silicon substrates at a gas flow rate ratio of Ar/N2 = 1/2 and frequencies of 5, 50, and 350 kHz. The structure and composition of coatings were investigated using scanning electron microscopy, energy dispersive analysis and glow discharge optical emission spectroscopy. The phase composition was determined by X-ray diffraction analysis using CuKα radiation. Mechanical properties were measured by the nanoindentation method using a Nano Hardness Tester equipped with a Berkovich indenter at a load of 4 mN. The heat resistance of coatings was evaluated by isothermal annealing in the air in a muffle furnace at 1200 °С, and oxidation resistance was estimated by the structure and thickness of the oxide layer. The results of structure studies have shown that the coatings are X-ray amorphous and have a dense homogeneous structure. Increasing the frequency from 5 to 350 kHz led to a decrease in the thickness and growth rate of the coatings. Samples deposited at 5 and 50 kHz showed high mechanical performance: hardness at the level of 23–24 GPa, elastic modulus of 211–214 GPa, and elastic recovery of 75–77 %. The coating obtained at the maximum frequency had a hardness of 15 GPa, elastic modulus of 138 GPa, and elastic recovery of 65 %. Annealing led to the formation of protective SiO2, Ta2O5, TaO2 oxide layers. A pronounced crystallization of the TaSi2 phase was observed, which is confirmed by the X-ray diffraction analysis data. Samples deposited at 5 and 50 kHz showed a small oxide layer thickness of 0.9 and 1.1 μm, which indicates the good heat resistance of coatings at 1200 °С.","PeriodicalId":14693,"journal":{"name":"Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83937777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-23DOI: 10.17073/1997-308x-2021-2-41-48
V. A. Gulevsky
The study covers the process of carbon-graphite – lead composite formation by impregnating a porous AG-1500 scaffold with a lead melt containing 2.0 at.% Cu. The paper describes the kinetics of filling the carbon-graphite open porosity with molten metal with the continuously heated furnace and impregnating device. A feature of this method is the volumetric expansion of the lead alloy impregnating porous carbon-graphite. It is placed in a sealed steel container filled with lead by 2/3 of its volume with further vacuuming, melt adding and sealing. Then the device is placed in the furnace so that the lead-copper alloy, already having a temperature below the liquidus temperature by 20–30 °C when heated in the furnace to 900 °C, impregnates the carbon-graphite scaffold with further expansion at constant heating. Porous scaffold capillaries are filled as the melt temperature continuously increases. Once graphite-carbon impregnated with lead alloy is taken out, it was investigated using X-ray spectral and energy-dispersive analysis. It was found that the elements of the impregnating alloy were redistributed at the carbon-graphite scaffold/Pb alloy interface depending on its initial composition. During the carbon-graphite scaffold impregnation with the Pb–2%Сu alloy under a pressure of up to 5 MPa, copper redistribution occurs on its inner pore surface and the boundary with the alloy, which leads to the formation of an interphase layer containing 70 % Cu. The conducted research made it possible to obtain a composite with a copper content of 1.85 at.% in the impregnating Pb alloy at the interface with carbon graphite.
