SEM Mapping Research Articles

Effect of hot pressing and reinforcement of TiC and WC on the mechanical properties and microstructure of AlCuFeCrNi HEAs alloy

In this study, a powder mixture consisting of TiC (titanium carbide) and WC (tungsten carbide) reinforced AlCuNiFeCr was produced using the hot pressing technique. The AlCuNiFeCr powder mixture, TiC and WC were added at a rate of 5 %, 10 % and 15 %, respectively. In order to produce and control to produce parameters have been produced having automation systems type of laboratory a hot pressing machine. Graphite moulds were used in production and sintering processes were carried out in a protective argon gas atmosphere. Composites were produced at a sintering temperature of 900?C and under a pressure 35 MPa and for 4 minutes. To understand the microstructure and mechanical properties of produced specimens, their SEM and EDS analysis, XRD analysis, fracture surface SEM images, SEM mapping of elemental distribution and EDX spectrums, hardness, three-point bending, and corrosion tests were investigated. As a result, the best sample has been identified that belong to AlCuNiFeCr-15 % WC with great features.

Optimization of surface texture fabricated by three-step microarc oxidation for self-lubricating composite coating of diesel engine piston skirts

A surface texture produced by three-step microarc oxidation (MAO) was optimized to improve the tribology performance of a self-lubricating composite coating for diesel engine piston skirts. WS2 was introduced into the self-lubricating composite coating as a self-lubricating additive. The effects of MAO’s varying electrical parameters in terms of stages and action time on the microstructure and chemical composition of the coatings were analyzed by XPS mapping, micron CT, SEM, XRD, and EDS mapping. Furthermore, friction-wear tests under dry lubricating were employed to evaluate the self-lubricating property of the composite coating. Compared to the bare ZL109 aluminum alloy, the optimized composite coating’s friction coefficients were reduced by 60%. Notably, the wear loss of cylinder liner samples matched with the optimized composite coating was almost zero under this work condition.

Multifunction Sr doped microporous coating on pure magnesium of antibacterial, osteogenic and angiogenic activities

Strontium (Sr) ions were added to porous magnesium (Mg) oxide with silicon and fluorine by microarc oxidation (MAO) to improve its osteogenic and pro-angiogenic properties. First, pure Mg was oxidized by MAO, and Sr was added by electrolysis. The surface of the resulting Sr coating was characterized by SEM, EDS, and EDS mapping. The release of Sr ions was monitored by ICP-OES. The antibacterial property of the coating was assessed against Staphylococcus aureus. The effect of Sr coating on osteogenesis was tested in MC3T3-E1 cell line by performing cell adhesion and proliferation tests, alkaline phosphatase (ALP) activity detection, cell morphology characterization, alizarin red staining, and osteogenic-related gene expression analysis. Finally, HUVECs cells were used to test the effect of Sr coating on angiogenesis through cell migration and tube formation assays, VEGF quantification, chicken embryo chorioallantoic membranes (CAM) test, and angiogenic-related gene expression analysis. The results showed that Sr coating had a hierarchical microstructure with a microporous structure evenly covered with nano-grains and that the Sr elements from the coating were released slowly and continuously. Sr coating had effective antibacterial properties and promoted cell adhesion, proliferation, ALP release, calcium nodule formation, and upregulated osteogenic gene expression. Moreover, the coating could promote migration, tube formation, VEGF expression, and angiogenic gene upregulation in endothelial cells. Sr coating also enhanced angiogenesis of CAM. This study supports that Sr coating on Mg- MAO enhances osteogenesis and angiogenesis.

A Novel Image Processing Technique for Analyzing Wear Worn Surface Roughness and Corrosion Behavior of Sintered Mg/B4C Composites

