Energy Dispersive X-ray Spectroscopy Analysis Research Articles

Enhanced susceptibility of high-strength fastener nuts to hydrogen-induced stress corrosion cracking

Abstract High-strength HV-fastener sets of dimensions M48 and M64 with property class 10.9 were employed in offshore wind turbine frameworks. The M64 were used in coupling flanges within monopiles. The M48 were employed in another offshore wind farm and encountered natural weathering. In both installations, time-delayed fractures of the nuts were observed. Owing to the presence of macroscopically visible corrosion products, hydrogen-induced stress corrosion cracking (Hi-SCC) was established as the probable cause of failure. However, a nut fracture in a properly pre-tensioned bolt assembly is atypical since the stresses in the bolt threads are higher than those in the nuts. Based on the Hi-SCC theory, the fracture should occur at the most stressed component, which is the bolt. During the root cause analysis, extensive examinations were conducted to determine the cause of the nut fractures. The focus was on investigating whether the nut material was more prone to Hi-SCC than the bolt material. The examination program included scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM-EDS) analysis of the fracture surfaces, optical microscopy of microspecimens, mechanical tests, and stress rupture tests of hydrogen-charged specimens. While the results suggest that the tested nuts comply with the requirements of the applicable standards regarding material properties, they also reveal that the nut material is, despite its lower tensile strength, significantly more susceptible to Hi-SCC than the bolt material. Therefore, a direct relationship between material susceptibility to Hi-SCC and the tensile strength, as standards and guidelines imply, is not given.

Residual stress and subsurface damage in sapphire ultra-precision grinding

This study conducted experiments on ultra-precision grinding of sapphire using various strategies. It evaluated surface and subsurface characteristics across multiple dimensions, including morphology, scale, mechanical properties, residual stresses, lattice distortions, in-service properties, and chemical components. The research aimed to explore the intrinsic relationship between these behaviours. The findings revealed that both semi-finish grinding and ultra-precision grinding achieved ductile and low-roughness surfaces, with surface hardness enhancement near the grinding surface. Additionally, Raman spectra wave shifts were able to distinguish residual stresses at different grinding strategies, with larger stresses observed in ultra-precision grinding compared to semi-finish grinding and rough grinding. Furthermore, dense etching dislocation pits were observed on the ultra-precision grinding surface, responding to the scale of residual stress. The presence of larger subsurface cracks in semi-finish grinding and rough grinding was found to contribute to the release of residual stress. Moreover, ultra-precision grinding significantly reduced subsurface damage compared to rough grinding, with a reduction from 23.8 μm to 4.3 μm. Photothermal absorption during rough grinding was noted to be over 10 times higher than in ultra-precision grinding. Transmission electron microscopy (TEM) analysis revealed that subsurface damage included microcrack-induced line defects and uniform plastic deformation areas. This damage involved lattice aberrations, dislocations, stacking faults, and thin amorphous layers. The hardness and modulus of the subsurface damage layer were observed to decrease. Additionally, Raman spectra wave shifts were able to distinguish the subsurface damage layer in ultra-precision grinding. Energy-dispersive X-ray spectroscopy (EDS) analysis showed no change in the chemical components of the subsurface damage layer. Furthermore, a model was proposed to evaluate subsurface damage based on residual stress, and the mechanism of residual stress inducing damage in ultra-precision grinding was further analysed.

New Insights in Metallurgical Manufacturing in the Caucasian Area: The Case Study of Artefacts from the Samshvilde Citadel Ruins (South Georgia)

An archaeometric approach was applied to the study of the hoard found in the Samshvilde fortress, one of the richest areas of archaeological artefacts in Caucasian Georgia, since it is representative of the historical events from the Neolithic period until the most recent epochs. In this context, four coins dated back to the 12th–13th centuries AD to the reign of King Giorgi III, Queen Tamar, and King Giorgi IV of Georgia underwent different analytical methods to collect information about the technological production process, the probable forge location, and their conservation state. Optical microscope observations provided details about the decorations, the stylistic aspects, and a preliminary evaluation of the conservation state. Portable X-ray fluorescence and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis revealed a composition consisting almost exclusively of copper with a lower amount of tin, lead, and silver. Moreover, degradation products (copper chlorides and sulphates) and cuprite patina were identified. The metal-supplying areas could be related to the nearby Bolnisi Mining District, and the forge location could coincide with the hoard location in Samshvilde, but further data and analyses are necessary.

