Pub Date : 2023-03-15DOI: 10.17073/1997-308x-2023-1-39-48
V. Gorshkov, P. Miloserdov, D. Kovalev, O. Boyarchenko
Materials based on molybdenum-aluminium-carbon compounds have a considerable potential for use under intense wear conditions at elevated temperatures. This paper presents the experimental results of self-propagating high-temperature synthesis of compounds within the Mo-Al-C system. By combining two processes: SHS of the elements and SHS-metallurgy, cast materials containing the Mo3Al2C, Mo2C, Mo3Al, and Mo3Al8 phases were obtained. The experiments used mixtures with compositions calculated according to the ratio (1 - α)(3MoO3-8Al-C)/α(3Mo-2Al-C), where a varied in the range from 0 to 1. The synthesis was carried out in a laboratory reactor of 3 L volume at an initial argon pressure of 5 MPa. The mass of the initial mixtures in all experiments was 20 g. The process of combustion was initiated by a 0.5 mm diameter molybdenum wire spiral by applying 28 V voltage to it. The resulting end products were studied by X-ray diffraction and local microstructural analysis. A significant influence of the ratio of the initial reagents on the synthesis parameters, phase composition, and microstructure of the target products was established. Introduction into the high-exothermic mixture 3MoO3-8Al-C inert “cold” mixture 3Mo-2Al-C leads to an increase in the content of carbide phases in the ingots. The possibility of obtaining cast materials based on the triple phase Mo3Al2C, the maximum content of which is 87 wt. % at the content of the “cold” mixture in the charge α = 0.4 is shown. The presence of secondary phases of molybdenum carbide (Mo2C) and molybdenum aluminides (Mo3Al8 , Mo3Al) in the final products is due to a change in the composition of the initial mixture caused by the ejection of components during combustion and insufficient existence time of the melt formed in the combustion wave.
{"title":"SHS of cast materials in the Mo-Al-C system","authors":"V. Gorshkov, P. Miloserdov, D. Kovalev, O. Boyarchenko","doi":"10.17073/1997-308x-2023-1-39-48","DOIUrl":"https://doi.org/10.17073/1997-308x-2023-1-39-48","url":null,"abstract":"Materials based on molybdenum-aluminium-carbon compounds have a considerable potential for use under intense wear conditions at elevated temperatures. This paper presents the experimental results of self-propagating high-temperature synthesis of compounds within the Mo-Al-C system. By combining two processes: SHS of the elements and SHS-metallurgy, cast materials containing the Mo3Al2C, Mo2C, Mo3Al, and Mo3Al8 phases were obtained. The experiments used mixtures with compositions calculated according to the ratio (1 - α)(3MoO3-8Al-C)/α(3Mo-2Al-C), where a varied in the range from 0 to 1. The synthesis was carried out in a laboratory reactor of 3 L volume at an initial argon pressure of 5 MPa. The mass of the initial mixtures in all experiments was 20 g. The process of combustion was initiated by a 0.5 mm diameter molybdenum wire spiral by applying 28 V voltage to it. The resulting end products were studied by X-ray diffraction and local microstructural analysis. A significant influence of the ratio of the initial reagents on the synthesis parameters, phase composition, and microstructure of the target products was established. Introduction into the high-exothermic mixture 3MoO3-8Al-C inert “cold” mixture 3Mo-2Al-C leads to an increase in the content of carbide phases in the ingots. The possibility of obtaining cast materials based on the triple phase Mo3Al2C, the maximum content of which is 87 wt. % at the content of the “cold” mixture in the charge α = 0.4 is shown. The presence of secondary phases of molybdenum carbide (Mo2C) and molybdenum aluminides (Mo3Al8 , Mo3Al) in the final products is due to a change in the composition of the initial mixture caused by the ejection of components during combustion and insufficient existence time of the melt formed in the combustion wave.","PeriodicalId":14561,"journal":{"name":"Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings. Powder Metallurgy аnd Functional Coatings)","volume":"80 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86525044","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 : 2023-03-15DOI: 10.17073/1997-308x-2023-1-49-62
S. V. Briakunov, A. Kurlov
