Search Results (737)

This study presents a solvothermal approach starting from micron-sized hydroxide precursors, which combines features of top-down size reduction and bottom-up recrystallization, leading to nanoscale hydroxide particles. The method is based on autoclave treatment at a moderate temperature (180 °C) and a pressure of 8 bar, using different mixtures of water and isopropanol. The hydroxide precursors, used in micrometric form without surfactants or additives, were converted into nanoscale particles through a one-pot, one-step process. The nanomaterials obtained were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), optical microscopy (MO), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) surface area analysis to assess their structural, morphological and textural characteristics. The results show that solvent composition and precursor concentration strongly influence the crystalline phase, particle morphology, dispersion stability and surface area. Well-defined acicular and fibrous morphologies were obtained for Ba(OH)₂ and Sr(OH)₂, while Mg(OH)₂ formed spherical and hexagonal structures, respectively. Of all the conditions tested, the 75:25 water/isopropanol ratio produced the most stable systems. This work provides a method to produce alkaline earth hydroxide nanoparticles with tunable properties. Full article

The increasing demand for enhanced wear resistance and mechanical integrity in tooling applications has driven the development of advanced surface engineering strategies for high-alloy steels. Böhler K390 MICROCLEAN, a powder-metallurgical V–Cr–Mo–W cold work tool steel with high vanadium content, features a composite metal matrix–carbide microstructure, consisting of uniformly distributed coarse vanadium carbides and finer carbides (M₇C₃, M₆C/MC) embedded in a ferritic matrix. This study investigated the effects of non-melting laser surface treatment (LST) applied to both as-received and bulk heat-treated K390 specimens. Microstructural characterization using SEM, EBSD, XRD, and EDX revealed the formation of a hardened surface layer comprising a structureless mixture of ultrafine-grained martensite and retained austenite, localized around vanadium carbides. Lattice parameter analysis and Williamson–Hall evaluation demonstrated increased carbon content, lattice distortion, and crystallite size reduction, contributing to high dislocation density (6.4 × 10¹⁴ to 2.6 × 10¹⁵ m⁻²) and enhanced hardness. Microhardness was increased by up to 160% compared to the initial state (reaching 835–887 HV₂₀), and dry-sliding testing showed up to 3.94 times reduced volume loss and decreased friction coefficients. Wear occurred via the formation and delamination of thin oxide tribo-layers, which enhanced the wear behavior. The combined approach of bulk heat treatment followed by LST produced a graded microstructure with superior mechanical stability, offering clear advantages for extending tool life under severe contact loads in stamping and forming operations. Full article

A chromium/amorphous carbon (Cr/(Cr/a-C)ml) nanostructured multilayer coating with a chromium sublayer was deposited on 42CrMo4 (1.7225,BDS EN ISO 683-2:2018), 100Cr6 (1.3505, BDS EN ISO 683-17:2024), and HS18-0-1 (1.3355, BDS EN ISO 4957:2018) alloy steels, selected for their use in contact-loaded components subjected to cyclic fatigue and intense wear. The coating was sputter deposited by MF pulsed magnetron sputtering under consistent process parameters. The resulting coating, approximately 1.8 μm thick, can significantly enhance the service life of these components. Adhesion was evaluated via the Daimler–Benz test, while coating homogeneity was confirmed through energy-dispersive spectroscopy, revealing a consistent chemical composition across sample surfaces. Raman spectroscopy indicated a high sp³/sp² ratio, confirming a dominant diamond-like carbon structure. Nanoindentation measurements verified the coating’s hardness, aligning with the observed structural properties. These results validate the process parameters for depositing a Cr/(Cr/a-C)ml coating on these alloy steels, achieving this study’s objectives. Full article

