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The process of glass transition during the quenching in the domain with the cold wall has been numerically simulated. We have implemented the temperature-dependent form of the previously proposed theoretical model, which combined the heat transfer in the domain and the gauge theory of glass transition, assuming the presence of topologically stable distortions (disclinations) in the forming solid. The competition between crystallization (formation of polycrystalline structure) and the formation of the amorphous disordered phase has been shown. At the relatively slow cooling rates corresponding to the formation of the crystalline phase, we observed a columnar to equiaxed transition qualitatively similar to the observed in many metallic alloys. The moving front followed the equilibrium isotherm corresponding to the equilibrium temperature of transition in the disclinations subsystem, although front drag resulted in the effect of kinetic undercooling and the emergence of the maximum velocity of the crystallization front. High thermal conductivity values associated with the substantial heat flux lead to the bulk amorphous state. The dynamics of the coarsening of the primary amorphous structure depended on the annealing temperature.

The martensitic transformations in Cu–38Zn and Cu–39.5Zn (wt %) alloys with the shape memory effect have been studied using a combination of transmission and scanning electron microscopy, optical metallography, and X-ray diffraction analysis. When examining specimen upon cooling to low temperatures in the transmission electron microscope column, the features of martensite morphology and fine structure, as well as of electron microdiffraction in the alloys, have been ascetained. The structural types of martensite phases (3R) and (2H) have been identified in Cu–38Zn alloys, as well as (9R) and (2H), in Cu–39.5Zn alloys. The proposed crystallographic models of martensitic rearrangement in the alloys are based on an analysis of X-ray and electron diffraction, including diffuse electron scattering, as well as on the packing defects of the internal substructure of martensite. [ABSTRACT FROM AUTHOR]

The effect of heat treatment on the structural evolution, phase transformation, and mechanical strength of Al–12Si obtained using wire electron beam additive manufacturing has been investigated. The as-built Al–12Si alloy was characterized by structural inhomogeneities in the form of interlayer bands with coarsened Si particles resulted from cyclic reheating of the solidified metal. Quenching the as-built samples resulted in the increase of the volume fraction of Al/Si eutectics by 9% with simultaneous refinement of Fe-containing particles. This structure allows obtaining the combination of strength and plasticity better than that of the asbuilt sample. Annealing leads to coarsening of both Si and Fe-containing particles, thereby increasing the Al/Si volume fraction and impairing the mechanical characteristics. [ABSTRACT FROM AUTHOR]

When a suitable balance of hardness, strength, and toughness is required in civil engineering and construction, wear-resistant medium carbon steels are frequently utilized. The ability to resist plastic deformation brought on by stress or abrasion is measured by hardness. High hardness materials are typically more brittle and prone to fracture but also stronger and more resistant to corrosion. A double-quenching procedure was used in the current investigation and contrasted with the traditional single-quenching process. Additionally, a variety of cooling media are used during quenching treatments. The results demonstrate that distilled water is the most effective cooling medium to cool the models in the heat treatment of medium carbon steels because it is free of salts, suspended particles, and metal contaminants. The results show that the hardness increased following the first quenching and tempering by 37.5% above the hardness value predicted by the original model, and it increased once more following the second quenching and tempering by 10% over the hardness value following the first heat-treatment. The previous austenite grain limits and the high-angle beam limits are the main factors that give a share in to the increased hardness, and the main elements that affect how effectively they function are the high slip transmission factor and the high spacing angle between slip levels. [ABSTRACT FROM AUTHOR]

