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In the past few decades, a development of organic magnets with room-temperature strong ferromagnetism is challenged by the difficulty of creating three-dimensional (3D) long-range magnetic orderings in organic materials at a temperature higher than room temperature. Here, we report room-temperature ferrimagnetism of a tetragonal organic–inorganic hybrid Fe14Se16(tepa)III (tepa = tetraethylenepentamine), where III represents a coordination of a tepa molecule with a Fe3+ ion for an organic complex. The layered hybrid in a nanoplate-like shape is formed by periodic incorporation of tetragonal β-Fe3Se4 inorganic layers and organic spacing layers consisting of tepa and Fe3+. Fe14Se16(tepa)III shows a saturation magnetization MS of 7.2 emu g−1 at 300 K and a record-high Néel temperature TN (>560 K) in the organic magnets reported experimentally. A Mössbauer spectrum confirms a 3D long-range magnetic ordering of Fe2+ [S = 2 (71.4%)] and Fe3+ ions [S = 5/2 (21.7%) and 1/2 (4.0%)] in β-Fe3Se4 layers and organic spacing layers of Fe14Se16(tepa)III,9. First-principles calculations explain that the 3D long-range antiferromagnetic interactions between interlayer and intralayer irons result in the strong ferrimagnetism of Fe14Se16(tepa)III. This study unveils the possibility of tuning magnetic couplings of interlayer and intralayer high-spin Fe3+ and Fe2+ for enhancing the ferrimagnetism of layered hybrids and, thus, for future room-temperature magnetic/spintronic applications. [ABSTRACT FROM AUTHOR]

BiFeO3–BaTiO3 (BF–BT) is one of the lead-free piezoceramic materials with high Curie temperature (TC) and high polarization. Herein, the (Bi0.5Li0.5Ti)6+ group elements are introduced into the 0.75BiFeO3−0.25BaTiO3 (0.75BF–0.25BT) system to optimize comprehensive performances via optimizing the intrinsic piezoelectric contribution and the extrinsic piezoelectric contribution. For intrinsic piezoelectric contribution, the tetragonal phase ratio of the ceramics is increased. For extrinsic piezoelectric contribution, the grain structures and the domain structures of the ceramics are improved with a relaxor state in which small-sized domains and large-sized domains coexist. The best overall performances are obtained at x = 0.010 with piezoelectric constant d33 ∼ 130 pC/N at room temperature, d33 ∼ 231 pC/N at 313 °C, resistance ρ ∼ 1.49 × 106 Ω cm at 300 °C, and Curie temperature TC ∼ 632 °C that improved significantly. Moreover, when x = 0.010, the piezoelectric thermal stability is also significantly improved, with Δd33 being less than 15% before 200 °C and maintaining 60% of d33 at 400 °C. The present experiments provide a new strategy to investigate the origin of the enhanced piezoelectric response of BF–BT ceramics as well as their applications in the field of high-temperature lead-free piezoelectricity. [ABSTRACT FROM AUTHOR]

The 2D Bi2Te3 narrow bandgap semiconductor is an outstanding applicant for optoelectronics and thermoelectric devices. The doping of Se into Bi2Te3 makes metal-double chalcogenide more important. In the current investigation, the Se diffusion into the Bi2Te3 film by thermal annealing at different temperatures is probed through a temperature-dependent Raman study along with other characterizations. Upon annealing, the Se/Bi2Te3 films of ∼810 nm thickness resulted in significant changes to their structural, electronic, and optical behavior. The existence of a rhombohedral Bi2Te3 phase was confirmed by structural investigation. The improvement in crystallinity and decrease in lattice strain modified the optical behavior of the films. The morphology analysis showed a slight aggregation at the higher annealed stage. The uniform and homogeneous dispersal and the composition of elements in the film were verified through surface mapping and compositional analysis. The optical investigation revealed a drop in absorbance with increased transmittance. The direct optical bandgap increased from 0.53 ± 0.002 to 0.77 ± 0.002 eV, showing a blue shift. The non-linear refractive index decreased from 3.72 to 1.85 × 10−16 m2/W upon annealing. The temperature-dependent Raman analysis demonstrated a thermally induced significant vibrational change in the material with specific additional peaks at higher annealing. Such findings can be employed as a phase change material at very high temperatures. The obtained findings are very useful for optoelectronic applications. Surface wettability shows a reduction in hydrophilicity, thus inching toward a hydrophobic one with an increase in annealing temperatures. The enhancement in the photocurrent with the increment in the annealing temperature is more suitable for photovoltaic applications. [ABSTRACT FROM AUTHOR]

Temperature dependent bonding behavior plays a significant role in deciding properties of high temperature ceramics like boron carbide. However, few studies to date have addressed the physical properties of this class of materials with respect to their temperature dependent bonding nature. In addition, materials with the flexibility to accommodate variations in interatomic bonding and lattice vibrations over a wide range of temperatures are less known. In this work, temperature dependent structural analyses of carbon-rich boron carbide microflakes using in situ powder x-ray diffraction techniques (up to 1000 °C) supported by transmission electron microscopy measurements reveal that while most bonds in the rhombohedral structure increase in length with temperature; there is no change in certain bond lengths. However, there is an unusual decrease in length (∼1.03%) of the inter-cluster –C–(central boron)BC–C– without any polyhedral redistribution. This is accompanied by an increase in lattice vibrations without significant alteration to the crystal structure over the wide temperature range studied. Temperature dependent micro-Raman experiments further confirmed the above observations. The above bonding behavior could be directly correlated to the trends in reported results of high temperature conductivity via the model of hole hopping through specific atomic positions of the rhombohedral framework, thus opening the scope to investigate structure–property relationships in high temperature functional materials. [ABSTRACT FROM AUTHOR]

Constitutive models are essential for describing the mechanical behavior of materials under high temperatures and pressures, among which the Steinberg–Guinan (SG) model is widely adopted. Recent work has discovered a peculiar dual anomaly of compression-induced softening and heating-induced hardening in the elasticity of compressed vanadium [Phys. Rev. B 104, 134102 (2021)], which is beyond the capability of the SG model to describe. In this work, a modified SG elasticity constitutive model is proposed to embody such an anomalous behavior. Elemental vanadium is considered as an example to demonstrate the effectiveness of this improved model in describing the dual anomalies of elasticity. This new SG elasticity model can also be applied to other materials that present an irregular variation in the mechanical elasticity and are important to faithfully model and simulate the mechanical response of materials under extreme conditions. [ABSTRACT FROM AUTHOR]

