Energy Dispersive Electron Research Articles

Biology in its Element: Using Energy Dispersive X-ray Spectroscopy Scanning Transmission Electron Microscopy (EDX-STEM) to Probe Bacterial Ultrastructure

Biology in its Element: Using Energy Dispersive X-ray Spectroscopy Scanning Transmission Electron Microscopy (EDX-STEM) to Probe Bacterial Ultrastructure

Implementation of a control and monitoring system for a cathodic protection cell to mitigate localized corrosion in fixed and mobile steel structures

The current study introduces a novel technique to handle electrochemical localized corrosion in certain limited regions rather than applying comprehensive cathodic protection (CP) treatment. An impressed current cathodic protection cell (ICCPC) was fabricated and firmly installed on the middle of a steel structure surface to deter localized corrosion in fixed or mobile steel structures. The designed ICCPC comprises three essential parts: an anode, a cathode, and an artificial electrolyte. The latter was developed to mimic the function of the natural electrolyte in CP. A proportional-integrated-derivative (PID) controller was designed to stabilize this potential below the ICCPC at a cathodic potential of −850 mV, which is crucial for protection efficacy. The controller of the protection system was designed to automatically activate the ICCPC when the environment of the steel structure is exposed to humidity. At a temperature range from 27 °C to 35 °C, the protection potential, current, and power showed an increase in percentage by 411 %, 688.74 %, and 2842.3 %, respectively when the humidity level rose from 10 % to 100 %. The intended spraying of sodium chloride (NaCl) solution on the structure at different concentrations from 1.5 % to 5 % showed excellent protection against corrosion, notable improvements in electrical conductivity, and reduction in resistance between the anode and cathode. The energy dispersive spectroscopy and scanning electron microscopy (SEM-EDS) analyses confirm effective corrosion inhibition under ICCPC coverage compared to unprotected areas. These tests revealed an absence of oxidation beneath the ICCPC compared with areas outside of its coverage. The areas outside of ICCPC protection showed a reduction in iron and carbon contents from 57.1 % to 47.0 % and 41.4 %–22.4 %, respectively, and an increase in oxygen from 1.6 % to 30.6 %.

Microstructure and oxidation of a Ni–Al based intermetallic coating formation on a Monel-400 alloy

Abstract The purpose of this work was to examine how the microstructure and oxidation characteristics of Monel 400 Alloy were affected by the low-temperature aluminizing method. Monel 400 alloy was subjected to a low-temperature aluminizing procedure for 2 and 4 h at 600, 650, and 700 °C. Pure aluminum powder was used as the source of aluminum deposition to prepare the packs for the process. The activator and inert filler utilized were ammonium chloride (NH4Cl) and Al2O3 powder, respectively. The coating surfaces were characterized using energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM), as well as X-ray diffraction (XRD) analysis. It was discovered that the through-thickness variance in the layer microstructure varied between 4 and 30 µm, and that it increased with greater process temperatures and times. The coating layer hardness grew to 800 HV after the deposition process, whereas the matrix hardness remained at 200 HVN. Furthermore, the sample that was coated at 600 °C for 4 h was exposed to oxidation at 750–800 and 850 °C. It was found that the oxidation kinetics were 176 kJ/mol.

Heteroatom doped biochar-aluminosilicate composite as a green alternative for the removal of hazardous dyes: Functional characterization and modeling studies

