Search Results (10,142)

Aluminum alloy capsules play a critical role in shape control, heat transfer, and pressure transmission during the PM-HIP sintering of Al-based powders. As the weakest part of the capsule, the reliability of the welded joint is crucial for the safe operation of the HIP process and the quality of the final product. This study investigated the effects of two typical HIP temperatures on the evolution of second phases and texture. The results show that: (1) At 400 °C, suppressed Si diffusion retains a continuous, low-melting-point Al-Si eutectic network and needle-like secondary phases in the weld zone, thereby impeding residual stress relief. Compositional segregation in the heat-affected zone weakens grain boundary stability. The texture undergoes only limited recovery, with a strong <100> orientation retained and micro-strain not effectively relieved, restricting joint ductility. (2) At 510 °C, Si is sufficiently spheroidized, forming a bead-like structure. Needle-like second phases transform into globular/short-rod morphologies, disrupting the continuity of the brittle phases. Simultaneously, complete recrystallization is induced, resulting in a randomized texture and significant release of micro-strain, thereby improving microstructural homogeneity and plastic deformation capacity. This study suggests that the internal stress concentration arising from the low-melting-point eutectic phase and strong texture poses a failure risk for the capsule. Therefore, employing the 510 °C HIP process to achieve second-phase spheroidization and texture weakening can significantly mitigate this failure risk. Full article

In this study, isothermal annealing of AA8014 aluminum alloy burst vents was performed at 250–500 °C for 10 s to 2 h, and Johnson–Mehl–Avrami–Kolmogorov (JMAK) kinetic analysis was employed to determine the recrystallization parameters at 300 °C. An Avrami exponent of n = 1.87 and an apparent activation energy of Q = 156 kJ/mol were obtained, revealing a recrystallization mechanism driven by high stored energy and synergistically regulated by particle-stimulated nucleation at coarse second-phase particles and Zener pinning by fine Al(Fe,Mn)Si dispersoids. The burst pressure evolution was highly temperature-dependent: annealing at or below 300 °C led to sluggish recrystallization and a gradual pressure decline, whereas annealing at 350 °C and above resulted in recrystallization completion within 10 s and a sharp pressure drop to a stable plateau of approximately 0.92 MPa. The Al(Fe,Mn)Si dispersoids showed no significant differences in size distribution or grain-boundary pinning after 1 h at both 300 °C and 500 °C. This invariance across the tested range rendered the microstructure and burst performance insensitive to process variations. A quantitative predictive model correlating the recrystallized fraction with the burst pressure was established, with prediction errors less than 4.1%. The 300–350 °C interval is identified as the critical temperature window for regulating recrystallization kinetics and burst pressure, providing a rational basis for the heat-treatment design of burst vents. Full article

This review presents a current understanding of the relationship between the structure of multicomponent metallic melts and the processes of amorphization and nanocrystallization. Particular attention is paid to the thermal-temporal treatment (TTT) of melts as a precision method for monitoring the nonequilibrium state of the liquid phase, the relaxation kinetics of cluster associations, and liquid–liquid transitions (LLT). The mechanisms by which precrystallization melt treatment affects the homogeneity of the amorphous precursor, the size of nanograins (7–15 nm), the phase composition (Fe₃Si, Fe₂B), and the resulting magnetic characteristics of toroidal cores (μ_max > 600,000, H_c < 0.5 A/m) are investigated. Based on an analysis of structural models of metallic melts (cybotactic, quasicrystalline, and quasichemical), it is shown that critical temperatures, viscosity hysteresis, and oscillatory relaxation serve as indicators of melt equilibrium. It is noted that the optimized TTT protocols combined with controlled annealing at 542–572 °C enable the formation of Fe₃Si nanograins with exceptional magnetic softness. The results open the possibility of discussing the prospects for integrating TTT with in situ diagnostics, CALPHAD modeling, and the potential of machine learning for the design of next-generation soft magnetic nanomaterials with tailored frequency characteristics for high-frequency power electronics and their use in electromagnetic shielding. Full article