Based on first-principles calculations, the current study deeply explores the thermoelectric properties of the Zintl compound SrPdTe. We found that the anharmonic vibration of Pd atoms plays an important role in the quartic anharmonic effect and the temperature dependence of the thermal conductivity. In the crystalline structure, Sr atoms form octahedra with eight surrounding Te atoms, while Pd atoms are located in the gaps between the octahedra. This structure makes the strong atomic mean square displacement of Pd atoms the main factor leading to the ultralow thermal conductivity. The study also reveals the effects of phonon frequency renormalization and four-phonon scattering on heat transfer performance. Even considering the spin–orbit coupling effect, multiple secondary valence band tops maintain the power factor of the material at high temperatures, providing a potential opportunity for achieving excellent thermoelectric performance. [ABSTRACT FROM AUTHOR]

Currently, the thermal quenching effect is still a pain point limiting the application of luminescent materials at high temperatures, and therefore it is of great significance to explore schemes with a well-defined mechanism to regulate the thermal quenching of phosphors. In this work, a controllable regulation of the energy level positions of the intervalence charge transfer bands was achieved by modifying the Sr/Ca ratio of Sr 1-x Ca x Nb 2 O 6 :0.005Pr3+. With the increase of x from 0.00 to 1.00, the IVCT energy level decreases from 4.03 eV to 3.96 eV, which leads to the easier transfer of 3P 0 electrons of Pr3+ to the 1D 2 energy level through the IVCT band during the heating process, and thus realizes the enhancement of the thermal stability of the 1D 2 emission, which is shown by the increase of the integrated emission intensity of 1D 2 at 573 K compared with that of 298 K from 22.87 % (x = 0) to 98.89 % (x = 1) gradually. In particular, CaNb 2 O 6 :0.005Pr3+ with the lowest IVCT energy level achieves a high degree of thermal stability, with the integrated emission intensity consistently maintained at 98.1%–103.6 % at 298K–573K. In addition, the phosphor's has potential for thermochromic and optical thermometry applications. This work shows the reliability of modulating the IVCT band energy level positions to realize the antithermal quenching of phosphors and its promising applications. A scheme to adjust the thermal quenching performance of Pr3+-doped niobate phosphor by using Pr3+-Nb5+ intervalence charge transfer band shift is proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

The paper describes the results of an experimental investigation into the bond behavior of fabric-reinforced cementitious matrix (FRCM)–masonry joints after exposure to high temperature. Single-lap direct shear tests (DS) were conducted on three different thermally conditioned FRCM composites applied to a clay brick masonry substrate. The FRCM studied comprised one layer of basalt, steel, and PBO (short for polypara-phenylene-benzo-bisthiazole) textile embedded within two inorganic matrices (cement based for the PBO FRCM composite and lime based for the basalt and steel FRCM composites). The joints were tested under residual conditions after exposure inside a thermal chamber for three hours at the target temperatures of 20°C, 100°C, 300°C, and 500°C. The thermal performances of the mortar matrices used in the FRCM systems were analyzed by X-ray diffractometry, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results show a peculiar bond behavior and failure mode for each composite. [ABSTRACT FROM AUTHOR]

This study investigates the acoustic performance of various porous materials at elevated temperatures, employing Constrained Gaussian Process Regression (CGPR) to model the relationship between specific airflow resistance and the absolute temperature. Experimental data on six fibrous material samples at 600°C are used to develop and compare CGPR models against conventional Power Law Regression (PLR) methods. The developed CGPR incorporates constraints such as boundedness, monotonicity and convexity/concavity derived from the evident relationships and prior knowledge of the specific airflow resistance versus temperature variations. The results of this study prove the outperformance of the developed CGPR over PLR methods in terms of data efficiency, predictive accuracy, uncertainty quantification, overfitting recovery and extrapolation capability. This comparative analysis outlines a significant improvement in the predictive accuracy of CGPR, achieving improved coefficient of determination values compared to PLR. CGPR also furnishes a direct strategy to quantify the uncertainty of predictions which is vital for applications at elevated temperatures. Additionally, CGPR offers valuable insights into sound absorption behaviour, highlighting its applicability in thermal acoustics and materials engineering. Prospective research avenues stem from this research as the developed CGPR technique has the potential to replace various modelling techniques in materials science and acoustic engineering applications. [ABSTRACT FROM AUTHOR]

Ceramic materials have the merits of an adjustable dielectric constant, high strength, high temperature resistance, and oxidation resistance, and are thus being used as the protection matrix for carbon series, metal oxides, and other wave-absorbing materials at high temperatures. Here, progress on high-temperature-resistant wave-absorbing ceramic materials is introduced through the aspects of their composition and structure. In addition, metamaterials used for such purposes, which are mainly produced through 3D printing, are also highlighted. The pros and cons of high-temperature-resistant electromagnetic wave absorbers based on ceramic materials are systematically analyzed, and possible development directions are proposed. This work may assist in the design and manufacture of a new generation of radars, ships, and aircraft. [ABSTRACT FROM AUTHOR]

Nano-sized quantum dots (QDs) have the potential for the application of stress sensing materials based on their pressure-sensitive photoluminescence (PL) properties, while the influence of a more realistic loading environment on the PL characteristics of QDs under a high-temperature environment remains to be further studied. Herein, we studied the PL response of CdTe QDs under repetitive loading–unloading conditions under high-temperature coupling to explore the stability of its high temperature stress sensing potential. The results show that the CdTe QDs with size of 3.2 nm can detect pressure in the range of 0–5.4 GPa, and the pressure sensitivity coefficient of PL emission peak energy ( E P L ) is about 0.054 eV/GPa. Moreover, the relationship between E P L and pressure of CdTe QDs is not sensitive to high temperature and repeated loading, which meets the stability requirements of the sensing function required for stress sensing materials under high temperature. However, the disappearance of PL intensity caused by spontaneous growth as well as the ligand instability of QDs induced by high temperature/high pressure affects the availability of E P L , which has a great influence on the application of CdTe QDs as high-temperature-resistant nano-stress sensing materials. The research provides the mechanical luminescence response mechanism of CdTe QDs under high-temperature/high-pressure coupling conditions, which provides experimental support for the design of high-temperature/high-pressure-resistant QD structures. [ABSTRACT FROM AUTHOR]