In this paper, enhancing the tribological characteristics of novel cast metallic materials—hybrid multi-component cast irons—by applying a strengthening heat treatment is described. The experimental materials were the cast alloys of a nominal composition (5 wt.% W, 5 wt.% Mo, 5 wt.% V, 10 wt.% Cr, 2.5 wt.% Ti, Fe is a balance) supplemented with 0.3–1.1 wt.% C and 1.5–2.5 wt.% B (total of nine alloys). The heat treatment was oil-quenching followed by 200 °C tempering. The quench temperature (QT) varied in the range of 900–1200 °C, with a step of 50 °C (with a 2-h holding at QT). The correlation of the QT with microstructure and properties was estimated using microstructure/worn surface characterization, differential scanning calorimetry, hardness measurement, and three-body-abrasive wear testing (using Al2O3 particles). The as-cast alloys had a multi-phase structure consisting of primary and/or eutectic borocarbide M2(B,C)5, carboborides M(C,B), M7(C,B)3, M3(C,B), and the matrix (ferrite, martensite, pearlite/bainite) in different combinations and volume fractions. Generally, the increase in the quenching temperature resulted in a gradual increase in hardness (maximally to 66–67 HRC) and a decrease in the wear rate in most alloys. This was due to the change in the phase-structure state of the alloys under quenching, namely, the secondary carboboride precipitation, and replacing ferrite and pearlite/bainite with martensite. The wear rate was found to be inversely proportional to bulk hardness. The maximum wear resistance was attributed to QT = 1150–1200 °C, when the wear rate of the alloys was lowered by three to six times as compared to the as-cast state. With the QT increase, the difference in the wear rate of the alloys decreased by three times. The highest abrasive resistance was attributed to the alloys with 1.1 wt.% C, which had a 2.36–3.20 times lower wear rate as compared with that of the reference alloy (13 wt.% Cr cast iron, hardness of 66 HRC). The effects of carbon and boron on hardness and wear behavior are analyzed using the regression models developed according to the factorial design procedure. The wear mechanisms are discussed based on worn surface characterization. [ABSTRACT FROM AUTHOR]

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

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

The process of glass transition during the quenching in the domain with the cold wall has been numerically simulated. We have implemented the temperature-dependent form of the previously proposed theoretical model, which combined the heat transfer in the domain and the gauge theory of glass transition, assuming the presence of topologically stable distortions (disclinations) in the forming solid. The competition between crystallization (formation of polycrystalline structure) and the formation of the amorphous disordered phase has been shown. At the relatively slow cooling rates corresponding to the formation of the crystalline phase, we observed a columnar to equiaxed transition qualitatively similar to the observed in many metallic alloys. The moving front followed the equilibrium isotherm corresponding to the equilibrium temperature of transition in the disclinations subsystem, although front drag resulted in the effect of kinetic undercooling and the emergence of the maximum velocity of the crystallization front. High thermal conductivity values associated with the substantial heat flux lead to the bulk amorphous state. The dynamics of the coarsening of the primary amorphous structure depended on the annealing temperature. [ABSTRACT FROM AUTHOR]

The low-carbon steel revealed the presence of ferrite-pearlite and ferrite-martensite microstructures after being subjected to different thermomechanical routes. These routes involved two distinct stages: 1) reheating hot-rolled steel at 1473 K, followed by cooling via step quenching, intermediate quenching, and furnace cooling, and 2) cold rolling and subsequently annealing at 873 K for 2 and 8 h. The quenching schedules finally developed a ferrite-martensite structure with different martensitic morphology, whereas furnace cooling promotes a ferrite-pearlite structure. The prolonged annealing assists in carbide precipitation from deformed ferrite-martensite microstructure while pre-existing carbides coarsen after 8 h of annealing in furnace-cooled specimens. The sudden phase disintegration contributes to the changes in the recrystallized kinetics and evolution of precipitates, tailoring the final grain size. Additionally, the development of textures after cold rolling and annealing is studied through the emergence of α and γ fiber in BCC phase. Finally, detailed microscopic technique has been employed to correlate the overall tensile response of the investigated samples with their interrelated microstructures. [ABSTRACT FROM AUTHOR]