With the continuous increase in horizontal displacement during unconventional oil and gas drilling, drilling operations are commonly plagued by high frictional resistance, severe pipe sticking issues and difficulties in directional drilling. Conventional single-component water-based drilling fluid lubricants fail to satisfy multifunctional demands, including high-temperature resistance, salt tolerance and long-term lubrication. In this work, a novel microsphere lubricant, RB-Si, with high-temperature and high-salinity resistance was developed by combining the merits of solid and liquid lubricants. The product was synthesized using myristic acid and triethanolamine as raw materials via co-reaction with boric acid and nano-silica. Laboratory tests reveal that after aging at 180 °C, the lubrication coefficient reduction rates of based mud, saturated salinity-based mud and a high-density (2.0 g/cm³) drilling fluid gel system containing 1.0 wt% RB-Si reached 90.1%, 83.3% and 62.8%, respectively. Meanwhile, RB-Si can effectively plug the micropores in the filter cake, reduce fluid loss, inhibit shale hydration and swelling, and exhibit excellent compatibility with drilling fluids. RB-Si rapidly adsorbs onto the surfaces of metallic drill strings and formation rocks to construct a durable and high-strength lubricating film, accompanied by the rolling friction of the incorporated microspheres, thereby reducing frictional drag between the drill string/casing and the drill string/borehole wall. This lubricant effectively mitigates high frictional resistance under prolonged friction conditions, and is expected to provide technical support for long-horizontal-well drilling. Full article

Silicon carbide (SiC) in its various structural modifications is widely used in power semiconductor electronics, operating under extreme conditions of high temperature, high voltage, and intense radiation. The discovery of spin defects (S > 0) with unique optical and coherent properties has further positioned SiC as a promising platform for quantum technologies. Here, we investigate a 6H-SiC single crystal co-doped with nitrogen and beryllium at concentrations of 10¹⁸ cm⁻³, using continuous-wave and pulsed electron paramagnetic resonance (EPR) and electron–nuclear double resonance (ENDOR). To enhance spectral resolution, experiments were conducted in the W-band (94 GHz; B = 3.4 T). Pulsed EPR identified nitrogen donors and beryllium acceptors in various lattice positions, allowing for the determination of their phase coherence and spin–lattice relaxation times. ENDOR measurements elucidated the electron–nuclear interactions with the local silicon and carbon environment, including distant coordination spheres. The observed hyperfine structures indicated highly delocalized spin density within the supercell. The TRIPLE resonance spectra verify coupled nuclear spin subspaces from different coordination spheres due to defect spin density. These results demonstrate the feasibility of incorporating dual impurities with distinct functional roles while preserving the crystal lattice’s structural features. Full article

Remaining useful life (RUL) prediction of power semiconductor devices plays a crucial role in reliability design and predictive maintenance of power control system. This article introduces a data-driven methodology on predicting the RUL of the gate oxide layer in silicon carbide (SiC) MOSFETs. Firstly, a power cycling platform is established to collect the time-varying curves of threshold voltage and construct an aging dataset. Then, the successive variational mode decomposition (SVMD) algorithm is employed to adaptively decompose the signal of gate threshold voltage, helping suppress measurement noise and fluctuations caused by operating conditions while retaining degradation features. Subsequently, a Temporal Convolutional Network (TCN) is adopted to capture temporal dependencies in the degradation sequence, thereby improving the characterization of gate oxide health status assessment. Finally, the extended Kalman particle filter (EKPF) is employed to estimate the degradation state and quantify the associated uncertainty by recursively fusing model predictions with real-time measurements. The proposed method integrates the adaptive signal decomposition capability of SVMD, the temporal feature extraction capability of TCN, and the uncertainty quantification capability of EKPF. Their complementary integration improves prediction accuracy and robustness in gate oxide degradation evaluation for SiC MOSFET. Full article