High temperature tribological automotive components are crucial parts of automotive to perform the required function. Aluminum alloys are known for their high strength-to-weight ratio, wear resistance, and corrosion resistance. This alloys have proved their worth in automotive application. Owing to the incorporation of different reinforcements in aluminum alloys, it allows to develop novel composites with desirable properties. However, the selection of suitable aluminum alloy for high temperature tribological application is crucial. This research article focused on selecting the most optimal material for usage in high temperature tribological applications. This study employed advanced multi-criteria decision making methodologies, specifically weights of criteria are calculated using entropy method and ranking of aluminum alloys have been done using technique for order preference by similarity to ideal solution (TOPSIS) and combined compromise solution (CoCoSo) method to investigate the complex process of material selection. By taking into account key criteria such as thermal degradation (TD), hardness (H), ultimate tensile strength (UTS), density (D), thermal conductivity (TC), melting point (MP), wear rate (WR), and corrosion resistance (CR), and three alternatives. The research aims to address the fundamental problems associated with material selection in the production of high temperature tribological automotive component. The study's findings highlight that among the three variants of 6xxx aluminum alloys (AA6061, AA6082, and AA6005) under examination, AA6082 emerges as the most optimal choice. The alternatives rank determined by the TOPSIS and CoCoSo methods, are identical when weighted using the entropy method. These findings provide valuable insights to manufacturers, equipping them with the knowledge needed to make informed decisions geared towards enhancing the performance and reliability of their high temperature tribological application of components. [ABSTRACT FROM AUTHOR]

As cracks can weaken the mechanical properties of rock and improve the rock-breaking efficiency, a new method of intentionally creating cracks in rocks by combining laser and a dry ice jet is proposed in this study. Shale, limestone, and sandstone were used as specimens in the experiments, and temperature fields on the rock surfaces were analyzed to evaluate the thermal effects. The crack distribution patterns and the thermal cracking characteristics were observed under different breaking conditions, and the micromorphology at the breaking point of each rock sample was analyzed. The results show that after laser pilot irradiation on the rock, the subsequent phase transition of the dry ice particles can lead to a temperature drop of 70 °C, 250 °C, and 300 °C on the surface of shale, limestone, and sandstone, respectively. More obvious cracks were observed on the shale and limestone surfaces, with the greatest increases of the crack length by 32.4% and 288.2%, respectively. Moreover, for shale and sandstone, the main component silicon dioxide can be transformed into a glassy molten material under high temperatures, while for limestone the main component known as calcium carbonate produces calcium oxide. The proposed method helps improve the rock-breaking efficiency and has the potential to be applied in mining and energy exploration. Highlights: A new rock-breaking method of combining laser and a dry ice jet was proposed. Huge temperature drops and enlarged crack lengths on the rock surface can be achieved by this method. Crack distribution patterns and thermal cracking characteristics were analyzed. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Exposure to elevated temperatures leads to the deterioration of the mechanical properties of cementitious materials. However, the inclusion of fibers can mitigate, to some extent, the negative effects of high temperatures on these materials. Specifically, polypropylene (PP) fibers, a synthetic fiber type, have been demonstrated to improve the performance of cement-based composites. Therefore, it is essential to investigate the impact of temperature on the behavior of fiber-reinforced mortar for its broader application in construction. This study explores the effects of varying PP fiber contents (0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1%) and different temperature exposures (25 °C, 200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C) on the performance of cement mortar. The experimental results show that elevated temperatures significantly degrade both the mechanical and thermal properties of fiber-reinforced mortar. As the temperature and fiber content increase, both the quality and thermal conductivity of the mortar decrease. Between 25 °C and 200 °C, the incorporation of PP fibers (ranging from 0% to 0.2%) significantly enhances the compressive and flexural strengths of the mortar. However, this improvement becomes less pronounced as the fiber content exceeds 0.2%. At temperatures above 200 °C, further increases in temperature, coupled with higher fiber contents, consistently lead to a reduction in the compressive and flexural strengths. Based on the principles of continuous damage mechanics (which describes the degradation and fracture of materials under loading) and the dual-parameter Weibull distribution theory, a constitutive model is proposed to describe the damage behavior of high-temperature PP-fiber-reinforced mortar under uniaxial compressive stress. [ABSTRACT FROM AUTHOR]

Reactive powder concrete (RPC) is widely used in ultra-high-rise buildings, hydropower stations, bridges, and other important infrastructures. To study the dynamic response and damage characteristics of RPC columns and frames considering coupled fire and explosions, an analytical model of RPC columns and frames with coupled fire and explosions was established by using ABAQUS (2021) finite element software. The dynamic response and damage degree of RPC columns under coupled fire and explosions were investigated to reveal the influence laws of parameters such as cross-section size, axial compression ratio, reinforcement rate, and fire duration on the dynamic response of RPC columns at high temperatures. The dynamic response of the frame structure was analyzed when the explosion load was applied to the bottom corner columns, side columns, and top beams, respectively. The results show that the fire severely weakened the blast resistance of RPC columns; the maximum mid-span deformation and residual deformation of RPC columns decreased with the increase in cross-section size and longitudinal bar reinforcement ratio and increased with the increase in fire duration and axial compression ratio. When the explosion load was applied to the corner columns of the bottom floor of the frame, the bottom corner columns were almost completely destroyed, and there was a significant risk of the structure collapsing. Based on the results of the data analysis, a method to enhance the explosion resistance of RC frame structures using RPC materials at high temperatures is proposed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Wuhan University of Science & Technology is the property of Wuhan University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The abrasive wear phenomenon at elevated temperatures is very common in industries where operations are performed under extreme conditions. The occurrence of abrasive wear at high temperatures is typically far more severe than that under room-temperature conditions. Industrial machine parts are much more prone to wear at extreme temperatures. Wear due to high-temperature abrasion leads to higher costs. Due to the risk of damaging machine parts and increased costs, it is significant to investigate materials that reverse this loss. It has been proven in previous studies that high-chromium white cast irons with multiple components, including vanadium, molybdenum, tungsten, and cobalt, called MWCIs, are among the most useful materials that can be selected as wear-resistant materials at high temperatures because of their dominant behavior against wear. In this study, three series of high-chromium multicomponent white cast irons (18Cr, 27Cr, and 35Cr MWCI) were used to test their abrasive wear resistance capability. A higher percentage of Cr leads to the precipitation of hard M7C3 carbides, which results in a higher carbide volume percentage (CVF) and hence higher hardness. However, the addition of excessive Cr and less C results in carbide refinement and a drop in hardness. The microstructure is primarily austenite. This study shows that, at an operating temperature of 1073 K, the 27CrMWCI performs the best as an abrasive wear-resistant material compared to 18CrMWCI and 35CrMWCI due to its (27CrMWCI's) higher CVF and hardness. [ABSTRACT FROM AUTHOR]

Thermocouples are crucial instruments for measuring the temperature of high-temperature components in aero-engines. However, traditional manufacturing methods lack the necessary flexibility. In this study, ITO and In 2 O 3 inks were prepared, and ITO/In 2 O 3 thermocouples were fabricated on an Al 2 O 3 substrate using inkjet printing technology. The wettability of the ink was assessed through contact angle measurements, while film characterization was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrical properties of the thermocouples were evaluated using both static and dynamic testing platforms. The resulting ITO/In 2 O 3 thermocouples exhibited favorable densities and demonstrated temperature resistance up to 1600 °C without a protective layer. The output voltage was 84.1562 mV, the average Seebeck coefficient reached 57.889 μV/°C, and the temperature drift was measured at 6.575 °C/h over a period of 6.5 h. [ABSTRACT FROM AUTHOR]

