Articles de revues : « Al2TiO5 based model refractory materials »

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Borysenko, Oksana, Sergii Logvinkov, Halyna Shabanova, Igor Остапенко et Vita Шумейко. « GEOMETRICAL–TOPOLOGICAL CHARACTERISTICS OF THE SUBSOLIDUS STRUCTURE IN THE MgO – Al2O3 – TiO2 SYSTEM ». Bulletin of the National Technical University "KhPI". Series : Chemistry, Chemical Technology and Ecology, n^o 1(5) (15 mai 2021) : 18–23. http://dx.doi.org/10.20998/2079-0821.2021.01.03.

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Among the materials that attract attention from the point of view of creating refractory products with increased heat resistance, one can single out materials based on compositions of the MgO – Al2O3 – TiO2 system. As a result of the thermodynamic analysis of the MgO – Al2O3 – TiO2 system, it was found that the partition of the system into elementary triangles will change in three temperature ranges: I – up to 1537 K, II – in the temperature range 1537 – 2076 K and above 2076 K. It has been established that up to a temperature of 2076 K there is a concentration range of spinel phases: magnesium aluminate spinel – quandylite. Above 1537 K, there is a concentration range: tialite – karroite, which meets the requirements for materials with high heat resistance. The elementary triangle TiO2 – Al2TiO5 – MgTi2O5 can be used to obtain heat–resistant materials based on Al2TiO5 stabilized by MgTi2O5. To obtain heat–resistant periclase–spinel materials, an elementary triangle Mg2TiO4 – MgAl2O4 – MgO is recommended, in which only compounds with a cubic crystal lattice are present. Thus, the division of the MgO – Al2O3 – TiO2 system into elementary triangles and the analysis of the geometrical–topological characteristics of the phases of the system made it possible to select in the system under study the regions of compositions that have optimal properties for obtaining materials with the specified optimal properties.

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Epicier, T., G. Thomas, H. Wohlfromm et J. S. Moya. « High resolution electron microscopy study of the cationic disorder in Al2TiO5 ». Journal of Materials Research 6, n^o 1 (janvier 1991) : 138–45. http://dx.doi.org/10.1557/jmr.1991.0138.

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As part of a research program devoted to the microstructural characterization of Al2TiO5-based compounds, high resolution electron microscopy (HREM) has been undertaken in order to study the crystallographic arrangement, especially ordering possibilities, of Al and Ti cations in the metallic sublattice of aluminum titanate. It is seen that adequate experimental conditions, mainly defocus setting, for a resolution of at least 2.5 Å point-to-point, enable the disordered model to be directly and unambiguously proved on 100-oriented micrographs.

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Dhupal, D., B. Doloi et B. Bhattacharyya. « Optimization of process parameters of Nd:YAG laser microgrooving of Al2TiO5 ceramic material by response surface methodology and artificial neural network algorithm ». Proceedings of the Institution of Mechanical Engineers, Part B : Journal of Engineering Manufacture 221, n^o 8 (1 août 2007) : 1341–50. http://dx.doi.org/10.1243/09544054jem814.

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The high-intensity pulsed Nd:YAG laser has the capability to produce both deep grooves and microgrooves on a wide range of engineering materials such as ceramics, composites, and diamond. The micromachining of ceramics is highly demanded in industry because of its wide and potential uses in various fields such as automobile, electronic, aerospace, and biomedical engineering. Engineering ceramic, i.e. aluminium titanate (Al2TiO5), has tremendous application in the automobile and aero-engine industries owing to its excellent thermal properties. The present paper deals with the artificial neural network (ANN) and response surface methodology (RSM) based mathematical modelling and also an optimization analysis of the machining characteristics of the pulsed Nd:YAG laser during the microgrooving operation on Al2TiO5. The experiments were planned and carried out based on design of experiments (DOE). Lamp current, pulse frequency, pulse width, assist air pressure, and cutting speed were considered as machining process parameters during the pulsed Nd:YAG laser microgrooving operation and these parameters were also utilized to develop the ANN predictive model. The response criteria selected for optimization were upper width, lower width, and depth of the trapezoidal microgroove. The optimal process parameter settings were obtained as an assist air pressure of 1.2944 kgf/cm2, lamp current of 19.3070A, pulse frequency of 1.755 kHz, pulse width of 5.7087 per cent of duty cycle, and cutting speed of 10mm/s for achieving the desired upper width, lower width, and depth of the laser microgroove. The output of the RSM optimal data was validated through experimentation and the ANN predictive model. A good agreement is observed between the results based on the ANN predictive model and the actual experimental observations.

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Sagadin, Christoph, Stefan Luidold, Christoph Wagner, Christoph Pichler, Daniel Kreuzer, Alfred Spanring, Helmut Antrekowitsch, Amy Clarke et Kester Clarke. « Thermodynamic Refractory Corrosion Model for Ferronickel Manufacturing ». Metallurgical and Materials Transactions B 52, n^o 2 (24 février 2021) : 1052–60. http://dx.doi.org/10.1007/s11663-021-02077-x.

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AbstractA thermodynamic model, based on SimuSage, was developed to simulate refractory corrosion between a magnesia-based refractory material and ferronickel (FeNi) slags. The model considers a theoretical cross-section of a refractory material to simulate a ferronickel smelter application. The current model is structured into 10 zones, which characterize different sectors in the brick (hot to cold side) perpendicular to the refractory surface with an underlying temperature gradient. In each zone, the model calculates the equilibrium between the slag and a specified amount of refractory material. The emerging liquid phases are transferred to subsequent zones. Meanwhile, all solids remain in the calculated zone. This computational process repeats until a steady state is reached in each zone. The simulation results show that when FeNi slag infiltrates into the refractory material, the melt dissolves the magnesia-based refractory and forms silicates (Mg,Fe,Ca)2SiO4 and Al spinel ((Mg,Fe)Al2O4). Furthermore, it was observed that iron oxide from the slag reacts with the refractory and generates magnesiowustite (Mg,Fe)O. Practical lab-scale tests and scanning electron microscopy (SEM)/Energy Dispersive X-ray Spectroscopy (EDS) characterization confirmed the formation of these minerals. Finally, the refractory corrosion model (RCM) ultimately provides a pathway for improving refractory lifetimes and performance.

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Ricoeur, Andreas, et Dimitri Henneberg. « Two Scale-Based Continuum Damage Model for Brittle Materials under Thermomechanical Loading ». Key Engineering Materials 525-526 (novembre 2012) : 589–92. http://dx.doi.org/10.4028/www.scientific.net/kem.525-526.589.

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Ceramic refractory materials initially contain a multitude of defects such as voids, microcracks, grain boundaries etc. Particularly being exposed to high temperatures above 1000 °C the macroscopic properties such as effective compliance, strength and lifetime are essentially determined by microscopic features of the material. The deformation process and failure mechanisms are going along with the creation of new microdefects as well as the growth and coalescence of cracks. A brittle material damage model for dynamic thermomechanical loading conditions is presented in this paper. Representative volume elements (RVE) include microcrack initiation and growth. The material laws are formulated on the continuum level using appropriate homogenisation methods. To demonstrate the potential of the numerical tools, two examples are presented which are taken from applications. Based on experiments, cyclic thermal shock tests at refractory plates are simulated by FEM. To quantify the thermal shock resistance of ceramics, experiments suggested by Hasselman are simulated numerically supplying a critical temperature slope.

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Grigoriev, Aleksandr S., Andrey I. Dmitriev et Evgeniy V. Shil’ko. « Evaluation of local mechanical properties of SiO2-based ceramic refractories using microscale modeling ». Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mekhanika, n^o 80 (2023) : 73–84. http://dx.doi.org/10.17223/19988621/80/7.

