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Chromium Alloys, Low in Nitrogen FRED H. PERFECT Chromium metal has been produced aluminother- mically for almost a century as described by Gold- schmidt. 1,2 Some other methods by which chromium has been and is produced are, aqueous and fused salt electrolysis, the reduction of chromium chloride with
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All of the images of the raw materials are given ... However, in Experiment 7 where CaO/KCC = 0.05 and chromium reduction was high, MgO was collected at a high rate in the slag (28–36%). The formula ... The aluminothermic reduction process usually proceeds outside the furnace when the reaction temperature exceeds the melting point …
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Before heating the Si–Mo resistance furnace (i.e. before aluminothermic reduction), a vacuum pump was employed to evacuate the air in the furnace chamber, which was then refilled with pure Ar gas (99.99%) to avoid the oxidation of Al. The results of preliminary experiments showed that the aluminothermic reduction could reach …
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The processes for the production of ferroboron and ferrovanadium from indigenous resources by open aluminothermic reduction have been described. ... Diffusion of chromium in pure nickel has been ...
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An aluminothermic reaction is defined as a type of reaction where aluminum reacts with metal oxides at high temperatures, producing a large amount of heat that leads to the formation of molten metal. ... 200 mesh) and milled inside a planetary milling machine with zirconia balls. The reduction took place, and SiO x particles were synthesized ...
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In this study the viability of utilising ashes with high chromium oxide content, obtained by thermal treatment of footwear leather waste, in the production of low-carbon ferrochromium alloy (Fe-Cr ...
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Aluminothermic Combustion of Chromium Oxide Based Systems 189 Table 4. Resultsofx-raydiffractionanalysisofSHSproductsintheAl–ZrSiO4–Cr2O3 system Al,% p,atm ...
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In 1898 Hans Goldschmidt, a German chemist, produced pure chromium by the aluminothermic reduction of chromium oxide; the silicothermic process for producing low-carbon ferrochromium was developed in 1907. Chromium metal was produced by electrolysis in 1854, but this method did not find wide commercial acceptance until a …
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The previous chapter focused on the use of high-purity chromium metal for high-performance alloys in jet-engine applications. Technical emphasis in this chapter focuses on the two main variations of the electrolytic process that have traditionally produced high-purity chromium metal: the trivalent chrome-alum electrolyte method and the chromic …
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In order to accomplish extra-furnace aluminothermic reduction of activated chromium concentrate in the presence of NaCl without supply of heat, it is necessary to provide certain conditions. ... It is seen from an SEM-image (Fig. 3a) that the chromium obtained is quite finely dispersed and micro-homogeneous. According to x …
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The overall preparation steps for the exfoliation, intercalation, carbonization, and aluminothermic reaction of Si/C composite nanosheets are illustrated in Fig. 1.For comparison, two control samples were prepared: (1) the aluminothermic reaction process was omitted and EVT/C was directly etching by HCl and HF, the obtained carbon …
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production of Fe-Cr-LC employing chromium-rich leather waste ashes via non-isothermal aluminothermic reduction. The aluminothermic reduction process was patented primarily in Germany by Goldschmit, and was named the thermite reaction. Pure metals and ferro-alloys, including chromium, were commercially produced by variations of the …
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Reduction of chromium (VI) from Na 2 CrO 4 through aluminothermic reaction and fabrication of metal-ceramic materials from the reduction products have been investigated in this study. Na 2 CrO 4 could be successfully reduced into micrometer-sized Cr particles in a flowing Ar atmosphere in presence of Al powder. The conversion ratio of …
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the reduction with carbon, hydrogenor by electrolys is of a solution is not possible. Among the metals used as reducing agents are: Al,CaandMg. Figure 1 shows a schematic representation of the aluminothermic reduction, in which the particles of manganese oxide (Mn2O3) is reduced by molten aluminiumat the boundary layer.
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This work presents a two-stage aluminothermic reduction process for preparing Ti and Ti-Al alloys using Na2TiF6. Al-Ti master alloy and pure cryolite as co-products could be obtained. ... The original form picture (a) of the reduction product, and XRD patterns (b) of reduction products prepared with different ratio of Al (Al: ...