This paper addresses the combustion of ammonium perchlorate (AP) near adiabatic conditions at high pressures and higher initial temperatures. The AP pellets were coated with a thin layer of silica grease to simulate the near adiabatic condition. The experiments were performed at initial temperatures of 30 and 70 °C in the pressure range of 2.5–30 MPa for coated and bare pellets. The bare pellets were found to exhibit mesa burning as reported in the literature. However, the coated pellets did not exhibit mesa burning. The burn rates of coated AP pellets increased linearly for the entire pressure range of 2.5–30 MPa with 0.64 pressure index. Further, the experiments were carried out for the first time at an initial temperature of 90 °C for 14–30 MPa pressure range, wherein, AP combustion did not display any characteristics of mesa burning (pressure index of 0.33). The surface morphology of quenched samples of both bare and coated pellets of AP were studied, by quenching (rapid depressurization technique) pellets at 6, 12, and 18 MPa pressures. The surface structure of quenched samples for near adiabatic conditions was similar for all three pressures. However, for bare pellets the changes in surface structure were observed with change in pressure, similar to the literature. Mesa burning was found to be an effect of convective heat loss from the periphery of the pellets and it was not observed when heat loss was reduced or initial temperature was higher than the critical initial temperature. [ABSTRACT FROM AUTHOR]

A single-photon avalanche diode (SPAD) is a photon-counting sensor renowned for its exceptional single-photon sensitivity. One significant feature of SPADs is their non-linear response to light, making them ideal for high-dynamic range imaging applications. In SPAD imaging, the photon detection mode, which depends on the quenching method employed, is crucial for optimizing image quality and dynamic range. This paper examines the free-running and gating imaging modes, evaluating their impacts on photon capture and saturation limits. Given that the number of incident photons follows a Poisson distribution, we introduce an innovative imaging-quenching model based on statistical mathematics. We designed and fabricated two SPAD imaging sensors using 180 nm CMOS technology. Image processing and evaluation were conducted using a mapping method. Our results show that in low-light conditions, the gating mode surpasses the free-running mode in the signal-to-noise ratio (SNR). However, the free-running mode exhibits a saturation limit of more than an order of magnitude higher than that of the gating mode, demonstrating its superior capability to handle a broader range of light intensities. This paper provides a thorough analysis of the differences between the two imaging methods, incorporating the theoretical mathematical model, circuit characteristics, and computed imaging quality. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

CsPbX 3 (X = Cl/Br, Br, Br/I, I) perovskite quantum dots (QDs) glasses have enormous application potential in the field of long wavelength pass (short wavelength cutoff) filters. In this work, the CsPbX 3 (X = Cl/Br, Br, Br/I, I) QDs doped with Se4+ were prepared in the borogermanate glass matrix. To quench strong exciton emission of QDs, the CsPbX 3 (X = Cl/Br, Br, Br/I, I) perovskite QDs glasses were doped with Se4+ at different concentrations of 0, 0.05 %, 0.1 % and 0.2 %, respectively. The nanocrystal structure, transmittance, optical density, photoluminescence (PL), PL excitation and PL decay have been investigated. The working wavelength of filters has been extended to wide range from 440 nm to 650 nm. The samples have large optical density in cutoff region, excellent steepness in the transition region, and high transmittance in transmission region. As Se4+ concentration increases, the PL intensity is quenched and the PL lifetime is decreased obviously for CsPbX 3 QDs glasses, whereas the absorption and transmittance characteristics for filters are less affected. The quenching mechanism is attributed to nonradiative recombination by deep energy level traps. The Se4+ doped CsPbX 3 QDs glasses can meet requirements for the long wavelength pass filters. [ABSTRACT FROM AUTHOR]

Initially, a brief historical review related to the discovery of iron is made. Studies of artifacts such as tools blades and weapons from more than 1000 years BC, allowed us to conclude that the knowledge already existed to increase the hardness of metals, both due to the increase in carbon content and sudden cooling from high temperatures (a process called tempering or hardening). This suggests that there was a considerable degree of sophistication on the part of these early blacksmiths. Next, the basics of materials theory and formation of the crystalline structure of iron- carbide iron (Fe-Fe3C) based on the phase diagram are presented. Modernly, materials science has shown that increasing temperature changes the atomic structure of ferrite (pure iron with BCC structure) to austenite (FCC), which allows the inclusion of other elements, such as carbon, for example. The quenching process, on the other hand, abruptly changes the atomic structure from austenite to martensite (BCT), keeping the carbon attached to the final structure, giving the new material a significant increase in hardness. Although the context of the article is, at first glance, historical, the controlled heat treatment of steel is essential for the modern world and is used to ensure that it has the desired properties in industry in general. [ABSTRACT FROM AUTHOR]

