Temperature Interval Research Articles

Effect of Pyrolysis Temperature on the Carbon Sequestration Capacity of Spent Mushroom Substrate Biochar in the Presence of Mineral Iron

The preparation of biochar typically involves the pyrolysis of waste organic biomass. Iron-rich magnetic biochar not only inherits the characteristics of high specific surface area and porous structure from biochar but also possesses significant advantages in easy separation and recovery, which has shown great application potential in various fields such as soil improvement and water resource remediation. This study aims to explore the influence of mineral iron on the carbon sequestration capability of biochar during the pyrolysis process. Experiments were conducted by using spent mushroom substrates as raw materials to prepare biochar at different temperature intervals (300 to 600 °C). The addition of exogenous iron has been found to significantly enhance the carbon retention rate (12.2–44.5%) of biochar across various pyrolysis temperatures and, notably, improves the carbon stability of biochar at 300 °C, 400 °C, and 600 °C. Through the analysis of thermogravimetric mass spectrometry (TG-MS) and X-ray photoelectron spectroscopy (XPS), we discovered that iron catalyzes the thermochemical reactions and inhibits the release of organic small molecules (C2-C5) through both physical blocking (FexOx) and chemical bonding (C=O and O-C=O). The results of Raman spectroscopy and infrared spectroscopy analyses indicate that the addition of iron significantly promotes the graphitization process of carbon and enhances the thermal stability of biochar within the temperature range of 300 to 500 °C. When exploring the retention and stability of carbon during pyrolysis, it was found that under the conditions of 600 °C and the presence of iron, the maximum carbon sequestration rate of biochar can reach 60.6%. Overall, this study highlights the critical role of iron and pyrolysis temperature in enhancing the carbon sequestration capacity of biochar.

Electron-impact ionization of Si IV-VIII in hot plasmas

Abstract In this work, we investigate the ionization of silicon by electron impacts in hot plasmas. Our calculations of the cross sections and rates rely on the Coulomb-Born-Exchange, Binary-Encounter-Dipole and Distorted-Wave methods implemented in the Flexible Atomic Code (FAC), and are compared with measurements and other theoretical values. We use a semi-empirical formula for the cross section, which involves a small set of adjustable parameters. The rate coefficient is then expressed in terms of these parameters and is represented in a large temperature interval, up to 108 K. As expected, the agreement with measurements improves for increasing ion charges, confirming the applicability of our approach to hot plasma studies such as inertialconfinement fusion, and its reliability. Configuration interaction is taken into account and is shown to affect the cross section at low energy, in particular for Si3+.

Service of refractories in the regenerator nozzle glass furnace

The exhaust flue gases in glass furnaces include products of gas combustion and charge degassing, as well as products of evaporation from the glass melt. Of the main (CO2, H2O, N2 and O2) and secondary (Na, NaOH, Na2SO4, NaCl, HCl and SO2) smoke components for the service of refractories in the regenerator nozzle, sodium sulfate is the most problematic. The change in the aggregate state of gaseous Na2SO4 during the smoke cooling process gives rise to the release of two zones in the middle part of the nozzle: condensation and crystallization of sodium sulfate. Specifying the temperature intervals within which condensation (1100‒880 °C) and crystallization (880‒725 °C) of sodium sulfate occur allows us to formalize the technical conditions for the design of nozzles for single-turn and multi-turn regenerators of glass furnaces.

Effects of different tillage methods on soil properties and maize seedling growth in alternating wide and narrow rows rotation mode in the Songliao Plain of China