The Synthesis of FeS and Investigation on Electrochemical Sensing Toward Neuroprotector.

Background Electrochemical sensing is a versatile field that uses electrochemistry concepts to detect and measure various substances. It finds applications in clinical diagnostics and environmental monitoring. Scientists are currently working on creating reliable electrochemical sensing devices that can accurately detect ascorbic acid. Iron sulfide (FeS) has emerged as a promising material for these sensors due to its excellent electrical conductivity, catalytic activity, and stability. Materials and methods The FeS nanoparticles were synthesized through the hydrothermal method of synthesis. The glassy carbon electrode (GCE) with a surface area of 0.071 cm2was modified with FeS before the working electrode was mechanically polished with 1 µm, 0.3 µm, and 0.05 µm alumina pastes for mirror finishing. Then it was subjected to ultrasonication in double distilled water for a few minutes to clean the surface of GCE. The FeS suspension was prepared by dispersing 5 mg of FeS in 10 mL of ethanol during 20 minutes of ultrasonic agitation then the GCE was coated with 10 μL of the suspension by drop coating method and dried in air. Results In this study, FeS nanoparticles were synthesized by the hydrothermal method of synthesis, and it was tested for their electrochemical sensing properties by various tests. Based on the field emission-scanning electron microscope(FE-SEM) analysis, scan rate effect test, cyclic voltammetric test, X-ray diffraction (XRD), and energy-dispersive X-ray(EDX) spectroscopy analysis done and results obtained, it was seen that the synthesized FeS nanoparticles are highly pure and have a crystalline structure. FeS has an even morphology. The synthesized particles also showed highly sensitive and specific sensing towardascorbic acid when compared to unmodified 10.1 µAelectrodes with a sensing value of 12.51μA, thereby fulfilling the aim of this study. Conclusion Based on the outcomes of the diverse tests carried out, it is evident that the sample displayed a high crystalline nature as indicated by the XRD test. Additionally, the sample exhibited a uniform morphology, exceptional stability, and remarkable sensitivity. The developed FeS-based electrochemical sensor was found to be exceptionally pure and showed excellent performance, showcasing both high sensitivity and selectivity towardascorbic acid.

Thiourea modulated supercapacitive behavior of reduced graphene oxide

In this report, we investigated the role of the concentration of nitrogen and sulfur containing thiourea in modulating the electrochemical properties of reduced Graphene Oxide (rGO) by controlling the percentage of heteroatoms on the rGO surface. The synthesis route involved the preparation of Graphene Oxide (GO) using an improved method of synthesis in an economical way by reducing the volume of concentrated acids used. Furthermore, GO is reduced by using different mass proportions of thiourea via a simple reflux method. Characterization of the rGO samples by Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDAX) and elemental analysis through CHNS analyzer exhibited successful doping and impact of nitrogen and sulfur atoms on the graphene framework. The comparative electrochemical performance from Cyclic Voltammograms (CV), Galvanostatic Charge Discharge (GCD) profiles and Electrochemical Impedance Spectroscopy (EIS) measurements on the various rGO samples revealed the superiority of 1:8rGO having 15.190 wt% of nitrogen and 26.849 wt% of sulfur and S/N ratio of 1.768, in delivering highest specific capacitance of 465.21 F·g−1 at 1 mV·s−1 scan rate with a remarkable cyclic stability exhibiting a capacitive retention of 119 % and offering lowest charge transfer resistance and diffusion resistance. The study also demonstrated detrimental effect of excess thiourea on electrochemical properties of rGO. This work suggests an effective and simple approach for optimizing the nitrogen and sulfur content in rGO to enhance its electronic properties using thiourea.

Facile and Bioinspired Approach from Gallic Acid for the Synthesis of Biobased Flame Retardant Coatings of Basalt Fibers.

