Search Results (36)

The simulation analysis of a novel stay-in-place formwork (SIPF) beam reinforced with perforated steel pipe skeleton was conducted. The SIPF beam consists of a modified magnesium oxysulfide mortar (MMOM) formwork, a square steel pipe skeleton with holes dug on the sides and top, and cast-in-place concrete. The finite element (FE) analysis model of the SIPF beam was established by using the ABAQUS CAE 2021 software, and simulation analysis was conducted with the shear span ratio (SSR), the distance between the remaining steel strips, and the strength of concrete as the variation parameters. The results show that the stiffness and shear capacity of the SIPF beam decrease with the increase in SSR and increase with the decrease in strip spacing. Under the same conditions, when the concrete strength grade is increased from C30 to C50, the shear bearing capacity of the SIPF beam increases by 11.8% to 16.2%. When the spacing of the steel strips is reduced from 200 mm to 150 mm, the shear bearing capacity can be increased by 12.7% to 31.5%. When the SSR increases from 1.5 to 3.0, the shear bearing capacity decreases by 26.9% to 37.3%. Moreover, with the increase in the SSR, the influence of the steel strip spacing on the shear bearing capacity of the SIPF beam improves, while the influence of the concrete strength on the shear bearing capacity decreases. Taking parameters such as SSR, steel strip spacing, and concrete strength as variables, the influence of steel pipe constraining the core concrete on the shear bearing capacity was considered. The calculation formula for the shear bearing capacity of the SIPF beam with perforated steel pipe skeleton was established. The calculation results fit well with the laboratory test and simulation test results and can be used for the design and calculation of engineering structures. Full article

Organic acids could act as retarders in magnesium oxysulfide (MOS) systems, not only delaying setting and improving fluidity but also enhancing compressive strength and water resistance. These effects are generally attributed to both the presence of H⁺ ions and anion chelation. However, the enhancement efficiency of different organic acids in MOS systems varies significantly due to differences in their molecular structures. To determine the underlying mechanism, this study comparatively investigated the effects of amino trimethylene phosphonic acid (ATMP) and tartaric acid (TA) on the setting time, fluidity, compressive strength, and water resistance of the MOS system, with the two additives incorporated at mole ratios to MgO ranging from 0.002 to 0.006. The mechanism behind it was revealed by discussion on the hydration heat, hydrates, and pH value. Results showed that both ATMP and TA could effectively improve the fluidity, delay the setting process, and enhance the mechanical properties, including strength and water resistance. At a mole ratio of 0.006, the incorporation of ATMP increased the 28 d compressive strength and the softening coefficient by 214.12% and 37.29%, respectively, compared with the blank group. In contrast, under the same dosage, TA led to an increase of 55.13% in the 28 d strength and 22.03% in the softening coefficient. Furthermore, hydration heat, product analysis, and pH measurements indicated that both ATMP and TA inhibited hydration during the initial hours but promoted hydration at later stages. The potential reason could be divided into two aspects: (1) H⁺ ions from ATMP and TA suppressing the formation of Mg(OH)₂; (2) anion chelation with Mg²⁺ in the liquid phase, leading to a supersaturated solution with higher saturation, which further hindered Mg(OH)₂ formation and facilitated the later development of 5Mg(OH)₂·MgSO₄·7H₂O (517 phase). By contrast, under the same mole dosage of H⁺ or anions, the enhancement in compressive strength as well as the water resistance is superior when using ATMP. This was owing to its stronger chelating ability of ATMP, which more effectively inhibited Mg(OH)₂ formation and then promoted the formation of the 517 phase. These findings confirm that the chelating ability of anions exerts an important impact on the retarding effect as well as the enhancement of strength in MOS systems. Full article