Solid solution strengthened ferritic ductile iron proves to have a better ratio of tensile strength to elongation than conventional ductile iron grades. This applies up to a maximum silicon content of 4.3 wt%, beyond which it leads to an abrupt decrease in ultimate tensile strength and elongation at fracture. During solidification of high silicon ductile iron, negative segregation of silicon occurs, and the highest silicon concentration is observed near the graphite nodules. This high silicon concentration leads to long-range ordering of iron and silicon, and this ordering results in formation of superstructures like BCC_B2 and D03. The presence of super structures restricts the mobility of dislocations and leads to abrupt fracture of the material. This research focuses on the investigation of silicon homogenization by the addition of aluminium and heat treatments to avoid the formation of brittle iron–silicon superstructure. Thermodynamic–kinetic simulations as well as experimental investigations, including variation in alloy composition and quenching, are performed. The results provide a promising understanding to control the micro-segregation of silicon in ductile cast iron based on heat treatments and alloy composition. [ABSTRACT FROM AUTHOR]

The process of transition from the liquid to the solid state during the uniform quenching is described by a combination of two theoretical approaches: the phase field method and the gauge theory, which suggests the phase transition in the subsystem of topologically stable distortions. Using the stochastic partial differential equations we numerically simulate competition between the processes of crystallization and vitrification during the rapid cooling of the melt. A glass order parameter which is suitable for the characterization of transition to the glassy state has been proposed. At low cooling rates, the domain freezes into the crystalline structure with defects, and its glass order parameter is orders of magnitude less than that for the vitrified state obtained by rapid quenching. Proposed method improves and extends the theoretical description of glass transition, qualitatively represents the basic kinetic properties of the process and demonstrates sensitivity of resulting microstructures to the quenching rate. [ABSTRACT FROM AUTHOR]

Biochar is one of the most important carbon-rich minerals with a porous structure in the carbon sequestration, immobilization of metal and organic contaminants, as well as soil fertility improvement. However, its large-scale use is very limited in the agriculture and environment, due to the high cost of production and transportation from agricultural biowaste to plant. In this study, a new technology was explored to directly convert from agricultural biowaste to biochar in the field. The local applications had significantly reduced the costs of biochar. Inspired by nature, biochar production was also proposed in the field, where only agricultural biowaste, water, and fire were required for biomass carbonization and charcoal formation; Specifically, Litchi branches sourced from subtropical regions were utilized as feedstock to explore an on-site production of biochar. Soil (Ferralsols) slurry was applied as a coating and quenching agent to create an oxygen-limited environment during fire-water coupled carbonization of the feedstock. This self-limiting oxidation approach was used to minimize the expenses of production, transportation, and utilization. Biochar that was produced with soil slurry coating and quenching also displayed the highest carbon content (83.5%) and carbon capture capacity (83.9%), exceeding unconverted biomass and biochar produced without coating by 16.7% and 37.8%, respectively. The burning process of Litchi branches was divided into three stages: 1) Surface was charred immediately but with an unburned core; 2) Surface was grayed out, while the core was in a self-ignition state with high temperature and limited oxygen, and the dark red char fell to the ground; and 3) The dark red char gradually burned out to be ash. Spraying water on the dark red char was used to prevent the occurrence of the 3rd stage, thus favoring the formation of biochar instead of ash. Furthermore, the soil coating likely acted as a barrier, thus reducing carbon monoxide or carbon dioxide release during combustion. Additionally, the soil integration was facilitated to form the mineral-carbon composite for the carbon capture. Scanning electron microscopy and energy spectroscopy analysis show that the regular structure of the carbon skeleton was observed after coating and quenching the iron-aluminum slurry. The iron-aluminum minerals were also loaded on the surface. A novel approach to carbonization accelerated a paradigm shift in biochar production from a sophisticated stationary facility to a simple way for practical use in the field. Low cost greatly contributed to the agricultural and environmental application of biochar. The economically viable combination of fire and soil (Ferralsols) slurry coupled carbonization can be expected to provide valuable insights for biochar adoption and carbon neutrality. In conclusion, the readily available agricultural residues and soil-based coatings can be integrated to mitigate the environmental impact of biochar production, in order to enhance the efficacy as a carbon capture. These findings can offer significant implications for the broader adoption of biochar as a sustainable solution, in order to promote climate and soil health. [ABSTRACT FROM AUTHOR]

