The concluding phase of our investigation involved modeling an industrial forging process to ascertain the foundational assumptions underlying this newly developed precision forging method, leveraging a hydraulic press, alongside the preparation of tools for the re-forging of a needle rail from 350HT steel (60E1A6 profile) to the 60E1 profile used in railroad switch points.
The fabrication of clad Cu/Al composites benefits from the promising rotary swaging process. An analysis of residual stresses, originating from the processing of a particular arrangement of Al filaments within a Cu matrix, particularly the influence of bar reversals between processing steps, was performed. The study employed two methods: (i) neutron diffraction, utilizing a novel method for pseudo-strain correction, and (ii) finite element simulation. A preliminary study of stress differences in the Cu phase suggested that hydrostatic stresses are localized around the central Al filament when the specimen is reversed during the scan procedures. Consequently, the analysis of the hydrostatic and deviatoric components became possible following the calculation of the stress-free reference, a result of this fact. The von Mises stress relation was employed to calculate the stresses, finally. For both the reversed and non-reversed specimens, the axial deviatoric stresses and hydrostatic stresses (distant from the filaments) are either zero or compressive. A shift in the bar's direction slightly impacts the overall state within the high-density Al filament region, normally under tensile hydrostatic stresses, but this reversal appears beneficial in avoiding plastification in zones lacking aluminum wires. The finite element analysis demonstrated the presence of shear stresses; however, the von Mises relation produced comparable trends between the simulation and neutron measurements. The radial neutron diffraction peak's considerable width may be explained by the presence of microstresses during the measurement.
Membrane technologies and material science play a vital role in the separation of hydrogen from natural gas, as the transition to a hydrogen economy is underway. Employing the pre-existing natural gas network for hydrogen transport may yield lower costs when compared to the construction of a new hydrogen pipeline system. Current research actively seeks to develop novel structured materials for gas separation, emphasizing the addition of varied additive types to polymeric substances. zebrafish-based bioassays Numerous gaseous combinations have been scrutinized, revealing the mechanisms by which gases permeate those membranes. Unfortunately, separating pure hydrogen from hydrogen/methane mixtures still presents a considerable challenge, needing major improvements to encourage the transition to more sustainable energy sources. In the realm of membrane materials, fluoro-based polymers, including PVDF-HFP and NafionTM, are particularly popular due to their remarkable properties, while further optimization efforts are in progress in this context. Large graphite substrates received depositions of thin hybrid polymer-based membrane films in this study. Evaluation of hydrogen/methane gas mixture separation capabilities was conducted on 200-meter-thick graphite foils, incorporating diverse weight ratios of PVDF-HFP and NafionTM polymers. Small punch tests were performed to study the membrane's mechanical response, replicating the test conditions for a precise analysis. Lastly, the gas separation activity and permeability of hydrogen and methane through membranes were evaluated at room temperature (25°C) and a pressure difference of approximately 15 bar under near-atmospheric conditions. Using a 41:1 weight ratio of PVDF-HFP to NafionTM polymer resulted in the highest membrane performance. Starting with the 11 hydrogen/methane gas blend, a measurement of 326% (by volume) hydrogen enrichment was performed. Moreover, the experimental and theoretical selectivity values exhibited a strong concordance.
The established rebar steel rolling process necessitates a review and redesign, focusing on increasing productivity and decreasing energy expenditure during the slitting rolling procedure. This research thoroughly investigates and modifies slitting passes to attain superior rolling stability and reduce power consumption. Egyptian rebar steel, grade B400B-R, has been the subject of the study, a grade equivalent to ASTM A615M, Grade 40 steel. To produce a single, barreled strip, the rolled strip is edged using grooved rolls in the initial stages, before the slitting pass. The pressing action in the next slitting stand becomes unstable because of the single-barrel form, specifically due to the influence of the slitting roll knife. To achieve the deformation of the edging stand, multiple industrial trials are conducted using a grooveless roll. check details Following this process, a double-barreled slab is the outcome. Finite element simulations of the edging pass, employing both grooved and grooveless rolls, are conducted in parallel, alongside simulations of slabs with single and double barreled forms, and similar geometries. Furthermore, finite element simulations of the slitting stand, employing idealized single-barreled strips, are carried out. The single barreled strip's power, measured experimentally at (216 kW) in the industrial process, is favorably consistent with the (245 kW) calculated via FE simulations. The FE model's precision regarding its material model and boundary conditions is substantiated by this result. A broader FE model now encompasses the slit rolling stand, designed for double-barreled strip processing, which was formerly reliant on grooveless edging rolls. Analysis reveals a 12% reduction in power consumption, dropping from 185 kW to 165 kW, when slitting a single-barreled strip.