{"title":"Possibilities of matrix lead alloy doping at non-gasostatic carbon-graphite impregnation","authors":"V. A. Gulevsky","doi":"10.17073/1997-308x-2021-2-41-48","DOIUrl":"https://doi.org/10.17073/1997-308x-2021-2-41-48","url":null,"abstract":"The study covers the process of carbon-graphite – lead composite formation by impregnating a porous AG-1500 scaffold with a lead melt containing 2.0 at.% Cu. The paper describes the kinetics of filling the carbon-graphite open porosity with molten metal with the continuously heated furnace and impregnating device. A feature of this method is the volumetric expansion of the lead alloy impregnating porous carbon-graphite. It is placed in a sealed steel container filled with lead by 2/3 of its volume with further vacuuming, melt adding and sealing. Then the device is placed in the furnace so that the lead-copper alloy, already having a temperature below the liquidus temperature by 20–30 °C when heated in the furnace to 900 °C, impregnates the carbon-graphite scaffold with further expansion at constant heating. Porous scaffold capillaries are filled as the melt temperature continuously increases. Once graphite-carbon impregnated with lead alloy is taken out, it was investigated using X-ray spectral and energy-dispersive analysis. It was found that the elements of the impregnating alloy were redistributed at the carbon-graphite scaffold/Pb alloy interface depending on its initial composition. During the carbon-graphite scaffold impregnation with the Pb–2%Сu alloy under a pressure of up to 5 MPa, copper redistribution occurs on its inner pore surface and the boundary with the alloy, which leads to the formation of an interphase layer containing 70 % Cu. The conducted research made it possible to obtain a composite with a copper content of 1.85 at.% in the impregnating Pb alloy at the interface with carbon graphite.","PeriodicalId":14693,"journal":{"name":"Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84360632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-17DOI: 10.17073/1997-308x-2021-3-34-42
Yu. V. Bogatov, V. Shcherbakov
The paper presents the results of a study on the dense titanium carbide production by SHS compaction. It is shown that the use of a mechanically activated reaction mixture of titanium and carbon black powders makes it possible to obtain titanium carbide samples with a maximum relative density of 95 %. A feature of this research is that the mechanical activation of components and Ti + C mixture stirring were carried out in a ball mill. The study covers the influence of process parameters on the combustion properties and structure of the consolidated titanium carbide. It was found that the high-speed reaction mixture combustion is an essential condition for dense titanium carbide production. It was shown that the burning rate and temperature strongly depend on the size, mass and density of charge compacts. With an increase in the diameter (20–58 mm) and weight (10–70 g) of compacts made of mixtures with activated reagents, the burning rate varied from 10 to 100 cm/s, and the burning temperature varied from 2200 to 3100 °C. An influence of the pre-pressing pressure (applied at the combustion stage) on the burning rate and temperature was shown: the burning rate sharply decreases from 100 to 10 cm/s at pressures between 0 and 10 MPa, and the combustion temperature decreases monotonically from 3000 to 2000 °C at pressures between 0 and 40 MPa. A high-speed combustion mechanism was proposed for the titanium and carbon black reaction mixture where the formation of radial (longitudinal) cracks in compacts pressed from the mechanically activated mixture is an important factor. These cracks ensure the propagation of incandescent impurity gases and the exothermic reaction initiation in the sample volume.
