Journal articles: 'Niobium'

1

Liu, Shuang, Lang Yang, Hao Yi, and Shaoxian Song. "Simultaneous Recovery of Niobium and Sulfur from Carbonate Niobite Ore with Flotation." Minerals 12, no. 4 (March 31, 2022): 432. http://dx.doi.org/10.3390/min12040432.

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Exploring new ways to acquire niobium resources is essential to resolve niobium supply risks, due to the fact that, at present, 99% of niobium is controlled by only two countries. In the present work, a flotation technique was applied to separate niobium from low-grade niobite ore. To maximize the utilization of the original ore resources, pre-flotation was conducted to recover sulfur and eliminate the adverse effects of sulfide on niobite flotation. The obtained sulfur grade and recovery were 33.74% and 92.04%, respectively, and its concentration ratio was 40x. As for the niobite flotation, a closed-circuit experiment with one rougher flotation, three cleaner flotations, and two scavenger flotations was carried out to achieve the maximum niobite recovery. To further improve the niobite recovery, a leaching process with diluted HCl was employed; the final obtained Nb2O5 grade and recovery were 30.19% and 65.04%, respectively, and the concentration ratio reached 242x. Moreover, the economic evaluation implies that the flotation process can attract great positive interest.

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Papulovskiy, Evgeny, Aleksandr Shubin, and Olga Lapina. "Theoretical Modeling Of The Structure Of Surface Niobium Sites Based On Solid-State 93nb Nmr." Siberian Journal of Physics 11, no. 2 (June 1, 2016): 77–91. http://dx.doi.org/10.54362/1818-7919-2016-11-2-77-91.

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In this work niobium oxide clusters on the surface of Al2O3 are modeled using DFT calculations. 93Nb NMR parameters of modeled clusters were computed with the GIPAW method. The niobia system under consideration represents high niobium loading on the surface of the support. The niobium atoms are highly coordinated and linked to the other niobia polyhedra by one or two bonds. The most of the niobium oxide particles has a coordination number of six. The correlations found between 93Nb NMR parameters and coordination environment are discussed.

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Prasetyoko, Didik, Zainab Ramli, Salasiah Endud, and Hadi Nur. "Characterization and Catalytic Performance of Niobic Acid Dispersed over Titanium Silicalite." Advances in Materials Science and Engineering 2008 (2008): 1–12. http://dx.doi.org/10.1155/2008/345895.

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Niobic acid,Nb2O5⋅nH2O, has been supported on the titanium silicalite by impregnation method. The obtained materials were characterized by X-ray diffraction, infrared, and ultra-violet—visible diffuse reflectance spectroscopy, temperature programmed reduction, pyridine adsorption, and field emission scanning electron microscopy techniques. It was demonstrated that the tetrahedral titanium species still retained after impregnation of niobic acid. The results revealed that niobium species interacted with hydroxyl groups on the surface of TS-1. The niobium species in the catalysts are predominantly polymerized niobium oxides species or bulk niobium oxide with the octahedral structure. All catalysts showed both Brønsted and Lewis acid sites. The catalysts have been tested for epoxidation of 1-octene with aqueous hydrogen peroxide. It was found that the presence of niobic acid in the catalysts enhanced the rate of the formation of epoxide at the initial reaction time. Diol as a side product was also observed due to the acidic properties of the catalysts.

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Habazaki, H., M. Yamasaki, T. Ogasawara, K. Fushimi, H. Konno, K. Shimizu, T. Izumi, R. Matsuoka, P. Skeldon, and G. E. Thompson. "Thermal degradation of anodic niobia on niobium and oxygen-containing niobium." Thin Solid Films 516, no. 6 (January 2008): 991–98. http://dx.doi.org/10.1016/j.tsf.2007.06.127.

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5

Bliznyuk, Antonina, and Valentin Kozin. "NIOBIUM’S BEHAVIOR IN AQUEOUS HYDROFLUORIC ACID SOLUTION." Ukrainian Chemistry Journal 87, no. 8 (September 24, 2021): 116–26. http://dx.doi.org/10.33609/2708-129x.87.08.2021.116-126.

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Thanks to the unique combination of physicochemical properties, niobium and its compounds are widely used in various fields of science and technology. The main areas of niobium’s applications are the production of superconductors, nuclear energy, chemical engineering, metallurgy, manufacture of optically active materials, thin-film lithium batteries, fuel cells. The aim of this work is to study the processes that take place on the niobium electrode in aqueous solutions of hydrofluoric acid, as well as to establish the composition of niobium compounds that are formed. The paper presents the results of studies the behavior of the niobium electrode in aqueous solutions 0.25 N. hydrofluoric acid. The kinetic parameters of the processes occurring at the phase boundary are determined. It was found that the anodic polarization of the niobium electrode is accompanied by the formation of a passive layer, the destruction of which is facilitated by increasing the polarization potential and fluorine anions, in the presence of which complex fluoroiobate anions [NbF7]2- and [NbOF5]2-are formed. Cathodic polarization of niobium is accompanied by the formation of hydrides on its surface, which causes an increase in the overvoltage of hydrogen evolution. The anodic polarization of the niobium electrode in a solution of hydrofluoric acid causes the formation on its surface of a passive layer, which is destroyed with increasing potential. In the Nbo–NbO2–0.25 –0.25 n HF system, [NbF7]2-anions are formed, as evidenced by bands in the region of 500 nm on the electron absorption spectra. The rate constants of [NbF7]2- and [NbOF5]2- formation are estimated at 3.78 • 10-3 s-1 and 5.18 • 10-3 s-1, respectively. The reduction of hydrogen at the niobium cathode from a solution of hydrofluoric acid is accompanied by the formation of hydrides, which causes an increase in the overvoltage of hydrogen evolution and high values of the angular coefficients of the Tafel dependence.

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6

Eckert,, J. "Niobium and Niobium Compounds." High Temperature Materials and Processes 11, no. 1-4 (January 1993): 97–118. http://dx.doi.org/10.1515/htmp.1993.11.1-4.97.

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7

Leont’ev, L. I., V. I. Zhuchkov, O. V. Zayakin, A. V. Sychev, and L. Yu Mikhailova. "Potential for obtaining and applying complex niobium ferroalloys." Izvestiya. Ferrous Metallurgy 65, no. 1 (February 11, 2022): 10–20. http://dx.doi.org/10.17073/0368-0797-2022-1-10-20.