The pure Mg and Mg-B4C composites are produced with dissimilar weight percentages (Mg-5% B4C, Mg-10% B4C, and Mg-15% B4C) using powder metallurgy methods. To find the consequences of B4C in pure Mg, the Vickers micro-hardness, dry sliding wear, 3D roughness profile, and immersion corrosion tests were conducted. To quantify the texture of the composite surface, the local binary co-occurrence pattern quantification technique was used in this analysis and the related texture features were extracted to evaluate the composite surfaces. The wear analysis of Mg-B4C composites was examined in disparate loads of 30, 60, and 90 N with a constant sliding velocity of 2 m/s and in 2000 m constant sliding distance. The changes in wear rate, wear depth, and friction coefficient were compiled and analyzed. It was identified that the wear rate increased with the increment of load. To comprehend the wear mechanism of pure Mg and all Mg-B4C (5–15%) composites, its worn surfaces were subjected to SEM and EDS mapping analyses. The surface roughness of the worn surfaces was explored using a 3D roughness profile test and atomic force microscopy analysis. The obtained results exhibited that the hardness of Mg-B4C composites increased with increasing of B4C weight percentages. The rate of corrosion was discovered using the weight loss method. The corrosion rate decreased to a great extent with the increasing weight percentage of B4C in the Mg matrix.

P.222 Brain functional correlates of emotional face processing in body dysmorphic disorder

Strontium (Sr) ions were added to porous magnesium (Mg) oxide with silicon and fluorine by microarc oxidation (MAO) to improve its osteogenic and pro-angiogenic properties. First, pure Mg was oxidized by MAO, and Sr was added by electrolysis. The surface of the resulting Sr coating was characterized by SEM, EDS, and EDS mapping. The release of Sr ions was monitored by ICP-OES. The antibacterial property of the coating was assessed against Staphylococcus aureus. The effect of Sr coating on osteogenesis was tested in MC3T3-E1 cell line by performing cell adhesion and proliferation tests, alkaline phosphatase (ALP) activity detection, cell morphology characterization, alizarin red staining, and osteogenic-related gene expression analysis. Finally, HUVECs cells were used to test the effect of Sr coating on angiogenesis through cell migration and tube formation assays, VEGF quantification, chicken embryo chorioallantoic membranes (CAM) test, and angiogenic-related gene expression analysis. The results showed that Sr coating had a hierarchical microstructure with a microporous structure evenly covered with nano-grains and that the Sr elements from the coating were released slowly and continuously. Sr coating had effective antibacterial properties and promoted cell adhesion, proliferation, ALP release, calcium nodule formation, and upregulated osteogenic gene expression. Moreover, the coating could promote migration, tube formation, VEGF expression, and angiogenic gene upregulation in endothelial cells. Sr coating also enhanced angiogenesis of CAM. This study supports that Sr coating on Mg- MAO enhances osteogenesis and angiogenesis.

Production of mixed rare earth oxide powder from a thorium containing complex Bastnasite ore

The production of mixed rare earth oxide powder from a thorium containing bastnasite ore by sulfuric acid bake-water leaching followed by precipitation with oxalic acid and thermal decomposition of the oxalates was investigated. The sulfuric acid baking was performed at 250 °C and the optimum baking time was found to be 3 h. Using deionized water as lixiviant, 92.6% La, 86.8% Ce, 86.9% Pr, 82.3% Nd, 95.4% Th and 31% Y were dissolved from the baked ore at 25 °C after 30 min of leaching. The effect of solid-to-liquid ratio on the dissolution of the rare earth elements and thorium shows that when the solid ratio in the water increased from 1:10 to 1:3, the dissolution percentage decreased. The final mixed rare earth oxide powder contained 88.54% REO and 6% ThO2 together with small amounts of other impurities. The SEM mapping results revealed that the produced REO has an irregular crystal shape. Based on the experimental results obtained from the current study, a flowsheet was proposed for the production of mixed rare earth oxide powder from a specific complex bastnasite ore.

Synthesis and characterization of UTSA-76 metal organic framework containing Lewis basic sites for the liquid-phase adsorption of UVI

UTSA-76 encoded MOF structure containing Lewis basic groups was efficiently synthesized and characterized for the removal of UVI from the liquid phase by using adsorption technique. 1H, 13C-NMR, FT-IR, P-XRD, TEM, TEM-EDX, BET, SEM and SEM-EDX mapping techniques were applied to define this adsorbent material. Adsorption of UVI on the synthesized UTSA-76 structure was investigated depending on the parameters of pH, temperature, mixing time and solution concentrations. In the kinetic of adsorption process, not only the pseudo-second-order kinetic, but also film diffusion was effective. The adsorption equilibrium of UVI on UTSA-76 explained better by Langmuir isotherm model and the qmax from Langmuir isotherm was calculated as 91.31 mg/g. The synthesized MOF structure (UTSA-76) demonstrated a removal rate from 12 ppm to 0.25 ppm in 45 min to a very low UO22+ ion concentration of about 98 % using a low adsorbent mass of 5 mg, and UTSA-76 with this adsorption performance will be among the highly preferred effective adsorbents for uranium adsorption.

