Refractory Research Articles

Using the Ca ii Lines in T Tauri Stars to Infer the Abundance of Refractory Elements in the Innermost Disk Region

We present a study of the abundance of calcium in the innermost disk of 70 T Tauri stars in the star-forming regions of Chamaeleon I, Lupus, and Orion OB1b. We use calcium as a proxy for the refractory material that reaches the inner disk. We used magnetospheric accretion models to analyze the Ca ii emission lines and estimate abundances in the accretion flows of the stars, which feed from the inner disks. We find Ca depletion in disks of all three star-forming regions, with 57% of the sample having [Ca/H] < –0.30 relative to the solar abundance. All disks with cavities and/or substructures show depletion, consistent with trapping of refractories in pressure bumps. Significant Ca depletion ([Ca/H] < –0.30) is also measured in 60% of full disks, although some of those disks may have hidden substructures or cavities. We find no correlation between Ca abundance and stellar or disk parameters except for the mass accretion rate onto the star. This could suggest that the inner and outer disks are decoupled, and that the mass accretion rate is related to a mass reservoir in the inner disk, while refractory depletion reflects phenomena in the outer disk related to the presence of structure and forming planets. Our results of refractory depletion and timescales for depletion are qualitatively consistent with expectations of dust growth and radial drift, including partitioning of elements, and constitute direct evidence that radial drift of solids locked in pebbles takes place in disks.

Assessing and tailoring the dilatometric profile of novel chromium‐free refractory raw materials

AbstractReducing dependence on toxic electrofused magnesia‐chromium aggregates is essential to meet demands for eco‐friendly refractories. Some authors have proposed alternative compositions using lab‐scale electrofusion to produce small specimens (&lt; 0.5 g). However, this size limits the evaluation of key refractory properties, such as thermal expansion. As an alternative, this study explored conventional sintering at 1600°C for 5 h and both methods resulted in equivalent chemical and mineralogical compositions. Despite presenting higher porosity (24 % – 30 %) than the electrofused ones (4 % – 6 %), consistent microstructural parameters supported using the sintering route to produce larger specimens (5 × 5 × 25 mm3), which were assessed for dilatometric profiles up to 1400°C. Combined with thermodynamic calculations, Rietveld's refining of X‐ray diffraction patterns and differential scanning calorimetry, the dilatometric analysis indicated that spinel dissolution in the periclase causes a high expansion during heating, whereas its re‐precipitation results in shrinkage. As this behavior could result in challenges for the refractory lining design, computational thermodynamics was used to find additives capable of increasing this transition temperature. TiO₂ was identified as a promising candidate and its effectiveness was attested.

SOME PHYSICAL-CHEMICAL FEATURES THE SOLID PHASES HYDRAULICITY

The most widely used in composite materials industry are concrete installations bonded with different binders. Higher energy consumption and several ecological problems make their manufacture to become more and more expensive. The growing market of construction works and constant extension of real estate property increases the demand for cheap and new materials with desired features. As a result of many years intensive scientific researches there is now a practical possibility to offer an alternative and unique products technology of manufacture based on binding suspension (bricks, wall, heat insulating and refractory materials and other) – all of them of desired size and shape. The experience of the composite materials technology development shows that in comparison with traditional the microhardness of materials with an ultradispersive structure increases several times and the specific surface increases by an order contributing to a decrease in the sintering temperature. The longevity of similar material is essentially increasing provi­ded structure is forming under conditions of the servi­ce site. Thus, building industry will obtain improved service life and performance from binding suspensions as field installations will continue to move toward adopting and utilizing practices based on technology described herein, rather than on cement technology. Relative to conventional composite materials products with mechano-chemical binders will continue to gain in popularity because of the following advantages: low energy consumption and low prices for the products; ecological safety of the manufacture process and of the ready-made products; good mechanical and design properties; moisture and cold proofness; surface need not be fired; no shrinkage of the products after drying; simple to manufacture a variety of different products; ready availability and flexibility in design; absence of manufacture wastes.

Electron confinement-induced plasmonic breakdown in metals.