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This paper provides information regarding the application of niobium in industry and the scale of its production in the world and the Russian Federation. Most of the niobium deposits in Russia consist of pyrochlore, apatitepyrochlore and columbitepyrochlore types of ores. They contain a significant amount of phosphorus. Therefore, all enrichment schemes for these ores contain a dephosphorization stage which increases the price of the product and reduces the degree of niobium extraction. The paper explores the possibility of improving the end-to-end production scheme: niobium ore – beneficiation – niobium ferroalloy. The bulk of ferroniobium is intended for steel microalloying and can be replaced by complex ferroalloys with a reduced niobium content. The paper considers the issues of obtaining complex niobium ferroalloys from a rough concentrate with a weak content of niobium. It has been established that the addition of 25 – 40 % of silicon or 12 – 30 % of aliminum to the twocomponent metal system Fe – Nb causes the transfer of niobium ferroalloys (15 – 20 % Nb) from the refractory category to lowmelting materials. The crystallization temperatures are less than 1400 °C. The substantiation of using a complex niobium ferroalloy instead of ferroniobium is given. This alloy has reduced niobium content and increased silicon or aluminum content. Higher service characteristics of the complex ferroalloy are noted in comparison with ferroniobium (temperature of the initiation of crystallization and density). They indicate an increased assimilation of niobium when using a complex ferroalloy for steel microalloying. The paper presents data on the possibility of dephosphorization of niobium concentrates in the process of pyrometallurgical production of a complex ferroalloy. An improved scheme for the production of niobiumcontaining ferroalloys is proposed. This consists of the use of niobium concentrate for melting the intermediate ferroalloy containing a reduced concentration of niobium oxides and an increased concentration of silicon (aluminum). This ferroalloy can be used effectively for steel microalloying with niobium.

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8

Störmer, H., E. Ivers-Tiffée, C. Schnitter, and D. Gerthsen. "Microstructure and dielectric properties of nanoscale oxide layers on sintered capacitor-grade niobium and V-doped niobium powder compacts." International Journal of Materials Research 97, no. 6 (June 1, 2006): 794–801. http://dx.doi.org/10.1515/ijmr-2006-0128.

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Abstract Electrolytic anodization was used to form amorphous niobium oxide layers on niobium and V-doped niobium powder compacts which act as dielectric layers, e. g. in niobium-based solid electrolyte capacitors. The microstructure development within the layered structure niobium-niobium oxide was studied by scanning- and transmission electron microscopy in order to investigate the influence of processing parameters. It could be shown that the thickness as well as the quality of the oxide layers on niobium vary in a considerable range, depending on processing parameters. Examination of the influence of heat treatments on the structural properties of the oxide layers revealed remarkable changes at the niobium – niobium oxide interface upon heat impact exceeding 300 °C. In contrast, the interface remains stable with respect to the as-anodized sample when annealing was performed at lower temperature.

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9

Liu, Cheng Jun, Ya He Huang, Hong Liang Liu, and Mao Fa Jiang. "Effects and Mechanisms of Niobium on the Fracture Toughness of Heavy Rail Steel." Advanced Materials Research 163-167 (December 2010): 110–16. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.110.

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Heavy rail steel was prepared by the process of vacuum induction furnace smelting, forge work and rolling. Effects and mechanisms of niobium on the fracture toughness of heavy rail steel were investigated. In addition, the appropriate range of niobium content for heavy rail steel was determined. With the niobium content increasing, both the austenite grain size and pearlite laminae distance of heavy rail steel were decreased gradually at first and then increased rapidly. When the niobium content was low, the precipitates containing niobium predominantly appeared in the cementite, which improved the toughness of heavy rail steel by fining the austenite grain size and pearlite laminae distance; when the niobium content > 0.024%, the fine dispersed precipitates containing niobium mainly occurred in the ferrite, which improved the toughness of heavy rail steel by pining dislocations and inhibiting crack growth; with the niobium content increasing, both the quantity and size of precipitates containing niobium were increased gradually; when the niobium content > 0.073%, most precipitates containing niobium could not pin dislocations and inhibit crack growth because the particles size was too big, thus the fracture toughness of heavy rail steel was bad. So the optimum range of the niobium content could improve the fracture toughness of heavy rail steel. In the present study, when the niobium content was about 0.053%, the fracture toughness of heavy rail steel was the best. The maximum plane-strain fracture toughness was 49.88 MPam1/2.

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10

ZURER, PAMELA S. "NIOBIUM." Chemical & Engineering News 81, no. 36 (September 8, 2003): 106. http://dx.doi.org/10.1021/cen-v081n036.p106.

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11

Kee, Terence P. "Niobium." Coordination Chemistry Reviews 127, no. 1-2 (September 1993): 155–70. http://dx.doi.org/10.1016/0010-8545(93)80059-e.

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12

Do, Nascimento, Marques Cury, Campos de, Malpass Pointer, and Roberto Alves. "Production of niobium: Overview of processes from the mine to products." Journal of Mining and Metallurgy A: Mining 58, no. 1 (2022): 1–20. http://dx.doi.org/10.5937/jmma2201001h.

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A number of industrial and technology sectors have been paying attention to a particular chemical element in recent years, namely niobium (Nb). There are many niobium deposits scattered around the world, and for each deposit different technologies are applied for extraction and processing due to the singular characteristics present at each site. In this paper, a review of the many technologies for niobium production will be presented starting at the mine, through techniques of niobium ore beneficiation and refining, technologies to produce ferroniobium alloy, oxides, special oxides, ammonium niobium oxalate, the separation of niobium from tantalum, and techniques to reduce and purify metallic niobium.

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13

Lee, Young Kook, Jin-Myung Hong, Chong Sool Choi, and Jae Kon Lee. "Continuous Cooling Transformation Temperatures and Microstructures of Niobium Bearing Microalloyed Steels." Materials Science Forum 475-479 (January 2005): 65–68. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.65.

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Effects of niobium content and cooling rate on ferrite and bainite start temperatures (Ar3, Bs) and microstructural features have been studied in niobium bearing ultralow carbon microalloyed steels. The Ar3 and Bs temperatures decrease as niobium content or cooling rate is increased. The dependence of Ar3 on cooling rate is greater than that of Bs in all niobium contents. The bainitic ferrite laths become longer and narrower with increasing niobium content and cooling rate, and niobium also shows a tendency to decrease polygonal ferrite grain size.

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14

Vukićević, Nataša M., Vesna S. Cvetković, Ljiljana S. Jovanović, Olga S. Radulović, and Jovan N. Jovićević. "Electrodeposition of Nb and Al from chloroaluminate melt on vitreous carbon." Metallurgical and Materials Engineering 22, no. 2 (June 30, 2016): 91–100. http://dx.doi.org/10.30544/217.

