Recycling high-performance glass fibers from waste wind turbine blades via an acetic acid/nitric acid system.

To address the issues of high cutting temperatures and severe tool wear during titanium alloy machining, this study proposes a hybrid surface modification strategy combining micro-textures and multicomponent titanium nitride (TiN)-based coatings on cemented carbide tools. Using YG8 cemented carbide as the substrate, micro-dimple textures were fabricated by fiber laser, and three coatings with different architectures (TiAlSiN, TiSiN/TiAlN, and TiSiN/TiAlSiN/TiAlN) were deposited via multi-arc ion plating technology. Based on a two-factor (texture diameter and texture spacing) and three-level orthogonal experiment, the evolution behaviors of surface morphology, phase composition, and mechanical properties of the textured multicomponent TiN-based coatings were systematically characterized and comparatively analyzed. The results reveal that: compared to the monolithic-structured TiAlSiN coating, the TiSiN/TiAlSiN/TiAlN and TiSiN/TiAlN composite coatings with multilayered composite structures can effectively relieve the residual stress inside the film–substrate system, and significantly suppress the phenomena of coating cracking and localized spallation caused by irregular protrusions of the recast layer at the micro-texture edges. X-ray diffraction (XRD) and crystallite size analyses indicate that the amorphous Si3N4 phase promoted by the Si element in the composite coatings effectively impedes the growth of TiN columnar crystals, achieving significant grain refinement. Mechanical property tests confirm that the existence of multicomponent composite interfaces effectively hinders dislocation movement. Among them, the textured TiSiN/TiAlSiN/TiAlN composite coating exhibits the optimal comprehensive performance; its microhardness, nanohardness, and H/E ratio (characterizing the resistance to plastic deformation) are increased by 17.94%, 8%, and approximately 45%, respectively, compared to those of the textured TiAlSiN coating. This study deeply elucidates the synergistic strengthening and toughening mechanisms between micro-texture parameters and the internal structures of the coatings, providing important theoretical guidance and experimental data support for the surface design of long-lifespan tools oriented towards the high-efficiency machining of titanium alloys.

Distinct roles of metalloid elements (Si, P, C) in tailoring as-quenched nanostructure and magnetic properties of Fe–B–Cu nanocrystalline alloys

The complementary strategy of Si and Ge elements in CSiGe monolayer as anode materials for sodium-ion batteries: First-principles insights

Geotourism sites often receive little attention from the general public as interesting object to visit. Tourists generally come just to enjoy the scenery. In addition, there are many geotourism sites that are less interesting to visit, even though they have high scientific value and a wealth of knowledge stored as natural laboratories. This research aims to package exploration data of interesting stones in transport igneous rocks and beach sand for exposure to enhance tourist attraction. In this research, magnetic and geochemical methods applies to igneous transport rocks and beach sand were subjected to geochemical and magnetic susceptibility tests to provide information to tourists about the geotourism object. The geochemical test was conducted using X-Ray Fluorescence (XRF), and resulting the presence of chemical elements Si, K, Ca, Ti, V, Cr, Mn, Fe, Cu, Eu, Re, Mo, and Zn. The dominant elements with a content of more than 5% (wt) are Si, Fe, and Ca, with average values of 56.78 wt%, 24.20 wt%, and 8.41 wt%, respectively. The high Si content confirms that the contribution of igneous rocks is more dominant in the beach sand compared to coral rocks. This implies that the plate subduction in that area is relatively deep. The magnetic susceptibility test shows a magnetic susceptibility value ranging from 13 to 4143 ×10-8 m 3 /kg, with average 1182 ×10-8 m 3 /kg indicate that igneous rocks and beach sand are rich in magnetic minerals that can be utilized as industrial raw materials. The exploration data was packaged as promotional materials and presented to tourists. In addition, perfectus and location videos are presented for public access. Finally, the research network was communicated to the general public and productive communities of tourism business owners and received positive feedback regarding the benefits of this research and activities.