The Laoliwan Ag-Pb-Zn deposit is situated in the southern margin of the North China Craton and represents the first large-scale Ag-Pb-Zn ore deposit discovered in the Xiaoshan District. Ag-Pb-Zn orebodies are structurally controlled by NW- and NNW-trending faults and primarily hosted within early Cretaceous granite porphyry intrusions. In this study, sulfide Rb-Sr isotope dating and C-H-O-S-Pb multiple isotope compositions were conducted to constrain the ore genesis of this deposit. The Rb-Sr isotopic data of sulfides yield a weighted mean isochron age of 132.8 ± 9.5 Ma and an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.7115 ± 0.00016, indicating that mineralization occurred during the early Cretaceous and the ore-forming materials were derived from a crust–mantle mixed reservoir. The δ¹³ C (−1.3‰ to 0.7‰), δD (−96.3‰ to −86.7‰) and δ¹⁸O_H2O (0.3‰ to 5.6‰) values suggest that the ore-forming fluids were mainly derived from magmatic water with a contribution of meteoric water during mineralization. The δ³⁴S values of sulfides (+2.0‰ to +5.8‰) indicate a magmatic source. The Pb isotope data (²⁰⁶Pb/²⁰⁴Pb = 17.301–17.892, ²⁰⁷Pb/²⁰⁴Pb = 15.498–15.560, ²⁰⁸Pb/²⁰⁴Pb = 37.873–38.029) also reveal that the ore-forming materials originated from the lower crust with a small amount from the mantle source. By integrating geochronological and geochemical data, this study proposes that the Laoliwan Ag-Pb-Zn deposit is characterized as an epithermal deposit, with potential for the discovery of concealed porphyry Cu-Mo mineralization at depth. It is inferred to be related to tectonic–magmatic–fluid activities in the context of early Cretaceous lithospheric thinning along the southern margin of the North China Craton. Full article

This study reviews and experimentally investigates critical logistics and transport models in stainless-steel (SS) fluid storage tanks, focusing on stainless steel grades 316 and 304L. Conceptual vessel schematics emphasize hygienic drainability, refill uniformity, and thermal control, supported by representative 316L properties for heat-transfer, stress, and fluid–structure analyses. At the logistics scale, modelling integrates component-level simulations, computational fluid dynamics (CFD), and Finite Element Method (FEM) with network-level approaches, such as Continuous Approximation, to address facility location, refilling schedules, and demand variability. Experimental characterization using EDS and XRF confirmed the expected Cr/Ni backbone and grade-consistent Mo in 316, while unexpected C, Mn, and Cu readings were attributed to instrumental limits or statistical variance. Unexpected detection of Europium in 304L highlights the need for further mechanical testing. Overall, combining simulation, logistics modelling, and compositional verification offers a coherent framework for safe, efficient, and thermally reliable stainless-steel tank design. Full article

In concentrated solar power (CSP) systems, structural materials face severe corrosion challenges induced by molten chlorides, with the corrosion severity being highly dependent on the salt composition. This study systematically compares the corrosion behavior of two representative superalloys, Inconel 625 and SS321, in binary NaCl–KCl and ternary MgCl₂–NaCl–KCl molten salts at 700 °C. The corrosion products and microstructural features were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS), and electron backscatter diffraction (EBSD), in combination with static exposure tests to elucidate the underlying mechanisms. The results show that in NaCl–KCl molten salts, both alloys primarily form Cr₂O₃ as the protective product. However, the corrosion scale of SS321 is porous, whereas Inconel 625 develops a dense NiCr₂O₄ inner layer, exhibiting superior corrosion resistance. In the MgCl₂–NaCl–KCl molten salt system, Cr₂O₃ is replaced by a dense MgO layer forms on Inconel 625, coupled with Mo surface enrichment, which significantly inhibits Cr depletion and leads to a notably reduced corrosion rate relative to the binary salt. In contrast, the transformation of Cr₂O₃ on SS321 into porous MgCr₂O₄ exacerbates intergranular corrosion, resulting in a substantial degradation of corrosion resistance. This study elucidates the distinct corrosion pathways and mechanisms of different alloys in binary and ternary chloride salts, providing important guidance for the selection of molten salt compositions and corrosion-resistant structural materials in CSP applications. Full article