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Niobium and aluminium were electrodeposited at 200 °C under argon atmosphere onto vitreous carbon from inorganic chloroaluminate melts (AlCl3+NaCl) with added niobium. Niobium was introduced into the electrolyte by anodic dissolution of metallic niobium or by chemical dissolution of Nb2O5 in a melt of equimolar AlCl3+NaCl mixture. The processes of deposition/dissolution onto/from vitreous carbon were investigated by cyclic voltammetry and chronoamperometry. Characterization of the obtained deposits was done by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The only observed reduction processes on the working electrode in the potential window from 1.000 V to – 1.000 V vs. Al, were individual niobium deposition and codeposition of niobium and aluminium with Al-Nb alloys formation. Electrodeposition of niobium from the chloroaluminate melt with added niobium (V) oxide seems to start at around – 0.100 V vs. Al and at about – 0.200 V vs. Al aluminium starts codepositing. During the codeposition Nb-Al alloys were formed. Niobium deposition starting potential from the electrolyte with niobium added by anodic dissolution starts at 0.100 V vs. Al, and aluminium codeposition starting potential was at around – 0.025 V vs. Al, followed by Nb/Al alloy formation.

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15

Smirnova, Daria, and Sergey Starikov. "Study of Niobium Diffusion and Clusterization in hcp Zr-Nb Dilute Alloys." Defect and Diffusion Forum 375 (May 2017): 167–74. http://dx.doi.org/10.4028/www.scientific.net/ddf.375.167.

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We perform atomistic simulations aimed on study of diffusion of constituents and niobium precipitation in hcp Zr-Nb. We report diffusivities of Zr and Nb in hcp Zr-Nb alloys computed for the models containing up to 5 at.% of niobium. The calculated diffusivity of niobium rises with increase of its content in the alloy. The simulations also show that for a studied concentration range addition of niobium slightly enhances self-diffusion of zirconium in the alloys. The work is also devoted to description of niobium incorporation and clusterization in hcp zirconium. It is confirmed that for a single niobium atom incorporated in hcp zirconium lattice the octahedral position is the most favorable. We estimated the energy describing niobium cluster formation in pure hcp zirconium. According to the simulation results, we can suggest that the minimum niobium cluster size that can be expected in hcp Zr corresponds to about 80 atoms.

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16

Ismagulova, М. Sh, Kh R. Маylina, А. К. Serikpayeva, and А. V. Panichkin. "Study of hydrogen dilation of membranes based on transition metals." Engineering Journal of Satbayev University 144, no. 1 (2022): 24–30. http://dx.doi.org/10.51301/ejsu.2022.i1.04.

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Niobium absorbs hydrogen well, which is accompanied by structural and phase changes in the metal. To study the phenomenon of "hydrogen embrittlement" in niobium, the work presents studies of the dilatation of samples of pure niobium and palladium-coated niobium foil at different pressures in a gaseous medium. Hydrogen dilatation measurements were carried out on a setup developed based on a Shimadzu AG 100kNx electromechanical testing machine. A series of experiments to study the deformation of niobium membranes was carried out in two stages. At the first stage, pure niobium samples were studied; at the second stage, niobium samples palliated on both sides were studied. An oxide film on the surface of niobium significantly reduces the rate of diffusion of hydrogen atoms into the bulk of the sample, which leads to the development of slow dilatation in niobium in a hydrogen atmosphere. The deposition of a catalytic palladium film on the niobium surface provides a hundreds-fold increase in the flow rate of hydrogen atoms into the sample volume. It has been proved that it is advantageous for hydrogen to occupy tetrahedral positions in the niobium lattice. To study the strain rate and detect points of phase transitions, isobars for niobium and tantalum were plotted. Based on the isobar analysis, the linear thermal expansion coefficient of Nb and Ta was calculated. A rearrangement of the crystal lattice of the base metal in the region of high temperatures, accompanied by a change in the symmetry of the structure of the substance, has been found.

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Liu, Ao, Wenrou Su, and Jie Wu. "Main applications and characterization of world resources of niobium and progress in extraction." E3S Web of Conferences 520 (2024): 03026. http://dx.doi.org/10.1051/e3sconf/202452003026.

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This paper focuses on niobium applications in the steel industry, aerospace industry, electronics industry, superconducting alloys, medical and other fields. As the demand of niobium resources is increasing year by year, this paper also introduces the distribution and characteristics of niobium resources in the world, and the characteristics of niobium resources in Bayan Obo. As well as the current situation and main methods of niobium resources development and utilization.

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18

Fateev, Sergei Anatol'evich, Elena Konstantinovna Tuseeva, and Aleksandr Mordukhaevich Skundin. "Current leads corrosion and the problem of diagnostics of fluorocarbon-lithium cells." Electrochemical Energetics 10, no. 4 (2010): 182–86. http://dx.doi.org/10.18500/1608-4039-2010-10-4-182-186.

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Corrosion behavior of niobium current leads of fluorocarbon-lithium cells are studied. Polarization measurements at plain niobium leads and at such leads in a contact with fluorocarbon cathode in an electrolyte of fluorocarbon-lithium cell were carried out. Besides, behavior of niobium lead directly in a feedthrough of real cells was studied. The contact of niobium with fluorocarbon cathode is shown to result in toughening of corrosion conditions and in possible niobium depassivation. Long-term cells storage at elevated temperature was shown to result in complete corrosion dissolution of niobium leads. Certain correlation between cell's OCV and corrosion intensity was obtained.

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19

Heslinga, D. R., W. M. Van Huffelen, and T. M. Klapwijk. "Electron transport in niobium-silicon-niobium structures." IEEE Transactions on Magnetics 27, no. 2 (March 1991): 3264–67. http://dx.doi.org/10.1109/20.133908.

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20

Sheppard, L. R., A. J. Atanacio, T. Bak, J. Nowotny, M. K. Nowotny, and K. E. Prince. "Niobium diffusion in niobium-doped titanium dioxide." Journal of Solid State Electrochemistry 13, no. 7 (November 6, 2008): 1115–21. http://dx.doi.org/10.1007/s10008-008-0717-x.

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21

Smid, Ivi, and Gaurav Aggarwal. "Powder Injection Molding of Niobium." Materials Science Forum 475-479 (January 2005): 711–16. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.711.