Improvement of alumina-based porous body fabricated by freeze casting route via alpha alumina/colloidal silica sol precursors

In this paper, alumina-based porous bodies were fabricated by the freeze casting method, and the effects of solid content and freezing conditions on mechanical properties, water permeability, and microstructure of samples were thoroughly investigated. Microstructural evaluation revealed highly porous microstructures with unidirectionally aligned porosities in the samples. SEM micrographs exhibited uniform pores with an average size of 5 μm. Additionally, EDS analysis and SEM mapping showed a comprehensive interconnected porous framework among alumina particles fabricated by amorphous colloidal silica during the freezing step. Mullite phase was observed in the XRD patterns of the samples after sintering at 1400 °C for 2 h. Maximum compressive strength reached 145 MPa, and this significant mechanical strength was owing to the particle densification caused by the mullitazation reaction between alumina and silica during sintering. Physical properties measurements illustrated the minimum open porosity of 41 vol.% and the maximum bulk density of 2.1 g cm−3. Permeability assessment as an important factor to evaluate filtration efficiency showed at least 0.22 (g. cm−2. s−1.bar−1) water flow rate, which was approximately twice greater than that of other recent works.

Porous vaterite and cubic calcite aggregated calcium carbonate obtained from steamed ammonia liquid waste for Cu2+ heavy metal ions removal by adsorption process

Removal of copper ions (Cu2+) from wastewater has garnered significant interest due to the growing environmental concerns. In order to address such issues, porous vaterite and cubic calcite aggregated CaCO3 is successfully prepared from steamed ammonia liquid waste (CaCl2) and (NH4)2CO3 (Ca2+/CO2−3M ratio = 5) via a simple precipitation method conducted at room temperature. The physicochemical properties of CaCO3 are studied using conventional material characterization techniques. Furthermore, the possible formation mechanism of the as-obtained CaCO3 is also discussed in this work. The effects of the CaCO3 quantity, pH, temperature, reaction duration, and initial Cu2+ solution concentration on the Cu2+ adsorption by CaCO3 are also investigated. A high Cu2+ removal rate, i.e., as high as 99%, is achieved with the use of CaCO3 (1000 mg·L−1). After the adsorption process, the residual Cu2+ concentration is less than 0.5 mg/L (from an initial Cu2+ concentration of 500 mg·L−1), which meets the discharge standard for industrial waste. The adsorption kinetics of the process can be expressed by a pseudo-second-order model, with a R2 of 0.9992. Langmuir adsorption model can be used to express the equilibrium adsorption of the as-prepared CaCO3, with a R2 of 0.9967. The obtained sediment after adsorption process is characterized with XRD, XPS, SEM, SEM-EDS, TEM, TEM-SEAD, EDS, and EDAX elemental mapping. Based on the collective results, Cu2+ removal mechanism by the aggregated CaCO3 in aqueous solution is based on two simultaneous process, i.e., adsorption and ion exchange chemical precipitation.

N-doped honeycomb-like porous carbon derived from biomass as an efficient carbocatalyst for H2S selective oxidation

3D interconnected porous N-doped carbocatalyst derived from the waste air-laid paper plays as an efficient metal-free catalyst for H2S removal in super-Claus reaction. The honeycomb-like porous nitrogen-doped carbons are fabricated through a facile impregnation of alkaline solution and NH3 post-treatment method. The experiments prove that NH3 post-treatment is an efficient way to improve the catalytic performance, which resulting in outstanding reactivity and stability with highest sulfur formation rate of 496.6 gsulfurkgcat.−1 h−1 and sulfur yield of 86.7 % in feed gas with high concentration (ca. 10,000 ppm) of H2S for selective oxidation. Significantly, the optimized pyridinic-N content and defect degree endow the N-doped porous carbon (NPC700) with highest catalytic activity according to the Raman and XPS results. The high surface area and abundant porous structure also contribute to the high catalytic performance by increasing the exposure degree of active site and offering additional active surface. Based on the XPS, SEM, TEM and EDS mapping results, the N-doped porous carbon are proved to be stable catalysts since the morphology and surface chemical environment remain similar after the oxidative desulfurization process.