MXenes, a rapidly emerging family of two-dimensional transition metal carbides and nitrides, have attracted considerable attention in recent years for their potential in next-generation energy storage technologies. In solid-state batteries (SSBs), they combine metallic-level conductivity (>10³ S cm⁻¹), adjustable surface terminations, and mechanical resilience, which makes them suitable for diverse functions within the cell architecture. Current studies have shown that MXene-based anodes can deliver reversible lithium storage with Coulombic efficiencies approaching ~98% over 500 cycles, while their use as conductive additives in cathodes significantly improves electron transport and rate capability. As interfacial layers or structural scaffolds, MXenes effectively buffer volume fluctuations and suppress lithium dendrite growth, contributing to extended cycle life. In solid polymer and composite electrolytes, MXene fillers have been reported to increase Li⁺ conductivity to the 10⁻³–10⁻² S cm⁻¹ range and enhance Li⁺ transference numbers (up to ~0.76), thereby improving both ionic transport and mechanical stability. Beyond established Ti-based systems, double transition metal MXenes (e.g., Mo₂TiC₂, Mo₂Ti₂C₃) and hybrid heterostructures offer expanded opportunities for tailoring interfacial chemistry and optimizing energy density. Despite these advances, large-scale deployment remains constrained by high synthesis costs (often exceeding USD 200–400 kg⁻¹ for Ti₃C₂T_x at lab scale), restacking effects, and stability concerns, highlighting the need for greener etching processes, robust quality control, and integration with existing gigafactory production lines. Addressing these challenges will be crucial for enabling MXene-based SSBs to transition from laboratory prototypes to commercially viable, safe, and high-performance energy storage systems. Beyond summarizing performance, this review elucidates the mechanistic roles of MXenes in SSBs—linking lithiophilicity, field homogenization, and interphase formation to dendrite suppression at Li|SSE interfaces, and termination-assisted salt dissociation, segmental-motion facilitation, and MWS polarization to enhanced electrolyte conductivity—thereby providing a clear design rationale for practical implementation. Full article

This study evaluates the impact of mineralogy, elemental composition, and reaction pathways on hydrogen (H₂) generation in seven ultramafic and mafic (basaltic) rocks. Experiments were conducted under typical low-temperature hydrothermal conditions (150 °C) and captured early and evolving stages of fluid–rock interaction. Pre- and post-interactions, the solid phase was analyzed using X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS), while Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to determine the composition of the aqueous fluids. Results show that not all geologic H₂-generating reactions involving ultramafic and mafic rocks result in the formation of serpentine, brucite, or magnetite. Our observations suggest that while mineral transformation is significant and may be the predominant mechanism, there is also the contribution of surface-mediated electron transfer and redox cycling processes. The outcome suggests continuous H₂ production beyond mineral phase changes, indicating active reaction pathways. Particularly, in addition to transition metal sites, some ultramafic rock minerals may promote redox reactions, thereby facilitating ongoing H₂ production beyond their direct hydration. Fluid–rock interactions also regenerate reactive surfaces, such as clinochlore, zeolite, and augite, enabling sustained H₂ production, even without serpentine formation. Variation in reaction rates depends on mineralogy and reaction kinetics rather than being solely controlled by Fe oxidation states. These findings suggest that ultramafic and mafic rocks may serve as dynamic, self-sustaining systems for generating H₂. The potential involvement of transition metal sites (e.g., Ni, Mo, Mn, Cr, Cu) within the rock matrix may accelerate H₂ production, requiring further investigation. This perspective shifts the focus from serpentine formation as the primary driver of H₂ production to a more complex mechanism where mineral surfaces play a significant role. Understanding these processes will be valuable for refining experimental approaches, improving kinetic models of H₂ generation, and informing the site selection and design of engineered H₂ generation systems in ultramafic and mafic formations. Full article