S355NL structural steel is extensively employed in bridges, ships, and power station equipment owing to its excellent tensile strength, weldability, and low-temperature toughness. However, pronounced fluctuations in its Charpy impact energy at low temperatures significantly compromise the reliability and service life of critical components. In this study, vacuum-induction-melted ingots of S355NL steel containing 0–0.086 wt.% rare earth cerium were prepared. The effects of Ce on microstructures, inclusions, and impact toughness were systematically investigated using optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and Charpy V-notch testing. The results indicate that appropriate Ce additions (0.0011–0.0049 wt.%) refine the average grain size from 5.27 μm to 4.88 μm, reduce the pearlite interlamellar spacing from 204 nm to 169 nm, and promote the transformation of large-size Al₂O₃-MnS composite inclusions into fine, spherical, Ce-rich oxysulfides. Charpy V-notch tests at –50 °C reveal that 0.0011 wt.% Ce enhances both longitudinal (269.7 J) and transverse (257.4 J) absorbed energies while minimizing anisotropy (E_t/E_l  =  1.01). Conversely, excessive Ce addition (0.086 wt.%) leads to coarse inclusions and deteriorates impact performance. These findings establish an optimal Ce window (0.0011–0.0049 wt.%) for microstructural and inclusion engineering to enhance the low-temperature impact toughness of S355NL steel. Full article

This study investigates the influence of rare earth elements Ce and Y on the evolution of inclusions in T91 steel by melting experimental steels with varying Ce-Y contents in a vacuum induction melting furnace. The results show that the inclusions in the steel without rare earth are mainly composed of Mg-Al-O oxides, (Nb, V, Ti)(C, N) carbonitrides, and composite inclusions formed by carbonitrides coated oxides, and all of them have obvious edges and corners. Upon the addition of different concentrations of Ce and Y, the oxygen content in the steel significantly decreased, and the inclusions were modified into spherical rare earth oxides, sulfides, and oxy-sulfides. Additionally, no large-sized primary carbonitrides were observed. The average size of the inclusions was reduced from 2.8 μm in the non-rare-earth-added steel to 1.7 μm and 1.9 μm with rare earth addition. Thermodynamic analysis indicates that the possible inclusions precipitated in the steel with varying Ce contents include Ce₂O₃, Ce₂O₂S, Y₂O₃, Y₂S₃, and CeS. With the increase in Ce content, the rare earth inclusions Y₂S₃, Y₂O_3, and CeS can be transformed into Ce₂O₂S and Ce₂O₃. There are two kinds of reactions in the process of high-temperature homogenization: one is the internal transformation reaction of inclusions, which makes Y easier to aggregate in the inner layer, and the other is the reaction of Y₂S₃→CeS and Y₂O₃ + Y₂S₃→Ce₂O₂S due to the diffusion of Ce in the matrix to the inclusions. Combined with the mismatch analysis, it can be seen that Al₂O₃ has the best effect on the heterogeneous nucleation of carbonitrides during the solidification of molten steel. Among the rare earth inclusions, only Ce₂O₃ may become the nucleation core of carbonitrides, and the rest are more difficult to form heterogeneous nucleation. Therefore, by Ce-Y composite addition, increasing the Y/Ce ratio can reduce the formation of Ce₂O₃, which can avoid the precipitation of primary carbonitride and ultimately improve the dispersion strengthening effect. This study is of great significance for understanding the mechanism of rare earth elements in steel and provides theoretical guidance for the composition design and industrial trial production of rare earth steel. Full article

Rare-earth oxysulfides are a class of functional ceramic materials with excellent physico-chemical properties and rich functionality. In this study, La₂O₂S powders were prepared from La₂S₃ and La₂O₃ powders at 1000 °C by pressureless sintering. La₂O₂S compacts were synthesized from La₂S₃ and La₂O₃ powders at 800–1600 °C by spark plasma sintering. The influences of sintering temperature and time on the preparation of La₂O₂S were studied. XRD results indicated that La₂O₂S ceramics were synthesized successfully and that the lattice constants of La₂O₂S were close to the theoretical values. SEM showed that the microstructure of La₂O₂S compacts was homogeneous. The specific heat of La₂O₂S mainly came from lattice contribution, and its Debye temperature was 237 K. The UV–visible absorption spectra showed different absorption levels in the 240–300 nm range. Raman spectroscopy revealed distinct peaks at different temperatures, indicating changes in the covalence band. The relative density of La₂O₂S ceramics was 92% and lower than theoretical values. Hardness of the synthesized La₂O₂S was greater than that of Gd₂O₂S ceramics. Full article