Effect of anion exchange ionomer content on electrode performance in AEM water electrolysis

Anion exchange membrane water electrolysis (AEMWE) has acquired substantial consideration as a cost-effective hydrogen production technology. The anion ionomer content in the catalyst layers during hydrogen and oxygen evolution reaction (HER and OER) is of ultimate significance. Herein, an in-situ half-cell analysis with reference electrodes was carried out for simultaneous potential measurements and identification of the influence of the anion exchange ionomer (AEI) content on anode and cathode performance. The measured half-cell potentials proved the influence of AEI content on the catalytic activity of HER and OER, which was supported by the rotating disk electrode (RDE) measurements. Cathode overpotential of Ni/C was not negligible and more affected by the AEI content than anode with the optimized AEI content of 10 wt% while NiO anode OER overpotential was independent of the AEI content. For the same AEI content, PGM catalysts showed higher electroactivity than Ni-based catalysts for HER and OER and the cathode catalyst's intrinsic activity is of high importance in the AEM electrolysis operation. Post-mortem analysis by SEM mapping of both AEI and catalyst distributions on the electrode surface showed the effect of AEI loading on the catalyst morphology, which could be related to the electrode performance.

Synthesis and characterization of electrospun cerium-doped bioactive glass/chitosan/polyethylene oxide composite scaffolds for tissue engineering applications

In this study, a series of electrospun chitosan/polyethylene oxide (PEO) nanofibrous scaffolds containing different amount of cerium-doped bioactive glasses (Ce-BGs) have been fabricated and proposed for tissue engineering applications. On a biological level, higher 8Ce-BG content significantly improved cytocompatibility of the scaffolds. Moreover, results of fibroblast cell culture study showed that greater 8Ce-BG content could enhance cell attachment and cell expansion on fiber mesh. Characterization of the scaffolds revealed that increasing 8Ce-BG content caused bioactive glass nanoparticles to agglomerate at a higher rate. The SEM mapping revealed thorough dispersion of submicrometric clusters in all areas of the polymeric matrix. Contact angle measurements showed that increasing 8Ce-BG/CH ratio from 0 to 10 (wt.%) improved wettability of the scaffold significantly. However, by increasing the ratio beyond 10 (wt.%), the wettability values decreased gradually. In conclusion, it was found that increasing 8Ce-BG/CH weight ratio up to 40 (wt.%) in the scaffold system was practical and useful for soft tissue engineering applications.

Enhancement of adsorption capacity of reduced graphene oxide by sulfonic acid functionalization: Malachite green and Zn (II) uptake

Graphene oxide (GO) was synthesized according to the Hummers' method developed to remove some impurities such as malachite green dye and Zn (II) metal ion from aqueous solutions. However, due to the problem of dispersion in water, graphene oxide surface is generally functionalized or composites are prepared with different materials. For this reason, the produced graphene oxide is functionalized with sulfanilic acid to obtain reduced sulfonated graphene oxide (rGO-SO3H). For the characterization of materials, DR/UV–vis, Raman, FT-IR, SEM and SEM-EDX mapping techniques were used. Also, reduced graphene oxide (rGO) was evaluated as a comparative example in adsorption. Effect of parameters such as pH, initial concentration and temperature on the removal of metal ions and dye was studied. Equilibrium was achieved in 90 min. The highest percentage removal of rGO and rSGO was observed at pH = 7. Equilibrium isotherms are defined using nonlinear Langmuir, Freundlich, Dubinin - Radushkevich (D - R) and Sips adsorption isotherm equations. Maximum adsorption capacities were determined as 588.23 mg g−1 and 1111.11 mg g−1 for malachite green, 166.66 mg g−1 and 322.58 mg g−1 for Zn (II), respectively for rGO and rGO-SO3H. Kinetic experimental results fit well with the pseudo-second order model for both dye and metal ion; coefficients of determination were close to 1. Thermodynamic studies showed that the adsorption was spontaneous and the adsorption processes were controlled by a physical mechanism.

