Search Results (2,796)

Laser powder bed fusion (LPBF) technology offers an effective approach for fabricating high-performance superelastic NiTi alloys. This study achieved Ni_51.9Ti_48.1 alloys with outstanding superelastic properties through a triple optimization design of the initial powder composition, printing process parameters, and post-processing. The phase transformation behavior and microstructure of the alloys were systematically investigated. The results indicate that as energy density increases, the size and quantity of pore defects in LPBF-fabricated Ni_51.9Ti_48.1 alloys increase, phase transformation temperatures rise, and hardness conversely decreases. Ni_51.9Ti_48.1 alloys produced at lower energy densities exhibit fewer dislocations. After annealing at 600 °C, Ni₄Ti₃ and R phases form internally, resulting in a maximum superelasticity of 6.64%. Conversely, Ni_51.9Ti_48.1 alloys produced at higher energy densities exhibited a large number of dislocations and formed subgrains after annealing at 600 °C. Additionally, due to the high void volume fraction, they demonstrated deteriorated superelasticity. Full article

The influence of Cu addition on the age-hardening response, mechanical properties, and precipitation evolution of Si-rich Al–Mg–Si alloy was investigated by hardness test, room-temperature tensile test, and transmission electron microscopy analysis. The results indicate that the addition of Cu significantly enhances the aging–hardening response of the alloy, promotes the hardness and room-temperature tensile strength under the peak-aged state, and reduces the softening rate during over-aging. The peak-aged tensile strength of the Cu-added alloy (387 MPa) was approximately 9% higher than that of the Cu-free alloy (355 MPa), and the elongation to failure of the Cu-added alloy reached 19%, significantly exceeding the 15% exhibited by the Cu-free alloy. The Cu promotes the precipitation of under-aged and peak-aged β″ strengthening phases within the alloy grains, while also facilitating the formation of lath-shaped Q’ and L phases in peak-aged and over-aged microstructures. This enhances the room-temperature tensile properties of the alloy in the peak-aged state and reduces the attenuation of over-aged properties. Furthermore, Cu influences grain boundary precipitation behavior by promoting the formation of Cu-rich precipitates along grain boundaries and reducing the width of precipitation-free zones (PFZs). Full article

The high-temperature and hot corrosion behavior of Diamalloy 2002 coatings with a WC/Co–NiCrFeBSiC composite structure applied to a 316 L stainless steel surface using the atmospheric plasma spraying (APS) method was investigated. The coatings were held at 900 °C in air for 5, 25, 50, and 100 h and in a molten salt bath of Na₂SO₄ + V₂O₅ at 900 °C for 1, 3, and 5 h. SEM, EDS, and XRD analyses revealed that the oxide layer on the surface thickened with increasing temperature and corrosion duration, forming NiO, Cr₂O₃, and mixed metal oxides. These oxide phases created a protective barrier effect by limiting diffusion between the coating and the substrate. Despite a slight increase in porosity and minor WC dissolution under long-term oxidation conditions, the coatings maintained their structural integrity up to 900 °C, demonstrating significant resistance to high-temperature oxidation and molten salt corrosion. These results demonstrate that Diamalloy 2002 coatings provide an effective surface protection solution in abrasive and oxidizing high-temperature environments. Full article

Cracks in laser-cladded coatings represent a critical challenge that severely limits their industrial deployment. In this study, high-frequency pulsed direct current-assisted electrically assisted heat treatment (EAHT) was applied to repair cracks in laser-cladded Ni60/WC coatings deposited on 45# medium carbon steel. The influence of current density and treatment duration on crack arrest and healing behavior was systematically investigated. Dye penetrant testing and scanning electron microscopy (SEM) were employed to characterize the morphology and evolution of cracks before and after EAHT, while hardness, fracture toughness, and wear resistance tests were conducted to evaluate the mechanical properties. The results revealed that the crack repair process proceeds through three distinct stages: internal filling, nucleation and growth of healing points, and complete crack closure. The combined effects of Joule heating and current crowding induced by EAHT significantly facilitated progressive crack healing from the bottom upward. Optimal crack arrest and healing were achieved at a current density of 6.25 A/mm², resulting in a maximum fracture toughness of 10.74 MPa·m^1/2 and a transition of the wear mechanism from spalling to abrasive wear. This study demonstrates that EAHT promotes selective crack-tip heating and microstructural regulation through thermo-electro-mechanical coupling, thereby markedly enhancing the comprehensive performance of Ni-based WC coatings. Full article