For the purpose of strengthening the mechanical characteristics of porous hierarchical carbon, cellulosic fiber fabric was combined with resorcinol/formaldehyde (RF) precursor resins. The inert atmosphere facilitated the carbonization of the composites, which was monitored by TGA/MS. Evaluation of mechanical properties via nanoindentation showcases a boost in elastic modulus, attributed to the reinforcing action of the carbonized fiber fabric. During the drying process, the adsorption of the RF resin precursor onto the fabric was found to stabilize its porosity (including micro and mesopores) and incorporate macropores. The analysis of N2 adsorption isotherms determines textural properties, specifically a BET surface area of 558 square meters per gram. The electrochemical properties of the porous carbon are characterized using cyclic voltammetry (CV), chronocoulometry (CC), and electrochemical impedance spectroscopy (EIS). The specific capacitances (in 1 M sulfuric acid) using different measurement techniques (CV and EIS) reached 182 Fg⁻¹ and 160 Fg⁻¹ respectively. Employing the Probe Bean Deflection approach, the potential-driven ion exchange was evaluated. Oxidation of hydroquinone moieties on carbon surfaces leads to the expulsion of protons and other ions, as observed. In neutral media, when the potential is changed from negative values to positive values, relative to the zero-charge potential, the consequent effect is the release of cations and the subsequent insertion of anions.
The quality and performance of MgO-based products are significantly impacted by the hydration reaction. A concluding analysis revealed the surface hydration of MgO as the root cause of the issue. Insight into the fundamental causes of the issue can be gained through investigation of water adsorption and reaction phenomena on MgO surfaces. Employing first-principles calculations, this paper examines the influence of various water molecule orientations, sites, and surface coverages on the adsorption behavior of water molecules on the MgO (100) crystal plane. The experimental outcomes highlight that the placement and orientation of a single water molecule have no effect on the adsorption energy or the configuration of the adsorbed layer. Instability characterizes the monomolecular water adsorption process, accompanied by almost no charge transfer. This signifies physical adsorption, indicating that water molecule dissociation will not occur upon monomolecular water adsorption onto the MgO (100) plane. Exceeding a coverage of one water molecule triggers dissociation, resulting in an elevated population count between magnesium and osmium-hydrogen atoms, subsequently forming an ionic bond. Significant alterations in the density of O p orbital states are closely correlated with surface dissociation and stabilization.
The fine particle nature and UV-shielding properties of zinc oxide (ZnO) make it a widely used inorganic sunscreen material. Yet, nano-sized powders might induce toxic responses and adverse health complications. The progress in creating particles that are not nano-sized has been gradual. In this work, synthesis strategies for non-nano-sized zinc oxide particles for ultraviolet protection were examined. Variations in the starting material, KOH concentration, and input rate allow the production of ZnO particles with diverse morphologies, such as needle-shaped, planar, and vertically-walled forms. virus genetic variation To fabricate cosmetic samples, various ratios of synthesized powders were combined. The physical properties and effectiveness of UV blockage of various samples were investigated by utilizing scanning electron microscopy (SEM), X-ray diffraction (XRD), a particle size analyzer (PSA), and an ultraviolet-visible (UV-Vis) spectrophotometer. Samples containing an 11:1 ratio of needle-type zinc oxide and vertical-walled zinc oxide exhibited enhanced light-blocking properties because of improved dispersion and the prevention of particle clumping. The 11 mixed samples passed muster under the European nanomaterials regulation because nano-sized particles were not found in the mix. The 11 mixed powder, boasting superior UV protection across UVA and UVB spectrums, displayed promise as a key component in UV-protective cosmetics.
Despite the impressive growth of additively manufactured titanium alloys in aerospace, the persistence of porosity, significant surface roughness, and problematic tensile residual stresses hinder their transition into other sectors like maritime.