The Songliao Plain is the main maize (Zea mays L.) producing region in Northeast China. The no-tillage22NT: no-tillage. (NT) method in alternating wide and narrow rows rotation mode is widely used for maize planting in this region. However, in spring, the NT method in this mode suffer from low soil temperature and high soil water content33SWC: soil water content. (SWC), which severely restrict maize seed germination and seedling growth. We pioneered the research and practice of the ridge tillage44RT: ridge tillage. (RT) method and strip tillage55ST: strip tillage. (ST) method in this mode. We developed a new tillage machine to enable the implementation of RT and ST methods in alternating wide and narrow rows rotation mode, which has not been previously reported in this region. In this mode, the relative research of the RT method and ST method has not been conducted, and the effects of the RT method and ST method on the soil properties and maize seedling growth have not been clarified. Therefore, a 3-year field experiment was conducted at 7 randomly selected experimental sites in this region to research the effects of RT, ST, and NT methods on soil properties and maize seedling growth. During the spring sowing period, for soil pH, organic matter66OM: organic matter. (OM), available nitrogen, available phosphorus, and available potassium, both the RT method and ST method resulted in greater values than the NT method, and there was no significant difference between the RT method and ST method. This indicated that prolonged NT was not conducive to even distribution of OM, resulting in slightly lower available nitrogen, phosphorus, and potassium compared to the RT and ST methods. Within 30 days after spring sowing, for soil temperature, RT method value > ST method value > NT method value; for SWC, NT method value > RT method value > ST method value. For mean seedling emergence time77MET: mean seedling emergence time. (MET), RT method value < ST method value < NT method value; for seedling emergence rate88ER: seedling emergence rate. (ER), plant height, stem thickness, and plant dry weight, RT method value > ST method value > NT method value. Higher soil temperature, more suitable SWC, and better nutrient availability were beneficial in shortening MET, promoting dry matter accumulation, which ultimately increased plant height, stem thickness, and plant dry weight of maize seedlings. In RT, ST, and NT methods, soil temperature and plant dry weight were positively and linearly correlated in the 10–22 °C soil temperature interval. In the RT method and ST method, SWC and plant dry weight were positively and linearly correlated in the 15–24 % SWC interval. In the NT method, SWC and plant dry weight were negatively and linearly correlated in the 27–35 % SWC interval. Moreover, maize yield responses were positive for the RT method and ST method compared with the NT method. The RT method and ST method well solved the problems of low soil temperature and high SWC that existed in NT fields, which affected the early growth of maize seedlings, and ensured the stability and improvement of maize yields. The results suggest that both the RT method and ST method may provide significant improvements over the existing NT method.

Similar freezing spectra of particles in plant canopies and in the air at a high-altitude site

Abstract. Plant canopies are an important source of biological particles aerosolized into the atmosphere. Certain aerosolized microorganisms are able to freeze slightly supercooled cloud droplets and therefore affect mixed-phase cloud development. Still, spatiotemporal variability of such biological ice-nucleating particles (INPs) is currently poorly understood. Here, we study this variability between late summer and leaf shedding on the scale of individual leaves collected about fortnightly from four temperate broadleaf tree species (Fagus sylvatica, Juglans regia, Prunus avium and Tilia platyphyllos) on a hillside (Gempen, 650 m a.s.l. (metres above sea level)) and in a vertical canopy profile of one Fagus sylvatica (Hölstein, 550 m a.s.l.) in north-western Switzerland. The cumulative concentration of INPs active at ≥-10 °C (INPs−10) did not vary significantly between the investigated tree species but, as inferred from leaf mass per area and leaf carbon isotopic ratios, seemed to be lower on sun leaves as compared with shade leaves. Between August and mid-November, the median INP concentration increased from 4 to 38 INP−10 cm−2 of leaf area and was positively correlated with mean relative humidity throughout 24 h prior to sampling (Spearman's r=0.52, p&lt;0.0001, n=64). In 53 of the total 64 samples collected at the Gempen site, differential INP spectra between −3 and −10 °C exhibited clearly discriminable patterns: in 53 % of the spectra, the number of additionally activated INPs increased persistently with each 1 °C decrease in temperature; the remaining spectra displayed significant peaks in differential INP concentration above −9 °C, most frequently in the temperature interval between −8 and −9 °C (21 %) and between −7 and −8 °C (17 %). Interestingly, the three most frequent patterns in differential INP spectra on leaves in Gempen were also prevalent in similar fractions in air samples with clearly discriminable patterns at the high-altitude Jungfraujoch site (3580 m a.s.l., Switzerland) collected during summer in the previous year. These findings corroborate the idea that a large fraction of the airborne biological INP population above the Alps during summer originates from plant surfaces. Which parameter or set of parameters could affect biological INP populations on both scales – upwind airsheds of high-altitude sites as well as individual leaves – is an intriguing question for further exploration. A first guess is that leaf wetness duration plays a role.