Green Synthesis of Kaolin-Supported Nanoscale Zero-Valent Iron Using Ruellia tuberosa Leaf Extract for Effective Decolorization of Azo Dye Reactive Black 5

Kaolin-supported nanoscale zero-valent iron (K-NZVI) was synthesized via a green synthesis method, in which leaf extract of Ruellia tuberosa was used as a reducing agent. The synthesized K-NZVI was used for decolorization of Reactive Black 5 (RB5), an azo dye widely used in textile industry. The XRD patterns of the K-NZVI particles show the characteristic peaks of Fe0, indicating that Fe0 nanoparticles (NZVI) were successfully synthesized on the kaolin surface. The SEM, TEM images and EDS elemental mapping show that the NZVI particles are well dispersed on the kaolin surface, thus, reducing the extent of NZVI aggregation. Batch experiments for decolorization of RB5 were carried out to investigate the effects of process parameters including solution pH, initial dye concentration and contact time. The results show that high decolorization efficiencies are obtained in acidic pH. Increasing initial dye concentration causes the decolorization efficiency to decrease, whereas increasing contact time results in higher efficiency. Furthermore, after five cycles of reuse of K-NZVI, the decolorization efficiency slightly decreases, indicating high reusability and stability of K-NZVI. The disappearance of the characteristic peaks of RB5 solution recorded by a UV–Vis spectrophotometer indicates cleavage of the azo bonds and, thus, the decomposition of RB5 in the solution. From a kinetic analysis performed at various RB5 concentrations, the decolorization process of RB5 by K-NZVI is well fit by the pseudo-first-order kinetic model.

Colossal dielectric response, relaxation mechanism and multiferroic properties of (Ba1-xSmx)(Ti1-xFex)O3 (0.0 ≤ x ≤ 0.5)

Structural, microstructural, dielectric, multiferroic characteristics and relaxation mechanisms of (Ba1-xSmx)(Ti1-xFex)O3 samples with varrying compositions (x = 0.0–0.5) are reported in the present article. Standard crystal data and the Rietveld refinement results suggest tetragonal structure for all the compositions similar to the pure BaTiO3. SEM, EDX and color mapping are used for the analysis of microstructural, compositional and elemental study. Impedance analysis is carried out using Nyquist plot. Relaxation mechanisms are analyzed from the complex permittivity Cole-Cole plot and the Bode plot. Colossal dielectric constant was observed over a wide temperature range for compositions x = 0.3, 0.4 and 0.5 due to the formation of internal barrier layer capacitors and the ferroelectric-paraelectric transitions of BaTiO3 and magnetic transitions of SmFeO3. The colossal dielectric response of these compositions makes them suitable for potential applications in microelectronic devices such as dynamic random access memory (DRAM) and on-chip capacitors.

Catalytic cobalt phosphide Co2P/carbon nanotube nanocomposite as host material for high performance lithium-sulfur battery cathode

Lithium-sulfur batteries are one of the most promising cathode materials for next-generation lithium-ion batteries, but there are still having some problems, for example, poor electrical conductivity, slow shuttle effect, and slow electrochemical reaction kinetics. In this paper, carbon nanotubes materials with good conductivity are used as the substrate. Co2P with catalytic function is grown on the surface of carbon nanotubes by hydrothermal method as the host material of lithium-sulfur batteries. It is characterized by XRD, SEM, TEM, XPS and element mapping. The results showed that Co2P was successfully synthesized on the surface of carbon nanotubes. The study found that the addition of Co2P can promote the conversion of Li2S6 to Li2S4 and Li2S4 to Li2S2/Li2S, and inhibit the shuttle-through effect, improve the cycle stability of lithium-sulfur batteries, and the initial capacity reaches 1372 mAh/g at a current density of 0.1 C, the coulomb efficiency is above 96% with cycled 200 times at a current density of 0.2 C.

Greener pathway toward the synthesis of lichen-based ZnO@TiO2@SiO2 and Fe3O4@SiO2 nanocomposites and investigation of their biological activities.

A green way is introduced to biosynthesis of ZnO@TiO2@SiO2 and Fe3O4@SiO2 nanocomposites using the bioactive potential of Lecanora muralis (LM) lichen. UV‐Vis spectroscopy and GC–Mass analysis of the lichen show the presence of various bioactive constituents inside the lichen aqueous extract. The XRD, SEM, EDS, and elemental mapping techniques revealed the well fabrication of biosynthesized nanostructures. Also, investigation of antibacterial and antifungal activities of nanostructures demonstrated that green synthesized nanostructures have a very good antibacterial ability against Staphylococcus aureus, Escherichia coli, Pseudomonas spp. and Candida spp. pathogenic bacteria, and fungi but no antifungal activity toward the Aspergillus flavus, Aspergillus niger, and Aspergillus terrus fungi species.