Plasmon resonance represents the collective oscillation of free electron gas density and enables enhanced light-matter interactions in nanoscale dimensions. Traditionally, the classical Drude model describes plasmonic excitation, wherein plasma frequency exhibits no spatial dispersion. Here, we show conclusive experimental evidence of the breakdown of plasmon resonance and a consequent metal-insulator transition in an ultrathin refractory plasmonic material, hafnium nitride (HfN). Epitaxial HfN thick films exhibit a low-loss and high-quality Drude-like plasmon resonance in the visible spectral range. However, as the film thickness is reduced to nanoscale dimensions, Coulomb interaction among electrons increases because of electron confinement, leading to the spatial dispersion of plasma frequency. With a further decrease in thickness, electrons lose their ability to shield the incident electric field, turning the medium into a dielectric. The observed metal-insulator transition might carry some signatures of Wigner crystallization and indicates that such transdimensional, between 2D and 3D, films can serve as a promising playground to study strongly correlated electron systems.

Characterization and Tribology Performance of Refractory Materials Coatings with Blast Furnace Slag (BFS) Fabricated by Thermal Spraying

Characterization and Tribology Performance of Refractory Materials Coatings with Blast Furnace Slag (BFS) Fabricated by Thermal Spraying

Thermal/mechanical properties of cordierite synthesized using coal gangue as a refractory material

AbstractCoal gangues i a solid waste during the coal mining process and the accumulation of coal gangue will harm the environment. Therefore, solid waste utilization of coal gangue is required to reduce the environmental damage. In this paper, cordierite ceramics are successfully prepared via a solid‐phase sintering using coal gangue, Al2O3, and MgO as raw materials. The effects of sintering temperatures on the microstructures, phase stability, and thermal properties of ceramics are investigated. The results show that the properties of cordierites prepared at 1200°C are close to those of prepared by the traditional method, and the synthesized ceramics have thermal expansion coefficients (TECs) and conductivity of 4.1–10−6 K−1 and 1.72 W·m−1 K−1 at 900°C, respectively. The sample prepared at 1200°C has good wear resistance (η) with a wear resistance coefficient of 0.507, and an excellent thermal shock resistance, which can withstand 15 times of cold and hot shocks at 1100°C without any cracks on the surface. This study systematically elucidates the thermal/mechanical properties of the synthesized cordierite, and the feasibility of using coal gangue as raw materials prepared cordierite ceramics as refractory materials. This work presents an effective solution to mitigate the challenge of coal gangue disposal.

Numerical Study of Complex Heat Transfer and Aerodynamics in a Tube Furnace with a Flat Fuel Combustion Mode

The object of the study is a tubular furnace for steam reforming of natural gas. The channel walls are formed by a refractory lining and a tubular screen with a known temperature. The chamber volume is filled with a selectively radiating, absorbing and weakly scattering medium of gaseous fuel combustion products. The research method is based on the numerical solution of a system of two-dimensional integro-differential equations of radiative gas dynamics, closed by a two-parameter model of turbulent convection. It is shown that when burners are located on the side walls of the radiation chamber, a significant restructuring of the heat flux distribution occurs. A decrease in the chamber width is accompanied by an increase in both radiant and convective heat fluxes to the tubular screen.

Glow-to-arc transition in graphite cathode with high-current magnetron discharge

The glow-to-arc transition is a critical phenomenon in plasma discharges, commonly leading to detrimental effects. The physical mechanisms triggering this transition remain poorly understood. The advent of a discharge called Hyper-Power Impulse Magnetron has opened possibilities. Hyper-Power Impulse Magnetron allows the glow mode to be maintained over long periods (1 ms) and at high-current densities (&amp;gt;5 A .cm−2), which has unveiled certain features in the glow-to-arc transition. This work focuses on a graphite target that transits easily in the arc regime. The high-speed video-camera analysis revealed specific properties of graphite in ExB discharges, and the statistical study of the arc transition revealed differences from other refractory target materials. The early stage of cathodic spot formation, observed as bright dots, will be presented and analyzed within the known “ecton” and “vaporization” models for spot formation. This experimental study highlights the role of luminous spot formation prior to arc transition, with possible optimization on the stability of magnetron discharges.

Assessment of Equilibrium between Yttrium and Oxygen in Liquid Iron

Rare earth elements (REEs) are crucial additives in the iron and steel industry. The accurate determination of thermodynamic data is fundamental for applying REEs in steel production; however, this has proven challenging due to their strong reactivity with refractory materials. This study assessed the thermodynamic data for the yttrium–oxygen equilibrium in liquid iron, using high‐temperature experiments with high‐purity Y2O3 crucibles as the smelting container. More reliable equilibrium constants and first‐order interaction coefficients are obtained by minimizing the reactions between yttrium and the crucible while ensuring favorable kinetic conditions. The results confirm that the deoxidation product of yttrium in liquid iron is Y2O3, and the equilibrium constant for the reaction Y2O3(s) = 2[Y] + 3[O] can be expressed as follows: . can be expressed as: . The first‐order interaction coefficient can be presented as: .

