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Oxygen-assisted high temperature solid-state reaction approach was employed for the fabrication of Pr activated Ba(Mg0.28Zr0.16Ta0.56)O3 transparent ceramic phosphor. Retiveld refinement of X-ray diffraction pattern was carried out to reveal the lattice parameters and crystal structural information. Under the blue-light excitation of λex=473 nm, the phosphor exhibits a sharp intense red emission centered at 645 nm, accompanied by serval other weak peaks. PL evolution with temperature shows a significant luminescence quenching behavior, and the underlying multi-phonon interaction with optical center is revealed by proposing an unprecedent theoretical calculation work. Such a phonon effect is further confirmed from the red-shift of peak position with temperature, and the involved phonon energy of 50.7 meV is determined from Raman scattering measurement. More interestingly, the fitted results of transient-state PL spectra show a fluctuation of luminescence lifetime at various temperatures, further indicating a significant effect of phonon vibration in the system.

An optimal switching heating control strategy based on minimum margin (OS-MM) is proposed for high efficiency, low energy consumption, and high-uniformity fine control in a large-scale vertical quench furnace. This work was stimulated by the need for solving the contradiction between the heating rate and temperature overshoot to achieve a rapid rise in temperature with no overshoot. Based on a three-dimensional (3-D) transient temperature field model of the quenching furnace, the temperature field optimization control problem is transformed into a boundary optimization control problem of rapid heating, whereby it is rigorously proved that the fastest rise in temperature is attained by the full-power heating, which satisfies the bang-bang characteristics. The key parameter that determines the overshoot in the full-power heating mode is introduced and defined as the minimum margin in the temperature-rising process. The analytical expression for solving the minimum margin is calculated by the eigenfunction expansion method and using the strong metal thermal inertia of the internal temperature field, the OS-MM method is designed to stop the heating in advance at a calculated switching point to optimize full-power heating, thus conserving energy by reducing its consumption. The results of simulation and industrial experiments show that this strategy greatly shortens the temperature adjusting time, significantly reduces energy consumption, and effectively improves the control performance indices, such as overshoot and static error in the temperature holding period of the thermal treatment process, as compared to the existing heating methods.

The aim of this research was to evaluate the production of glass ceramics from novel combinations of fly ash, glass cullet, blast furnace slag and copper slag solid wastes. The CaO/SiO2 molar ratios of the mixtures were 0.17–0.39. Glass ceramics were produced by thermal treatment of frits obtained by quenching in water. The results show that samples with a high Fe2O3 content (>4 wt%) are not adequate for glass-ceramic formation, as a result of the effect of ferric iron, Fe3+, which increases the network connectivity, on the stability of the glass. The mechanical properties of the ceramic materials were as follows: elastic modulus of 97.8–106 GPa, Vickers microhardness of 612–701 MPa, fracture toughness of 0.45–0.84 MPa m1/2, and friction coefficient of 0.57–1.0. For the glass ceramics, the mass loss did not exceed 1% in NaOH and 15% in HNO3 as a result of the crystalline phases formed. The ceramic materials developed in this research could be considered for potential applications in the production of glazes for residential or industrial tiles and coatings, among others.

In this study, the crystallization behavior of Al86Ni8Y6 upon rapid cooling from the equilibrium melt is investigated and the crystalline phases that compete with the glass formation are identified. Al86Ni8Y6 is one of the best glass formers in the ternary Al-Ni-Y system. Contrary to previous studies suggesting α-Al as the primary phase upon quenching, this study reveals that glass formation is strongly restricted by the formation of the primary precipitating ternary intermetallic compound Al23Ni6Y4. The nucleation of Al23Ni6Y4 appears to be triggered by yttrium oxide particles present in the melt acting as heterogeneous nucleation sites. Once the primary phase Al23Ni6Y4 has been formed, further crystallization of the Ni and Y depleted melt occurs as α-Al. The corresponding results are shown and discussed with respect to their effects on the glass formation.

The metastable α' phase and dislocation characteristics (e.g., density and constituents) are of vital importance for the mechanical responses of (α+β) titanium alloys. In this work, to reveal the in-depth decomposition mechanisms of dislocations and metastable α' and their influences on mechanical properties in a Ti-6Al-4V (α+β) alloy, the thermal stability of different microstructures tailored by various cooling approaches were investigated utilizing scanning electron microscope, electron backscattered diffraction, transmission electron microscope and X-ray diffraction line profile analysis. The results showed that the initial characteristics of α' and α laths and dislocation density were influenced by the cooling methods remarkably. The thermal stability of Ti-6Al-4V alloy increased with decreasing cooling rate. The improvement in thermal stability can be ascribed by the decrement in dislocations, partitioning of the alloying elements and grain orientations variation of the α' lath and α phase. It is also found that the plastic strain accommodation of β→α' transformation was dominated by dislocations. During stabilization annealing treatments, the , and dislocations simultaneously decomposed. The decomposition of dislocations and metastable α' phase during various stabilization annealing and the particular twins and stacking faults microstructures formed during quenching have a great influence on the properties of the studied Ti-6Al-4V alloy.