This study evaluated the influence of niobium addition and austempering time and temperature on the microstructure and mechanical behavior of ductile iron. Three alloys were produced: unalloyed ductile iron (H1) and two Nb-alloyed ductile iron (H2, 0.11 wt.% Nb and H3, 0.32 wt.% Nb). After austenitizing at 900 °C for 60 min, samples were austempered at 250 °C and 300 °C for 15, 30, 60, and 90 min. The as-cast microstructure of H3 exhibited a higher pearlite fraction (73.31 vol%) and increased carbide content (2.48 vol%), accompanied by reduced nodularity and nodule count. X-ray diffraction analysis revealed that the highest fraction of carbon-rich retained austenite was obtained in H3 after 30 min at 300 °C, reaching 42.48%. Hardness decreased with increasing retained austenite, confirming the inverse relationship between this phase and matrix strengthening. Wear testing showed that H2 presented slightly lower volume loss due to carbide precipitation, with the lowest value recorded after 15 min at 300 °C (1.088 mm³). Tensile tests indicated that ultimate tensile strength and yield strength were superior at 250 °C, with H3 achieving the highest values at 90 min (1353 and 1090 MPa, respectively). Overall, niobium promoted carbide formation and austenite stabilization, modifying the balance between hardness, toughness, and wear resistance in austempered ductile iron. Full article

The dynamics of dense colloidal systems are not fully understood. In the study of these types of systems, computer simulations based on the so-called hard sphere model play a significant role. In the presented work, we consider a system of hard spheres of the same size but different mobilities (molecules with high mobility correspond to solvent molecules, while molecules with reduced mobility are colloid particles) at varying concentrations. For this purpose, a two-dimensional lattice and an thermal model of such systems was designed. In order to determine the properties of such systems, a Monte Carlo computer simulation was used, employing the Dynamic Lattice Liquid (DLL) algorithm. Our main aim was to determine how the dynamic behavior of the system in the short time affects the long-time behavior. For this purpose, we investigated the cross-ratios of the diffusion coefficients in the short and long time of the considered system elements. It was found that the reduction in the solvent mobility with increasing concentration of colloidal particles in a short time leads to a very similar reduction in the mobility of the colloid particles in a long time, but we do not observe such behavior in the case of the solvent, i.e., there is a decrease in the value of the solvent diffusion coefficient in the long time with the change in the concentration of colloid particles, but it is difficult to connect it in a simple way with the decrease in the diffusion coefficient in the short time. Full article

This study explores a novel approach to enhance the surface properties of Ti-Al alloys for biomedical applications by creating a compositional gradient layer through aluminum deposition using Electrical Discharge Machining (EDM). The primary goal was to develop a metallurgically bonded intermetallic zone that supports strong adhesion and improved compatibility for subsequent hydroxyapatite (HA) deposition. Aluminum was deposited onto a Ti6Al4V substrate via EDM under controlled conditions, followed by thermal and thermochemical treatments to induce diffusion and intermetallic phase formation. Comprehensive analyses using optical and electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) revealed the formation of well-adhered layers composed of complex Ti-Al intermetallics such as TiAl₂ and TiAl₃, along with oxide phases including TiO₂ and Al₂O₃. Thermal and thermochemical treatments further improved surface hardness, reaching up to 1057 HV, and influenced the diffusion behavior of aluminum, titanium, and vanadium. Adhesion tests confirmed that the untreated and thermochemically treated layers exhibited superior mechanical stability, while thermal treatment alone led to brittleness and delamination. These findings demonstrate that a properly engineered intermediate aluminide layer can significantly improve the performance of bioceramic coatings, particularly HA, by providing enhanced structural integrity and biocompatibility. Full article

Coastal Bangladesh faces severe drinking water scarcity due to salinity intrusion. To address this challenge, the study assesses the socio-technical and economic factors shaping the performance of small-scale reverse osmosis (RO) desalination plants through field audits, household surveys, stakeholder interviews, and water quality analysis. Community acceptance was evaluated using the Theory of Planned Behavior (TPB). Feedwater was highly contaminated, with average TDS 3732.63 mg/L, hardness 636.36 mg/L, iron (Fe) 3.23 mg/L, and turbidity 14.63 NTU. Despite this, RO systems demonstrated strong performance, achieving removal efficiencies of 95.15% for salts, 95.95% for hardness, and 91.67% for alkalinity, with an average recovery rate of 37.25% (range: 20–60%). Treated water met WHO and Bangladesh standards, with mean concentrations of TDS (195.54 mg/L), Fe (0.21 mg/L), arsenic (0.0085 mg/L), and turbidity (1.09 NTU). However, inadequate operator training and a lack of maintenance threaten sustainability. Energy consumption increased by 0.1 kWh/m³ per 1000 mg/L rise in salinity, while financial constraints hinder membrane replacement. TPB analysis revealed positive attitudes and perceived behavioral control as key adoption drivers. Untreated brine discharge (mean TDS 12,900 mg/L) posed significant environmental risks. This study provides micro-level insights to inform policy and strengthen the sustainability of decentralized RO systems in climate-vulnerable coastal regions. Full article