{"title":"Effect of mechanical activation and combustion parameters on titanium carbide SHS compaction","authors":"Yu. V. Bogatov, V. Shcherbakov","doi":"10.17073/1997-308x-2021-3-34-42","DOIUrl":"https://doi.org/10.17073/1997-308x-2021-3-34-42","url":null,"abstract":"The paper presents the results of a study on the dense titanium carbide production by SHS compaction. It is shown that the use of a mechanically activated reaction mixture of titanium and carbon black powders makes it possible to obtain titanium carbide samples with a maximum relative density of 95 %. A feature of this research is that the mechanical activation of components and Ti + C mixture stirring were carried out in a ball mill. The study covers the influence of process parameters on the combustion properties and structure of the consolidated titanium carbide. It was found that the high-speed reaction mixture combustion is an essential condition for dense titanium carbide production. It was shown that the burning rate and temperature strongly depend on the size, mass and density of charge compacts. With an increase in the diameter (20–58 mm) and weight (10–70 g) of compacts made of mixtures with activated reagents, the burning rate varied from 10 to 100 cm/s, and the burning temperature varied from 2200 to 3100 °C. An influence of the pre-pressing pressure (applied at the combustion stage) on the burning rate and temperature was shown: the burning rate sharply decreases from 100 to 10 cm/s at pressures between 0 and 10 MPa, and the combustion temperature decreases monotonically from 3000 to 2000 °C at pressures between 0 and 40 MPa. A high-speed combustion mechanism was proposed for the titanium and carbon black reaction mixture where the formation of radial (longitudinal) cracks in compacts pressed from the mechanically activated mixture is an important factor. These cracks ensure the propagation of incandescent impurity gases and the exothermic reaction initiation in the sample volume.","PeriodicalId":14693,"journal":{"name":"Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya","volume":"9 16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79822899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-17DOI: 10.17073/1997-308x-2021-3-43-61
V. Sanin, M. I. Aheiev, Y. Kaplanskii, M. Petrzhik
A centrifugal SHS casting technology was used to obtain NiAl–Cr–Co–(X) alloys where X = 2.5÷15.0 wt.% Mo and up to 1.5 wt% Re. The study covers the effect of modifying additives on the combustion process as well as the phase composition, structure, and properties of cast alloys. Alloying up to 15 % Mo and 1.5 % Re provided the highest improvement of properties in relation to the base alloy in terms of overall performance. Molybdenum formed a plastic matrix and improved strength properties to the following values: uniaxial compressive strength σucs = 1730±30 MPa, yield strength σys = 1560±30 MPa, plastic component of deformation εpd = 0.95 %, and annealing at t = 1250 °С improved them to: σucs = 1910±80 MPa, σys = 1650±80 MPa, εpd = 2.01 %. Rhenium modified the alloy structure and improved its properties to: σucs = 1800±30 MPa, σys = 1610±30 MPa, εpd = 1.10 %, and annealing further improved them to: σucs = 2260±30 MPa, σys = 1730±30 MPa, εpd = 6.15 %. The mechanical properties of the NiAl, (Ni,Cr,Co)3Mo3C, Ni3Al, (Cr, Mo) and MoRe2 phases, as well as the hypothetical Al(Re,Ni)3 phase, were determined by the nanoindentation method. According to the Guinier–Preston structural transformation, local softening upon annealing at t > 850 °С increases the proportion of plastic deformation during compression tests due to the lost coherence of the boundaries of nanosized plate-shaped Cr-based precipitates with a supersaturated solid solution. A hierarchical three-level structure of the NiAl–Cr– Co–15%Mo alloy was established: the first level is formed by β-NiAl dendritic grains with interlayers of molybdenum-containing phases (Ni,Co,Cr)3Mo3C and (Mo0.8Cr0.2)xBy with a cell size of up to 50 μm; the second one consists of strengthening submicron Cr(Mo) particles distributed along grain boundaries; the third one is coherent nanoprecipitates of Cr(Mo) (10–40 nm) in the body of β-NiAl dendrites. The cast alloy mechanical grinding techniques were used to obtain a precursor powder with an average particle size of Dav = 33.9 μm for subsequent spheroidization.