β-LiVOPO 4 has the advantages of high energy density, high voltage platform and low cost. It is a promising cathode material for lithium ion batteries. However, its poor magnification hinders the further development of the material. Here, aiming at the problem of poor rate performance of β-LiVOPO 4 , we successfully prepared β-LiVOPO 4 @C material by high temperature solid phase method using glucose as carbon source. The X-ray diffraction (XRD) results indicate that a small amount of α-LiVOPO 4 produced during the initial calcination may transform into β-LiVOPO 4 after the secondary heat treatment with the carbon source. Scanning electron microscopy (SEM) and pore size distribution results show that carbon coating makes the size of β-LiVOPO 4 particles smaller, which is more conducive to the transport of Li+. Raman spectroscopy analysis showed that the β-LiVOPO 4 @4%C material contained more p3 hybrid graphite carbon, which enhanced the electronic conductivity. The results of X-ray photoelectron spectroscopy (XPS) analysis showed that the content of V5+ in β-LiVOPO 4 @4%C increased after charging to 4.5 V, which confirmed that the charge-discharge reaction was more thorough and could provide more discharge specific capacity. In addition, the π plasmon peak of β-LiVOPO 4 @4%C becomes stronger, which improves its electron transport rate. The electrochemical test results show that the Li+ diffusion rate of β-LiVOPO 4 material coated with 4 % carbon is significantly improved, and it has good rate performance. It delivers a discharge capacity of 140.5 mAh g−1 at 0.1C and a discharge specific capacity of 80.5 mAh g−1 at 0.5C, indicating that it is expected to be used as a cathode material for advanced lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) has been verified to ameliorate the performance attenuation of cement-based materials exposed to high temperatures; however, its efficacy on cement-based materials containing recycled fine aggregates (RFAs) remains ambiguous. Therefore, this study assesses the macro/microperformance variations in mortar containing RFAs with diverse GO dosages (0~0.08%) after high-temperature exposure. The hydration products, pore structure, and microstructure of mortar containing RFAs and GO were analyzed using an X-ray diffractometer, mercury intrusion porosimetry, and scanning electron microscopy, respectively. The study finds that GO can reduce the mass loss rate of mortar exposed to high temperatures and enhance the residual compressive strength and flexural strength. The incorporation of 0.06% GO leads to a 10.4% increase in compressive strength and a 32.3% increase in the flexural strength of mortar containing 50% RFA after high-temperature exposure at 500 °C. Furthermore, the incorporation of GO refined the pore size and improved the densification of the interfacial transition zone (ITZ) of the mortar after high-temperature exposure. Taking into account the mechanical properties, water absorption, and microstructure of the mortar containing RFAs, a GO dosage of 0.04~0.06% could be recommended as the optimum engineering dosage. [ABSTRACT FROM AUTHOR]

Recently, spintronics and opto-spintronics lead the dominant role in the electronics applications. In our work we have fabricated ZnO-rGO based NFO heterostructure to study the A.C and D.C characteristics under the variation of optical power and external magnetic field. ZnO-rGO acts as a photo detector under the visible range and NFO acts as a ferro magnetic material with high Curie temperature. D.C transport has been carried out through I-V measurement under variable optical power with magnetic field. There, the transport property of our device can be tuned under the variation of optical power but this variation is not so much prominent under different magnetic field. Additionally, A.C transport carried out through impedance spectroscopy measurement. The graphical nature of impedance spectroscopy revels the non-Debye type dielectric relaxation in the low frequency region. Theses graphs are also fitted with proper RC combinations to expose the interface morphology under variable conditions. Our investigation on ZnO-rGO/NFO heterostructure shows a very interesting opto-spintronics effect through magnetically tuning of photo current. [ABSTRACT FROM AUTHOR]

Ocean-island basalts display a relatively large range in their oxygen isotopic composition (δ18O) compared to mid-ocean ridge basalts (MORB). The origin of these variations in δ18O—due to a combination of crustal contamination and/or mantle heterogeneity—is controversial. Kamaʻehuakanaloa (formerly Lōʻihi Seamount) is an active submarine Hawaiian pre-shield volcano that is last known to have erupted in 1996. Basalts from Kamaʻehu (for short) are derived from a distinctive 3He-rich deep mantle source within the Hawaiian plume, yet they commonly experience at least two types of shallow crustal contamination based on enrichments in seawater-derived Cl and 234U. Here, we present oxygen isotopic analyses of volcanic glasses (n  = 102 from 53 samples) and single olivine crystals (n  = 47 from eight samples) for tholeiitic (n  = 28), transitional (n  = 4), and alkalic (n  = 18) basalts, and three hawaiites from Kamaʻehu. The average δ18O values of both glass and olivine from the North Rift Zone and NE summit platform (~5.6‰ and 5.1‰, respectively) are higher (at >95% confidence) than those from the South Rift Zone and the SW summit platform (~5.3‰ and 4.9‰). The glass alkalic index (AI<0 is the switch from alkalic to tholeiitic lavas as the degree of mantle melting increases) and incompatible element enrichment (K2O/TiO2) increases with decreasing MgO and CaO/Al2O3. The northern Kamaʻehu glasses are more frequently alkalic (~68%), more enriched, and more differentiated than those from southern Kamaʻehu (~81% tholeiitic or transitional). Model eruption ages from 226Ra–230Th disequilibria suggest that the transition from alkalic to tholeiitic volcanism at Kamaʻehu was nearly complete by ~2 ka. The predominantly alkalic northern lavas likely record an earlier phase of the volcano's eruptive history that has since been covered by the more recent eruptions of tholeiitic basalts to the south. These observations suggest that melt flux from the mantle (recorded by the AI values and K2O/TiO2 ratios) regulates the crustal processing and δ18O variations of Kamaʻehu magmas. The mantle-controlled transition from alkalic to tholeiitic volcanism at Kamaʻehu led to the more frequent supply of larger magma batches produced by higher degrees of mantle melting, establishment of an active shallow hydrothermal system for high-temperature alteration of the volcanic edifice, and a decreasing extent of clinopyroxene fractionation. The average δ18O values of glass (~5.4‰) and olivine (~5.0‰) from Kamaʻehu—similar to the most depleted MORB—represent the best estimate for mantle-derived magma at this volcano. The higher average δ18O values of the glass and olivine from northern Kamaʻehu result from assimilation of volcanic edifice that was altered by seawater-rock interaction at low temperature, whereas the lower δ18O values from southern Kamaʻehu result from assimilation of such materials altered at high temperature. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High temperature structural materials are essential for the proper function of ultra-supercritical power generation devices. The natural reductions in strength and elongation of the material at high temperatures of operation (from 600 to 750 °C) reduce the service life of the generator. In this research, a novel alumina-forming austenitic (AFA) stainless alloy was produced and studied as a promising option for such devices. After the design and production of the novel AFA alloy, detailed mechanical tests were conducted at elevated temperatures. The evolution of the fracture morphology, microstructure, and phase transformation was evaluated at different temperatures. According to an analysis of the microstructure, the strengthening mechanism of the alloy was a combination of solution strengthening and dislocation strengthening. Through dynamic recovery, the density of the dislocations decreased and the degree of work-hardening reduced, leading to a decrease in the strength with an increase in the temperature. The segregation of Fe and Cr at the grain boundary made the grain boundary brittle and caused ductility reduction. The electron backscatter diffraction results also showed reductions of the ratio of low-angle grain boundaries and the mean number of geometrically necessary dislocations. However, this novel AFA kept a high tensile strength and a large elongation at 750 °C, which confirmed it as a good option for ultra-supercritical power generation devices. [ABSTRACT FROM AUTHOR]