Ferritic/martensitic (F/M) steel is a candidate material for key structures in fourth-generation nuclear energy systems (such as fusion reactors and fast reactors). Irradiation hardening behavior is a core index to evaluate the material’s stable performance in a high-neutron-irradiation environment. In this study, based on 2048 composition and property data, a correlation model between key elements and their interactions and irradiation hardening in F/M steel was constructed using a Bayesian optimization neural network, which realized quantitative prediction of the effect of composition on hardening behavior. Studies have shown that the addition of about 9.0% Cr, about 0.8% Si, Mo content higher than about 0.25%, and the addition of Ti, Mn can effectively suppress the irradiation hardening of F/M steel, while the addition of N, Ta, and C will aggravate its irradiation hardening, and the addition of W and V has little effect on the irradiation hardening of F/M steel. There is an interaction between the two elements. C-Cr has a strong synergistic mechanism, which will cause serious hardening when the content is higher than 0.05% and the Cr content is higher than 10%. Cr-Si has a strong antagonistic mechanism, which can achieve the comprehensive irradiation hardening effect in the 9Cr-0.8Si combination. N-Mn needs N controlled lower than 0.01%. Mo-W needs to control Mo content higher than 0.5% to alleviate irradiation hardening. There is a weak synergistic effect in Si-V; when the content is between 0.3% and 0.8% and the V content is between 0.2% and 0.3%, it can assist in optimizing the composition of F/M steel. Through the optimization of multi-element combination, the composition of F/M steel with lower irradiation hardening can be designed. Full article

Cobalt–molybdenum $\eta$-carbides are attractive hydrodesulfurization (HDS) catalysts, yet controlling their phase composition and nanostructure remains challenging. Here, a ${\mathrm{Co}}_{25}{\mathrm{Mo}}_{25}{\mathrm{C}}_{50}$ powder was prepared by mechanical alloying in a horizontal mill, with and without superimposed vertical vibration. Phase composition was determined by X-ray diffraction using the reference-intensity-ratio method, and the nanostructure was examined by SEM and HRTEM. Aquathermolysis of a heavy crude was monitored by ATR-FTIR in the window characteristic of S–S and C–S vibrations. Both milling routes produced the $\eta$-carbides ${\mathrm{Co}}_3{\mathrm{Mo}}_3$C and ${\mathrm{Co}}_6{\mathrm{Mo}}_6$C, as well as ${\mathrm{Co}}_2{\mathrm{Mo}}_3$, ${\mathrm{Co}}_7{\mathrm{Mo}}_6$, and ${\mathrm{Co}}_3$C; vibration-assisted milling increased the ${\mathrm{Co}}_6{\mathrm{Mo}}_6$C fraction and generated thin lamellae exhibiting Moiré contrast. In FTIR, the ${\mathrm{Co}}_6{\mathrm{Mo}}_6$C-rich powder showed strong attenuation of the disulfide and thioether bands, whereas the ${\mathrm{Co}}_3{\mathrm{Mo}}_3$C-rich powder behaved similarly to the water-only baseline under mild conditions (100 °C, 4 h). These results indicate that mechanical alloying with superposed vibration enables control over phase and nanostructure, and that a higher ${\mathrm{Co}}_6{\mathrm{Mo}}_6$C fraction correlates with a stronger HDS response under aquathermolysis. The approach offers a scalable route to Co–Mo carbides that are active for desulfurization at 100 °C in water without added ${\mathrm{H}}_2$. Full article

Copper matrix self-lubricating composites are critical for high-temperature industrial applications. In this study, Cu-Ni-Sn-Mo-Gr composites with 3–7 wt.% graphite were fabricated via spark plasma sintering (SPS). The influence of graphite content on microstructure, mechanical properties, and tribological behavior from room temperature (RT) to 500 °C were systematically investigated. The results demonstrate that increasing graphite content progressively reduces density, hardness, and yield strength, whereas it significantly enhances high-temperature tribological performance. The composites with 7 wt.% graphite addition achieve outstanding self-lubricity and wear resistance across the RT-500 °C, achieving an average friction coefficient of 0.09 to 0.21 and a wear rate of 1.32 × 10⁻⁶ to 7.52 × 10⁻⁵ mm³/N·m. Crucially, temperature-dependent lubrication mechanisms govern performance: graphite-dominated films enable friction reduction at RT, while synergistic hybrid films of graphite and in situ-formed metal oxides (Cu₂O, CuO, NiO) sustain effective lubrication at 300–500 °C. Full article