In this study, a La0.8Ba0.2TiO3−δ (LBT) upper layer was deposited on an yttria-stabilized zirconia (YSZ) thermal barrier coating (TBC) through atmospheric plasma spraying. The thermal cycling behaviors of the YSZ single-ceramic-layer and LBT–YSZ double-ceramic-layer coatings at 1000 °C were investigated through a water quenching method. Moreover, phases, microstructural evolution, and elemental distributions were studied through by X-ray diffraction and scanning electron microscopy–energy-dispersive X-ray spectroscopy. The results showed that the thermal cycling lifetime of the LBT–YSZ coating was 27% higher than that of conventional YSZ coating. The conventional YSZ coating failed after 251 cycles because of the joining of the continuous horizontal and vertical cracks caused by the formation of thermal growth oxides and the bending effect of the single-ceramic-layer structure. The thermal cycling behavior of the LBT–YSZ coating was different from that of the YSZ coating at the edge and center. Although the former was similar to the failure behavior of the YSZ coating, the cracks in the vertical direction were deflected as a result of the bending effect of the double-ceramic-layer structure during quenching. This deflection led to the formation of slope cracks with longer propagation paths and slope spallation zones. The latter showed small-debris spallation on top of the LBT upper layer due to the lower fracture toughness of the LBT, which protected the central coating from the structural damage of the ceramic coating. These two behaviors would either release the thermal stress or increase the crack-propagation energy requirement in the ceramic coating, consequently improving the thermal cycling lifetime of the LBT–YSZ coating. In summary, depositing an LBT upper layer could potentially improve the thermal cycling lifetimes of TBCs.

We have developed photon counting detectors based on InGaAs/InP SPAD for space object laser ranging. Two key versions of detector control electronics were developed, tested, and compared: passive quenching and active quenching. The key parameters of these two photon-counting detector versions were determined. The photon detection probability exceeds 20% for both versions. The timing jitter as low as 28 ps RMS was achieved for passive quenching version. The detection delay stability on the level of a fraction of picosecond was achieved for the active quenching version. The effective dark count rate as low as 160 kHz was achieved. The passive quenching electronics version was optimized for applications in which the high timing resolution is preferred. The active quenching electronics was optimized for applications, where sub-picosecond long term detection delay stability is needed.

Ultrahigh-strength quenching and partitioning (Q&P) steels have attracted strong interests in the auto manufactory, while the comprehensive understanding in the microstructure and mechanical behavior of their welded joints is highly needed to enrich their applications. In the present work, it is designed to make an insight into these imperative conundrums. Equal strength Q&P 1180 steel joints to parent metal were successfully fabricated via friction stir welding (FSW) technique under different parameters. Apparent hardening and softening were observed in stir zone (SZ) and heat-affected zone (HAZ) respectively, whose microstructures strongly depended on the peak temperature and cooling rate during welding. The formation of fresh martensite was the main mechanism for the SZ hardening, while the decomposition of metastable phases played key roles in the microhardness drop of the HAZ. A heat source zone-isothermal phase transition layer model was proposed to clarify the impregnability of the joint strength under parameter variation. The dual-phase structure, nano-carbide particles, tempered initial martensite, and ultrafine-grained ferrite synergistically improved the strain hardening ability of the HAZ, which eventually resulted in the equal strength FSW joints.

To investigate the effect of surface-modified nanoparticles (NPs) on the inclusion refinement and microstructure evolution, deoxidized experiment ingots with different amounts of modified NPs were manufactured under different cooling conditions. Laser scanning confocal microscope (LSCM) was hereby used for in-situ observation of the phase transition and microstructural evolution during heat cycle process. The results revealed that the inclusion size was always smaller under water quenching than under air cooling, and the number of inclusions was greater under water quenching. After NP addition, the nucleant inclusions were identified as MgAl2O4 spinel and irregular TiN inclusion from SEM-EDS measurement and equilibrium calculations using Factsage thermodynamic software. The higher cooling rate under water quenching resulted in less polygonal ferrite decrease and the formation of bainite in the steel. The LSCM experiments showed that ferrite side plates (FSP) always formed on the boundary prior to the formation of acicular ferrite (AF) on the intragranular inclusions, and the start transformation temperatures of FSP and AF phases both lowered after NP addition. The higher cooling rate and NP addition contributed to AF formation and increased the degree of interlocking of the AF phase. Finally, the relationship between the characteristics of inclusions and the kinetics of AF was investigated.

High strength and thermal shock resistant mullite-bonded porous SiC ceramics are essential for applications in catalyst, hot gas/solid filtration/separation fields. However, these properties were limited by the contradictory issue: higher temperature is necessary for the formation and densification of mullite bond phase, while lower temperature is preferred to avoid sever oxidation of SiC accompanied with detrimental cristobalite phase. Herein, a novel composite additive system, Al(OH)3+Y2O3+CaF2, was proposed to solve this problem for one shot. Flexural strength as high as 113 MPa (40.3 vol% porosity) was achieved for samples sintered in air, even higher than that fabricated by expensive SPS technique (103 MPa, 35.7 vol%). Critical quenching temperature reached 547 °C, around 227 °C improved. Meanwhile, additives acted as pore formers and small variation of them could effectively modify the size and shape of pores. The evolution of pore structure with additives was thoroughly evaluated and models were established for the first time. Correlations of phase composition, microstructure, porosity, pore size and shape to the performance of porous SiC were investigated. This work provides a flexible strategy to simultaneously control the mechanical performance and pore structure for low cost porous SiC ceramics.

A correlation between piezoelectricity and photoluminescence is investigated for europium doped (Na0.41K0.09Bi0.5)TiO3 ceramic. An optimum piezoelectric and dielectric response is observed for 1.0 at.% Eu doped (Na0.41K0.09Bi0.5)TiO3. For doping concentration higher than 1.0 at.% a gradual fall in the piezoelectric response is observed which is associated to the amphoteric nature of Eu3+ ion. On the contrary, the photoluminescence intensity increases monotonically with the increase in Eu concentration. On application of an electric field, although there is no noticeable shift in the position and shape of the photoluminescence line, a quenching of hypersensitive 5D0 → 7F2 transition is observed. The quenching effect is more evident for lower doping concentration (less than 2.0 at.%) of europium. The emergence of irreversible tetragonal phase, after application of the electric field, is attributed to the quenching of 5D0 → 7F2 transition. Based on these investigations it is concluded that the piezoelectric and photo-luminescence lack one-to-one correlation. The PL response is associated to the local site symmetry around Eu3+ and it is independent of the development of long-range ordering.