{"title":"Influence of molybdenum and rhenium alloying additives on NiAl–Cr–Co cast alloy structure and properties","authors":"V. Sanin, M. I. Aheiev, Y. Kaplanskii, M. Petrzhik","doi":"10.17073/1997-308x-2021-3-43-61","DOIUrl":"https://doi.org/10.17073/1997-308x-2021-3-43-61","url":null,"abstract":"A centrifugal SHS casting technology was used to obtain NiAl–Cr–Co–(X) alloys where X = 2.5÷15.0 wt.% Mo and up to 1.5 wt% Re. The study covers the effect of modifying additives on the combustion process as well as the phase composition, structure, and properties of cast alloys. Alloying up to 15 % Mo and 1.5 % Re provided the highest improvement of properties in relation to the base alloy in terms of overall performance. Molybdenum formed a plastic matrix and improved strength properties to the following values: uniaxial compressive strength σucs = 1730±30 MPa, yield strength σys = 1560±30 MPa, plastic component of deformation εpd = 0.95 %, and annealing at t = 1250 °С improved them to: σucs = 1910±80 MPa, σys = 1650±80 MPa, εpd = 2.01 %. Rhenium modified the alloy structure and improved its properties to: σucs = 1800±30 MPa, σys = 1610±30 MPa, εpd = 1.10 %, and annealing further improved them to: σucs = 2260±30 MPa, σys = 1730±30 MPa, εpd = 6.15 %. The mechanical properties of the NiAl, (Ni,Cr,Co)3Mo3C, Ni3Al, (Cr, Mo) and MoRe2 phases, as well as the hypothetical Al(Re,Ni)3 phase, were determined by the nanoindentation method. According to the Guinier–Preston structural transformation, local softening upon annealing at t > 850 °С increases the proportion of plastic deformation during compression tests due to the lost coherence of the boundaries of nanosized plate-shaped Cr-based precipitates with a supersaturated solid solution. A hierarchical three-level structure of the NiAl–Cr– Co–15%Mo alloy was established: the first level is formed by β-NiAl dendritic grains with interlayers of molybdenum-containing phases (Ni,Co,Cr)3Mo3C and (Mo0.8Cr0.2)xBy with a cell size of up to 50 μm; the second one consists of strengthening submicron Cr(Mo) particles distributed along grain boundaries; the third one is coherent nanoprecipitates of Cr(Mo) (10–40 nm) in the body of β-NiAl dendrites. The cast alloy mechanical grinding techniques were used to obtain a precursor powder with an average particle size of Dav = 33.9 μm for subsequent spheroidization.","PeriodicalId":14693,"journal":{"name":"Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya","volume":"06 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86104996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-17DOI: 10.17073/1997-308x-2021-3-62-70
H. Alwan, A. Makarov, N. Soboleva, Y. Korobov, V. Shumyakov, N. Lezhnin, V. Zavalishin
Many machinery parts working in contact with a fast-flowing fluid flow (e.g. turbine blades of hydroelectric power plants, valves, pump impeller blades, ship propellers, cooling systems for various units, etc.) are subjected to such type of wear as cavitation erosion. An important objective is to eliminate or reduce cavitation erosion so as to achieve a considerable economic effect. This research uses a patented technique developed to evaluate the cavitation erosion resistance of cermet thermal spray coatings (WC–10Co4Cr and WC–20CrC–7Ni). These coatings were prepared using high velocity air fuel thermal spraying (HVAF). The aim of this study is to test a new technique for evaluating coating cavitation resistance, which differs from the standard one by specimen positioning relative to the testing liquid. In addition, scanning electron microscopy (SEM) was used to analyze the initial structure of the coatings prepared and study their behavior after cavitation exposure. The material volume loss criterion during the cavitation test was used to evaluate the coating resistance. The results of cavitation tests showed that the WC–20CrC–7Ni coating has a somewhat higher cavitation resistance than that of WC–10Co4Cr despite its slightly lower average hardness (850±90 HV0.5 versus 950±60 HV0.5). The study of coating surfaces and cross-sections showed that they feature by different erosion mechanisms. It can be concluded that the presence of defects (pores) in the coating structure is the main reason for reducing their cavitation erosion resistance. Therefore, the developed technique proved effective in obtaining experimental data to analyze cermet thermal spray coatings for cavitation wear.