Automatic optimization combined with genetic algorithm and CFD for temperature uniformity of OLED glass substrate

The heating technology and temperature uniformity of glass substrate (GS) are crucial for the final display quality and efficiency of OLED. In a high-temperature and large heating environment with mutual influences among multiple variables, maintaining temperature difference of the entire GS below 3 °C presents a complex combinatorial optimization problem in industrial manufacturing. To address this challenge, an automatic combined method is established. This method involves parameterized modeling in UG, thermal calculation in CFD, and genetic algorithm optimization in Matlab to determine optimum designs for electric heating tube (EHT) heating temperature and interval with respect to objective functions of temperature uniformity and highest temperature. Through this automatic combined optimized scheme, the optimized heating temperature and EHT interval have been achieved to ensure maintaining a temperature difference of entire GS within 3 °C. All simulations are validated by experiments with an error below 10 %, especially below 1 % under multi EHTs. A heating scheme of 13 EHTs with a radius 6 mm, a distance 5 mm, a temperature 390 °C and an uniform interval 38.5 mm is suggested after final optimization. It is hoped that this study can advance heating technology of OLED GS to achieve the desired practical level.

Heat Capacities of α-, β-, and γ- Polymorphs of Glycine.

As a part of our effort to establish reliable thermodynamic data for amino acids, the heat capacity and phase behavior are reported for two stable polymorphs (α and γ) of glycine (aminoacetic acid, CAS RN: 56-40-6). Prior to heat capacity measurement, thermogravimetric analysis and X-ray powder diffraction were performed to determine decomposition temperatures and initial crystal structures, respectively. The literature heat capacities obtained by adiabatic calorimetry are available in the temperature interval (7-304). The literature data were used for validating performance of our relaxation (heat-pulse) calorimeter, which was used for measurement of the heat capacity of α-glycine in the temperature interval (2-267) K. The crystal heat capacities of the α- and γ-glycine were extended towards higher temperatures using Tian-Calvet calorimetry in the temperature interval (262-358) and power compensation DSC in the temperature interval (310-449) K. As a result, reference heat capacities and thermodynamic functions for the crystalline phase from 0 K up to 450/435 K for α/γ-glycine were developed. The literature heat capacities for β-glycine over the range 0 K to 295 K were treated in the same manner in order to provide thermodynamic data for all three polymorphs existing at the atmospheric pressure.

Effect of sustained elevated temperature on compression and split-tensile properties of concrete made with waste foundry sand

PurposeThe aim of the current study is to inspect the influence of high temperatures on the compressive and split-tensile-strength (STS) of concrete mixtures produced by replacing natural river sand with waste-foundry sand (WFS) at 25%, 50%, 75% and 100%. When the experimental findings and the projected outcomes were compared by IS:456-2000 code equations, the STS results predicted by the suggested mathematical equations exhibit lower variations. It is proposed to employ the presented mathematical formulas to evaluate the STS of concrete cylindrical specimens at higher temperatures.Design/methodology/approachAfter fabricating, concrete mixtures were allowed to cure for 28 days. For the purpose of avoiding explosive spalling during the heating process, concrete samples are taken out from the curing chamber after 28 days and allowed to dry for two days. The manufactured concrete specimen is exposed to 100 °C, 200 °C, 300 °C, 400 °C, 500 °C and 600 °C temperatures for a duration of 2 h. After the specimens have cool down to room temperature (RT), the physical test, ultrasonic-pulse-velocity (UPV) test, compressive strength test and STS test are carried out.FindingsWith an increase in WFS content, concrete specimens' residue compressive-strength and STS decreases. The STS of samples declines as the WFS content rises with increase in temperature interval. According to the UPV test, the concrete samples quality is “good” up to 400 °C; after 500 °C, it ranges from “doubtful to poor.” The UPV values of various mixes declined as the temperature increased. Mass losses increase with exposure to greater temperatures and with an increase in the proportions of WFS in concrete specimens. For mixtures MWFS-0, MWFS-1, MWFS-2, MWFS-3 and MWFS-4 (0%, 25%, 50%, 75% and 100% WFS content), no cracks were present on any of the samples below 400 °C. Concrete surfaces start to show cracks whenever the intervals of temperature increase above 400 °C.Originality/valueIn this investigation, WFS elements are totally substituted for natural sand in concrete mixtures. The residue strength properties, including residual compressive strength and residual STS, were found to be lower after exposures to greater temperature when comparisons were made to referral mixtures. When comparing specimens’ compressive strength, higher temperatures have more effects on the STS of samples with higher WFS contents.

