EDX Microanalysis Research Articles

Thermoelectric properties of gradient polymer composites with nano-inclusions fabricated by laser assisted sintering

Selective laser sintering (SLS) was used to prepare porous gradient polymer nanocomposites consisting of a polyetheretherketone (PEEK) matrix doped with alternating layers of Ni and Cu nanoparticles. Optimal regimes of such 3D-fabrication were determined. The functional graded (FG) structure of sintered parts was observed by optical and scanning electron microscopy and EDX microanalysis. Temperature dependence of electro-physical properties was studied for alternating ferromagnetic/non-magnetic layers (up to 10 layers) into 3D-graded samples derived from Ni-PEEK-Cu powders. Temperature dependences for the real part of the dielectric permeability and loss tangent were found to have a hysteresis character.

HISTOLOGICAL AND ULTRASTRUCTURAL EFFECT OF ZINC SULPHATE SUPPLEMENTATION ON THE ALVEOLAR BONE OF CALCIUM DEFICIENT RATS

Objective: The aim of the present study was to investigate the efficiency of zinc sulphate supplementation in treatment of the alveolar bone osteoporosis in rats induced by calcium deficient diet.Design: Thirty adult male Wistar rats with an average weight of 200-250 grams were randomized into 3 groups. Group Ι (control group): received standard rat chow, Group ΙΙ (osteoporotic group): received calcium deficient diet and Group ΙΙΙ (zinc treated group): received calcium deficient diet plus oral supplementation of zinc sulphate. After 3 months, the rats were sacrificed. The mandibles were examined histologically, histomorphometrically, ultrastructurally and by energy dispersive X ray microanalysis (EDX). Results: Histologically the impaired bone quality induced by calcium deficiency were significantly improved by zinc supplementation. The alveolar bone restored its structural organization in form of thick bone trabeculae, decrease number of osteoclasts and regularly distributed osteocytes. Histomorphometric analysis showed significant reduction in area percentage of alveolar bone trabeculae in osteoporotic group (p<0.001), while zinc treated group showed significant increase in the area percentage of bone compared to the osteoporotic group (p<0.001). Ultrastructurally, surface roughness and irregularity of the buccal cortical plate were observed in osteoporotic group. However, zinc treated group showed smooth and regular bone surface with minor irregularities. EDX microanalysis indicated a significant decrease in calcium content in osteoporotic group (p<0.001), while zinc treated group showed significant increase in the calcium percentage of bone compared to the osteoporotic group (p<0.001). Conclusions: In a rat model zinc supplementation prevents the bone loss induced by calcium deficient diet.

CoFe2O4-TiO2Hybrid Nanomaterials: Synthesis Approaches Based on the Oil-in-Water Microemulsion Reaction Method

CoFe2O4nanoparticles decorated and wrapped with TiO2nanoparticles have been prepared by mixing well-dispersed CoFe2O4with amorphous TiO2(impregnation approach) and growing amorphous TiO2over the magnetic core (seed approach), respectively, followed by thermal treatment to achieve TiO2crystallinity. Synthesis strategies were based on the oil-in-water microemulsion reaction method. Thermally treated nanomaterials were characterized in terms of structure, morphology, and composition, to confirm hybrid nanoparticles formation and relate with the synthesis approaches; textural, optical, and magnetic properties were evaluated. X-ray diffraction revealed coexistence of cubic spinel-type CoFe2O4and tetragonal anatase TiO2. Electron microscopy images depicted crystalline nanoparticles (sizes below 25 nm), with homogeneous Ti distribution for the hybrid nanoparticles synthesized by seed approach. EDX microanalysis and ICP-AES corroborated established chemical composition. XPS evidenced chemical states, as well as TiO2predominance over CoFe2O4surface. According to BET measurements, the hybrid nanoparticles were mesoporous. UV-Vis spectroscopy showed optical response along the UV-visible light region. Magnetic properties suggested the breaking order of magnetic domains due to modification with TiO2, especially for mediated seed approach sample. The properties of the obtained hybrid nanoparticles were different in comparison with its individual components. The results highlight the usefulness of designed microemulsion approaches for the straightforward synthesis of CoFe2O4-TiO2nanostructured hybrids.