Structure Prediction and Mechanical Properties of Tantalum Carbide (TaC) on ab initio Level

AbstractTantalum carbide (TaC) is an extremely hard, brittle, refractory ceramic material with excellent physical properties, which makes it a desirable material in e. g. aerospace industries. In order to explore the range of feasible modifications of TaC, we have executed a crystal structure prediction study of the TaC chemical system using a multi‐methodological approach, via enthalpy landscape explorations of pristine TaC at different pressures, supplemented by data mining searches in the ICSD database. Local structure relaxations have been accomplished by using Density Functional Theory (DFT). The global minimum is found to correspond to the equilibrium rock salt (NaCl) type modification. Additionally, eight new phases of tantalum carbide are predicted to be feasible: the WC‐type, the NiAs‐type, the 5‐5‐type, the ZnS‐type, the RingTaC‐type, the CsCl‐type, the OrthoTaC‐type, and the TetraTaC‐type. Furthermore, the elastic and mechanical properties of the predicted TaC modifications were explored on the DFT level of computation. The promising values of some of the mechanical properties of the proposed tantalum carbide modifications suggest that various scientific, industrial, and technological applications of TaC should be possible.

A Novel Methodology to Quantify the Slag Protective Effect on the Oxidation Behavior of Oxide‐C Refractories

Preventing the oxidation of oxide‐C refractories used as working linings in steelmaking vessels is crucial for maintaining their performance and extending their lifetime. This study introduces a novel methodology for evaluating and quantifying the protective effect that adhered slag can have on the oxidation of the refractory lining of steelmaking ladles. The article details the ad‐hoc methodology itself, including the technique for adhering the slag to the refractory sample and the specifically developed equipment used. The proposed experimental approach includes the evaluation of how the environmental degradation of the slag layer affects the protection it provides to the refractory against attack by environmental oxygen. Finally, the methodology's ability to provide reliable and reproducible results is shown by its application on MgO–C refractories, the most widely used type of oxide‐C products in the steelmaking industry.

Research on the development of recycling technology for magnesium refractory materials

Abstract Magnesium refractory materials are rich in substances such as alumina and magnesium oxide, and the recycling and reuse of their waste is an important way to achieve energy conservation, environmental protection, and sustainable development of mineral resources. This article analyzes and elucidates the current recycling and utilization technologies of refractory materials from the perspectives of refractory waste used in desulfurization mixing heads, recycled magnesia carbon brick refractory materials, magnesia calcium brick refractory materials, and blast furnace lining refractory materials. By analyzing the key issues in the recycling and utilization technology of Magnesium refractory waste, important references are provided for the development direction of deep processing of high-quality refractory recycled products.

Statistical study of mechanical responses of ordinary refractory ceramics under cold crushing condition with discrete element modelling

Statistical study of mechanical responses of ordinary refractory ceramics under cold crushing condition with discrete element modelling

EXPLORING CERAMIC REFRACTORY MATERIALS: CLASSIFICATION AND TECHNOLOGICAL INNOVATIONS

The article explores the primary types of ceramic refractory materials, focusing on their properties and applications in high-temperature industrial processes. Key technological advancements in refractory manufacturing are discussed, with an emphasis on enhancing material strength, chemical resistance, and durability. The analysis highlights the specific characteristics of each refractory type, including fireclay, magnesite, corundum, and silicon carbide, and their utilization across various industries such as metallurgy, energy, and glass production. Modern production and modification methods for refractories are presented, aimed at improving thermal resistance and reducing the operational costs of equipment.

Waste refractory brick material added chitosan/oxidized pullulan complex gel production and removal of heavy metals from waste water