Organic solvent nanofiltration (OSN) is a promising technology for solute removal from organic media, yet developing membranes with stable separation performance remains challenging. This study presents a solvent-resistant double-crosslinked nanofiltration membrane fabricated via a two-step strategy: preparation of the membrane by the polyion complexion reaction-assisted non-solvent-induced phase inversion (PIC-assisted NIPS) method and then post-crosslinking with hydrothermal treatment followed by quaternization with 1,3,5-tris(bromomethyl)benzene (TBB). To enhance solvent stability, molybdenum sulfide (MoS₂) nanosheets were incorporated into a hydrolyzed polyacrylonitrile (H-PAN) substrate. The H-PAN/MoS₂/PEI base membrane was fabricated by PIC-assisted NIPS with a polyethylenimine (PEI) aqueous solution as the coagulation bath. The membrane subsequently underwent dual crosslinking comprising hydrothermal treatment and 1,3,5-tris(bromomethyl)benzene (TBB)-mediated quaternization crosslinking, ultimately yielding the H-PAN/MoS₂/PEI (Ther.+TBB QCL) composite membrane. These crosslinking procedures reduced the membrane’s separation skin layer thickness from 64 nm (uncrosslinked) to 41 nm. The resultant membrane effectively separated dyes from ethanol, achieving a rejection rate of 97.0 ± 0.9% for anionic dyes (e.g., Congo Red) and a permeance flux of 23.6 ± 0.2 L·m⁻²·h⁻¹·bar⁻¹ at 0.4 MPa. Furthermore, after 30 days of immersion in ethanol at 25 °C, its flux decay rate was markedly lower than that of a non-crosslinked control membrane. The enhanced separation performance and stability are attributed to the thermal crosslinking promoting amide bond formation and the TBB crosslinking introducing quaternary ammonium groups. This double-crosslinking strategy offers a promising approach for preparing high-performance OSN membranes. Full article

The stability and mechanical properties of (TiZrHf)_1−x(AB)_x (AB = NbTa, NbMo, MoTa) refractory high-entropy alloys have been investigated by combining the first-principles with special quasi-random structure (SQS) method. It is found that with the increase in solute concentration x, the ΔH_mix of (TiZrHf)_1−x(AB)_x (AB = NbMo, MoTa) linearly decreases, whereas both ΔH_mix and ΔS_mix of (TiZrHf)_1−x(NbTa)_x increase initially and subsequently decrease, with the crossover occurring at x = 0.56. The ΔH_mix of (TiZrHf)_1−x(NbTa)_x and (TiZrHf)_1−x(AB)_x (AB = NbMo, MoTa) alloys are larger and lower than that of TiZrHf, respectively, while the ΔS_mix of all (TiZrHf)_1−x(AB)_x is larger than that of TiZrHf. The formation possibility parameter Ω of all (TiZrHf)_1−x(AB)_x (AB = NbMo, MoTa) first decreases sharply, followed by a gradual decrease. And the local lattice distortion (LLD) parameter δ remains relatively stable around x = 0.56 for all cases, after which it decreases sharply until x = 0.89. The δ value of (TiZrHf)_1−x(AB)_x is higher than that of TiZrHf for x < 0.56 but becomes lower beyond this composition. The valence electron concentration (VEC), a possible indicator for a single-phase solution, of (TiZrHf)_1−x(AB)_x increases nearly linearly, while the formation energy ΔH_f of (TiZrHf)_1−x(AB)_x shows the opposite tendency, except for (TiZrHf)_0.67(NbTa)_0.33. Furthermore, the VEC of all (TiZrHf)_1−x(AB)_x alloys increases, whereas their ΔH_f decreases compared to that of TiZrHf. The ideal strength σ_p of (TiZrHf)_1−x(AB)_x increases linearly, reaching approximately 2.12 GPa. The bulk modulus (B), elastic modulus (E), and shear modulus (G) also exhibit linear increases, and their values in all (TiZrHf)_1−x(AB)_x alloys are higher than those of TiZrHf, with some exceptions. The Cauchy pressure (C₁₂–C₄₄) and Pugh’s ratio G/B of all (TiZrHf)_1−x(AB)_x alloys increase, whereas the Poisson’s ratio ν exhibits the opposite trend. Moreover, the C₁₂–C₄₄ and G/B ratio of TiZrHf are lower and higher, respectively, than those of (TiZrHf)_1−x(AB)_x, and the ν of TiZrHf is lower than that of (TiZrHf)_1−x(AB)_x. This study provides valuable insights for the design of high-performance TiZrHf-based refractory high-entropy alloys. Full article