All available thermodynamic data and phase diagram data in the Al2O3–ZrO2, CaO–Al2O3–ZrO2, and Al2O3–SiO2–ZrO2 systems at 1 bar total pressure were critically evaluated and assessed simultaneously to obtain a set of the optimized Gibbs energies of all phases in the systems. Due to the lack of reliable data on the mutual solubility of Al2O3 and ZrO2, key phase diagram experiments in the Al2O3–ZrO2 binary system were carried out by using a classical phase equilibrium and quenching technique followed by the EPMA phase analysis. Based on the optimized Gibbs energies, the reliable experimental phase diagram and thermodynamic property data of the Al2O3–ZrO2, CaO–Al2O3–ZrO2, and Al2O3–SiO2–ZrO2 systems are well reproduced, and unknown phase diagram and thermodynamic properties are predicted.

Al–SiC and hybrid Al–SiC-graphite MMCs with up to 70 vol% SiC and 10 vol% graphite were fabricated using spark plasma sintering. Detailed studies of the microstructure, Vickers hardness, longitudinal elastic constant C11, as well as thermal shock resistance of the MMC samples were carried out. Non-destructive ultrasound phase spectroscopy was used to measure the C11 elastic constant of the MMCs, and the measured values were compared with different micromechanical models for particle reinforced composites. For both two- and three-component MMCs, the Hashin Shtrikman lower bound fitted best to the experimental results in the absence of any porosity. Thermal shock resistance of the MMCs was carried out by heating in air to 500 °C and subsequently quenching in water for ten times. The extent of thermal shock-induced structural alteration was determined via a systematic study of the change in density, hardness, and C11 of the samples. It is observed that the thermal shock resistance of the MMCs depends upon multiple factors such as SiC content, graphite content, and the amount of residual porosity. While the reduction in mechanical properties of the Al–SiC MMCs due to graphite addition is according to the expected line, the present study shows that graphite addition also reduces the thermal shock resistance of the MMC.

In this study, we employed a luminescenct agent CsPbCl3 perovskite nanocrystal for Cu2+ detection, and achieved a prominent enhancement in sensitivity by the introduction of ytterbium acetate (Yb(OAc)3). The introduced Yb(OAc)3 is capable of causing a morphology transformation of CsPbCl3 nanocrystals from initial nanocubes into one-dimensional (1D) nanowires (NWs). The formed 1D CsPbCl3 NWs paved a direct charge transport path and exhibited low defect density as well as superior conductivity, which were beneficial to accelerating the rapid electron transport from the luminescent agent to Cu2+, and to give rise to an efficient inhibition of undesired charge trap, respectively. Besides, AcO− rendered a reduced steric hindrance during the formation of a copper-based counter-ion pair, thus improving the adsorption capacity of Cu2+ on the surface of the luminescent agent, CsPbCl3 nanocrystals. As results, the 1D Yb(OAc)3 passivated CsPbCl3 NWs exhibited efficient luminescence quenching for enhanced detection sensitivity. This Yb(OAc)3-involved system exhibited a detection limit as low as 0.06 nM in the Cu2+ detection window range from 0 to 1000 nM, and such value is optimal in the documented works for Cu2+ detection based on luminescent perovskite materials.

Silicon is an essential alloying element in quenching and partitioning (Q&P) steels, because it is known to suppress carbide precipitation during partitioning step and promote carbon partitioning to stabilize austenite. When 2 wt% Si was added to 10Mn-2Al-0.2C steel, the size and fraction of the carbides formed during partitioning became smaller than in the Si-free counterpart. Moreover, the suppression of carbide formation promoted C partitioning into austenite as expected. However, austenite stability was always lower with Si under the equivalent partitioning condition because Si effectively decreased the stacking fault energy of austenite. As partitioning progressed, the both yield and tensile strengths of the Si-added steel exceeded that of the Si-free steel with the similar ductility level. This was because Si was an effective solid solution strengthener, and the austenite in the Si-added steel exhibited the appropriate stability to gradually transform into martensite throughout the deformation. The resulting strengthening effect compensated for the softening caused by martensite recovery. Consequently, strain hardening rate decreased continuously throughout deformation, which resulted in high tensile strength and ductility.

The self-ignition of hydrogen/air is an important process in the micro thermophotovoltaic system. The transient numerical models of gas-phase reaction and catalytic reaction in the various catalytic micro combustors were built and verified. The self-ignition process of gas-phase reaction caused by catalytic reaction in the catalytic micro channel with conventional heat dissipation was studied. The self-ignition process could be divided into four stages, fuel diffusion stage - pure catalytic reaction stage - flame front moving stage - stable combustion stage. The ignition time and temperature limit at different inlet temperatures, inlet velocities and channel heights were analyzed. The results showed that the wall quenching effect, thermal effect and flame propagation effect are dominant at low temperature, medium temperature and high temperature respectively. The catalyst length and the mixture internal energy were the main factor at low inlet velocity and high inlet velocity respectively. The steady-state time was also studied in the various operation conditions. Finally, the catalytic combustion characteristics in the stable combustion stage were analyzed. The influence of inert section length, inlet temperature and inlet velocity on the maximum temperature and fuel conversion ratio were investigated.