The heavier Group 14 elements Si and Ge are known for their superior conductance performance over carbon in σ-channel-dominated molecular wires. Only a few studies have, however, explored their potential as C substitutes in wires with π-dominated conductance channels. We report a series of diarylamine (DA)-terminated π-conjugated wires, where C, Si, and Ge bridging atoms planarize a phenylene-vinylene linker. We find a slight impact on the conductance performance that deviates from the ordering according to atomic mass, with Si achieving a 20-30% higher conductance compared to Ge and C. DA oxidation increases conductance by 2 orders of magnitude and mitigates heteroatom-induced variations. Furthermore, the meta isomer of the Si analogue was synthesized in an effort to increase heteroatom participation in the conductance channel, revealing increased sensitivity to atomic substitution and considerable conductance at a 0.5 V bias.

This study explores the structural, morphological, optical,andgas-sensing characteristics of titanium dioxide (TiO2)thin films with thicknesses of 90, 130, and 160 nm, both before andafter decoration with gold (Au/TiO2) and silver (Ag/TiO2) nanoparticles. XRD confirmed the formation of the pure anatasephase, with crystallite size increasing from 13.7 to 14.7 nm and microstraindecreasing from 12.05 × 10–3 to 11.18 ×10–3 as film thickness increased. Scanning electronmicroscopy revealed a thickness-dependent grain growth (15.4 ±3–34.7 ± 4.5 nm), while the successful decoration withAu nanoparticles enlarged the particle size to 19 ± 3.5–37.9± 5 nm. EDX spectroscopy confirmed stoichiometric TiO2 composition, diffusion of substrate elements (Na, Ca, Mg, and Si),and controlled metal loading (Au: 5.8–10.3 wt %; Ag: 1.4–2.8wt %). Spectroscopic ellipsometry results indicated refractive indicesof 2.3–3.4 and optical band gaps between 3.44–3.60 eV,suggesting improved crystallinity and reduced defect density withincreasing thickness. Transmission spectroscopy under CO2 and air atmospheres revealed negligible response for bare glassand pure TiO2, whereas Au/TiO2 and Ag/TiO2 films exhibited localized surface plasmon resonance (LSPR)dips at 520–550 nm and 450–500 nm, respectively. UponCO2 exposure, Ag/TiO2 showed red-shifts of 10–15nm and transmission changes of 5–8%, while Au/TiO2 exhibited larger shifts (12–20 nm) and 6–10% modulation.Transmission change ratio analysis confirmed the superior sensitivityof Au/TiO2 (TCR up to −0.50) compared to Ag/TiO2 (TCR up to 0.20), demonstrating their potential for efficient,label-free optical CO2 sensing.

The strongly constrained and appropriately normed (SCAN) meta-generalized gradient approximation (meta-GGA) functional is a milestone achievement of electronic structure theory. Recently, a revised and restored form (r$^2$SCAN) has been suggested as a replacement for SCAN in high-throughput applications. Here, we assess the accuracy and reliability of the r$^2$SCAN meta-GGA functional for the group-IV elemental solids carbon (C), silicon (Si), germanium (Ge), and tin (Sn). We show that the r$^2$SCAN functional agrees closely with its parent functional SCAN for elastic constants, bulk moduli, and phonon dispersions, but the numerical stability of r$^2$SCAN is superior. Both meta-GGA functionals outperform standard GGA (Perdew-Burke-Ernzerhof) in terms of accuracy and approach the level of common hybrid functionals (Heyd-Scuseria-Ernzerhof). However, we find that r$^2$SCAN performs much worse than SCAN for the $α\leftrightarrow β$ phase transition of both Ge and Sn, yielding larger phase energy differences and transition pressures.

Abstract We present the first analysis of the X-ray Imaging and Spectroscopy Mission (XRISM) observation of the supernova remnant (SNR) N103B. We fit the X-ray spectrum taken with the Resolve microcalorimeter, which captured emission lines from the predominantly ejecta elements Si, S, Ar, Ca, Cr, Mn, and Fe. Notably, our fits require a previously unidentified high-temperature, highly ionized, Fe-dominated plasma component with particularly high Cr and Mn abundances, matching a feature also present in the recent XRISM analysis of the SNR N132D. We find that all ejecta in N103B exhibits significant line broadening arising mostly from thermal Doppler broadening: increasing from σ th ∼ 1700 km s −1 for intermediate-mass element (IME: Si, S, Ar, and Ca) ejecta to ∼2800 km s −1 for Fe-rich ejecta. These velocities correspond to reverse shock velocities of ∼3500 and ∼5900 km s −1 , respectively, in the ejecta frame of rest. Finally, we find that the IMEs are redshifted with a bulk velocity of ∼360 km s −1 while the Fe-dominated components are split: one redshifted at ∼1560 km s −1 and the other blueshifted at ∼1020 km s −1 . Our results provide further support for the double-ring structure of N103B as it expands into the bipolar winds of a nondegenerate companion and highlight the strength of high-resolution spectroscopic observations of SNRs.