Sodium bismuth titanate‐based materials are expected to be an alternative candidate to lead‐based ceramic materials due to their excellent electrical properties. However, the low depolarization temperature (Td) limits their practical application. In this work, the phase structure evolution and microstructure of 0.9(0.4Na1/2Bi1/2TiO3–0.6BiFeO3)–0.1BaTiO3: xZnO (x = 0.01, 0.03, 0.05, and 0.07) (abbreviated as 100xZnO) composite ceramics are investigated, and their piezoelectric properties are improved by combination of constructing 0–3 type composites and quenching treatment technology. The addition of ZnO can increase both Td and d33 because ZnO can enhance the lattice distortion of rhombohedral phase and lead to the increase in ferroelectric order. Specifically, the optimum composition x = 0.03 obtains the d33 value of 106 pC/N (25°C), which retains 84% of the value at room temperature up to 240°C. And the quenching technology further enhances the ferroelectric order and increases Td, which is up to 280°C for x = 0.03. [ABSTRACT FROM AUTHOR]

Methods of transmission and scanning electron microscopy are used to study premartenstic states and their relation to martensitic transformations in the alloys Cu–38 wt % Zn and Cu–39.5 wt % Zn with shape memory effect. Analysis of the observed diffusion scattering of electrons is carried out, including in situ experiments at heating and cooling and the defect condition of the internal substructure of austenite and martensite. The crystallographic models of martensitic transitions β2 → , β2 → , and β2 → are proposed based on the crystallographic data obtained in the premartensitic state. [ABSTRACT FROM AUTHOR]

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

In this study, an environmentally sustainable fluorimetric method for determination of Vonoprazan fumarate (VON) in dosage forms using nanoprobes consisting of nitrogen and sulfur co‐doped carbon quantum dots (N, S‐CQDs). The N, S‐CQDs were prepared through a microwave‐assisted method in 30 s. The resulting N, S‐CQDs were characterized using transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS). They exhibit fluorescence emission at 460 nm after excitation at 385 nm with a high quantum yield (60%). The analytical approach for VON determination relies on the quenching effect exerted by VON on the native fluorescence intensity of CQDs. The quenching mechanism was investigated using Stern–Volmer plots. The proposed method demonstrates linearity across a concentration range 10–80 μM (4.6–36.8 μg/mL) with corresponding limits of detection and quantitation calculated as 2.17 μM (0.99 μg/mL) and 6.58 μM (3.02 μg/mL), respectively. The method has been effectively utilized for the determination of VON in the pharmaceutical samples. Statistical comparison with reported RP‐HPLC has been performed to verify the accuracy and precision of the developed method. The environmental sustainability of the developed method has been thoroughly examined through various greenness metrics. [ABSTRACT FROM AUTHOR]