Wastewater is a by-product of numerous industrial processes that have been demonstrated to have adverse effects on human and natural health due to the pollutants it contains. The pollutants in these substances are organic or inorganic molecules and heavy metal ions that significantly harm the environment and human health. A variety of techniques have been devised for the removal of heavy metal ions from wastewater. The adsorption process has attracted significant attention due to its straightforward implementation, cost-effectiveness, and the environmentally friendly production of adsorbent materials using biocompatible substances. In this study, the removal of Cu2+ ions from wastewater was conducted using chitosan pullulan, a biocompatible and biodegradable polymer. In addition to chitosan and pullulan, waste refractory materials from a furnace used in iron and steel production were added to these polymer materials to increase the adsorption capacity. The initial step involved grinding the waste refractory brick material. Subsequently, chitosan was dissolved in acetic acid. After that, the refractory material was suspended in this solution, facilitating the formation of hydrogel beads using a NaOH solution. The obtained hydrogels were coated with pullulan to produce polyelectrolyte gel. Pullulan was oxidized to 6-carboxypullulan by the TEMPO (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) oxidation method and the negatively charged groups in its structure interacted with the positively charged groups in the chitosan structure to produce a complex gel. The chemical structure, morphological analysis, thermal analysis, and water release analysis of the produced waste refractory brick material added chitosan/oxidized pullulan complex gels were examined. The impact of the 6-carboxypullulan coating on the gels’ properties was elucidated. Furthermore, the adsorption of Cu2⁺ was conducted using solutions containing 100, 500, and 1000 ppm Cu2⁺ ions. It has been observed that the material can clean water with over 98% efficiency, even in solutions that exceed the standards set for wastewater. The material’s efficacy in cleaning solutions with concentrations above the standard for wastewater cleaning is evidence of its high performance. Furthermore, the kinetics and isotherm of the adsorption reaction were examined. The kinetics were determined to be consistent with the Pseudo Second Order (chemical reaction controlled) and aligned with the Langmuir and Freundlich Isotherm (mixed adsorption occurred on homogeneous and heterogeneous surfaces).

Comprehensive Screening of Plasma-Facing Materials for Nuclear Fusion

Plasma-facing materials (PFMs) represent one of the most significant challenges for the design of future nuclear fusion reactors. Inside the reactor, the divertor will experience the harshest material environment: intense bombardment of neutrons and plasma particles coupled with extremely large and intermittent heat fluxes. The material designated to cover this role in ITER is tungsten. While no other materials have shown the potential to match the properties of tungsten, many drawbacks associated with its application remain, including cracking and erosion induced by a low recrystallization temperature combined with a high ductile-brittle transition temperature and neutron-initiated embrittlement; surface morphology changes (helium bubbles and fuzz layer) due to plasma-tungsten interaction with subsequent risk of spontaneous material melting and delamination; and low oxidation resistance in the case of air contamination. Exploring alternatives to tungsten requires the design of a multivariable optimization problem. This work aims to produce a structured and comprehensive material screening of PFM candidates based on known inorganic materials. The method applied in this study to identify the most promising PFM candidates combines peer-reviewed data present in the PAULING FILE database and first-principles density-function theory calculations focusing on two key PFM defects—namely, the sputtering of surface atoms and the incorporation of interstitial hydrogen, respectively characterized by the surface binding energy and the interstitial formation energy. The crystal structures and their related properties, extracted from the PAULING FILE, are ranked according to the heat-balance equation of a PFM subjected to the heat loads in the divertor region of an ITER-like tokamak. The materials satisfying the requirements are critically compared with the state-of-the-art in plasma-facing materials research and in studies of refractory materials exposed to high temperatures, plasma, and neutron bombardment. This comparison assesses their thermo-mechanical properties under such conditions, identifying a subset of promising materials for first-principles electronic structure calculations. Most previously known and extensively studied PFMs, such as tungsten, molybdenum, and carbon-based materials, are captured by this screening process, confirming its reliability. Additionally, less familiar refractory materials suggest performance that calls for further investigations. Published by the American Physical Society 2024

Value Extraction from Ferrochrome Slag: A Thermochemical Equilibrium Calculation and Experimental Approach

The valorization of slag from the production of high-carbon ferrochrome is a challenge for ferrochrome producers. The recycling of high-carbon ferrochrome slag was explored through the smelting route to recover Fe–Si–Al–Cr alloys and reengineer the residual slag for alumina-enriched refractory material. In this research, the focus was to reduce the SiO2% and enrichment of Al2O3% in the final slag and recover the metallic value in the form of a complex alloy containing Fe, Si, Cr and Al. The manuscript consists of a thermochemical simulation of the smelting of FeCr slag followed by smelting experiments to optimize the process parameters such as temperature and the addition of coke, cast iron and alumina. An experimental investigation revealed that the maximum recovery of Si (57.4% recovery), Al in the alloy (20.56% recovery) and Al2O3 (85.78% recovery) in the slag was achieved at a charge mix consisting of 1000 g of FeCr slag, 300 g of alumina, 200 g of cast iron and 300 g of coke. The present study also demonstrated the usefulness of prior thermochemical calculations for smelting metallurgical wastes such as slag from high-carbon ferrochrome production for value creation and reutilization purposes.