Complementary thermodynamic and dilatometric assessment of phase transformation pathway in new β-stabilized TiAl intermetallics

New Ti-44Al-5Nb-3Cr-1.5Zr(at%) intermetallic alloy, microstructured by float zone (FZ) processing, was subjected to slow dilatometric heating from the room temperature (RT) up to solidus. The evolution of linear thermal expansion coefficient (LTEC) has been compared with the phase transformation path of the alloy within the polythermal section of phase diagram calculated with ThermoCalc®. Thus, the characteristic temperatures of predicted phase transitions were experimentally verified. Results from dilatometry, EDX microanalysis, scanning and transmission electron microscopy have shown that thermodynamic database used is poorly describe the phase transformations in β-stabilized TiAl alloy at the temperatures lower than ~1000°C. While at higher temperatures the perfect correspondence was observed between the ThermoCalc® predictions and dilatometric data. The features of verified phase transformation behavior are discussed in view of comparison with those of “classic” Ti-43.5Al-4Nb-1Mo-0.1B TNM™ alloy. It is assumed that TiAl(Nb, Cr, Zr) alloy is fundamentally more favorable for high-temperature FZ-microstructuring and performance.

RETRACTED: Scanning electron microscopy study of new bone formation following small and large defects preserved with xenografts supplemented with pamidronate—A pilot study in Fox-Hound dogs at 4 and 8 weeks

The aim of the present study was to evaluate the feasibility of SEM and EDX microanalysis on evaluating the effect of porcine xenografts (MP3®) supplemented with pamidronate during socket healing. Mandibular second premolars (P2) and first molars (M1) were extracted from six Beagle dogs. P2 were categorized as small defects (SD) and M1 as large defects (LD). Four random groups were created: SC (small control defects with MP3®), ST (small test defects MP3®+pamidronate), LC (large control defects with MP3®), and LT (large test defects MP3®+pamidronate). At four and eight weeks of healing the samples were evaluated fisically through scanning electron microscopy (SEM), and chemical element mapping was carried out by Energy dispersive X-ray spectroscopy (EDX). After four weeks of healing, SEM and EDX analysis revealed more mineralized bone in ST and LT groups compared with control groups (p<0.05). After eight weeks, Ca/P ratios were slightly higher for small defects (groups SC and ST); in SEM description, in both control and test groups, trabecular bone density was similar to the adjacent mineralized cortical bone. Within the limitations of this experimental study, SEM description and EDX elemental microanalysis have demonstrated to be useful techniques to assess bone remodelling of small and large defects. Both techniques show increased bone formation in test groups (MP3® modified with pamidronate) after four and eight weeks of healing.

Characterization of Zn-Mg-Al Based Drosses from the Continuous Galvanizing

The present paper deals with the microstructure characterization of drosses originated during production of a new type of coating called Zinkomag. This coating creates during continuous galvanizing process and it is characterized by addition of 0.8 - 1.0 wt. % Mg and 0.8 - 1.0 wt. % Al in the zinc galvanizing bath. The addition of magnesium in such coatings leads to increasing of hardness, corrosion resistance, and better color adhesion than most common used coatings (GI coatings). In this paper drosses were investigated using AAS, LM, SEM with EDX microanalysis, and XRD.

Analyzing the surface layer after WEDM depending on the parameters of a machine for the 16MnCr5 steel

Abstract The efficient wire electric discharge machining (WEDM) technology is a trade-off between the cutting speed and the resulting surface quality. A typical morphology of a surface machined using WEDM contains a large number of craters caused by the electric sparks generated in the cutting process. The paper analyzes the influence of the cutting speed on the quantitative and qualitative evaluation of the craters formed on the surface of a workpiece made of the 16MnCr5 steel. Applying metallography to cross-section microscopic slides, diffusion subsurface damages were studied caused by the cutting. The diffusion processes taking place between the electrode and the material machined were studied using a local point EDX microanalysis applied both to the machined surfaces and to the cross sections. A detailed study was also carried out of the brass electrode to measure its wear rate caused by the cutting process as well as its degradation in terms of the quality of its morphology and the chemical composition of surface.