Lignin-derived hard carbon (LHC) has emerged as a highly promising anode material for sodium-ion batteries (SIBs), owing to its renewable nature, structural tunability, and notable electrochemical properties. Although considerable advancements have been made in the development of LHCs in recent years, the absence of a comprehensive and critical review continues to impede further innovation in the field. To address this deficiency, the present review begins by examining the intrinsic characteristics of lignin and hard carbon (HC) to elucidate the underlying mechanisms of LHC microstructure formation. It then systematically categorizes the synthesis strategies, structural attributes, and performance influences of various LHCs, focusing particularly on how feedstock characteristics and fabrication parameters dictate final material behavior. Furthermore, optimization methodologies such as feedstock pretreatment, controlled processing, and post-synthesis modifications are explored in detail to provide a practical framework for performance enhancement. Finally, informed recommendations and future research directions are proposed to facilitate the integration of LHCs into next-generation SIB systems. This review aspires to deepen scientific understanding and guide rational design for improved LHC applications in energy storage. Full article

This study presents a gradient boosting-based machine learning (ML) approach developed to predict cutting speed and feed rate in band sawing operations. The model was built using a dataset of 1701 experimental samples from three industrially common material types: AISI 304, CK45, and AISI 4140. Each sample was defined by key process parameters, namely, material type, a hardness range of 15–44 HRC, and a diameter range of 100–500 mm, with cutting speed and feed rate as target variables. Five ML models were examined and compared in this study, including linear regression (LR), support vector regression (SVR), random forest regression (RFR), least squares boosting (LSBoost), and extreme gradient boosting (XGBoost). Model training and validation were carried out using five-fold cross-validation. The results show that the XGBoost model offers the highest accuracy. For cutting speed estimation, the performance values of XGBoost are an RMSE of 0.213, an MAE of 0.140, an R² of 0.999, and an MAPE of 0.407%; and for feed rate estimation, an RMSE of 0.259, an MAE of 0.169, an R² of 0.999, and a MAPE of 1.14%. These results indicate that gradient-based ensemble methods capture the nonlinear behavior of cutting parameters more effectively than linear or kernel-driven techniques, providing a practical and robust approach for data-driven optimization in intelligent manufacturing. Full article

The present study evaluated the effects of psyllium mucilage (PM) added at levels of 0.25% (PM 0.25), 0.5% (PM 0.5), and 0.75% (PM 0.75), compared to guar gum (GG) and carob gum (CAR), on the rheological properties, overrun, melting, and consumer acceptance of vegan yogurt-based ice (yog-ice) creams. Rheological analysis showed that all formulations exhibited non-Newtonian, shear-thinning behavior (n < 1), although the magnitude varied depending on the hydrocolloid used. PM significantly (p < 0.05) increased viscosity in a concentration-dependent manner, reaching 585.3 mPa·s for PM 0.75, and improved yield stress and structural stability. CAR addition resulted in the lowest apparent viscosity (41.8 mPa·s) but the strongest pseudoplasticity (n = 0.328), whereas GG yielded moderate viscosity. PM ice creams exhibited the lowest extent of melting (1.20 g/g at PM 0.75) and the longest first dripping time (67.2 min). PM addition reduced lightness (L*) and increased redness (a*), with higher levels producing perceptible differences (ΔE > 5). CAR increased hardness (42.2 N), while PM 0.25 and PM 0.5 decreased it (28.9 and 33.9 N). Consumer evaluation confirmed that PM 0.5 achieved the highest overall acceptability (7.58), comparable to GG (7.61), whereas CAR and PM 0.75 reduced scores. Psyllium mucilage thus represents a promising clean-label stabilizer for plant-based yog-ice creams, enhancing melting resistance, textural quality, and sensory appeal at optimal concentrations. Full article

The rapidly growing demand of electric vehicle (EV) charging is one of the main challenges to modern electrical distribution systems. Accurate modelling of the EV charging load is crucial for charging load prediction and optimization. However, previous methods based on the charging behaviors of private EVs are hard to collect user’s private data. In this study, charging load data from 962 charging and battery swapping stations (CBSSs), classified into dedicated charging stations, public charging stations, and battery swapping stations, collected during 2021–2022, are analyzed to investigate seasonal variations in the charging coincidence factor. A data-driven probabilistic model of charging load, based on the Gaussian Mixture Model, is developed to address various scenarios, including new station construction, capacity expansions, and optimized charging strategies. This model is applicable to different types of CBSSs. A real-world 10 kV feeder system is employed as a case study to validate the model, and a delayed charging strategy is proposed. The results demonstrate that the proposed model accurately estimates charging load peaks after new construction and expansion in 2023, with an error rate under 3%. Furthermore, the delayed charging strategy achieved a 24.79% reduction in maximum load and a 31.96% decrease in the peak–valley difference. Its implementation in the real-world feeder significantly alleviated nighttime overloading in 2024. Full article

