High Temperature Conditions Research Articles

Studies on the retarded recrystallization of tungsten in CIMPLE-PSI exposed under very-high target temperature and long He+-fluence

Abstract Experiments are carried out in CIMPLE-PSI, to understand the recrystallization behavior of tungsten (W) exposed under very-high target temperature and ITER relevant long He+-fluence. The effect of helium bubbles on possible retardation of the recrystallization process is also studied. W samples are simultaneously exposed under He plasma and annealed by the plasma heat-load, in contrast to previously reported experiments in literature, which were carried out sequentially. Exposed samples are characterized by field emission scanning electron microscopy (FESEM), Vickers surface micro-hardness, nano-hardness and electron backscattered diffraction (EBSD). It is observed that the sample exposed to plasma under the highest temperature (1866 K) suffered acute retarded grain growth. This also contained small, unrecovered grains on the exposed surface. FESEM imaging of the cross-sections confirm relatively smaller helium bubbles still form even at the very high temperature conditions, which can impede the grain growth locally, whenever they are forming right on the grain boundaries. This results in an inhomogeneous mixture of surface grains with sizes from few micrometer to few tens of micrometer. EBSD estimates that the plasma exposed surface was only 34% recrystallized. The second sample exposed at a lower temperature (1699 K) but for three times higher fluence (ion fluence: 1.19×1027 m-2) was almost fully recrystallized, which shows retardation diminishes very fast with the duration of the exposure. Hardness measurements were undertaken to understand the variation with plasma exposure/annealing temperature and the extent of recrystallization, with three different probing length scales, spanning from few hundreds of nanometer to several micrometers. Both helium plasma exposed W samples are observed to undergo retarded softening up to a depth of few hundred nanometers from the surface, compared to when the metal may be recrystallized by simple heating, without any plasma exposure.

Phase Behavior and Rational Development Mode of a Fractured Gas Condensate Reservoir with High Pressure and Temperature: A Case Study of the Bozi 3 Block

The Bozi 3 reservoir is an ultra-deep condensate reservoir (−7800 m) with a high temperature (138.24 °C) and high pressure (104.78 MPa), leading to complex phase behaviors. Few PVT studies could be referred in the literature to meet such high temperature and pressure conditions. Furthermore, it is questionable regarding the applicability of existing condensate production techniques to such a high temperature and pressure reservoir. This study first characterized the phase behavior via PVT experiments and EOS tuning. The operating conditions were then optimized through reservoir numerical simulation. Results showed that: (1) the critical condensate temperature and pressure of Bozi 3 condensate gas were 326.24 °C and 43.83 MPa, respectively; (2) four gases (methane, recycled dry gas, carbon dioxide, and nitrogen) were analyzed, and methane was identified as the optimal injection gas; (3) gas injection started when the production began to fall and achieved higher recovery than gas injection started when the pressure fell below the dew-point pressure; (4) simultaneous injection of methane at both the upper and lower parts of the reservoir can effectively produce condensate oil over the entire block. This scheme achieved 8690.43 m3 more oil production and 2.75% higher recovery factor in comparison with depletion production.

Color/Transparent Bi‐Customizable Solar Antifogging Nanofilms

AbstractAlmost all reported solar anti‐/defogging surfaces are black and opaque. However, aesthetics and transparency are preferred to enhance security, privacy, and visual experience without sacrificing antifogging in some practical scenarios, such as automotive windshields, architectural glass facades, and sports goggles. Herein, a color and transparency bi‐customizable solar antifogging heterostructure nanofilms is reported, which only consists of a Ti–TiOx layer for partial visible light transmission and a narrow bandgap Ti2O3 layer for broadband sunlight absorption. By precisely controlling each monolayer thickness, various vibrant structural colors (covering yellow/green/purple/blue) through interference effects, along with tunable visible light transparency (from 0% to 30%), and broadband solar absorption (up to 90%) are obtained, providing personalized options for various applications. Simultaneously, the nanofilms exhibit remarkable photothermal performance (110.3 °C under 1 kW m−2 irradiation) compared to blank samples, demonstrating sustained and superior defogging (3.5‐fold improvement) and antifogging capabilities, even in extremely cold (–20 °C) or high temperature and high humidity (50 °C, 100%) conditions. Importantly, the nanofilms are just 174 nm thick, and can be easily upgraded and scalable fabricated by sputtering on various rigid, flexible and portable substrates, such as glass, metals, textiles, plastics, enabling a wide range of direct applications.

