113 results on '"HD9506-9624"'
Search Results
102. High-entropy AlCoFeCrVNi and AlCoFeCrVTi alloys obtained by mechanical alloying and subsequent sintering
- Author
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Cherniavskyi V. V., Yurkova Alexandra I., Kushnir V.V., and Stepanov O.V.
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Mining engineering. Metallurgy ,TN1-997 ,Mineral industries. Metal trade ,HD9506-9624 - Abstract
High-entropy AlCoFeCrVNi and AlCoFeCrVTi alloys were obtained by mechanical alloying and sintering, and it was shown that after mechanical alloying alloys consist mainly of BCC solid solutionі and insignificant amount of FCC solid solutionі, which are in a nanostructural state. After sintering in a vacuum the alloys consist of FCC solid solutions and precipitates of intermetallic and carbide phases. After sintering under high pressure alloys consist of FCC and BCC solid solutions and the FCC solid solution is a predominant phase in both alloys. Also sintering under high pressure allows keeping nanostructural state in AlCoFeCrVNi and AlCoFeCrVTi alloys and increased microhardness.
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- 2018
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103. On the state of harmonization of technical standards in the field of aluminum products with international and european standards
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Pleshakov E. I., Bohun L. I., and Shvachko S. G.
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Mining engineering. Metallurgy ,TN1-997 ,Mineral industries. Metal trade ,HD9506-9624 - Abstract
The changes that are introduced into the designation of aluminum grades, foundry and deformable aluminum alloys are analyzed in accordance with the Law of Ukraine "On Standardization", which reorientes the national standardization system to European and international standards. The structure and content of existing national standards, including those harmonized with international and European standards, harmonization of existing standards, terms of their validity, prospects for application and development are characterized.
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- 2018
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104. Particularity of formation the cast structure of multicomponent niobium alloys Nb – Ti – Al
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Kuznetsova T. L., Brodnikovsky М. P., Rokуtska О. A., and Krapivka N. O.
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Mining engineering. Metallurgy ,TN1-997 ,Mineral industries. Metal trade ,HD9506-9624 - Abstract
The features of formation the dendritic heterogeneous cast structure of perspective multicomponent niobium alloys, including highly entropic alloys, which are due to physicochemical i thermophysical characteristics of alloys, are investigated. The preconditionthe necessity and ways for active intervention in the crystallization process for obtaining homogeneous defectless castings are established.
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- 2018
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105. Crystallization and structure of steel ingots under conditions of endogenous vibration treatment
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Kondratyuk Stanislav Ye., Shcheglov V. M., and Veis Valentyn I.
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Mining engineering. Metallurgy ,TN1-997 ,Mineral industries. Metal trade ,HD9506-9624 - Abstract
The effect of endogenous vibration treatment on kinetic parameters and characteristics of structure of a solidifying melt was studied on 16,3 t ingot of steel grade Х18Н10Т. Significant improvement in the quality of the ingot, homogeneity and dispersion of its cast structure, change in the extent of the main structural zones along the height and cross section of the ingot, the distribution and the number of nonmetallic inclusions are shown. An increase in impact strength by 25 – 30 % in rolled steel made from the ingot metal, which was subjected to endogenous vibration treatment during crystallization of the melt, was established.
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- 2018
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106. Influence of periodic oscillations and fluctuations of the metal level in the crystallizer on the continuous casting process
- Author
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Smirnov Oleksiy М., Verzilov Aleksei P., and Kuberskiy S. V.
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Mining engineering. Metallurgy ,TN1-997 ,Mineral industries. Metal trade ,HD9506-9624 - Abstract
The reasons of occurrence of wave processes on a surface of a liquid metal at a continuous casting of slabs are analyzed. The influence of metal level fluctuations in the crystallizer on the occurrence of emergency situations and the quality of the billet is shown. Recommendations are proposed to reduce the probability of occurrence and development of wave processes.