The synthesis, reaction process, and mechanical properties of medium-entropy (TiVNb)₂AlC MAX phase materials were investigated. The Ti, V, Nb, Al, and C powders were mixed and sintered by the powder metallurgy method. The experimental results showed that the highest purity M₂AlC phase with a mass fraction of 95.8% was obtained when the raw material ratio was M(Ti:V:Nb):Al:C = 2:1.2:0.7 and the sintering temperature was 1450 °C. In order to explore the sintering process reactions and optimize the purity of sintered products, sintering was carried out under different temperatures and various molar ratios of raw materials. During the sintering process, the metal elements firstly reacted with aluminum to generate intermetallic compounds (IMCs), and with the increase in temperature, the IMCs gradually reacted with carbon to generate M₂AlC. Mechanical property tests revealed that the Vickers hardness of the medium-entropy (TiVNb)₂AlC material was 6.52 GPa, significantly higher than both the theoretical prediction based on the rule of mixtures and the hardness of traditional MAX phases. The severe lattice distortions in the polymeric solid solution structure contributed to this significant increase in hardness. In addition, the medium-entropy (TiVNb)₂AlC exhibited temperature-dependent friction behavior within the temperature range of room temperature to 400 °C, with the lowest friction coefficient observed at 200 °C when the sample was in contact with the bearing steel. This study provided an important theoretical and experimental basis for the synthesis and future application of medium-entropy MAX phase materials. Full article

A series of PTT-b-PTMG copolyesters was synthesized via direct esterification followed by melt polycondensation using purified terephthalic acid (PTA), bio-based 1,3-propanediol (PDO), and poly(tetramethylene glycol) (PTMG) of varying molecular weights (650–3000 g/mol). The resulting materials were comprehensively characterized in terms of chemical structure, molecular weight, thermal behavior, phase morphology, crystalline architecture, and mechanical performance using a range of analytical techniques: Fourier-transform infrared spectroscopy (FTIR), ¹H-NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), dynamic mechanical thermal analysis (DMA), tensile testing, and other standard physical methods. FTIR, ¹H-NMR, and GPC data confirmed the successful incorporation of both PTT-hard and PTMG-soft segments into the copolymer backbone. As the PTMG molecular weight increased, the average sequence length of the PTT-hard segments (L_n,T) also increased, leading to higher melting (T_m) and crystallization (T_c) temperatures, albeit with a slight reduction in overall crystallinity. DMA results indicated enhanced microphase separation between hard and soft domains with increasing PTMG molecular weight. WAXS and SAXS analyses further revealed that the crystalline structure and long-range ordering were strongly dependent on the copolymer composition and block architecture. Mechanical testing showed that tensile strength at break remained relatively constant across the series, while Young’s modulus increased significantly with higher PTMG molecular weight—concurrently accompanied by a decrease in elongation at break. Furthermore, the elastic deformability and recovery behavior of PTT-b-PTMG block copolymers were evaluated through cyclic tensile testing. TGA confirmed that all copolyesters exhibited excellent thermal stability. This study demonstrates that the physical and mechanical properties of bio-based PTT-b-PTMG elastomers can be effectively tailored by adjusting the molecular weight of the PTMG-soft segment, offering valuable insights for the rational design of sustainable thermoplastic elastomers with tunable performance. Full article

This study examines how diabetes mellitus and physiological aging influence the nanomechanical behavior of rat rib cortical bone using combined static and dynamic nanoindentation. Ribs from young control, old, and streptozotocin-induced diabetic rats were analyzed to quantify both intrinsic and frequency-dependent mechanical properties. Static nanoindentation revealed markedly higher hardness and elastic modulus in the diabetic group (0.47 ± 0.22 GPa and 9.53 ± 3.03 GPa, respectively) compared to controls (0.11 ± 0.03 GPa and 3.21 ± 0.51 GPa; p < 0.001). The modulus-to-hardness ratio, an indicator of fracture toughness, was reduced from 30.34 in controls to 20.45 in diabetics, suggesting increased stiffness but greater brittleness. Dynamic nanoindentation (0–4.5 Hz) demonstrated significant aging-related changes in the storage and loss moduli (p < 0.001), while the loss factor (tan δ < 1) and viscosity remained similar across groups, indicating predominantly solid-like behavior. These results show that diabetes stiffens bone tissue through matrix-level alterations, whereas aging primarily affects its viscoelastic damping capacity. The combined static–dynamic nanoindentation protocol provides a robust framework for distinguishing disease- and age-related bone degradation at the tissue scale. Translationally, the findings help explain why bones in diabetic or elderly individuals may fracture despite normal mineral density, underscoring the need to assess bone quality beyond conventional densitometry. Full article