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The development of multiscale mechanical models of promising refractory materials is an urgent problem in the mechanics of solids. One of the reasons is the applicability of these models when creating digital twins of advanced refractories. The authors of this paper recently developed and validated a mesoscopic model of the SiO2-based refractory material that is widely used in metallurgy. This model takes into account the characteristic structural features of SiO2 refractory in the scale range of 10-5 - 10-2 m and the mechanical behavior features in a wide range of strain rates. However, the full use of the model requires knowledge of local mechanical properties of mesoscopic structural elements, in particular, the highly porous regions, which are formed by fine grains less than 102 pm in size. An experimental study of effective mechanical characteristics of such regions is an extremely difficult task. Therefore, the purpose of this work is to obtain the theoretical estimate using the microscale numerical simulation of highly porous regions of SiO2 refractory material and to determine their integral mechanical characteristics. To study this problem, the two-dimensional model samples are developed that simulate fine-grained regions of the refractory and are characterized by different porosity and pore structure types (channel-like or closed type). The intervals of the variation of Young’s modulus and strength characteristics of the samples are obtained depending on the porosity and morphology of the pore space. The contribution of the closed-type porosity to the integral mechanical characteristics of the refractory is determined; though, the volume fraction of such pores is low as compared to that of the channel-like pores. The obtained data will be used as input parameters of mesoscale refractory models for solving the urgent problems related to the study of the effect of microstructure parameters on the macroscopic mechanical and thermomechanical properties of SiO2-based refractories.

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Wang, Zhi Gang, Chang Ming Liu, Nan Li et Yuan Wang. « Prediction of Properties of MgO-C Refractory Based on Micromechanics Model ». Applied Mechanics and Materials 37-38 (novembre 2010) : 890–94. http://dx.doi.org/10.4028/www.scientific.net/amm.37-38.890.

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The microstructures of materials determine their properties. Micromechanics is one of the effective methods by which the quantitative relationship between the microstructure of the material and macroscopical mechanical properties can be established. In this paper, the mechanical properties of matrix phase from two different MgO-C refractories were predicted by using micromechanics model. Then, the predicted results were explained based on their different microstructures and compositions. It was proved that the method provides a new approach for researching the mechanical properties of refractories.

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Yan, Xiaobing, Gong Wang, Jianhui Zhao, Zhenyu Zhou, Hong Wang, Lei Zhang, Jingjuan Wang et al. « Memristors mimicking the regulation of synaptic plasticity and the refractory period in the phenomenological model ». Journal of Materials Chemistry C 8, n^o 15 (2020) : 5183–90. http://dx.doi.org/10.1039/d0tc00575d.

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Li, Bin, Ke Peng, Chen-Hao Yang et Xu-Hui Zhang. « Optimization method for clamping layout of refractory thin-wall parts based on IAGA-Elman ». Journal of Physics : Conference Series 2760, n^o 1 (1 mai 2024) : 012055. http://dx.doi.org/10.1088/1742-6596/2760/1/012055.

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Abstract Thin-walled parts made of refractory materials are widely used in the sintering field of lithium battery powder materials. To solve the problem of deformation and fracture caused by the low stiffness of refractory thin-wall parts, a sandwich-layout proxy optimization model based on the IAGA-Elman neural network and sub-optimization mechanism was proposed. Based on ABAQUS, finite element simulation models under different clamping layouts were obtained. The sample set required for neural network training was established, a sub-optimization mechanism with MSP+EI combination plus point criterion as the target task was constructed, and the IAGA algorithm was used to optimize the Elman neural network for optimal parameter seeking. The deep nonlinear mapping relationship between clamping layout parameters and clamping deformation is explored by proxy optimization model. The experimental results show that the proposed method can predict the clamping deformation of thin-walled parts with fewer simulations and higher fitting accuracy, and can provide a basis for the optimal design of the clamping layout of refractory thin-walled parts.

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Spyridakos, Athanasios, Dimitrios E. Alexakis, Isaak Vryzidis, Nikolaos Tsotsolas, George Varelidis et Efthimios Kagiaras. « Waste Classification of Spent Refractory Materials to Achieve Sustainable Development Goals Exploiting Multiple Criteria Decision Aiding Approach ». Applied Sciences 12, n^o 6 (16 mars 2022) : 3016. http://dx.doi.org/10.3390/app12063016.

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The recycling of used refractory materials in the heavy industry constitutes one of the significant environmental problems in the industry related to environmental and financial issues. This study proposes a multicriteria methodological frame to characterize the refractory material waste and identify the recycling capabilities. Considering the chemical and physical analysis of the refractory material wastes, the proposed methodological frame progresses into a two-phase procedure. The first phase includes an on/off approach that allows discretizing the refractory material wastes to compatible or not compatible as far as their recycling prospects. Then, an additive value model is utilized, including (a) the marginal value functions used for every criterion related to critical environmental factors, and (b) the weight vector reflecting the relative importance of the criteria used. A group of experts concerning the environment and the refractory materials was employed to estimate the additive value model. The assessment of the marginal value function is achieved using the module of the Multicriteria Interactive Intelligence Decision Aiding System (MIIDAS), which is based on a modification of the mid-value split point technique incorporating focused dialogues, artificial intelligence, and visual techniques. The weight vector was assessed using the weight assessment through prioritization method (WAP), which concludes with the estimation of the weights based on the criteria ranking and the pairwise expression of the strength of preferences for the consecutive criteria according to their ranking. The outcome of this approach is to introduce an environmental appropriateness index for refractory materials based on their chemical composition and the judgement of an expert group. The main findings of this research may be useful for engineers, decision-makers, and scientists in the field of circular economy and waste management.

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Zhang, Chengbo, Binbin Hou, Lei Shao, Zongshu Zou et Henrik Saxén. « Estimation of the Blast Furnace Hearth State Using an Inverse-Problem-Based Wear Model ». Metals 12, n^o 8 (3 août 2022) : 1302. http://dx.doi.org/10.3390/met12081302.

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An undisturbed and well-controlled hearth state is an essential prerequisite for achieving a long campaign life and low production costs in an ironmaking blast furnace, because hearth wear and hot metal and slag drainage are crucial factors in its operation. With the objective to estimate the hearth state of the refractory of a three-taphole blast furnace, a wear model of the hearth erosion and skull formation was developed. The model is based on thermocouple readings in the hearth lining and solves an inverse heat conduction problem for a series of co-axial vertical slices, where the erosion and skull lines are optimized simultaneously. The model is optimized for fast computation by adopting a novel procedure featuring fixed mesh during the looping calculation. The results revealed that the hearth refractory showed an elephant-foot-shaped profile with excessive erosion in the hearth periphery, indicating that liquid flows are suppressed in the hearth bottom and that the permeability of the core of the deadman is low. These findings were further elaborated and confirmed by a comparison between the estimated hearth state and other key operation variables, including the coke rate, blast kinetic energy, and residual carbon appetite of the hot metal.

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C., Chijioke, Okoye P., Igwegbe W. E. et Ugwuegbulam J.C. « PREDICTING THE COMPRESSIVE STRENGTH OF PBA – CLAY REFRACTORY BRICKS USING RESPONSE SURFACE METHOD ». International Journal of Research -GRANTHAALAYAH 6, n^o 6 (30 juin 2018) : 472–79. http://dx.doi.org/10.29121/granthaalayah.v6.i6.2018.1392.

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The importation of refractory materials is one of the biggest challenges industries faced in third world countries, of which Nigerian is one of them. The addition of palm bunch ash to clay in the production of clay bricks is one of the ways refractory materials are produced. The clay used here was Nsu clay. This work looked at the compressive strength of refractory bricks which is one of the properties of refractory materials. The work eliminates the traditional methods of trial and error and the rigorous mathematical analysis associated with the formation of some regression models in the prediction of some properties of refractory bricks. This was achieved by the use of Surface Response method. A regression model to predict the strength of a refractory brick was formulated, the model was found to be adequate based of the analysis of variance in which the Rsq, Rsq (adjusted) and Rsq (prediction) were found to be adequate, hence the model can be used to predict the compressive strength of refractory bricks. The optimal compressive strength was found to be 30.1513KN/m2 at a ratio of 1:0.2570 at a water/clay ratio of 4.2590. Also, from the results it can be seen that the compressive strength of bricks decrease with increase in the percentages of palm bunch ash.