A large specific surface area of WC nanopowder determines its high chemical activity and makes it very sensitive to various impurities, among which oxygen is most harmful and unavoidable. During heating, oxygen interacts with carbon of WC being removed in the form of CO/CO2, which finally leads to the appearance of embrittling η-phases in the hard alloy, abnormal growth of WC grains, and formation of a porous microstructure. To prevent heavy decarburization of WC during vacuum sintering of hard alloy from a nanocrystalline powder mixture WC-6wt.%Co, in this work we compared three methods: addition of extra carbon to compensate for carbon loss as a result of decarburization; addition of Al to bind impurity oxygen into Al2O3 before it interacts with carbon of WC; and addition of ZrC to compensate for carbon loss and bind impurity oxygen into ZrO2. Nanocrystalline powder mixtures based on WC-6 wt.%Co with and without additions of C, Al, and ZrC were prepared from microcrystalline powders of WC, Co, Al, ZrC, and carbon black by high-energy milling, then they were compacted in a cylindrical mold by uniaxial pressing at a pressure of ~460 MPa and sintered in graphite crucibles for 15 min at 1380 °C in vacuum of ~10-2 Pa. The heating rate to the temperature of sintering was 10 °C/min. The initial powders, powder mixtures prepared therefrom, and sintered hard alloys were certified using X-ray diffraction, chemical analysis, scanning electron microscopy, BET adsorption method, helium pycnometry, and Vickers method. The studies performed showed that the average particle size in all the prepared powder mixtures does not exceed 100 nm, and the content of impurity oxygen in them varies from 3.3 to 4.3 wt.% depending on the additives. It was established that only a part of oxygen contained in the powder mixtures is in the chemisorbed state and takes part in the decarburization of WC during vacuum sintering. The Al additive is completely oxidized during milling of the powder mixture and transforms into nanocrystalline Al2O3, which only aggravates carbon loss during sintering and results in the formation of a multiphase and relatively porous microstructure of the hard alloy. On the contrary, using carbon and ZrC additives we managed to prevent the decarburization of WC during sintering of the hard alloy and to form a less porous microstructure in it. It was shown that the presence of ZrO2 inclusions does not impede intensive growth of WC grains during sintering, but rather promotes it. Carbon deficit slightly suppresses intensive WC grain growth during sintering of hard alloy leading to the formation of η-phases and to an increase in the density and microhardness, but the presence of oxide inclusions Al2O3 and ZrO2 in the microstructure reduces the values of these properties.
{"title":"Microstructure and phase composition of hard alloys produced from nanocrystalline powder mixture WC-6wt.%Co with C, Al and ZrC additives","authors":"S. V. Briakunov, A. Kurlov","doi":"10.17073/1997-308x-2023-1-49-62","DOIUrl":"https://doi.org/10.17073/1997-308x-2023-1-49-62","url":null,"abstract":"A large specific surface area of WC nanopowder determines its high chemical activity and makes it very sensitive to various impurities, among which oxygen is most harmful and unavoidable. During heating, oxygen interacts with carbon of WC being removed in the form of CO/CO2, which finally leads to the appearance of embrittling η-phases in the hard alloy, abnormal growth of WC grains, and formation of a porous microstructure. To prevent heavy decarburization of WC during vacuum sintering of hard alloy from a nanocrystalline powder mixture WC-6wt.%Co, in this work we compared three methods: addition of extra carbon to compensate for carbon loss as a result of decarburization; addition of Al to bind impurity oxygen into Al2O3 before it interacts with carbon of WC; and addition of ZrC to compensate for carbon loss and bind impurity oxygen into ZrO2. Nanocrystalline powder mixtures based on WC-6 wt.%Co with and without additions of C, Al, and ZrC were prepared from microcrystalline powders of WC, Co, Al, ZrC, and carbon black by high-energy milling, then they were compacted in a cylindrical mold by uniaxial pressing at a pressure of ~460 MPa and sintered in graphite crucibles for 15 min at 1380 °C in vacuum of ~10-2 Pa. The heating rate to the temperature of sintering was 10 °C/min. The initial powders, powder mixtures prepared therefrom, and sintered hard alloys were certified using X-ray diffraction, chemical analysis, scanning electron microscopy, BET adsorption method, helium pycnometry, and Vickers method. The studies performed showed that the average particle size in all the prepared powder mixtures does not exceed 100 nm, and the content of impurity oxygen in them varies from 3.3 to 4.3 wt.