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- 2018
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107. Structure and properties of Cr-, Zr-, Ti-electrospark coatings on iron
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Lobachova Galyna G. and Ivashchenko Ievgen V.
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electrospark doping ,physic-mechanical properties ,iron ,wear resistance of coatings ,penetration phases. ,Mining engineering. Metallurgy ,TN1-997 ,Mineral industries. Metal trade ,HD9506-9624 - Abstract
The effect of the intermediate layer of iron in electric-spark doping with transition metals (Zr, Ti, Cr) was investigated, which contributes to the formation of coatings enriched with penetration phases on the surface, which improves surface properties (microhardness up to 7.5 GPa and wear resistance 10.41 times).
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- 2019
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- View/download PDF
108. Inert gas absorption and pore formation in nickel-based hot-melt alloys
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O. S. Vodennikova, Yu. F. Ternovyi, and S. A. Vodennikov
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010302 applied physics ,Materials science ,Mining engineering. Metallurgy ,heat-resistant alloy ,Mineral industries. Metal trade ,Analytical chemistry ,TN1-997 ,02 engineering and technology ,Nickel based ,helium ,021001 nanoscience & nanotechnology ,01 natural sciences ,HD9506-9624 ,centrifugal spraying ,0103 physical sciences ,argon ,pore formation ,0210 nano-technology ,Hot melt ,Absorption (electromagnetic radiation) ,Inert gas ,gas spraying - Abstract
An integrated approach to the generalization and analysis of scientific and technical literature in the direction of improving the technological processes of spraying metal melts used a comprehensive approach The processing and analysis of experimental data for the determination of argon at different stages of heat-resistant alloy production were performed. Micro structural analysis of nickel-based heat-resistant alloys obtained by gas and centrifugal spraying was performed. A significant increase in the mass fraction of argon in the melt is shown when held in a furnace before gas or centrifugal spraying, the absence of capture of inert gas by sprayed liquid particles during centrifugal spraying is shown, unlike the process of gas spraying, it is shown. The results of the study indicate the absence of "dissolution" of Ar or a mixture of Ar-He in the liquid or solid state at argon levels up to 1 • 10-4% of the mass. It is established that centrifugal spraying of metal melts allows obtaining compact powders with small particle size distribution at relatively low energy consumption. It is also noted that argon is captured by the metal only in the process of moving on the disk, and not due to the weak dynamic gas interaction directly on the melt droplets. Hence, its amount in the metal increases after the argon’s injection into the furnace chamber and at the subsequent centrifugal spraying does not change, in comparison with gas spraying. A technological possibility has been found to significantly reduce the amount of gas pores and the mass fraction of inert gas in nickel-based heat-resistant alloys. Nickel-based heat-resistant alloys obtained by the method of gas and centrifugal spraying make it possible to improve the quality of products for the aviation industry, their reliability when operating in extreme conditions. Keywords: gas spraying, centrifugal spraying, heat-resistant alloy, argon, helium, pore formation.
