Статті в журналах: "Aluminothermic reactions"

1

Gavrilovski, Milorad, Vaso Manojlović, Željko Kamberović, Marija Korać, and Miroslav Sokić. "Semi-empirical software for the aluminothermic and carbothermic reactions." Metallurgical and Materials Engineering 20, no. 3 (September 30, 2014): 199–206. http://dx.doi.org/10.5937/metmateng1403199g.

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Understanding the reaction thermochemistry as well as formatting the empirical data about element distribution in gas-metal-slag phases is essential for creating a good model for aluminothermic and carbothermic reaction. In this paper modeling of material and energy balance of these reactions is described with the algorithm. The software, based on this model is basically made for production of high purity ferro alloys through aluminothermic process and then extended for some carbothermic process. Model validation is demonstrated with production of FeTi, FeW, FeB and FeMo in aluminothermic and reduction of mill scale, pyrite cinders and magnetite fines in carbothermic process.

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2

Hassan-Pour, S., C. Vonderstein, M. Achimovičová, V. Vogt, E. Gock, and B. Friedrich. "Aluminothermic production of titanium alloys (Part 2): Impact of activated rutile on process sustainability." Metallurgical and Materials Engineering 21, no. 2 (June 30, 2015): 101–14. http://dx.doi.org/10.30544/100.

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The aluminothermic process provides a cost-reduced production method for titanium and titanium alloys by reduction of TiO2 with subsequent refining by electroslag remelting The aluminothermy involves high heating rates, high temperatures and short reactions times combined with a self-propagating behaviour of the reaction. By co-reduction of TiO2 and oxides of alloying elements such as vanadium pentoxide, direct synthesis of a titanium alloy is possible. The use of rutile ore concentrates causes a further reduction of process steps. In order to charge rutile ore complex thermodynamic calculations are required taking enthalpy input of various bycomponents into account. The aluminothermic reduction is conventionally enhanced by a highly heatproviding reaction based on the reduction of KClO4. In order to minimize the use of chlorine-based products extensive studies are made to investigate the feasibility of using mechanically activated rutile as input material for the aluminothermic process. Due to the mechanical activation the intrinsic enthalpy of the reaction is increased thus facilitates a process with reduced amount of KClO4. A major challenge represents the determination of a compromise between low activation duration and reduced KClO4 amount. In order to define the process window parameters like intrinsic chemical energy (enthalpy of the reaction mixture), equilibrium temperature and physical properties (particle size and mixing degree) were optimized. After adjusting the process parameters it is possible to save up to 42 % KClO4 for the ATR reaction with 2h activated input material. This reduction of KClO4 material affects a decrease of the produced gaseous compounds and the subsequent off-gas cleaning system.

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3

Silyakov, S. L., V. N. Sanin, and V. I. Yukhvid. "Aluminothermic SHS reactions: effect of scaling." International Journal of Self-Propagating High-Temperature Synthesis 20, no. 3 (September 2011): 176–80. http://dx.doi.org/10.3103/s1061386211030125.

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4

Branzei, Mihai, Mihai Ovidiu Cojocaru, Tudor Adrian Coman, and Ovidiu Vascan. "A Model of Optimization and Control the Thermite Kit for Aluminothermic Welding." Solid State Phenomena 254 (August 2016): 83–90. http://dx.doi.org/10.4028/www.scientific.net/ssp.254.83.

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Thermite welding (TW) is now widely used all over the world to weld, maintenance and modernization railway and tram rails [1]. The main materials from the thermite composition (TC), results from manufacturing scraps, which can be retrieved all over the country. Exothermic welding (EW) which is based on the exothermal reaction between iron oxides (FeO, Fe2O3 and Fe3O4) and aluminium powder, takes place at temperatures up to 3500 °C and during casting rail ends are melted in order to be welded.In was studied the thermal effects of the aluminothermic reduction reactions of the iron oxides, which were dosed in different percentages. The aluminothermic reaction efficiency is given by strictness in the ratio of the TC selection and mainly in the iron oxides types. Their correct dosage makes possible the control the exothermic reaction (ER) effect. Also it is revealed the effect of particle size from thermite powder (TP) on the thermite dynamics reactions. Is also presented a model of optimization and control the thermite kits (TK) for aluminothermic welding (AW). Finally, the TK composition can be calculated from "QUARK1" Diagram, as function of the heat amount necessary for the welding.

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5

Lad’yanov, V. I., G. A. Dorofeev, E. V. Kuz’minykh, V. A. Karev, and A. N. Lubnin. "ALUMINOBAROTHERMIC SYNTHESIS OF HIGH-NITROGEN STEEL." Izvestiya. Ferrous Metallurgy 62, no. 2 (March 30, 2019): 154–62. http://dx.doi.org/10.17073/0368-0797-2019-2-154-162.

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High-nitrogen austenitic steels are promising materials, combining high strength, plasticity and corrosion resistance properties. However, to produce high-nitrogen steel by conventional metallurgical methods under high nitrogen pressure, powerful and complex metallurgical equipment is required. From energy-saving viewpoint, an alternative and simpler method for producing high-nitrogen steels can be aluminothermy (reduction of metal oxides by metallic aluminum) under nitrogen pressure. Thermodynamic modeling of aluminothermic reactions in a nitrogen atmosphere was carried out by the authors. Aluminothermy under nitrogen pressure was used to produce high-nitrogen nickel-free Cr – N and Cr – Mn – N stainless steels with a nitrogen content of about 1 %. Microstructure (X-ray diffraction, metallography and transmission electron microscopy techniques) and mechanical properties were examined. Thermodynamic analysis has shown that the aluminothermic reduction reactions do not go to the end. The most important parameter of the synthesis is the ratio of Al and oxygen in the charge, the correct choice of which provides a compromise between completeness of oxides reduction, content of aluminum and oxygen in steel (the degree of deoxidation), and its contamination with aluminum nitride. Cr – N steel ingots in the cast state had the structure of nitrogen perlite (ferrite-nitride mixture), and Cr – Mn – N steel – ferrite-austenite structure with attributes of austenite discontinuous decomposition with Cr2 N precipitations. Quenching resulted in complete austenization of both steels. The compliance of the austenite lattice parameter obtained from the diffractograms for quenched Cr – Mn – N steel with the parameter predicted from the known concentration dependence for Cr – Mn – N austenitic steels indicated that all alloying elements (including nitrogen) were dissolved in austenite during aging at quenching temperature and fixed in the solid solution by quenching. Study of the mechanical properties of quenched Cr – Mn – N steel has shown a combination of high strength and ductility. It is concluded that by the aluminothermic method a high-nitrogen steel can be obtained, which, by mechanical properties, is not inferior to industrial steel – analog manufacted by electroslag remelting under nitrogen pressure.

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6

Xu, Kaiqi, Zhizhen Zhang, Wei Su, Zengfu Wei, Guobin Zhong, Chao Wang, and Xuejie Huang. "Alumina coated nano silicon synthesized by aluminothermic reduction as anodes for lithium ion batteries." Functional Materials Letters 10, no. 02 (April 2017): 1650073. http://dx.doi.org/10.1142/s1793604716500739.

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Alumina (Al2O[Formula: see text] coated nano silicon was synthesized by aluminothermic reduction for the first time. It was realized by preoxidation of the nano silicon followed by a aluminothermic reduction that transformed the surface silicon oxide into Al2O3. The thickness of Al2O3 can be controlled by regulating the preoxidized temperature and the processing time. The nano silicon coated with 2–4[Formula: see text]nm Al2O3 showed a more stable cycling performance and a higher coulombic efficiency than the uncoated nano silicon. It is believed that the improved electrochemical performance was benefited from the Al2O3 coating, which could hinder the side chemical reactions during the cycling process. This work provides an alternative method for surface coating on nanomaterials by safe and flexible solid state chemical reaction.