An experimental study on monitoring and early warning of spontaneous coal combustion fires using CPM

At present, the conventional indicator gas has a blank temperature interval in the monitoring of coal spontaneous combustion fire area, and the monitoring accuracy is easy to be interfered by wind flow, which leads to the inaccurate grasp of the situation of the fire area. To solve this problem, the characteristics of condensable particulate matter (CPM) released into the air during spontaneous combustion and heating are analyzed in this paper through a particle collection system. The results showed that the CPM captured by the system gradually increased when the coal temperature rose above 250℃, and the diameter was above 1um. After 300℃, the release of CPM increased significantly, which was more than 10 times that below 300℃. Test analysis showed that these CPMs were mainly phenols and polycyclic aromatic hydrocarbons, which accounted for 22 % and 37 % respectively after 300℃. CPM mainly comes from the pyrolysis stage and the early stage of combustion of coal. Aliphatic macromolecules and polycyclic aromatic compounds generated by pyrolysis are the precursors of CPM. Due to the limitation of oxygen diffusion, these compounds are released into the air due to insufficient oxidation and eventually form CPM. It is worth noting that the release amount and composition of CPM have a good correspondence with coal temperature. The research results can fill the temperature gap of monitoring fire situation by conventional gas, and help to improve the accuracy of monitoring, which is of great significance for the protection of coal resources and safe production.

Copper based high temperature heat storage macrocapsules with optimized inner cavity

The development of practical high temperature metallic phase change macrocapsules still faces difficulties, because metallic phase change materials undergo volume expansion during phase transformations, which can lead to outer shell rupture. When a core made of stacked metal powders is used, a cavity is eventually formed inside the capsule that acts as a cushion for volume expansion, thus reducing the risk of capsule rupture. However, the cavity will weaken the thermal storage capacity of the capsule, and in order to obtain a capsule with good thermal storage capacity and long-time cycling stability, it is necessary to find a suitable cavity volume of the capsule. In this paper, Cu powders are used as the core raw material, which are spherelized into millimeter level spheres, and the Cu powder spheres are isostatically pressed using an isostatic presser under different pressures to achieve the optimization of the cavity volume by reducing the gap between the powders. The high strength α-Al2O3 is selected as the shell, and sintering additives MgO and SiO2 are doped into the raw material, and the Cu@MgO-SiO2/Al2O3 capsules are prepared after two-step sintering treatment. The material properties and thermal storage properties of the capsules are investigated in detail, which have strong thermal storage properties, for example, in the temperature interval of 1000–1100 ℃, capsules with a core-shell structure (named as 9@1.5–100 MPa, prepared with initial diameter of Cu core of 9 mm, shell thickness of 1.5 mm, and isostatic pressing under 100 MPa to the core precursor) exhibit a high heat storage density of 222 J/g and 841 MJ/m³. In addition, we conduct melting-solidification cycle tests, which confirms the excellent durability of the capsules. The comprehensive results show that the Cu@MgO-SiO2/Al2O3 macrocapsules possess strong thermal storage capacity and can be used as effective thermal storage materials, especially in advanced high temperature thermal storage systems.

Experimental determination of the coefficient of viscosity of the dry snow

Snow compaction is a natural process in the evolution of any snow cover, and this obviously changes the physical and mechanical properties of a snow thickness. The quantitative estimate of this process is a coefficient of the snow viscosity, which is linearly related to the rate of the snow cover deformation The technique for preparation and testing of samples with the fine-grain snow under condition of uniaxial compression at negative temperatures is described. It was determined that values of the snow viscosity coefficient fall within the range from 0.10 to 0.30 g/cm³ for three temperature intervals. The viscosity coefficient of the fine-grain snow varies from 10⁸ до 10¹⁰ Па. The data obtained made possible to find the limits of variability of this coefficient for winter conditions on the Russian plain. A dependence of the viscosity coefficient on the snow density and temperature is proposed, and it describes the series of the above shown experimental data. It is shown that influence of changes in the viscosity coefficient of fine-grain snow on the snow properties depending on its density are comparable in scale to the influence of the temperature. The result may be useful for modeling the evolution of snow cover.