Mechanically Alloyed High Entropy Composite

In the last years high entropy alloys have been investigated due to their high hardness, high temperature stability and unusual properties that make these alloys to have significant interest. In comparison with traditional alloys that are based on two or three major elements, this new generation alloys consists at least of 5 principal elements, with the concentration between 5 and 35 at.%. The present paper reports synthesis of high entropy alloys (HEA) and high entropy composites (HEC) synthesized by mechanical alloying (MA). The equiatomic AlCrFeNiMn matrix was used for creating the HEA matrix, starting from elemental powders and as reinforcing material for composites was used pure graphite. The mechanical alloying process was carried out at different duration, in a high energy planetary ball mill, under argon atmosphere. The elemental powders alloying began after '5 hours of milling and was complete after 40 hours. The mechanical alloyed matrix and composite was pressed and heat treated under argon protection. The elemental powers were investigated for physical - technological properties, and by X-ray diffraction and scanning electron microscopy. Phase pressing operation was realized with a hydraulic press and the applied pressure was progressive. The sintering process was carried out at 850°C for 2 h. The X-ray diffraction revealed that the MA process resulted in solid solutions formation and also revealed body- centred cubic (BCC) and face-centred cubic (FCC) structures with average grain size around 40 nm. In addition, nanoscale particles were highlighted by scanning electron microscopy, as well as the homogeneity of the chemical composition of the matrix and composite that was confirmed by EDX microanalysis. It was noted that HEA matrix and HEA composites were processed with a high degree of compaction and with a quite large capacity of mixed powder densification (around 70%).

N-type single-crystalline Si solar cells: Front side metallization for solar cells reaching 20% efficiency

Screen printed front side contacts were investigated in n-type, high efficiency, single-crystalline Si solar cells with B doped emitters. Cells were processed identically and two different front side pastes were used: paste Ag–Al yielded efficiencies of 20.0%, and paste Ag, without Al, yielded 16.1% efficiency only. Cells contacted with paste Ag–Al yielded a continuous glass layer, a significantly higher density of Ag colloids, and an Al mole fraction of ∼1at%. In contrast, cells contacted with paste Ag revealed a thinner but continuous glass layer as compared to cells processed with paste Ag–Al. It contained a lower density of Ag colloids and Al was below the detection limit of the EDX microanalysis. In n-type cells pyramidal shaped Ag nanocrystals did not appear, whereas for p-type cells they are formed at intersections of differently {111} oriented surface planes at the Si emitter. We did not find Ag/Al spikes at the Si emitter for cells contacted with paste Ag–Al.Cells contacted with paste Ag–Al had a smaller series resistance as well as a significantly lower specific contact resistance (4mΩcm2). A higher series resistance and specific contact resistance >100mΩcm2 was found for cells contacted with paste Ag. It was concluded that the specific contact resistance decreases with increased wetting and increased density of Ag colloids in the glass layer. The series resistance of the Ag–Al alloy contact depended only weakly on temperature, whereas the series resistance linearly increased with temperature for contacts processed with paste Ag.p- and n-type cells with maximum efficiency yield a similar microstructure of the front side contact, similar series and contact resistance, respectively. A high density of Ag colloids in the glass layer was found for cells with low specific contact resistance. This suggests that also for n-type cells a three dimensional percolative charge transport through the glass layer is assisted by the presence of metallic Ag colloids.

Implementation of spectroscopic techniques for characterization of icons of Deir El Sankoria, El Minia, Egypt

Four icons from church of Saint Theodore El Shatby, Deir El Sankoria, El Minia, Egypt, have studied by micro-destructive spectroscopic methods: Attenuated Total Reflection–Fourier Transform Infrared Spectroscopy (ATR–FTIR), Raman Spectroscopy (RS), Field Emission Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy (FESEM–EDX), X-ray Photoelectron Spectroscopy (XPS) and Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP–OES). This study gave information about the materials used in the icons painting, state of the icons, and evaluation of the effect of environmental conditions. ATR–FTIR and Raman methods showed the characteristic bands of lithopone and lead white as a ground material, gum Tragacanth as a binder, and chrome oxide green, mars yellow, mars red as a pigment. EDX microanalysis exhibited the elements of mars yellow and mars red pigments, and ICP–OES method showed the concentration of chromium element that is characteristic for chrome oxide green pigment. The results were authenticated by XPS method to ensure the materials used in the painting. SEM images showed the cracking of the paint surface. Degradation of the chemical structure of gum Tragacanth binder was attributed to metal oxides of the pigments in presence of sunlight and artificial light which led to promotion of the oxidation process and then deterioration of the painting through peeling of the painting surface and cracking of the paint film.