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Bhandari, Uttam, Congyan Zhang, Congyuan Zeng, Shengmin Guo, Aashish Adhikari et Shizhong Yang. « Deep Learning-Based Hardness Prediction of Novel Refractory High-Entropy Alloys with Experimental Validation ». Crystals 11, n^o 1 (7 janvier 2021) : 46. http://dx.doi.org/10.3390/cryst11010046.

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Hardness is an essential property in the design of refractory high entropy alloys (RHEAs). This study shows how a neural network (NN) model can be used to predict the hardness of a RHEA, for the first time. We predicted the hardness of several alloys, including the novel C0.1Cr3Mo11.9Nb20Re15Ta30W20 using the NN model. The hardness predicted from the NN model was consistent with the available experimental results. The NN model prediction of C0.1Cr3Mo11.9Nb20Re15Ta30W20 was verified by experimentally synthesizing and investigating its microstructure properties and hardness. This model provides an alternative route to determine the Vickers hardness of RHEAs.

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Bhandari, Uttam, Congyan Zhang, Congyuan Zeng, Shengmin Guo, Aashish Adhikari et Shizhong Yang. « Deep Learning-Based Hardness Prediction of Novel Refractory High-Entropy Alloys with Experimental Validation ». Crystals 11, n^o 1 (7 janvier 2021) : 46. http://dx.doi.org/10.3390/cryst11010046.

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Hardness is an essential property in the design of refractory high entropy alloys (RHEAs). This study shows how a neural network (NN) model can be used to predict the hardness of a RHEA, for the first time. We predicted the hardness of several alloys, including the novel C0.1Cr3Mo11.9Nb20Re15Ta30W20 using the NN model. The hardness predicted from the NN model was consistent with the available experimental results. The NN model prediction of C0.1Cr3Mo11.9Nb20Re15Ta30W20 was verified by experimentally synthesizing and investigating its microstructure properties and hardness. This model provides an alternative route to determine the Vickers hardness of RHEAs.

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Sheng, Dong-Yuan, et Christian Windisch. « A Simulation-Based Digital Design Methodology for Studying Conjugate Heat Transfer in Tundish ». Metals 12, n^o 1 (28 décembre 2021) : 62. http://dx.doi.org/10.3390/met12010062.

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The successful design of refractory lining for a tundish is critical due to the demand of superheat control, improvement of steel cleanliness and reduction in material cost during continuous casting. A design of experiment analysis, namely, the Taguchi method, was employed to analyze two-dimensional heat transfer through refractory linings of a single-strand tundish, with the consideration of the thickness and the thermal conductivity of lining materials. In addition, a three-dimensional conjugate heat transfer model was applied in the tundish, taking in account the molten steel flow and heat conduction in the linings. A special focus of this study was to demonstrate the analysis methodology of combining Taguchi and CFD modelling to explore lining design in terms of thickness and thermal conductivity for the given process conditions during tundish operations.

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Dmitriev, Andrey N., M. O. Zolotykh, K. Chen et Galina Yu Vitkina. « The Thermophysical Bases of Monitoring of the Fireproof Lining Wear in the Blast Furnace Hearth ». Defect and Diffusion Forum 370 (janvier 2017) : 113–19. http://dx.doi.org/10.4028/www.scientific.net/ddf.370.113.

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This paper presents a two-dimensional description of the temperature field in refractory lining of the hearth in the blast furnace. The mathematical model is based on Fourier differential heat conduction equation. Different solutions of this equation are presented and the optimal quantity and location of thermosensors in the hearth is proposed. This paper also presents a methodology to obtain the heat conductivity of refractory materials.

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Zhu, Liguang, Yanan Jia, Zengxun Liu, Caijun Zhang, Xingjuan Wang et Pengcheng Xiao. « Mass-Transfer Model for Steel, Slag, and Inclusions during Ladle-Furnace Refining ». High Temperature Materials and Processes 37, n^o 7 (26 juillet 2018) : 665–74. http://dx.doi.org/10.1515/htmp-2017-0011.

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AbstractPrecise control of inclusion and molten steel compositions during ladle-furnace refining is important to obtain high-quality steel. Mass-transfer behavior affects these compositions. A model was developed to investigate the mass transfer occurring between molten steel, slag, inclusions, and the refractory during ladle-furnace refining, using two-film theory to describe the reactions. A coupled-reaction model based on the CaO–Al2O3–MgO–SiO2–FeO–P2O5 slag and Mn–Si–Al–Ca–Mg–P–S–O steel systems was applied to describe the reactions between molten steel and slag; the reactions between the refractory lining and slag or steel were described using average industrial erosion rate data. The model was used to calculate changes in the compositions of molten steel and slag, oxygen activity at the slag–molten steel interface, and composition of the inclusions. The calculated results agreed with operational results for a 100 t ladle furnace at the Tangsteel plant in China.

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Helle, Mikko, Henrik Saxén, Bart de Graaff et Cornelis van der Bent. « Wear-Model-Based Analysis of the State of Blast Furnace Hearth ». Metallurgical and Materials Transactions B 53, n^o 1 (4 janvier 2022) : 594–603. http://dx.doi.org/10.1007/s11663-021-02399-w.

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AbstractThe condition and state of the hearth of the blast furnace is of considerable importance since the life length of the refractories governs the campaign length of the furnace, but it is also of significance as it affects the drainage of iron and slag and the hot metal temperature and composition. The paper analyses the hearth of a blast furnace using a model of the lining wear based on the solution of an inverse heat conduction problem, studying the changes in the lining state throughout the campaign. Different operation states are detected, characterized by smooth and efficient hot metal production and by erratic behavior with large disturbances in the hearth state. During the periods of poor performance, the hearth exhibits a cycling state with stages of excessive skull growth on the unworn refractory, followed by periods of dissolution of the skull and lining erosion. An explanation of the transitions is sought by a stating and solving a force balance for the deadman with the aim to clarify whether it is floating or sitting. A connection between the thermal cycles in the hearth and the hot metal sulfur content is finally demonstrated.

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Trumbulovic, Ljiljana, Zvonko Gulisija, Zagorka Acimovic-Pavlovic et Lj Andric. « Influence of the cordierite lining on the lost foam casting process ». Journal of Mining and Metallurgy, Section B : Metallurgy 39, n^o 3-4 (2003) : 475–87. http://dx.doi.org/10.2298/jmmb0304475t.

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This paper discuss the influence of the refractory cordierite lining on the structure and mechanical properties of Al-Si and Al-Cu casings obtained from the Lost foam casting process. So far there has not been any report of the research on cordierite lining in the literature and moreover the cordierite ceramics have never been used in foundries. In the light of these facts this paper investigates the possibility of using cordierite for manufacturing evaporable model refractory linings. Our results indicate that the application of cordierite ceramics is comparable to talc-based refractory linings in both Al-Cu and Al-Si castings, while cordierites are favorable in Al-Cu case due to their higher melting temperature.

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Zhao, Shu Mao, Wei Yang, Jie Sun et Zhi Xie. « Grain Gradation Design for Al₂O₃-MgO-C Refractories Based on Close Packing Theories ». Advanced Materials Research 508 (avril 2012) : 63–66. http://dx.doi.org/10.4028/www.scientific.net/amr.508.63.