% depending on the additives. It was established that only a part of oxygen contained in the powder mixtures is in the chemisorbed state and takes part in the decarburization of WC during vacuum sintering. The Al additive is completely oxidized during milling of the powder mixture and transforms into nanocrystalline Al2O3, which only aggravates carbon loss during sintering and results in the formation of a multiphase and relatively porous microstructure of the hard alloy. On the contrary, using carbon and ZrC additives we managed to prevent the decarburization of WC during sintering of the hard alloy and to form a less porous microstructure in it. It was shown that the presence of ZrO2 inclusions does not impede intensive growth of WC grains during sintering, but rather promotes it. Carbon deficit slightly suppresses intensive WC grain growth during sintering of hard alloy leading to the formation of η-phases and to an increase in the density and microhardness, but the presence of oxide inclusions Al2O3 and ZrO2 in the microstructure reduces the values of these properties.","PeriodicalId":14561,"journal":{"name":"Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings. Powder Metallurgy аnd Functional Coatings)","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87308641","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 : 2023-03-15DOI: 10.17073/1997-308x-2023-1-75-84
M. Dvornik, N. Vlasova
In this paper, comparative studies of the microstructure, mechanical characteristics and service life of a cutting insert made of submicron cemented carbide WC-10Co, obtained as a result of recycling VK10 cemented carbide by Electro Discharge Erosion (EDE) in oil, were carried out. The specific energy consumption directly for the formation of pulses in the process of EDE is to a relatively small value (5.7 kW·h/kg). Excess carbon formed as a result of oil pyrolysis during EDE was removed by heat treatment. The granulometric composition of the obtained powder and the microstructure of the particles were studied. It is shown that the particles of the resulting powder consist of plate-like WC grains with an average diameter of 0.46 pm and interlayers of cobalt. The WC-10Co cutting insert, obtained by sintering this powder in vacuum, was used for a comparative analysis of service life during fine turning of aluminum alloy D16T. As objects for comparative analysis, cutters equipped with blades made of industrial alloys VK8 and VK6OM of a similar design were used. The microstructure and mechanical characteristics of the experimental alloy and the analogues presented have been studied. On the basis of studies of the microstructure and chemical composition of the back surface of the cutting inserts, the wear mechanism of the cutters was analyzed. It is shown that the hardness of the alloys has the main effect on their wear resistance when cutting an aluminum alloy with the presented cutters. The influence of the hardness of the cutters on the surface roughness of the resulting part was also studied. The obtained submicron cemented carbide WC-10Co exhibits the highest hardness (1590 HV) and wear resistance of the presented samples due to the smallest WC grain diameter (0.59 pm).
{"title":"Comparative analysis of the tool life of submicron hard alloy WC-10Co sintered from powder obtained by electro discharge in oil","authors":"M. Dvornik, N. Vlasova","doi":"10.17073/1997-308x-2023-1-75-84","DOIUrl":"https://doi.org/10.17073/1997-308x-2023-1-75-84","url":null,"abstract":"In this paper, comparative studies of the microstructure, mechanical characteristics and service life of a cutting insert made of submicron cemented carbide WC-10Co, obtained as a result of recycling VK10 cemented carbide by Electro Discharge Erosion (EDE) in oil, were carried out. The specific energy consumption directly for the formation of pulses in the process of EDE is to a relatively small value (5.7 kW·h/kg). Excess carbon formed as a result of oil pyrolysis during EDE was removed by heat treatment. The granulometric composition of the obtained powder and the microstructure of the particles were studied. It is shown that the particles of the resulting powder consist of plate-like WC grains with an average diameter of 0.46 pm and interlayers of cobalt. The WC-10Co cutting insert, obtained by sintering this powder in vacuum, was used for a comparative analysis of service life during fine turning of aluminum alloy D16T. As objects for comparative analysis, cutters equipped with blades made of industrial alloys VK8 and VK6OM of a similar design were used. The microstructure and mechanical characteristics of the experimental alloy and the analogues presented have been studied. On