In this work, a novel nitrogen-doped biochar bentonite composite was synthesized by a single-pot co-pyrolysis method. Batch studies were conducted to evaluate the performance of the developed composite in eliminating synthetic dyes from the aqueous matrix. Energy dispersive X-ray spectroscopy analysis and field emission scanning electron microscopy imaging confirmed the N doping and bentonite impregnation into biochar. X-ray photoelectron spectroscopy analysis revealed that the N atoms were doped interstitially into the carbon matrix of biochar in the form of pyridinic and pyrrolic nitrogen. Simultaneous heteroatom doping and bentonite impregnation reduced the specific surface area to 41.721 m2 g−1 but improved the adsorption capacity of biochar for dye adsorption. Further experimental studies depicted that simultaneous bentonite impregnation and N doping into the biochar matrix is beneficial for direct blue-6 (DB-6) and methylene blue (MB) removal and maximum adsorption capacities of 53.17 mg. g−1 and 41.33 mg. g−1 were obtained for MB and DB-6, respectively, at varying conditions. Adsorption energetics of the dyes with the developed composite portrayed the spontaneity of the process through negative ΔG values. The Langmuir and Freundlich isotherm models fitted the best for MB and DB-6 adsorption. The monolayer adsorption capacity and favourability factor for MB and DB-6 adsorption were calculated to be 54.15 mg. g−1 and 0.217, respectively from the best-fitted isotherms. Based on density functional theory calculations and spectroscopic studies, major interactions governing the adsorption were predicted to be charge-based interactions, π-π interactions, H-bonding, and Lewis acid-base interactions.

Friction stir processing of AA6061-T6/graphene nanocomposites: Unraveling the influence of tool geometry, rotation, and advancing speed on microstructure and mechanical properties

This research investigated the effect of tool geometry, rotation, and advancing speed on the microstructure and mechanical properties of aluminum AA6061-T6/graphene nanocomposites fabricated by friction stir processing (FSP) using three conical tools with the pin cone angles (PCAs) of 2, 2.5, and 3°. In the first step of the study, the process was performed with and without graphene nanoplatelets (GNPs) at different rotations (710, 1120, and 1400 rpm) and advancing speeds (80, 125, and 160 mm/min). The yield strength, tensile strength, and microhardness of all the samples were lower than those of the base metal. In the second step of the study, the heat input was controlled by reducing rotations (112, 180, and 280 rpm) and advancing speeds (31.5, 25, and 20 mm/min). The mechanical properties of processed samples were studied by tensile tests and microhardness measurements. Microstructural evolution in samples was analyzed by means of a field emission scanning electron microscope (FESEM) equipped with an X-ray energy dispersive spectrometer (EDS) and electron back-scattered diffraction (EBSD) detector. The results indicated that the mechanical properties were improved in the second step with the increase in the advance per revolution (APR) and the PCA. This was linked to the microstructure evolution in the processed samples affected by process parameters and regulated heat input. The effect of each input variable on the mechanical properties was evaluated by statistical analysis and was validated by analysis of variance (ANOVA). The optimal processing was attained by utilization of PCA, tool rotation, and advancing speed.

Development of large-size dissimilar stainless steel/α-Ti alloy joints by diffusion bonding using vacuum hot press: Interface microstructure and tensile response in the temperature range of 77–773 K

In the present study, dissimilar metal joints of SS321 and Ti–5Al-2.5Sn (α-Ti alloy) are produced by diffusion bonding at temperatures of 850, 900, and 950 °C under 10 MPa pressure for 30 min duration using a vacuum hot press (VHP). The interface of the joints was characterized through scanning electron microscopy coupled with energy dispersive spectroscopy and electron backscattered diffraction analysis for examining microstructure, morphology, and microchemistry across the interface. The effect of change in the heating process during diffusion bonding on the growth kinetics of interface layers was investigated. The interface of the joints comprised of intermetallic phases of σ phase, χ phase, (Fe,Cr)2Ti, FeTi and β-Ti. The joint produced at 900 °C has exhibited a maximum tensile strength of 315 MPa, 253 MPa, and 208 MPa at the test temperatures of −196 °C (77 K), room temperature (300 K), and 500 °C (773 K), respectively. Reduction in joint strength was noticed at test temperatures of RT and −196 °C for the samples bonded at a higher temperature of 950 °C due to the increased widths of the intermetallic phases at the interface. The effect of the bonding temperature on the tensile strength of the joints at an elevated test temperature of 500 °C was found to be negligible; however, the joints displayed good retention of strength along with substantial strain hardening followed by ductility at 500 °C. Fracture surfaces of RT and −196 °C tested samples showed the mixed mode of featureless smooth and cleavage fracture, whereas the 500 °C tested sample displayed planar interface failure. The zone of failure of the joints was noted to be around the interphase layer made of (Fe,Cr)2Ti + FeTi intermetallics.