A sustainable, bioinspired approach to functionalize basalt fibers with an innovative gallic acid (GA)-iron phenyl phosphonate complex (BF-GA-FeP), for the purpose of improving the flame retardancy in composite materials, is developed. BFs were at first pretreated with O3, obtaining surface free hydroxyl groups that allowed the subsequent covalent immobilization of biosourced GA units on the fiber through ester linkages. Phenolic -OH groups of the GA units were then exploited for the complexation of iron phenyl phosphonate, resulting in the target-complex-coated BF fiber (BF-GA-FeP). Microwave plasma atomic emission spectroscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analyses of BF-GA-FeP highlighted an increase in iron content, modification of fiber morphology, and occurrence of phosphorus, respectively. BFs, modified with a low amount of the developed complex, were used to reinforce a poly(lactic acid) (PLA) matrix in the production of a biocomposite (PLA/BF-FeP). PLA/BF-FeP showed a higher thermal stability than neat PLA and PLA reinforced with untreated BFs (PLA/BF), as confirmed by thermogravimetric analysis. The cone calorimeter test highlighted several advantages for PLA/BF-FeP, including a prolonged time to ignition, a reduced time to flame out, an 8% decrease in the peak heat release rate, and a 15% reduced fire propagating index compared to PLA/BF.

Suppression of Root Rot Fungal Diseases in Common Beans (Phaseolus vulgaris L.) through the Application of Biologically Synthesized Silver Nanoparticles.

The biosynthesis of silver nanoparticles (AgNPs) using plant extracts has become a safe replacement for conventional chemical synthesis methods to fight plant pathogens. In this study, the antifungal activity of biosynthesized AgNPs was evaluated both in vitro and under greenhouse conditions against root rot fungi of common beans (Phaseolus vulgaris L.), including Macrophomina phaseolina, Pythium graminicola, Rhizoctonia solani, and Sclerotium rolfsii. Among the eleven biosynthesized AgNPs, those synthesized using Alhagi graecorum plant extract displayed the highest efficacy in suppressing those fungi. The findings showed that using AgNPs made with A. graecorum at a concentration of 100 μg/mL greatly slowed down the growth of mycelium for R. solani, P. graminicola, S. rolfsii, and M. phaseolina by 92.60%, 94.44%, 75.93%, and 79.63%, respectively. Additionally, the minimum inhibitory concentration (75 μg/mL) of AgNPs synthesized by A. graecorum was very effective against all of these fungi, lowering the pre-emergence damping-off, post-emergence damping-off, and disease percent and severity in vitro and greenhouse conditions. Additionally, the treatment with AgNPs led to increased root length, shoot length, fresh weight, dry weight, and vigor index of bean seedlings compared to the control group. The synthesis of nanoparticles using A. graecorum was confirmed using various physicochemical techniques, including UV spectroscopy, Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) analysis. Collectively, the findings of this study highlight the potential of AgNPs as an effective and environmentally sustainable approach for controlling root rot fungi in beans.

Investigation the optical and structural properties of Mn-doped Sb2S3 nanocrystals embedded in host glass

The search for earth-abundant and non-toxic elements is essential for the manufacture of sustainable optical devices. In this context, dilute magnetic semiconductor (DMS) xMn-doped Sb2S3 nanocrystals (NCs) embedded in host glass were synthesized by the fusion method. Differential Thermal Analysis shows evidence of Sb2S3 phase crystallization peak and changes in glass transition and crystallization temperatures of the host glass with the presence of xMn-doped Sb2S3 NCs. Transmission electron microscopy images show the formation of xMn-doped Sb2S3 NCs with increasing size (2.1–3.8 nm) as a function of concentration (x = 0.00 to 0.40), respectively. X-ray diffraction measurements reinforced the evidence for the orthorhombic structure of xMn-doped Sb2S3 NCs embedded in glass. Energy dispersive X-ray spectroscopy analyses confirm the S, Sb and Mn precursor elements of DMS NCs. Atomic and magnetic force microscopy measurements show the magnetic contrast patterns resulting from the incorporation of Mn atoms into the Sb2S3 structure. The electronic paramagnetic resonance spectrum confirms the presence of Mn2+ ions (3d5) located in the crystal field of the Sb2S3 semiconductor due to six hyperfine transitions. The redshift of the Raman vibrational mode (1Ag) with increasing xMn concentration gives strong evidence for the presence of Mn2+ ions in sulfur vacancies (VS) in the Sb2S3 unit cell. Optical absorption and photoluminescence (PL) spectroscopy measurements for xMn-doped Sb2S3 NCs show the subtle tunable redshift of the band gap and excitonic recombination in the green-red region, with increasing x concentration. PL confirms that dopant Mn2+ ions fill VS2 that are dominant in Sb2S3. Therefore, the position of the energy states after the increasing concentration of Mn2+ dopant ions gives rise to insight into luminescence for future research scenarios and applications involving sustainable DMS NCs.