In this study, 0.12Cr, 0.12Ni and 0.06Mo were added to the ordinary Si-Mn steel to investigate the effect of chemistry on the microstructure and mechanical properties of the Si-Mn steel. Various combinations were done but these produced optimal results. The steels were hardened and soaked at different temperatures with reports coming from only heat treatment of austenitising at 870 °C for 1800 s and tempering at 560 °C for 7200 s. The samples were quenched in oil that was maintained at 30 °C. The light optical microscope (Olympus BX51M) with the aid of the Olympus Stream Essentials software and the scanning electron microscope (Jeol JSM-IT300LV SEM) were used for the microstructural analysis. The Vickers hardness tester and Instron tensile testing machine were used to evaluate the mechanical properties. The room temperature tensile tests were carried out at a strain rate of 10−3/sec. The microstructure obtained after quenching and tempering was largely tempered martensite. The results also showed that the hardness slightly increased after adding the above alloying elements i.e. 373 Hv and 360 Hv for the modified and unmodified steel respectively. The yield strength of the modified steel was found to be 1020 MPa while that of the unmodified was found to be 960 MPa which corresponded with the hardness values. On the contrary, the Charpy impact energy of the steels remained unchanged with unmodified and modified steels recording average energies of 28 and 27 J respectively. In other words, the modified steel showed improved mechanical properties as compared to the unmodified steel when subjected to the same quench and temper conditions.

Heat treatment, in conjunction with quenching, is used to improve the mechanical characteristics of oil hardened steel. In order to get the greatest yield strength, hardness, and ultimate tensile strength, among other things, a variety of control parameters must be tweaked in order to achieve the optimum outcomes. One of the objectives of this study is to improve the process of improving the mechanical properties of AISI 4140 Chromoly steel by varying key parameters such as the quenchant used, the soaking time, and the heat treatment temperature. After using the Taguchi method for the purpose of experimental design, three output responses were produced, namely the yield strength, the hardness, and the ultimate tensile strength of the material. To determine the most optimum parameters for heat treatment and quenching, the Weighted Aggregated Sum Product Assessment method (WASPAS) was used. In this study, it was discovered that the hardness of the material is dependent on the heating temperature, with greater hardness being obtained at the highest possible heating temperature. A similar relationship exists between material strength and soaking time, with the greatest amount of soaking time leading to greater material strength. When comparing the mechanical properties of the three quenchants, new engine oil performed much better than coconut oil and old engine oil. It is clear that both the WASPAS method and the Taguchi-WASPAS method approach are very effective, as shown by the close agreement between the anticipated and experimental results. The ANOVA results revealed that among all of the factors considered for maximisation of mechanical characteristics in heat treated and quenched Chromoly steel specimens, temperature was the most significant and influencing factor, followed by soaking time as the second most significant parameter, and quenchant as the least significant variable. The relevance and effectiveness of both optimization approaches were also shown by a confirmatory test, which was conducted.

The glass compositions (20-x)K2O-xBaO–30TiO2–50P2O5 with (0 ≤ x ≤ 20 mol%) were elaborated using the conventional quenching method. Their related glass-ceramics were developed by controlled crystallization under heat treatments. UV–visible absorption was employed to study the optical properties of the glasses. This technique showed the reduction of Ti4+ to Ti3+ ion content with the substitution of K2O by BaO, and it was found that the BaO addition reduces the structural disorder in the studied glasses. The electrical properties of the glass-ceramics were carried out by impedance spectroscopy in the frequency range from 10 Hz to 1 MHz under various temperatures from room temperature to 550 K. The obtained results showed that the electrical conductivity follows Jonscher’s universal power law and the electrical motion process in the glass-ceramics is provided by the hopping mechanism.

Ti3AlC2/2024Al composites with a co-continuous structure were successfully fabricated from 2024Al powders and Ti3AlC2 porous preforms (with porosity of 48%, 41% and 35%, respectively) by pressureless infiltration at 930 °C. Long-rod like Al3Ti was in situ formed due to reaction of Ti atoms de-intercalated from Ti3AlC2 and liquid 2024Al, which interpenetrated with Ti3AlC2 to form a new continuous framework. The mechanical properties in relationship with the initially different volume fractions of Ti3AlC2 and 2024Al at room temperature and high temperature were investigated. At room temperature, 59 vol%Ti3AlC2/2024Al has the best comprehensive mechanical properties, with the flexural strength of 510 MPa, compressive strength of 729 MPa, and compressive strain of 5.49%. Due to the co-continuous structure and the excellent high temperature of Al3Ti, all samples exhibit well mechanical properties at 300 °C. Among them, 52 vol%Ti3AlC2/2024Al has the best performance with the ultimate compressive strength of 532 MPa, which is only 18.7% lower than room temperature. And even at 400 °C,it still has an objective compression strength of 394 MPa due to the highest content of Al3Ti. In addition, after quenching from 400 °C to room temperature, the residual flexural strength of 52 vol%Ti3AlC2/2024Al can be reached to 450 MPa with the mere reduction rate of 7.4%. And no cracks are observed at the boundary of each phase, which means the good thermal shock resistance of the composites.

In this paper, the effects of non-isothermal oxidation on transient conjugate heat transfer of the cryo-supersonic air-quenching are investigated based on a double-layered oxidation kinetics model, while a unified conjugate heat transfer formula is developed to synthetically consider the near-wall turbulence, non-isothermal oxidation, and surface radiation. The comparison between numerical and experimental results are also presented to check the validity of the developed model. The results indicate that the film growth has some degree of inhibition to the conjugate heat transfer, in particular, the stagnation temperature increases linearly by about 5 K per 100 μm increase in film thickness, and the effective conjugate heat transfer coefficient in the stagnation region decreases linearly by about 55 Wm-2K-1 per 100 μm increase in film thickness. Moreover, the oxide film would have little impact on transient conjugate heat transfer when the near-wall velocity is higher due to the effect of viscous dissipation.