Effect of bath temperature on electroplating of nickel on a copper substrate

ABSTRACT Nickel electroplating is known to be industrially effective for enhancing various substrate properties. In the present work, nickel coatings were developed on copper substrates by electroplating using standard nickel plating solution at various electrolyte bath temperatures ranging from 40 ± 2°C to 60 ± 2°C in steps of 10°C. Energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to study the composition, phase structure and morphology of the coatings. The coatings were also analysed for hardness and porosity, and process current efficiency was measured. The electrolyte bath temperature has a profound effect on the nature of the developed nickel coatings, and is observed to have an impact on the surface morphology, crystallographic direction, and hardness, as well as deposition current efficiency.

Electrochemical modification of the Ti[sbnd]15Mo alloy surface in solutions containing Ag2O, Ag3PO4 and Ca3(PO4)2 particles

Implants with bioactive coatings are becoming increasingly popular in bioengineering. The incorporation of silver nanoparticles into the oxide layer supports the antibacterial effect. This article describes the surface modification of Ti15Mo alloy subjected to the plasma electrochemical oxidation (PEO) process in baths containing Ag compounds: Ag2O, Ag3PO4, and Ag3PO4+ Ca(PO4)2 to incorporate antibacterial silver particles into the oxide layer on the surface of the tested alloy. Scanning electron microscopy revealed changes in the surface porosity of the obtained oxide layers. Energy dispersive analysis, Raman spectroscopy, and X-ray electron spectroscopy determined the chemical composition and distribution of elements on the sample's surface. The tests showed the presence of embedded silver particles and uniform distribution on the surface. The bioactivity of the obtained layer was tested by adhesion tests of bacteria and fungi: Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), and Candida albicans (ATCC 2091).

High-temperature hardness and scratch behaviour of differently strengthened iron aluminide laser claddings

Fe3Al-based iron aluminides provide notable high-temperature properties at a comparatively low overall ecological impact. To improve their wear resistance, different strengthening strategies are studied for which Fe3Al-based laser claddings (30 at.% Al) are alloyed either with Si, C, or Ti and B. Detailed microstructural investigations after laser metal deposition (LMD) including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) were performed. Results show that Si-alloyed claddings are single-phase with equiaxed grains of average sizes from ∼350 μm (1 at.% Si) decreasing with increasing Si content to ∼50 μm at 3 and 5 at.% Si. Contrary, the C-alloyed claddings microstructures are dendritic and ledeburite-like with perovskite-type carbides Fe3AlC0.6. The Ti- and B-alloyed cladding exhibits finely dispersed TiB2-type precipitations; at low contents in the sub-micron range and mainly present at the grain boundaries, at higher additions are quite large (3–5 μm) and present within individual grains. The individual hardphases, as quantified via nanoindentation, of Fe3AlC0.6-type carbides or TiB2-type borides exhibit average hardness values of ∼7.5 GPa and ∼ 45.5 GPa, respectively. Therefore, the hardness of C- and Ti & B-alloyed claddings increases from ∼260 HV10 (Fe3Al) to 405 HV10 (Fe3Al plus 5 at.% C) and to 340 HV10 (Fe3Al plus 3 at.% and 6 at.% B). The higher hardness of the C-alloyed cladding stems from the s higher hardphase content; the matrix hardness ranges between 4 and 5 GPa for all precipitation-strengthened claddings. Contrary, the Si-alloyed cladding exhibits a pronounced increase to 5.7 ± 0.8 GPa upon adding up to 5 at.% Si. Thus, an overall hardness of ∼350 HV10 is quantified on the expense of ductility (relaxation cracking after LMD). High-temperature hardness and scratch tests as well as wear investigations prove that the C- as well as Ti and B-alloyed claddings are superior to the plain Fe3Al and Si-alloyed ones, making them promising alternatives to other wear protection materials based on Co, Ni or Cr.

