High Temperature Field Research Articles

THE APPLICATION OF ANALYSIS OF VARIANCE TO DIFFERENT IRON‑BASED SUPERCONDUCTOR CRITICAL TEMPERATURE MODELING

Recently, Iron-based superconductors have shown promising properties of high critical temperature and high upper critical fields, which are prerequisites for applications in highfield magnets. Extensive research has been conducted on a modeling approach that contributes to predicting doped Iron-based superconductor critical temperature from structural and topological parameters. Statistical significance of differences in modeling approaches requires studies that can reliably distinguish between systematic approach effects and errors resulting from modeling approach variation. In this work, we introduce analysis of variance (ANOVA) to assess the statistical significance of differences in modeling approach variation. Comparisons of obtained results with Iron-based modeling approach variation data of support vector machine (SVM) and linear regression with natural logarithm transformation (LRNLT) were presented.

Spiral-Structured Dielectric Polymers Exhibiting Ultrahigh Energy Density and Charge-Discharge Efficiency at High Temperatures.

The growing need for high-power and compact-size energy storage in modern electronic and electrical systems demands polymer film capacitors with excellent temperature capability. However, conventional polymer dielectrics feature dramatic deterioration in capacitive performance under concurrent high temperature and electric field because the high thermal stability traditionally relies on the conjugated, planar molecular segments in the polymer chains. Herein, inspired by the stable double helix structures of deoxyribonucleic acid, spiral-structured dielectric polymers that exhibit simultaneous high thermal stability and great capacitive performance are demonstrated. Both the experimental results and computational simulations confirm that the spiral groups serve to weaken the electrostatic molecular interaction, induce proper molecular chain stacking structure, and regulate the charge transfer process by breaking the conjugated planes and introducing deep trap sites. The resultant polymer exhibits the maximum discharged energy densities of 7.29 and 6.13 Jcm-3 with the charge-discharge efficiency above 90% at 150 and 200°C, respectively, more than ten times those of the original dielectric at the same conditions. Here a completely new dimension is offered for the molecular design of polymers, giving rise to well-balanced thermal and dielectric properties, and ultimately the desired capacitive energy storage performance at high temperatures.

Fully 3D-printed tortoise-like soft mobile robot with muti-scenarios adaptability.

Soft robotic systems are well suited to unstructured, dynamic tasks and environments, owing to their ability to adapt and conform without damaging themselves or their surroundings. These abilities are crucial in areas such as human-robot interaction，simplification of control system and weight reduction. However, as the requirements increase, the drawbacks of existing soft mobile robots such as single locomotion mode and application scenarios, manufacturing difficulties and low energy conversion efficiency gradually emerge.
Based on the current shortcomings of soft robots, this paper designs and proposes a fully 3D-printed tortoise-like soft mobile robot with muti-scenarios adaptability. The robot uses a Bionic Tortoise Leg Actuator structure that enables simultaneous bending of the actuator in both directions, simplifying robot control and increasing the maximum bending angle achievable. In addition, a reconfiguration design solution has been proposed to enable the robot to implement two bionic modes for land and sea tortoises, adapting to move on hard and soft surfaces and in water, enabling it to move in amphibious and complex environments. The performance of the pneumatic soft actuators are also improved by an improved Digital Light Processing method that enhances the maximum strain of the 3D printed soft material.
The prototype was tested to give maximum movement speeds for different gaits and environments, demonstrating that the fully 3D printed turtle-like soft-mobile robot designed in this paper is highly adaptable to multiple scenarios. The robot studied in this paper has a wide range of applications, with potential applications including navigation in a variety of domain environments, inspection of large underground oil and gas pipelines, and navigation in high temperature, high humidity and strong magnetic field environments or in military alert conditions.&#xD.