Abstract Through characterization of the electronic excited-state topology, linear-SiCP is predicted to be photostable in the UV region, whereas linear-AlCP is predicted to undergo photodissociation to form Al+CP products after absorption of light in the 200–250 nm range, representing a catalytic process for freeing aluminum molecules from a solid dust grain. Both SiCP and AlCP are predicted to have electronic transitions with large absorption cross sections (∼10 –17 cm 2 ) and to undergo fluorescence from bound excited states. The total electronic absorption spectrum is provided to inform electronic spectroscopy experiments. Silicon (SiC) and aluminum (Al 2 O 3 ) dust grains are ubiquitous in the interstellar medium, and are especially prominent in the circumstellar envelopes of evolved stars such as VY CMa and IRC+10216. These regions of space are hotbeds for chemical activity, where reactions can occur on the surfaces of these dust grains to form new species. One such reaction that has been theorized involves the CP radical interacting with dust grain surfaces to produce the triatomic molecules SiCP and AlCP. To motivate and facilitate experimental and observational searches for AlCP, its ground-state spectroscopic properties (rotational and vibrational) have been investigated. The small permanent dipole moment (∼0.1 D) is expected to make radioastronomical observation difficult, although experimental detection may be feasible if a sufficiently large molecular number density can be achieved.

Context . Very metal-poor stars are important tracers of the early chemical evolution history of the Milky Way. Infrared H -band spectroscopic surveys, such as APOGEE, are less affected by extinction in the more dust-obscured environments of our Galaxy. However, H -band spectra contain very limited spectral information for stars at the most metal-poor tail ([Fe/H] < −2.5) because the available Fe lines in FGK stars in this wavelength range are weak. Aims . The first paper in this series successfully identified a sample of 327 very metal-poor stars (with [Fe/H] < −2) from the APOGEE database, 289 of which are on the red giant branch. The spectra of these stars were not properly analysed by the APOGEE main pipeline because they are very metal poor. In this work, we measure metallicities for these stars using the abundances of the elements Mg and Si. Methods . We demonstrate that the absorption lines of the elements Mg and Si are of good quality despite the challenging combination of (low) metallicity, wavelength regime, spectral resolution, and signal-to-noise ratios available for these spectra. A specialised pipeline was designed to measure the abundance of Mg and Si in APOGEE spectra and yielded a robust estimate of the overall metallicity. In order to provide reliable measurements, we tested three different sets of assumptions for Mg and Si enhancement. Results . We present Mg and Si abundances as well as overall metallicities for 327 stars, all of which had previously gotten null values from the main APOGEE pipeline for either the calibrated [M/H] or [Fe/H]. The typical uncertainties for our measurements are 0.2 dex. We found five stars in our sample with unusual [Si/Mg] abundances higher than 0.5, and we connect this signature to globular cluster stars, and this might be related to specific supernova events. Our data suggest a concentration of high [Si/Mg] stars in the Sextans dwarf galaxy. Other dwarf galaxies are found to agree well with results in the literature. Conclusions . Our derived metallicities range between −3.1 ≤ [M/H] ≤ −2.25, thereby pushing the metal-poor tail of APOGEE results down by 0.6 dex.