Effect of multiple firings on optical and mechanical properties of Virgilite-containing lithium disilicate glass-ceramic of varying thickness

ObjectivesTo investigate the effect of multiple firings on color, translucency, and biaxial flexure strength of Virgilite-containing (Li0.5Al0.5Si2.5O6) lithium disilicate glass ceramics of varying thickness.Materials and methodsSixty discs were prepared from Virgilite-containing lithium disilicate blocks. Discs were divided according to thickness (n = 30) into T0.5 (0.5 mm) and T1.0 (1.0 mm). Each thickness was divided according to the number of firing cycles (n = 10); F1 (Control group): 1 firing cycle; F3: 3 firing cycles, and F5: 5 firing cycles. The discs were tested for color change (ΔE00) and translucency (TP00) using a spectrophotometer. Then, all samples were subjected to biaxial flexure strength testing using a universal testing machine. Data were collected and statistically analyzed (α = 0.5). For chemical analysis, six additional T0.5 discs (2 for each firing cycle) were prepared; for each firing cycle one disc was subjected to X-ray diffraction analysis (XRD) and another disc was subjected to Energy dispersive X-ray spectroscopy (EDX) and Scanning electron microscope (SEM).ResultsRepeated firing significantly reduced the translucency of F3 and F5 compared to F1 in T0.5 (p < 0.001), while for T1.0 only F5 showed a significant decrease in TP00 (p < 0.001). For ΔE00, a significant increase was recorded with repeated firings (p < 0.05) while a significant decrease resulted in the biaxial flexure strength regardless of thickness.ConclusionsRepeated firings had a negative effect on both the optical and mechanical properties of the Virgilite-containing lithium disilicate glass ceramics.Clinical relevanceRepeated firings should be avoided with Virgilite-containing lithium disilicate ceramics to decrease fracture liability and preserve restoration esthetics.

Biodegradation behavior of wool and other textile fibers in aerobic composting conditions

AbstractPollution of the environment by microscopic fragments of plastic is a growing environmental concern. A category of this pollution is fiber fragments from textiles, a source of which is believed to be fibers released by clothing made of synthetic fibers during laundering. These fragments could enter the environment at the end of the textile’s useful life if it is not re-used or recycled. Disposal of biodegradable fibers could be achieved by industrial composting, but natural fibers are sometimes modified during manufacturing in ways that might influence biodegradation. The composting behavior of fabrics made with unmodified and chemically modified wool fibers (chlorine-Hercosett treated), regenerated cellulose, and several synthetic fibers was compared in industrial composting conditions according to an established standard test method. The fabrics were characterized by Fourier transform infrared spectroscopy, energy dispersive X-ray and electron microscopy. The regenerated cellulose (viscose rayon) biodegraded to the greatest extent in the test, and both types of wool also biodegraded readily. All three synthetic fibers had no biodegradation. The machine-washable wool biodegraded more rapidly than unmodified wool and analysis of residues at the conclusion of the test indicated that it did not generate non-degradable fiber fragments. The epicuticle of unmodified wool is covered with a hydrophobic layer, which may resist microbial attack, but with time this slowly degraded. Conversely, the machine-washable wool is hydrophilic and therefore was easier for microbes to attack. If not re-used, commercial, machine-washable wool textiles can be readily disposed of in industrial composting conditions.

Effect of Ti content on microstructure and properties of Cu/AgCuTi/Al2O3 brazed joints

In this study, four groups of Ag-Cu-Ti brazing powder with different Ti contents of 2 wt%, 3 wt%, 3.75 wt% and 4 wt% were prepared by vacuum atomization, and then modulated into brazing pastes. Brazing between oxygen-free copper and alumina ceramics with the brazing pastes and the wettability experiments of the brazing pastes on alumina were done by vacuum brazing process at 880℃ for 30 min. Microstructures and wettability of both the braze alloy and joints were analyzed by scanning electron microscope, energy dispersive X-ray spectrometer and transmission electron microscope, and shear strength of the joints was tested by self-designed fixture. Based on thermodynamic calculation and kinetic analysis, the relationship between the products of the reactive layer and the change of Ti content was plotted to explore the reaction and wetting mechanism of AgCuTi braze alloy on alumina ceramics. The results show that the content of Ti in AgCuTi braze alloy is the main factor affecting the brazing performance and wettability of the braze alloy by affecting the products of AgCuTi/Al2O3 reaction layer. The reaction layer consists of TiO when the Ti content is 2 wt%, the reaction layer comprises of TiO and Ti3Cu3O when the Ti content is 3 wt%, the reaction layer is made up of Ti3O2 and Ti3Cu3O when the Ti content is 3.75 wt%, and the reaction layer consists entirely of Ti3Cu3O when the Ti content is 4.6 wt%. With the increase of the Ti content within the range of 2–4.6 wt%, the wettability of the braze alloy on the alumina ceramics improved, and the shear strength of the Cu/AgCuTi/Al2O3 joints increased.

