Metaloznavstvo ta obrobka metaliv最新文献

{"title":"Prediction of the mechanical properties of gray cast iron (probabilistic approach)","authors":"К.A. Sirenko, V.L. Mazur","doi":"10.15407/mom2023.03.019","DOIUrl":"https://doi.org/10.15407/mom2023.03.019","url":null,"abstract":"The article analyses the literature on the dependence of mechanical properties (tensile strength, hardness, etc.) of grey cast iron castings on the percentage of chemical elements in its composition and on the carbon equivalent, degree of eutecticity, and the ratio of carbon to silicon content. On the example of assessing the mechanical properties of cast iron with lamellar graphite, these dependencies are considered in the probabilistic aspect. It is emphasised that even within the same ranges of percentage of chemical elements in cast iron, as defined in standards or specifications, the values of its carbon equivalent, eutecticity, and the ratio of carbon to silicon content may be different. On the other hand, with different percentage ratios of chemical elements in the cast iron composition, the values of its carbon equivalent may be the same. It is shown that the conclusion about the presence or absence of correlation, in particular, between the hardness of castings and the carbon equivalent of the grey cast iron from which they are made, depends on the interval of variation of this argument. If the variation in the hardness of castings is significant and the interval for changing its carbon equivalent, calculated according to the chemical composition of cast iron specified in the standard for a particular casting product, is relatively short, the dependence of cast iron hardness on its carbon equivalent may not be evident. The disadvantage of the known empirical formulas intended for the approximate calculation of the tensile strength and hardness of cast iron based on its carbon element and eutecticity is the uncertainty of the choice of these indicators. It is proposed to use in such formulas the mathematical expectations (average values) of the carbon equivalent, eutecticity degree and the ratio of carbon to silicon content determined in the probabilistic approach using the Monte Carlo method. It is recommended that the distributions of chemical elements in grey cast iron within their intervals provided for in the standards be considered in accordance with the normal Gaussian law. Based on the information on the chemical composition and properties of grey cast iron with lamellar graphite smelted in accordance with the requirements of DSTU 8833-2019, the dependence of the carbon equivalent and the degree of eutecticity on the ratio of carbon to silicon content, as well as the strength and hardness of castings on these characteristics of the chemical composition of cast iron, have been identified. The formulas for determining the mechanical properties of grey cast iron with lamellar graphite have been calculated. Keywords: cast iron, casting, chemical composition, carbon equivalent, carbon to silicon ratio, degree of eutecticity, hardness, strength.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135083060","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}

{"title":"Trends in the global market of iron and iron castings in the first quarter of the 21st century","authors":"V.A. Gnatush, V.S. Doroshenko","doi":"10.15407/mom2023.03.030","DOIUrl":"https://doi.org/10.15407/mom2023.03.030","url":null,"abstract":"The analysis of the world market of iron and iron castings in 2002-2022 is presented. During the period from 2002 to 2022, the production of iron in the world grew at an average annual rate from 5.7 to 1.3%. An increase in the domestic consumption of iron by the producing countries was noted. The main consumers of cast iron are steel and cast iron production. The volumes of production, export, import, and consumption of cast iron compared to world GDP in 2002, 2012, and 2022 are shown. The top ten producers of cast iron in 2018 and 2022 are presented. Ukraine occupies the 12th position. A comparison of the dynamics of the production of iron and cast iron shows that during 2002-2021, the average annual growth rate of production of cast iron in the world was 4.0%, and that of cast iron was 2.0%. The ratings of the world manufacturers of iron castings in 2018 and 2021 were considered. The production of iron castings in the world is characterized by both increasing (2002-2011) and stable production (2012-2021). Today, cast iron remains the most widely used casting material. The main reasons for the long-lasting dominance of cast iron in a wide range of products are related to its mechanical and physical properties and its competitive price. If all ferrous alloys in the global foundry production make up more than 80%, then we are living in the Iron Age. The review provides two examples from the \"cast iron world\" that describe the development of centrifugal casting of high-strength cast iron pillars with lengths from 9 to 30 m and with a casting cycle time of up to 12 minutes for a base pillar. Such utility poles weigh less than wooden poles and are much lighter than concrete poles, have high fire resistance, withstand significant wind loads and have a service life of more than 75 years, surpassing both steel and wood. It was also noted that cast iron is actively used for the production of household utensils, with a projected increase in its output. Keywords: market, cast iron, cast iron castings, trends, production.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":"219 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135083056","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}