the basis of studies of the microstructure and chemical composition of the back surface of the cutting inserts, the wear mechanism of the cutters was analyzed. It is shown that the hardness of the alloys has the main effect on their wear resistance when cutting an aluminum alloy with the presented cutters. The influence of the hardness of the cutters on the surface roughness of the resulting part was also studied. The obtained submicron cemented carbide WC-10Co exhibits the highest hardness (1590 HV) and wear resistance of the presented samples due to the smallest WC grain diameter (0.59 pm).","PeriodicalId":14561,"journal":{"name":"Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings. Powder Metallurgy аnd Functional Coatings)","volume":"80 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73955468","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 : 2023-03-15DOI: 10.17073/1997-308x-2023-1-63-74
A. Chernogor, I. V. Blinkov, D. S. Belov, V. S. Sergevnin, A. P. Demirov
The influence of nickel on the structure and properties of Ti-Cr-N ion-plasma coatings obtained by arc-PVD method has been studied. With a nickel content of up to 11.9 at. %, the coating consists of Cr2N, Ti1 – xCrxN, and metallic Ni. Upon further increase in Ni concentration in the coating, intermetallic compound Ni3Ti is formed. The structure of the coatings was studied using the transmission electron microscopy. The coatings of Ti-Cr-N system are characterized by a columnar structure, in the columns of which Ti1 - xCrxN and Ti1 - yCryN (x > y) sublayers, being several nanometers thick and containing variable concentration of titanium and chromium, as well as Cr2N sublayers of about 25 nm are formed due to the complete solubility of TiN and Cr2N and the planetary rotation of the substrates, resulting in layer-by-layer stacking of the components of the evaporated cathodes. This structure remains intact in coatings of Ti-Cr-N-Ni system with a low nickel concentration (on the order of tenths of at. %). However, upon that, the column size refinement and an increase in biaxial compressive stresses from 6.7 to 9.7 GPa are observed, which results in an increase in hardness from 30 to 42 GPa. The coatings with a high nickel content are characterized by a multilayer architecture with an equiaxed polycrystalline structure of nanograins in layers. As Ni concentration increases, the hardness of the coating decreases to 16.7 GPa, which is associated with an increase in the fraction of relatively soft nickel in the coating and a decrease in macrostresses to -0.6 GPa. Upon that, the wear intensity increases from 3·10-15 to 5·10-15 m3/(N·m). The studied coatings of Ti–Cr–N and Ti–Cr–N–Ni systems are resistant to adhesive and cohesive destruction. With an increase in the nickel content upon measuring scratching, the destruction of the coatings occurs exclusively due to the plastic deformation.
{"title":"The influence of Ni on the composition, structure and properties of Ti-Cr-N coatings","authors":"A. Chernogor, I. V. Blinkov, D. S. Belov, V. S. Sergevnin, A. P. Demirov","doi":"10.17073/1997-308x-2023-1-63-74","DOIUrl":"https://doi.org/10.17073/1997-308x-2023-1-63-74","url":null,"abstract":"The influence of nickel on the structure and properties of Ti-Cr-N ion-plasma coatings obtained by arc-PVD method has been studied. With a nickel content of up to 11.9 at. %, the coating consists of Cr2N, Ti1 – xCrxN, and metallic Ni. Upon further increase in Ni concentration in the coating, intermetallic compound Ni3Ti is formed. The structure of the coatings was studied using the transmission electron microscopy. The coatings of Ti-Cr-N system are characterized by a columnar structure, in the columns of which Ti1 - xCrxN and Ti1 - yCryN (x > y) sublayers, being several nanometers thick and containing variable concentration of titanium and chromium, as well as Cr2N sublayers of about 25 nm are formed due to the complete solubility of TiN and Cr2N and the planetary rotation of the substrates, resulting in layer-by-layer stacking of the components of the evaporated cathodes. This structure remains intact in coatings of Ti-Cr-N-Ni system with a low nickel concentration (on the order of tenths of at. %). However, upon that, the column size refinement and an increase in biaxial compressive stresses from 6.7 to 9.7 GPa are observed, which results in an increase in hardness from 30 to 42 GPa. The coatings with a high nickel content are characterized by a multilayer architecture with an equiaxed polycrystalline structure of nanograins in layers. As Ni concentration increases, the hardness of the