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Niobium and niobium-based alloys are used in a variety of high temperature applications ranging from light bulbs to rocket engines. Niobium has excellent formability and the lowest specific weight among refractory metals (Nb, Ta, Mo, W, and Re). Powder injection molding of niobium powder was investigated for efficiency of the process. The sintering of injection molded bars was conducted up to 2000°C in vacuum and low oxygen partial pressure atmosphere. This paper investigates the effect of sintering time, temperature and atmosphere on processing of pure niobium.

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22

Zhang, Bo, and Mao Fa Jiang. "Study on Separation of Niobium and Iron from Low Grade Niobium Ore." Advanced Materials Research 524-527 (May 2012): 2044–48. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.2044.

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The separation of niobium and iron from the low grade niobium ore was researched by the technology process of reductive roasting and magnetic separation. Experiments of reductive roasting and magnetic separation were carried out in order to investigate the separation effect at different conditions of roasting temperature and addition amount of coal powders. The results show that the separation of niobium and iron can be realized, meanwhile the niobium can be enriched in the magnetic tailings. The main mineral phase of niobium in magnetic tailings changes into NbC from (Ce,Nd)NbTiO5when the roasting temperature exceeds 1150°C. By magnetic separation after roasting with adding 37.5% coal powders at 1050°C, w(T.Fe) of the reduced iron is 86.11%, the percentage metallization is 87.6%, and the yield ratio of iron is 77.4%. Meanwhile, w(Nb2O5) of the magnetic tailings is 7.35% which is 2.4 times higher than low grade niobium ore, and the yield ratio of niobium is 98.1%.

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23

Zhou, Zhu-Hua, Sheng-Qiang Song, Robert Cromarty, Yi-Liang Chen, and Zheng-Liang Xue. "The Precipitation of Niobium Carbide and Its Influence on the Structure of HT250 for Automobile Wheel Hubs." Materials 14, no. 20 (October 15, 2021): 6109. http://dx.doi.org/10.3390/ma14206109.

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Improving the strength of grey cast iron wheel hubs will improve the safety of automobiles and have a great significance for energy saving and environmental protection. This paper systematically compares the calculation results of Python-based precipitation calculation and JmatPro software simulation with experiments. The results show that with a low mass fraction of niobium (0.098%) cuboid Niobium Carbide (NbC) precipitates do not form in the liquid phase; however, an elongated NbC niobium-rich phase may form during the solidification process and in the solid phase. However, cuboid NbC precipitates can be precipitated from the liquid phase when the niobium mass fraction is higher (0.27%, 0.46%). These results indicate that with the increasing niobium content the amount, particle size, and initial precipitation temperature of niobium carbide precipitated in the matrix structure will increase. According to the observation and statistical analysis of the microstructure, it is found that tensile strength will be improved with an increase in niobium content due to the refinement of the graphite and pearlite interlamellar spacing. In this paper, adding less than 0.32% of Nb to grey cast iron is recommended, considering the comprehensive cost and the effect of niobium in the material structure.

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Sankar, M., K. V. Mirji, V. V. Satya Prasad, R. G. Baligidad, and A. A. Gokhale. "Purification of Niobium by Electron Beam Melting." High Temperature Materials and Processes 35, no. 6 (June 1, 2016): 621–27. http://dx.doi.org/10.1515/htmp-2014-0218.

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AbstractPure niobium metal, produced by alumino-thermic reduction of niobium oxide, contains various impurities which need to be reduced to acceptable levels to obtain aerospace grade purity. In the present work, an attempt has been made to refine niobium metals by electron beam drip melting technique to achieve purity confirming to the ASTM standard. Input power to the electron gun and melt rate were varied to observe their combined effect on extend of refining and loss of niobium. Electron beam (EB) melting is shown to reduce alkali metals, trace elements and interstitial impurities well below the specified limits. The reduction in the impurities during EB melting is attributed to evaporation and degassing due to the combined effect of high vacuum and high melt surface temperature. The % removal of interstitial impurities is essentially a function of melt rate and input power. As the melt rate decreases or input power increases, the impurity levels in the solidified niobium ingot decrease. The EB refining process is also accompanied by considerable amount of niobium loss, which is attributed to evaporation of pure niobium and niobium sub-oxide. Like other impurities, Nb loss increases with decreasing melt rate or increase in input power.

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Şen, Uğur, and Şaduman Şen. "Characterization of Niobium Carbonitride Coating on AISI D2 Steel." Materials Science Forum 554 (August 2007): 213–17. http://dx.doi.org/10.4028/www.scientific.net/msf.554.213.

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Thermo-diffusion coatings containing Nitrogen, Carbon and Niobium (N+C+Nb) on AISI D2 steel have been carried out by an initial tufftriding process followed by saturation with Niobium. The properties of the diffusion layer, namely microstructure, phase composition and micro-hardness of the Niobium carbonitride layer, have been studied. The influence of treatment time of Niobizing on the thickness of the metallized layer and its phase composition has been studied. Nitriding treatment was performed at 575°C for 2 h. Then, the Niobizing treatment was performed by pack method in the powder mixture consisting of ferro-Niobium, ammonium chloride and alumina at 1000°C for 1–4 h. The phases formed on the Niobium carbonitride coated steel were NbN and NbC, confirmed by X-ray diffraction (XRD) analysis. The longer the treatment times, the thicker the Niobium carbonitride layer became. The thickness of Niobium carbonitride layer was changing between 6.53 3m and 17.45 3m, depending on treatment time and temperature. The microhardness of Niobium carbonitride layer formed on the AISI D2 steel was changing between 2132±203 and 2814±245 HV0.01 from surface to interior.

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Kucera, Benjamin E., Christopher J. Roberts, Victor G. Young, William W. Brennessel, and John E. Ellis. "Niobium isocyanide complexes, Nb(CNAr)6, with Ar = 2,6-dimethylphenyl (Xyl), a diamagnetic dimer containing four reductively coupled isocyanides, and Ar = 2,6-diisopropylphenyl (Dipp), a paramagnetic monomer analogous to the highly unstable hexacarbonylniobium(0)." Acta Crystallographica Section C Structural Chemistry 75, no. 9 (August 14, 2019): 1259–65. http://dx.doi.org/10.1107/s205322961901101x.