Estimation of Genetic Parameters in Bread Wheat (Triticum aestivum L.) Genotypes Evaluated Under High Temperature Yield Trial in Ethiopia

The study was carried out to estimate genetic parameters of 49 bread wheat genotypes and standard check evaluated at Kulumsa and Melkasa using alpha lattice design with two replications. The analysis of variance result showed highly significant differences among the genotypes for all traits (P< 0.001), implying the presence of considerable genetic variability for these traits. Out of 50 genotypes, four genotypes such as EBW2113062, EBW2113039, EBW2113037 and EBW2113056 were the top yielding genotypes across the locations. Furthermore, 30 of the 50 genotypes gave grain yield above grand mean whereas 14 genotypes had grain yield above the check, Dursa(1295.05kg/ha). In the other word, about 60% of genotypes were with mean grain yield above the overall mean and 30% of them provided mean grain yield above the check, Dursa, variety. High and moderate heritability estimates were found for most of traits showing that the variation observed was mainly under genetic control. The highest PCV and GCV values were observed for grain yield at both locations indicating better opportunity for improvement in this trait via selection. The phenotypic coefficient of variation (PCV) was generally higher than the genotypic coefficient of variation (GCV) for all characters at both locations. The difference between PCV and GCV was large in TKW followed by PHT and Grain yield indicating that these traits are influenced by the environment. However, differences between them were small for most of the traits indicating low effect of environment on the expression of characters at both locations. The genotypic correlations between grain yield with thousand kernel weights and hectoliter weight were highly significant showing their important contribution to grain yield. Therefore, the identified genotypes with better performance could be utilized in advanced bread wheat yield trial targeted for high temperature condition in the country.

Coordinatively Unsaturated Co Single-Atom Catalysts Enhance the Performance of Lithium-Sulfur Batteries by Triggering Strong d-p Orbital Hybridization.

The catalytic activities displayed by single-atom catalysts (SACs) depend on the coordination structure. SACs supported on carbon materials often adopt saturated coordination structures with uneven distributions because they require high-temperature conditions during synthesis. Herein, bisnitrogen-chelated Co SACs that are coordinatively unsaturated are prepared by integrating a Co complex into a conjugated microporous polymer (CMP-CoN2). Compared with saturated analogues, i.e., tetranitrogen-chelated Co SACs (denoted as CMP-CoN4), CMP-CoN2 exhibits higher electrocatalytic activity in polysulfide conversions due to an enhanced hybridization between the 3d orbitals of the Co atoms and the 3p orbitals of the S atoms in the polysulfide. As a result, sulfur cathodes prepared with CoN2 deliver outstanding performance metrics, including a high specific capacity (1393 mA h g-1 at 0.1 C), a superior rate capacity (673.2 mA h g-1 at 6 C), and a low capacity decay rate (of only 0.045% per cycle at 2 C over 1000 cycles). They also outperform sulfur cathodes that contain CMP-CoN4 or CMPs that are devoid of Co SACs. This work reveals how the catalytic activity displayed by SACs is affected by their coordination structures, and the rules that underpin the structure-activity relationship may be extended to designing electrocatalysts for use in other applications.

Evolution of Microstructural and Mechanical Properties of Alloy 617B During Service on a Key-Component Test Platform at 700 °C

The evolution of the microstructural and mechanical properties of alloy 617B during long-term service on a key-component test platform at 700 °C was systematically investigated. The precipitation behavior and size changes of the M23C6 and γ′ phases were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that carbide M23C6 precipitated in the form of discontinuous particles, plates, or needles at grain boundaries and within grains, while the γ′ phase had a spherical shape and was distributed in a dispersed manner. With prolonged service time, both the M23C6 and γ′ phases gradually coarsened. After 24,000 h of service, the yield strength, tensile strength, and Brinell hardness of alloy 617B significantly increased; however, the impact toughness decreased, accompanied by intergranular embrittlement. The increase in precipitate volume fraction and its contribution to the strength of the alloy were evaluated by a precipitation strengthening model. The coarsening of M23C6 was identified as the main cause of embrittlement. The findings of this study provide important experimental data and theoretical support for the stability of 617B alloys under long-term high-temperature service conditions.