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7

Gulyaeva, R. I., A. M. Klyushnikov, S. A. Petrova, and L. Yu Udoeva. "Kinetics of low-temperature aluminothermic reduction of iron tantalate." Perspektivnye Materialy 6 (2021): 60–72. http://dx.doi.org/10.30791/1028-978x-2021-6-60-72.

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The kinetics of low-temperature (900 – 1180 °C) reduction of iron tantalate (98.2 wt % FeTa2O6, 1.8 wt % Ta2O5, particle size < 0.1 mm) by excess aluminum (particle size < 0.14 mm) at the molar ratio Al:FeTa2O6 = 6 was studied. According to differential scanning calorimetry and X-ray powder diffraction, reduction is almost completed at 1180 °C, the metal products are TaFeAl, TaAl3, and Ta17Al12. Based on the results of thermokinetic calculations (Ozawa – Flynn – Wall and nonlinear regression methods), the formal mechanism of the process is represented by the Bna → CnC model, which includes two consecutive steps controlled by autocatalytically activated reactions. Kinetic parameters of the steps are: 1) Е1 = 429 kJ·mol–1, A1 = 1015.3 s–1; 2) Е2 = 176 kJ·mol–1, A2 = 103.9 s–1 (Ej is the activation energy, Aj is the preexponential factor). Prediction in the Bna → CnC model frames indicates the possibility of obtaining a reaction mixture containing ≥ 98 mol. % the final formal reduction product, with isothermal exposure in the temperature range of 1040 – 1120 °C during 1.5 – 5 minutes. The proposed model can be used to develop scientific foundations and substantiate technological modes for obtaining tantalum alloys from mineral and technogenic raw materials.

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8

Cao, Giacomo, Giorgio Concas, Anna Corrias, Roberto Orru', Giorgio Paschina, Barbara Simoncini, and Giorgio Spano. "Investigation of the Reaction between Fe2O3 and Al Accomplished by Ball Milling and Self-Propagating High-Temperature Techniques." Zeitschrift für Naturforschung A 52, no. 6-7 (July 1, 1997): 539–49. http://dx.doi.org/10.1515/zna-1997-6-713.

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Abstract In this work we investigate the mechanism of product formation of the aluminothermic reaction of Fe2O3 in the presence of Al2O3 using Ball Milling and Self-propagating High-temperature techniques. Results obtained by experiments under either argon or air atmosphere are analysed by X-ray diffraction and Mössbauer spectroscopy, together with microstructure observations. It is shown that ball milling products are strongly affected by the kind of atmosphere, while self-propagating high-temperature ones are only weakly influenced. Reaction mechanisms taking place in these cases are proposed. While ball milling involves only solid state reactions, the formation of a melt occurs under self-propagating high-temperature conditions.

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9

Golmakani, M. H., Vahdati Khaki, and A. Babakhani. "Formation mechanism of Fe-Mo master alloy by aluminothermic reduction of MoS2-Fe2O3 in the presence of lime." Journal of Mining and Metallurgy, Section B: Metallurgy 54, no. 2 (2018): 233–41. http://dx.doi.org/10.2298/jmmb180316011g.

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The reaction mechanism of MoS2-Fe2O3 aluminothermic reduction in the presence of lime using microwave-assisted combustion synthesis method was surveyed. Achieving technical feasibility in one-step production of ferromolybdenum along with sulfur removing in solid form are the main features of this novel process. Simultaneous Preliminary thermoanalytical investigations DSC/TGA and X-ray diffraction experiments during the heating process of 0.42MoS2 +1.14Al + 0.29Fe2O3 +0.84CaO demonstrated four key sequential endothermic and exothermic reactions at 420, 540, 660, and 810?C. The most noteworthy reactions involve evaporation of moisture and volatile matter, molybdenite roasting, simultaneous production of lateral compounds such as CaMoO4 and CaSO4, aluminum melting transition, and final termite reaction. Kinetics procedure of the system was conducted using a classical model-free approach by Kissinger?Akahira?Sunose (KAS) method. In this study, the activation energy was determined about 106.4 (kJ.mol-1) for thermite reaction in the temperature range of 810 to 918?C.

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10

Li, Xue Feng, Yu Qin Liu, Hui Li, Yun Jiang, and Hong Wen Ma. "Effects of Briquette Forming Condition on the Extraction of Magnesium from Calcined Magnesite via Vacuum Aluminothermic Reduction." Materials Science Forum 849 (March 2016): 168–72. http://dx.doi.org/10.4028/www.scientific.net/msf.849.168.

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Vacuum aluminothermic reduction of magnesia is multi-phase chemical reaction and the briquette forming condition has a great influence on the extent of the reactions. This paper focused on the effect of briquette forming condition on the extraction of magnesium from calcined magnesite. Briquettes were prepared at different conditions, including two forming pressures, four briquette thicknesses and two briquette diameters. The reduction ratio was calculated from the weight loss of the briquette before and after thermal reduction. The obtained condensed magnesium and briquette residues were mainly characterized via X-ray diffraction analysis and scanning electron microscopy. It was revealed that the briquette preparation condition had a great influence on the reduction ratio of magnesia and the phase constitution of the briquette residues, but had a minor influence on the morphology of condensed magnesium.

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11

Kudyba, Artur, Shahid Akhtar, Inge Johansen, and Jafar Safarian. "Aluminothermic Reduction of Manganese Oxide from Selected MnO-Containing Slags." Materials 14, no. 2 (January 13, 2021): 356. http://dx.doi.org/10.3390/ma14020356.

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The aluminothermic reduction process of manganese oxide from different slags by aluminum was investigated using pure Al and two types of industrial Al dross. Two types of MnO-containing slags were used: a synthetic highly pure CaO-MnO slag and an industrial high carbon ferromanganese slag. Mixtures of Al and slag with more Al than the stoichiometry were heated and interacted in an induction furnace up to 1873 K, yielding molten metal and slag products. The characterization of the produced metal and slag phases indicated that the complete reduction of MnO occurs via the aluminothermic process. Moreover, as the Al content in the charge was high, it also completely reduced SiO2 in the industrial ferromanganese slag. A small mass transport of Ca and Mg into the metal phase was also observed, which was shown to be affected by the slag chemistry. The obtained results indicated that the valorization of both Al dross and FeMn slag in a single process for the production of Mn, Mn-Al, and Mn-Al-Si alloys is possible. Moreover, the energy balance for the process indicated that the energy consumption of the process to produce Mn-Al alloys via the proposed process is insignificant due to the highly exothermic reactions at high temperatures.

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12

Beltran, Cesar, Alfredo Valdes, Jesús Torres, and Rocio Palacios. "A Kinetic Study on the Preparation of AlNi Alloys by Aluminothermic Reduction of NiO Powders." Metals 8, no. 9 (August 28, 2018): 675. http://dx.doi.org/10.3390/met8090675.

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In this work, the experimental results obtained during the preparation of Al-Ni and Al-Ni-Mg alloys using the aluminothermic reduction of NiO by submerged powder injection, assisted with mechanical agitation are presented and discussed. The analyzed variables were melt temperature, agitation speed, and initial magnesium concentration in the molten alloy. For some of the experiments performed, it was found that the Ni concentration increased from 0 to about 3 wt-% after 90 min of treatment at constant temperature and constant agitation speed. In order to determine the values of the kinetic parameters of interest, such as the activation energy and the rate constants, the values of the results obtained were fitted to the kinetic formulae available. Moreover, the kinetics of the reaction were found to be governed by the diffusion of Al and Mg to the NiO boundary layer, where MgAl2O4 or Al2O3 were formed as the main reaction products. Finally, from a thermodynamic study of the system, the main reactions that took place are explained.