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In this study, raw materials in five different commercially available size ranges were mixed to prepare blank for Al2O3-MgO-C refractories. In the light of close packing theory, the optimization model for getting the optimum grain gradation was founded. And optimum ratio for raw materials of different size and distribution character was concluded by solving the model to obtain closest packing. The result shows that stacking density and tap density of the blank came from the particle mixture with optimized grain gradation reached 1.46 and 1.70g/cm3 individually, both were higher than those of the blank made of mixture according to empirical grain gradation. And the microstructures observation result indicated that the voids among aggregate particles in the refractory came from the mixture with optimized grain gradation were separated into small and discrete ones while they were bigger in the refractory produced following empirical grain gradation.

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Barati, Hadi, Menghuai Wu, Susanne Michelic, Sergiu Ilie, Abdellah Kharicha, Andreas Ludwig et Youn-Bae Kang. « Mathematical Modeling of the Early Stage of Clogging of the SEN During Continuous Casting of Ti-ULC Steel ». Metallurgical and Materials Transactions B 52, n^o 6 (20 octobre 2021) : 4167–78. http://dx.doi.org/10.1007/s11663-021-02336-x.

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AbstractThe clogging of the submerged entry nozzle (SEN) during the continuous casting of steel can be divided into two stages: the “early stage,” when the initial layer of the clog covers the SEN refractory surface owing to chemical reactions, and the “late stage,” when the clog layer continues to grow because of the deposition of non-metallic inclusions (NMIs). In this paper, a mathematical formulation is proposed for the build-up of the initial oxide. The chemical reaction mechanism is based on the work of Lee and Kang (Lee et al. in ISIJ Int 58:1257–1266, 2018): a reaction among SEN refractory constituents produces CO gas, which can re-oxidize the steel melt and consequently form an oxide layer on the SEN surface. The proposed formulation was further incorporated as a sub-model in a transient clogging model, which was previously developed by the current authors to track the late stage of clogging. The thermodynamics and kinetics of CO production, depending on the local pressure and temperature, must be considered for the sub-model of early-stage clogging. Test simulations based on a section of an actual industrial SEN were conducted, and it was verified that the clogging phenomenon is related to the SEN refractory, the chemical reaction with the steel melt, the local temperature and pressure, and the transport of NMIs by the turbulent melt flow in the SEN. The model was qualitatively validated through laboratory experiments. The uncertainty of some parameters that govern the reaction kinetics and permeability of the oxide layer is discussed.

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Bhandari, Uttam, Hamed Ghadimi, Congyan Zhang, Shizhong Yang et Shengmin Guo. « Predicting Elastic Constants of Refractory Complex Concentrated Alloys Using Machine Learning Approach ». Materials 15, n^o 14 (18 juillet 2022) : 4997. http://dx.doi.org/10.3390/ma15144997.

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Refractory complex concentrated alloys (RCCAs) have drawn increasing attention recently owing to their balanced mechanical properties, including excellent creep resistance, ductility, and oxidation resistance. The mechanical and thermal properties of RCCAs are directly linked with the elastic constants. However, it is time consuming and expensive to obtain the elastic constants of RCCAs with conventional trial-and-error experiments. The elastic constants of RCCAs are predicted using a combination of density functional theory simulation data and machine learning (ML) algorithms in this study. The elastic constants of several RCCAs are predicted using the random forest regressor, gradient boosting regressor (GBR), and XGBoost regression models. Based on performance metrics R-squared, mean average error and root mean square error, the GBR model was found to be most promising in predicting the elastic constant of RCCAs among the three ML models. Additionally, GBR model accuracy was verified using the other four RHEAs dataset which was never seen by the GBR model, and reasonable agreements between ML prediction and available results were found. The present findings show that the GBR model can be used to predict the elastic constant of new RHEAs more accurately without performing any expensive computational and experimental work.

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Huang, A., P. Lian, L. Fu, H. Gu et Y. Zou. « Modeling and experiment of slag corrosion on the lightweight alumina refractory with static magnetic field facing green metallurgy ». Journal of Mining and Metallurgy, Section B : Metallurgy 54, n^o 2 (2018) : 143–51. http://dx.doi.org/10.2298/jmmb171014002h.

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Electromagnetic field is applied widely in metallurgy and other high temperature processes, and affects the behavior of melts. The lightweight alumina based carbon free refractory is of importance for energy-saving, consumption reduction and high quality steel production, and the slag corrosion resistance is significant concerning its service life. Does electromagnetic field control the slag corrosion behavior on the lightweight alumina refractory? In this paper, a multi-field coupled model was established to describe the slag corrosion process in an electromagnetic field. The mathematical modeling in combination of experiments was applied to clarify slag corrosion behavior of lightweight alumina refractory in static magnetic field. The simulation results agree with that of the experiments, which means the proposed model is promising for slag corrosion modeling. The results show that the combination of the slag properties change, and electromagnetic damping caused by MHD (magnetohydrodynamics) effect can enhance the slag corrosion resistance by inhibiting slag penetration and promoting formation of a directional isolation layer, and be beneficial to high-quality clean steel production.

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Jones, Morgan E., Steve Fearn, Rudolf Winter, Fajin Yuan, Alistair R. Lennie, Julia E. Parker, Stephen P. Thompson et Chiu C. Tang. « Dynamic strain propagation in nanoparticulate zirconia refractory ». Journal of Applied Crystallography 48, n^o 2 (21 février 2015) : 386–92. http://dx.doi.org/10.1107/s1600576715002393.

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Residual and intrinsic strains in granular materials have been studied extensively. However, understanding the dynamic strains that cause these resultant residual strains is key to developing better strain-resistant materials. This investigation demonstrates a method for characterizing dynamic strain propagation in granular materials. The specimen is a zirconia-based refractory composed of sol–gel-derived zirconia nanoparticles in a potassium silicate glass binder.In situsynchrotron X-ray powder diffraction in flat-plate geometry is used to characterize the sample structure on timescales of the order of 1 ms. A 125 W CO2laser is used to strain the sample with a 25 ms pulse length. To compensate for the poor flux on this timescale, a pump–probe method is repeated 1000 times and the resulting data are subsequently re-binned to improve statistics. A Gaussian weighting function is also used to introduce better contrast between strained and unstrained frames.TOPAS Academicis used for fitting with a Le Bail model in `batch mode'. Lattice parameters and sample height are refined during fitting, along with a Lorentzian line width for extracting microstrain broadening. Microstrains, ∊, in the range of 1.01 < ∊ < 1.46% are reported on a 1 ms timescale.

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Yao, Hao, Huiting Chen, Yao Ge, Han Wei, Ying Li, Henrik Saxén, Xuebin Wang et Yaowei Yu. « Numerical Analysis on Erosion and Optimization of a Blast Furnace Main Trough ». Materials 14, n^o 17 (26 août 2021) : 4851. http://dx.doi.org/10.3390/ma14174851.

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The main trough of a blast furnace (BF) is a main passage for hot metal and molten slag transportation from the taphole to the torpedo and the slag handling. Its appropriate working status and controlled erosion ensure a safe, stable, high-efficiency and low-cost continuous production of hot metal. In this work, the tapping process of a main trough of a BF in the east of China was numerically studied with the help of a CFD library written in C++, called OpenFOAM, based on the use of the Finite Volume Method (FVM). The results show that turbulence intensity downstream of the hot metal impact position becomes weaker and the turbulence area becomes larger in the main trough. During the tapping, thermal stress of wall refractory reaches the maximum value of 1.7 × 107 Pa at the 4 m position in the main trough. Furthermore, baffles in the main trough placed between 5.8 m and 6.2 m were found to control and reduce the impact of the turbulence on the refractory life. The metal flowrate upstream of the baffles can be decreased by 6%, and the flow velocity on the upper sidewall and bottom wall decrease by 9% and 7%, respectively, compared with the base model. By using baffles, the minimum fatigue life of the refractory in the main trough increases by 15 tappings compared with the base model, so the period between the maintenance stops can be prolonged by about 2 days.