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- 2021
109. Kinetics of the hydrogen reduction process of nickel oxide nanopowder in non-isothermal conditions
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Nust 'MISiS' and Tien Hiep Nguyen
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Materials science ,Hydrogen ,Kinetics ,chemistry.chemical_element ,nanopowder ,02 engineering and technology ,01 natural sciences ,Isothermal process ,HD9506-9624 ,hydrogen reduction ,activation energy ,Reduction (complexity) ,nickel ,0103 physical sciences ,010302 applied physics ,Mining engineering. Metallurgy ,Nickel oxide ,Mineral industries. Metal trade ,TN1-997 ,021001 nanoscience & nanotechnology ,non-isothermal conditions ,chemistry ,Chemical engineering ,kinetics ,Scientific method ,0210 nano-technology - Abstract
In this work the kinetics of the hydrogen reduction process of nickel oxide nanopowder in non-isothermal conditions were studied. NiO nanopowder was prepared in advance by thermal decomposition at 300°C of nickel hydroxide Ni(OH)2. Ni(OH)2 nanopowder was prepared by chemical deposition from aqueous solutions of nickel nitrate Ni(NO3)2 (10 wt. %) and alkali NaOH (10 wt. %) at room temperature, pH=9, under the condition of continuous stirring. The hydrogen reduction process of NiO nanopowder in non-isothermal conditions was carried out in the linear heating mode at a rate of 5°C/min in the temperature range 25–400°C. The study of the crystal structure and composition of the powder samples was performed by X-ray phase analysis. The specific surface area S of the powders was measured using BET method by low-temperature nitrogen adsorption. The average particle size D of powder samples was determined via the measured S value. The size and shape of the particles were investigated by scanning electron microscopic method. The calculation of kinetic parameters of the reduction process of nickel oxide in non-isothermal conditions was carried out by the differential-difference method using the data of thermogravimetric analysis and the equation for non-isothermal kinetics. It was revealed that the hydrogen reduction process of NiO nanopowder in non-isothermal conditions occurs in the temperature range 240–300°С with a maximum specific rate of 13,045•10-8 kg/s recorded at 280°С. The activation energy for the reduction process of NiO nanopowder was estimated at ~59 kJ/mol, which confirms the kinetic mode of limiting the process. It is shown that an increase in temperature to 280 °С can effectively increase the rate of the overall hydrogen reduction process of NiO nanopowder while guaranteeing the quality of the reduction product. The obtained Ni nanoparticles mainly have a rounded shape, their size ranges from 40–80 nm. Keywords: kinetics, nickel, nanopowder, hydrogen reduction, non-isothermal conditions, activation energy.
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- 2020
110. Increased stability die forged steel 4H4N5M4
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L. A. Myroniuk, D. V. Myroniuk, O. M. Sydorchuk, K. O. Gogaev, and O. K. Radchenko
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010302 applied physics ,Materials science ,business.product_category ,Mining engineering. Metallurgy ,heat treatment ,Metallurgy ,Mineral industries. Metal trade ,TN1-997 ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,HD9506-9624 ,forging ,0103 physical sciences ,Die (manufacturing) ,physical and mechanical properties ,steel ,structure ,0210 nano-technology ,business - Abstract
The results of researches on steel 4H4N5M4F2 modes thermo-deformation processing optimization are given. It is established that incomplete annealing (750 °С ± 20 °С in comparison with full annealing 860 °С) in cast and forged condition promotes to improve the machining of blanks for the manufacture of matrices. It is shown that the use of incomplete annealing, namely partial recrystallization promotes the formation of spheroidized rather than lamellar carbide phase, which leads to a decrease in the characteristics: strength threshold, yield strength, hardness 900 MPa, 800 MPa, 32 33 HRC in the cast state and 1200 MPa, 1050 MPa, 38 39 HRC in forged condition, respectively. This increases the fracture toughness: 180 J/cm2 in the cast state and 130 J/cm2 in the forged state. The optimized mode of forging at the temperature of 1170 ± 20 °С and heat treatment (hardening at 1100 ± 5 °С and tempering at 595 ± 5 °С) of steel 4H4N5M4F2 allowed to increase impact strength five times in comparison with cast experimental steel, and also to increase strength threshold of 100 MPa. Forged steel 4H4N5M4F2 has slightly lower heat resistance compared to cast, which hardens at temperatures above 630 °C during operation of the die steel tool. After operation of the extruder wheels made of investigated forged steel and forged steel 4H5MF1S, which was used at the enterprise in copper processing, the properties of both steels were determined. The investigated forged steel 4H4N5M4F2 is characterized by an increase in the strength threshold by 200 MPa and hardness by 6 HRC. After operation (production of 60 tons of copper products of M1 grade) the tool (wheel extruder) from H13 steel (analog 4H5MF1S) had micro and macrocracks on the side and inner parts, and in the investigated steel 4H4N5M4F2 such defects were absent. Thus, the studied steel is characterized by increased stability. Keywords: steel, heat treatment, forging, structure, physical and mechanical properties.