Kermesite (Sb₂S₂O), a needle-like unstable secondary oxysulfide, has made visible advancements in optimizing its triclinic crystal system through twinning discovery. However, research on twinning behavior at micro and nano scales, including its growth mechanisms and impact on kermesite morphologies, remains notably scarce. Our study focuses on kermesite crystal clusters from a private collection in Yunnan, China, confirming the chemical formula as Sb₂S_1.97O_1.03 through EPMA. Single-crystal XRD yielded refined unit cell parameters (a = 8.153(5) Å, b = 10.717(7) Å, c = 5.796(3) Å; α = 102.836(10)°, β = 110.556(8)°, γ = 100.999(12)°), revealing space group P$\overline{1}$ with Z = 4 and indicating twinning with a ratio of 27.4%. Remarkably, a Transmission Electron Microscope (TEM) provided the first direct observation of twinning in natural kermesite, revealing rotational twins with varying widths and lengths (ranging from 100 nm to several millimeters). Analysis and simulation elucidated that rotational twins, generated by a 180° rotation, align with the mineral’s elongation direction along the [Sb₂S₂O₄]_n chains (a-axis), challenging the conventional long-axis direction (b-axis) for crystal growth. This study proposes a symbiotic relationship between kermesite growth and twinning, suggesting that the observed X-shaped growth in crystal clusters results from the collaboration of single crystals (growing along b) and twins (growing along a) in the unit cell. These findings contribute to our understanding of kermesite’s structural complexities and the potential growth and formation mechanism of crystal clusters. Full article

A laboratory study was carried out to better understand the factors that contribute to the formation of complex inclusions, as inclusions play an important role during steel production; if not properly managed, inclusions can cause nozzle clogging during continuous casting and also damage the steel’s mechanical properties and machineability. To determine the chemical composition of inclusions that are less detrimental to the machineability of Al-deoxidized and Ca-treated gear steels, thermodynamic calculations and automated scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), as well as electron probe micro-X-ray analysis (EPMA) with the wavelength dispersive spectroscopy (WDS) technique, were utilized. The findings demonstrated that the morphology of inclusions changed from irregular to a more spherical type and the composition also changed to dual oxy-sulfides from pure oxides and sulfides as the Ca concentration in the steel was increased up to 36 ppm. The amount of Pure MnS sulfides also reduced significantly after Ca treatment. The ternary phase diagram and stability diagram for the inclusions revealed that 15–25 ppm Ca is the optimal range for the modification of both oxides and sulfides into the desired morphology and composition under the stipulation that the concentration of O in the steel is maintained at or below 50 ppm. Full article

The localized corrosion behavior of stainless steel (SS) induced by typical inclusion such as MnS and oxy-sulfide in NaCl solution was investigated by immersion tests and microelectrochemical tests. Oxy-sulfide consists of an internal polygonal oxide part and an external sulfide part. The surface Volta potential of the sulfide part is always lower than that of the surrounding matrix, as in the case of individual MnS, while the potential of the oxide part is indistinguishable from that of the surrounding matrix. Sulfides are soluble, while oxides are almost insoluble. Oxy-sulfide exhibits a complex electrochemical behavior in the passive region, which can be attributed to its complex composition and multi-interface coupling effects. It was found that both MnS and oxy-sulfide increase the susceptibility of the local area to pitting corrosion. Full article

In this paper, the effect of rare earth Ce content on the morphology, composition, type and size distribution of inclusions in W350 non-oriented silicon steel was investigated by means of ICP-MS (inductively coupled plasma mass spectrometry), SEM/EDS (scanning electron microscope-energy Dispersive Spectrometer), and ASPEX (automated SEM/EDS inclusion analysis). The results showed that with the increase of Ce content in the steel, the modification sequence of inclusions was CeAlO₃→Ce₂O₂S→Ce_xS_y. The type and size distribution of inclusions in the steel obviously changed with the difference in added Ce content. When the added Ce content in the steel was 10 ppm, 14 ppm, 20 ppm and 30 ppm respectively, the rare earth inclusions were mainly CeAlO₃-Ce₂O₂S. Furthermore, when the added Ce content increased to 60 ppm, the rare earth inclusions were mainly Ce₂O₂S with a small amount of CeAlO₃ contained in part inclusions. When the added Ce content increased continually to 95 ppm, the rare earth inclusions were mainly Ce_xS_y-Ce₂O₂S. The critical Ce content for the conversion between CeAlO₃ and Ce₂O₂S was 41 ppm. To ensure that inclusions transform from CeAlO₃ to Ce₂O₂S, the Ce content in the steel should be greater than 41 ppm. Under the current experimental conditions, it was found that when the Ce content was 20 ppm, the number density and proportion of inclusions in the steel were lower, and their average size was larger. When the added Ce content increased to 95 ppm, the number density of inclusions in the steel significantly increased, which deteriorated the steel cleanliness. Full article