Effects of sintering temperature on the physical, structural, mechanical and antimicrobial properties of extracted hydroxyapatite ceramics from Anabas testudineus bone and head scull for biomedical applications

In this experimental investigation, Hydroxyapatite (HAp) is extracted from bone and head scull of Anabas testudineus by thermal calcination at 800 °C for 5 h under ambient air conditions. Ceramic samples were prepared through compaction and followed by sintering at 1200 °C, 1250 °C, and 1300 °C temperatures for 2 h from the calcined HAp powder. Both the calcined powder and sintered ceramic samples were characterized using X-ray Diffraction (XRD), Energy dispersive X-ray spectroscopy (EDS) and Scanning Electron Microscopy (SEM) to explore the potentiality of the extracted ceramics for biomedical applications. Moreover, the elemental composition, phase structure, compressive strength, Vicker hardness, and antimicrobial characteristics of the ceramic samples have been investigated. The XRD analysis confirmed the presence of hydroxyapatite in both the calcined powder and ceramic samples. Various types of trace elements were observed in HAp ceramics including a noteworthy 1.57 atomic percent of magnesium (Mg). Additionally, the XRD spectrum indicated the existence of the β-tricalcium phosphate (TCP) phase. Upon sintering at a temperature of 1250 °C, the ceramic sample underwent a phase shift to α-TCP. Our results show that the phase transition has a significant effect on the crystallinity of HAp. The ceramics sample sintered at 1300 °C exhibited the highest compressive strength and Vicker Hardness due to its high relative density, well-packed grains, and larger particle size. The sintered sample did not exhibit notable zone of inhibition against Escherichia coli and Staphylococcus aureus bacteria.

Crystallographic structure, antibacterial effect, and catalytic activities of fig extract mediated silver nanoparticles

Silver nanoparticles (Ag NPs) play a pivotal role in the current research landscape due to their extensive applications in engineering, biotechnology, and industry. The aim is to use fig (Ficus hispida Linn. f.) extract (FE) for eco-friendly Ag NPs synthesis, followed by detailed characterization, antibacterial testing, and investigation of bioelectricity generation. This study focuses on the crystallographic features and nanostructures of Ag NPs synthesized from FE. Locally sourced fig was boiled in deionized water, cooled, and doubly filtered. A color change in 45 mL 0.005 M AgNO3 and 5 mL FE after 40 min confirmed the bio-reduction of silver ions to Ag NPs. Acting as a reducing and capping agent, the fig extract ensures a green and sustainable process. Various analyses, including UV–vis absorption spectrophotometry (UV), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray spectroscopy (EDX) and Transmission electron microscopy (TEM) were employed to characterize the synthesized nanoparticles, and Gas chromatography-mass spectrometry (GC-MS) analysis of the fig extract revealed the presence of eleven chemicals. Notably, the Ag NPs exhibited a surface plasmon resonance (SPR) band at 418 nm, confirmed by UV analysis, while FTIR and XRD results highlighted the presence of active functional groups in FE and the crystalline nature of Ag NPs respectively. With an average particle size of 44.57 nm determined by FESEM and a crystalline size of 35.87 nm determined by XRD, the nanoparticles showed strong antibacterial activities against Staphylococcus epidermidis and Escherichia coli. Most importantly, fig fruit extract has been used as the bio-electrolyte solution to generate electricity for the first time in this report. The findings of this report can be the headway of nano-biotechnology in medicinal and device applications.