coating decreases to 16.7 GPa, which is associated with an increase in the fraction of relatively soft nickel in the coating and a decrease in macrostresses to -0.6 GPa. Upon that, the wear intensity increases from 3·10-15 to 5·10-15 m3/(N·m). The studied coatings of Ti–Cr–N and Ti–Cr–N–Ni systems are resistant to adhesive and cohesive destruction. With an increase in the nickel content upon measuring scratching, the destruction of the coatings occurs exclusively due to the plastic deformation.","PeriodicalId":14561,"journal":{"name":"Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings. Powder Metallurgy аnd Functional Coatings)","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91212052","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 : 2023-03-14DOI: 10.17073/1997-308x-2023-1-21-27
P. A. Lazarev, M. L. Busurina, A. Gryadunov, A. Sytschev, A. F. Belikova
A metal-carbide-intermetallic material based on combustion products of the layer system (Ti-Al-Si)/(Ti-C)/Ti was for the first time obtained with the help of self-propagating high-temperature synthesis (SHS) combined with pressing. Exothermic synthesis from elementary powders was carried out at a pressure of 10 MPa, and pressing of the hot synthesis product was carried out at a pressure of 100 MPa. It has been shown that SHS pressing contributes to the formation of permanent joints of «metal/carbide/intermetallic» layers. The main features of microstructure formation, phase composition, and strength properties of transition zones at the boundary between reacting SHS compositions, Ti-C and Ti-Al-Si and Ti-metal substrate are investigated. It is shown that during SHS reaction, a homogeneous microstructure of Ti-C and Ti-Al-Si layers with an insignificant content of cracks and pores is formed. The thickness of the transition zone between the layers was at least 15 µm. The main phase formed in the combustion product of Ti-Al-Si layer is, according to the results of X-ray phase analysis, triple phase Ti20Al3Si9, the content of which, calculated by the Rietveld method, was at least 87 wt. %. In addition, the combustion product contains a secondary phase of Ti3Al in the amount of 13 wt. %. The energy dispersion analysis revealed that diffusion of aluminium through the titanium carbide layer into the titanium substrate to a depth of approx. 30 µm is observed. Microhardness value of the combustion product of Ti-Al-Si layer was about 10 GPa. The rectilinear nature of crack propagation in the synthesized combustion product of Ti-Al-Si layer, as well as the Palmquist crack resistance coefficient varying within 5.1-5.7 MPa·m1/2, indicate the fragility of the material.
{"title":"Fabrication of (Ti-Al-Si)/(Ti-C)/Ti – layered alloy by SHS pressing","authors":"P. A. Lazarev, M. L. Busurina, A. Gryadunov, A. Sytschev, A. F. Belikova","doi":"10.17073/1997-308x-2023-1-21-27","DOIUrl":"https://doi.org/10.17073/1997-308x-2023-1-21-27","url":null,"abstract":"A metal-carbide-intermetallic material based on combustion products of the layer system (Ti-Al-Si)/(Ti-C)/Ti was for the first time obtained with the help of self-propagating high-temperature synthesis (SHS) combined with pressing. Exothermic synthesis from elementary powders was carried out at a pressure of 10 MPa, and pressing of the hot synthesis product was carried out at a pressure of 100 MPa. It has been shown that SHS pressing contributes to the formation of permanent joints of «metal/carbide/intermetallic» layers. The main features of microstructure formation, phase composition, and strength properties of transition zones at the boundary between reacting SHS compositions, Ti-C and Ti-Al-Si and Ti-metal substrate are investigated. It is shown that during SHS reaction, a homogeneous microstructure of Ti-C and Ti-Al-Si layers with an insignificant content of cracks and pores is formed. The thickness of the transition zone between the layers was at least 15 µm. The main phase formed in the combustion product of Ti-Al-Si layer is, according to the results of X-ray phase analysis, triple phase Ti20Al3Si9, the content of which, calculated by the Rietveld method, was at least 87 wt. %. In addition, the combustion product contains a secondary phase of Ti3Al in the amount of 13 wt. %. The energy dispersion analysis revealed that diffusion of aluminium through the titanium carbide layer into the titanium substrate to a depth of approx. 30 µm is observed. Microhardness value of the combustion product of Ti-Al-Si layer was about 10 GPa. The rectilinear nature of crack propagation in the synthesized combustion product of Ti-Al-Si layer, as well as the Palmquist crack resistance coefficient varying within 5.1-5.7 MPa·m1/2, indicate the fragility of the material.","PeriodicalId":14561,"journal":{"name":"Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings. Powder Metallurgy аnd Functional Coatings)","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74412407","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 : 2023-03-14DOI: 10.17073/1997-308x-2023-1-5-11