许多与快速流动的流体接触的机械部件(如水电站的涡轮叶片，阀门，泵叶轮叶片，船舶螺旋桨，各种装置的冷却系统等)都会受到这种类型的磨损，如空化侵蚀。一个重要的目标是消除或减少空化侵蚀，以达到相当大的经济效果。本研究采用了一项专利技术来评估金属陶瓷热喷涂涂层(WC-10Co4Cr和WC-20CrC-7Ni)的抗空化侵蚀性能。这些涂层采用高速空气燃料热喷涂(HVAF)制备。本研究的目的是测试一种新的方法来评估涂层的空化阻力，它不同于标准的方法，即通过试样相对于测试液体的定位来评估涂层的空化阻力。此外，利用扫描电子显微镜(SEM)分析了所制备涂层的初始结构，并研究了空化暴露后涂层的行为。采用空化试验时的材料体积损失准则评价涂层的耐蚀性。空化试验结果表明，WC-20CrC-7Ni涂层的抗空化能力略高于WC-10Co4Cr涂层，但其平均硬度略低于WC-10Co4Cr涂层(850±90 HV0.5 vs 950±60 HV0.5)。对涂层表面和截面的研究表明，它们具有不同的侵蚀机制。结果表明，涂层结构中存在缺陷(孔隙)是导致涂层抗空化侵蚀性能降低的主要原因。因此，所开发的技术对于获得分析金属陶瓷热喷涂涂层空化磨损的实验数据是有效的。
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Pub Date : 2021-09-17DOI: 10.17073/1997-308x-2021-3-4-13
M. P. Kuz’min, V. Kondratiev, A. S. Kuz’mina, A. Burdonov, Jiangtao Ran
The volume of silicon waste generated annually in the Irkutsk Region is 20 thousand tons per year, and the volume of waste accumulated in three sludge fields of JSC «Silicon» exceeds 3 million m3. The main type of crystalline silicon production waste is dust from gas cleaning systems of electric ore smelting furnaces. In this regard, this paper studies its chemical composition and the possibilities of using valuable components (amorphous silica, carbon nanotubes (CNT)) included in its composition. The study demonstrates that it is possible to separate this product by flotation into 3 components — sand fraction, flotation tailings enriched in SiO2, and froth enriched in carbon in the form of CNT. The structure of carbon nanotubes was studied and their physical and mechanical properties were determined: elastic modulus (2000 GPa), tensile strength (75 GPa), and thermal conductivity (4000 W/(m·K)). The amount of heat required to obtain 1 kg of CNT in electric ore smelting furnaces was calculated. Based on the material balance of commercial silicon electric smelting, it was found that 153 kg of CNT and 336 kg of flotation tailings are formed per ton of crystalline silicon during the endothermic process. Flotation tailings consist of 75 % amorphous microsilica particles. According to heat effect and Gibbs energy calculations made for amorphous microsilica formation reactions, it was found that all processes are exothermic, and the process of solid silicon carbide particles (2SiC + 3O2 → 2SiO2 + 2CO) oxidation with air oxygen has the highest thermodynamic probability. The economic efficiency of using amorphous silica to produce casting silumins was calculated, and its results clearly demonstrate a quick payback period (6 months), as well as a high level of its profitability (USD 819672).
{"title":"Formation of carbon nanotubes and microsilica when obtaining crystalline silicon in three-phase electric ore smelting furnaces","authors":"M. P. Kuz’min, V. Kondratiev, A. S. Kuz’mina, A. Burdonov, Jiangtao Ran","doi":"10.17073/1997-308x-2021-3-4-13","DOIUrl":"https://doi.org/10.17073/1997-308x-2021-3-4-13","url":null,"abstract":"The volume of silicon waste generated annually in the Irkutsk Region is 20 thousand tons per year, and the volume of waste accumulated in three sludge fields of JSC «Silicon» exceeds 3 million m3. The main type of crystalline silicon production waste is dust from gas cleaning systems of electric ore smelting furnaces. In this regard, this paper studies its chemical composition and the possibilities of using valuable components (amorphous silica, carbon nanotubes (CNT)) included in its composition. The study demonstrates that it is possible to separate this product by flotation into 3 components — sand fraction, flotation tailings enriched in SiO2, and froth enriched in carbon in the form of CNT. The structure of carbon nanotubes was studied and their physical and mechanical properties were determined: elastic modulus (2000 GPa), tensile strength (75 GPa), and thermal conductivity (4000 W/(m·K)). The amount of heat required to obtain 1 kg of CNT in electric ore smelting furnaces was calculated. Based on the material balance of commercial silicon electric smelting, it was found that 153 kg of CNT and 336 kg of flotation tailings are formed per ton of crystalline silicon during the endothermic process. Flotation tailings consist of 75 % amorphous microsilica particles. According to heat effect and Gibbs energy calculations made for amorphous microsilica formation reactions, it was found that all processes are exothermic, and the process of solid silicon carbide particles (2SiC + 3O2 → 2SiO2 + 2CO) oxidation with air oxygen has the highest thermodynamic probability. The economic efficiency of using amorphous silica to produce casting silumins was calculated, and its results clearly demonstrate a quick payback period (6 months), as well as a high level of its profitability (USD 819672).","PeriodicalId":14693,"journal":{"name":"Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91165704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-17DOI: 10.17073/1997-308x-2021-3-14-21