Evidence of a distal axis inactive high-temperature hydrothermal field on the ultraslow spreading Southwest Indian Ridge: Insights from mineralogy and geochemistry studies

The development of hydrothermal activities on mid-ocean ridges is primarily influenced by magmatic and tectonic activities close to the ridge axis. On slow and ultraslow spreading ridges featured by limited magma supply, prolonged hydrothermal activity can also occur in non-transform offsets (NTO), where sustained ultramafic-related hydrothermal circulation happens due to prolonged hydrothermal processes associated with the expose of ultramafic rocks. In contrast, basalt-hosted hydrothermal fields are barely developed in NTOs, especially in off-axis area, due to insufficient magma supply. In this study, we reported the occurrence of a distal axis (∼9.5 km) basalt-hosted hydrothermal field (50.63°E) on the NTO of segment 27 of the ultraslow spreading Southwest Indian ridge. The hydrothermal products are characterized by layered crusts mainly composed of oxides, such as limonite and goethite, rich in Fe and depleted in Si. These crusts contain high contents of trace elements derived from seawater, such as P, As, Mo, U, and Sb and show REE pattens with negative Eu and mostly positive Ce anomalies. However, the high Cu content (1.82 ± 0.89 wt%, N = 27), low absorption ratio of Cu (18.39 ± 12.71%, N = 9), and residual chalcopyrite altered by goethite suggest prior high-temperature hydrothermal activity. Lead isotopic composition with basaltic rocks signatures that distinct from those of low-temperature crusts of seawater origin also support this conclusion. The Fe-rich crusts appears to be the result of high-temperature sulfides altered by late-stage low-temperature diffuse flow. This field is currently the furthest known distal axis basalt-hosted hydrothermal field located in NTOs of ultraslow spreading ridges. The hydrothermal circulation is likely due to a combination of off-axis normal fault and gabbro diking. Our results emphasize the occurrence of distal axis basalt-hosted high-temperature hydrothermal activities on NTOs of ultraslow spreading ridges, and may lead to an increased estimation of hydrothermal heat and chemical influx to the ocean.

Sandwich-structured BOPET films with high energy density and low loss for high temperature film capacitors

Film capacitors have widely been used in modern electrical/electronic equipment because of their high insulation property and high-power density. However, the traditional dielectric films suffered a high conduction loss under high temperature and electric field conditions, which leads to the depression of high temperature energy storage properties. Herein, sandwich-structured composite films using biaxially oriented polyethylene terephthalate (BOPET) as the outer layers were prepared to construct the interfacial barrier, which was beneficial for hindering the propagation of breakdown path. In addition, epoxy resin was applied as the adhesive inner layer to bind the outer layers up tightly, while the boron nitride nanosheets (BNNSs) in the inner layer further improved the breakdown strength of the film and inhibited the conduction loss, especially under high temperature and electric field conditions. The composite film with optimized BNNSs content had a high discharged energy density of 9.11 J/cm3 and a ultrahigh charge–discharge efficiency of 95% at 25 °C, while the values were 6.45 J/cm3 and 70% at 150 °C, respectively, of which both were much higher than those of pure BOPET. Thus, the sandwich-structure method points out a promising way of preparing dielectric films with excellent energy storage performances.

Corrosion Analysis and Prevention of Tubing Nipples in Four Wells

A high-temperature and high-pressure gas field in an oil field requires the use of super 13 chromium material due to corrosive environments. In the recent production process, there have been four consecutive cases of corrosion, fracture, and perforation of tubing nipples, which have brought enormous economic losses to the oilfield. This article analyzes the failure causes of these four tubing nipples and proposes preventive measures. In this paper, the macroscopic morphology, chemical composition, mechanical properties, metallography, and microscopic morphology of four failed tubing nipples have been analyzed. Combined with the field service conditions and string structure of the tubing nipples, it is believed that the failure of the tubing nipples is mainly due to the connection of carbon steel and stainless steel materials, forming a typical galvanic corrosion galvanic cell. The geometric and environmental factors of the materials exacerbate this corrosion. Eventually, severe galvanic corrosion occurred on the inner surface of the tubing nipple, resulting in severe wall thinning or partial perforation, and four tubing nipples failed. The failed tubing nipples in Wells A, B, and C have erosion marks, which are caused by the action of high pressure and high flow rate fluids in the well; The inner surface of the tubing nipple in Well D is rusty yellow, mainly due to the corrosion of its inner wall caused by the acid fracturing fluid injected earlier. At the same time, the string structure of four wells shows that the tubing nipple is located at the variable diameter node of the string. When the fluid in the well flows from the large hole into the smaller hole, the fluid in the well will change there, and its flow rate and pressure will also increase, further exacerbating the erosion in this area. With the development of deep wells containing carbon dioxide in oil fields and the application of carbon dioxide injection secondary oil recovery technology, the use of 13Cr martensitic stainless steel is also increasing. In order to avoid the occurrence of similar accidents that will bring huge economic losses to the oil field, it is recommended that the material of the pipe string (including accessories) of such wells be confirmed using a portable direct reading spectrometer before entering the well.