{"title":"Complex chromium alitization of carbon steels in chlorine environment","authors":"T.V. Loskutova, Y.A. Kononenko","doi":"10.15407/mom2023.03.011","DOIUrl":"https://doi.org/10.15407/mom2023.03.011","url":null,"abstract":"The authors investigated the influence of the nature of the chlorine-containing activator on the structure, chemical composition, and some properties of diffusion layers formed during complex chromium-alloying of carbon steels in a chlorine environment. On the basis of thermodynamic calculations, the quantitative ratio of saturating elements (chromium and aluminum) and rational coating temperatures were determined. It was determined that for the complex chromoalitization of steels, an increased amount of chromium in the composition of the saturating mixture is necessary. Based on the data obtained, the temperature intervals for complex chromoalitization of carbon steels in a chlorine environment were recommended to be 800-1100°C. Coatings were applied at a temperature of 950-1050°C for 2 hours in a saturating mixture of the following composition: 45 % wt. chromium, 5 % wt. aluminum, 47 % wt. Al2O3 and 3.0 % by weight of the activator. The chlorine-containing compounds NH4Cl and NiCl2 were used as activators. The structure, chemical composition, and distribution of microhardness along the cross-section of the obtained chrome-aluminum coatings were investigated. It was found that the distribution of structural components in both types of coatings obtained at a temperature of 950 °C is almost identical. At the same time, the structure of the diffusion zone obtained by using NiCl2 as an activator shows the presence of a two-phase layer of dark inclusions, the main component of which is small columnar crystals. The thickness of the obtained coatings is 23-32 microns. An increase in the saturation temperature to 1050°C during complex chromoalitization using NH4Cl as an activator leads to an increase in the thickness of the resulting coatings to 200-220 microns, with the amount of aluminum on the surface being 16.59% by weight and chromium 4.36% by weight. Keywords: chromium, aluminum, carbon steel, activator, diffusion coatings.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":"2014 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135083061","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}

{"title":"Determination of the dispersion hardening ability of a new die steel with controlled austenitic transformation","authors":"V.Ya. Grabovskiy, O.V. Lysytsia","doi":"10.15407/mom2023.03.003","DOIUrl":"https://doi.org/10.15407/mom2023.03.003","url":null,"abstract":"The chemical composition of the stamping steel for high operating temperatures (above 700 °C) with controlled austenitic transformation during operation (CATO) was adjusted to implement its hardening by the dispersion hardening (aging) mechanism. The base steel was chosen as 3Х3Н8М7Ф, in which quenching and subsequent aging did not lead to such hardening. It was taken into account that in order to implement dispersion hardening, CATO steels should have a predominantly austenitic (rather than martensitic) structure in the hardened state, which was not provided for the base steel. As a result of changes in the content of Mn, Ni and C in the base steel, it was determined that the required conditions are met by CATO steel of grade 4Х3Н3Г6М7Ф (95 % austenite after quenching with a predominantly ferrite base in the annealed state). The experiments have established the ability of this steel to harden with ageing. Strength growth was determined by high-temperature tensile tests immediately after aging (without intermediate cooling of samples to room temperature), which is a feature of testing steels with CATO. The highest strength growth (compared to the quenched state) is provided by heat treatment in the following mode: quenching 1150 °C, 2 hours, oil and subsequent aging 725 °C, 2 hours (at a test temperature of 750 °C, s0,2 increases to 674 MPa, sВ to 697 MPa). This hardening is due to the release of dispersed particles of the Laves phase of Fe2Mo and carbide of type VC during aging. In the aged state, the steel retains its austenitic structure at high temperatures, and when cooled below 200 °C, it undergoes a γ → α transformation according to martensitic kinetics and acquires a hardness of 49 HRC. The achieved high-temperature (700...900 °C) strength characteristics of 4Х3Н3Г6М7Ф steel are twice as high as those of the high-temperature die steel 5Х3В3МФС (DI23) and are not inferior to the heat-resistant alloy ХН35ВТЮ (EI787). This makes it possible to effectively use it instead of commercially available heat-resistant martensitic die steels at operating temperatures above 700 °C. Keywords: die steels CATO, alloying, quenching, austenitic structure, dispersion hardening, high-temperature strength.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135083057","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}