The structural properties of phosphor materials, such as their grain size distribution (GSD), affect their overall optical emission performance. In the widely used gadolinium oxysulfide (Gd₂O₂S) host material, the type of activator is one significant parameter that also changes the GSD of the powder phosphor. For this reason, in this study, different phosphors samples of Gd₂O₂S:Tb, Gd₂O₂S:Eu, and Gd₂O₂S:Pr,Ce,F, were analyzed, their GSDs were experimentally determined using the scanning electron microscopy (SEM) technique, and thereafter, their optical emission profiles were investigated using the LIGHTAWE Monte Carlo simulation package. Two sets of GSDs were examined corresponding to approximately equal mean particle size, such as: (i) 1.232 μm, 1.769 μm and 1.784 μm, and (ii) 2.377 μm, 3.644 μm and 3.677 μm, for Tb, Eu and Pr,Ce,F, respectively. The results showed that light absorption was almost similar, for instance, 25.45% and 8.17% for both cases of Eu dopant utilizing a thin layer (100 μm), however, given a thicker layer (200 μm), the difference was more obvious, 22.82%. On the other hand, a high amount of light loss within the phosphor affects the laterally directed light quanta, which lead to sharper distributions and therefore to higher resolution properties of the samples. Full article

The effect of lanthanum addition on the formation behaviors of inclusions in Q355B weathering steel was investigated by laboratory experiments and thermodynamic calculations. The results demonstrate that the main inclusions in weathering steel without La addition are large-sized irregular Al₂O₃ and MnS, with an average size of about 5.35 μm. As La content increases from 0.0075 to 0.0184 wt.%, the dominant inclusions transform from MnS, LaAlO₃, and Al₂O₃-LaAlO₃ into MnS, La₂O₃, and LaAlO₃-La₂O₃. Meanwhile, the average size of inclusions significantly decreases from 3.4 to 2.48 μm and the distribution is more dispersive. When the La content increases to 0.0425 wt.%, the original MnS and Al₂O₃ inclusions are completely modified into La₂O₂S and La₂O₃ but the inclusions demonstrate serious agglomeration and growth. The thermodynamic calculations indicate that Al₂O₃ and various lanthanum-containing inclusions are formed in the liquid phase. As the La content in molten steel increases from 0 to 0.0425 wt.%, the Al₂O₃ inclusion is inclined to be modified into lanthanum oxide and lanthanum oxysulfide and the modification process is Al₂O₃ → LaAlO₃ → La₂O₃ → La₂O₂S, which is very consistent with the experimental observations. Full article

Two-dimensional (2D) or ultrathin metal sulfides have been emerging candidates in developing high-performance gas sensors given their physisorption-dominated interaction with target gas molecules. Their oxysulfide derivatives, as intermediates between oxides and sulfides, were recently demonstrated to have fully reversible responses at room temperature and long-term device stability. In this work, we explored the micro-scale self-assembly of ultrathin nickel oxysulfide through the calcination of nickel sulfide in a controllable air environment. The thermal treatment resulted in the replacement of most S atoms in the Ni-S frameworks by O atoms, leading to the crystal phase transition from original hexagonal to orthorhombic coordination. In addition, the corresponding bandgap was slightly expanded by ~0.15 eV compared to that of pure nickel sulfide. Nickel oxysulfide exhibited a fully reversible response towards H₂ at room temperature for concentrations ranging from 0.25% and 1%, without the implementation of external stimuli such as light excitation and voltage biasing. The maximum response factor of ~3.24% was obtained at 1% H₂, which is at least one order larger than those of common industrial gases including CH₄, CO₂, and NO₂. Such an impressive response was also highly stable for at least four consecutive cycles. This work further demonstrates the great potential of metal oxysulfides in room-temperature gas sensing. Full article