Mefenamic acid, renowned for its analgesic properties, stands as a reliable choice for alleviating mild to moderate pain. However, its versatility extends beyond pain relief, with ongoing research unveiling its promising therapeutic potential across diverse domains. A straightforward, environmentally friendly, and sensitive spectrofluorometric technique has been developed for the precise quantification of the analgesic medication, mefenamic acid. This method relies on the immediate reduction of fluorescence emitted by a probe upon interaction with varying concentrations of the drug. The fluorescent probe utilized, N‐phenyl‐1‐naphthylamine (NPNA), was synthesized in a single step, and the fluorescence intensities were measured at 480 nm using synchronous fluorescence spectroscopy with a wavelength difference of 200 nm. Temperature variations and lifetime studies indicated that the quenching process was static. The calibration curve exhibited linearity within the concentration range of 0.50–9.00 μg/mL, with a detection limit of 60.00 ng/mL. Various experimental parameters affecting the quenching process were meticulously examined and optimized. The proposed technique was successfully applied to determine mefenamic acid in pharmaceutical formulations, plasma, and urine, yielding excellent recoveries ranging from 98% to 100.5%. The greenness of the developed method was evaluated using three metrics: the Analytical Eco‐scale, AGREE, and the Green Analytical Procedure Index. [ABSTRACT FROM AUTHOR]

The new ligand 3,3′‐bis(((2‐(3,6,9‐triaza‐1(2,6)‐pyridinacyclodecaphane‐6‐yl)ethyl)amino)methyl)‐[1,1′‐biphenyl]‐2,2′‐diol (L) has been synthesized and characterized. It contains two pyridinacyclophane macrocycles spaced by a 2,2’‐biphenol moiety. The acid‐base behaviour of L as well as its binding properties towards Zn2+ ion have been investigated. This work is inserted in the field of fluorescent ditopic receptors, formed by two polyamines spaced by a aromatic fragments. This ligand represents a new example of a peculiar case of polyamine fluorescent receptor in which the interaction with Zn2+ is translated into a deactivation of the emission. Enough data to describe and explain this unusual behaviour was obtained through potentiometric, UV‐Vis, fluorescence and NMR titrations as well as theoretical calculations. This studies have shown that the metal cation is indirectly affecting the emission favouring a conformation in which the fluorophore is at stacking distance from the electron poor pyridine moieties. This gives rise to an oxidative photoinduced electron transfer from the excited state of the fluorophore to the electron‐poor Zn2+ coordined pyridine. [ABSTRACT FROM AUTHOR]

Geometric distortion is a common occurrence in the manufacturing of fragile structures, especially in thin-walled parts. Current numerical prediction approaches in determining the extent of distortion are limited by the availability of extensive test data and the absence of specific identification of driving factor/s for distortion. To address the issue, this study proposes an innovative method to develop the hypothesis for identifying the critical contributing factors for distortion and a novel finite element based framework is developed for validating the hypothesis. The framework is implemented on a experimental non-prismatic industrial part and the results support the proposition that quenching is the most significant contributor to distortion in thin-walled parts made from Haynes 282 alloy. The framework/model provides valuable insights into the significant contributions of quenching induced thermal gradients and the material state towards part distortion. It is adaptable for predicting distortion in thin-walled geometries made of Haynes 282, overcoming the limitations of current numerical prediction methods. [ABSTRACT FROM AUTHOR]

In this paper, we study the quenching phenomenon related to the ω-diffusion equation on graphs with a potential and a singular source ut(x, t) = Δωu(x, t) + b(x)(1 - u(x, t))-p, where Δω is called the discrete weighted Laplacian operator. Under some appropriate hypotheses, we prove the existence and uniqueness of the local solution via Banach fixed point theorem. We also show that the solution of the problem quenches in a finite time and that the time-derivative blows up at the quenching time. Moreover, we estimate the quenching time and the quenching rate. Finally, we verify our results through some numerical examples. [ABSTRACT FROM AUTHOR]