I. M. Mal'tsev, Yu. A. Getmanovsky
Antifriction tape sealing materials (TSM) are used in the manufacture of turbines. This work studied the mechanism of the increase in thickness of rolled products. The study showed that internal oxides of powder particles, which are reduced during sintering and annealing in hydrogen, cause a change in the size of tapes and compacts from NPG-80 and Nibon-20 clad powders. The distinctive feature of powders used in the work is the presence of a nickel shell around the particle of the solid lubricant (graphite or boron nitride). It was shown that an increase in sintering temperature and heating time to isothermal holding intensifies the growth of the tapes and samples The studies carried out point to a relationship between reduction processes occurring in hydrogen during heating, sintering, and annealing of NPG-80 and Nibon-20 powders with an increase in the thickness of the tape containing the solid lubricant in its composition. An increase in the duration of heating to isothermal holding at 1150 °C is accompanied by an increase in the thickness of rolled stock. Sintering of TSM Nibon-20 in the first mode (4 h to 1150 °C) gives an increase in thickness by 5-7 %, whereas sintering in the second mode (9 h to 1150 °C) gives an increase of 12-13 %. For NPG-80, the increase in thickness is 3-7 % and 8-11 %, respectively. This leads to some decrease in the physical and mechanical properties of TSM. Lower temperatures and higher heating rates are recommended for the sintering of sheet materials from NPG-80 and Nibon-20 in the hydrogen atmosphere. The increase in thickness of TSM from clad powders NPG-80 and Nibon-20 can be avoided if the sintering (heating) is carried out under pressure. By the method of electric rolling and subsequent hot rolling TSM is obtained from Nibon-20.
{"title":"Obtaining and properties of rolled products from clad powders NPG-80 and Nibon-20","authors":"I. M. Mal'tsev, Yu. A. Getmanovsky","doi":"10.17073/1997-308x-2023-1-5-11","DOIUrl":"https://doi.org/10.17073/1997-308x-2023-1-5-11","url":null,"abstract":"Antifriction tape sealing materials (TSM) are used in the manufacture of turbines. This work studied the mechanism of the increase in thickness of rolled products. The study showed that internal oxides of powder particles, which are reduced during sintering and annealing in hydrogen, cause a change in the size of tapes and compacts from NPG-80 and Nibon-20 clad powders. The distinctive feature of powders used in the work is the presence of a nickel shell around the particle of the solid lubricant (graphite or boron nitride). It was shown that an increase in sintering temperature and heating time to isothermal holding intensifies the growth of the tapes and samples The studies carried out point to a relationship between reduction processes occurring in hydrogen during heating, sintering, and annealing of NPG-80 and Nibon-20 powders with an increase in the thickness of the tape containing the solid lubricant in its composition. An increase in the duration of heating to isothermal holding at 1150 °C is accompanied by an increase in the thickness of rolled stock. Sintering of TSM Nibon-20 in the first mode (4 h to 1150 °C) gives an increase in thickness by 5-7 %, whereas sintering in the second mode (9 h to 1150 °C) gives an increase of 12-13 %. For NPG-80, the increase in thickness is 3-7 % and 8-11 %, respectively. This leads to some decrease in the physical and mechanical properties of TSM. Lower temperatures and higher heating rates are recommended for the sintering of sheet materials from NPG-80 and Nibon-20 in the hydrogen atmosphere. The increase in thickness of TSM from clad powders NPG-80 and Nibon-20 can be avoided if the sintering (heating) is carried out under pressure. By the method of electric rolling and subsequent hot rolling TSM is obtained from Nibon-20.","PeriodicalId":14561,"journal":{"name":"Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings. Powder Metallurgy аnd Functional Coatings)","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89363012","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 : 2023-03-14DOI: 10.17073/1997-308x-2023-1-12-20