Partially premixed combustion is one of the developing areas of combustion research that has the advantages of both premixed and diffusion mode of combustion. The present work involves a computational study on the stability and characteristics of partially premixed butane-air flames. The effect of operating parameters like fuel-air ratio, primary aeration, and the presence of co-flow and co-swirl on the stability and flame characteristics has been studied. The simulation results show that the height of the flame decreases with an increase in primary aeration and also in the presence of a co-swirl stream. It has also been found that the stability of flames increases with co-swirl air but deteriorates with the presence of the co-flow air. The flame temperature increases with primary aeration and it has been observed that the peak flame temperature shifts away from the burner mouth for lower primary aeration. It has been observed that the flame stability improves with co-swirl air which is attributed to the recirculation zone created due to the swirl motion which acts as a heat source. The poor stability in the presence of co-flow air is attributed to flame stretching and aerodynamic quenching of the stretched flame lets. The lift off velocity and the stable operating range increases with equivalence ratio and also with co-swirl air.

In this paper, Ba0.75Al11O17.25 was selected as the host for the Eu2+ and Mn2+ co-dopants due to the Reidinger defects in its lattice. Upon the 365 nm excitation, the phosphors presented the cyan to green tunable emission by changing the doping concentration of Mn2+. Moreover, this phosphor possesses zero-thermal quenching up to 448 K due to the interaction between the traps and Eu2+/Mn2+. The completely densified ceramic guaranteed the high optical transmittance (∼72 % at 516 nm) and thermal conductivity (4.3 W·m−1·K−1 at room temperature). When combined with a 6 W commercial 365 nm emitting LED chip, the temperature of the ceramic eventually stabilized at 428 K and the luminous efficacy of the LED device was almost not influenced by the thermal quenching effect. This work may open a way for exploring new phosphor conversion materials for HP/HB PC solid state lighting.

Duplex stainless steel (DSS) with an austenite-ferrite duplex microstructure offers high strength and toughness, excellent resistance to intergranular and chloride corrosion, and good weldability. The strain hardening behavior of austenite and ferrite phases in duplex stainless steel, when subjected to a tensile stress condition, is studied in the current work. Specimens were prepared from test blocks soaked at a temperature of 1160˚ C followed by furnace cooling to 1060 ˚C and water quenching. Heat-treated samples were deformed for varied percentage elongations. Microstructural analysis using optical microscopy revealed the deformations in austenite and ferrite phases. The concentrations of component alloying elements were determined using Energy Dispersive X-Ray Analysis (EDX) and area-scan techniques. At each level of percentage deformations, as well as on the fractured sample, microhardness measurements were taken on both austenite and ferrite phases. The hardness values of both austenite and ferrite phases were observed to rise continuously with an increase in deformation. The rise in hardness value of the ferrite phase was found to be significantly higher than the rise of hardness in the austenite phase, proving that the ferrite phase has a higher work hardening with deformation.

Typical high-entropy fluorite oxides with five metal cations have exhibited improved thermomechanical properties. In this work, we have successfully prepared single-phase high-entropy (Zr0.2Ce0.2Hf0.2Y0.2Al0.2)O2-δ fluorite oxides through the combination of sol-gel method and calcination, using metal nitrate/chloride, citric acid and absolute ethanol as the primary raw materials. A series of characterizations were employed for chemical, morphological and structural analysis of the calcined products. The five cationic elements were shown to be uniformly distributed in the nearly pure fluorite oxide without apparent segregation at the micro/nano-meter scales after 1500 °C calcination. Annealing and water quenching within the test temperature range did not witness any appreciable phase transition. It is revealed that the concentration of Ce3+ in Ce ions reaches 33.84% and δ is equal to 0.234, yielding a nominal composition of (Zr0.2Ce0.2Hf0.2Y0.2Al0.2)O1.766. Cation and anion configurational entropy were found to be 1.609 R and 0.722 R, respectively, where R is the ideal gas constant, for a sum of the total configurational entropy of 2.331 R in the high-entropy system. Line defects inside the crystals and 3 types of crystalline boundary structures have been observed and identified among the mostly atomically sharp grain boundaries.

The present work consists in performing a quenching and tempering heat treatment to AISI 4340 steel at different temperatures in order to determine the torsional resistance and hardness, and thus, to make a comparison between the supply material and the heat-treated material to verify if its chemical and mechanical properties are improved. From the above, the results show that there is an in-crease in hardness between the different heat-treated specimens. In addition, an increase in its mechanical properties such as torsional resistance is provided, and it is concluded that performing a heat treatment has great benefits depending on how the AISI 4340 steel is going to be used.

At present, the combination of red, green and blue light (RGB) is one of the mainstream ways to obtain high-efficiency white light emitting diodes (w-LEDs). In this paper, we have prepared a new type of Sm3+ activated Ca2LaSbO6 (CLSO) orange-red phosphor by the high-temperature solid-phase method. The phase and morphology of the powders were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. The luminescent properties, thermal stability of the materials have been tested and analyzed in detail. The results show that CLSO:Sm3+ phosphors have several excitation bands in the range of 320–550 nm, and the excitation peak intensity at 405 nm is the largest, indicating that the material can be excited by blue light. The emission peak is composed of 564 nm (yellow), 601 nm (orange) and 648 nm (red), emission intensity reaches the extreme value when the Sm3+ doping concentration is 5 mol%, the quenching phenomenon is due to the dipole-dipole (d-d) interaction of Sm3+ ions. The activation energy (Ea) of Sm3+ in CLSO is 0.2689 eV. The CIE chromaticity coordinates of CLSO:Sm3+ located at origin-red region. All results show that CLSO:Sm3+ phosphor has potential application value in w-LEDs field.