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GOROG, J. PETER, JAMES G. HEMRICK, HARALD A. WALTER, W. RAY LEARY et MURRAY ELLIS. « Design of refractory linings for balanced energy efficiency, uptime, and capacity in lime kilns ». February 2015 14, n^o 2 (1 mars 2015) : 141–51. http://dx.doi.org/10.32964/tj14.2.141.

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In this work a computer model is used to examine how refractory linings with both high alumina and basic refractory bricks affect kiln operations. Recommendations are made based on the results to aid mill personnel in designing optimized refractory linings for specific situations. Kilns used to regenerate lime in the kraft process are highly energy intensive. Throughout the 1990s, in response to increasing fuel prices, the pulp and paper industry primarily used backup insulation in conjunction with high alumina brick to line calcining zones of their kilns. The dramatic decline in price of natural gas over the past decade, in combination with mounting pressures to increase production of existing assets, has led many mills to focus more on increasing uptime and capacity rather than on energy savings. To this end, a growing number of mills are using basic (magnesia based) brick instead of high alumina brick to line calcining zones. While the use of basic brick can increase the uptime and reduce the cost to maintain the refractory lining, it can dramatically increase the shell temperatures and heat losses. Tradeoffs, therefore, are created among energy efficiency, capacity, and uptime.

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Seyed Mahmoud, Seyed Mohammad Ali, Ghader Faraji, Mostafa Baghani, Mohammad Saber Hashemi, Azadeh Sheidaei et Majid Baniassadi. « Design of Refractory Alloys for Desired Thermal Conductivity via AI-Assisted In-Silico Microstructure Realization ». Materials 16, n^o 3 (27 janvier 2023) : 1088. http://dx.doi.org/10.3390/ma16031088.

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A computational methodology based on supervised machine learning (ML) is described for characterizing and designing anisotropic refractory composite alloys with desired thermal conductivities (TCs). The structural design variables are parameters of our fast computational microstructure generator, which were linked to the physical properties. Based on the Sobol sequence, a sufficiently large dataset of artificial microstructures with a fixed volume fraction (VF) was created. The TCs were calculated using our previously developed fast Fourier transform (FFT) homogenization approach. The resulting dataset was used to train our optimal autoencoder, establishing the intricate links between the material’s structure and properties. Specifically, the trained ML model’s inverse design of tungsten-30% (VF) copper with desired TCs was investigated. According to our case studies, our computational model accurately predicts TCs based on two perpendicular cut-section images of the experimental microstructures. The approach can be expanded to the robust inverse design of other material systems based on the target TCs.

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Gong, Zhen-Xiang, et Arun S. Mujumdar. « Development of Drying Schedules for One-Side-Heating Drying of Refractory Concrete Slabs Based on a Finite Element Model ». Journal of the American Ceramic Society 79, n^o 6 (juin 1996) : 1649–58. http://dx.doi.org/10.1111/j.1151-2916.1996.tb08777.x.

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Betts, Keith A., Per-Olof Thuresson, Federico Felizzi, Ella X. Du, Ibou Dieye, Jia Li, Mathias Schulz et Anthony S. Masaquel. « US cost–effectiveness of polatuzumab vedotin, bendamustine and rituximab in diffuse large B-cell lymphoma ». Journal of Comparative Effectiveness Research 9, n^o 14 (octobre 2020) : 1003–15. http://dx.doi.org/10.2217/cer-2020-0057.

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Aim: To evaluate the cost–effectiveness of polatuzumab vedotin (pola) + bendamustine + rituximab (BR) in relapsed/refractory diffuse large B-cell lymphoma based on the GO29365 trial from a US payer’s perspective. Materials & methods: A partitioned survival model used progression-free survival and overall survival data from the GO29365 trial. The base case analysis assumed overall survival was informed by progression-free survival; a mixture cure model estimated proportion of long-term survivors. Results: In the base case, pola + BR was cost-effective versus BR at US$35,864 per quality-adjusted life year gained. Probabilistic and one-way sensitivity analyses showed that the findings were robust. Conclusion: Pola + BR is cost-effective versus BR for the treatment of transplant-ineligible relapsed/refractory diffuse large B-cell lymphoma in the US.

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Xiang, Junchen, Haoyu Shi, Xueyu Huang et Daogui Chen. « Improving Graphite Ore Grade Identification with a Novel FRCNN-PGR Method Based on Deep Learning ». Applied Sciences 13, n^o 8 (21 avril 2023) : 5179. http://dx.doi.org/10.3390/app13085179.

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Graphite stone is widely used in various industries, including the refractory, battery making, steel making, expanded graphite, brake pads, casting coatings, and lubricants industries. In the mineral processing industry, an effective and accurate diagnostic method based on FRCNN-PGR is proposed and evaluated, which involves cutting images to expand the dataset, combining them using the faster R-CNN model with high and low feature layers, and adding a global attention mechanism, Relation-Aware Global Attention Network (RGA), to extract features of interest from both the space and channel. The proposed model outperforms the original faster R-CNN model with 80.21% mAP and 87.61% recall on the split graphite mine dataset.

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Makarov, V. N., R. G. Akhmetov, S. Ya Davydov et N. V. Makarov. « Research and modeling of the ecological efficiency of drying refractory and building materials in vertical shaft furnaces ». NOVYE OGNEUPORY (NEW REFRACTORIES), n^o 7 (30 novembre 2023) : 52–59. http://dx.doi.org/10.17073/1683-4518-2023-7-52-59.

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Based on the hypothesis of the dominant effect on the environmental efficiency of drying materials in shaft furnaces of the concentration, median diameter, dispersion, temperature and humidity of dust particles at the outlet of the dryer, a device for thermal aeration separation of dust is proposed. The analysis of mathematical modeling of aerothermodynamic processes in a two-phase medium asbestos dust ‒ gas flow confirmed the conclusions of industrial studies on the influence of aerothermodynamic parameters of direct flow on the temperature and humidity of asbestos dust in the pneumatic dryer. Based on the principle of additive classification, a mathematical model of aeration separation of dust particles directly in the dryer of the shaft furnace is constructed, depending on the parameters of the heat carrier and the proposed device.

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Klimenko, Denis, Nikita Stepanov, Jia Li, Qihong Fang et Sergey Zherebtsov. « Machine Learning-Based Strength Prediction for Refractory High-Entropy Alloys of the Al-Cr-Nb-Ti-V-Zr System ». Materials 14, n^o 23 (26 novembre 2021) : 7213. http://dx.doi.org/10.3390/ma14237213.

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The aim of this work was to provide a guidance to the prediction and design of high-entropy alloys with good performance. New promising compositions of refractory high-entropy alloys with the desired phase composition and mechanical properties (yield strength) have been predicted using a combination of machine learning, phenomenological rules and CALPHAD modeling. The yield strength prediction in a wide range of temperatures (20–800 °C) was made using a surrogate model based on a support-vector machine algorithm. The yield strength at 20 °C and 600 °C was predicted quite precisely (the average prediction error was 11% and 13.5%, respectively) with a decrease in the precision to slightly higher than 20% at 800 °C. An Al13Cr12Nb20Ti20V35 alloy with an excellent combination of ductility and yield strength at 20 °C (16.6% and 1295 MPa, respectively) and at 800 °C (more 50% and 898 MPa, respectively) was produced based on the prediction.

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Liu, Zhangquan, Xiaohui Shi, Min Zhang et Junwei Qiao. « High-Temperature Mechanical Properties of NbTaHfTiZrV0.5 Refractory High-Entropy Alloys ». Entropy 25, n^o 8 (26 juillet 2023) : 1124. http://dx.doi.org/10.3390/e25081124.