A Study of the Effect of Temperature on the Capacitance Characteristics of a Metal-μhemisphere Resonant Gyroscope.

Metal-μhemispherical resonant gyros (M-μHRGs) are widely used in highly dynamic navigation systems in extreme environments due to their high accuracy and structural stability. However, the effect of temperature variations on the capacitance characteristics of M-μHRGs has not been fully investigated, which is crucial for optimizing the performance of the gyro. This study aims to systematically analyze the effect of temperature on the static and dynamic capacitances of M-μHRGs. In this study, an M-μHRG structure based on a 16-tooth metal oscillator is designed, and conducted simulation experiments using non-contact capacitance measurement method and COMSOL Multiphysics 6.2 finite element simulation software in the temperature range of 233.15 K to 343.15 K. The modeling analysis of the static capacitance takes into account the thermal expansion effect, and the results show that static capacitance remains stable across the measured temperature range, with minimal effect from temperature. The dynamic capacitance exhibits significant nonlinear variations under different temperature conditions, especially in the two end temperature intervals (below 273.15 K and above 313.15 K), where the capacitance values show local extremes and fluctuations. In order to capture this nonlinear behavior, the experimental data were smoothed and fitted using the LOESS method, revealing a complex trend of the capacitance variation with temperature. The results show that the M-μHRG has good capacitance stability in the mid-temperature range, but its dynamic performance is significantly affected at extreme temperatures. This study provides a theoretical reference for the optimal design of M-μHRGs in high- and low-temperature environments.

Coupled reactions in the system SrO–BaO–Al2O3–SiO2

Progress in the field of aircraft construction is usually determined by the functional capabilities of those materials that are used for the creation of aircraft equipment. Compositions of celsian-slawsonite ceramics belonging to the BaO–SrO–Al2O3–SiO2 oxide system are promising for use in the aircraft industry due to their high operational properties. In this regard, a theoretical study of its subsolidus structure is of great interest. The paper presents the results of calculating the Gibbs free energy for coupled reactions in the selected multicomponent system. The temperature intervals of the coexistence of phase combinations are given and the formed elementary tetrahedra are constructed. According to the results of theoretical studies, it is established that the considered multicomponent system is divided into 28 elementary tetrahedra. The existence of a combination of Sr2Al2SiO7–2SrSiO3–BaSiO3 phases in the temperature range of 300–700 K is confirmed, a "filled triangle" being formed between them. Based on the results of thermodynamic calculations, it is established that the reaction between Ba2SiO4 and SrAl2Si2O8 phases does not occur at temperatures up to 1200 K, and it is thermodynamically possible in the range of 1200–1700 K with the formation of a combination of BaSiO3–BaAl2O4–Sr2Al2SiO7 phases, which form a "filled circuit".

The exploration of effect for nano-Al2O3 on solid waste based superfine tailings cemented paste backfill: Pyrolysis property, hydration mechanism and environmental risk

Resource utilization of superfine tailings has become a key research direction in filling mining. This study analyzes the mechanical properties, pyrolysis mechanism and hydration mechanism of nano-Al2O3(NA)-doped solid waste based superfine tailings cemented paste backfill (SWSCPB) by multiple microscopic characterization methods and pyrolysis kinetic theory. The results show that the main temperature interval for the pyrolysis of SWSCPB to happen is 280–900 °C, which is divided into two stages of dehydroxylation and decarbonization. The apparent activation energy(E) and pre-index factor(A) of pyrolysis are higher than those of NA0 and NA2 at 1 % NA dosage, indicating that NA increases the energy barrier of pyrolysis, the percentage of activated molecules, and the collision probability of hydration products in SWSCPB, but decreases due to agglomeration at exceeds 1 % NA dosage. NA can enhance macroscopic strength of SWSCPB, with the highest strength at 1 % NA dosage. Compared with NA0 and NA2, more hydration products such as AFt and C-(A)-S-H are present in NA1, and the distribution of Q2 and Q4 in C-(A)-S-H is more pronounced, with a higher degree of polymerization, a stronger tendency for the conversion of non-bridging to bridging oxygen bonds, and fewer pores in the microstructure of SWSCPB. The NA dosage can provide more nuclei for the formation of AFt, C-(A)-S-H in SWSCPB, and can also promote the replacement of Si by Al for the conversion of C-S-H to C-(A)-S-H with higher polymerization. In addition, the leaching risk and mechanism of heavy metal ions from SWSCPB are preliminarily explored in combination with leaching experiments. The results provide new insights and guidance for the application of SWSCPB in filling mining under cleaner production targets.