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13

Russkih, Andrey S., Sergey N. Agafonov, and Artem A. Ponomarenko. "Joint aluminothermic reduction of oxides Zr, Ta and Nb." Butlerov Communications 60, no. 11 (November 30, 2019): 11–15. http://dx.doi.org/10.37952/roi-jbc-01/19-60-11-11.

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Alloys based on the Al-Zr system with insignificant Ta and Nb additives are in demand in the synthesis of complex alloys used to produce titanium alloys for aircraft and rocket technology. A common method for producing aluminum-zirconium alloys and ligatures is the out-of-furnace metallothermal reduction of zirconium from oxides and direct fusion of components. The practice of such methods has a number of significant disadvantages: poor separation of the metal and oxide phases, a low degree of extraction of the target component, the use of thermal additives, and the high cost of the resulting product. The solution to the problem may be a technology option where the temperature regime of the metallothermal reduction process is ensured both due to the heat of exothermic reactions and due to the additional supply of relatively inexpensive electrical energy. In this work, we investigated the possibility of obtaining alloys using metallothermal reduction from oxides based on ZrAl with Ta and Nb additives. An experimental technique for producing an alloy is presented. The data of X-ray phase analysis (XRD) and chemical analysis of the alloy. as well as an analysis of the content of oxygen and nitrogen in the alloy. X-ray phase analysis showed the formation of the ZrAl2 compound in all the studied alloys, as well as solid solutions (Zr4Nb)Al3, (Zr0.8Ta0.2)Al3, (Zr4Nb0.5Ta0.5)Al3 corresponding to the added element, ZrO2 is present in the 3 alloys, which tells us about not up to the reduced oxide Zr. These data are confirmed by analysis of the gas content in the alloy, where there is an increased oxygen content. The performed study can serve as a scientific basis for the development of promising metallothermal technologies for the production of rare metal alloys.

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14

Yeh, C. L., and Y. C. Chen. "Fabrication of MoSi2–MgAl2O4 in situ composites by combustion synthesis involving intermetallic and aluminothermic reactions." Vacuum 167 (September 2019): 207–13. http://dx.doi.org/10.1016/j.vacuum.2019.06.014.

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15

Skidin, Ihor, Oksana Vodennikova, Sergii Vodennikov, Levan Saithareiev, and Shamil Telkov. "Parameter analysis of non-metallic inclusion formation in thermite alloys." E3S Web of Conferences 280 (2021): 07015. http://dx.doi.org/10.1051/e3sconf/202128007015.

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The methodology of calculating parameters of the primary and secondary non-metallic inclusion formation in thermite alloys is offered. The regularities of the growth time of non-metallic inclusion in the form of corundum depending on its size, mass and quantity are analysed. It is shown that in the thermite alloy obtained by self-propagating high-temperature synthesis, the average size of corundum inclusions, surrounding the heterogeneous inclusions of chromium carbide, is 15.4 μm. It is shown that during the process of aluminothermic reactions of the SHS process a significant number of small inclusions of corundum is formed. It is shown that the alumina particles are dissolved in the alloy and they are the centers of crystallization and play the role of inoculating modifier.

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16

Dyzia, Maciej. "Fine Particle Reinforced Composites Obtained by Suspension Method." Solid State Phenomena 211 (November 2013): 53–56. http://dx.doi.org/10.4028/www.scientific.net/ssp.211.53.

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In the production of composites by the suspension method (mechanical stirring) may beused, ceramic particles, which are wetted by the liquid metal such SiC, Al2O3or glassy carbon.However, to obtain a stable suspension with the use a particle size below 10 μm is extremelydifficult. Phenomena related i.a. with agglomeration of particles, convection currents over moltenmetal surface make practically impossible to obtain composite material. One possibility to obtainfine reinforced composite is the use of in situ methods, in which the reinforcing phase is formed bythe reaction between the aluminum and the reactive powder oxides such FeO, TiO2, SiO2, NiO, Nb2O5or Fe2O3. Such reactions are exothermic (aluminothermic) and their kinetics dependent onthe dispersion of the reactants, the quantitative phase composition and temperature.The technological solution involving the formation of a suspension with particles (chemically activewith aluminum) is one of the promising solutions to obtain batch material for the synthesis ofcomposites reinforced with Al2O3and intermetallic phases. The aim of this study is to evaluate thesuitability of suspension technology to obtained in situ fine reinforced composite.

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17

Yeh, C. L., and Y. S. Chen. "Effects of Al content on formation of TaC, Ta2C, and Ta2AlC by combustion synthesis with aluminothermic reactions." Ceramics International 43, no. 17 (December 2017): 15659–65. http://dx.doi.org/10.1016/j.ceramint.2017.08.124.

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18

Ksandopulo, G. I., A. N. Baideldinova, K. I. Omarova, and A. M. Ainabayev. "Initiating Potential of Centrifugally Accelerated Metal Particles in the Inorganic Synthesis Reactions." Eurasian Chemico-Technological Journal 16, no. 1 (December 22, 2013): 49. http://dx.doi.org/10.18321/ectj168.

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The method of producing clusters of various metals by using self-propagating high-temperature synthesis (SHS) in the conditions of high-speed rotation is presented. The purpose of a study is development of the technology of the acceleration of strong- endothermic reactions and synthesis of ceramic materials and products. The task of a experimental study consists of the observation of the wave of combustion in the effective layer, the determination of the coordinate of its passage in the adiabatic regime and the arrangement here of less effective layer for the purpose of obtaining gradient and composite materials. The possibility of the output of the process of the combustion of oxide system to the adiabatic regime is shown. The limits of inflammability in the centrifugal-force field come down by the attack of the adiabatic wave of combustion by accelerating the front of combustion with the molten particles of metal, returned into the zone of reaction by centrifugal acceleration. The potential possibility of using the centrifugal efforts for the production of ceramic materials was demonstrated for the multilayer aluminothermic systems. The speed of motion of metal particles under the influence of centrifugal acceleration is calculated. In the reactor of 30 cm long the speed of particles of tungsten reaches 94 m/s with a frequency of rotation of 3 000 rev/min received accelerated clusters of metals that are considered as possible sources of initiation of the chemical processes having about MJ/mol of activation energy. This method was allowed to produce gradient materials.

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19

Nie, Jian Hua, Ya Wei Li, Hao Yan, Yong He Liang, and Yuan Bing Li. "TiN/Al₂O₃ Composite Material Synthesized by Aluminothermic Reduction Process in Reductive Atmosphere." Key Engineering Materials 368-372 (February 2008): 721–23. http://dx.doi.org/10.4028/www.scientific.net/kem.368-372.721.

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TiN/Al2O3 composite material was prepared by aluminothermic reduction of TiO2 in coke bed from mixtures of TiO2 powder and metal Al powder. The phase composition, lattice parameter and microstructure of products after treatment in different temperatures were analyzed by XRD, SEM. The results show that TiN/Al2O3 composite material can be produced in coke bed via aluminothermic reduction reaction. Moreover, the treatment temperature affects the evolution of aluminothermic reaction and morphology of products obviously. The content, grain size and lattice parameter of TiN in products in coke bed increase with the increasing of treatment temperature. Thermodynamically it confirms that metal Al reacts with oxygen in coke bed while it is involved in aluminothermic reduction reaction, and then it causes the lack of Al, which takes part in the aluminothermic reaction leading to a surplus rutile in the products.