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The NbTaHfTiZrV0.5 is a refractory multi-principal-element alloy with high strength and good ductility at room temperature. It is important for possible high-temperature applications to investigate the deformation mechanism of the NbTaHfTiZrV0.5 alloy at different temperatures using tensile tests. In this investigation, the tensile tests were conducted at room temperature to 1273 K on sheet materials fabricated by cold rolling combined with annealing treatments. At 473 K, the NbTaHfTiZrV0.5 alloy exhibited a high tensile ductility (12%). At a testing temperature range of 673~873 K, the ductility was reduced, but the yield strength remained above 800 MPa, which is rare in most other alloys. The TEM investigations revealed that a dislocation slip controlled the plastic deformation, and the degree of deformation was closely related to the dislocation density. The true stress–strain curves of the alloy under different deformation conditions were obtained by tensile deformation at different deformation temperatures (673~873 K) and strain rates (0.001~0.0005 s−1). Experimental results were utilized to construct the parameters of a constitutive model based on a traditional mathematical model to predict the flow behavior at high temperatures. The excellent high-temperature mechanical properties of the NbTaHfTiZrV0.5 alloy will enable it to be used in several engineering applications.

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Mhandu, Takunda Joseph, Ilhwan Park, Sanghee Jeon, Sohta Hamatsu, Yogarajah Elakneswaran, Mayumi Ito et Naoki Hiroyoshi. « A Pretreatment of Refractory Gold Ores Containing Sulfide Minerals to Improve Gold Leaching by Ammonium Thiosulfate : A Model Experiment Using Gold Powder and Arsenic-Bearing Sulfide Minerals ». Metals 13, n^o 8 (28 juillet 2023) : 1357. http://dx.doi.org/10.3390/met13081357.

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The use of thiosulfate to extract gold from refractory ores is promising because of its non-toxicity and high selectivity. Sulfide minerals (i.e., pyrite, arsenopyrite, chalcopyrite), major gold carriers in refractory gold ores, however, hinder gold extraction due to the high consumption of a lixiviant. In this study, a new method to improve gold extraction from sulfide bearing gold ores is proposed based on the model experiments using a mixture of gold powder and arsenopyrite-bearing sulfide (HAsBS) ore. The effects of HAsBS ore on gold leaching in ammonium thiosulfate solutions were investigated, and it was found that gold extraction in the presence of HAsBS ore was suppressed because of the unwanted decomposition of thiosulfate on the surface of sulfide minerals. To improve gold extraction in the presence of the sulfide minerals, this study investigated the effects of the pretreatment of HAsBS ore using ammonium solutions containing cupric ions and confirmed that HAsBS ore was oxidized in the pretreatment and its surface was covered by the oxidation products. As a result, thiosulfate consumption was minimized in the subsequent gold leaching step using ammonium thiosulfate, resulting in an improvement in gold extraction from 10% to 79%.

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Jayaram, Raman, et M. K. Miller. « An atom-probe field ion-microscope investigation of γ-γ' interfaces in a model nickel-based superalloy ». Proceedings, annual meeting, Electron Microscopy Society of America 50, n^o 1 (août 1992) : 176–77. http://dx.doi.org/10.1017/s0424820100121284.

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Nickel-based superalloys are of great technological interest because of their attractive mechanical properties at high temperatures. Their ability to maintain high strength under extreme conditions of thermal cycling makes them highly suitable for applications such as turbine blade material for aircraft engines. Single crystal nickel-based superalloys containing refractory elements such as Mo, Ta and Re have received considerable attention on account of their high creep strength at elevated temperatures. In these materials, the Ll2-ordered γ' phase is initially present as discrete cuboids in the disordered γ matrix. During high temperature creep, with the stress applied along the <100> direction, these cuboids directionally coarsen to form continuous γ' lamellae perpendicular to the applied-stress axis. The improvement in creep strength that occurs as a result of this change in the γ' morphology has been attributed to a number of different possible mechanisms. One mechanism suggested is the segregation of molybdenum to the γ-γ' interface which could impede dislocations producing increased creep strength.

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Gruber, Dietmar, Sheng Li Jin et Harald Harmuth. « Simulation of Refractory Fracture as a Tool for Advanced Material Testing ». Advances in Science and Technology 92 (octobre 2014) : 232–41. http://dx.doi.org/10.4028/www.scientific.net/ast.92.232.

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The work presented here deals with simulation assisted evaluation of fracture testing of ordinary ceramic refractory materials. Two tests are applied. One of them, a wedge splitting test, is already established for this purpose. An inverse evaluation procedure was developed to derive more information from the test results: It enables the simultaneous determination of the specific fracture energy, the tensile strength and the Young’s modulus. Moreover specific fracture energy can also be determined in the case that the test has to be interrupted at some residual load due to relatively low material brittleness. The other test method, a laser irradiation disc test, was developed in order to determine specific fracture energy and tensile strength for fine ceramic refractory materials behaving relatively brittle. From the time elapsed until crack initiation occurs (t1) and a stable/instable transition of crack propagation takes place (t2), respectively, the tensile strength and the specific fracture energy are calculated based on a simulation of the mode I fracture behavior which applies the fictitious crack model according to Hillerborg.

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Locci, A. M., A. Cincotti, F. Delogu, R. Orrù et G. Cao. « Combustion synthesis of metal carbides : Part I. Model development ». Journal of Materials Research 20, n^o 5 (mai 2005) : 1257–68. http://dx.doi.org/10.1557/jmr.2005.0152.

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The definition of a rigorous theoretical framework for the appropriate physico-chemical description of self-propagating high-temperature synthesis (SHS) processes represents the main goal of this work which is presented in two sequential articles. In this article, a novel mathematical model to simulate SHS processes is proposed. By adopting a heterogeneous approach for the description of mass transfer phenomena, the model is based on appropriate mass and energy conservation equations for each phase present during the system evolution. In particular, it takes microstructural evolution into account using suitable population balances and properly evaluating the differentdriving forces from the relevant phase diagram. The occurrence of phase transitionsis treated on the basis of the so-called enthalpy approach, while a conventional nucleation-and-growth mechanistic scenario is adopted to describe quantitatively the formation of reaction products. The proposed mathematical model may be applied to the case of combustion synthesis processes involving a low melting point reactant and a refractory one, as for the synthesis of transition metal carbides from pure metal and graphite. Thus, the model can be profitably used to gain a deeper insight into the microscopic elementary phenomena involved in combustion synthesis processes through a suitable combination of experimental and modeling investigations, as it may be seen in Part II of this work [J. Mater. Res. 20, 1269 (2005)].

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Zhang, Yu, Rohit Deshpande, D. Huang, Pinakin Chaubal et Chenn Q. Zhou. « A Methodology for Blast Furnace Hearth Inner Profile Analysis ». Journal of Heat Transfer 129, n^o 12 (3 avril 2007) : 1729–31. http://dx.doi.org/10.1115/1.2768100.

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The wear of a blast furnace hearth and the hearth inner profile are highly dependent on the liquid iron flow pattern, refractory temperatures, and temperature distributions at the hot face. In this paper, the detailed methodology is presented along with the examples of hearth inner profile predictions. A new methodology along with new algorithms is proposed to calculate the hearth erosion and its inner profile. The methodology is to estimate the hearth primary inner profile based on 1D heat transfer and to compute the hot-face temperature using the 3D CFD hearth model according to the 1D preestimated and reestimated profiles. After the hot-face temperatures are converged, the hot-face positions are refined by a new algorithm, which is based on the difference between the calculated and measured results, for the 3D computational fluid dynamics (CFD) hearth model further computations, until the calculated temperatures well agree with those measured by the thermocouples.

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Маевский, К. К. « Численное исследование ударно-волнового нагружения металлических композитов на базе W и WC ». Журнал технической физики 91, n^o 5 (2021) : 815. http://dx.doi.org/10.21883/jtf.2021.05.50694.293-20.