HCM-LMB Filter: Pedestrian Number Estimation with Millimeter-Wave Radar in Closed Spaces

The electromagnetic wave transmitted by the millimeter-wave radar can penetrate flames, smoke, and the high-temperature field, and is the main sensor for detecting disaster victims in closed spaces. However, a moving target in the closed space will produce a considerable number of false detections in the point cloud data collected by the radar due to multipath scattering. The false detections lead to false trajectories generated by multi-target tracking filters, such as the labeled multi-Bernoulli (LMB) filter, which, therefore, leads to inaccurate estimation of the number of pedestrians. Addressing this problem, in this paper, a three-class combination of the clutter point clouds model is proposed: static clutter, non-continuous dynamic clutter (NCDC), and continuous dynamic clutter (CDC). The model is based on the spatial and temporal distribution characteristics of the CDC sequence captured by a two-dimensional (2D) millimeter-wave (MMW) radar. However, in open space, CDC appears infrequently in radar tracking applications, and thus has not been considered in multi-target tracking filters such as the LMB filter. This leads to confusion between the CDC point cloud collected by the high-resolution radar in closed spaces and the real-target point cloud. To solve this problem, the impact mechanism of the LMB filter on prediction, update, and state estimation is modeled in this paper in different stages based on the temporal and spatial distribution characteristics of CDC. Finally, a hybrid clutter model-based LMB filter (HCM-LMB) is proposed, which focuses on scenes where NCDC and CDC are mixed. The filter introduces the temporal and spatial distribution characteristics of NCDC based on the original LMB filter, and improves the prediction, update, and state estimation of the original filter by combining the impact mechanism model and the new CDC prediction, CDC estimation, and false trajectory label management algorithm. Experiments were conducted on pedestrians in building corridors using 2D MMW radar perception. The experimental results show that under the influence of CDC, the total number of pedestrians estimated by the HCM-LMB filter was reduced by 22.5% compared with that estimated by the LMB filter.

Doped effect of Yb on enhancing resistance to calcium-magnesium-alumina-silicate corrosion of Sm2(Zr0.7Ce0.3)2O7

Four kinds of (Sm1−xYbx)2(Zr0.7Ce0.3)2O7 (x = 0, 0.1, 0.2, 0.3) ceramics with different contents of Yb were prepared by the solid-phase reaction. Their thermochemical reaction behaviors with calcium-magnesium-alumina-silicate (CMAS) at 1300 °C were investigated. Among them, (Sm0.7Yb0.3)2(Zr0.7Ce0.3)2O7 has the best corrosion resistance to CMAS. The increase of Yb content can accelerate the formation rate of apatite, preventing the ceramic layer from erosion of CMAS and improving the strain tolerance of the ceramic. In addition, the CMAS wetting, corrosion process and failure mechanisms were discussed by high-temperature field wetting and transmission electron microscopy.

Polyarylene ether nitrile dielectric films modified by HNTs@PDA hybrids for high-temperature resistant organic electronics field