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Treatment of bis(mesitylene)niobium(0) with 6–7 equivalents of 2,6-dimethylphenyl isocyanide (CNXyl) affords two products with the empirical formula Nb(CNXyl) n (n = 7 or 6), which have been shown to be the diamagnetic dimers bis[μ-N,N′,N′′,N′′′-tetrakis(2,6-dimethylphenyl)squaramidinato(2−)]bis[pentakis(2,6-dimethylphenyl isocyanide)niobium(I)], [Nb2(C9H9N)10(C36H36N4)] or [Nb(CNXyl)5]2[μ-C4(NXyl)4]·xSolvent, 1, and bis[μ-N,N′,N′′,N′′′-tetrakis(2,6-dimethylphenyl)squaramidinato(2−)]bis[tetrakis(2,6-dimethylphenyl isocyanide)niobium(I)] tetrahydrofuran trisolvate, [Nb2(C9H9N)8(C36H36N4)]·3C4H8O or [Nb(CNXyl)4]2[μ-C4(NXyl)4]·3THF (THF = tetrahydrofuran), 2. Each contains NbI bound to either five or four terminal isocyanides, respectively, and to an unprecedented bridging tetraarylsquaramidinate(2−) unit, coordinated as a bidentate ligand to each niobium center, symmetrically due to the crystallographic inversion center that coincides with the centroid of the central C4 unit. Thus, in the presence of CNXyl, the bis(mesitylene)niobium(0) is oxidized to niobium(I), resulting in the facile loss of both mesitylene groups and the reductive coupling of two CNXyl groups per niobium to provide the first examples of tetraarylsquaramidinate(2−) ligands, [cyclo-C4N4Ar4]2−, coordinated to metals. In contrast, bis(mesitylene)niobium(0) reacts with the more crowded 2,6-diisopropylphenyl isocyanide (CNDipp) to afford the paramagnetic monomer hexakis(2,6-diisopropylphenyl isocyanide)niobium(0), [Nb(C13H17N)6] or Nb(CNDipp)6, 3, the first zero-valent niobium isocyanide analog of the highly unstable Nb(CO)6, which is presently only known to exist in an argon matrix at 4.2 K.

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Ultarakova, Almagul, Zaure Karshyga, Nina Lokhova, Azamat Yessengaziyev, Kaisar Kassymzhanov, and Arailym Mukangaliyeva. "Studies of Niobium Sorption from Chloride Solutions with the Use of Anion-Exchange Resins." Processes 11, no. 4 (April 21, 2023): 1288. http://dx.doi.org/10.3390/pr11041288.

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This paper presents the results of studies for niobium sorption from chloride solutions with the use of anion-exchange organic sorbents: Amberlite IRA-67, Purolite A-100, AB-17-8, and AN-2FN. Niobium sorption was performed from model niobium-containing solutions. Data on comparative sorption characteristics of the studied sorbents were obtained, and the static exchange capacity of the sorbents, values of distribution coefficients, and extraction degree during the niobium sorption from chloride solutions were calculated. The Purolite A-100 anion-exchange resin exhibited the highest affinity for niobium ions under the conditions studied. Its distribution coefficient was 184 mL/g; the niobium extraction degree was 41.5%. To study the equilibrium sorption of niobium from solution on the Purolite A-100 anionite, three well-known models of isotherms were applied: Langmuir, Freundlich, and Dubinin–Radushkevich. The data obtained confirm the good agreement of the Langmuir model with the results of experiments and indicate that the process takes place in a monomolecular layer on the adsorbent having homogeneous adsorption centers. The optimum conditions of niobium sorption by the Purolite A-100 anion-exchange resin were determined as follows: hydrochloric acid concentration—5–10 wt.%, process temperature—35–40 °C, and duration—40–50 min. The calculated activation energy values for niobium sorption from hydrochloric acid solution in the temperature range of 20–50 °C were 25.32 kJ/mol, which corresponds to the intermediate region corresponding to the transition from the diffusion to the kinetic mode.

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Irfan, Muhammad, Muhammad Ahmad, Sadia Akhtar, Muhammad Khan, and Muhammad Khan. "Experimental and statistical study for leaching of niobium pentoxide from Pakistani ore." Chemical Industry and Chemical Engineering Quarterly 24, no. 1 (2018): 51–58. http://dx.doi.org/10.2298/ciceq160518018i.

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The growing demand for niobium pentoxide, based on its use in separation processes, established its prominent significance as a leading candidate in the field of separation science and technology. This study reports the extraction of niobium pentoxide from pyrochlore ore occurring in Sillai Patai, KPK, Pakistan. It is difficult to recover niobium pentoxide from Pakistani ore due to its low concentration. Niobium pentoxide is an important material used in manufacturing industries for different purposes. Most of the commercially employed extraction processes are associated with serious environmental impacts and are not efficient in extracting niobium pentoxide from low concentration pyrochlore. Alkali potash has been used for separation and purification of niobium pentoxide because it is efficient and an environmentally friendly process. The leaching of niobium pentoxide is carried out in a batch reactor using alkali potash as a leachant. Various process parameters, including ore particle size, reaction temperature, reaction time and alkali to ore mass ratio, were examined statistically during the leaching process. It was observed that reaction temperature and ore particle size were more significant compared to other parameters. The maximum percent recovery of niobium pentoxide (95%) was obtained at 280?C in 90 min, while keeping the ore particle size 44 ?m and alkali to ore mass ratio of 7:1.

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de Macêdo Neto, José Costa, Marcelo Duarte Vieira, Ana Emília Diniz Silva Guedes, João Evangelista Neto, Bruno Mello de Freitas, Guilherme Santos Moreira, Lucas Carvalho Cruz, et al. "Effect of Niobium and Heat Treatment on the Microstructure and Mechanical Properties of SAE 8620 Steel." Materials Science Forum 930 (September 2018): 327–32. http://dx.doi.org/10.4028/www.scientific.net/msf.930.327.

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An interest in the search for materials with reduced thicknesses, high mechanical resistance and low density has been increasing by the industry. The addition of niobium in micro-alloyed steels in the automotive industry is an alternative for obtaining light and resistant materials. The objective of this work was to verify the influence of the niobium and the heat treatment of normalizing in the microstructure and hardness of the steel SAE 8620. Also the behavior of the cementation in the steel was studied. It was verified that the removal of the normalization heat treatment did not affect the microstructure and the hardness of the steel with the niobium in relation to the steel without niobium and normalization. The cemented layer for the steel with niobium presented a greater microhardness to the depth in relation to steel without niobium.

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30

Zhong, Liang, and Gaik-Khuan Chuah. "Fischer Indole Synthesis over Hydrous Zirconia-Supported Niobium Oxide." Australian Journal of Chemistry 62, no. 9 (2009): 1027. http://dx.doi.org/10.1071/ch09237.