Two-step preparation and characterization of Bi-2212 superconductors by the glycine-nitrate method

In order to prepare high-quality sub-stable copper oxide superconductor Bi-2212, the glycine-nitrate method combined with rapid sintering process was used in this paper. Firstly, the glycine-nitrate method was used to obtain highly active Bi-2212 precursor powders with uniform composition, and then Bi-2212 superconductor powders were prepared by rapid sintering. Glycine acted as a combustion agent while giving property of the complexation to ensure the homogeneity of multiple chemical components. The high-quality precursor powder was the basis for broadening the temperature interval of the pure phase of Bi-2212. And then the effects of precursor powder sampling pressure on Bi-2212 superconducting materials were systematically investigated. On this basis, the pure-phase temperature interval of Bi-2212 superconducting materials prepared by the nitroglycerin method was further investigated. The results showed that the increase of the sample preparation pressure can effectively optimize the crystallinity of Bi-2212, which no longer changed significantly after 300MPa. The pure phase temperature interval of Bi-2212 was 830~880 °C. The samples showed the characteristic lamellar morphology. The optimum sintering temperature was 850°C. The crystal integrity of Bi-2212 was destroyed under high temperature sintering conditions, and the two-dimensional properties were enhanced. The superconducting properties of Bi-2212 were acceptable, with a Tc, onset of 82.1K, Tc, zero of 72.4K, and ΔTc of 9.7K. This work largely reduces the difficulty in the preparation of the superconductors of Bi-2212, and it provides a good basis for the preparation of multi-component functional oxides by using the nitrate method.

From thermal demand characterization to accurate evaluation: Exploring seasonal differences in outdoor thermal comfort of the elderly in China's communities

Influenced by rapid urbanization and an aging population, creating a healthy and comfortable outdoor environment for the elderly in urban residential communities has become increasingly important. This paper aims to investigate the outdoor thermal comfort characteristics of the elderly, using residential communities in Tianjin, China, as a case study. Initially, we clarified the differences in thermal demand between winter and summer of elderly residents through a combination of thermal environment measurements and thermal comfort questionnaires. Secondly, we developed a thermal comfort evaluation model for small-scale spaces in residential communities, identifying the intensity of multiple influences on the thermal environment. Thirdly, we created a new seasonal integrated thermal sensation evaluation model for the elderly using probit analysis. Finally, summarizing the above findings, we devised targeted strategies to enhance the microclimate for the elderly. The results show that: the percentage of the elderly who achieve comfort in winter is 17.2 % higher than in summer; the factors that had the greatest impact on the thermal environment in winter and summer were water bodies and greenery, respectively; and the new probability analysis model showed that the neutral temperature interval was 2.1 °C narrower than the conventional TSV-PET model in summer and 1.8 °C wider in winter.

Domestic hot water systems in well-insulated residential buildings: A comparative simulation study on efficiency and hygiene challenges

Domestic hot water (DHW) is essential for daily life, yet the production can be energy intensive. Advances in building insulation reduced space heating demand, while DHW energy demand remained constant or even increased. The need for a higher proportion of renewable heat amplifies the conflict in DHW systems between energy efficiency, hygiene, and comfort, since high temperatures are required for hygienic purposes. Thus, developing DHW systems efficiently utilising renewable heat without excessive temperature requirements is essential.This paper reviews efficiency and hygiene challenges in DHW systems and assesses proposed solutions through comparative simulations in well-insulated residential buildings.Results show higher efficiencies in decentralised than centralised DHW systems. However, even in decentralised systems the necessity for circulation is a significant limitation. Lowering DHW temperature or transitioning to decentralised systems significantly reduces final energy demand, improves heat pump performance and increases the renewable heat share. Reducing DHW temperature from 60 to 50 °C increases stagnation periods in lower temperature intervals (22–34 °C) in warm water pipes.The study indicates significant potential to increase system efficiency and reduce final energy demand in decentralised or low-temperature DHW systems and introduces a novel method to compare conditions with regard to hygiene of DHW system simulations.