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20

Maderthaner, Magdalena, Alexander Jarosik, Gerhard Angeli, and Roland Haubner. "3^rd Generation Hot-Dip Galvanized Steel Sheet for Automobile Manufacturing - Interface Reactions between Zinc and Metal Oxide." Key Engineering Materials 742 (July 2017): 463–70. http://dx.doi.org/10.4028/www.scientific.net/kem.742.463.

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There is a growing demand for Advanced High Strength Steels (AHSS) in the automotive industry owing to their high specific strength and good formability. The mechanical properties satisfy the demands for improved passenger safety and decreased vehicle weight due to thinner cross sections. Hot-dip galvanizing is a common procedure to prevent corrosion of steel, galvanized steel forms the basis for further processing like organic coating. Industrially, the steel strip is annealed at 840 °C in 5 % H2 in N2 at a dew point (DP) of -30 °C. These conditions are reducing for Fe, but oxidizing for oxygen-affine alloying elements as Mn, Si and Cr. These ignoble elements form an external, covering oxide layer on the steel surface, which exhibits poor wettability for the Zn(Al, Fe)-bath. The liquid Zn(Al, Fe) has a temperature of 460 °C and contains 0,2 wt% Al to form a Fe2Al5-xZnx-layer to inhibit the growth of Fe-Zn-intermetallics. Along with the increased amount of alloying elements to improve strength and ductility of AHSS the evolving oxide layer after annealing at the steel surface deteriorates hot-dip galvanizing. The question arises what happens to the surface oxides during immersion in the Zn(Fe, Al)-bath. For this purpose annealed as well as annealed and galvanized 0.8Si-AHSS and 1.5Si-AHSS were compared by glow discharge optical emission spectroscopy (GD-OES) depth profiles. Galvanized specimens show fewer oxides at the steel-zinc-interface as annealed specimens. A possible explanation is an aluminothermic reduction of oxides by 0.2 wt% dissolved Al in the Zn(Al, Fe)-bath. Al is thermodynamically more affine to oxygen than Mn and Si and may reduce Mn- and Si-oxides. An alternative theory is the dissolution of Fe in Zn during reactive wetting, as a side effect the oxides are rinsed off too. Additionally, the influence of DP was investigated. According to Wagner’s theory of selective oxidation, a higher amount of oxygen in the annealing atmosphere leads to internal oxidation of the alloying elements. Experiments were carried out with 0.8Si-AHSS and 1.5Si-AHSS by altering the DP during annealing from -30 °C (380 ppm H2O) to 0 °C (6000 ppm H2O). Oxidation mode changed from external (DP -30 °C) to internal oxidation along grain boundaries (DP 0 °C), as predicted by Wagner. These oxide-free surface provides good reactivity to enhance reactive wetting with the Zn(Fe, Al)-bath and form a dense Fe2Al5-xZnx-layer.

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21

Sheybani, K., M. H. Paydar, M. H. Shariat, and N. Setoudeh. "An investigation on aluminothermic reduction of MoO3 in domestic microwave oven." Journal of Mining and Metallurgy, Section B: Metallurgy, no. 00 (2020): 25. http://dx.doi.org/10.2298/jmmb190312025s.

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In the present study, feasibility of aluminothermic reduction of molybdenum oxide by microwave oven was studied. Furthermore, the effect of compaction pressure, the amount of used Al and CaO, as flux on aluminothermic reduction of molybdenum oxide were investigated. Thermodynamic analysis of the corresponding reaction indicated that, aluminothermic reduction of MoO3 is possible at all temperatures. XRD patterns and thermodynamic investigation of reaction products indicated that aluminothermic reduction of molybdenum oxide progressed through the formation of intermediate phases such as Al2 (MoO4)3 and MoO2, where the final products were elemental Mo and Al2O3. Results revealed that by increasing the compaction pressure of the pellet, undesired phases of molybdenum dioxide (MoO2) and aluminum molybdate Al2(MoO4)3 can be detected among the final products. By increasing the amount of Al more than stoichiometric ratio, the intermediate phases such as MoO2 is produced. The results indicated that by adding CaO to the MoO3-Al system, the unwanted molybdenum dioxide (MoO2) and aluminum molybdate (Al2 (MoO4)3) compounds were successfully reduced to Mo. In the present work, metallic molybdenum could easily and successfully be separated from Al2O3 slag, as the side product of the reaction, in molten phase, based on the difference in their densities.

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22

Wang, Hai Bo, Xi Bao Wang, and Hui Li. "A Comparative Study of SHS Synthesis of TiB₂ Cermets Powder by Magnesium Reduction and Aluminothermy Reduction." Advanced Materials Research 567 (September 2012): 33–36. http://dx.doi.org/10.4028/www.scientific.net/amr.567.33.

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In this paper, metal reduction preparation of TiB2 powder via magnesium reduction and aluminothermic reduction were studied. The carbon rod arc heating generated from the spread of the reaction of TiB2，and then the examinations were performed after pickling, crushing and grinding such as SEM and XRD. The results showed that the aluminothermic reduction occurred into the powder impurity phase less, but the need for better technology separation of Al2O3. Magnesium reduction reaction products with more impurities, pickling process removes only the reactants of MgO and other impurities not removed in the air and impurities were analyzed and compared.

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23

Wang, Y. W., J. You, A. G. Wang, J. P. Peng, and Y. Z. Di. "Production of Mg-Li alloys by aluminothermic vacuum reduction." Journal of Mining and Metallurgy, Section B: Metallurgy 56, no. 1 (2020): 43–49. http://dx.doi.org/10.2298/jmmb190419053w.

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Анотація:

Mg?Li alloys are the lightest metallic construction materials and one of the most representative light alloys. The process of producing Mg?Li alloys by vacuum aluminothermic reduction, using magnesite and lithium carbonate as raw materials, was studied. The influence of reduction parameters on the extents of reduction of MgO and Li2O was investigated. The results show that Mg?Li alloys can be produced by vacuum aluminothermic reduction using calcined magnesite and lithium carbonate. MgO was relatively easier to reduce by aluminum than Li2O. Almost all MgO was reduced to Mg and more than 96% of Li2O was reduced to Li. The main phase in the reduction slag was Li2O?5Al2O3. The reaction mechanism was discussed. Vacuum aluminothermic reduction can be considered as a highly efficient and environmental friendly method for producing Mg?Li alloys.

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24

Michna, Štefan, Anna Knaislová, Iryna Hren, Jan Novotný, Lenka Michnová, and Jaroslava Svobodová. "Chemical and Structural Analysis of Newly Prepared Co-W-Al Alloy by Aluminothermic Reaction." Materials 15, no. 2 (January 16, 2022): 658. http://dx.doi.org/10.3390/ma15020658.

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Анотація:

This article is devoted to the characterization of a new Co-W-Al alloy prepared by an aluminothermic reaction. This alloy is used for the subsequent preparation of a special composite nanopowder and for the surface coating of aluminum, magnesium, or iron alloys. Due to the very high temperature (2000 °C–3000 °C) required for the reaction, thermite was added to the mixture. Pulverized coal was also added in order to obtain the appropriate metal carbides (Co, W, Ti), which increase hardness, resistance to abrasion, and the corrosion of the coating and have good high temperature properties. The phase composition of the alloy prepared by the aluminothermic reaction showed mainly cobalt, tungsten, and aluminum, as well as small amounts of iron, titanium, and calcium. No carbon was identified using this method. The microstructure of this alloy is characterized by a cobalt matrix with smaller regular and irregular carbide particles doped by aluminum.