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Supported niobium oxides are investigated as green catalysts for Fischer indole reaction. By means of wet impregnation, 10–40 wt-% Nb2O5 were loaded onto hydrous zirconia as a support. Pore size distribution curves showed that the niobium oxide overlayer was uniformly dispersed onto the mesoporous support. Samples with close to a monolayer coverage of niobium oxide had the highest activity in the Fischer indole reaction of phenylhydrazine with both 3-heptanone and cyclohexanone. A coverage higher than a monolayer led to lower activity. In comparison, the supported catalysts were more active than bulk niobium oxide or a sample prepared by co-precipitation of hydrous zirconia and niobium oxide.

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31

Вayrachniy, B. I., and I. A. Tokareva. "Nanostructured Anodic Oxide Films of Niobium: Features of Electrochemical Formation, Functional Properties and Applications (Review)." Фізика і хімія твердого тіла 17, no. 2 (June 15, 2016): 160–69. http://dx.doi.org/10.15330/pcss.17.2.160-169.

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The review summarizes data on the anodic behavior of niobium in aqueous solutions. Features of electrochemical formation nanostructured oxide coatings on niobium by anodic oxidation are systematized. The article deals with theoretical aspects formation of the porous anodic oxide layers. The influence of process parameters and the characteristics of the electrolyte on layer of niobium oxide were analyzed. The functional properties of porous coating on niobium are considered and promising areas of practical application identified.

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32

Mei, Paulo Roberto. "Effects of Niobium Microaddition on Carbon Steels." Defect and Diffusion Forum 420 (November 14, 2022): 101–17. http://dx.doi.org/10.4028/p-5kc1x5.

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Niobium is added to carbon steels in small amounts (< 0.1weight %), thus being called a microalloying element, to increase mechanical strength and toughness. When added to steel, niobium is partly soluble in the matrix and another part combines with carbon and nitrogen forming a family of NbxCyNz precipitates (niobium carbides, nitrides or carbonitrides), where the values of x, y, z depend on the temperature and the chemical composition of the steel. The effects of niobium dissolved in the matrix or as precipitates are distinct and sometimes antagonistic. Thus, two samples of the same carbon steel microalloyed with niobium may differ in: microstructure, ferritic grain size or interlamellar spacing of the pearlite, depending on the thermomechanical processing to which they were submitted, which will result in different mechanical properties. In order to make good use of the possible beneficial effects of adding niobium to carbon steels, it is necessary to clearly understand its complex physical metallurgy. To analyze the effects of niobium, six steels were used (0.2/0.4/0.8 C/ 1 Mn, with and without the addition of 0.03 Nb, weight %). Using an ARL ion microprobe, with oxygen ions and mass spectroscopy reading on niobium steel, after partial isothermal transformation at 700 oC, we observed the partition of niobium between ferrite and austenite. Thus, the formation of ferrite is slower, shifting the TTT curve to longer times and separating the pearlite and bainite bays. The same occurs in continuous cooling transformation, where the diffusional components (ferrite, pearlite and bainite) are formed at lower temperatures and with a longer time. With pearlite forming at lower temperatures, there is a decrease in the interlamellar spacing, increasing its hardness and, consequently, the mechanical strength. Niobium also forms carbonitrides, and these finely precipitated particles anchor the grain boundary, making it difficult to move and thus producing a smaller austenitic grain size than in steel without the addition of niobium, increasing mechanical strength and toughness of steel.

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33

Abdul Majid, Rafdi, Sulaksana Permana, Johny Wahyuadi Soedarsono, Wahyu Kartika, Munira Munira, D. Darnengsih, and M. Mustafiah. "Peningkatan Kadar Tantalum dan Niobium Oksida dari Terak Timah Bangka Menggunakan Pelarut NaOH dilanjutkan HNO3 dan H3PO4." Journal of Chemical Process Engineering 4, no. 2 (November 20, 2019): 83–89. http://dx.doi.org/10.33536/jcpe.v4i2.468.

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Terak Timah merupakan produk samping dari proses peleburan timah yang mengandung unsur logam tantalum dan niobium. Beberapa sumber unsur tantalum dan niobium yaitu columbite, tantalite, tantalo-columbite, dll. Tantalum & niobium memiliki banyak aplikasi seperti industri pesawat terbang, elektronik dan super alloy. Penelitian ini dilakukan untuk meningkatkan kadar unsur logam tantalum dan niobium dari terak timah melalui proses pelindian asam maupun basa. Hasil penelitian menunjukan bahwa proses pemanggangan yang dilakukan tidak mengalami dekomposisi thermal, selanjutnya proses pelindian basa dengan NaOH mengakibatkan penurunan yang sangat kecil terhadap niobium yaitu dari 0,75 menjadi 0,73%, sedangkan proses pelindian dengan HNO3 dan H3PO4 memberikan peningkatan terhadap tantalum dan niobium yaitu dengan HNO3 2M menghasilkan Ta dan Nb berturut-turut 0,17 menjadi 0,85 dan 0,73 menjadi 1,49. Hal ini juga terlihat pada pelindian menggunakan campuran HNO3: H3PO4 menghasilkan peningkatan Ta dan Nb berturut-turut menjadi 0,88-0,9% dan 1,46-1,54% di setiap peningkatan variasi konsentrasi H3PO4

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34

Sakaki, Hayato, Masayuki Mizumoto, Takeshi Ohgai, and Akio Kagawa. "New Application of High Niobium Cast Iron as a Grain Refiner for Stainless Steels." Key Engineering Materials 457 (December 2010): 447–52. http://dx.doi.org/10.4028/www.scientific.net/kem.457.447.

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In order to develop a new application of cast iron, high niobium cast iron has been developed as a grain refiner for stainless steel. High niobium cast iron was prepared by adding pure niobium to a commercial cast iron. Coarse primary niobium carbide crystals were observed in the microstructure of the cast iron. The effect of the high niobium cast iron as an inoculant on the grain size of austenitic and ferritic stainless steels was examined in various experimental conditions. When the amount of the cast iron inoculant more than 3 mass% was added into the steel melt, fine equiaxed grains were observed and grain size was significantly reduced to 210 μm. The results indicate that the high niobium cast iron is effective as a grain refiner for the austenitic and ferritic stainless steels. From the dissolution rate measurement, the grain refining mechanism was proposed.

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35

Okunev, M. A., and S. A. Kuznetsov. "Electrode processes during electrodeposition, electropolishing and oxidation of niobium." Transaction Kola Science Centre 12, no. 2-2021 (December 13, 2021): 192–96. http://dx.doi.org/10.37614/2307-5252.2021.2.5.040.