{"title":"Complex modification of AlSi9Cu3(Fe) alloy by using cobalt, vanadium and molybdenum","authors":"M. M. Voron, S. L. Polyvoda, O. O. Yasynska","doi":"10.15407/mom2023.03.041","DOIUrl":"https://doi.org/10.15407/mom2023.03.041","url":null,"abstract":"Aluminum casting alloys of the Al-Si and Al-Si-Cu systems are among the most widely used materials for machine building. Their wide use is associated with low cost, high manufacturability, excellent ability for multiple recycling and sufficient level of mechanical properties. Increasing of Al-Si-Cu alloys mechanical characteristics always remains as a relevant task, which is often solved by several components modification. Presented work is dedicated to investigation of Co, V and Mo complex influence on the structural phase state and mechanical properties of the widely used AlSi9Cu3(Fe) alloy. All modifying additives were added in the amount of 0.1-0.2 wt. %. At the same time, their total content did not exceed 0.5 wt. %. It is shown that the complex modification of AlSi9Cu3(Fe) with cobalt and vanadium contributes to a significant grain refinement and increasing strength of the alloy by more than 20% while maintaining plasticity. At the same time, cobalt mainly performs the function of a modifier of eutectic components, and vanadium plays the role of a grain refiner. Simultaneous modification of the alloy with vanadium and molybdenum ensures refining of all structural components and strength elevating. Both components perform the function of nucleation. The simultaneous addition of cobalt and molybdenum shows the effect of cobalt on eutectic components. Molybdenum actually does not have a nucleating effect and is mainly goes to iron-containing phases. As a result, average mechanical properties can be observed. Triple modification makes it possible to obtain maximum refining of all structural-phase components and increase the strength of the alloy. The highest microhardness of such alloys indicates potentially high level of mechanical properties at elevated temperatures. Keywords: cast aluminum alloys, modification, AlSi9Cu3(Fe), structure, phase composition, mechanical properties.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135083055","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}

{"title":"The structure of castings of cast composites of the Cu-V system obtained by electron beam casting","authors":"R. F. Likhatskyi, Ye. O. Matviets","doi":"10.15407/mom2023.03.056","DOIUrl":"https://doi.org/10.15407/mom2023.03.056","url":null,"abstract":"Keywords: Cu-V alloys, new electrotechnical materials, electron beam casting technology, as-cast composite materials, microstructure. Keywords: Cu-V alloys, new electrotechnical materials, electron beam casting technology, as-cast composite materials, microstructure.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135083064","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}

{"title":"Environmental aspects of foundry aluminum slag processing","authors":"V.V. Dovbenko","doi":"10.15407/mom2023.03.050","DOIUrl":"https://doi.org/10.15407/mom2023.03.050","url":null,"abstract":"Data on the influence of the aluminum slag processing process on the state of the atmospheric environment are presented. Calculations of the dispersion of pollutants (PO) in the surface layer of atmospheric air were carried out, which showed the absence of exceeding the maximum permissible concentrations (MPC) for carbon monoxide, nitrogen dioxin, sulfur dioxide, hydrogen chloride and dust. Analysis of emissions was carried out for extreme conditions of equipment operation. It was established that under such technological conditions, the maximum concentration of pollutants is: NO2 ≤ values of 0.2 MPC, and the rest of the pollutants do not exceed - 0.05 MPC. To identify the actual concentrations of hazardous substances at the border of the sanitary protection zone (SZZ), laboratory tests were performed at a distance of 300 m from the emission source. It was established that emissions of pollutants into the atmosphere from the industrial site on the territory of the enterprise and on the border of the calculated sanitary protection zone are less than the MPC of the atmospheric air of populated areas and will not have a significant harmful effect on the environment, provided that the sanitary and technological requirements for operation are met. The level of the content of harmful impurities in the air does not exceed the hygienic standards outside the sanitary protection zone, which are established for the atmospheric air of populated areas. Keywords: ecology, pollutants, maximum permissible concentration, aluminum slag.","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135083054","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}

{"title":"Features of structure formation in economy alloyed chromo-manganese iron-carbon alloys for metallurgical equipment parts","authors":"V. L. Pliuta, A. Nesterenko","doi":"10.15407/mom2023.02.015","DOIUrl":"https://doi.org/10.15407/mom2023.02.015","url":null,"abstract":"It was established that in cast chromium-manganese alloys of the transition class Fe–C–Mn–Cr system (carbon content no more than 2.2%) with a certain combination of Mn and Cr, the formation of crystals of highly hard carbide Me7C3 is possible. The relationship between the phase-concentration parameters and the structure formation of alloys of the Fe–C–Mn–Cr system was studied, the analysis of the relationship between the phase-concentration parameters, structure formation and properties was carried out on the compositions of the Fe–C–Mn and Fe–C– Mn–Cr with 1.5-2.1% C, with a variable content of Mn, Cr and additives of other alloying elements - Si and Ni at the level of impurities. A phase-concentration diagram of the crystallization of the alloys of this system was constructed, delimiting the regions of crystallization P → γ-Fe, P → γ-Fe + Me3C and P →(γ -Fe + Me7C3) + (γ-Fe + Me3C). It is shown that economically alloyed chromium-manganese alloys of the Fe–Mn–Cr–C system with eutectics based on Me7C3 carbide are characterized by a high level of shock-abrasive wear resistance, and the results of the conducted studies indicate the prospects of using economically alloyed chromium-manganese alloys and can be recommended for further research and use as wear-resistant materials for the manufacture of parts of replaceable metallurgical equipment, which are operated in severe conditions of abrasive and shock-abrasive wear. Keywords: phase-concentration diagram, microstructure, Me7C3 carbide, impact-abrasive wear resistance, chromium-manganese alloys","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46748697","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}