The high-temperature wear behavior of a Haynes 282® superalloy was studied at 625 °C in pin-on-roll sliding tests with a load of 68 N for 7.5 km using pins of the alloy in heat-treated (T) and wrought (W) conditions. Specific wear rate plots as a function of the sliding distance indicate that wear was more significant for up to 3.8 km for heat-treated specimens (T); however, wear of the alloys in both metallurgical conditions gave similar values, which did not increase from 5.0 km onwards. Characterization of the wear mechanisms suggests that metallic wear was present, expressed as the plastic deformation at the surface and subsurface regions of the alloys in both conditions. Oxidational wear was also found, which was more important for the W alloy. Nevertheless, the mixture of oxides and metallic particles favored the formation of tribofilms that reduced friction and prevented further wear. Tribofilms were also developed on the surface of the counter rolls, and particles from them were transferred to the surface of the nickel alloy pins by adhesion. [ABSTRACT FROM AUTHOR]

Polymer derived ceramics (PDCs) are an outstanding class of hightemperature matrix materials due to their excellent mechanical and chemical stability. In particular, polymeric precursors of silicon oxycarbide (SiOC) are of interest. The formation and phase development of an SiOC network is dictated by a range of processing parameters including temperatures, atmospheres, and molecular makeup. This study analyzed the effect of cure path and environment on the polymeric matrix of two siloxane preceramic polymers. The processability and polymerization behavior was explored by DSC and FTIR. The ceramization process and high temperature stability is analyzed after undergoing pyrolysis. This work demonstrates straightforward preceramic processing with traditional polymer techniques and contributes to the understanding of next generation polymer-derived ceramics for hypersonic applications. The goal of this research is to further the understanding of preceramic polymer cure protocols towards the development of high temperature hypersonic materials. [ABSTRACT FROM AUTHOR]

The editorial discusses the importance of mechanical and structural performance in ensuring societal safety, highlighting recent advancements in construction engineering. The Special Issue features 15 research papers covering topics such as structural damage detection, reinforced concrete, and non-destructive testing methods. Authors from various countries contributed to this issue, providing valuable insights that aim to inspire further innovations in the fields of structural and materials engineering. [Extracted from the article]

The measurement of mechanical properties of high-temperature resistant materials at high temperatures is particularly critical, and laser ultrasonic non-destructive testing technology is a prospective approach for measuring mechanical properties in high-temperature environments. Laser ultrasonic propagation models are constructed by finite element analysis, which reveals the effects of different excitation mechanisms on acoustic velocity measurements. It is found that the shear wave in the main propagation direction is hardly detected, and the distinction between shear waves and surface waves in the time domain signal is difficult. Based on the conclusions, the relationships between surface waves, longitudinal waves, and mechanical properties of materials are established by theoretical derivation. According to the propagation characteristics of surface waves and longitudinal waves, the eccentricity detection scheme of the same side and the concentricity detection scheme of the opposite side are, respectively, designed. The velocities of surface waves and longitudinal waves are measured, considering the thermal expansion coefficient and density changes with temperature. The mechanical properties of materials at different temperatures (25–1000 °C) are successfully calculated, and the experimental results are well in accordance with the reference values. It gives a reliable basis for efficient measurement of mechanical properties of materials at high temperatures. [ABSTRACT FROM AUTHOR]

Using plasma as an energy source in thermal spraying allows the processing of feedstock materials with high melting temperatures. In plasma spraying, hydrogen or nitrogen is commonly injected into the argon plasma, which increases the specific enthalpy and thermal conductivity. The objective of this study is to improve the understanding of this process through numerical simulation and to investigate the impact on the plasma properties. A comprehensive modelling approach for the electrodes in the three‐cathode plasma generator is built upon the previous work of the authors. The plasma is described as an electromagnetically reactive fluid in local thermodynamic equilibrium using temperature‐dependent thermodynamic and transport properties. The increase of flow temperature and velocity as well as the temperature distribution at the electrodes can be successfully simulated. The simulation model could accelerate parameter development for new coating systems in the future. This study completes the simulation model for multi‐arc plasma spraying using binary gas mixtures. [ABSTRACT FROM AUTHOR]

The hot corrosion behavior of Cr3C2–25NiCr composite coatings reinforced with nano yttria stabilized zirconia (YSZ) was evaluated under actual boiler conditions in a thermal power plant at 850 °C with cyclic thermal loading. The nano YSZ content was varied between 5 and 10 wt%, and the coatings were applied using the high-velocity oxy-fuel (HVOF) method. A comparative analysis of the impact of varying nano YSZ content on hot corrosion performance was conducted through weight change measurements, while corrosion products were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and cross-sectional analysis. Results indicated that increasing nano YSZ content improved the corrosion resistance of the coatings at high temperatures in the boiler environment, with lower weight gain and the formation of protective oxide scales. Higher nano YSZ content in the coating matrix led to a decrease in corrosion rates during the hot corrosion tests. The corrosion rates for the 5 wt% and 10 wt% YSZ–Cr3C2–25NiCr coated specimens were 4.82 mpy and 3.45 mpy, respectively, reflecting reductions in corrosion rates of 80.79% and 89.26%. The addition of YSZ significantly decreased the corrosion rate, with further reductions observed as the YSZ content in the Cr3C2–25NiCr coating increased. XRD analysis confirmed the presence of Ni, Cr2O3, Cr3C2 and ZrO2–Y2O3 phases, indicating that YSZ particles remained in the coating matrix after exposure. [ABSTRACT FROM AUTHOR]