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The electrode processes occurring during the electrodeposition, electropolishing and oxidation of niobium are considered. The discharge of Nb(IV) complexes during Nb electrodeposition was studied by cyclic voltammetry. The anodic polarization curve on niobium in a mixture of acids H2SO4:HF (9:1) was obtained by chronopotentiometry method, the potential range at which the highest quality and speed of electropolishing is achieved was found. The film formation mechanism of niobium pentoxide Nb2O5 on niobium was studied by cyclic voltammetry.

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36

Fu, Xiaoguo, Kezhao Liu, Xiaolin Wang, Zhengping Zhao, and Yong Yu. "X-Ray Photoelectron Spectroscopic Study of the Surface Reaction of Uranium–Niobium Alloy with O2." Surface Review and Letters 10, no. 02n03 (April 2003): 381–86. http://dx.doi.org/10.1142/s0218625x03004767.

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The initial oxidation of uranium–niobium alloy in oxygen atmosphere at 298 K has been studied by X-ray photoelectron spectroscopy (XPS). For comparison, the adsorption of oxygen on pure metal niobium and uranium has also been studied. The changes of U4f, Nb3d and O1s spectra during in situ oxidation indicate that the adsorption of oxygen on uranium–niobium alloy surfaces first leads to the formation of UO2 and NbO; then NbO2 and Nb2O5 are detected with increasing exposures of oxygen. The segregations of U and Nb to the uranium–niobium alloy surfaces are observed at different oxidation stages. The oxide film formation of uranium–niobium alloy is faster than that of pure uranium at initial oxidation stages.

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37

Jaworska, Lucyna, Tomasz Skrzekut, Michał Stępień, Paweł Pałka, Grzegorz Boczkal, Adam Zwoliński, Piotr Noga, Marcin Podsiadło, Radosław Wnuk, and Paweł Ostachowski. "The Pressure Compaction of Zr-Nb Powder Mixtures and Selected Properties of Sintered and KOBO-Extruded Zr-xNb Materials." Materials 14, no. 12 (June 9, 2021): 3172. http://dx.doi.org/10.3390/ma14123172.

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Materials were obtained from commercial zirconium powders. 1 mass%, 2.5 mass% and 16 mass% of niobium powders were used as the reinforcing phase. The SPS method and the extrusion method classified as the SPD method were used. Relative density materials of up to 98% were obtained. The microstructure of the sintered Zr-xNb materials differs from that of the extruded materials. Due to the flammability of zirconium powders, no mechanical alloying was used; only mixing of zirconium and niobium powders in water and isopropyl alcohol. Niobium was grouped in clusters with an average niobium particle size of about 10 μm up to 20 μm. According to the Zr-Nb phase equilibrium system, the stable phase at RT was the hexagonal α-phase. The tests were carried out for materials without the additional annealing process. The effect of niobium as a β-Zr phase stabilizer is confirmed by XRD. Materials differed in their phase composition, and for both methods the β-Zr phase was present in obtained materials. A very favorable effect of niobium on the increase in corrosion resistance was observed, compared to the material obtained from the powder without the addition of niobium.

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38

Hanada, Shuji. "Niobium aluminides." Current Opinion in Solid State and Materials Science 2, no. 3 (January 1997): 279–83. http://dx.doi.org/10.1016/s1359-0286(97)80115-5.

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39

Tarselli, Michael A. "Subtle niobium." Nature Chemistry 7, no. 2 (January 23, 2015): 180. http://dx.doi.org/10.1038/nchem.2164.

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40

Vodárek, Vlastimil, Gabriela Rožnovská, and Jaromír Sobotka. "Microstructure and Creep Properties of AISI 316LN Steels with Niobium Additions." Materials Science Forum 482 (April 2005): 275–78. http://dx.doi.org/10.4028/www.scientific.net/msf.482.275.

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The long-term creep rupture tests have been carried out on three casts of a type AISI 316LN steel at 600 and 650°C. Two of the casts investigated contained additions of 0.1 and 0.3 wt.% of niobium. The growing niobium content strongly reduced the minimum creep rate and prolonged the time to the onset of the tertiary stage of creep and also shortened this stage. The enhanced creep resistance of niobium containing steels is not accompanied by the longer creep life that might have been expected. At both temperatures of creep exposure the niobium-bearing casts displayed an inferior creep ductility. Microstructural investigations revealed that niobium provoked significant grain size refinement and the formation of Z-phase. Particles of this phase were considerably dimensionally stable. Furthermore, niobium accelerated the formation and coarsening of s-phase, h-Laves and M6(C,N). The coarse intergranular particles facilitated the formation of cavities which resulted in intergranular failure mode.

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41

Atanacio, Armand J., Tadeusz Bak, and Janusz Nowotny. "Niobium Segregation in Niobium-Doped Titanium Dioxide (Rutile)." Journal of Physical Chemistry C 118, no. 21 (May 19, 2014): 11174–85. http://dx.doi.org/10.1021/jp4110536.

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42

Teixeira da Silva, V. L. S., E. I. Ko, M. Schmal, and S. T. Oyama. "Synthesis of Niobium Carbide from Niobium Oxide Aerogels." Chemistry of Materials 7, no. 1 (January 1995): 179–84. http://dx.doi.org/10.1021/cm00049a027.

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43

Naka, M., T. Saito, and I. Okamoto. "Niobium silicides at interface between niobium and SiC." Journal of Materials Science Letters 6, no. 8 (August 1987): 875–76. http://dx.doi.org/10.1007/bf01729854.

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44

Fedorov, Vladimir E., Sofya B. Artemkina, Ekaterina D. Grayfer, Nikolay G. Naumov, Yuri V. Mironov, Alexander I. Bulavchenko, Vladimir I. Zaikovskii, Irina V. Antonova, Alexander I. Komonov, and Maxim V. Medvedev. "Colloidal solutions of niobium trisulfide and niobium triselenide." J. Mater. Chem. C 2, no. 28 (2014): 5479–86. http://dx.doi.org/10.1039/c4tc00459k.

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45

Lubenchenko, A. V., A. A. Batrakov, I. V. Shurkaeva, A. B. Pavolotsky, S. Krause, D. A. Ivanov, and O. I. Lubenchenko. "XPS Study of Niobium and Niobium-Nitride Nanofilms." Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques 12, no. 4 (July 2018): 692–700. http://dx.doi.org/10.1134/s1027451018040134.