This study focused on an Al-Fe-Cr alloy system with a certain amount of Si (a major impurity in Al alloys) as a model for high-temperature alloys with an industrially produced composition suitable for laser-beam powder bed fusion (PBF-LB) processing. The phase equilibria and solidification sequence in the experimental alloy composition of Al-2.5Fe-2Cr-0.5Si (mass%) were analyzed via thermodynamic calculations. The gas-atomized alloy powder exhibited excellent processability in the PBF-LB process, resulting in the manufacture of fully dense alloy specimens with relative densities exceeding 99%. The PBF-LB-fabricated Al-Fe-Cr-Si alloy exhibited a melt-pool structure formed through repeated local melting and rapid solidification during scanning laser irradiation. Several grains containing high-density low-angle boundaries (sub-boundaries) were elongated along the building direction (BD) in the α-Al matrix with a crystallographic texture of <110>//BD. The relatively coarsened Al 11 Cr 2 phases were localized around the melt pool boundaries, whereas numerous nanosized particles of the Al 6 Fe metastable phase containing Si and Cr were dispersed within the melt pool interior. Consequently, the strength of the Al-Fe-Cr-Si alloy specimen was considerably higher than that of the Al-Fe binary alloys. However, the Al-Fe-Cr-Si alloy specimen exhibited significant ductility loss only in the direction perpendicular to the BD upon elevating the test temperature to 300 °C. The high-temperature embrittlement may be attributed to preferential fracture at many precipitates of the Si-rich intermetallic phase (presumably brittle) formed at the boundaries of the α-Al grains elongated along the BD. These results provide new insights into the design of alloy composition, including impurity elements, for controlling the high-temperature mechanical performance of Al-Fe multi-elemental alloys suitable for PBF-LB processing.

Abstract The increasing demand for improved mechanical properties in structural steels has driven innovations in welding techniques, particularly for low-carbon steels like ST 37. This study examines the effects of multilayer welding using the Metal Inert Gas (MIG) process on the hardness and microstructure of ST 37 steel. A three-layer welding configuration was applied using a constant current of 150 Amperes. The welded specimens were analyzed using Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS) and Vickers microhardness testing to evaluate the structural and mechanical changes in the weld metal, heat-affected zone (HAZ), and base metal. SEM analysis revealed the presence of ferrite and pearlite phases across all regions, with the weld metal exhibiting a higher concentration of pearlite and denser grain structure, indicative of increased hardness. EDS results confirmed the elemental composition, with iron as the dominant element, accompanied by carbon, manganese, silicon, and minor trace elements. The Vickers microhardness test showed the highest hardness value in the weld metal (216.28 HV), followed by the base metal (174.27 HV), and the HAZ (153.57 HV). These findings demonstrate that multilayer welding significantly influences the microstructural evolution and hardness profile of ST 37 steel. This study highlights the potential of multilayer MIG welding to enhance mechanical performance in low-carbon steels, offering valuable insights for applications requiring increased wear resistance and structural integrity.

Study on the effect for water quenching method in separating Si from metallurgical grade silicon refining slag

Abstract To quantitatively identify the environmental mitigation potential of crystalline silicon photovoltaic (PV) systems under the “dual-carbon” targets, this study applies a life-cycle assessment (LCA) approach to a 1 kWp multi-crystalline silicon grid-connected PV system. A cradle-to-end-of-life system boundary is established, covering metallurgical-grade silicon, solar-grade polysilicon, wafers, cells, modules, balance of system (BOS), and end-of-life recycling and disposal. Based on the ecoinvent database and the IMPACT 2002+ method, multiple environmental impact categories are selected to compare the production, use, and end-of-life stages. The results show that module production is the dominant source of environmental burdens, typically contributing 80%–90% of the total life-cycle impacts, while BOS components contribute around 10%. Under material-recycling scenarios, the end-oflife stage can reduce key indicators such as greenhouse gas emissions and fossil energy consumption by approximately 3%–7%. The study suggests that optimizing upstream energy-intensive processes, decarbonizing the electricity mix, and improving module recycling rates are key to further enhancing the life-cycle environmental performance of PV systems.

First-principles study of dehydrogenation on group IV elements Si, Ge, or Sn doped MgH2(110) surface

Research on the thermal conductivity and thermal expansion coefficient of TiAl3 ceramics: Influence of Si element and preparation methods