Lithium-rich layered oxides represent a promising class of cathode materials for high-energy lithium-ion batteries. However, their application is hindered by suboptimal rate performance and cycling stability, particularly at elevated temperatures. This study focuses on enhancing the utility of lithium-rich cathodes in lithium-ion batteries by doping a 0.4Li2MnO3·0.6LiMn1/3Ni1/3Co1/3O2 composite with F and Mg. At ambient temperature (25 °C), the capacity retention after 200 cycles increased from 75.2% for the pristine cathode to 85.1% and 93.3% for the cathodes modified with F and Mg, respectively. At an elevated temperature of 55 °C, the pristine cathode exhibited marked capacity degradation, retaining only 61.6% after 100 cycles. In contrast, the F- and Mg-modified cathodes demonstrated enhanced durability, with capacity retentions of 81.8% and 85.6%, respectively. Moreover, voltage fading upon high-temperature cycling was mitigated, with the pristine cathode exhibiting a rapid decay rate of 1.97 mV per cycle, compared to the decay rates of 1.34 and 1.23 mV per cycle for the F- and Mg-modified samples over 50 cycles, respectively. For practical applications, the Mg-modified cathodes, which exhibited superior high-temperature performance, were assembled into solid-state batteries. These batteries demonstrated discharge capacities of 183 and 155 mAh g–1 at 2–4.8 V and 2–4.5 V, respectively, when tested at 55 °C. [ABSTRACT FROM AUTHOR]

Hydrogen storage materials are very critical for hydrogen energy utilization. Cubic Mg 2 XH 6 (X = Mn, Fe, Co, Ni) hydrogen storage materials are investigated by first principles calculation. The structural stability are confirmed by complex consideration of phonon spectrum, formation energies and elastic constants. They are brittle and hard materials with high temperature applicable potential. Mg 2 MnH 6 and Mg 2 CoH 6 are magnetic compounds while Mg 2 FeH 6 and Mg 2 NiH 6 are non-magnetic materials. Mg 2 MnH 6 and Mg 2 FeH 6 are semiconductors with bandgap of 1.867 eV and 3.318 eV, respectively, indicating they are applicable in optoelectronic field, while Mg 2 CoH 6 and Mg 2 NiH 6 are metallic in energy band structure. They are all ionic compounds which are confirmed by Cauchy pressure, electronic density difference and electronic localization function. Their hydrogen storage capacity are all over 5.2 wt%, which are favorable in practical use. And the moderate desorption temperature of 328.9 K of Mg 2 MnH 6 suggests it is a promising candidate for hydrogen storage. [ABSTRACT FROM AUTHOR]

Utilizing the electrical resonance method, matrices encompassing elastic, piezoelectric, and dielectric properties were calculated for 0.36BiScO 3 -0.64PbTiO 3 (BSPT) ceramics. The design parameters for the BSPT/epoxy 2-2 composite material were meticulously elucidated through simulations conducted via COMSOL software. Characterization outcomes unveil that the synthesized composite material exhibits diminished acoustic impedance and heightened electromechanical coupling in comparison to its piezoelectric ceramic counterparts. Subsequent to the design and fabrication of ultrasonic transducers employing both BSPT ceramics and BSPT/epoxy 2-2 composite material, a thorough investigation into their electrical and acoustic attributes ensued at ambient temperature and 200 °C. Test results manifest that the BSPT/epoxy 2-2 composite high temperature ultrasonic transducer (CHTUT) demonstrates a center frequency and bandwidth of 4.52 MHz and 54.71%, respectively, at room temperature. While, at 200 °C, these parameters are 3.54 MHz and 80.79%. The HTUT, under parallel scrutiny, exhibits a center frequency and bandwidth of 4.65 MHz and 34.23% at room temperature, respectively, and 4.52 MHz and 29.65% at 200 °C. These findings prove the robust ultrasonic performance of the CHTUT, even under elevated temperatures, with the BSPT ceramic based counterpart demonstrating superior temperature stability. Furthermore, the results of an imaging experiment involving steel step blocks at both room temperature and 200 °C align consistently with the acoustic test outcomes. [ABSTRACT FROM AUTHOR]

At present, requirements for aircraft gas turbine engines, including their fuel efficiency, noise level, and weight, are becoming more and more stringent. One key factor capable of ensuring that these requirements are met is materials of engines, especially those in their hot part, which allow their working temperature and efficiency to be raised. Currently, multicomponent nickel-based alloys with a tailored structure are used in aircraft engine turbines, but their temperature capabilities are almost exhausted and limited by a temperature of ~1150°C on the alloy surface. In view of this, there is ongoing effort to design new alloys and coatings capable of operating at higher temperatures in aircraft engine turbines. Here we present our results on the structure and phase composition of heat-resistant coatings based on the Y–Al–O system, studied by scanning electron microscopy, X-ray diffraction, and in situ synchrotron X-ray diffraction during heating. Y–Al–O coatings were grown on Inconel 718 alloy and molybdenum substrates by cathodic arc deposition with the use of two single-component cathodes, from yttrium and aluminum, in an oxygen + argon mixture. It was shown that, after deposition in the reaction gases, the Y–Al–O coatings had an amorphous structure. Subsequent heating in air led to their crystallization and the formation of Y–Al–O mixed oxides with a dense structure. We studied phase transformations of the coatings during heating to 1300°C and holding at this temperature for 1 h in air. [ABSTRACT FROM AUTHOR]

The high-temperature superconducting cuprates host unidirectional spin- and charge-density-wave orders that can intertwine with superconductivity in nontrivial ways. While the charge components of these stripes have now been observed in nearly all cuprate families, their detailed evolution with doping varies across different materials and at high and low temperatures. We address this problem using nonperturbative determinant quantum Monte Carlo calculations for the three-band Hubbard model. Using an efficient implementation, we can resolve the model's fluctuating spin and charge modulations and map their evolution as a function of the charge transfer energy and doping. We find that the incommensurability of the charge modulations is decoupled from the spin modulations and decreases with hole doping, consistent with experimental measurements at high temperatures. These findings support the proposal that the high-temperature charge correlations are distinct from the intertwined stripe order observed at low-temperature and in the single-band Hubbard model. [ABSTRACT FROM AUTHOR]