Influence of Temperature and Bedding Planes on the Mode I Fracture Toughness and Fracture Energy of Oil Shale Under Real-Time High-Temperature Conditions

The anisotropic fracture characteristics of oil shale are crucial in determining reservoir modification parameters and pyrolysis efficiency during in situ oil shale pyrolysis. Therefore, understanding the mechanisms through which temperature and bedding planes influence the fracture behavior of oil shale is vital for advancing the industrialization of in situ pyrolysis technology. In this study, scanning electron microscopy (SEM), CT scanning, and a real-time high-temperature rock fracture toughness testing system were utilized to investigate the spatiotemporal evolution of pores and fractures in oil shale across a temperature range of 20–600 °C, as well as the corresponding evolution of fracture behavior. The results revealed the following: (1) At ambient temperature, oil shale primarily contains inorganic pores and fractures, with sizes ranging from 50 to 140 nm. In the low-temperature range (20–200 °C), heating primarily causes the inward closure of inorganic pores and the expansion of inorganic fractures along bedding planes. In the medium-temperature range (200–400 °C), organic pores and fractures begin to form at around 300 °C, and after 400 °C, the number of organic fractures increases significantly, predominantly along bedding planes. In the high-temperature range (400–600 °C), the number, size, and connectivity of matrix pores and fractures increase markedly with rising temperature, and clay minerals exhibit adhesion, forming vesicle-like structures. (2) At room temperature, fracture toughness is highest in the Arrester direction (KIC-Arr), followed by the Divider direction (KIC-Div), and lowest in the Short-Transverse direction (KIC-Shor). As the temperature increases from 20 °C to 600 °C, both KIC-Arr and KIC-Div initially decrease before increasing, reaching their minimum values at 400 °C and 500 °C, respectively, while KIC-Shor decreases continuously as the temperature increases. (3) The energy required for prefabricated cracks to propagate to failure in all three directions reaches a minimum at 100 °C. Beyond 100 °C, the absorbed energy for crack propagation along the Divider and Short-Transverse directions continues to increase, whereas for cracks propagating in the Arrester direction, the absorbed energy exhibits a ‘W-shaped’ pattern, with troughs at 100 °C and 400 °C. These findings provide essential data for reservoir modification during in situ oil shale pyrolysis.

Study on the uniaxial tensile mechanical behavior of two-dimensional single-crystal aluminum nitride

Abstract To investigate the tensile behavior and mechanical properties of single-crystal aluminum nitride (AlN) at the microscopic level, molecular dynamics simulations were used to study the effects of crystal orientation, strain rate, environmental temperature, and hole defect size on fracture strength, fracture mechanism, and potential energy during uniaxial tensile. The results show that the tensile strength of AlN in the [100] crystal direction is stronger. The anisotropic behavior characteristics of Al-N bonds fracture mechanism, crack growth rate, and cracking degree are significant when stretched along the [100], [010], and [110] crystal directions. Under high temperature condition, the lattice structure undergoes changes, causing grain boundaries to move and slip. This facilitates the breaking of bonds, leading to a decrease in tensile strength and a reduction in stored potential energy. Hole defects cause more lattice damage, reducing the energy required for Al-N bonds breakage and facilitating the propagation of microcracks. Additionally, it was found that the strain rate affects the stress-strain behavior of the model. An increase in strain rate leads to an increase in breaking stress, and the rapid deformation of AlN results in more energy being stored in the lattice in the form of potential energy. Therefore, the tensile strength and potential energy are improved.

A miniature X-ray diffraction setup on ID20 at the European Synchrotron Radiation Facility.