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The lowest chromium content is observed for r < 0.6 due to the incomplete reduction of chromium oxide (Figure 2(b)). The presence of the nitrogen atmosphere leads to the appearance of chromium nitrides CrN and Cr 2 N. Thus, the formation of nitrides is a specific feature of the aluminothermic system behavior in the nitrogen …
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In this work, a large ingot of micro-nano structure 2507 duplex stainless steel was prepared in a single step using the aluminothermic reaction method. Chromium having different excess fractions were added to reaction powders to make up for evaporation loss, and the results show that the composition and structure of 2507 duplex …
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Chromium borides of various phases were fabricated through combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS) by adopting the powder compacts of Cr 2 O 3 + xB (with x = 4–9) and Cr 2 O 3 + 2Al + yB (with y = 1–8). Because aluminothermic reduction of Cr 2 O 3 is more exothermic than borothermic …
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1.1. Aluminothermic Reaction. The preparation of particular multicomponent alloys containing metals with melting points of 660 °C (aluminum) as well as high-melting point-metals such as cobalt (1495 °C), titanium (1668 °C), molybdenum (2623 °C), and tungsten (3422 °C) is very difficult [1,2,3,4].Another problem with the preparation of these alloys …
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Aluminothermic reduction of chromium oxide is an exothermic autocatalytic reaction and then a potential method of recycle of chromium from oxide.
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Chrome alumina, the aluminothermic chrome metal slag, is crushed and sieved by DCX Chrome to produce grain sizes to meet customers specifications. Chrome alumina has …
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The aluminothermic reduction of some oxide systems in the solid-state combustion mode in nitrogen in a high-pressure reactor has been studied for the purpose of obtaining nitridecontaining composites. ... S.M., Alipbaev, A.N. et al. Aluminothermic combustion of chromium oxide based systems under high nitrogen pressure. …
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Aluminothermic reduction of chromium oxide is an exothermic autocatalytic reaction and then a potential method of recycle of chromium from oxide. The purpose of the present research is to investigate the kinetic process and to ind its critical temperature of this reaction.Sample pellets are prepared by mixing of aluminum powder …
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Other articles where aluminothermic process is discussed: niobium processing: Ferroniobium: …reduced to ferroniobium through an aluminothermic process. In this process, the concentrate is mixed with hematite (an iron ore), aluminum powder, and small quantities of fluorspar and lime fluxes in a rotary mixer and then unloaded into steel …
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Yoshitaka et al. reported that aluminothermic reduction of chromium oxide is an exothermic autocatalytic reaction and a potential method for recovering of chromium from its oxide [18]. ... Download: Download full-size image; Fig. 9. XRD patterns of reduction products from mixed powders including a:) non-activated (as received MoO …
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In this paper, lithium carbonate is used as a raw material, and aluminum powder is used as a reducing agent to extract metal lithium in a vacuum reduction furnace by aluminothermic reduction. The lithium recovery rate is 85% and the purity of metal lithium reaches 99.5%. In the laboratory, a continuous vacuum lithium reduction …
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The process is also being used to recover metals (Shibata et al., 2002). During the reaction, the temperature must exceed 2,100 ºC to permit the adequate separation of the product metal and slag ...
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The main stages of the formation of the Ti 3 AlC 2 in the Ti–Al–C system and the effect of the low-melting additive B 2 O 3 on the yield of the MAX phase were studied by the 13 C, 27 Al and 47,49 Ti Nuclear Magnetic Resonance (NMR) and XRD analysis. The B 2 O 3 addition reduces the synthesis temperature of the MAX phase to 1435 °C. …
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In this study, we investigated the thermodynamics and kinetics of the aluminothermic reduction of ZrO 2.The results of thermal analysis and isothermal heat treatment showed that the aluminothermic reduction of ZrO 2 was an exothermic reaction that occurred at . 958.8°C. The aluminothermic reduction process does not produce …
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In this work, a large ingot of micro-nano structure 2507 duplex stainless steel was prepared in a single step using the aluminothermic reaction method. Chromium having different excess fractions ...
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The main electrolytic method used for the production of large tonnages of chromium metal is the chromium (III) or trivalent chrome-alum bath electrolyte method. This process …
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During this process a large amount of heat is liberated, in which Cr2O3 is reduced to chromium. The molten chromium is collected in the crucible and aluminium oxide is removed as slag. Cr 2 O 3 + 2Al →2Cr + Al 2 O 3 + 468.6 kJ
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The chromium oxide is reduced by aluminum to form molten chromium and a slag of aluminum oxide is formed on its surface. Aluminothermic reduction of chromium oxide …
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tigated the aluminothermic process under nitrogen pressure for obtaining chromium nitride. It was shown that of the two reactions, Cr 2O 3+2Al fi Al 2O 3+2Cr and 4Cr+N 2 fi 2Cr 2N, the reaction of chromium oxide reduction gives the main heat release. To fabricate HNS, the reaction should proceed in the liquid state for the slag/metal separation.
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Download scientific diagram | SEM images of metallic phases obtained from aluminothermic reduction of the chromite concentrate: (a) non-activated and (b) …
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For this aim, in the experiments, the aluminothermic reduction method was applied in an open crucible. 10% CrO3 + 10% NaClO3, 15% CrO3 + 5% NaClO3 and 20% CrO3 by weight of concentrate were added ...
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