Abstract In this work, mussel-inspired surface functionalization of halloysite nanotubes (HNTs) were coated by in situ self-polymerization of polydopamine (PDA) to synthesize core-shell structural composites (HNTs@PDA), and then incorporated into polyarylene ether nitrile (PEN) matrix. Due to the strong adhesion of the PDA modification layer and the formation of hydrogen bonds between the polar nitrile group of PEN and the catechol group of PDA, the dispersion and interfacial compatibility of HNTs@PDA in the PEN matrix are improved. The results show that the dielectric constant of PEN/HNTs@PDA 20 nanocomposites reaches 11.56 (1 kHz), which is 3.2 times that of pure PEN. In addition, after heat treatment, a chemical cross-linking reaction occurred between the PEN matrix to form a cross-linked PEN (CPEN) based nanocomposites, which further improved the thermal stability of the nanocomposites. The results show that the T g of CPEN/HNTs@PDA 20 nanocomposites reaches 215.5°C, which is 47.7°C higher than that of PEN/HNTs@PDA 20. Moreover, the dielectric constant-temperature coefficient of all CPEN nanocomposites is less than 7 × 10−4°C−1 at the temperature range of 25–180°C. All in all, this work provides a simple and environmentally friendly strategy to adjust the dielectric properties of polymer-based ceramic nanocomposites, which provides a pathway for its application as a dielectric material in the film capacitors field.

Investigation of the high-temperature field distribution characteristics for a multi-jet burner by OH-PLIF and coherent anti-Stokes Raman spectroscopy

The construction of a high-temperature gas calibration source is of great significance since it can provide an effective high-temperature experimental environment for, e.g. verifying high-temperature measurement techniques and studying high-temperature combustion mechanisms. Here, we try to obtain a high-temperature gas field on a multi-jet burner by controlling the gas supplies to it. We use OH planar laser-induced fluorescence (OH-PLIF) to observe the compositional uniformity of the field and coherent anti-Stokes Raman scattering (CARS) to investigate the temperature uniformity of the field. We find from OH-PLIF images that the distribution of OH between the adjacent jets becomes more uniform with the increasing flow rate of CH4, and the flow rate of the co-flow N2 around jets also affects the uniformity of OH distribution. The measured temperature distribution by CARS is consistent with the OH distribution. At the jet outlet location, the temperature distribution had a periodic variation and gradually became more uniform with the height increased from the jet outlet. We find that the flow rate of CH4 and co-flow N2 and the radiative heat transfer rate play an important role in temperature distribution for the multi-jet burner. Also, the results show that a wide range of temperatures can be constructed by regulating the recipe of the gas supplies, and the highest temperature achieved in this work is 2457 K.

An innovative wood derived carbon-carbon nanotubes-pyrolytic carbon composites with excellent electrical conductivity and thermal stability

The functionality of wood has evolved with time to adapt to the emerging needs of society. Carbonized wood-based composites have attracted tremendous interest in the fields of aerospace, military power, electric power, and system electronic devices, especially at high temperatures. Nevertheless, their electrical conductivity and thermal stability characteristics are still far from satisfactory. Herein, an innovative wood-derived carbon-carbon nanotubes-pyrolytic carbon composites (WDC-CNTs-PyCs) is successfully fabricated by chemical vapor deposition and chemical vapor infiltration. The combination of wood-derived carbon (WDC), carbon nanotubes (CNTs), and pyrolytic carbon (PyC) has never been reported in any previous work. We have innovatively introduced PyC into the WDC by chemical vapor infiltration. CNTs promote the continuous deposition of PyC to form dense structures. WDC-CNTs-PyC demonstrates significant compressive strength (85.4 MPa) and excellent electrical conductivity (632 S cm–1). The weight loss rate of WDC-CNTs-PyC is 6% after heating at 500 °C for 10 min in the air atmosphere. Furthermore, WDC-CNTs-PyC could resist oxyacetylene ablation above 2300 °C for 15 s. With excellent electrical conductivity, outstanding thermal stability, and mechanical properties, WDC-CNTs-PyC opens up a surprising strategy for efficiently fabricating various high-performance electronic device composites that could be used in high-temperature fields.