The novel mesoporous NiO/C microspheres as cathode material for alkaline NiO–Zn battery

The novel mesoporous NiO/C microspheres have been synthesized, the process involves the first production of α-Ni(OH)2/C precursors followed by thermal annealing at 400 °C under air. The prepared NiO/C composites were characterized by XRD, XPS, SEM, EDS and element mapping, and the synthesized samples show an ultrahigh discharge capacity of 134 mAh g−1 at 5 A g−1 in NiO–Zn battery. Moreover, the NiO–Zn battery exhibits a good cycling life and capacity retention about 85% after 1000 charge–discharge cycles. All these indicate that the synthesized NiO/C composites may be a good new positive material for alkaline Ni–Zn rechargeable battery.

Microstructure and Thermoelectric Characterization of Composite Nanofiber Webs Derived from Polyacrylonitrile and Sodium Cobalt Oxide Precursors

We report the microstructure and thermoelectric properties of composite nanofiber webs, which were fabricated by dual-electrospinning of polyacrylonitrile (PAN) and sodium cobalt oxide (NaCo2O4) precursor solutions with different input compositions and following heat-treatment at 600–900 °C for simultaneous carbonation and calcination. The SEM and EDS mapping images revealed that PAN-derived carbon nanofibers (CNFs) and NaCo2O4-based ceramic nanofibers coexisted in the composite nanofiber webs and that their relative contents could be controlled by the input compositions. The Seebeck coefficient increased from ~26.77 to ~73.28 μV/K and from ~14.83 to ~40.56 μV/K with increasing the relative content of NaCo2O4 nanofibers in the composite nanofiber webs fabricated at 700 and 800 °C, respectively. On the other hand, the electrical conductivity of the composite nanofiber webs increased with the decrement of the relative content of NaCo2O4 nanofibers as well as the increment of the heat-treatment temperature. Owing to the opposite contributions of NaCo2O4 nanofibers and CNFs to the Seebeck coefficient, electrical conductivity and thermal conductivity, a maximum power factor of ~5.79 μW/mK2 and a figure of merit of ~0.01 were attained for CNF/NaCo2O4-based composite nanofiber webs fabricated at 45 wt% input composition of NaCo2O4 and at heat-treatment of 700 °C.

Impact of Se doping on optical and third-order nonlinear optical properties of spray pyrolysis fabricated CdS thin films for optoelectronics

Cadmium sulphide is known to have tremendous applications towards optoelectronic and nonlinear devices. Hence, here we have facilely casted the CdS films with diverse Se contents through low-cost spray pyrolysis technique. XRD study defends mono-phase formation of CdS having hexagonal system at all Se doping contents. Scherrer equation was employed to evaluate crystallite size in range of 15–25 nm. Vibrational study reveals the presence of fundamental modes of vibration of hexagonal CdS. EDX and SEM mapping studies approve the existence of Se and its homogeneous distribution all over the film. SEM micrographs shows the nanoscale grains formation on film surface and the size is increasing with Se doping. Optical study revealed that the grown films are of optimal quality with transparency in range of 60–75% with low absorbance and reflectance values. The refractive index values are noted to varied from 1 to 2.7 with wavelength and noticed to be reduced on Se content in UV–Vis region. The reduction in direct and indirect energy gap was found from 2.46 to 2.34 eV and 2.21 to 1.96 eV, correspondingly due to Se. PL emission profile contains an emission band at 528, 529, 529, 530 and 546 nm for 0.0, 0.5, 1.0, 2.5, 5.0 wt% Se:CdS films. Dielectric constant and loss were estimated. The nonlinear refraction (n2) and absorption coefficient (β) and third-order nonlinear susceptibility $$(\chi^{3} )$$ values were determined using Z-scan and observed in order of 10–8 cm2/W, 10–4 cm/W and 10–3 esu, correspondingly. The high values of $$\chi^{3}$$ propose the films for nonlinear applications.