The tantalum carbides, niobium carbides, and tantalum niobium carbides from H.C. Starck Tungsten Powders have an especially narrow grain-size distribution and an …Web
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Niobium and tantalum mineral deposits are most com-monly associated with igneous rocks3, including granites, pegmatites4, syenites5 and carbonatites6. Some secondary ... 5 Syenites: coarse-grained igneous rocks that are composed largely of the potassium- and/or sodium-rich mineral alkali feldspar.Web
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Geological Information Center lists about 20 tin-tungsten greisen, stockwork and quartz vein-type deposits and more than 160 occurrences and placers distributed in …Web
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Pegmatites are coarse-grained (most crystals >1 cm) igneous intrusive rocks found in a variety of tectonic and metamorphic settings. They form small (usually less than a metre thick and tens to hundreds of metres long) sills, dikes, and irregular pods and lenses (Jahns, 1955; Varlamoff, 1972; Černý, 1975, 1982).Web
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Niobium and tantalum are two rare metals that have similar physical and chemical properties and occur together in nature. They are considered to be strategic and critical materials for the economy and national security of many industrial countries. Both elements are on the 2022 List of Critical Minerals of the USA as well as on the European …Web
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The second type of scrap represents the oxidized tantalum and fine-grained unoxidized tantalum scrap. The last one has to be oxidized by roasting, before treating with nitric or hydrochloric acid. ... Fluorination of tantalum or niobium oxides in the presence of oxides of other metals yields complex fluoride compounds, containing both tantalum ...Web
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A high-purity coarse-grained tantalum ingot was obtained by means of double electron-beam melting. Interstitial (O<65, N<5, wt.-ppm) and metallic (W<55, Fe<45, Al<30 and Si<50, wt.-ppm) impurity contents are in agreement with ASTM-B-364-92. ... A coarse-grained niobium plate was cut out from the longitudinal section of an electron …Web
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It was recently shown that niobium–alumina aggregates can be produced via alginate gelation, [ 7] castable technology, [ 8, 9] or extrusion. [ 10] Such aggregates …Web
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Laser scanning and SEM micrographs in Fig. 1 show the differences of the used raw powders tantalum, Alodur and CT9FG. Ta shows coarse particles with round edges and also a fine-grained fraction in the raw powder. Alodur also shows coarse particles but compared to Ta the particles edges are sharper and no fine-grained fraction …Web
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The received fine- and coarse-grained composites were evaluated regarding geometrical density and linear shrinkage. The bulk density and open porosity were measured using the Archimedes principle according to the DIN EN 993-1:2019-03. Table 1. Properties of raw material and fine-grained powder mixture recipe. Raw material …Web
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Niobium- and tantalum-bearing pegmatites that have experienced hydrothermal alteration commonly demonstrate evidence of niobium and tantalum mobilization. For example, fine-grained secondary muscovite containing ∼50 ppm Ta and ∼25 ppm Nb in the Tanco pegmatite is interpreted to have crystallized from Ta-bearing …Web
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Rare metals such as tantalum, niobium, lithium, and rubidium have been widely used in national economy applications and many high-tech fields due to their special physical and chemical properties [1,2].Tantalum and niobium are employed in electronic industry, special alloys, atomic energy, chemical, and other high technology industries …Web
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FIELD: mining. SUBSTANCE: enrichment of tantalum-niobium ores by a gravitational and magnetic method comprises crushing of initial ore with the delivery of the crushed material for preliminary sizing with the separation of a coarse-grained fraction and fine-grained fraction, ready to processing, crushing in the closed cycle of the coarse-grained fraction …Web
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Fine-grained tantalum-alumina composites were studied as material for application as femoral head in total hip arthroplasty [23]. Download : Download high-res image (144KB) Download : Download full-size image; Fig. 1. Values of the volumetric thermal expansion coefficient of niobium, tantalum and alumina as given by Kirby [3].Web
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Crystal structure Body centred Body centred Niobium is a shiny, ductile metal with a white lustre. Nat- cubic cubic urally-occurring niobium consists almost exclusively of the Table 1 Selected properties of niobium and tantalum. isotope 93Nb; natural tantalum is mainly 181Ta, with 0.012 per cent 180Ta.Web
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Niobium is an important material for high temperature applications, in space, in superconductors or in chemical process constructions. Laser-based powder bed fusion of niobium (PBF-LB/M/Nb) offers new opportunities in design, though it is still an expensive technique. The build-up rate is an important factor for economical manufacturing using …Web
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This paper reports new quantitative experimental data on the partitioning of tantalum and niobium between aqueous 1 N NaF-KF-HF fluid and silicic aluminosilicate melt at a pressure of 1 kbar ...Web
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1 Introduction. Refractory metal (molybdenum, niobium, and tantalum) matrix composite materials in combination with refractory ceramics (alumina, zirconia, …Web