The homogeneous dispersion of multi‐walled carbon nanotubes (MWCNTs) in a polymer matrix significantly affects the overall properties of composites. In this study, MWCNTs/epoxy (EP) composites were prepared using DeoxyriboNucleic acid (DNA) as a dispersant. The MWCNTs were uniformly dispersed in a phenalkamine curing agent and crosslinked with an epoxy resin matrix. The non‐covalent functionalization of DNA‐dispersed MWCNTs was confirmed by characterizing both the pristine and DNA‐modified MWCNTs. Additionally, the dispersion state and stability of MWCNTs in the curing agent solution were evaluated. Tensile strength and single‐lap‐shear (SLS) were employed to assess the mechanical properties of the composites. The results indicated that the DNA‐dispersed MWCNTs composites exhibited superior strength and toughness, with tensile and shear strengths of 46.81 and 19.64 MPa, respectively, at optimal ratios. These values represent increases of 68.38% and 50.96% compared to pure EP. Dynamic mechanical thermal analysis (DMTA) revealed that the energy storage modulus of DNA‐dispersed MWCNTs/EP composites increased to 2722 MPa, a 24.7% enhancement over pure EP. Furthermore, the thermal properties of the composites were thoroughly investigated. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that the initial decomposition temperature of the DNA‐assisted dispersed composites rose to 330°C. The macromolecular relaxation of the EP materials occurred at higher temperatures, leading to an increased glass transition temperature. Highlights: DNA was used to disperse MWCNTs in phenalkamine curing agent.MWCNTs/EP composites were made by crosslinking DNA‐dispersed MWCNTs with epoxy resin.DNA‐dispersed MWCNTs boosted tensile and lap shear strength.Thermal properties improved due to DNA‐dispersed MWCNTs, and increased the energy storage modulus of the composite. [ABSTRACT FROM AUTHOR]

C/C composite was successfully brazed with TiZrHfTa/Ni or ZrHfNbTa/Ni composite interlayers using spark plasma sintering. The influence of different interlayers and joining parameters on the joint morphology, shear strength at room temperature and 1000 °C was investigated. For both composite interlayers, the C/C joints obtained at 1800 °C for 30 min consisted of a single high entropy cermet structure, with a near equimolar high entropy carbide hard phase and a near pure Ni binder phase. However, the use of different composite interlayers resulted in differences in the elastic modulus and hardness of the formed high entropy carbide phase. The maximum shear strengths of the obtained C/C composite joints using TiZrHfTa/Ni and ZrHfNbTa/Ni interlayers at room temperature were close, with value of 37.49 ± 1.44 MPa and 38.95 ± 1.26 MPa, respectively. Because (Zr-Hf-Nb-Ta)C had better high-temperature stability than (Ti-Zr-Hf-Ta)C, the obtained C/C-ZrHfNbTa/Ni-C/C joint exhibited a higher shear strength of 28.54 ± 1.71 MPa at 1000 °C. After shear testing at both room temperature and 1000 °C, fractures in all joints predominantly occurred within the C/C composite near the reaction layer, indicating a substrate failure mode. The use of composite interlayers resulted in C/C composite joints with excellent shear strength, primarily due to the in-situ synthesized high entropy cermet reaction layer, which provided superior strength and toughness. Additionally, the laser-textured pattern on the C/C composite surface formed numerous interlocking structures at the joint interface, further enhancing the joints' shear strength. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) magnetic materials with high critical temperatures (TC) and robust magnetic anisotropy energies (MAE) hold significant potential for spintronic applications. However, most of 2D magnetic materials are derived from the van der Waals (vdW) layered bulks, which greatly limits the synthesis of 2D magnetic materials. Here, 2D M3B4 (M = Cr, Mn, and Fe; B = Boron), derived from hexagonal and orthorhombic M3AlB4 phases by selectively etching Al layers, was studied for its structural stability, electronic structure, and magnetic properties. By utilizing ab initio calculations and Monte Carlo simulations, we found that the orthorhombic Cr3B4 shows ferromagnetic (FM) metal and possesses an in-plane magnetic easy axis, while the remaining hexagonal and orthorhombic M3B4 structures exhibit antiferromagnetic (AFM) metals with a magnetic easy axis which is perpendicular to the two-dimensional plane. The critical temperatures of these 2D M3B4 structures are found to be above the 130 K. Notably, the ort-Mn3B4 possesses highest TC (~600 K) and strongest MAE (~220 µeV/atom) among these borides-based 2D magnetic materials. Our findings reveal that the 2D M3B4 compounds exhibit much better resistance to deformation compared to M2B2 MBenes and other 2D magnetic materials. The combination of high critical temperature, robust MAE, and excellent mechanical properties makes 2D Mn3B4 monolayer exhibits a favorable potential for spintronic applications. Our research also sheds light on the magnetic coupling mechanism of 2D M3B4, providing valuable insights into its fundamental characteristics. IMPACT STATEMENT: Two-dimensional magnetic hexagonal and orthorhombic M3B4 compounds with significant stiffness to preserve their magnetic properties were discovered using DFT calculations and MC simulations. [ABSTRACT FROM AUTHOR]

This work focuses on the fabrication and evaluation of a passive wireless sensor for the monitoring of the temperature and corrosion of a metal material at high temperatures. An inductor–capacitor (LC) resonator sensor was fabricated through the screen printing of Ag-based inks on dense polycrystalline Al2O3 substrates. The LC design was modeled using the ANSYS HFSS modeling package, with the LC passive wireless sensors operating at frequencies from 70 to 100 MHz. The wireless response of the LC was interrogated and received by a radio frequency signal generator and spectrum analyzer at temperatures from 50 to 800 °C in real time. The corrosion kinetics of the Cu 110 was characterized through thermogravimetric (TGA) analysis and microscopy images, and the oxide thickness growth was then correlated to the wireless sensor signal under isothermal conditions at 800 °C. The results showed that the wireless signal was consistent with the corrosion kinetics and temperature, indicating that these two characteristics can be further deconvoluted in the future. In addition, the sensor also showed a magnitude- and frequency-dependent response to crack/spallation events in the oxide corrosion layer, permitting the in situ wireless identification of these catastrophic events on the metal surface at high temperatures. [ABSTRACT FROM AUTHOR]

Degradation of coatings and structural materials due to high temperature corrosion in the presence of molten salt environment is a major concern for critical infrastructure applications to meet its commercial viability. The choice of high value coatings and structural (construction parts) materials comes with challenges, and therefore data centric approach may accelerate change in discovery and data practices. This research aims to use machine learning (ML) approach to estimate corrosion rates of materials when operated at high temperatures conditions (e.g., nuclear, geothermal, oxidation (dry/wet), solar applications) but geared towards nuclear thermochemical cycles. Published data related to materials (structural and coatings materials), their composition and manufacturing, including corrosion environment were gathered and analysed. Analysis demonstrated that random forest regression model is highly precise compared to other models. Assessment indicates that very limited sets of materials are likely to survive high temperature corrosive environment for extended period of exposure. While a higher quality and larger dataset are required to accurately predict the corrosion rate, the findings demonstrated the value of ML's regression and data mining capabilities for corrosion data analysis. With the research gap in material selection strategies, proposed research will be critical to advancing data analytics approach exploiting their properties for high temperature corrosion applications. [ABSTRACT FROM AUTHOR]