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46

Fabbricatore, P., G. Gemme, R. Musenich, R. Parodi, M. Viviani, B. Zhang, and V. Buscaglia. "Niobium and niobium-titanium nitrides for RF applications." IEEE Transactions on Applied Superconductivity 3, no. 1 (March 1993): 1761–64. http://dx.doi.org/10.1109/77.233593.

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47

Lubnin, Alexey N., Vladimir I. Lad`yanov, and Sergey Yu Treshchev. "Thermodynamic modeling of chemical vapour deposition of niobium coatings by reduction of niobium halides with cadmium and zinc." Himičeskaâ fizika i mezoskopiâ 26, no. 2 (2024): 219–25. http://dx.doi.org/10.62669/17270227.2024.2.19.

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Niobium is a rare, refractory metal, highly resistant to many aggressive chemical environments. The main method of deposition of niobium coatings on parts of complex shapes and internal surfaces is chemical vapor deposition (CVD) by reduction with hydrogen from higher chlorides or bromides. The disadvantage of this method is the possibility of hydrogen dissolving in the substrate with the formation of hydrides and solid solutions that deteriorate the properties. CVD of niobium from pentahalides using reducing agents stronger than hydrogen (Cd, Zn) has not been studied enough and is promising from the point of view of the increase of the intensity of the process, possibility of carrying out deposition at low temperatures, and elimination of the negative influence of hydrogen. Thermodynamic modeling of niobium deposition was carried out according to the method based on finding the entropy extremum: the software package ASTRA (author B.G. Trusov, Bauman Moscow State Technical University) was used for thermodynamic modeling of chemical and phase equilibria.The method of thermodynamic analysis shows the possibility of CVD of niobium by reducing niobium pentahalides (NbCl5, NbBr5, NbI5) with cadmium or zinc. Deposition of pure niobium coatings is possible in any of these systems except for the NbCl5-Cd system, where niobium is deposited with impurities of one or more of the following phases: NbO, Cd, CdCl2. The minimum temperatures for the niobium deposition are: 740 K in the NbI5-Zn system, 800 K in NbBr5-Zn, 840 K in NbCl5-Zn and NbI5-Cd, and 910 K in NbBr5-Cd. The regions of the thermodynamic stability of the resulting condensed phases are shown.

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48

Baranets, Sviatoslav, Hua He, and Svilen Bobev. "Niobium-bearing arsenides and germanides from elemental mixtures not involving niobium: a new twist to an old problem in solid-state synthesis." Acta Crystallographica Section C Structural Chemistry 74, no. 5 (April 20, 2018): 623–27. http://dx.doi.org/10.1107/s2053229618005739.

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Three isostructural transition-metal arsenides and germanides, namely niobium nickel arsenide, Nb0.92(1)NiAs, niobium cobalt arsenide, NbCoAs, and niobium nickel germanide, NbNiGe, were obtained as inadvertent side products of high-temperature reactions in sealed niobium containers. In addition to reporting for the very first time the structures of the title compounds, refined from single-crystal X-ray diffraction data, this article also serves as a reminder that niobium containers may not be suitable for the synthesis of ternary arsenides and germanides by traditional high-temperature reactions. Synthetic work involving alkali or alkaline-earth metals, transition or early post-transition metals, and elements from groups 14 or 15 under such conditions may yield Nb-containing products, which at times could be the major products of such reactions.

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49

Liu, Er Bao, Xiu Fang Cui, Guo Jin, Qing Fen Li, and Tian Min Shao. "Effect of Niobium Film on Corrosion Resistance of AZ91D Magnesium Alloy." Key Engineering Materials 525-526 (November 2012): 9–12. http://dx.doi.org/10.4028/www.scientific.net/kem.525-526.9.

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The niobium film is prepared by magnetron sputtering on the surface of the AZ91D magnesium alloy. The morphology, phase structure, roughness, nanohardness and elastic modulus of the niobium films were studied by filed emission scanning electron microscope, X-ray diffraction, atomic force microscope and nanoindentation respectively. The influences of film deposition parameters, such as substrate temperature, negative bias and power on the properties of films were investigated. The corrosion resistance of niobium films on magnesium alloy was investigated by electrochemical system. Results show that the microstructure, phase structure, roughness, nanohardness and elastic modulus of the niobium films are determined by power, negative bias and substrate temperature. And the corrosion resistance of magnesium alloy improved obviously when coated with the niobium films.

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50

Zhuchkov, Vladimir I., Oleg V. Zayakin, and Lyudmila Yu Mikhailova. "Physicochemical properties of ternary Fe-Si-Nb and Fe-Al-Nb metallic systems." Butlerov Communications 60, no. 11 (November 30, 2019): 143–50. http://dx.doi.org/10.37952/roi-jbc-01/19-60-11-143.

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The Russian Federation has a sufficient number of promising deposits of niobium raw materials which can satisfy the niobium and tantalum demands of Russian metallurgical enterprises for many decades. Ferroalloy technologists are faced with the difficult tasks of developing from various types of ore raw materials not only effective processes for its processing but also new acceptable rational compositions of niobium-containing ferroalloys. The chemical composition of niobium ferroalloy should, on the one hand, correspond to the product obtained by benefication (concentrate) and, on the other hand, satisfy the requirements of steelmakers for ferroalloys intended for microalloying niobium steel. To develop rational compositions of new niobium-containing ferroalloys in this work the physicochemical characteristics (which include crystallization temperature and density) of alloys containing 10-50% Nb, 10-40% Si, and 5-30% Al were studied. Two-component Fe-Nb metal alloys have a rational crystallization onset temperature (<1400 °С) only when the niobium content is not more than 10%. To achieve rational crystallization onset temperatures it is necessary to use complex alloys with silicon and aluminum. Studies have shown that a decrease in the crystallization onset temperature of complex niobium alloys occurs when the niobium content decreases with an increase in the concentration of silicon or aluminum. Three-component alloys Fe-Si-Nb and Fe-Al-Nb with a content of 15-20% Nb, 32-40 Si% or 12-30% Al belong to the category of low-melting ferroalloys. To achieve rational density values light metals such as silicon or aluminum must be introduced into a two-component system. The studied three-component alloys with a content of 25-40% Si or 15-30% Al have rational density values both from the point of view of their production and application to the processing of steel melt. The best physicochemical characteristics providing high service properties are possessed by complex niobium (15-20% Nb) FeNbSi alloys with 32-40% Si and FeNbAl with 15-30% Al which are recommended for widespread use in ladle microalloying of steels.

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Journal articles on the topic 'Niobium'

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