{"title":"Multi-component NiFeCrWMo high entropy alloy, resulted from mechanical alloying","authors":"S. Nakonechnyi, D.R. Dmytryshyn, V.О. Moroz, A. Yurkova","doi":"10.15407/mom2023.02.044","DOIUrl":"https://doi.org/10.15407/mom2023.02.044","url":null,"abstract":"In this work, the evolution of the structure and phase composition of the multicomponent Ni-Fe-Cr-W-Mo system during mechanical alloying (MA) of an equiatomic mixture of elemental metal powders in a planetary mill is investigated. The formation of the phase composition and structure of the powdered equiatomic high-entropy NiFeCrWMo alloy at different stages of mechanical alloying was determined by scanning electron microscopy, X-ray diffraction and X-ray spectral analysis. It was found that during 10 hours of МА, a single-phase high-entropy alloy with the structure of a BCC solid solution in the nanostructural state with a crystallite size of 22 nm and a lattice strain (microstress) of 0.61 % was formed. It was shown that the metal components were completely dissolved in the solid state during mechanical alloying, in contrast to their limited solubility under equilibrium conditions. Moreover, despite the different features of the formation of solid solutions in high-entropy alloys and traditional materials, the order of dissolution of element atoms in the lattice of a solid solution follows general principles and occurs depending on the melting point in the following sequence: Ni→Fe→Cr→Mo→W. The average particle size of the produced powdered NiFeCrWMo high-entropy alloy is 3.8 μm, and their shape is predominantly spherical or close to spherical. The microstructure of the particles of the powdered NiFeCrWMo high-entropy alloy at the early stage (1.5 hours) of mechanical alloying is a layered structure formed in the process of grinding, deformation, and cold welding of particles of elemental metal powders. After 10 hours of МА, the microstructure of the alloy particles becomes homogeneous and contains a small amount of WC inclusions as a result of milling due to wear of grinding bodies in the MА process. The obtained NiFeCrWMo high-entropy alloy can be used in the future as a component/binder for other composite materials, for example, hard alloys based on WC to replace Co. Keywords: high-entropy alloy, mechanical alloying, structure, phase composition, solid solution, nanostructure","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41963814","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}

{"title":"Evaluation of approaches to predicting the properties of synthetic cast iron in foundry production","authors":"К. Sirenko, V. Mazur","doi":"10.15407/mom2023.02.024","DOIUrl":"https://doi.org/10.15407/mom2023.02.024","url":null,"abstract":"An overview of approaches to assessing the dependence of the mechanical properties of products made of synthetic iron smelted in induction crucible furnaces on the content of carbon and the content of silicon in its chemical composition, as well as on the carbon equivalent, the degree of eutecticity, and the ratio of the carbon content to the silicon content is given. The statistical parameters of the percentage distributions of the specified elements in the chemical composition of cast irons with lamellar graphite produced in accordance with the requirements of DSTU 8833-2019 were analyzed. The values ​​of the carbon equivalent of the chemical state of these cast irons and the values ​​of their degree of eutecticity were calculated according to common formulas for determining these indicators using the Monte Carlo method and using a probabilistic approach taking into account the content of each element in the chemical composition of cast iron. It is emphasized that, from a probabilistic point of view, the values ​​of the carbon equivalent and the degree of eutecticity may not coincide in different batches of cast iron, even with the same values ​​of the percentage content of chemical elements in its composition. It is shown that with an increase in the carbon equivalent and the degree of eutecticity, the strength and hardness of cast iron produced in accordance with DSTU 8833-2019 decrease. As the carbon content and carbon equivalent increase, the ratio of carbon content to silicon content decreases. In industrial batches of cast iron brake pads and «Khanin wedge» manufactured in accordance with GOST 30249-97 and GOST 34503-2018, the hardness of these products does not depend on the carbon equivalent due to the small range of the carbon equivalent values. Keywords: foundry products, cast iron, chemical composition, carbon equivalent, ratio of carbon content to silicon content, degree of eutecticity, hardness, strength","PeriodicalId":33600,"journal":{"name":"Metaloznavstvo ta obrobka metaliv","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48163638","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}