We describe an ultra-compact setup for in situ X-ray diffraction on the inelastic X-ray scattering beamline ID20 at the European Synchrotron Radiation Facility. The main motivation for the design and construction of this setup is the increasing demand for on-the-fly sample characterization, as well as ease of navigation through a sample's phase diagram, for example subjected to high-pressure and/or high-temperature conditions. We provide technical details and demonstrate the performance of the setup.

Insight into performance and lifetime of ecofriendly pollution barriers in landfill for emergency: A thermogravimetric analysis for novel polymer materials

The novel polymer barrier wall is an in-situ remediation technology designed to effectively control the migration of pollution and prevent the diffusion of pollutants by blocking, sealing, or altering the direction of groundwater flow. With its advantages of rapid chemical reaction (achieving 95 % strength within 15 min) and portable equipment suitable for narrow and rugged emergency sites, this innovative polymer barrier demonstrates promising prospects for practical application. Hence, ensuring the long-term durability of new materials under corrosive and high-temperature leachate conditions is crucial. In this study, a comprehensive investigation was conducted on the corrosion and thermal aging performance of novel polymer materials. Firstly, the mechanical tensile properties of the polymer materials were examined after immersion in leachates, aiming to elucidate the degradation mechanism underlying these properties. Subsequently, thermogravimetric (TG) analysis was performed on the polymer materials immersed in various leachates. And the thermal stability and oxidation stability of novel materials were investigated using a thermogravimetric analyzer coupled with a Fourier transform infrared spectrometer (TG-FTIR). Based on the results obtained from thermal analysis, the service life of polymer materials under different pollutants was ultimately predicted utilizing the Arrhenius model. The findings indicate that the novel polymer materials exhibit commendable durability and pose little risk of causing secondary pollution.

High-Pressure Synthesis of Te-Ge Double-Substituted Skutterudite with Enhanced Thermoelectric Properties.

We synthesized Co4Sb11TexGe1-x (x = 0.5-0.8) using high-pressure, high-temperature conditions at ∼2 GPa and ∼900 K. The microstructure, morphology, and components were characterized via X-ray diffraction, scanning electron microscopy, and electron backscatter diffraction (EBSD). EBSD indicated that the average grain size of Co4Sb11Te0.8Ge0.2 was 1 μm. Electrical conductivity, Seebeck coefficient, and thermal conductivity were measured from 300 to 800 K. The minimum lattice thermal conductivity of Co4Sb11Te0.8Ge0.2 was 0.72 W m-1 K-1, 74% lower than that at 300 K. The introduction of Te and Ge effectively enhanced point effects scattering and location scattering, notably decreasing lattice thermal conductivity. Therefore, the maximum zT value of Co4Sb11Te0.8Ge0.2 was 1.13 at 800 K. These results indicate that high pressure combined with multielement substitution optimized the thermoelectric transport properties of skutterudites.

Dual-phase Cs4PbBr6/CsPbBr3 perovskite quantum dot borosilicate glass for WLED applications

Owing to inherent structural instability of perovskite quantum dots, they are instability in humid environments and high temperatures conditions. To address this issue, a simple, environmentally friendly glass encapsulated technology is used to protect the perovskite quantum dots. Meanwhile, the dual-phase perovskite structure realized by phase transition engineering can further increase the stability of perovskite quantum dots. In this study, 3D CsPbBr3/0D Cs4PbBr6 dual-phase coexisting perovskite quantum dot glass powders were synthesized through melt quenching and subsequent crystallization induction of thermal treatment and water molecule, respectively. Results showed that compared with thermal treatment induction, perovskite QDs glass powders by water molecules induction exhibited a high PLQY of 24.7 % with a central wavelength of 519 nm and displayed excellent environmental stability. By combining green fluorescence from 3D CsPbBr3/0D Cs4PbBr6 QDs glass powders and red fluorescence powders (CaAlSiN3:Eu), a WLED device with an impressive EQE of 20.6 % was created, indicating a promising application potential.