Single-event burnout (SEB) remains a persistent threat to SiC power MOSFETs in space, yet rapid evaluation of SEB susceptibility without costly heavy-ion campaigns is challenging. This work demonstrates that femtosecond laser two-photon absorption (TPA) can fill that role for a commercial 1200 V SiC MOSFET—provided the laser energy is correctly mapped to heavy-ion linear energy transfer (LET). We derive an equivalent LET model that incorporates the thermal spike effect, giving LET_eq = Γ₁E₀² + Γ₂E₀⁴, which corrects the classical square law at high excitation intensities where it fails. Three ionization-driven failure signatures emerge: drain-to-gate and drain-to-source single-event leakage current (SELC), and SEB. The SEB threshold saturates near 500 V once LET exceeds 25 MeV·cm²/mg—roughly 42% of the device’s 1200 V rating. From these thresholds, we define a safe operating area: below 200 V is safe, 200–600 V risks SELC degradation, and above 600 V carries high SEB risk. Benchmarking against published heavy-ion data shows SEB threshold agreement within 15%, and within 5% at high LET. We stress that the TPA method captures ionization-driven effects only; it does not replicate displacement damage. These results support rapid, laser-based screening of SiC power devices for radiation hardness. Full article

Assessing projected hydrological scenarios from a risk perspective facilitates water governance and management. This study, framed in an informed and contextualized potential impact assessment process, evaluates the physical sensitivity to climate change on low flows and droughts, in a water supply sector, for illustrative purposes. More specifically, we evaluated 28 neutral scenarios using the WaSiM-ETH model on six catchments in Quebec, Canada. Guided by CORDEX—RCP 8.5 projections, the 28 scenarios are constructed around seven annual temperature changes ranging from 0 °C to 6 °C and four non-uniform monthly changes in precipitation ranging from −10% to +20%. The results show, for example, that for a scenario involving a 10% increase in precipitation and a 3 °C rise in temperature, the low flows reductions (7Q2) would range from 15% to more than 30%, the deficit in water volume during the droughts would increase by 2- to 3-fold, and the duration would vary little. No clear correlation was found between low flows and drought behaviour, with each catchment responding individually to the same climatic changes. This study thus advocates a tailored and context-specific methodology to operationalize risk assessment and make water resource management more efficient. Full article

High-output-current boron-doped diamond (B-diamond) metal–oxide–semiconductor field-effect transistors (MOSFETs) with a modulated boron-doped epitaxial layer were fabricated. An intrinsic diamond epitaxial layer was deposited on the single-crystal diamond substrate as a buffer layer, and plasma-enhanced chemical vapor deposition (PECVD) SiO₂ was employed as both the gate dielectric and passivation layer. The boron-doped epitaxial layer has a thickness of approximately 500 nm and a boron concentration in the range of 10¹⁷–10¹⁸ cm⁻³. The B-diamond MOSFETs showed clear p-channel operation, with a maximum output current of −0.18 mA/mm at room temperature. When the temperature was increased to 150 °C, the maximum output current increased to −1.05 mA/mm, while the on-resistance decreased from 413.91 to 12.13 kΩ·mm. The on/off ratio remains approximately 10⁵ over the measured temperature range. In addition, the device exhibited a breakdown voltage of −347 V at a gate-to-drain spacing of 12.5 μm, and the simulation results showed that the peak electric field was mainly concentrated near the drain-side gate edge of the passivation layer. These results indicated that, for the B-diamond MOSFETs, a balanced epitaxial layer thickness and boron concentration were essential for achieving sufficient channel conduction as well as effective gate control ability. Full article