- Published
- 2020
111. Gold Mining in Northeast Antioquia: A Territorial Dispute over Development
- Author
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Bernal-Guzmán, Leidy-Jackelinne and Bernal-Guzmán, Leidy-Jackelinne
- Abstract
The objective of this article is to characterize the environmental conflict that takes place in the municipalities of Segovia and Remedios -located in Northeast Antioquia, Colombia- since there are simultaneously large-scale mining projects (promoted by the national government), and small-scale gold-mining operations (which have traditionally occurred). The convergence of these extractivist models has exacerbated social conflicts between local, private, institutional and illegal armed actors; it fosters violent processes of accumulation by dispossession, political persecution, and systematic violation of human rights; as well as problems associated with a deficit in health, education, social investment, and employment, which are enhanced in parallel with the deterioration of local ecosystems., Este artículo tiene como objetivo la caracterización del conflicto ambiental que tiene lugar en los municipios de Segovia y Remedios -pertenecientes al Nordeste antioqueño colombiano- pues allí se desarrollan, de forma paralela, proyectos mineros de gran escala (fomentada por el Gobierno Nacional) y explotaciones auríferas de pequeña escala (que se han dado de forma tradicional en la región). La convergencia de estas dos apuestas extractivas ha exacerbado conflictos sociales entre actores locales, privados, institucionales y armados ilegales, propiciando procesos violentos de acumulación por desposesión, persecución política, y violación sistemática de derechos humanos; así como problemáticas asociadas a un déficit en salud, educación, inversión social y empleo, que se agudizan paralelamente al deterioro de los ecosistemas locales.
- Published
- 2018
112. Knowledge Politics in Environmental Conflicts: A Case from Brazil
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Pereira, Aline R.B., Laube, Wolfram, Pereira, Aline R.B., and Laube, Wolfram
- Abstract
Following large environmental conflicts and disasters, economic endeavors -particular large-scale investments in mining or hydropower- are nowadays subjected to rigorous environmental law and regulations. The application of rules and regulations takes place in environmental administration and courts and includes environmental impact assessments (EIAs), licensing processes and litigation in court. Within these contexts, decision making is supposed to be based on rational reasoning and purportedly impartial scientific knowledge and information. Thus, citizens’ rights in resource conflicts and the effective enforcement of these rights in administrative, judicial, and political contestation become highly dependent on knowledge and information and the ways it is produced, interpreted, and valued in the interaction between people affected and investors, lays and experts, bureaucrats, legal practitioners and citizens. Political contestation becomes a seemingly technical dispute. This paper bases on a qualitative study of the conflicts surrounding the establishment of the large-scale iron-ore mining project Minas-Rio, in Conceição do Mato Dentro, Minas Gerais, Brazil, conducted in 2014-2015. It describes the problematic nature of the production of information and knowledge in a given political-economic context and the contestations surrounding the validity of apparently scientific results as they emerged alongside the environmental licensing process. Environmental studies and their technical evaluations are based on questionable assumptions and often lack accurate baseline data. The deficiency of public resources for independent investigation makes the environmental agencies dependent on services and information provided by mining companies. Apart from this form of collaboration, the prioritization of allegedly scientific “expert” knowledge, career trajectories of agencies’ personnel, and pressure by pro-mining politicians lead to the uncritical adoption of data, informatio, Tras grandes conflictos y desastres ambientales, los proyectos económicos, en particular las inversiones a gran escala en minería o energía hidroeléctrica, están hoy en día sujetos a leyes y reglamentos ambientales rigurosos. La aplicación de las normas y reglamentos tiene lugar en la administración pública y en los tribunales e incluye evaluaciones de impacto ambiental (EIAs), procesos de concesión de licencias y litigios en los tribunales. En este contexto, se supone que la toma de decisiones se basa en un