Flexibilizing Mechanisms of Spinel-, Hercynite-, Galaxite-, and Chromite-Containing Basic Refractories for Cement Rotary Kilns

Background: Refractory linings of cement rotary kilns are subjected to severe thermomechanical stresses of cranking, ovality, tyre hooping/migration, and uneven thermal distribution. An insistent demand is to discover the significance of spinel, hercynite, galaxite, and chromite in magnesia refractories, as well as their flexibilizing mechanisms. Objectives: The objectives are to compare the fracture behavior of magnesia–spinel, – hercynite, -galaxite, and -chromite refractories and to unveil the flexibilizing mechanisms of different spinels. Methods: The wedge-splitting test is carried out to produce various fracture parameters. Their flexibilizing mechanisms are unveiled by performing microstructural observations and analyses. Results: Various fracture parameters are obtained, including specific fracture energy, brittleness number, characteristic crack length, and thermal-shock resistance parameter. Generally, magnesia–hercynite bricks and magnesia–galaxite bricks have demonstrated the obvious advantages of fracture resistance, which are more flexible than magnesia–spinel bricks and magnesia–chromite bricks. Conclusion: The flexibility of magnesia–spinel bricks is attributed to microcracks generated from the thermal mismatch between spinel grains and surrounding periclase, which is recognized as the thermal-expansion mismatch mechanism. In magnesia–hercynite and magnesia-galaxite refractories, the active-ion-diffusion mechanism is predominant beyond similar microcracks, to drive the flexibility by the continuous diffusion of Fe2+, Mn2+, and Mg2+ during high-temperature processes. In magnesia–chromite bricks, the pore rims contribute to the flexibility as a silicate-migration mechanism, after silicate envelopes first arise around chromite grains and then vanish into the surrounding magnesia by the suction of capillary force during the burning process.

Nanostructures/TiN layer/Al2O3 layer/TiN substrate configuration-based high-performance refractory metasurface solar absorber

Metasurface solar absorber serves as a kind of important component for green energy devices to convert solar electromagnetic waves into thermal energy. In this work, we design a new solar light absorber configuration that incorporates the titanium nitride substrate, aluminum oxide layer, titanium nitride layer, and the topmost refractory nanostructures. The metasurface absorber based on this configuration can achieve an average spectral absorption of over 91% and a total solar radiation absorption of 91.5% at ultra-wide wavelengths of 300–2500 nm. It is discovered that the excellent performance of the proposed metasurface absorber is attributed to the synergistic effects of surface plasmonic effect and Fabry–Pérot (FP) cavity resonance by comprehensive analysis of the simulated field distributions. Furthermore, the effect of geometrical parameter of the proposed configuration on absorber performance is studied, indicating the proposed configuration possesses a large fabrication tolerance. Moreover, the proposed configuration is not sensitive to the polarization direction and the angle of incident light. It is also found that the use of other refractory metal materials and other shapes as the topmost absorbent nanostructures also have good results with this configuration. This work can offer a universal platform for constructing and guiding the design of refractory metasurface solar absorbers.

Towards High-Quality Investment Casting of Ti-6Al-4V with Novel Calcium Zirconate Crucibles and Optimized Process Control

The investment casting of titanium and its alloys relies on a high resistance of the crucibles and shell molds in terms of temperature and reactivity. The availability of ceramic crucibles that offer sufficient resistance to the titanium melt enables vacuum induction melting (VIM). CaZrO3 prepared from a mixture of CaO and ZrO2 as a raw material for refractory ceramics shows a high corrosion resistance against metallic melts even under very high temperatures up to 1800 °C. Crucibles and shell molds of CaZrO3 were successfully produced and used in subsequent casting trials. This study is focused on the refractory crucibles suitable for casting Ti-6Al-4V (Ti-64) using a tilt casting machine. In order to evaluate the crucible reaction and, therefore, the quality of the castings, chemical analyses, investigations of the microstructures and hardness measurements were carried out. Careful control of the melting duration is mandatory to avoid crucible reactions that otherwise result in contamination of the cast with oxygen and zirconium. This was achieved by modified coil geometries. Under optimized casting conditions, the oxygen and zirconium impurity limits of ASTM B367-09 for titanium castings were met. Based on the correlations found, optimized casting parameters with regard to material quantity, coil geometry and heating power could be determined in order to provide guidance for a high-quality casting process with VIM.