Bulk-heterojunction (BHJ) polymer solar cells have received a great deal of attention mainly due to the possibility of higher power conversion efficiency for photovoltaic applications. Therefore, in this study, relatively novel polymer BHJ solar cells are proposed (ITO/ETL/PTB7:PC₇₀BM/PEDOT:PSS/Au) with various electron transport layers (ETL) such as zinc oxysulfide (Zn(O,S)), zinc selenide (ZnSe), and poly[(9,9-bis(3′-((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] dibromide (PFN-Br). Here, each ETL material is selected based on the energy bandgap compatibility with ITO as well as the PTB7:PC₇₀BM active layer and is based on other physical properties, which are generally required for efficient photovoltaic responses. Each proposed device is comprehensively optimized and then photovoltaic responses are simulated and compared using the software SCAPS-1D. It was observed that the ITO/Zn(O,S)/PTB7:PC70BM/PEDOT:PSS/Au device offered the highest power-conversion efficiency of up to 17.15% with an open-circuit voltage of 0.85 volts, a short-circuit current of 28.23 mA/cm², and a fill factor of 70.69%. Full article

The primary purpose of recent research has been to achieve a higher power conversion efficiency (PCE) with stable characteristics, either through experimental studies or through modeling and simulation. In this study, a theoretical analysis of an efficient perovskite solar cell (PSC) with cuprous oxide (Cu₂O) as the hole transport material (HTM) and zinc oxysulfide (ZnOS) as the electron transport material (ETM) was proposed to replace the traditional HTMs or ETMs. In addition, the impact of doping the perovskite layer was investigated. The results show that the heterostructure of n-p PSC without an electron transport layer (ETL) could replace the traditional n-i-p structure with better performance metrics and more stability due to reducing the number of layers and interfaces. The impact of HTM doping and thickness was investigated. In addition, the influence of the energy gap of the absorber layer was studied. Furthermore, the proposed PSC without ETL was used as a top sub-cell with germanium-telluride (GeTe) as a bottom sub-cell to produce an efficient tandem cell and boost the PCE. An ETL-free PSC/GeTe tandem cell is proposed for the first time to provide an efficient and stable tandem solar cell with a PCE of 45.99%. Finally, a comparison between the performance metrics of the proposed tandem solar cell and those of other recent studies is provided. All the simulations performed in this study are accomplished by using SCAPS-1D. Full article

Radiodiagnostic technologies are powerful tools for preventing diseases and monitoring the condition of patients. Medicine and sectors such as industry and research all use this inspection methodology. This field demands innovative and more sophisticated systems and materials for improving resolution and sensitivity, leading to a faster, reliable, and safe diagnosis. In this study, a large characterization of gadolinium oxysulfide (Gd₂O₂S) scintillator screens for imaging applications has been carried out. Seven scintillator samples were doped with praseodymium (Pr³⁺), terbium (Tb³⁺) activators and co-doped with praseodymium, cerium, and fluorine (Gd₂O₂S:Pr,Ce,F). The sample screens were prepared in the laboratory in the form of high packing density screens, following the methodology used in screen sample preparation in infrared spectroscopy and luminescence. Parameters such as quantum detection efficiency (QDE), energy absorption efficiency (EAE), and absolute luminescence efficiency (ALE) were evaluated. In parallel, a structural characterization was performed, via XRD and SEM analysis, for quality control purposes as well as for correlation with optical properties. Spatial resolution properties were experimentally evaluated via the Modulation Transfer Function. Results were compared with published data about Gd₂O₂S:Pr,Ce,F screens produced with a standard method of a sedimentation technique. In particular, the ALE rose with the X-ray tube voltage up to 100 kVp, while among the different dopants, Gd₂O₂S:Pr exhibited the highest ALE value. When comparing screens with different thicknesses, a linear trend for the ALE value was not observed; the highest ALE value was measured for the 0.57 mm thick Gd₂O₂S:Pr,Ce,F sample, while the best MTF values were found in the thinner Gd₂O₂S:Pr,Ce,F screen with 0.38 mm thickness. Full article