Research progress and prospect of polymer dielectrics

With the increasing demand for energy, how to store and release energy efficiently and stably has become an urgent research topic. Polymer dielectrics have become a kind of ideal dielectric materials in electrostatic capacitors for energy storage due to their advantages of light weight, easy fabrication, low cost, and high breakdown strength. It has a wide application prospect in smart power grids, new energy vehicles, pulse power weapons, electromagnetic guns, and lasers. However, existing polymer dielectrics cannot simultaneously possess the characteristics of high energy density, high breakdown field intensity, high charge and discharge efficiency, and low dielectric loss, thus limiting the development of compact, efficient, and reliable electronic power technology. In addition, the inherent thermal/field charge injection, excitation, and transport phenomena of polymer dielectrics make the resistivity and dielectric energy storage properties of polymer dielectrics decrease sharply under the combined action of high temperature and high electric field. In order to optimize the energy storage performance of polymer dielectrics (including room temperature and high temperature dielectrics), it has been obtained excellent dielectric breakdown strength, energy storage density, energy storage charge, and discharge efficiency from polymer nanocomposites, polymer/small molecule composites, polymer/polymer blends, new synthetic polymers, multilayer polymers, and other material systems. Based on these material systems, this review summarizes and compares these material systems, points out their advantages and disadvantages including the key problems, and puts forward suggestions for the future research.

La(Ca)CrO3-Filled SiCN Precursor Thin Film Temperature Sensor Capable to Measure up to 1100 °C High Temperature.

Thin-film sensors are regarded as advanced technologies for in situ condition monitoring of components operating in harsh environments, such as aerospace engines. Nevertheless, these sensors encounter challenges due to the high-temperature oxidation of materials and intricate manufacturing processes. This paper presents a simple method to fabricate high temperature-resistant oxidized SiCN precursor and La(Ca)CrO3 composite thin film temperature sensors by screen printing and air annealing. The developed sensor demonstrates a broad temperature response ranging from 200 °C to 1100 °C with negative temperature coefficients (NTC). It exhibits exceptional resistance to high-temperature oxidation and maintains performance stability. Notably, the sensor's resistance changes by 3% after exposure to an 1100 °C air environment for 1 h. This oxidation resistance improvement surpasses the currently reported SiCN precursor thin-film sensors. Additionally, the sensor's temperature coefficient of resistance (TCR) can reach up to -7900 ppm/°C at 200 °C. This strategy is expected to be used for other high-temperature thin-film sensors such as strain gauges, heat flux sensors, and thermocouples. There is great potential for applications in high-temperature field monitoring.

A novel method for spatiotemporal temperature prediction in offices by using Raman-distributed fiber-optic sensor with the data fusion method

The uneven distribution of temperature fields and dynamic personnel disturbance in open-plan offices are key research issues for achieving high-precision prediction of temperature fields. Using Raman-distributed fiber-optic sensors, we developed a novel method for predicting working area temperature in open-plan offices. The novelty of this study is that the proposed temperature prediction method can incorporate thermal environment changes caused by dynamic internal disturbances, which not only improves the temperature prediction accuracy, but also enables low-cost, high-density temperature field prediction. The method aimed to achieve high spatial resolution and strong generalizations for the temperature field, considering uneven temperature distributions and random personnel disturbances. An environmental adaptability calibration method was developed, reducing the measurement error to 0.09 °C. Using Computational Fluid Dynamics (CFD) transient simulation, we established a human impact quantification dataset for open-plan offices. Combining distributed fiber-optic sensors, the YOLO personnel recognition algorithm, and the human impact quantification dataset, we achieved temperature field prediction of personnel activity areas with an error of approximately 0.1 °C. The method's performance was validated through field experiments conducted in an open-plan office in Tianjin. The proposed low-cost, high spatial resolution temperature field prediction method can significantly improve temperature data acquisition accuracy for intelligent operation and maintenance of office buildings. Furthermore, it can provide data support for pre-adjustment control of indoor thermal environments by air conditioning systems through early temperature prediction, enabling further exploration of energy-saving and carbon reduction potentials in office building operations.