M. A. Marieva, A. Shatsov
Hysteresis alloys based on Fe-Cr-Co system are extensively used in the instrument-making industry as a material for synchronous motors of navigation systems, in the electronic industry, and other mechanical engineering fields. The following requirements are imposed on Fe-Cr-Co alloys: temperature stability of magnetic characteristics over time, manufacturability, low porosity and concentration inhomogeneity, which allow to obtain high-quality magnetic and mechanical properties. Materials based on conventional alloying systems, such as Fe-Cr-Co, have outlived themselves. An urgent line of the development of new materials and improvement of the properties of existing ones is alloying with rare-earth metals. The effect produced by Sm addition on powder analogs of Fe-Cr-Co system remains unstudied. In this paper, 22Kh15K4MS powder magnetic hard alloy alloyed with samarium in an amount of 0.5 wt. % was studied. The billets were obtained by cold pressing at a pressure of 600 MPa followed by vacuum sintering. The concentration inhomogeneity of Cr, Co, Mo, Sm was determined after 12 different sintering modes. A model of diffusion homogenization of ridge alloys, which allows to numerically evaluate the effect of sintering modes on the concentration inhomogeneity, was plotted. The distributions of chromium, cobalt, and molybdenum correspond to the asymptotically logarithmically normal law. Samarium is unevenly distributed in the structure. The effect of samarium additions on the magnetic properties of the alloy has been demonstrated. The alloying of 22Kh15K4MS alloy with 0.5 wt. % of samarium allows to obtain powder hysteresis magnets with a coercive force in the range from 3.9 to 33.0 kA/m and a residual magnetic induction from 0.44 to 0.95 T.
{"title":"Prediction of the concentration inhomogeneity of powder magnetic hard alloys based on the Fe-Cr-Co-Mo system and the effect of Sm additions on their magnetic properties","authors":"M. A. Marieva, A. Shatsov","doi":"10.17073/1997-308x-2023-1-12-20","DOIUrl":"https://doi.org/10.17073/1997-308x-2023-1-12-20","url":null,"abstract":"Hysteresis alloys based on Fe-Cr-Co system are extensively used in the instrument-making industry as a material for synchronous motors of navigation systems, in the electronic industry, and other mechanical engineering fields. The following requirements are imposed on Fe-Cr-Co alloys: temperature stability of magnetic characteristics over time, manufacturability, low porosity and concentration inhomogeneity, which allow to obtain high-quality magnetic and mechanical properties. Materials based on conventional alloying systems, such as Fe-Cr-Co, have outlived themselves. An urgent line of the development of new materials and improvement of the properties of existing ones is alloying with rare-earth metals. The effect produced by Sm addition on powder analogs of Fe-Cr-Co system remains unstudied. In this paper, 22Kh15K4MS powder magnetic hard alloy alloyed with samarium in an amount of 0.5 wt. % was studied. The billets were obtained by cold pressing at a pressure of 600 MPa followed by vacuum sintering. The concentration inhomogeneity of Cr, Co, Mo, Sm was determined after 12 different sintering modes. A model of diffusion homogenization of ridge alloys, which allows to numerically evaluate the effect of sintering modes on the concentration inhomogeneity, was plotted. The distributions of chromium, cobalt, and molybdenum correspond to the asymptotically logarithmically normal law. Samarium is unevenly distributed in the structure. The effect of samarium additions on the magnetic properties of the alloy has been demonstrated. The alloying of 22Kh15K4MS alloy with 0.5 wt. % of samarium allows to obtain powder hysteresis magnets with a coercive force in the range from 3.9 to 33.0 kA/m and a residual magnetic induction from 0.44 to 0.95 T.","PeriodicalId":14561,"journal":{"name":"Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings. Powder Metallurgy аnd Functional Coatings)","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78432844","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 : 2023-03-14DOI: 10.17073/1997-308x-2023-1-28-38
S. Vadchenko, Yu. S. Vergunova, A. Rogachev, I. Kovalev, N. I. Mukhina