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25

Student, Mykhailo, Volodymyr Hvozdetskyi, Taras Stupnytskyi, Oleksandra Student, Pavlo Maruschak, Olegas Prentkovskis, and Paulius Skačkauskas. "Mechanical Properties of Arc Coatings Sprayed with Cored Wires with Different Charge Compositions." Coatings 12, no. 7 (June 30, 2022): 925. http://dx.doi.org/10.3390/coatings12070925.

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Анотація:

The mechanical properties (hardness, cohesion, and residual stresses) of arc coatings designed for operation under conditions of boundary friction and corrosive-abrasive wear are analyzed. The coatings were formed by arc spraying cored wires (CW) with different charge compositions (the content of carbon, aluminum, and boron in CW charge varied). It is shown that the hardness of the coatings increases with an increase in the carbon content in them up to 1 wt. %, and then decreased due to an increase in the content of residual austenite in their structure. The level of residual stresses of the first kind in such coatings increased by four times with an increase in the carbon content to 2 wt. %. The hardness of the coatings and the level of residual tensile stresses in them also increase with a decrease in the aluminum content in them. In this case, the cohesive strength of the coatings increased due to the implementation of aluminothermic reactions in the droplets of the CW melt during their flight and crystallization on the sprayed surfaces. However, then, with an increase in the aluminum content in the coatings of more than 2 wt. %, their cohesive strength decreased. The level of residual tensile stresses in coatings with a high content of retained austenite decreased after heat treatment (tempering) of the specimens. Sometimes, after tempering, these stresses even transformed into residual compressive stresses (in particular, under using CW C1.4Cr14Ni2). At the same time, the tempering of specimens with a predominance of ferrite in the coating structure increased the level of residual tensile stresses in them, which is due to the precipitation of finely dispersed carbides or borides. It has been shown that the addition of boron-containing components (ferrochromium-boron, chromium-boron) to the composition of the CW charge leads to a significant increase in the hardness of the coatings. Thus, an increase in the boron content in coatings from 0 to 4 wt. % leads to an increase in their hardness from 320 HV to 1060 HV. However, this is accompanied by an increase in tensile residual stresses in the coatings and a decrease in their cohesive strength.

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26

Zhou, Hong, Shou Jun Wu, Shuang Liu, Yan Shen, Bao Shan Yang, and Xu Zheng. "Preparation of Cr₂O₃-Al₂O₃-Cr Coatings on Carbon Steel by Aluminothermic Process Based on Cr₂O₃ and Al System." Advanced Materials Research 774-776 (September 2013): 560–63. http://dx.doi.org/10.4028/www.scientific.net/amr.774-776.560.

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Анотація:

In the present work, Cr2O3-Al2O3-Cr coatings are prepared on Q235 steel by aluminothermic process based on Cr2O3Al system, using Cr2O3as diluents while a small quantity of Fe2O3to reduce reaction temperature. The results showed that after treated at 650oC for 30minutes, homogenous Cr2O3-Al2O3-Cr coatings can be prepared on Q 235 steel by aluminothermic process with the powders mixture with weight ratio of Cr2O3: Fe2O3: A1 equal to 4: 0.3: 1.12, while coatings prepared by mixture with superfluous aluminum are fragmentary. Surface hardness of the coatings prepared with superfluous Cr2O3is about 23.9GPa while that of the coatings prepared with superfluous Al is about 10.9 GPa and large scatter of 13.7% in hardness.

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27

Dyjak, S., W. Kiciński, and A. Huczko. "Thermite-driven melamine condensation to CxNyHz graphitic ternary polymers: towards an instant, large-scale synthesis of g-C3N4." Journal of Materials Chemistry A 3, no. 18 (2015): 9621–31. http://dx.doi.org/10.1039/c5ta00201j.

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Анотація:

Utilization of heat released from the classical aluminothermic reaction (Fe₂O₃ + Al) for thermal condensation of melamine allows production of a large amount of C/N/H graphitic ternary polymers within a matter of a few minutes.

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28

Gao, Fu, Ran Liu, and Xing Juan Wang. "A Preliminary Study on Preparation of MgAlON Refractory." Advanced Materials Research 750-752 (August 2013): 2191–95. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.2191.

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Анотація:

MgAlON is a new type of refractory material. This article summarized the advantages and disadvantages of the preparative technique through different methods including aluminothermic reduction, carbothermal reduction-nitridation, reaction sintering, spark plasma sintering and so on. The future development was also discussed.

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29

Kuddus, Abdul, SM Mahabubuzzaman, and Abu Bakar Md Ismail. "Investigation on the quality of silicon extracted from the Padma river sand using magnesio-aluminothermic process." Bangladesh Journal of Physics 26, no. 2 (September 20, 2020): 33–40. http://dx.doi.org/10.3329/bjphy.v26i2.49304.

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Анотація:

Investigation on the quality of the extracted Silicon (Si) from the sand of the Padma river of Bangladesh using the Magnesio-Aluminothermic process has been presented in this work. Magnesio-Aluminothermic process, which is low-energy, low-cost and CO2 free compared to conventional carbothermic process, was used for the extraction of Si from the sand. By performing the thermite process, Si was extracted as a eutectic mixture of Aluminium and Si, following that, several cycles of acid leaching were used to obtain highly pure polycrystalline silicon. After grinding the cleaned sand and making a homogeneous mixture with associated chemicals and ignition materials, modified Aluminothermic reaction was performed to produce a eutectic mixture of Si and Al. Grinded eutectic mixture of Si and Al was then purified with acid leaching and finally above 97% pure crystalline Si was extracted. XRD (X-ray diffraction) and Raman Spectroscopy confirmed the polycrystalline nature of Si where XRF (X-ray fluorescence) and EDX (Energy Dispersive X-ray Spectroscopy) corroborated the high purity of extracted Si describing the chemical composition. Bangladesh Journal of Physics, 26(2), 33-40, December 2019

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30

Liu, A., Z. Shi, K. Xie, X. Hu, B. Gao, M. Korenko, and Z. Wang. "Extraction of Al-Si master alloy and alumina from coal fly ash." Journal of Mining and Metallurgy, Section B: Metallurgy 53, no. 2 (2017): 155–62. http://dx.doi.org/10.2298/jmmb160616006l.

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Анотація:

Coal fly ash from coal power plants is a potential raw material for the production of alumina. An objective aluminothermic reduction method for the preparation of Al-Si master alloy and alumina from coal fly ash was investigated. The kinetic analysis using non-isothermal differential scanning calorimetry indicated that the reduction of Al6Si2O13, Fe2O3, and TiO2 by aluminum in coal fly ash occurs at 1618 K, 1681 K, and 1754 K, respectively. Moreover, the influence of reaction temperature on product composition was studied. The phases and morphologies of the products obtained by the aluminothermic reduction of coal fly ash at 1373-1773 K were analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy, respectively. The results from X-ray diffraction show that no oxide reduction has taken place at 1373 K and 1473K, the compositions of the product obtained by aluminothermic reduction of fly ash at 1573K- 1673 K are Al2O3, mullite, Al and Si, while the compositions of the product at 1773 K are Al2O3, Al, and Si. In addition, the chemical compositions of Al-Si alloy obtained at 1773 K are 86.81 wt% Al and 13.19 wt% Si.