To achieve the necessary mechanical properties and high corrosion resistance, heat treatment is based on a significant alteration in the microstructure of metals and alloys. The metal is heated above a critical temperature during heat treatment processes. Several methods, such as quenching and cooling in various media, followed by tempering and other heat treatment operations, can be used to achieve this. Steel can be made more malleable by annealing, which also increases ductility and improves corrosion resistance. In this study, thirty medium carbon steel specimens were used, which were split into different groups, various heat treatments were applied. First quenching, first tempering, second quenching, and second tempering were among the heat treatment procedures used, and cooling media made of distilled water were used at various temperatures. After that, the corrosion rate in these specimens was looked at, and the results were compared to the corrosion rate in the base specimen. The results show that repeated heat treatment of the metal generally lowers the rate of corrosion in the metal, particularly when distilled water is used for the cooling process after the two tempering stages at a temperature of almost absolute zero. The findings show that the second sample had the lowest corrosion rate of all the samples. When compared to the corrosion rate in the basic sample, the corrosion rate in this sample decreased by about 92.9%. [ABSTRACT FROM AUTHOR]

The existence of warfarin is beneficial for health, but its increase in the human body causes toxicity and increases the risk of bleeding. This research focuses on introducing a facile and safe fluorescence sensor for warfarin detection in biological samples. The synthesis of the fluorescence sensor probe was easily performed with doping metal ions of the Pt to CdTe quantum dots. The morphological and optical properties of the synthesized Pt:CdTe quantum dots were characterized by FT-IR, TEM, and EDX. The interaction patterns of warfarin with CdTe QDs were investigated by the quantum chemical method and compared with experimental results. The proposed quantum dots exhibited a blue luminescence with a 28.8% quantum yield. Pt:CdTe QDs were used as the fluorescence probe to assay warfarin. This procedure is based on the "off" fluorescence of quantum dots in the presence of different concentrations of warfarin. Under optimal conditions, the fluorescence sensor probe could detect the concentration of warfarin with a wide linear range of 0.1–100 μM and a detection limit (S/N = 3) of 0.05 µM. Results of sample analysis by fluorescent nanoprobe displayed that this probe could be the potential alternative tool for warfarin detection in biological samples. [ABSTRACT FROM AUTHOR]

The influence of additives on the decomposition and combustion characteristics of electrically controlled solid propellants was investigated through small scale experiments. Carbon black and aluminum additives were explored in a polyethylene oxide, lithium perchlorate propellant. Additives were used to improve the voltage response and their impact on ignition and combustion was characterized. The data showed that conductive additives can mitigate the loss of solid phase conductivity through solvent evaporation and that ignition delay decreases with higher voltage and solid phase conductivity. Steady‐state combustion experiments showed that electrical decomposition of the propellants proceeded more rapidly than a purely thermal stimulus illustrating the importance of electrochemistry in ECSP combustion. The combined effects of pressure and voltage on combustion rates were summarized in Saint‐Robert's burn relations. The regression rates increased with both applied voltage and pressure. The pressure deflagration limit of propellants with the carbon black additive was significantly reduced compared to a neat PEO/LP propellant, whereas the addition of 10 % aluminum did not affect the pressure deflagration limit. [ABSTRACT FROM AUTHOR]

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

A novel flameless operating mode is introduced, which improves the response of a multiple flame photometric detector (mFPD). The mFPD normally has analyte travel through 4 'worker' flames in series before entering a final 'analytical' flame where its emission is monitored. Here, it is found that when the analytical flame is not ignited, background luminescence is reduced over 30 times and the strong analyte chemiluminescence of the worker flames can be made to extend a large distance (~ 10 flame widths) into the analytical flame region where it is detected. This occurs for phosphorous (HPO*), quadratic sulfur (S2*), and linear sulfur (HSO*) emission. Conversely, carbon emission resides inside the worker flames and yields a small negative signal. As a result, very good selectivity over carbon is observed, and improved minimum detectable limits (MDL) of 4 pg S/s (S2*) and 0.3 pg P/s (HPO*) are obtained, which are up to 20 times lower than previous values reported for the mFPD. Further, linear sulfur (HSO*) yields an MDL of 6 pg S/s, which is over 3 times lower than values reported for other FPDs. Due to the worker flames present in this mode, other benefits of regular mFPD operation are maintained, like uniform analyte response and large quenching resistance. In application, a trace benzothiophene analyte is readily detected within a concentrated diesel fuel matrix in the flameless mFPD mode, while no response is observed in the conventional FPD mode. Results indicate that this flameless operating mode is advantageous for sulfur and phosphorous analysis. [ABSTRACT FROM AUTHOR]