Fabrication of single-step novel synthesis of ZnCd(S0.5Se0.5)2 thin films for photoelectrochemical (PEC) cell application

In our study, we use a new method called the arrested precipitation technique (APT) to create CdZn(SSe)2 (CZSS) thin films. We obtain samples at different deposition times, ranging from 2.5 to 4 h, and analyze the effects of deposition time on the opto-structural, morphological, compositional, and photoelectrochemical (PEC) solar cell properties. As a result, we find that the band gap energy increases from 2.366 to 2.60 eV with prolonged growth time, as shown by UV–Vis spectra. X-ray diffraction (XRD) analysis confirms that the crystal structure is hexagonal, with the crystallite size increasing from 76 to 93 nm. The dislocation density and microstrain, determined by the Scherrer formula, decrease from 1.72 to 1.14 lines m−2 and from 4.75 × 10−3 to 3.87 × 10−3 (lines m−2), respectively. These results are validated using the Williamson-Hall (WH) plot and size-strain plot. The average grain size, evaluated using the standard scale bar method in scanning electron microscopy (SEM), ranges from 80 to 150 nm across CZ1 to CZ4 samples. Transmission electron microscopy (TEM) images of CZ4 and CZ2 reveal particle sizes of 101 nm and 87 nm, respectively, while selected area electron diffraction (SAED) patterns confirm the polycrystalline nature of the material. Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses confirm the presence of Cd, Zn, S, and Se elements in their intended stoichiometry. Notably, CZSS photoelectrodes deposited over 4 h show better performance in Photoelectrochemical cells (PEC), achieving the highest photoconversion efficiency (ɳ) at 2.33 %, as evidenced by J-V measurements.

Evaluation of Antibacterial Efficacy of Centella asiatica-Mediated Selenium Oxide Nanoparticles Against Multidrug-Resistant Upper Respiratory Isolates.

Background The evolution of new respiratory diseases, especially upper respiratory tract infections and resistance of pathogens to various antibiotic treatments, needs an alternative way of medication. Chronic respiratory infections in both adults and infants are the major cause of morbidity and mortality, particularly in developing countries. The widespread application of nanomaterials in the field of medicine and the incorporation of nanoparticles in drugs are taken into account. These nanomaterials are involved along with the biosynthesis of plant extract. In this study, selenium oxide nanoparticles (SeO-NPs), known as a significant trace element for human health, were synthesized in an eco-friendly manner. Methodology Green synthesis of Centella asiatica-mediated SeO-NPs was proceeded by titration method and nanoparticles were synthesized. The color intensity, morphological characters, functional properties, and involvement ofphytochemical compounds were studied by using UV-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis. Results The synthesized extract showed a color change from brown to ruby red. Results obtained by characterization and biological assays depicted that the Centella asiatica-mediated SeO-NPs showed absorbance at the peak level 320 nm by UV-Vis spectroscopy, several phytochemical compounds, and O-H functional groups by FT-IR which may be involved in the reduction of the selenium oxide nanoparticles. The XRD showed 57.1% crystalline and 42.6% amorphous nature. The SEM images showed that agglomerated spherical shapes were involved in biological activities. The EDX analysis showed the presence of Se, C, and O compounds. Further, the antibacterial activity of the synthesized nanoparticles showed significant activity in the multidrug-resistant respiratory pathogens. Conclusions Based on the characterization studies and biomedical assays, it can be concluded that the incorporation of SeO-NPs along with the plant extract serves as the best remedy and organic treatment for upper respiratory tract infections. We plan to conduct further in-vivo, toxicity-level studies, and clinical trials.