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The results of research on modeling shock-wave loading of metal composites – elkonites, which are sintered refractory materials tungsten, tungsten carbide or molybdenum impregnated with fusible metal silver or copper using thermodynamically equilibrium model TEC are presented. The investigation of the compressibility of such composites are related to the properties of the materials themselves and the possibility of creating samples based on them. Thermodynamic characteristics are calculated for these metals and compared with available data of shock-wave experiments. The model allows us to describe the dynamic loading of solid and porous alloys of various compositions such as Cu–W, Ag–W, Cu–WC, Ag-W. This model allows for targeted selection of material compositions of different porosity values and ratios of their components in order to obtain the specified characteristics for shock-wave loading of samples.

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Маевский, К. К. « Численное исследование ударно-волнового нагружения металлических композитов на базе W и WC ». Журнал технической физики 91, n^o 5 (2021) : 815. http://dx.doi.org/10.21883/jtf.2021.05.50694.293-20.

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The results of research on modeling shock-wave loading of metal composites – elkonites, which are sintered refractory materials tungsten, tungsten carbide or molybdenum impregnated with fusible metal silver or copper using thermodynamically equilibrium model TEC are presented. The investigation of the compressibility of such composites are related to the properties of the materials themselves and the possibility of creating samples based on them. Thermodynamic characteristics are calculated for these metals and compared with available data of shock-wave experiments. The model allows us to describe the dynamic loading of solid and porous alloys of various compositions such as Cu–W, Ag–W, Cu–WC, Ag-W. This model allows for targeted selection of material compositions of different porosity values and ratios of their components in order to obtain the specified characteristics for shock-wave loading of samples.

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Popov, V. N. « Simulation of crystallization of the melt modified by nanoscale particles during laser treatment of a metal surface ». Physics and Chemistry of Materials Treatment 1 (2021) : 5–14. http://dx.doi.org/10.30791/0015-3214-2021-1-5-14.

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A 2D mathematical model is proposed for the modification of an iron-based alloy with refractory nanosized particles. Numerical simulation of the processes during the modification of the surface layer of the substrate metal using the energy of a laser pulse has been carried out. Within the framework of the proposed model, the processes of heating and melting of metal on a substrate covered with a layer of nanosized refractory particles penetrating into the molten metal, convective heat transfer in the melt, and solidification after the end of the pulse are considered. Metal melting is considered in the Stefan approximation, and when the melt is cooled, the model of heterogeneous nucleation and subsequent crystallization is used. The fluid flow is described by the Navier-Stokes equations in the Boussinesq approximation. The distribution of nanoparticles in the melt is modeled by moving markers. Based on the results of calculations, the mode of pulsed laser action is determined, in which a flow is formed for a homogeneous distribution of particles of the modifying substance in the presence of a surfactant in the metal. The volume of the solid phase formed around the nucleus determines the size of the grain structure in the solidified alloy. The liquidus temperature changes depending on the concentration of dissolved carbon in the melt. In the numerical simulation of the solidification of the surface layer of the metal, it was found that the conditions of nucleation and crystallization differ significantly in the volume of the melt. It is determined that the duration of nucleation in a supercooled melt is several tens of microseconds. The maximum number of crystallization centers occurs in areas where heat removal occurs most rapidly. With the growth of the solid phase in the melt and the release of the latent heat of crystallization, the value of supercooling decreases, the nucleation stops and the number of formed crystallization centers does not change further. The distribution of the dispersion of the crystal structure over the volume of the melted metal is estimated. It was found that as the melt cools, sequential-volume crystallization occurs.

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Buljak, Vladimir, Severine Bavier-Romero et Achraf Kallel. « Calibration of Drucker–Prager Cap Constitutive Model for Ceramic Powder Compaction through Inverse Analysis ». Materials 14, n^o 14 (20 juillet 2021) : 4044. http://dx.doi.org/10.3390/ma14144044.

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Phenomenological plasticity models that relate relative density to plastic strain are frequently used to simulate ceramic powder compaction. With respect to the form implemented in finite element codes, they need to be modified in order to define governing parameters as functions of relative densities. Such a modification increases the number of constitutive parameters and makes their calibration a demanding task that involves a large number of experiments. The novel calibration procedure investigated in this paper is based on inverse analysis methodology, centered on the minimization of a discrepancy function that quantifies the difference between experimentally measured and numerically computed quantities. In order to capture the influence of sought parameters on measured quantities, three different geometries of die and punches are proposed, resulting from a sensitivity analysis performed using numerical simulations of the test. The formulated calibration protocol requires only data that can be collected during the compaction test and, thus, involves a relatively smaller number of experiments. The developed procedure is tested on an alumina powder mixture, used for refractory products, by making a reference to the modified Drucker–Prager Cap model. The assessed parameters are compared to reference values, obtained through more laborious destructive tests performed on green bodies, and are further used to simulate the compaction test with arbitrary geometries. Both comparisons evidenced excellent agreement.

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Vlahović, Milica, Ana Alil, Aleksandar Devečerski, Dragana Živojinović et Tatjana Volkov-Husović. « Non-Destructive Examination for Cavitation Resistance of Talc-Based Refractories with Different Zeolite Types Intended for Protective Coatings ». Materials 16, n^o 16 (11 août 2023) : 5577. http://dx.doi.org/10.3390/ma16165577.

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In many industrial processes that include fluid flow, cavitation erosion of different engineering structures (pumps, turbines, water levels, valves, etc.) during their operation is expected. Metallic, ceramic, and composite materials are usual candidates considered for application in such extreme conditions. In this study, the idea is to synthesize refractory ceramic material based on talc with the addition of zeolite for utilization as protective coatings in cavitating conditions. Two talc-based refractories with zeolites from two Serbian deposits were produced. The behaviors of the samples in simulated cavitation conditions were examined by an advanced non-destructive methodology consisting of monitoring mass loss and surface degradation using image analysis compiled with principal component analysis (PCA), interior degradation by ultrasonic measurements, and the microstructure by a scanning electron microscope (SEM). Lower mass loss, surface degradation level, and modeled strength decrease indicated better cavitation resistance of the sample with Igros zeolite, whereby measured strength values validated the model. For the chosen critical strength, the critical cavitation period as well as critical morphological descriptors, Area and Diameter (max and min), were determined. A Young’s elasticity modulus decrease indicated that surface damage influence progressed towards interior of the material. It can be concluded that the proposed methodology approach is efficient and reliable in predicting the materials’ service life in extreme conditions.

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Zuev, A. V., Yu P. Zarichnyak et D. Ya Barinov. « MEASUREMENT OF THERMOPHYSICAL PROPERTIES RIGID FIBER INSULATION ». Proceedings of VIAM, n^o 2 (2021) : 88–98. http://dx.doi.org/10.18577/2307-6046-2021-0-2-88-98.

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Describes a mathematical model for processing the results of measurements of thermal conductivity of highly porous fibrous materials of thermal protection. The results and some methodological features of measuring the thermal conductivity of rigid thermal insulation based on refractory oxide fibers are presented. The possibility of measurements taking into account the anisotropy of properties is investigated. The stiffness of the thermal insulation at the fiber contacts is provided by the binder. Thermal conductivity was measured by the stationary method on cylindrical samples in a wide temperature range from 20 to 1700 °C in various gaseous media.

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Aneggi, Eleonora, Sajid Hussain, Walter Baratta, Daniele Zuccaccia et Daniele Goi. « Enhanced Heterogeneous Fenton Degradation of Organic Dyes by Bimetallic Zirconia-Based Catalysts ». Molecules 29, n^o 9 (30 avril 2024) : 2074. http://dx.doi.org/10.3390/molecules29092074.