Hydrogeochemistry and isotopic assessment of a new geothermal prospect in rancho Nuevo (Guanajuato-Central Mexico)

Mexico has five high-temperature geothermal fields, three of which are located in an active volcanic arc known as the Trans-Mexican Volcanic Belt in central Mexico. In this geological province, there are numerous hot springs, many of which have not been studied yet. It is the case of the Rancho Nuevo area, which is composed of two hot springs and thermal groundwater wells. The present study focuses on the hydrogeochemical and isotopic characterization of the Rancho Nuevo geothermal system. According to the results cationic exchange, silicates and carbonates rock alteration processes are occurring. A cooling of thermal water is also carried out caused by a mixing process between deep Na-Cl type water and shallow Na-HCO3. In addition, the most relevant process identified in the study area is the water-rock interaction and corroborated by the stable isotope results showing enrichment of δ18O. All these processes are enhanced by the thermal activity in the region. The CO2 and N2 concentrations confirm the geothermal activity in the Rancho Nuevo area. The CH4 concentration is also typical of geothermal fluids and may represent a magma degassing.Finally, the reservoir temperature was estimated at 225 °C ± 15 °C based on silica, cation, and integrated multicomponent solute geothermometers. Therefore, the Rancho Nuevo geothermal area can be defined as a high-temperature system and as a very interesting prospect; however, for geothermal resource production, the calcium carbonate deposition in the wells shall be considered.

Urban heat islands and their effects on thermal comfort in the US: New York and New Jersey

In recent decades, urbanization and the dramatic increase in urban populations have exacerbated the urban heat island effect. At present, much attention has been paid to the causes and patterns of the urban heat island effect. However, there are few quantitative studies on the impact of the urban heat island effect. By extracting post-world climate data, DEM data, and land use data for 20 years between 2001 and 2020, this paper first studies the variation pattern and spatial distribution characteristics of urban heat islands in New York State, summarizes the seasonal distribution characteristics of temperature, and then uses Giles formula to calculate Tom's discomfort index and evaluate human thermal comfort, and evaluates the effect of heat island effect on human sensory thermal comfort. The results show that on the time scale, the surface temperature in the study area generally showed a slow upward trend over the past 20 years. For example, in July, the maximum and minimum temperatures increased by 3.2 °C and 4.1 °C, respectively. At the spatial scale, most of the heat island areas in the study area were distributed in the New York City agglomeration, especially from May to October, when the heat island effect was particularly obvious. The temperature map showed obvious high temperatures. Compared with 2001, the human discomfort index (DI) increased between June and August 2020. The land use map shows that as the city expands, people's DI index also increases, and the proportion of people who feel uncomfortable with heat increases to 50%. Except for the New York City cluster, other areas were mostly athermic-free. This result shows that excessive urban development concentration seriously affects residents' quality of life. We should pay attention to the superimposed impact of climate change and urban heat islands on the human discomfort index, and adjust the local high temperature and thermal field area through reasonable planning, strengthening greening, and using building technology to make cities more livable.

Geochemical and H–O–Sr–B isotope signatures of Yangyi geothermal fields: implications for the evolution of thermal fluids in fracture-controlled type geothermal system, Tibet, China

High-temperature hydrothermal systems are mainly distributed in the north–south graben systems of southern Tibet as an important part of the Mediterranean–Tethys Himalayan geothermal belt in mainland China. As the largest unit capacity and second stable operating geothermal power station in China, Yangyi is the fracture-controlled type geothermal field in the center of Yadong–Gulu Graben. In this paper, hydrogeological and hydrochemical characteristics, isotope composition (δD and δ18O, 87Sr/86Sr and δ11B) of borehole water, hot springs, and surface river samples were analyzed. From the conservative elements (such as Cl− and Li+) and δD and δ18O values, the geothermal water of the Yangyi high-temperature geothermal field is estimated to be of meteoric origin with the contributions of chemical components of the magmatic fluid, which is provided by partially molten granite as a shallow magmatic heat source. According to logging data, the geothermal gradient and terrestrial heat flow value of the Yangyi high-temperature geothermal field are 6.48 ℃/100 m and 158.37 mW m−2, respectively. Combining the hydrothermal tracer experiment, 87Sr/86Sr and δ11B ratios obtained with gradually decreasing reservoir temperatures from the Bujiemu stream geothermal zone to Qialagai stream geothermal zone, we suggested the deep geothermal waters were mixed with local cold groundwater and then flow northeastward, forming the shallow reservoir within the crushed zone and intersect spot of faults in the Himalayan granitoid. Furthermore, in the process of ascent, the geothermal water is enriched in K+, Na+, and HCO3− during the interaction with underlying Himalayan granitoid and pyroclastic rocks that occur as wall rocks. The detailed description and extensive discussion are of great significance for the further exploitation and utilization of north–south trending geothermal belts in Tibet.