Synthesis of Cd-Cu nanoparticles supported on HOPG for use as electrocatalytic material for nitrate reduction

Bimetallic nanoparticles application has attracted great attention in the field of electrocatalysis because they can enhance the catalytic properties toward certain reactions of technological interest, such as nitrate reduction. For this purpose, Cd-Cu bimetallic nanoparticles were prepared on highly oriented pyrolytic graphite substrates by sequential electrodeposition of both metals. The process was studied by conventional electrochemical techniques, and the generated deposits were characterized by scanning electron microscopy − energy dispersive X-ray spectroscopy analysis. Initially, Cu nanoparticles were prepared by a simple potentiostatic pulse applied to the carbonaceous substrate. Scanning electron microscopy images showed high density of mainly hemispherical-shaped Cu crystals distributed preferably on step edges and surface defects of the highly oriented pyrolytic graphite electrode. Subsequently, Cd particles were prepared in the same way by immersing the Cu nanoparticles / highly oriented pyrolytic graphite modified substrate in an electrolyte solution containing Cd2+ ions, exploiting the phenomenon of underpotential deposition. It was evidenced that the existing crystals grew in size, most of them showing the typical shapes of those for Cd nanoparticles. The application of the Cd-Cu nanoparticles / highly oriented pyrolytic graphite electrode as a feasible electrocatalyst material for nitrate reduction was investigated by cyclic voltammetry for different nitrate concentrations, also considering the possibility of using this procedure as a method for the anion detection.

From the sea to the land: How microbial mats dominated marine and continental environments in the Ediacaran Camaquã Basin, Brazil

Precambrian sedimentary successions exposed worldwide record microbial deposits within both marine and continental strata. The Camaquã Basin records the transition from the Ediacaran to Cambrian periods in strata that comprise marine to lacustrine environments. The Camaquã Basin fossils comprise microbial mats and organic-walled microfossils in very close association. Carbonaceous laminae are common within the siltstone and mudstone layers and represent remarkably well-preserved Ediacaran microbial mats. These mats occurred along shallow marine through deep and shallow lake settings. The excellent preservation of these structures seems to be the product of calm hydrodynamic conditions and floodings. These hydrodynamic undisturbed environments allowed microbial mat growth. Besides, episodic floodings brought clay particles, which deposits guaranteed isolation from organic decomposition of mats. In general, the siltstones and mudstones record microbially induced sedimentary structures (MISS) that are typical from Ediacaran strata, such as wrinkle marks and elephant skin structures. Our research revealed that the occurrence of these structures is not limited to marine settings, as common in records from this period, but also present in lacustrine environments. Field studies were combined with optical and scanning electron microscopy plus energy-dispersive X-ray spectroscopy (SEM-EDS) analyses to demonstrate the vast occurrence of microbial mats along the deposits that registered the Camaquã Basin development. Geochemical data (whole-rock and total organic carbon (TOC) analyses) contribute to improving sedimentological descriptions, bringing light regarding the depositional environment where these microbial communities have developed. The excellent preservation state of organic matter on these marine and lacustrine siliciclastic sequences represents an impressive record in a Proto-Gondwana basin.

Comparative Analysis of Endodontic ISO Size 06, 08, and 10 Stainless Steel K-Files Used for Glide Path Procedures.