Parametric Analysis and Improvement of the Johnson-Cook Model for a TC4 Titanium Alloy

Titanium alloys are widely used in the manufacture of gas turbines’ compressor blades. Elucidating their mechanical behavior and strength under damaged conditions is the key to evaluating the equipment’s reliability. However, the conventional Johnson-Cook (J-C) constitutive model has limitations in describing the dynamic response of titanium alloy materials under the impact of a high strain rate. In order to solve this problem, the mechanical behavior of a TC4 titanium alloy under high strain rate and different temperature conditions was analyzed by combining experiments and numerical simulations. In this study, the parameters of the J-C model were analyzed in detail, and an improved J-C constitutive model is proposed, based on the new mechanism of the strain rate strengthening effect and the temperature softening effect, which improves the accuracy of the description of strain sensitivity and temperature dependence. Finally, the VUMAT subroutine of ABAQUS software was used for numerical simulation, and the predictive ability of the improved model was verified. The simulation results showed that the maximum prediction error of the traditional J-C model was 23.6%, while the maximum error of the improved model was reduced to 5.6%. This indicates that the improved J-C constitutive model can more accurately predict the mechanical response of a titanium alloy under an impact load and provides a theoretical basis for the study of the mechanical properties of titanium alloy blades under subsequent conditions of foreign object damage.

Highly Robust, Pressureless Silver Sinter-Bonding Technology Using PMMA Combustion for Power Semiconductor Applications

This study presents the development of a highly robust, pressureless, and void-free silver sinter-bonding technology for power semiconductor packaging. A bimodal silver paste containing silver nanoparticles and sub-micron particles was used, with polymethyl methacrylate (PMMA) as an additive to provide additional thermal energy during sintering. This enabled rapid sintering and the formation of a dense, void-free bonding joint. The effects of sintering temperature and PMMA content on shear strength and microstructure were systematically investigated. The results showed that the shear strength increased with rising sintering temperatures, achieving a maximum of 41 MPa at 300 °C, with minimal void formation due to enhanced particle necking facilitated by PMMA combustion. However, at 350 °C, the shear strength decreased to 35 MPa due to cracks and voids at the copper substrate–copper oxide interface caused by thermal expansion mismatch. The optimal PMMA content was found to be 5 wt.%, balancing sufficient thermal energy and void reduction. This pressureless sintering technology demonstrates significant potential for high-reliability applications in power semiconductor modules operating under high-temperature and high-stress conditions.

Thermal-gas-elastic coupling modeling and performance analysis of foil cylindrical gas film seal considering speed slip, temperature jump and shaft misalignment

Abstract The Compliant foil cylindrical gas film seal is an advanced sealing technology designed for high-speed and high-temperature conditions in a jet engine. Its design involves using a compliant foil to create a cylindrical sealing surface, achieving adaptive sealing in environments with high pressure differences and rotational speeds. For high-speed and high-temperature operation, a speed slip flow model was established by considering film slip flow, wall temperature jump, foil deformation, and gas viscosity-temperature thermal effects. The variations in the lubrication performance of the foil cylindrical gas film seal with changes in shaft misalignment directions, misalignment angles, and operating parameters were investigated. The speed slip leads to a decrease in gas film lift and an increase in leakage. The wall temperature jump phenomenon caused by speed slip leads to a 2.56% decrease in film temperature. The shaft misalignment angles on the high-pressure and low-pressure sides have different impacts on the flow field, with film pressure and temperature differing by 66.78% and 11.19%, respectively.

Comparative study on the cleanliness and compositional change of alloy steels processed by electroslag remelting and vacuum arc remelting

The cleanliness and compositional change of Ni containing alloy steel processed by electroslag remelting (ESR) and vacuum arc remelting (VAR) were studied. The results show that compared with the electrode steel, the total oxygen content increases in the steel processed by ESR. On the contrary, the total oxygen and total nitrogen content in the steel processed by VAR can be significantly decreased due to the vacuum environment. The number and size of inclusions in steel processed by VAR are significantly decreased, which indicates that the VAR is conducive to improving the cleanliness of steel. Single TiN inclusions are found in both steels processed by ESR and VAR, and oxide inclusions in two steels are (Mg,Al,Ca)O and (Mg,Al)O, respectively. The growth time of TiN inclusions is relatively shorter in the steel processed by VAR, which leads to the thinner TiN layer surrounding the oxide inclusions. During the VAR process, the high temperature and high vacuum conditions promote the volatilization of Mn in steel, leading to decrease of the Mn content in steel. Therefore, extra Mn should be added to the electrode steel before VAR.