Ag3PO4-based photocatalysts have been deeply studied in environmental remediation; however, two problems limited their further application: photocorrosion and quenching effect by in-situ generated H2O2. To addressed these two questions simultaneously, Fe2(MoO4)3 was coupled with Ag3PO4 to construct Z-scheme Fe2(MoO4)3/Ag/Ag3PO4 heterojunction driven by internal-electric-field. The rhodamine B degradation rate of heterojunction was 254 and 7.0 times higher than those of Fe2(MoO4)3 and Ag3PO4, respectively. The outstanding photoactivity was due to the high visible-light harvest, low interface resistance, high separation efficiency of charge carriers, long lifetime of hole (h+) and electron (e-), well-preserved oxidation potential of h+, and especially photocatalytic produced H2O2 inside the system. The in-situ generated H2O2 was fully activated to be •OH on the Fe2(MoO4)3 surface via a Fenton reaction, leading to the elimination of quenching effect on h+ and e-, and generation of more •OH. Additionally, in Z-scheme heterojunction, e- transferred from Ag3PO4 to Fe2(MoO4)3, avoiding the accumulation on Ag3PO4 surface, and hence suppressing the photocorrosion. As a result, 91.2% of degradation efficiency remained after 5 cycles. This paper provides a new method to simultaneously increase the degradation rate by utilizing the in-situ generated H2O2 and improve the stability of Ag3PO4 via constructing a Z-scheme heterojunction.

A compact high-speed active quench and reset (AQR) circuit integrated with a p+/n-well single-photon avalanche diode (SPAD) is designed and fabricated in a standard 65 nm CMOS technology. The post-layout simulations showed that the quenching time for this AQR circuit is only 0.1 ns, and the smallest dead time is 3.35 ns which corresponds a maximum count rate of ~300 Mcps. The measurements showed that the SPAD pixel achieved a dark count rate of 21 kHz, a peak photon detection probability of 23.8% at a 420 nm wavelength and a timing jitter of 139 ps (using a 405 nm pulsed laser) when the excess voltage was 0.5 V. Also, due to the short quenching time, negligible afterpulsing was observed during the measurements.

The effects of the Zn/Mg ratio on the precipitate behavior and mechanical properties of Al-Zn-Mg-Cu alloys at different quenching rates were investigated by a Jominy end-quench test, tensile test and microstructural analysis. The results show that the hardness and strength of the aged alloys clearly decrease with increasing quenching distance (D). Additionally, the alloy with a Zn/Mg ratio of 5.42 has a more obvious drop in yield strength than the alloy with a higher ratio of 7.09 when D is varied from 10 mm to 142 mm. During slow quenching, fewer equilibrium η phases are formed in the alloy with a higher Zn/Mg ratio of 7.09, and then a larger number of fine η′ phases precipitate during subsequent aging, which reduces the quench sensitivity of the alloy.

Nitrogen is an alloying element that can significantly improve the yield strength of steel by means of interstitial solid solution strengthening. The effects of quenching temperature on the evolution of second phase and grain size were investigated, as well as tensile properties, impact energy and hardness of a new nitrogen-alloyed Fe-Cr-Mo-V-N steel. The results show that with the increase of quenching temperature, the number and size of the second phase decrease as the high temperature promotes the dissolution and refinement of the second phase. For instance, the number of second phase M23C6 particles decreases gradually with temperature increasing. When the quenching temperature reaches 1050 °C, the grain is refined. Under the same tempering treatment, with the increase of quenching temperature, the tensile properties, impact energy and hardness increase first and then decrease. When the quenching temperature is 1050 °C and the tempering temperature is 180 °C, the obtained mechanical properties are the best. Under this condition, the tensile strength at room temperature is 2110 MPa, the yield strength is 1620 MPa, and the impact energy is 29.1 J, respectively.

The phase diagram of the Na2O-ZrO2 system was experimentally investigated using the classical equilibration/quenching method and differential thermal analysis (DTA) followed by electron probe microanalysis (EPMA) and X-ray diffraction (XRD) phase analysis. For the first time, the general feature of the phase diagram between Na2ZrO3 and ZrO2 above 1773 K was revealed experimentally. The eutectic reaction between NaZrO3 and cubic-ZrO2 was found at 64.8 mol % ZrO2 at 1883 ± 3 K. Cubic-ZrO2 was stabilized by the dissolution of Na2O (maximum solubility of 7.1 mol % Na2O at 1883 ± 3 K). Based on new experimental phase diagram data in this study and thermodynamic property data of Na2ZrO3 in the literature, the Na2O-ZrO2 system was thermodynamically optimized using the CALculation of PHAse Diagram (CALPHAD) method and a consistent set of the Gibbs energy functions for all phases in the binary system was prepared.

Water‐dispersible and fluorescence‐stable carbon quantum dots (CQDs) have been synthesized at gram scale using pyrene as carbon precursor by employing the bottom‐up approach. X‐ray diffraction, FTIR, Raman spectroscopy and UV visible spectroscopy confirm the formation of CQDs. TEM images shows that size of the CQDs ranges from 2 to 5 nm. A detailed study of their optical and fluorescence characteristics was performed. Their aqueous dispersion radiates bright yellow light under UV lamp (365 nm). The research work includes derivation of their excitation wavelength, observation of influence of dilution on fluorescence and monitoring of emission intensity for about 4 months. The CQDs can effectively recognize the presence of heavy metal ions in aqueous medium at neutral pH via fluorescence quenching.