Investigation on mechanical and thermal properties of MgAl2O4-Mg2TiO4 solid solutions with spinel-type structure

Magnesium aluminate (MA) spinel has shown potential as a refractory material under harsh environments, such as high temperatures and frequent temperature variations. However, understanding the mechanical and thermal properties of MA spinel is a key step towards further improvement of MA spinel refractory materials in high-temperature fields. The formation of solid solution represents a prominent strategy to improve mechanical and thermal properties. The present study develops novel (1-x)MgAl2O4-xMg2TiO4 (0≤ x ≤ 0.1) solid solutions by single-step reaction sintering method using light-burned magnesia, reactive alumina, and as-prepared Mg2TiO4 (M2T) powders. The effects of M2T content on the crystal structure, mechanical properties, and thermal properties of the MgAl2O4-Mg2TiO4 solid solutions (MATss) were studied. Based on XRD, TEM, and HRTEM results, MATss were highly crystallized with a cubic spinel structure. Besides, the M2T addition facilitated the flexural strength, hardness, and elastic modulus in the MA spinel. Among these solid solutions, the x = 0.08 sample exhibited the highest flexural strength, hardness, and elastic modulus of 219.47 MPa, 19.99 GPa, and 270.2 GPa, respectively. M2T additive played a solid-solution strengthening role, which enhanced the inherent resistance to microstructural damage. Additionally, the x = 0.08 sample had the highest thermal conductivity and thermal diffusivity of 12.45 W/(m·K) and 7.98 mm2/s, respectively. In comparison with pure MA spinel, the x = 0.08 sample showed a lower thermal expansion coefficient (8.63 × 10-6 K-1 at 1550 °C). These excellent mechanical properties and exceptional thermal behavior enabled its widespread application in refractory materials.

A Double Rotor Flux Switching Machine With HTS Field Coils for All Electric Aircraft Applications

The increasing demand for high-power density motors in electric transport industries opens a new research opportunity to develop motor topologies with less weight and high efficiency. In particular, all-electric aircraft applications require very high power density motors. This paper shows the design of a new 1 MW 20-pole/15-slot double rotor flux switching machine with high-temperature superconducting field coils and thermal management system. The proposed motor features an air-core stator. Aluminum Litz wire is used for the armature conductors, and the YBCO- high-temperature superconducting material is used for the field coils. The armature winding and field coils operate at 95K and 65K, respectively. The active part power density including rotors, armature windings and field coils obtained with the proposed design is 29.3kW/kg. The specific power density of proposed motor considering mechanical, support structure and TMS is about 18.5 kW/kg. The efficiency can be higher than 98.7% which satisfies the requirement of electric aviation.

Formation mechanism of Cube texture components ({001}) associated with dynamic recrystallization during compression in the single BCC phase region of Ti-22Al-25Nb alloy

The present study, employing EBSD as the primary method, investigates the formation mechanism of Cube texture components in Ti-22Al-25Nb alloy during uniaxial compression at high-temperature single-phase field. The research reveals that the formation of Cube components is closely related to texture evolution and dynamic recrystallization (DRX) behavior. Firstly, the formation of <001> and <111> dual fiber texture structures is a prerequisite for the development of Cube component, which mainly forms under large strains. Subsequently, continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) play distinct roles in the formation of Cube component. CDRX and DDRX occur in grains belonging to <001> and <111> fiber textures, respectively, exhibiting significant orientation dependence. <001> grains, characterized by a lower Taylor factor, undergo CDRX, causing sub-grains near the grain boundaries in <001> grains to rotate towards the Cube orientation. In contrast, <111> grains with a higher Taylor factor undergo DDRX, leading to the accumulation of high stored energy near the grain boundaries in <111> grains. When the two types of grains are adjacent, the significant orientation difference between them facilitates the rapid growth of Cube-oriented sub-grains through grain boundary migration. This results in a conspicuous Cube texture component on a macroscopic scale.