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31

Mendes, Marcio W. D., António Carlos P. Santos, Francisca de Fatima P. Medeiros, Clodomiro Alves Jr., A. G. P. Silva, and Uilame Umbelino Gomes. "Aluminothermic Reduction of Niobium Pentoxide in a Hydrogen Plasma Furnace." Materials Science Forum 514-516 (May 2006): 599–603. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.599.

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The aluminothermic reduction is a highly exothermal reaction between a metal oxide and aluminium. Conventionally this reaction is ignited by an electric resistance and the reaction products after cooling are in the form of a rigid block of mixed metal and aluminium oxide. In this work a new process of aluminothermic reduction is presented, in which the reaction is ignited by a hydrogen plasma. The niobium oxide and aluminium powders are high energy milled for six hours to form particles constituted of oxide and aluminum. Stoichiometric, substoichiometric and superstoichiometric mixtures were prepared. The mixture was placed in a stainless steel tube (the hollow cathode) inside the reactor chamber. The chamber was firstly evacuated. Then hydrogen at low pressure was introduced. In the following an electric discharge between the cathode and the anode localized just above the cathode ignites the plasma. The plasma heats the particles on the surface of the powder layer and starts the reaction that proceeds in each particle since the reactants are intimately mixed. The heat generated by the reaction propagates deeper in the layer until the whole mixture reacts. Substoichiometric mixtures can be used because hydrogen takes part of the reduction. The Nb2O5 – Al starting powder mixture and the products of the reaction are characterized by laser grain size measurement and X-Ray diffraction (XRD). The products are in form of powder or agglomerates of particles. Phases of reaction products was determined by XRD analysis and the particle size trough SEM.

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32

Sundaram, V., K. V. Logan, and R. F. Speyer. "Aluminothermic reaction path in the synthesis of a TiB2–Al2O3 composite." Journal of Materials Research 12, no. 7 (July 1997): 1681–84. http://dx.doi.org/10.1557/jmr.1997.0230.

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Анотація:

Differential thermal analysis, in air and argon, in concert with x-ray diffraction, was performed on 2- and 3-component mixtures of Al, B2O3, and TiO2, to foster an understanding of the reaction path involved in the TiB2-forming thermite reaction. In argon, aluminum reacted with B2O3 to form elemental boron, and reacted with TiO2 to form AlTi3. These two products reacted just after boron was made available at ∼1060 °C to form TiB2. Formation of Al18B4O33 by reaction between B2O3 reactant and Al2O3 product attenuated the yield of TiB2, but facilitated its formation by extraction of Al2O3 reaction barriers.

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33

Fu, Ming, S. Penumella, and J. A. Sekhar. "Micropyretic synthesis of MoSi2 powders through an aluminothermic reaction." Journal of Materials Research 14, no. 5 (May 1999): 2023–28. http://dx.doi.org/10.1557/jmr.1999.0273.

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Анотація:

An aluminothermic reaction starting with inexpensive MoO3, SiO2, and Al powders was utilized to prepare molybdenum disilicide (MoSi2) powders by the micropyretic/combustion synthesis process and leaching. The combustion-synthesized product was porous and could readily be crushed into powders. X-ray diffraction (XRD) analysis revealed that the product of such a reaction consisted of α–Al2O3, MoSi2, and a small amount of Mo(Si,Al)2 and Mo5Si3. The reason for the formation of Mo(Si, Al)2 phase is discussed. MoSi2 powders were obtained by leaching out the Al2O3 from the synthesized powder mixtures in boiling phosphoric acid solution. The synthesized MoSi2 powders, including a small amount of Mo(Si, Al)2 and Mo5Si3, were very fine with an average particle size of about 1 μm.

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34

Potianikhin, Dmitrii A., and Oleg N. Komarov. "Mathematical Model of Iron Reduction with Aluminothermic Method." Advanced Materials Research 1040 (September 2014): 484–88. http://dx.doi.org/10.4028/www.scientific.net/amr.1040.484.

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Анотація:

Utilization of industrial waste in foundry engineering is one of approaches for decrease of production cost price. This technological process may be based on exothermic oxidation-reduction reaction with the resulting formation of iron from dross. Initial charge mixture consists of dispersed aluminum, iron dross and admixtures. This paper is concerned with mathematical modeling of thermite steel production. Presented model takes into account thermal, mechanical and kinetic processes occurring in aluminothermic method of steel melt production.

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35

Izumi, Marcel Tadashi, Marcio Ferreira Hupalo, Nathalie Carine Christoforo Ribeiro, Joziel de Jesus Correa, José Deodoro Trani Capochi, and Osvaldo Mitsuyuki Cintho. "Study of the Utilization of Chromium Plating Waste by Mechanical Activation." Materials Science Forum 727-728 (August 2012): 392–97. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.392.

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In this study, the production of metallic chromium via metallothermic process was investigated. A chromium oxide-rich residue from chromium plating industry was characterized. Aluminothermic reduction was performed in lab-scale using an open graphite crucible. The plating residue and the aluminum powder were processed in a SPEX mill, in order to promote its effective mixing and mechanical activation. Energy dispersive X-Ray (EDX) analyses in the scanning electron microscope (SEM) have shown the presence of metallic chromium in the reaction products.

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36

Deng, Peng, Yu Qin Liu, Da Jian Ma, and Hong Wen Ma. "Effects of Reaction Temperature and Time on the Aluminothermic Reduction of Magnesia." Advanced Materials Research 538-541 (June 2012): 2236–39. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.2236.

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Анотація:

The present paper focuses on the experimental investigation of the aluminothermic reduction of magnesia under vacuum condition with the fixed magnesia to aluminum molar ratio of 11:6. The influences of reaction temperature and time on the reduction ratio of magnesia were studied. The chemical composition, phase constitution and morphology of the condensed magnesium and the briquettes after thermal reduction were investigated by X-ray diffraction, scanning electron microscopy equipped with energy dispersive spectrometry. The reduction ratio of magnesia increases with the increase in the reaction temperature and time. The briquettes after thermal reduction at 1050°C-1150°C are mainly composed of the spinel, unreacted magnesia and aluminum. The briquette after 1 hrs thermal reduction at 1200°C contains corundum, magnesium aluminium oxide, trace amount of spinel, unreacted MgO and aluminium.

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37

Abramovici, R. "Composite ceramics in powder or sintered form obtained by aluminothermal reactions." Materials Science and Engineering 71 (May 1985): 313–20. http://dx.doi.org/10.1016/0025-5416(85)90243-5.

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38

Nie, Jian Hua, Ya Wei Li, Hao Yan, Yong He Liang, and Yuan Bing Li. "TiN/Al₂O₃ Functionally Graded Material Fabricated by In Situ Reaction." Key Engineering Materials 368-372 (February 2008): 1835–37. http://dx.doi.org/10.4028/www.scientific.net/kem.368-372.1835.

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Анотація:

TiN/Al2O3 functionally graded composite was fabricated by in-situ aluminothermic reduction of TiO2 in coke bed from mixtures of TiO2 powder and metal Al powder. The reaction process, phase composition, and microstructure of sample treated at 1500°C for 3h were analyzed by XRD, SEM and EPMA. The results indicated that the thermite reduction of TiO2 involves several transitional stages and its initial reaction temperature is lowered by prior reaction between Al and TiO2. EPMA analysis showed that the TiN/Al2O3 ratio in TiN/Al2O3 functionally graded material products changes gradually across the samples without distinct interface between the different layers. The microstructure of the composite changes gradually, and the size of TiN grains increases from the verge region of samples to the centre of samples. These results above were in agreement with thermodynamic analysis.