55Cr17Mo1VN high nitrogen martensitic stainless steel is usually applied to the high-quality mold, which is largely produced by the pressurized electro slag remelting process. The microstructure evolution of quenching and tempering heat treatment were investigated and an optimal heat treatment process to achieve excellent mechanical properties was found out. The main precipitates in the steel included carbon-rich type M23C6 and nitrogen-rich type M2N. With increasing austenitizing temperature, the equivalent diameter of the precipitates got fined, and retained austenite content increased significantly when the austenitizing temperature exceeded 1020 °C. The fracture mode gradually changed from brittle fracture to ductile fracture with increasing tempering temperature from 200 to 550 °C. The experimental steel tempered at 350 °C achieved a good combination of hardness (60.6 HRC) and strength (2299.2 MPa) to meet service requirements. Flake M23C6 precipitated along martensite lath boundaries and the secondary hardening phenomenon occurred when the tempering temperature was 450 °C. Due to the high nitrogen content, M2N precipitated from the inside of laths and matrix when tempered at 550 °C.

Quenching and partitioning (Q&P) treatment is a novel method to produce advanced high strength steel with excellent mechanical properties. In this study, combination of multiple-cyclic annealing and Q&P process was compared with traditional cold-rolled Q&P steel to investigate the microstructural characteristics and austenite retention. The results showed that retained austenite in traditional Q&P sample was principally located in the exterior of austenite transformation products, while those in multiple-cyclic annealing samples were mainly distributed inside the transformation products. With the increase in cyclic annealing number, both of austenite fraction and austenite carbon content increased, attributing to higher initial austenite carbon content and larger number of austenite/neighbored phase interface to act as carbon partitioning channel. In traditional Q&P sample, the deformed ferrite was recrystallized by sub-grain coalescence, while the austenite was newly nucleated and grew up during annealing process. As a comparison, the ferrite in multiple-cycle annealing samples was formed by means of three routes: tempered martensite that completely recovered with retention of interior martensite variant, epitaxial ferrite that formed on basis of tempered martensite, ferrite that newly nucleated and grew up during the final annealing process. Both of lath martensite and twin martensite were formed as initial martensite and then tempered during partitioning process to precipitate e carbide with C enrichment, Mn enrichment and homogeneous Si distribution. Compared with the traditional cold-rolled Q&P steel, the Q&P specimens after multiple-cyclic annealing show smaller strength and much larger elongation, ascribing to the coarser microstructure and more efficient transformation induced plasticity (TRIP) effect deriving from retained austenite with high carbon content and larger volume fraction. The application of double annealing treatment can optimize the mechanical properties of Q&P steel to show a striking product of strength and elongation as about 29 GPa%, which efficiently exploit the potential of mechanical performance in low carbon steel.

Carbon diffusion at the solid–liquid interface is of fundamental importance in scrap melting. Herein, the scrap microstructure at the melt interface and the carbon and silicon distributions are described using optical microscopy and electron microprobe analysis (EPMA). The microstructural path from the surface to the interior of the scrap was primary carbide → acicular martensite → dislocation martensite (original structure). The corresponding carbon concentration gradient was > 4 wt.% → 1–1.5 wt.% → 0.2 wt.%. This was consistent with the observed microstructural changes. Furthermore, the depth of the carbon diffusion layer was 200 μm and 220 μm at 1300°C and 1350°C, respectively. The silicon-enriched layer may be a retarding factor for carbon dissolution. The area of the austenite phase region in the Fe-Fe3C phase diagram was reduced owing to the presence of silicon. Therefore, acicular martensite formed after water quenching decreased, which reduced the thickness of the carburized layer.

A composite TiZrNiCuBe metallic glass/NiCrAl-bentonite coating was prepared on TC4 titanium alloy. Thermal shock testing of the coating was investigated by soaking at 600 °C for 10 min then quenching in cold water. Samples were extracted after 1, 50, 100, and 150 cycles to analyze the microstructure and oxidation behavior of the coatings. Microstructure characterization was carried out by scanning electron microscopy with energy-dispersive x-ray spectroscopy, and oxidation products were identified by x-ray diffraction analysis. The results showed that stress release in the metallic glass layer during heat treatment caused formation of cracks, around which oxidation occurred, leading to failure of the coating. The final oxidation products were TiO2, NiO, CuO, and ZrO2.

A newly developed spectrofluorometric method is based on the fabrication of an optical cyanopyridine derived sensor, 4-(6-diaryl)-2-oxo -1,2-dihydropyridine-3-carbonitrile using microwave irradiation. The fluorescence intensity of the proposed chemo sensor was obviously quenched in DMSO owing to the presence of UO22+ ions at λex/λem = 320/360 nm. The quenching effect of the cyano-derivative based sensor was found to be proportional to the concentration of UO22+ ion ranging between 9.60 × 10–9–5.28 × 10–5 mol L−1 with a detection and quantification limits of 1.71 × 10–11 and 5.2 × 10–11 mol L−1, respectively.

In the present study, the effect of the double quenching–tempering heat treatment on the mechanical properties of the HSLA-100 steel has been investigated. In this regard, the steel studied was first subjected to two consecutive austenitization treatments at 940°C and 870°C for 45 and 30 minutes, respectively, and quenching, followed by tempering in the temperature range of 510°C to 700°C for 60 min, and finally all the samples were cooled in air. Also, to compare the results with the conventional heat treatment cycle of this steel, some samples were subjected to single quenching–tempering. Furthermore, the variations of mechanical properties of HSLA-100 steel and the resultant microstructures were investigated in terms of different tempering conditions. Accordingly, it was found that the double quenching–tempering treatment could create a substantial difference in the total elongation percentage (+24%) of the samples by making minor changes in the strength parameters.