Electrical Conductivity of Multiphase Garnet under High-Temperature and High-Pressure Conditions

Electrical Conductivity of Multiphase Garnet under High-Temperature and High-Pressure Conditions

Thermal Conductivity of Polymers: A Simple Matter Where Complexity Matters.

Thermal conductivity coefficient κ measures the ability of a material to conduct a heat current. In particular, κ is an important property that often dictates the usefulness of a material over a wide range of environmental conditions. For example, while a low κ is desirable for the thermoelectric applications, a large κ is needed when a material is used under the high temperature conditions. These materials range from common crystals to commodity amorphous polymers. The latter is of particular importance because of their use in designing light weight high performance functional materials. In this context, however, one of the major limitations of the amorphous polymers is their low κ, reaching a maximum value of ≈0.4 W/Km that is 2-3 orders of magnitude smaller than the standard crystals. Moreover, when energy is predominantly transferred through the bonded connections, κ ⩾ 100 W/Km. Recently, extensive efforts have been devoted to attain a tunability in κ via macromolecular engineering. In this work, an overview of the recent results on the κ behavior in polymers and polymeric solids is presented. In particular, computational and theoretical results are discussed within the context of complimentary experiments. Future directions are also highlighted.

Optimized emamectin benzoate trunk injection: addressing temperature limitations for pine wilt disease control.

Pine wilt disease (PWD), caused by the pinewood nematode Bursaphelenchus xylophilus, poses a significant threat to global forestry, resulting in extensive economic and ecological damage. Traditional trunk injection agents (TIAs) are limited by environmental factors, such as high winter temperatures and vigorous resin flow, particularly in southern China. This study aimed to develop an ordinary temperature trunk injection agent (OTTIA) for year-round application and to evaluate its performance under high-temperature conditions in comparison to commercial TIAs. Extensive laboratory and field tests identified N,N-Dimethylformamide (DMF) and benzyl acetate as optimal solvents and Tween-40 as an effective emulsifier for the OTTIA formulation. The new agent was fully absorbed by Pinus massoniana within 3 h at temperatures exceeding 30 °C, outperforming existing commercial agents. Treated trees maintained comparable emamectin benzoate (EB) levels but achieved lower LC90 lethal concentration values (27.65 mg L-1), indicating greater efficacy. The OTTIA provided protection against PWD for ≤360 days postinjection. The development of OTTIA marks a significant advancement in PWD management, offering an effective solution for high-temperature regions and potentially transforming year-round treatment strategies. The results highlight the critical role of optimizing solvent and emulsifier combinations to enhance the efficacy and application of trunk injection agents, contributing to sustainable forest management and improved protection against PWD. © 2024 Society of Chemical Industry.

Review of Laser Powder Bed Fusion’s Microstructure and Mechanical Characteristics for Al-Ce Alloys

As a new alloy manufacturing method that can break through the limitations of molds to manufacture fine parts, laser powder bed fusion has recently become a common process for producing aluminum alloys. In the fields of aerospace or automotive, aluminum alloys with both good printability and good mechanical performance in high-temperature conditions are greatly demanded, and the Al-Ce alloy is one of the alloys with significant potential. Therefore, systematic research on the additive manufacturing of Al-Ce alloys is still being explored. Herein, we review the recent progress and current status of laser powder bed fusion-produced Al-Ce alloys, giving our opinions on the development of this alloy system. Element composition, alloy powders, laser powder bed fusion parameters, microstructures, and mechanical properties at room temperature and high temperatures are summarized. The choice of alloying strategies is crucial for a specific mechanical improvement of the Al-Ce alloys. Finally, the details of the Al-Ce alloys manufactured via laser powder bed fusion are presented.