Eco-Friendly Synthesis of CuO@ZnO Nanocomposites Using Artemisia vulgaris Leaf Extract and Study of Its Photocatalytic Activity for Methylene Blue

In this study, copper oxide nanoparticles (CuO NPs), zinc oxide nanoparticles (ZnO NPs), and copper oxide/zinc oxide nanocomposites (CuO@ZnO NPs) were synthesized by green synthetic route where bioactive compounds inherently present in the leaf extract of Artemisia vulgaris act as stabilizing and reducing agents. Phytochemicals present in leaf extract were assessed by qualitative chemical tests and spectroscopic measurements. UV-visible spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Energy Dispersive X-ray (EDX) spectroscopy, X-ray Diffraction (XRD), and Field Emission Scanning Electron Microscopy (FESEM) were used to characterize the as-synthesized nanomaterials, i.e., CuO, ZnO, and CuO@ZnO NPs. XRD pattern revealed the crystalline nature of nanoparticles. Based on the Debye–Scherrer formula, the sizes of CuO NPs, ZnO NPs, and CuO@ZnO NCs were found to be 17.24, 20.74, and 22.50 nm, respectively. The band gap of the as-prepared nanomaterials was measured using the Tauc plot. Using the nanomaterials, MB degradation was studied at room temperature under exposure to UV light. The degradation efficiency of CuO, ZnO, and 2% CuO@ZnO was found to be 52%, 68%, and 98%, respectively. Kinetic degradation process reveals that the CuO@ZnO NCs showed a better photocatalytic activity on MB dye with the degradation constant of 0.04124 min−1 compared to those of either constituent. Based on the findings, it was found that CuO@ZnO nanocomposites have the potential to degrade MB as an organic dye and can be used for wastewater treatment.

Microscopic insights into metal diffusion and ohmic contact formation in delta-doped GaAs/(Al,Ga)As core/shell nanowires

Semiconductor nanowires (NWs) are promising candidates for use in electronic and optoelectronic applications, offering numerous advantages over their thin film counterparts. Their performance relies heavily on the quality of the contacts to the NW, which should exhibit ohmic behavior with low resistance and should be formed in a reproducible manner. In the case of heterostructure NWs for high-mobility applications that host a two-dimensional electron gas, ohmic contacts are particularly challenging to implement since the NW core constituting the conduction channel is away from the NW surface. We investigated contact formation to modulation-doped GaAs/(Al,Ga)As core/shell NWs using scanning transmission electron microscopy, energy dispersive x-ray spectroscopy and electron tomography to correlate microstructure, diffusion profile and chemical composition of the NW contact region with the current–voltage (I–V) characteristics of the contacted NWs. Our results illustrate how diffusion, alloying and phase formation processes essential to the effective formation of ohmic contacts are more intricate than in planar layers, leading to reproducibility challenges even when the processing conditions are the same. We demonstrate that the NW geometry plays a crucial role in the creation of good contacts. Both ohmic and rectifying contacts were obtained under nominally identical processing conditions. Furthermore, the presence of Ge in the NW core, in the absence of Au and Ni, was found as the key factor leading to ohmic contacts. The analysis contributes to the current understanding of ohmic contact formation to heterostructure core/shell NWs offering pathways to enhance the reproducibility and further optimization of such NW contacts.

Fast computational approach with prior dimension reduction for three-dimensional chemical component analysis using CT data of spectral imaging.

Spectral image (SI) measurement techniques, such as X-ray absorption fine structure (XAFS) imaging and scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS) or electron energy loss spectroscopy (EELS), are useful for identifying chemical structures in composite materials. Machine-learning techniques have been developed for automatic analysis of SI data, and their usefulness has been proven. Recently, an extended measurement technique combining SI with a computed tomography (CT) technique (CT-SI), such as CT-XAFS and STEM-EDS/EELS tomography, was developed to identify the three-dimensional (3D) structures of chemical components. CT-SI analysis can be conducted by combining CT reconstruction algorithms and chemical component analysis based on machine learning techniques. However, this analysis incurs high computational costs owing to the size of the CT-SI datasets. To address this problem, this study proposed a fast computational approach for 3D chemical component analysis in an unsupervised learning setting. The primary idea for reducing the computational cost involved compressing the CT-SI data prior to CT computation and performing 3D reconstruction and chemical component analysis on the compressed data. The proposed approach significantly reduced the computational cost without losing information about the 3D structure and chemical components. We experimentally evaluated the proposed approach using synthetic and real CT-XAFS data, which demonstrated that our approach achieved a significantly faster computational speed than the conventional approach while maintaining analysis performance. As the proposed procedure can be implemented with any CT algorithm, it is expected to accelerate 3D analyses with sparse regularized CT algorithms in noisy and sparse CT-SI datasets.