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PDF | Tantalum and Niobium have been crucial in the space industry for years due to their impressive strength, corrosion resistance and other attractive... | Find, read and cite all the research ...Web
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The world's main tantalum (Ta) resources are in pegmatites (e.g. Wodgina, Australia), rare element-enriched granites (e.g. Abu Dabbab, Egypt), peralkaline complexes (e.g. Nechalacho, Canada), weathered crusts overlying the previously mentionedWeb
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The procedure was repeated through a roll setting of 1.6 mm and a 1.67-mm screen. The combined coarse mica from the three screens comprised 41% of the feed weight and contained 4.9% of the tantalum and 7.9% of the niobium. This lost tantalum and niobium was considered part of the mica lattice rather than unliberated material.Web
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The concept of coarse-grained refractory composites based on tantalum-alumina and niobium-alumina was recently introduced combining the fields of powder metallurgy and …Web
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Abstract The nanocrystalline tantalum alloys were investigated in terms of mechanical properties. The materials were obtained by powder metallurgy techniques—mechanical alloying (MA) and hot pressing (pulse plasma sintering mode). Pure powders of niobium, molybdenum, and tungsten were used for tantalum as an …Web
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Tantalum and Niobium have been crucial in the space industry for years due to their impressive strength, corrosion resistance and other attractive features. From NASA's Apollo program to SpaceX ...Web
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The strain rate and spall strength were calculated from these plots. The average spall strength for the 250 μm thick monocrystalline tantalum sample was ∼9 GPa and the average strain rate was ∼6 × 10 6 s −1. Also shown is a velocity versus time profile for the single crystal 50 μm thick tantalum.Web
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Medium- to coarse-grained porphyritic granite occurs in the middle and on the southwestern margin of the Shihuiyao mining area. The distribution and morphology of the porphyritic granite is controlled by fractured zones (Fig. 2a). ... How the low niobium/tantalum (Nb/Ta) ratios of continental crust formed is a hotly debated issue. …Web
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Tantalum usage for cemented carbides is estimated at about 240 tons per annum. Niobium usage for cemented carbides is estimated at about 60 tons per …Web
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The present study addresses the characterisation of niobium–alumina composites in terms of their fracture behaviour. Fine-grained Nb–Al2O3 composites with a niobium content of 60 vol% and produced from different alumina sources (tabular alumina or white fused alumina) were prepared by castable technique. The sintered castables …Web
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Niobium and tantalum are two rare metals that have similar physical and chemical properties and occur together in nature. They are considered to be strategic and critical materials for the economy and …Web
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The coarse-grained materials use gravity separation. The fine-grained fraction and the ore slime are combined with magnetic and gravity separation. This process is characterized by high sorting efficiency for fine-grained tantalite and niobium ore, but all tantalum and niobium minerals in the ore must have weak magnetic properties.Web
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This behavior is similar to those reported in coarse-grained aluminum [28] and coarse-grained tantalum [32]. Fig. 10 shows the orientation image maps, pole figures, and boundary misorientation ...Web
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Low grade smelter waste can be upgraded by electro thermic reduction yielding a synthetic concentrate with up to 50 per cent tantalum and niobium . Globally, it has been estimated that 10–20% of the global Tantalum supply is produced from tin slags and 20–30% from different types of manufacturing and End-of-Life scrap [ 12 ].Web
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The element niobium is a silvery metal with a low density and the chemical symbol Nb. Niobium is a lustrous, ductile metal. It is a superconductor with a high melting point. Niobium is also highly resistant to heat and corrosion, and is generally non-reactive. Niobium is a strong metal that is almost always found together with the element ...Web
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Tantalum and niobium have a strong coherence in geochemical behav- iors, and are always closely associated and freely substitute each other in the same type of mineral deposits [ 15, 16 ].Web
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A modified ECAP die by implementing the principles of indirect extrusion was fabricated to process refractory metals of Niobium and Tantalum.The main advantage of this modified technique over conventional method of ECAP is the reduction of frictional force during extrusion.Web
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Niobium and tantalum are considered critical and strategic metals based on the potential risks to their supply (because current production is restricted to only a few countries) and …Web
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Pegmatites are defined as exceptionally coarse-grained igneous. rocks (individual crystals ≥ 1 cm in size) with interlocking ... T., 1988, Niobium-tantalum mineralisation in the Motzfeldt centre ...Web
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