This study investigates the effects of phosphorus (P) on the phases developed during sintering and their impact on the stability of key phases in iron ore sinter, particularly the silico-ferrite of calcium and aluminum (‘SFCA’) series of phases. Two complementary systems were studied: an industrially representative blend of natural iron ores (JSM) and a synthetic high-purity SFCA analogue (SA) system designed to promote controlled SFCA formation. Phosphorus was added as hydroxyapatite (HA) at levels of 0.5, 1.0, 1.5 and 5 wt.%. To simulate a standard sintering profile, experiments were conducted over a range of temperatures for 3 min in a controlled low-oxygen-potential atmosphere of pO₂ = 5 × 10⁻³ atm. A modified Bond Abrasion test was used to evaluate the tumble index (TI) strength of the samples, and the chemistry, mineralogy and microstructure of all sintered products were analyzed. Results indicated that all P-doped JSM samples fired within the temperature range of 1300 to 1330 °C met the minimum strength requirement (TI = 80%) for producing high-quality sinters. Adding small to medium amounts of HA (≤1.5 wt.%) to both compositions had a limited impact on the overall mineral phases. Conversely, adding a high amount of HA (5 wt.%) encouraged the creation of Ca–Si–P phases. Analysis of the microstructure, minerals, and microchemistry indicated that P tended to segregate phases rich in phosphorus by interacting with calcium oxide and silica. The findings from the study highlight that at the low levels of P typically found in iron ores, there is no significant impact on the strength, mineralogy and phases formed during sintering. Full article

Saline–alkali stress severely restricts cucumber (Cucumis sativus L.) growth by disrupting ion balance, water status, photosynthesis, and redox homeostasis. Here, we examined the effects of exogenous selenium (Se) on cucumber seedlings exposed to NaHCO₃ stress. Se supplementation improved plant growth and root activity and partly restored photosynthetic performance by maintaining chlorophyll content, gas exchange, and chlorophyll fluorescence. Se reduced oxidative injury through lower ROS and MDA levels and by enhancing antioxidant enzyme activities together with the AsA–GSH cycle. In parallel, Se moderated ion toxicity by limiting Na⁺ accumulation, increasing K⁺, Ca²⁺, and Mg²⁺ uptake, and stimulating H⁺-ATPase and H⁺-PPase activities. Enhanced TCA cycle activity and organic acid accumulation suggested improved energy metabolism and ionic regulation. Se also promoted osmotic adjustment via soluble sugars and proline, and upregulated aquaporin genes (PIP1;2 and PIP2;4) to sustain water transport. Moreover, Se increased salicylic acid levels by upregulating CsPAL and CsICS, pointing to a role of SA signaling in Se-induced tolerance. Full article

Dye wastewater pollution has become a critical environmental issue, while conventional silica adsorbents are often limited by high production costs and the use of chemical silicon sources. In this study, a black-liquor-derived silica-based adsorbent was prepared from bamboo alkaline black liquor through calcium hydroxide precipitation, acid leaching, washing, and calcination. The obtained product was systematically characterized by ICP-OES, XRD, SEM, and BET analysis. Phase analysis showed that the product was mainly composed of amorphous SiO₂, together with a small amount of residual CaSiO₃. The product was semi-quantitatively estimated to contain approximately 64.6 wt.% total SiO₂ and 14.7 wt.% total CaSiO₃, and the estimated SiO₂ yield was about 4.6 wt.% based on dry black liquor solids. The adsorbent exhibited a mesoporous structure with a specific surface area of 60.04 m²/g, a pore volume of 0.23 cm³/g, and an average pore diameter of 7.5 nm. The effects of adsorbent dosage, initial methylene blue concentration, solution pH, and temperature on adsorption performance were investigated. Under the selected conditions of 0.5 g adsorbent, 50 mg/L methylene blue, pH 7, and 20 °C, the removal efficiency reached 82.94%. Adsorption isotherm analysis showed that the Langmuir equation provided the best fit among the tested models over the studied concentration range, and the linear Langmuir fit gave an apparent capacity parameter of 840.3 mg/g. However, this fitted value should not be interpreted as a physically realizable ideal monolayer uptake. This work provides a feasible route for converting silicon-containing bamboo alkaline black liquor into a mesoporous silica-based adsorbent for dye removal. Full article