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39

Dávila, Orlando Flores, Jesús Torres Torres, and Alfredo Flores Valdes. "Effect of Mg Concentration on the Aluminothermic Reduction of Mn2O3 Particles Obtained from Cathodes of Discharged Alkaline Batteries: Mathematical Modeling and Experimental Results." Metals 9, no. 1 (January 7, 2019): 49. http://dx.doi.org/10.3390/met9010049.

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Анотація:

This paper aimed at studying the effect of magnesium concentration in molten aluminum produced from beverage cans on the process of aluminothermic reduction of Mn2O3 particles obtained from the cathodes of discharged alkaline batteries. The experimental results were analyzed by using thermodynamic fundamentals and kinetic modeling, while the characterization of the reaction products obtained allowed the mechanism of the process to be described. It was found that the addition of magnesium improves the wettability of solid particles by molten aluminum, thus increasing the reaction and its subsequent incorporation into the molten aluminum solution of Mn released from the reduction reaction. This work was carried out using several initial magnesium concentrations; 1.0, 2.0, 3.0, and 4.0 wt %, under a constant temperature of 1073 K, a constant treatment time of 240 min, and a constant agitation speed of 200 rpm. The results show that the higher the initial magnesium concentration in the molten alloy, the higher the speed of the chemical reduction reaction of the Mn2O3 particles.

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40

Liu, Xueyin, Ke Bao, Junfeng Chen, Quanli Jia, and Shaowei Zhang. "One-Pot Synthesis of Alumina-Titanium Diboride Composite Powder at Low Temperature." Materials 14, no. 16 (August 22, 2021): 4742. http://dx.doi.org/10.3390/ma14164742.

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Анотація:

Alumina-titanium diboride (Al2O3-TiB2) composite powders were synthesised via aluminothermic reduction of TiO2 and B2O3, mediated by a molten chloride salt (NaCl, KCl, or MgCl2). The effects of salt type, initial batch composition, and firing temperature/time on the phase formation and overall reaction extent were examined. Based on the results and equilibrium thermodynamic calculations, the mechanisms underpinning the reaction/synthesis processes were clarified. Given their evaporation losses at test temperatures, appropriately excessive amounts of Al and B2O3 are needed to complete the synthesis reaction. Following this, phase-pure Al2O3-TiB2 composite powders composed of 0.3–0.6 μm Al2O3 and 30–60 nm TiB2 particles were successfully fabricated in NaCl after 5 h at 1050 °C. By increasing the firing temperature to 1150 °C, the time required to complete the synthesis reaction could be reduced to 4 h, although the sizes of Al2O3 and TiB2 particles in the resultant phase pure composite powder increased slightly to 1–2 μm and 100–200 nm, respectively.

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41

LA, PEIQING, LI WANG, YANG ZHAO, and CHUNJIE CHEN. "EFFECT OF SUBSTRATE THICKNESS ON NANOSTRUCTURE AND MECHANICAL PROPERTIES OF BULK NANOCRYSTALLINE Fe3Al PREPARED BY ALUMINOTHERMIC REACTION." International Journal of Modern Physics B 23, no. 06n07 (March 20, 2009): 1572–77. http://dx.doi.org/10.1142/s0217979209061287.

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Анотація:

Bulk nanocrystalline Fe 3 Al materials were prepared by aluminothermic reaction on the substrates with different thickness of 5~15 mm . Grain size of the materials was measured by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Compressive strength and hardness of the materials were tested. The results showed the materials consisted of amorphous and nanocrystalline phases. With the substrate thickness increasing, amount of the nanocrystalline phase increased and that of the amorphous decreased and grain size of the nanocrystalline increased and a few grains in micrometer appeared in part areas of the materials. Yield strength and hardness of the materials remarkably decreased with the substrate thickness.

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42

Abdelrahim, H., HB Mohamed, Peiqing La, Wei Fuma, Fuling Ma, and Zhengning Li. "Effect of multiple warm rolling on microstructure and mechanical properties of 304 stainless steel prepared by aluminothermic reaction." Advances in Mechanical Engineering 12, no. 5 (May 2020): 168781401985099. http://dx.doi.org/10.1177/1687814019850998.

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Анотація:

304 stainless steels were prepared by aluminothermic reaction method; first steels are annealed at 1000°C and then rolled at 700°C for different deformation. The microstructures evolution and mechanical properties were distinguished in details. It was found that the steel contains nanocrystalline/submicrocrystalline/microcrystalline austenite and submicrocrystalline ferrite. After rolling to a thickness reduction of 30%, 50%, and 70%, the mechanical properties of the rolled steels were substantially increased, as the deformation increased from 30% to 50%, the tensile strength increased from 650 to 1110 MPa, the yield strength increased from 400 to 665 MPa, and the elongation increased from 8% to 8.5%.

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43

Sun, Ruitao, Jie Zhang, Zhilin Li, Xin Li, Huaizhi Tao, Sheng Yu, and Wenzhen Zhang. "Research on temperature propagation law based on thermite plugging and abandonment technology." E3S Web of Conferences 352 (2022): 01066. http://dx.doi.org/10.1051/e3sconf/202235201066.

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The continuous exploration and development of oil wells increases the risk of leakage from abandoned wells and brings challenges to the traditional plugging and abandonment technology. In order to overcome the above problems, a thermite plugging and abandonment technology is proposed in this field. The technology uses the aluminothermic reaction to melt the original or set material for sealing. The natural convection under different confinement conditions directly affects the heat flux transfer in the heat transfer process. In order to study the melting effect of the thermite reaction on sandstone, based on the heat conduction theory, a heat conduction model based on the temperature release law of the thermite reaction was established. The numerical simulation results show that the surrounding heat transfer conditions are the key factors affecting the heat transfer effect in the axial and radial directions without considering the particle size and dosage of the thermite itself. This work is of great significance for studying the temperature law of thermite reaction release and the future research of thermite plugging and abandonment technology.

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44

Yeh, Chun-Liang, Kuan-Ting Chen, and Tzong-Hann Shieh. "Effects of Fe/Si Stoichiometry on Formation of Fe3Si/FeSi-Al2O3 Composites by Aluminothermic Combustion Synthesis." Metals 11, no. 11 (October 26, 2021): 1709. http://dx.doi.org/10.3390/met11111709.

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Aluminothermic combustion synthesis was conducted with Fe2O3–Al–Fe–Si reaction systems under Fe/Si stoichiometry from Fe-20 to Fe-50 at. % Si to investigate the formation Fe3Si/FeSi–Al2O3 composites. The solid-state combustion was sufficiently exothermic to sustain the overall reaction in the mode of self-propagating high-temperature synthesis (SHS). Dependence of iron silicide phases formed from SHS on Fe/Si stoichiometry was examined. Experimental evidence indicated that combustion exothermicity and flame-front velocity were affected by the Si percentage. According to the X-ray diffraction (XRD) analysis, Fe3Si–Al2O3 composites were synthesized from the reaction systems with Fe-20 and Fe-25 at.% Si. The increase of Si content led to the formation of both Fe3Si and FeSi in the final products of Fe-33.3 and Fe-40 at.% Si reaction systems, and the content of FeSi increased with Si percentage. Further increase of Si to Fe-50 at.% Si produced the FeSi–Al2O3 composite. Scanning electron microscopy (SEM) images revealed that the fracture surface morphology of the products featured micron-sized and nearly spherical Fe3Si and FeSi particles distributing over the dense and connecting substrate formed by Al2O3.