Small-sized stainless steel hand files are conventionally employed in root canal treatment procedures for canal scouting and for glide path establishment, owing to their superior flexibility and proficiency in navigating confined spaces. Given the diversity of brands available in the market, there exists potential variability in their physical characteristics, thereby influencing clinical performance. Consequently, this study aims to conduct a comparative analysis of the design, metallurgy, and mechanical characteristics among seven stainless steel hand file brands across ISO sizes 06, 08, and 10. A total of 315 new 25 mm length stainless steel hand files with apical sizes of 0.06, 0.08, and 0.10 from seven distinct brands were included in the study. A meticulous inspection of all instruments was undertaken to identify any structural deformations that might render them ineligible for the study. The design inspection involved the random selection of instruments from each group, which were examined under various microscopes, including a dental operating microscope, optical microscope, and scanning electron microscope. Furthermore, two instruments from each group underwent energy-dispersive X-ray spectroscopy analysis for elemental composition documentation. Mechanical tests were conducted to evaluate the instruments' resistance to lateral deformation (buckling) and their microhardness. Statistical analysis was executed using the nonparametric Mood's median test, with a predetermined significance level of 0.05. Regarding the instruments design, all files exhibited an active blade length ranging from 16 to 17 mm. However, variations were observed in the number of spirals, tip designs, and sizes, with the API K-File notably larger in sizes 0.06 and 0.08 compared to the other instruments. Despite uniform elements composition, differences in geometric features and mechanical properties were evident. Concerning buckling strength, the API K-File demonstrated superior performance across all tested sizes, while the Dentsply ReadySteel, SybronEndo, and Mani K-Files exhibited lower results (p < 0.05). In microhardness assessments, both the API and Oro K-Files displayed the lowest outcomes, with medians of 531 HVN and 532 HVN, respectively, whereas the SybronEndo K-File exhibited the highest microhardness (657 HVN). Despite similar metallurgical composition, the observed distinctions in geometric features and mechanical properties underscore the impact of the manufacturing process on the characteristics of glide path stainless steel endodontic files. These disparities may ultimately influence their clinical performance.

Aluminium substitution affects jarosite transformation to iron oxyhydroxides in the presence of aqueous Fe(II)

Jarosite is an abundant mineral in acidic environments, often found in acid sulfate soil (ASS) and acid-mine drainage (AMD). As a store of Fe, K, S and acidity, and a scavenger for major and trace elements, jarosite plays an important role in the biogeochemistry of acid sulfate environments. When ASS and AMD become anoxic, reducing conditions can set in, producing conditions that are outside the thermodynamic stability field of jarosite. In this study, we investigated the transformation of synthetic and natural jarosite with various degrees of Al-for-Fe substitution under circumneutral anoxic conditions in the presence of Fe(II), to understand the rates and pathways of jarosite and Al-jarosite transformation, the role of competing transformation pathways, the fate of Al during transformation and the different reactivity of natural and synthetic Al-jarosite. Synthetic jarosite (containing 0 %–7 % Al-for-Fe substitution) and a natural Al-substituted jarosite sample from an ASS in Thailand were suspended in solutions of 57Fe(II) at pH 7 for 24 h under anoxic conditions. The chosen experimental conditions mimic the Fe(II) concentrations and pH found in flooded ASS under reducing conditions. Changes in mineral composition of the suspensions were determined by Rietveld analysis of X-ray diffraction patterns at six time points. The fate of Al was determined by XRD, Raman spectroscopy and energy dispersive X-ray spectroscopy analysis of the jarosite and product minerals. Different transformation pathways that occurred simultaneously were traced by using 57Fe Mössbauer spectroscopy and aqueous Fe isotope composition. The analysis showed that 7 % Al-for-Fe substitution in jarosite more than halved the mineral transformation rate compared to unsubstituted jarosite, regardless of the Fe(II) concentrations. Indeed, 7 % Al-for-Fe substitution had a greater effect on the transformation rate than an order-of-magnitude decrease in the Fe(II) concentrations in all Al-for-Fe substitution treatments. The transformation products in all samples were goethite, lepidocrocite and ferrihydrite, with minor amounts of magnetite forming from jarosite with no or low Al-for-Fe substitution reacted with high Fe(II) concentrations. Lepidocrocite was the dominant product in reactors without aluminium, but lepidocrocite was not strongly enriched in 57Fe, suggesting that it may not have formed exclusively from Fe in solution during the Fe(II)-catalysed transformation of other minerals. In high-Al systems, lepidocrocite appeared to be a sink for Al, although its formation in Al-rich samples was suppressed. Natural jarosite reacted more than an order of magnitude more slowly than the synthetic jarosite and Al-jarosite, indicating that the properties of the synthetic jarosite do not completely account for the stability of natural jarosite under anoxic circumneutral conditions. The results provide an important baseline for understanding the drivers of jarosite transformation or stability in ASS and AMD.