Interconnector geometry strongly affects gas transport, polarization loss, and pressure drop in planar solid oxide fuel cells (SOFCs). In this study, four interconnector configurations were investigated for an anode-supported planar SOFC, including one conventional straight-rib interconnector and three connected-rib interconnectors, namely circular-rib (CI), rectangular-rib (RI), and triangular-rib (TI) designs. A three-dimensional multi-physics model coupling electric field, flow field, species transport, and temperature field was established and validated against experimental polarization data of the conventional straight-rib cell. To ensure a fair comparison, all interconnectors were designed with the same interconnector–electrode contact area. The effects of rib configuration on electrical performance, overpotential components, reactant distribution, velocity distribution, and pressure drop were systematically analyzed. At 800 °C, the peak power densities of CI-SOFC, RI-SOFC, and TI-SOFC increased by 4.9%, 9.7%, and 11.7%, respectively, compared with SI-SOFC. The connected-rib interconnectors mainly reduced cathode-side activation and concentration overpotentials by improving oxygen redistribution beneath the ribs. Among the four configurations, the TI-SOFC showed the highest power density and the strongest under-rib transport enhancement, while the RI-SOFC provided a better compromise between flow uniformity and pressure drop. Full article

Different flat-panel detector technologies are available for intraoperative fluoroscopy. This study compared orthopedic and trauma surgeons’ preference and subjective image quality among mobile C-arm systems equipped with amorphous silicon (a-Si), complementary metal oxide semiconductor (CMOS) or indium gallium zinc oxide (IGZO) detectors. Fluoroscopic imaging was performed on four human specimens at four anatomic locations at pulse rates of 1/s and 10/s in low- and high-dose settings using three C-arm systems. Subjective image quality was rated by two observers on 5-point Likert scales. Pairwise forced-choice comparisons of images with identical acquisition parameters were analyzed using a Bradley–Terry model. Across all images, CMOS- and IGZO-based systems were preferred over the a-Si-based system in 91.8% and 90.4% of comparisons, respectively (ORs 9.53 and 11.20; both p < 0.001). No significant overall preference was observed between the IGZO- and CMOS-equipped systems. Subjective image quality ratings were significantly higher for CMOS- and IGZO-based systems compared with the a-Si-based system, particularly for overall image quality and perceived noise, while no consistent differences in image quality were found between CMOS- and IGZO-based systems. Overall, the CMOS- and IGZO-based systems evaluated in this study were preferred over the a-Si-based system and achieved superior subjective image quality ratings. Full article

Thermochemical conversion of nitrogen- and sulfur-rich biomass-derived wastes, such as sewage sludge, algae, and agricultural residues, is a promising route for renewable fuel production and waste valorization. However, fuel-bound nitrogen can be released as NH₃, HCN, and HNCO, while sulfur species such as H₂S, SO₂, and COS accelerate catalyst deactivation and generate NO_x/SO_x precursors. Metal-loaded ZSM-5 catalysts are attractive for clean catalytic pyrolysis because they combine the MFI pore confinement and tunable Brønsted/Lewis acidity of ZSM-5 with the hydrogen transfer, dehydrogenation, cracking, redox, and sulfur-tolerance functions of metal species. This review critically summarizes recent advances in metal-loaded ZSM-5 catalysts for catalytic denitrogenation of biomass-derived solid wastes. The formation and migration of NH₃, HCN, HNCO, tar-N, and char-N are first discussed to clarify the chemical basis of fuel-N conversion. The effects of ZSM-5 pore structure, acid-site distribution, Si/Al ratio, hierarchical porosity, and synergy on adsorption, diffusion, C-N bond cleavage, heterocyclic-N ring-opening, aromatization, and nitrogen redistribution are then analyzed. Catalyst deactivation under realistic pyrolysis atmospheres is also highlighted, including coke deposition, metal sintering, framework dealumination, mineral poisoning, and H₂S/SO₂/COS-induced sulfur poisoning. Finally, future directions are proposed for designing multifunctional ZSM-5-based catalysts integrating denitrogenation activity, sulfur resistance, coke resistance, regenerability, and quantitative nitrogen/sulfur mass balance. Full article