Microstrain partitioning, transformation induced plasticity, and damage evolution of a third generation medium Mn advanced high strength steel

An experimental Medium Mn (med-Mn) steel (0.15C-5.8Mn-1.8Al-0.71Si) with a martensitic starting microstructure, intercritically annealed at 685 °C for 120s, was discovered to have a large true strain at fracture (ɛf = 0.61) while also meeting established (strength x elongation) targets (28,809 MPa%), sustained monotonic work hardening and prolonged Transformation Induced Plasticity (TRIP) kinetics. This was found by varying the intercritical annealing (IA) temperature within a narrow temperature interval in order to isolate its impact on TRIP kinetics and damage development on such med-Mn steel. A comprehensive understanding of the microstructural damage processes leading to fracture is presented using quasi in-situ Scanning Electron Microscope tensile testing as well as X-ray Computed Microtomography. In addition, we precisely evaluated the TRIP kinetics of this steel using a combined Digital Image Correlation (DIC) and synchrotron-sourced High Energy X-ray Diffraction technique. With these methods, we demonstrate that an abundance of voids nucleate during deformation, but their growth can be suppressed by prolonging TRIP over a large strain range. Moreover, novel post-processing techniques to assess DIC acquired data at the microscopic scale have been used to gauge the severity of strain partitioning amongst phases and strain gradient evolution across dissimilar phase interfaces. By comparing it to another 3G TRIP-assisted steel and an ultrafine grained Dual Phase steel. Overall, it has been found that, in addition to carefully moderating TRIP kinetics, the introduction of polygonal ferrite, as is conventional in med-Mn steels, enhances the local forming properties and damage tolerance in 3G TRIP-assisted microstructures.

Spin-reorientation transition and exchange-bias effect in CeFe0.5Cr0.5O3 ceramics

The polycrystalline CeFe0.5Cr0.5O3 ceramics were synthesized by the solid-state method, whose structural and magnetic properties were systematically studied. With the interaction between Ce and Fe/Cr ions, a first-order spin-reorientation transition from Γ4 to Γ1 is observed over a wide temperature interval in CeFe0.5Cr0.5O3, which is remarkably sensitive to applied magnetic field. Interestingly, the exchange-bias effect is found in CeFe0.5Cr0.5O3 ceramics during the spin-reorientation transition, ascribed to the paramagnetic/antiferromagnetic system presented by the two interacting magnetic sublattices (Ce and Fe/Cr). The coexistence of spin-reorientation transition and exchange-bias effect is promising to expand the practical application of CeFe0.5Cr0.5O3 ceramics in multifunctional spintronics.

Simulation of stainless ferritic-martensitic and austenitic steel hardening after irradiation in ion accelerator. Part 2. Development of a methodology for determining the ion mode irradiation of austenitic steels

A methodology for determining the irradiation mode for ferritic-martensitic steels at ion accelerator has been developed and experimentally substantiated, providing radiation hardening of these steels, identical to that realized under neutron irradiation. The change in Vickers microhardness is used as a measure of radiation hardening. The paper presents the results of a study of radiation-induced changes in the microhardness of austenitic steels 08Kh18Н10Т and 08Kh16Н20М2Т irradiated in reactors SM-3, VVER-440, BOR-60, SM-3 + BOR-60 to damaging doses of 10.2–33.7 dpa in the interval of temperatures 60–500°C. A study of radiation-induced changes in microhardness in a wider range of irradiation temperatures, post-irradiation annealing of irradiated steels was carried out in the range from 400 to 600°C, simulating irradiation at temperatures equal to annealing temperatures. Data are presented on radiation-induced changes in microhardness after irradiation in the ion accelerator of the State Scientific Center of the Russian Federation – Institute for Physics and Power Engineering named after A.I. Leypunsky (IPPE) with Ni+4 ions and He+ ions up to concentrations of 0–7 appm/dpa at damaging doses of 13–30 dpa and temperatures of 300–650°. A transition function has been established that connects the irradiation of temperatures during neutron and ion irradiation at a given damaging dose, ensuring the same radiation hardening of austenitic steels.