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The qualitative impact of pollutants on water quality is mainly related to their nature and their concentration, but in any case, they determine a strong impact on the involved ecosystems. In particular, refractory organic compounds represent a critical challenge, and several degradation processes have been studied and developed for their removal. Among them, heterogeneous Fenton treatment is a promising technology for wastewater and liquid waste remediation. Here, we have developed mono- and bimetallic formulations based on Co, Cu, Fe, and Mn, which were investigated for the degradation of three model organic dyes (methylene blue, rhodamine B, and malachite green). The treated samples were then analyzed by means of UV-vis spectrophotometry techniques. Bimetallic iron-based materials achieved almost complete degradation of all three model molecules in very short time. The Mn-Fe catalyst resulted in the best formulation with an almost complete degradation of methylene blue and malachite green at pH 5 in 5 min and of rhodamine B at pH 3 in 30 min. The results suggest that these formulations can be applied for the treatment of a broad range of liquid wastes comprising complex and variable organic pollutants. The investigated catalysts are extremely promising when compared to other systems reported in the literature.

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Peng, Jing, Fang Li, Bin Liu, Yong Liu, Qihong Fang, Jia Li et Peter K. Liaw. « Mechanical properties and deformation behavior of a refractory multiprincipal element alloy under cycle loading ». Journal of Micromechanics and Molecular Physics 05, n^o 04 (décembre 2020) : 2050014. http://dx.doi.org/10.1142/s2424913020500149.

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In comparison with the state-of-the-art Ni-based superalloys, refractory multiprincipal element alloys (MPEAs) exhibit considerably higher strengths at temperatures above 1600[Formula: see text]C, which can be a significant potential required in the high demand for aerospace applications. However, the atomic-scale work-hardening behavior of such important materials during low-cycle loading remain unknown. Here, using molecular dynamics simulations, we study the low-cycle fatigue of nanocrystalline refractory multiprincipal element alloy with different grain sizes, to reveal the cyclic deformation, work hardening and damage mechanism. As a result, an extensive grain growth is observed during the cyclic deformation, thus driving the dynamic Hall–Petch strengthening mechanism. For the model with large grain size, the glide of partial dislocations with screw structure can be responsible for the deformation behavior under cyclic loading, and at small grain size the grain growth-coordinated deformation twinning can control the plastic process. The deformation twin boundaries generated during the cyclic loading show high stability, while the remaining high-angle grain boundaries are highly unstable. The initial softening followed by hardening depends upon the dislocation density and grain size. In particular, atomic-scale element segregation occurs after cyclic loading. This study gives a cyclic deformation micromechanism, and thus accelerates the design and development of superior fatigue-resistant refractory multiprincipal element alloy over a wide temperature range.

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Eriş, Rasim, M. Vedat Akdeniz et Amdulla O. Mekhrabov. « On the Optimization of the Microstructural and Mechanical Properties of Model Ni-Based Superalloys Through the Alloying Effects of Refractory Mo and W Elements ». Metallurgical and Materials Transactions A 53, n^o 5 (21 mars 2022) : 1859–72. http://dx.doi.org/10.1007/s11661-022-06642-0.

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Li, Sheng Hao, Ao Huang, Yun Tao Qu, Xin Lu, Hua Zhi Gu et Guang Qiang Li. « Mathematical Simulation and Physical Modeling of Self-Source Magnetization by Liquid Electrolyte Flow ». Materials Science Forum 982 (mars 2020) : 165–72. http://dx.doi.org/10.4028/www.scientific.net/msf.982.165.

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With the increasing requirements for steel quality, the refining conditions are increasing strict. The high-speed movement of molten steel under mechanical or pneumatic agitation can uniform the temperature and composition, and accelerate the collision of the inclusions to eliminate. However, the electromagnetic field has an important influence on the removal of inclusions in steel and the corrosion of refractory materials. The magnetic phenomenon caused by the movement of molten steel needs to be explored. Considering the complexity of high temperature thermal simulation, this work adopted the physical modeling combined with mathematical simulation method, saturated sodium chloride solution was selected to simulate molten steel as a liquid electrolyte, the magnetic phenomenon caused by solution motion was tested and analyzed, and mathematical model of solution motion magnetization was based on discharge mechanism and magnetic vector potential superposition principle, then the variation law of spatial magnetic field generated by liquid electrolyte flow was discussed. The results show that the simulation results agree with that of the physical modeling, and the mathematical model is promising for prediction of the magnetic field generated by liquid electrolyte flow. Under a constant flow speed of 2000 r/min, a magnetic field with magnetic flux density up to 0.15 Gs was produced, which has a significant effect on the refractory corrosion and removal of impurities in the molten steel.

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Parshin, Sergey G., Alexey M. Levchenko et Pengfei Wang. « Metallurgy and Mechanism of Underwater Wet Cutting Using Oxidizing and Exothermic Flux-Cored Wires ». Materials 14, n^o 16 (18 août 2021) : 4655. http://dx.doi.org/10.3390/ma14164655.

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This paper considers the metallurgical processes of dissociation, ionization, oxidation, deoxidation, and dissolution of oxides during underwater wet cutting. A multiphase mechanism of underwater wet cutting consisting of working and idle cycles of the electrical process in a pulsating vapor gas bubble is proposed. A model of arc penetration into metal due to metal oxidation and stabilization of the arc by the inner walls of a narrow kerf is proposed. For underwater cutting of 10 KhSND, 304L steel, CuAl5, and AlMg4.5Mn0.7 alloy, we provide a principle of modeling the phase composition of the gas mixture based on high oxygen concentration, improving ionization, enthalpy, heat capacity, and thermal conductivity of plasma through the use of a mixture of KNO3, FeCO3 and aluminum. The method of improving the thermophysical properties and ionization of plasma due to the exothermic effect when introducing Fe3O4, MoO2, WO2 oxides and Al, Mg, Ti deoxidizers is proposed. Although a negative effect of refractory slag was revealed, it could be removed by using the method of reducing surface tension through the ionic dissolution of refractory oxides in Na3AlF6 cryolite. In underwater cutting of 10 KhSND and 304L, the steel welding current was 344–402 A with a voltage of 36–39 V; in cutting of CuAl5 and AlMg4.5Mn0.7 alloy, the welding current was 360–406; 240 A, with a voltage of 35–37; 38 V, respectively, with the optimal composition of flux-cored wire: 50–60% FeCO3 and KNO3, 20–30% aluminum, 20% Na3AlF6. Application of flux-cored wires of the KNO3-FeCO3-Na3AlF6-Al system allowed stable cutting of 10KhSND, AISI 304L steels, and CuAl5 bronze with kerf width up to 2.5–4.7 mm.

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McSherry, Sean, et Andrej Lenert. « Design of a gradient epsilon-near-zero refractory metamaterial with temperature-insensitive broadband directional emission ». Applied Physics Letters 121, n^o 19 (7 novembre 2022) : 191702. http://dx.doi.org/10.1063/5.0122535.

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Gradient epsilon-near-zero (ENZ) metamaterials offer broadband directional control over thermal emission. Implementing this approach using materials that remain stable in harsh thermo-chemical environments would allow it to be broadly deployed in thermal photonics. Our prior work showed that heterostructures of rock salt MgO and perovskite BaZr0.5Hf0.5O3 (BZHO) are stable up to 1100 °C in air, with no discernible intermixing. In this work, we design a gradient ENZ metamaterial made from three lattice-matched refractory oxides: MgO, BZHO, and NiO. The miscibility of MgO and NiO makes it possible to linearly vary the ENZ frequency of the metamaterial layers. BZHO is used as a thin, interlayer diffusion barrier. We model the emissivity of our gradient ENZ metamaterial at 25 and 1000 °C to demonstrate that the spectral bandwidth of directional emission is preserved at high temperatures despite changes in the optical properties of each material. Finally, we discuss practical fabrication challenges associated with the back reflector and offer potential solutions based on advancements in hetero-integration. Overall, this work shows a pathway toward gradient ENZ metamaterials with ultrahigh-temperature stability.

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