The dependence of the ignition temperature, combustion rate and composition of the resulting products on the concentration of Ti + C in mixtures with powder of a high-entropy alloy (HEA) FeNiCoCrCu and the initial mixture of metals forming it (MIX) has been studied. HEA was obtained by mechanical activation (MA) of a mixture of metal powders in argon. At the melting temperature, the high-entropy FeNiCoCrCu alloy decomposes into several phases, but the basis of the HEA alloy, as well as the alloy obtained by melting and crystallizing MIX, is a 5-component phase with an average formula Cu1.2Fe1.4Ni1.4Co1.4Cr. In addition, 5, 4, and 3-component phases with averaged formulas Cu2Ni2Co2Fe2Cr, Cu3Ni3Co2.9Fe2.5Cr, Cu4.8Ni4.5Co4.6Fe4.2Cr, Cu40Fe2Ni4Co2C, Cr12.5Fe3.2Co2.6Ni and Co3.2 Fe3,5 Cr are present in small amounts in the binder. Experiments on the ignition and combustion of mixtures of MIX and HEA with Ti + C were carried out in argon at atmospheric pressure. The combustion rate, ignition temperature, and maximum temperature reached in the thermal explosion of MIX and HEA mixtures with Ti + C increase with increasing Ti + C concentration. Due to the low exothermicity of the mixtures, the experiments were carried out at an initial temperature of 500 °С. At this initial temperature, the combustion limit of the samples occurs when the Ti + C concentration in the HEA and MIX mixtures is less than 30 %. Based on the results of scanning electron microscopy, the volume concentration of the number of titanium carbide (TiC) particles in molten samples was calculated. In an alloy with a HEA binder, the number of TiC particles per unit volume is 1.5-3.0 times greater than in an alloy with a MIX binder, and their size is correspondingly smaller. With an increase in the concentration of Ti + C from 30 to 40 % in a mixture with HEA, the number of TiC particles per unit volume decreases. In a mixture with MIX, the number of TiC particles per unit volume passes through a minimum. This is due to two opposite processes: on the one hand, the probability of the generation of TiC particles increases, on the other hand, their coagulation occurs.
{"title":"Formation of products upon ignition, combustion and melting of mixtures of high-entropy alloy FeNiCoCrCu with titanium and carbon","authors":"S. Vadchenko, Yu. S. Vergunova, A. Rogachev, I. Kovalev, N. I. Mukhina","doi":"10.17073/1997-308x-2023-1-28-38","DOIUrl":"https://doi.org/10.17073/1997-308x-2023-1-28-38","url":null,"abstract":"The dependence of the ignition temperature, combustion rate and composition of the resulting products on the concentration of Ti + C in mixtures with powder of a high-entropy alloy (HEA) FeNiCoCrCu and the initial mixture of metals forming it (MIX) has been studied. HEA was obtained by mechanical activation (MA) of a mixture of metal powders in argon. At the melting temperature, the high-entropy FeNiCoCrCu alloy decomposes into several phases, but the basis of the HEA alloy, as well as the alloy obtained by melting and crystallizing MIX, is a 5-component phase with an average formula Cu1.2Fe1.4Ni1.4Co1.4Cr. In addition, 5, 4, and 3-component phases with averaged formulas Cu2Ni2Co2Fe2Cr, Cu3Ni3Co2.9Fe2.5Cr, Cu4.8Ni4.5Co4.6Fe4.2Cr, Cu40Fe2Ni4Co2C, Cr12.5Fe3.2Co2.6Ni and Co3.2 Fe3,5 Cr are present in small amounts in the binder. Experiments on the ignition and combustion of mixtures of MIX and HEA with Ti + C were carried out in argon at atmospheric pressure. The combustion rate, ignition temperature, and maximum temperature reached in the thermal explosion of MIX and HEA mixtures with Ti + C increase with increasing Ti + C concentration. Due to the low exothermicity of the mixtures, the experiments were carried out at an initial temperature of 500 °С. At this initial temperature, the combustion limit of the samples occurs when the Ti + C concentration in the HEA and MIX mixtures is less than 30 %. Based on the results of scanning electron microscopy, the volume concentration of the number of titanium carbide (TiC) particles in molten samples was calculated. In an alloy with a HEA binder, the number of TiC particles per unit volume is 1.5-3.0 times greater than in an alloy with a MIX binder, and their size is correspondingly smaller. With an increase in the concentration of Ti + C from 30 to 40 % in a mixture with HEA, the number of TiC particles per unit volume decreases. In a mixture with MIX, the number of TiC particles per unit volume passes through a minimum. This is due to two opposite processes: on the one hand, the probability of the generation of TiC particles increases, on the other hand, their coagulation occurs.","PeriodicalId":14561,"journal":{"name":"Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings. Powder Metallurgy аnd Functional Coatings)","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86955495","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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