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45

Liu, Shou Ping, Jin Li, Xue Wei Lv, Zhi Gang Lun, Chen Guang Bai, and Sheng Fu Zhang. "Temperature Rising Behavior of Oxide Materials Synthesized V-Al Alloy and Slag after Reaction in Microwave Field." Advanced Materials Research 393-395 (November 2011): 401–6. http://dx.doi.org/10.4028/www.scientific.net/amr.393-395.401.

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The absorption of microwave energy has very close relationship with the structure and property of material. For the preparation of V-Al alloy with using microwave-assisted self-propagating, it is essential to choose the proper materials with suitable properties and quantities. The temperature-rise can be obtained by the interaction between microwave field and materials, and then the aluminothermic reaction can be controlled in the microwave field. In this paper, the temperature-rise behaviors of Al2O3, CaO, V2O5 and the slag after reaction under microwave field were investigated. The results showed that either the microwave power or the molecular structure of materials had significant effects on the heating rate. The relationship between temperature-rise behavior of different materials and the material structures were discussed through studying the difference of molecular structures, which led to the conclusion that the more structure defects in the crystal, the faster the heating rate was.

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46

La, Pei Qing, Xue Feng Lu, Yang Yang, Ya Ping Bai, and Yu Peng Wei. "Effects of Annealing on Microstructure and Mechanical Properties of Bulk Nanocrystalline Fe₃Al Based Alloy Prepared by Aluminothermic Reaction." Materials Science Forum 688 (June 2011): 57–61. http://dx.doi.org/10.4028/www.scientific.net/msf.688.57.

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Анотація:

The effects of annealing on microstructure and mechanical properties of bulk nanocrystalline Fe3Al based alloy with 10 wt. % Ni prepared by aluminothermic reaction have been investigated. It was found that crystal structure of the alloy did not change after annealing at 600 and 800 °C, while it changed to ordered B2and nanocrystalline grains orientations became random after annealing at 1000 °C. Average grain sizes of the alloy changed a little after annealing at different temperatures. The alloy after annealing had a large plastic deformation in compression at room temperature and the alloy annealed at 800 °C had the highest compressive yield strength of 1351 MPa. The alloy without annealing had much lower flow stress and good creep property in compression at 800 and 1000°C.

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47

Yeh, Chun Liang, and Wen Jung Yang. "Combustion Synthesis of (Ti,V)₂AlC Solid Solutions." Advanced Materials Research 909 (March 2014): 19–23. http://dx.doi.org/10.4028/www.scientific.net/amr.909.19.

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(Ti,V)2AlC solid solutions with Al2O3 addition were produced by solid state combustion involving aluminothermic reduction in the mode of self-propagating high-temperature synthesis (SHS). Starting materials included Ti/V2O5/Al/Al4C3 and TiO2/V2O5/Al/Al4C3 powder mixtures. Attempts were made to obtain (Ti1-xVx)2AlC with a broad substitution percentage. Combustion exothermicity was increased by increasing V2O5 for the yield of a higher proportion of V at the substitution site, which not only increased the combustion temperature and reaction front velocity, but also facilitated the evolution of (Ti,V)2AlC. The Ti-containing samples showed higher reaction exothermicity and better product formation than those adopting TiO2. As a result, (Ti1-xVx)2AlC with x from 0.2 to 0.8 was produced from the samples composed of the Ti/V2O5/Al/Al4C3 mixture. The (Ti,V)2AlC/Al2O3 composites synthesized in this study exhibited a laminated microstructure with closely-stacked (Ti,V)2AlC slabs of about 0.30.8 μm.

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48

Wang, Zhong Xun, Shu Ai Zhang, Qin Xing, Bao Shan Liu, and Gang Zhang. "Study on Coating Material and Preparation Technology of Aluminum Alloy Tube by Low Temperature Self-Propagating Molding." Materials Science Forum 1026 (April 2021): 157–62. http://dx.doi.org/10.4028/www.scientific.net/msf.1026.157.

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Low temperature self-propagating forming coating material system for aluminum alloy cylinder parts was designed with Al, Fe2O3, Mo, Cu, Ni and Ti powders as raw materials. Low temperature self-propagating wear-resistant coating was prepared on the inner wall of aluminum alloy cylinder parts by thermal spraying ignition condensation centrifugal self-propagating fusion technology. XRD, DSC and SEM were used to study the microstructure, thermodynamic properties and cross-section morphology of the coating after thermal reaction of four kinds of low-temperature self-propagating materials with different proportions. The preparation process parameters of the coating were optimized by orthogonal test, including the amount of coating, the rotation speed of self-propagating centrifuge and the reaction time of self-propagating coating. The results show that the addition of Si, Mo and Zn powders in the four low temperature self-propagating powder systems can reduce the occurrence temperature of aluminothermic reaction; the optimal process parameters for coating preparation are rotational speed of 2000r/min, powder filling amount of 0.9g/cm3 and rotational reaction time of 16S.The results show that the coating with 20wt.% Al, 60wt.% Fe2O3, 12wt.% Si, 4wt.% Mo and 4wt.% Zn has better density and interface adhesion.

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49

Vivekananda, A. S., S. Balasivanandha Prabu, and R. Paskaramoorthy. "Processing-structure-property correlations of in situ Al/TiB2 composites processed by aluminothermic reduction process." Science and Engineering of Composite Materials 25, no. 5 (September 25, 2018): 869–79. http://dx.doi.org/10.1515/secm-2017-0014.

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AbstractThis paper reports the influence of process parameters on the size and distribution of in situ titanium diboride (TiB2) particles within the aluminium (Al) matrix. TiB2 particles were formed as a result of the in situ reaction of potassium hexafluorotitanate (K2TiF6) and potassium tetra fluoroborate (KBF4) with molten Al. Two process parameters, namely, the addition time (AT) and holding time (HT) of precursor salts, were considered. The Al/TiB2 composites were produced by allowing the in situ reaction to occur at various ATs (10, 20, and 30 min) and HTs (20, 30, and 40 min). Results showed that the formation of TiB2 was confirmed by XRD analysis. The microstructure, TiB2 particle size, hardness, yield strength (YS), and ultimate tensile strength (UTS) were strongly affected by the said process parameters. The variations in hardness and UTS were highly consistent with those found in the microstructure of the composites. Compared with the Al parent material, the increase in the average hardness and UTS of the composite were 51% and 44%, respectively. This improvement was achieved for the composite sample fabricated with 20 min of AT and 30 min of HT. At this condition, the composite displayed near-uniform particle distribution.

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50

La, Pei Qing, Xin Guo, Yang Yang, Chun Jie Cheng, Xue Feng Lu, and Yu Peng Wei. "Effects of Annealing on Microstructure and Mechanical Properties of Bulk Nanocrystalline Fe3Al Based Alloy with 10 Wt. % Mn Prepared by Aluminothermic Reaction." Advanced Materials Research 236-238 (May 2011): 1939–44. http://dx.doi.org/10.4028/www.scientific.net/amr.236-238.1939.

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Microstructure and mechanical properties of bulk nanocrystalline Fe3Al based alloy with 10 wt. % Mn prepared by aluminothermic reaction after annealing at 600, 800 and 1000°C for 8 h were investigated in order to gain insights in effects of annealing. Crystal structure of the alloy did not change and a fiber phase with enriched Mn appeared in the annealed alloy. Grain size of the alloy changed a little after annealing at 600°C but increased a lot after annealing at 800 and 1000°C. The annealed alloy had plasticity in compression at room temperature and the alloy annealed at 1000°C had yield strength of 782 MPa. The alloy without annealing has creep properties in compression at 800 and 1000°C and can be easily hot rolled to strip and sheet.

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