The need for advanced materials that can meet application requirements at ultra-high temperatures in oxidizing environments is an area of active research. One challenge facing the high temperature materials community is the ability to conduct controlled ultra-high temperature oxidation tests with minimal to no contamination or reaction with the chamber. A unique resistive heating system (RHS) capable of achieving ultra-high temperatures (> 1700 °C) to enable such experimentation is described. A concern of such a system is the potential presence of thermal gradients in directions not reflective of actual material applications, e.g., the hottest region being in the center of the sample. Experimental results from the oxidation of ZrB2 specimens at nominal temperatures of 1500°, 1700° and 1800 °C in low pO2 (0.1–1% O2 in Ar) environments are presented. Specimen thermal gradients generated during oxidation were evaluated using finite element analysis models. Thermal gradients on the order of the uncertainty in temperature measurements were calculated, confirming the RHS suitability for conducting ultra-high temperature oxidation exposures on ultra-high temperature ceramics. [ABSTRACT FROM AUTHOR]

Textiles are integral to human life, spanning uses from clothing and home decor to industrial applications and economic contributions. Garments and accessories showcase personal expression, while home textiles enhance living spaces and provide comfort. The textile industry also offers employment to millions globally, with traditional textiles influencing cultural, social, and economic aspects of life. However, specific conditions demand specialized textiles. In industries like metal and chemical production, textiles with high heat resistance, flame retardancy, or chemical protection require advanced engineering and manufacturing technologies. As living conditions evolve, so do the demands on textiles. Beyond current features such as antibacterial properties, resistance to temperature extremes, and durability, future textiles will incorporate advanced functionalities. Innovations may include energy self-generation, integration with the Internet of Things (IoT), and sensor-based health monitoring to continuously track human well-being. This article explores recent advancements in nanotechnology applications in textiles and provides a roadmap for the future, emphasizing how technology is reshaping this essential industry to meet emerging needs. [ABSTRACT FROM AUTHOR]

Walking beam reheating furnaces in hot strip mills use water-cooled skid beams for moving the slabs inside the furnace. These skids were found to fail frequently with water leaks. Failure of these skids results in process interruption and production loss. Detailed failure analysis was carried out to investigate the mechanism and reasons for such failure. The scale deposits were collected from the inside of the skid pipes and analyzed by XRF. The XRF results inferred the oxidized layer to be primarily of iron oxide with some percentage of water-based deposits (oxides of Ca, Mg, and Si). The skid beam samples were collected at the affected and unaffected regions and were analyzed using optical microscopy and hardness testing. The microstructures of the unaffected skid samples revealed a ferritic-lamellar pearlitic structure, whereas at the affected region the microstructure showed spheroidization of carbide particles and degenerated pearlite. This change in microstructure indicated that failure resulted from prolonged high-temperature exposure of the skid beams. The poor strength of the skid pipe refractory insulation system has led to the exposure of the skids to high temperatures and resulted in the early rupture of the skid pipe. [ABSTRACT FROM AUTHOR]

Calcium silicate–based materials have been a long-time favourite in thermal insulation applications. This work emphasises synthesising calcium silicate–based thermal insulating material via solid-state reaction using silica, calcium carbonate and fly ash as binding material. The calcium silicate formulations were mixed into a ratio of 1:1:1 (CaO:SiO2:FA) and sintered at temperatures 800–1100°C for 2 h. The developed tailored powder and the sample with calcium silicate formulations were characterised by X-ray diffraction, IR, thermagravimetric analysis, scanning electron microscopy (SEM)-EDS and thermophysical properties (thermal diffusivity, heat capacity per unit volume and thermal conductivity). The synthesised samples are composed mainly of calcium silicate phases, that is, wollastonite with minor larnite and rankinite. The microstructure was evaluated by SEM. It was found that the developed calcium silicate material reached low thermal conductivity values, that is, 0.29 and 0.42 W/mK (for 2P1000 and 2P1100, respectively). The thermal constant analysis of the material shows the stability of the material at high temperatures. Thus, the present results suggest that in-situ calcium silicate–based material prepared is a good thermal insulation ceramic material. [ABSTRACT FROM AUTHOR]

VDM alloy (AM) 699 XA (AM-XA) produced by laser powder bed fusion (LPBF) was subjected to steam oxidation at different high temperatures. Initial studies on mass gain of AM-XA at 650 °C after 500 hours revealed insignificant changes. Typical to high temperatures, a wide range of oxides were obtained at 750 and 950 °C associated with mass gain. To fully understand AM-XA material behavior at high temperatures, hot-rolled 699 XA (HR-XA) was also fabricated and tested under similar conditions. At 750 °C, HR-XA showed a higher mass gain in comparison with AM-XA, whereas at 950 °C mass gain of AM-XA overtook HR-XA. This anomalous behavior was related mostly to carbide formation. In-depth anomalous behavior of AM-XA is explained by investigating the microstructure and phase composition of the oxidation products formed. [ABSTRACT FROM AUTHOR]

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This research aims to establish a systematic framework for parametric identification of materials undergoing high temperatures and high strain rates. While advanced testing equipment, such as the Gleeble physical simulator, can produce controlled measurements of specimens under various conditions, significant challenges remain in determining the parameters of constitutive relations. Temperature gradients inevitably arise during Gleeble testing, leading to nonuniform strain distribution caused by complex thermal–mechanical coupling. Although finite element analysis of Gleeble testing can be performed, such simulations are computationally expensive, making brute-force optimization to minimize the difference between experimental data and finite element simulation across the parametric space infeasible. Furthermore, since the related constitutive relations are semi-empirical in nature, the ground truth of the constitutive parameters is generally unknown. In this context, a single-objective optimization based on a number of testing conditions may yield biased results or become trapped in local minima. In this research, we employ finite element analysis simulating Gleeble operation as the foundation, leveraging a suite of computational intelligence tools to address these challenges. We first develop a multi-response Gaussian process surrogate model, trained using a relatively small amount of finite element data, to rapidly emulate the forward analysis. We then implement a multi-objective optimization approach using simulated annealing to individually minimize the differences between experimental results and emulations under various testing conditions. AISI 9310 steel and the Johnson–Cook model are adopted for methodological demonstration. The development of the finite element model, Gaussian process surrogate model, and inverse optimization is detailed, and the results obtained are discussed. This framework can be extended to the parametric identification of other materials and heat treatment conditions using Gleeble testing. [ABSTRACT FROM AUTHOR]