This study addresses the need for sustainable, high-performance photocatalytic materials by developing novel polylactide (PLA)/MXene composites. A one-step plasma-liquid synthesis method was employed, utilizing a direct current discharge between metal electrodes (Ti, Mo) in a carbon tetrachloride and PLA solution. This single-step process simultaneously exfoliates MXene nanosheets (Ti₂CCl_x, Mo₂CCl_x, Mo₂TiC₂Cl_x) and incorporates them into the polymer matrix. The resulting composite films exhibit a highly porous morphology and significantly enhanced optical absorption, with band gaps reduced to 0.62–1.15 eV, enabling efficient visible-light harvesting. The composites demonstrate excellent photocatalytic activity for degrading a mixture of organic dyes (Methylene Blue > Rhodamine B > Reactive Red 6C) under visible light. The developed plasma-liquid technique presents a streamlined, efficient route for fabricating visible-light-driven PLA/MXene photocatalysts, offering a sustainable solution for advanced water purification applications. Full article

The crystal structure of caysichite-(Y) from the Ploskaya Mt (Kola Peninsula, Russia) has been refined to R₁ = 0.051 for 4472 unique observed reflections. The mineral is orthorhombic, Ccm2₁, a = 13.2693(3), b = 13.9455(4), c = 9.7384(2) Å, V = 1802.06(8) ų, Z = 4. There are two M sites predominantly occupied by Y, but also including Ca and other rare earth elements (REEs). Both M sites are coordinated by eight O atoms to form distorted bicapped trigonal prisms. The crystal structure is based upon a three-dimensional framework formed by columns of MO₈ polyhedra and (CO₃) groups and double-crankshaft chains of SiO₄ tetrahedra running parallel to the c-axis. The topology of linkage of MO₈ polyhedra understood in terms of the M–M links shorter than 5 Å corresponds to the M network with the paracelsian (pcl) topology. The channels in the network are occupied by double-crankshaft Si chains and H₂O groups. The new general chemical formula of a caysichite-(Y)-type mineral can be written as [Y_2+2x−y′Ca_{2−3x−y″}☐_x+y′+y″][Si₄O₁₀](HCO₃)_3y′+2y″(CO₃)_{3−3y′−2y″}·(4−z)H₂O, where z ~ 0.2; x ≤ 2/3; y′ ≤ 2/3; y″ ≤ 1; 3y′+2y″ ≤ 2. This general formula allows for several end-member formulas according to different x, y′ and y″ values: (Y₂Ca₂)[Si₄O₁₀](CO₃)₃·4H₂O (x = y′ = y″ = z = 0), (Y₂Ca☐)[Si₄O₁₀](HCO₃)₂(CO₃)·4H₂O (x = y′ = z = 0; y″ = 1), (Y_10/3☐_2/3)[Si₄O₁₀](CO₃)₃·4H₂O (y′ = y″ = z = 0; x = 2/3), Ca₂Y_4/3☐_2/3)[Si₄O₁₀](HCO₃)₂(CO₃)·4H₂O (x = y″ = z = 0; y′ = 2/3). The samples studied in this work have the compositions (REE_2.05Ca_1.87☐_0.18)[Si₄O₁₀](HCO₃)_0.11(CO₃)_2.89·3.8H₂O (x = 0.025, y′ = 0, y″ = 0.055) and (REE_2.25Ca_1.52☐_0.23)[Si₄O₁₀](HCO₃)_0.21(CO₃)_2.79·3.8H₂O (x = 0.125, y′ = 0, y″ = 0.115). The end-member formula most close to these compositions is (Y₂Ca₂)[Si₄O₁₀](CO₃)₃·4H₂O, which is different from the formula (Ca,Yb,Er)₄Y₄(Si₈O₂₀)(CO₃)₆(OH)·7H₂O currently adopted by the International Mineralogical Association but is generally identical to the formula (Y,Ca)₄Si₄O₁₀(CO₃)₃·4H₂O proposed in the original study of the mineral. In order to resolve the problem of the caysichite-(Y) formula, additional studies of materials from different localities (and, especially, one from the holotype locality) are needed. Full article