Microwave-assisted extraction of lithium from hectorite clay

ABSTRACT Transition to renewable energy sources, rapid rise in the use of Li-ion batteries for energy storage has warranted a search for efficient lithium extraction methods from low grade lithium ores such as clays and sediments since supply from conventional sources is insufficient to meet the increasing demand. In this effort, classical base – acid – carbonate method was found to be ineffective for the extraction of lithium from minerals with very low lithium content such as hectorite clay with of 0.137 ± 0.004 % (w/w) lithium. The key finding in this work is a new microwave heating assisted base – acid – carbonate method for the extraction of lithium from low lithium content clay minerals, where lithium could be extracted from hectorite clay mineral in 98% efficiency as lithium carbonate. Leaching of lithium from hectorite clay was evaluated by studying Scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) analyses, ATR-IR and X-ray crystallography of hectorite and leach residues.

Crystallographic and band structure analysis of β-(AlxGa1−x)2O3/β-(InyGa1−y)2O3 thin film grown on β-Ga2O3 substrate via mist CVD

We successfully achieved the growth of a stacked layer composed of β-(AlxGa1−x)2O3/β-(InyGa1−y)2O3 on a (010) β-Ga2O3 substrate using mist chemical vapor deposition (CVD). X-ray diffraction and reciprocal space mapping analyses were conducted, elucidating that the multilayer structure of the β-(AlxGa1−x)2O3/β-(InyGa1−y)2O3 thin film exhibited excellent crystallinity and coherent growth. Scanning transmission electron microscopy further revealed a continuous atomic arrangement at the heterointerface of β-(AlxGa1−x)2O3/β-(InyGa1−y)2O3. Furthermore, the bandgap values of β-(AlxGa1−x)2O3 and β-(InyGa1−y)2O3 thin films were determined to be 5.21 and 4.62 eV, respectively, through electron energy-loss spectroscopy. Notably, a slight broadening was observed in the bandgap transition at the interface of β-(AlxGa1−x)2O3/β-(InyGa1−y)2O3. Energy dispersive x-ray spectroscopy analysis indicated that this phenomenon could be attributed to the diffusion of In into the β-(AlxGa1−x)2O3 thin film layer. These results support mist CVD as a promising growth technique for developing β-Ga2O3-based heterojunction devices.

On dry machining of AZ31B magnesium alloy using textured cutting tool inserts

Magnesium alloys have many advantages as lightweight materials for engineering applications, especially in the fields of automotive and aerospace. They undergo extensive cutting or machining while making products out of them. Dry cutting, a sustainable machining method, causes more friction and adhesion at the tool-chip interface. One of the promising solutions to this problem is cutting tool surface texturing, which can reduce tool wear and friction in dry cutting and improve machining performance. This paper aims to investigate the impact of dimple textures (made on the flank face of cutting inserts) on tool wear and chip morphology in the dry machining of AZ31B magnesium alloy. The results show that the cutting speed was the most significant factor affecting tool flank wear, followed by feed rate and cutting depth. The tool wear mechanism was examined using scanning electron microscope (SEM) images and energy dispersive X-ray spectroscopy (EDS) analysis reports, which showed that at low cutting speed, the main wear mechanism was abrasion, while at high speed, it was adhesion. The chips are discontinuous at low cutting speeds, while continuous at high cutting speeds. The dimple textured flank face cutting tools facilitate the dry machining of AZ31B magnesium alloy and contribute to ecological benefits.