40Cr is essential to steel for the manufacture of hardened gears, and optimizing its laser quenching process will be of great significance for gear wear and life extension. However, the complete reliance on the experimental trial-and-error approach does not effectively reveal the mechanism of the evolution of the laser quenching process in disk laser. Numerical simulation provides an effective way to obtain the transient evolution of the laser quenching process. In this paper, the temperature changes physical parameters of the quenched material are calculated based on the CALPHAD method. Establish a thermo-elastic–plastic multi-field coupling model for the laser hardening process of the disk laser 40Cr gear steel. Perform the numerical calculations on the transient temperature, martensite phase fraction, and the transformation-induced plasticity stress evolution of the 40Cr laser hardening process. Focus on the mechanism of the mutual coupling between phase change behavior and plastic strain. Calculations show that there is heat accumulation during quenching, with a peak temperature of 1448 K. Plastic stress has a “hump” distribution, with a peak value of 834 MPa, which is 1.25 mm from the center of the focal point. The experimental analyses of the 40Cr gear steel quenching microstructure and hardness distribution state by the Axioskop2 scanning electron microscope, the KEYENCE VH-Z100R super depth of field 3D microscope, and the Q10M microhardness tester reveal the mechanical behavior of the material and the phase hardening law during the quenching process. That provided an essential theoretical basis for effective prediction on quenching residual stress and optimizing industrial production parameters.

A metallurgical and technological characterization of a seventh century seax coming from the Lombard necropolis of Campo San Giovanni in Leno (Brescia, northern Italy) was carried out to investigate the smithing technology involved in the blade manufacturing process. At first, a metric-based typological investigation of the seax was performed. X-ray radiography was used to gain a preliminary non-destructive technological assessment of the object. Optical microscopy and Vickers hardness measurements have allowed a metallurgical and mechanical characterization of the metal matrix both at the upper and lower blade portion. The results show that the seax blade was forged using different steel bars and also hypereutectoid steel. In addition, a selective quenching was performed by the ancient blacksmith to enhance the cutting-edge hardness. Scanning electron microscopy coupled with X-ray dispersive spectroscopy was employed to determine the chemistry of a large sample of nonmetallic inclusions entrapped within the metal matrix. A multivariate statistical analysis of the inclusions compositional data was used to carefully examine the composite nature of the artefact and trace the origin of the seax steel.

The steel 42CrMo4 with improved machinability was studied. The steel containing high amount of sulfur was calcium treated during metallurgical production stage. The size and area distribution of non-metallic inclusions present in the studied steel was analyzed and compared to the conventional Cr–Mn–Mo steels with low sulfur and calcium content. The dilatometric investigation was performed to reveal the features of the austenite transformations in studied Cr–Mn–Mo steels with various content of alloying elements. The mechanical properties of the high and low sulfur steels were analyzed in heat treated condition (oil quenching and tempering). The results proved that calcium treated 42CrMo4 steel with high sulfur content possessed almost the same characteristics of hardenability and mechanical behavior as the conventional low-sulfur steels. This implies that the steel with improved machinability can be successfully applied for the production of the heavy duty and high strength parts using automated lines and machines.

An experimental study has been carried out to determine the compositions of the slag/matte/metal/tridymite phases in equilibrium in the Cu-Fe-O-S-Si system at 1200℃. The measurements covered the full range of matte compositions from copper-free mattes to white metal, i.e. from 0 to 80 wt% of copper in matte. The research methodology involved high-temperature equilibration, quenching of the samples and accurate measurement of the phase compositions by electron probe X-ray microanalysis. The oxygen concentrations in mattes were directly measured using the EPMA. A comprehensive set of experimental equilibrium data has been obtained for coexisting matte, slag, Cu-Fe metal alloy and Fe-Cu metal alloy phases. It has been shown that solid iron-copper alloys were present at matte grades below 56 wt% Cu, while liquid copper-iron alloys were formed for matte grades higher than 56 wt% Cu. The experimental measurements have been compared with data reported in the literature and the trends calculated using the thermodynamic model descriptions of the system.

The mixing morphology control plays a crucial role in photovoltaic power generation, yet this specific effect on device performances remains elusive. Here, we employed computational approaches to delineate the photovoltaic properties of layered heterojunction polymer solar cells with tunable mixing morphologies. One-step quench and two-step quench strategies were proposed to adjust the mixing morphology by thermodynamic and kinetic effects. The computation for the one-step quench revealed that modulating interfacial widths and interfacial roughness could significantly promote the photovoltaic performance of layered heterojunction polymer solar cells. The two-step quench can provide a buffer at a lower temperature before the kinetic quenching, leading to the formation of small-length-scale islands connected to the interface and a further increase in photovoltaic performance. Our discoveries are supported by recent experimental evidence and are anticipated to guide the design of photovoltaic materials with optimal performance.

As a part of ongoing work on metal droplet dephosphorization, this study specifically investigated the effect of slag basicity (V ratio) by employing time lapse sampling while monitoring simultaneous decarburization using a constant volume pressure increase technique (CVPI) with X-ray fluoroscopy. The dephosphorization kinetics of droplets with two different initial carbon concentrations (2.51 and 0.007 wt pct), were tracked by quenching and analyzing droplets after different reaction times. The reaction kinetics were further elucidated by combining the decarburization rate of the droplet, measured via CVPI with the bloating behavior of droplet observed in-situ by X-ray fluoroscopy. The results showed that for high carbon droplets the dephosphorization rate increased with increasing slag basicity largely due to the increasing droplet decarburization rate, which enhanced mass transport of phosphorus by CO bubble stirring. Further increasing slag basicity increased the peak decarburization rate, but did not appear to further increase droplet dephosphorization. In low carbon droplets, the dephosphorization rate was also increased with increasing slag basicity because of the higher phosphorus partition ratio and larger mass transfer parameter $$kA$$ resulting from the faster oxygen transfer in the slag causing an increase in the interfacial area for reaction.