M. A. Marieva, A. Shatsov
Hysteresis alloys based on the Fe–Cr–Co system are of scientific and practical interest, primarily due to their high manufacturability, high level and temperature stability of magnetic properties, which provide the required hysteresis magnet performance including residual magnetic induction, coercive force, and loop squareness ratio. The research was aimed to control and stabilize the Fe–Cr–Co ridge alloy magnetic properties using reageing. The 22Kh15K4MS hard magnetic powder alloy was investigated after quenching and multistage aging. Billets were obtained by cold pressing at a pressure of 600 MPa and subsequent sintering in vacuum. The samples obtained by sintering in the α phase in the presence of the liquid phase formed during contact melting had a porosity of up to 1 %. The concentration heterogeneity of chromium and cobalt distribution was 0.06–0.08. The alloy magnetic structure parameters were determined by electron microscopy. The relationship between the magnetic structure formation kinetics during aging and the level of magnetic properties was established. After aging, the fine structure of the 22Kh15K4MS alloy was represented by elongated α1 phase sections in the α2 phase matrix. The average particle sizes of the α1 phase were »124 nm in length and »44 nm in width after the first stage of aging, and they remained the same after final aging. It was shown that it is possible to control magnetic properties by reaging without repeated quenching. A slight change in the size and morphology of magnetic phase particles was observed during aging. The influence of the number of reaging cycles on the stability of magnetic properties over time was determined.
{"title":"Control of hysteretic properties in powder alloys based on the Fe–Cr–Co system","authors":"M. A. Marieva, A. Shatsov","doi":"10.17073/1997-308x-2021-3-14-21","DOIUrl":"https://doi.org/10.17073/1997-308x-2021-3-14-21","url":null,"abstract":"Hysteresis alloys based on the Fe–Cr–Co system are of scientific and practical interest, primarily due to their high manufacturability, high level and temperature stability of magnetic properties, which provide the required hysteresis magnet performance including residual magnetic induction, coercive force, and loop squareness ratio. The research was aimed to control and stabilize the Fe–Cr–Co ridge alloy magnetic properties using reageing. The 22Kh15K4MS hard magnetic powder alloy was investigated after quenching and multistage aging. Billets were obtained by cold pressing at a pressure of 600 MPa and subsequent sintering in vacuum. The samples obtained by sintering in the α phase in the presence of the liquid phase formed during contact melting had a porosity of up to 1 %. The concentration heterogeneity of chromium and cobalt distribution was 0.06–0.08. The alloy magnetic structure parameters were determined by electron microscopy. The relationship between the magnetic structure formation kinetics during aging and the level of magnetic properties was established. After aging, the fine structure of the 22Kh15K4MS alloy was represented by elongated α1 phase sections in the α2 phase matrix. The average particle sizes of the α1 phase were »124 nm in length and »44 nm in width after the first stage of aging, and they remained the same after final aging. It was shown that it is possible to control magnetic properties by reaging without repeated quenching. A slight change in the size and morphology of magnetic phase particles was observed during aging. The influence of the number of reaging cycles on the stability of magnetic properties over time was determined.","PeriodicalId":14693,"journal":{"name":"Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya","volume":"300 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77036639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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