Formation mechanism of a novel core–shell with tetradecyl dimethyl benzyl ammonium–modified montmorillonite interlayer nanofibrous membrane and its antimicrobial properties

A novel core–shell with a tetradecyl dimethyl benzyl ammonium chloride–modified montmorillonite (TDMBA/MMT) interlayer silk fibroin (SF)/poly(lactic acid) (PLLA) nanofibrous membrane was fabricated using a simple conventional electrospinning method. Scanning electron microscopy and pore size analyses revealed that this core–shell with TDMBA/MMT interlayer maintained its nanofibrous morphology and larger pore structure more successfully than SF/PLLA nanofibrous membranes after treatment with 75% ethanol vapor. Transmission electron microscopy and energy-dispersive X-ray spectroscopy analyses testified that the SF/PLLA–TDMBA/MMT nanofibers exhibited a core–shell with an interlayer structure, with SF/PLLA in the core–shell layer and TDMBA/MMT in the interlayer. The formation of a core–shell with interlayer nanofibers was primarily attributed to the uniform dispersion of TDMBA/MMT nanosheets in a solution owing to its exfoliation using hexafluoroisopropanol and then preparing a stable spinning solution similar to an emulsion. Compared to SF/PLLA nanofibrous membranes, the core–shell structure with TDMBA/MMT interlayers of SF/PLLA nanofibrous membranes exhibited enhanced hydrophilicity, thermal stability, mechanical properties as well as improved and long-lasting antimicrobial performance against Escherichia coli and Staphylococcus aureus without cytotoxicity.

Enhancing the capabilities of Mg–4Zn-1RE-0.7Zr alloy through synergistic integration of ceramic (ZrO2) & solid lubricant (BN/MoS2) reinforcements: A Taguchi-GRA optimization approach

In this present investigation, novel hybrid magnesium composites were synthesized by the inclusion of self-lubricating (BN/MoS2) and ceramic (ZrO2) particulates with the help of the powder metallurgy technique. ZE41 magnesium (Mg–4Zn-1RE-0.7Zr) was applied for a broad range of components, including the gearbox casing, the framework of the door, and transmission in aircraft like the Sikorsky UH-60 and the Boeing 727. Apart from its structural application, its usage was limited because of its deficient wear and mechanical properties. This research focuses on enhancing the potential applications of the ZE41 magnesium alloy by improving its mechanical and tribological characteristics. The design of the experiment scheme was applied to explore the effect of individual reinforcements and their synergistic effects on various properties of prepared composites. Microstructural inspection was employed to inspect the morphological characteristics of prepared specimens through scanning electron microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD). By analysing SEM, EDS, and X-ray diffraction patterns, the microstructural evaluation reveals uniform phase dispersion and the existence of reinforcements with some minor defects. As a result of the inclusion of reinforcements in composites, the hardness of the reinforced specimen improved to 39.65%, while the wear rate of the reinforced specimen decreased to 40.90% compared with monolithic alloy. A multi-objective grey relational analysis (GRA) optimization method was used to perform a detailed tribological analysis on Specimen G (ZE41 mg + 3% ZrO2 + 3% MoS2). According to the results of GRA, the optimized rate of wear and frictional coefficient were achieved on sliding velocity (4 ms−1), sliding distance (2000 m), and load (10 N). The worn surface micrograph reveals that the reinforced composite underwent abrasion and delamination wear, while the unreinforced alloy experienced plastic deformation.

Synergistic protection of borate and silicate salts composite for controlling the chloride-induced pitting and uniform corrosion of steel reinforcement bars embedded in mortars

In this study, the efficacy of the combined effect of borate and silicate alkali metal salts added to mortars for controlling the chloride-induced uniform and localized corrosion of embedded steel rebars is examined. The individually added salts in mortars are found to have insignificant effects in terms of reducing the uniform corrosion rate and localized damage. However, their combination (0.50% sodium tetra borate + 0.10% sodium silicate added with respect to the weight of the binder) provides complete protection to reinforcements tested for long durations under wet/dry treatments with mortars in saline water and laboratory atmospheres. Electrochemical impedance spectroscopy, direct current cyclic polarization, polarization resistance, and visual observations are used for quantitative and qualitative evaluations of the protective effects of the tested additives. X-ray diffraction analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy analysis of the corrosion products formed on the embedded steel surfaces help explain the possible mechanisms behind the considerable improvement in the inhibitive effects of a mixed composition of borate and silicate. This combination also improves the compressive strength and workability of the mixed concrete. The results reveal that the synergistic protection provided by a mixture of borate and silicate can be attributed to the co-deposition of an iron-boron + ferrosilicate + cortensitite (an iron-silicon phase) film on the rebar surface.