razonamiento racional y en conocimientos e informaciones supuestamente científicas e imparciales. Así, los derechos de los ciudadanos en los conflictos ambientales y la aplicación efectiva de estos derechos en procesos de contestación administrativa, judicial y política dependen en gran medida del conocimiento, de la información y de las formas en que se producen, interpretan y valoran en la interacción entre las personas afectadas y los inversores, los expertos y no expertos, los burócratas, los profesionales del derecho y los ciudadanos. La discusión política se convierte en una disputa aparentemente técnica. El presente texto se basa en un estudio cualitativo de los conflictos en torno al establecimiento del proyecto minero a gran escala Minas-Río, en Conceição do Mato Dentro, Minas Gerais, Brasil, realizado en 2014-2015. Se describe la naturaleza problemática de la producción de información y conocimiento en un contexto político-económico dado y las disputas en torno a la validez de los resultados aparentemente científicos que surgieron en el proceso de concesión de licencias ambientales. Los estudios ambientales y sus evaluaciones técnicas se basan en supuestos cuestionables y a menudo carecen de datos de referencia precisos. La falta de recursos públicos para la investigación independiente hace que las agencias ambientales dependan de los servicios y de la información proporcionada por las compañías mineras. Aparte de esta forma de colaboración, la prioriz
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- 2018
113. Mining Projects and Socio-environmental Factors that Weaken Campesino (peasant) Communities in the Central Andes of Peru
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Quispe-Zuniga, Melissa R., Ortiz-Quispe, Carlos M., Plasencia, Rommel, Quispe-Zuniga, Melissa R., Ortiz-Quispe, Carlos M., and Plasencia, Rommel
- Abstract
In the central Peruvian Andes, the potential impact of mining and the overlap of mining areas with community lands have caused different impacts, ranging from those affecting the environment to those affecting the community institution. The objective of this study is to analyse the socio-environmental factors that would weaken the campesino (peasant) communities of Huasicancha and Chongos Alto in the central Andes. The current case study is based on mixed methods, including in-depth interviews with open-ended questions and non-participant observation from November 2016 to July 2017. In total, 50 stakeholders (e.g. community members, state institutions, mining companies, etc.) were interviewed. This study found that both communities face socio-environmental factors such as the (economic and environmental) influence of mining projects, the economic influence of social programs, the state institutions, the lack of interest of community members in community activities, the pre-existent territorial conflicts, lack of job opportunities and the decline of farming production. These socio-environmental factors have weakened the campesino community as institution., El potencial minero y la consecuente inversión minera en los Andes centrales del Perú y su superposición con tierras comunales han generado consecuencias que van desde el impacto en el medio ambiente hasta significativos cambios en la comunidad campesina como institución. El objetivo del presente estudio es analizar los factores socio-ambientales que debilitarían las comunidades campesinas de Huasicancha y Chongos Alto, en los Andes centrales del Perú. El presente caso de estudio se basó en métodos mixtos para ambas comunidades, incluyendo entrevistas abiertas, participación en actividades de la comunidad y observación desde noviembre de 2016 a julio de 2017. Se entrevistaron a 50 actores involucrados (e.g., comuneros, instituciones del gobierno, proyectos mineros, entre otros). Esta investigación encontró que ambas comunidades campesinas se enfrentan a problemas socio-ambientales, como la influencia de los proyectos mineros y sus intereses económicos, la inserción de programas sociales ejecutados por el Estado peruano, la relación que existe entre las instituciones estatales y las comunidades, el desinterés de los comuneros en la dinámica de su propia comunidad, el conflicto de la demarcación territorial pre-existente, la falta de oportunidades laborales, y la disminución de la producción agrícola. Por ello, la influencia de dichos factores socio-ambientales (externos e internos) ha desencadenado el debilitamiento de las comunidades campesinas como institución fundamental de la sierra peruana.
- Published
- 2018
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