To promote the resource utilization of oilfield solid waste and facilitate the green and low-carbon transformation of transportation infrastructure, this study employed drilling cuttings from the Maye area of the Xinjiang oilfield and coal-fired furnace ash as primary raw materials. NaOH, Na2O·nSiO2, and Ca(OH)2 were used as alkali activators to prepare alkali-activated solidification materials for oilfield road base applications. The optimal curing system identified in this study (4 wt.% NaOH + 20 wt.% furnace ash) falls within the commonly reported dosage ranges for alkali-activated solid-waste materials, where NaOH contents are typically 3%–8% and furnace ash contents 15%–30%. Considering the distinct chemical characteristics of the Xinjiang oilfield solid wastes, a targeted optimization strategy was adopted to achieve a balance between mechanical performance and economic feasibility. Based on mix-proportion experiments, macroscopic mechanical properties were evaluated. In combination with X-ray diffraction (XRD), laser particle size analysis, simultaneous thermal analysis (TG–DSC), and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM–EDS), the influence of activator type on both mechanical performance and microstructural evolution was systematically investigated. The results indicate that the system containing 4 wt.% NaOH + 20 wt.% furnace ash exhibits the best overall performance, achieving a 28-day compressive strength of 4.81 MPa and a splitting tensile strength of 0.41 MPa, which are significantly higher than those of the Na2O·nSiO2 system (3 wt.% Na2O·nSiO2 + 20 wt.% furnace ash) and the Ca(OH)2 system (4 wt.% Ca(OH)2 + 15 wt.% furnace ash). The primary hydration products were identified as C-(N)-A-S-H and C-S-H gels. The type of alkali activator plays a decisive role in regulating hydration reaction kinetics and the spatial distribution of Ca and Si elements, thereby governing the hierarchical differences in macroscopic mechanical properties. In particular, NaOH generates a highly alkaline environment that promotes the dissolution of active Si/Al components in both drilling cuttings and furnace ash, enhances gel polymerization, and results in a denser microstructure. This study provides theoretical and technical support for the high-value utilization of oilfield solid wastes in highway base engineering.

ABSTRACT This study conducted a theoretical analysis on the hydrodynamic factors of surface cleaning and then carried out detection on the surface physicochemical properties of coarse/fine coal particles after surface cleaning. Results show that the desorption degree of fine slimes does not increase monotonically with the impeller speed. Within the range of conventional high-intensity conditioning rotation speeds, a medium impeller speed of 1600–1900 rpm was the appropriate speed for surface cleaning. The cleaning effect depended on the impeller speed rather than the cleaning time. Surface cleaning increased the contact angle, single-bubble loading capacity, and induction time by 18.67%, 65.96%, and 28.99%, respectively. XPS analysis results indicated that when the cleaning impeller speed was 1600 rpm, the content of C-C/C-H on the surface of +75 μm coal samples increased by 4.10%, while the content of hydrophilic groups such as C-O-C/C-OH decreased by 15.23%. SEM-EDS analysis results showed that, after surface cleaning, the content of C element on the surface of coarse coal and fine coal increased by 34.48% and 25.51%, respectively; the contents of O, Al, and Si elements in coarse coal decreased by 57.16%, 88.79%, and 83.85%, respectively, while those in fine coal decreased by 32.22%, 62.79%, and 55.42%, respectively.

Finding new sources of high purity silica is becoming increasingly important for solar panel manufacturing. Behind quartz, sandstone can be one of the most important sources of silica for advanced technological applications. Despite its abundance in the Earth’s crust, the widespread use of sandstone is limited by the presence of undesirable oxide. This is the case for the studied sandstone rocks, where impurities, particularly iron and aluminum oxide, restrict the suitability of this silica for producing advanced materials. This work presents an optimized multistage purification protocol specifically engineered for quartzose sandstone. We systematically characterize quartzose sandstone from northern Algeria, an abundant yet underexploited sedimentary resource, demonstrating an initial rich silica content but with problematic levels of Fe 2 O 3 and Al 2 O 3 impurities. The core scientific contribution is the establishment of a tailored sequence: granulometric sieving to isolate the optimal 250–400 µm fraction (89.15% SiO 2 ), dry high intensity magnetic separation, and optimized acid leaching using 4 M HCl at 90 °C for 2 h that show leaching efficiency plateaus. Mechanical analysis reveals the 250–400 µm fractions as a liberation sweet spot where quartz grains are maximally freed from the detrital matrix. The results are encouraging, demonstrating that the applied process successfully increased the silica content from an average of 89.15%–99.28%. Furthermore, it significantly reduced the impurity levels, lowering the iron oxide content from 0.27% to 0.02% and the alumina content from 2.46% to 0.02%. By demonstrating the viability of sandstone as a photovoltaic grade feedstock precursor for metallurgical grade silicon (MG-Si) production, which is the essential first step in manufacturing solar grade silicon (SoG-Si) for photovoltaics., this work provides a scalable pathway for diversifying the solar industry’s silica supply chain.