The evolution of carbides and the hardness of GCr15 bearing steel specimens during the quenching process were investigated using scanning electron microscopy (SEM) and hardness testing. The volume fraction and size of undissolved carbides under different quenching parameters were analyzed. The results indicated that as the austenitizing time increased from 0 to 25 minutes, the volume fraction of undissolved carbides decreased from 10.77 to 5.72 %, while the mean diameter of undissolved carbides first decreased from 0.264 to 0.214 μm, and then increased to 0.227 μm; as the austenitizing temperature increased from 810 to 930 ℃, the volume fraction decreased from 9.25 % to 0.53 %, while the mean diameter first decreased from 0.238 to 0.222 μm, and then increased to 0.248 μm; as the heating rate increased from 2 to 8 ℃/min, the volume fraction increased from 5.10 to 6.76 %, while the mean diameter decreased from 0.234 to 0.217 μm. It is found that the energy absorbed during austenitization plays a crucial role in the volume fraction and mean diameter of undissolved carbides. That is, before the heat treatment reaches equilibrium or the carbides are fully dissolved, as the energy absorbed during the heat treatment process increases, the volume fraction of undissolved carbides decreases, while the mean diameter of undissolved carbides tends to increase. It is demonstrated that the hardness of the GCr15 bearing steel specimens is closely related to the volume fraction and mean diameter of undissolved carbides. That is, before the coarsening of carbides, the hardness of GCr15 steel specimens gradually increases as the volume fraction of carbides decreases.

AISI 1045, Medium-carbon steel is commonly used as machining components like bulldozer bushings and widely used in construction equipment such as hammerheads. Hence, it needs good hardness and impact resistance. The methods to achieve these properties are through a heat treatment process called quenching and tempering. This research analyzed the effects of various austenitizing holding times during the quenching and tempering process on the microstructure, hardness, and impact strength of AISI 1045 steel. The procedure involved quenching the steel at a temperature of 850°C with austenitizing holding times of 5, 15, and 25 minutes, followed by rapid cooling using ice water. Subsequently, tempering was performed at 500°C with a holding time of 15 minutes, followed by air cooling. The research showed that all three test specimens exhibited bainite and martensite phases. The hardness of the steel increased after undergoing the quenching and tempering process, with the highest hardness value obtained at a 5-minute austenitizing holding time, measuring 32.37 HRC. Additionally, there was an increase in impact strength after the quenching and tempering process. Tobe found the highest impact strength value observed at with a 25-minute austenitizing holding time at 27.39 J/cm².

In this paper, we addressed a coupled electromagnetic and thermal field problem in an induction heating process. The paper presents the results obtained through numerical simulation of the electromagnetic field coupled with the thermal field in electromagnetic induction heating systems. The modeling results largely depend on the accuracy of the material properties data and their variation with temperature.

In a corrosive environment, it is crucial to increase the hardness and corrosion resistance of mild steel bucket excavators. Making a hard layer of nickel-chromium (NiCr) alloy by the deposition method is one of the many approaches to achieve this. In this research, a hard layer was deposited on the upper surface of mild steel using manual metal arc welding (MMAW). Starting with the addition of NiCr alloy during welding, the process continued with a quenching technique using different cooling media. In order to examine elemental composition, crystal structure, and microstructure, Optical Emission Spectroscopy (OES), X-ray diffraction (XRD), and optical microscopy (OM) are employed. The evaluation of hardness values, material deterioration, and electrochemical behaviour of the deposited layer involves hardness tests, digital balances, and potentiostats. Due to its improved hardness and corrosion resistance, NiCr has been successfully added to deposition layers. The increase was attributed to the presence of martensite and ferrite phases generated by the quenching technique and NiCr on the surface layer. The hardness value and corrosion resistance of samples coated with NiCr after being rapidly cooled in an oil medium are found to be suitable for excavator buckets, according to experimental findings.