Low-temperature creep performance of additive manufactured Ti–6Al–4V

Abstract Additive manufacturing enables the fabrication of versatile and cost-effective metallic-alloy components from a digital data model. This study explores the prospects of selective laser melting (SLM), an additive manufacturing technique, for fabricating Ti6Al4V alloy components from Ti6Al4V alloy powders. Selective laser melting parameters, such as laser power, scanning speed, powder thickness, hatching space, and scanning strategy, are carefully selected through a series of experiments. The metallurgical characteristics (microstructure, grain orientation, and phase composition), microhardness, and creep performance of the as-fabricated specimens are tested and analyzed. The kinetics of phase transformation and rupture mechanism are determined using advanced instrumental characterization tools, such as field emission scanning electron microscope, energy dispersive X-ray spectroscope, X-ray diffractometer, and transmission electron microscope.

Experimental investigation of degradation mechanism in proton exchange membrane water electrolyzer under prolonged and severe bubble accumulation condition

Proton exchange membrane water electrolyzer (PEMWE) exhibits significant potential as a technology for hydrogen production driven by sustainable energy sources. In this study, the performance degradation characteristics of PEMWE under severe bubble accumulation condition lasting 100 h were investigated through in-situ and ex-situ characterization techniques. The results show that an increasing performance disparity with higher voltage, notably at lower temperatures, reaching a 58.2 % current density degradation rate at 50 °C and 2.0 V. Electrochemical impedance spectroscopy (EIS) analysis suggests that electrolyzer performance degradation is mainly due to increased charge transfer impedance, especially at the anode. In addition, the degraded electrolyzer exhibits a significant delay in reaching a stable current density during the abrupt voltage loading process, and its Tafel slope and electrochemically active surface area (ECSA) increased and decreased by 12.8 % and 13.5 %, respectively. Based on scanning electron microscopy (SEM) images, post-experiment analysis reveals pronounced thinning and noticeable cracks in both cathode and anode catalyst layers near the outlet, particularly on the anode side. Additionally, energy dispersive spectroscopy (EDS) mappings and transmission electron microscopy (TEM) images confirm substantial Pt/C and IrO2 catalyst particle dissolution, migration, and agglomeration. The findings of this study contribute to enhancing understanding of the performance degradation mechanisms in PEMWE.

In Vivo Investigation of 3D-Printed Calcium Magnesium Phosphate Wedges in Partial Load Defects.

Bone substitutes are ideally biocompatible, osteoconductive, degradable and defect-specific and provide mechanical stability. Magnesium phosphate cements (MPCs) offer high initial stability and faster degradation compared to the well-researched calcium phosphate cements (CPCs). Calcium magnesium phosphate cements (CMPCs) should combine the properties of both and have so far shown promising results. The present study aimed to investigate and compare the degradation and osseointegration behavior of 3D powder-printed wedges of CMPC and MPC in vivo. The wedges were post-treated with phosphoric acid (CMPC) and diammonium hydrogen phosphate (MPC) and implanted in a partially loaded defect model in the proximal rabbit tibia. The evaluation included clinical, in vivo µ-CT and X-ray examinations, histology, energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) for up to 30 weeks. SEM analysis revealed a zone of unreacted material in the MPC, indicating the need to optimize the manufacturing and post-treatment process. However, all materials showed excellent biocompatibility and mechanical stability. After 24 weeks, they were almost completely degraded. The slower degradation rate of the CMPC corresponded more favorably to the bone growth rate compared to the MPC. Due to the promising results of the CMPC in this study, it should be further investigated, for example in defect models with higher load.