Supported H3PW12O40 for 2-propanol (photo-assisted) catalytic dehydration in gas-solid regime: The role of the support and of the pseudo-liquid phase in the (photo)activity

Catalytic and photocatalytic 2-propanol dehydration was carried out by using a supported Keggin heteropolyacid H3PW12O40 (PW12). Binary materials were prepared by impregnation and/or solvothermal treatment by using commercial supports: SiO2 (Mallinckrodt), TiO2 (Evonik P25) and multiwall carbon nanotubes (Sunnano) or home solvothermically prepared SiO2 and TiO2. All the materials have been characterized by X-ray diffraction (XRD), scanning electron microscopy observations (SEM) coupled with EDX microanalysis, specific surface area measurements, diffuse reflectance spectroscopy (DRS), FTIR and Raman spectroscopy. (Photo)catalytic 2-propanol dehydration was studied in gas-solid regime by using a continuous (photo)reactor working at atmospheric pressure and 80°C. FTIR spectra of the gas-phase over the PW12-support composites, where 2-propanol had been previously adsorbed, were recorded. Propene and diisopropyl ether were the main reaction products. For the continuous photo-assisted runs the reactor was also illuminated with UV light. The apparent activation energy of 2-propanol catalytic and photocatalytic dehydration was determined in the range 60–120°C.The irradiance increased significantly the dehydration reaction rate. Important differences were observed between the different supported materials. The Keggin heteropolyacid species played a key role both for the catalytic and the photo-assisted catalytic reactions; in fact, the acidity of the cluster accounts for the catalytic role, whereas both the acidity of the cluster and the oxidant ability of PW12 were responsible for the increase of the reaction rate of the photo-assisted catalytic reaction. Moreover, the photo-generated electrons on the solid semiconductor conduction band can account for a further increase of the reaction rate, when the heteropolyacid was supported on TiO2. Formation of a pseudo-liquid phase played an important role to determine the (photo)activity.

Microstructural Aspects in FSW and TIG Welding of Cast ZE41A Magnesium Alloy

In this paper, magnesium ZE41A alloy plates were butt joined through friction stir welding (FSW) and Tungsten Inert Gas welding processes. Process-induced microstructures were investigated by optical and SEM observations, EDX microanalysis and microhardness measurements. The effect of a post-welded T5 heat treatment on FSW joints was also assessed. Sound joints were produced by means of both techniques. Different elemental distributions and grain sizes were found, whereas microhardness profiles reflect microstructural changes. Post-welding heat treatment did not induce significant alterations in elemental distribution. The FSW-treated joint showed a more homogeneous hardness profile than the as-welded FSW joint.

High Copper Tolerant &lt;i&gt;P. lilacinum&lt;/i&gt; Strain Isolated from a Rich Environment in Copper, Río Tinto (Sw, Spain)

Río Tinto (Southwestern Spain, Iberian Pyrite Belt) is an unusual extreme environment with an unexpected level of eukaryotic microbial diversity. Of the different fungal strains isolated along the river over several years, one of them,Purpureocillium lilacinumM15001, is able to tolerate up to 1M Cu concentrations. This strain was able to remove 25% of the Cu when incubated at 50mM, 32% at 100mM and 51% at 500mM Cu concentrations. The amount of Cu detected inside the cells increased accordingly the concentration of Cu in the solution, from 8.2% of the total fungal dry weight at 50mM Cu concentration, to 13% when exposed to 100mM Cu and 22.4% at 500mM Cu. TEM studies showed the existence of electrodense material externally adsorbed to the fungal cell wall, as well as large intracellular deposits. EDX microanalyses revealed that this material was composed mainly of Cu. To clarify the possible resistance mechanisms involved in the tolerance of this fungal strain to Cu, a proteomic study has been carried out.

Rhometal interface in pseudo-core shell powders like Permalloy/Rhometal type

The nanocrystalline Ni3Fe (around Permalloy composition) powders were prepared by dry mechanical alloying. The nanocrystalline Ni3Fe and carbonyl Fe mixture powders and green compacts have been subjected to heat treatments in an argon atmosphere in order to obtain pseudo-core-shell like particles by micro-alloying in the temperature range of 400–900°C. The large Permalloy particles are partially covered by very small Fe particles and at the interface a layer of Rhometal is formed by micro-alloying. The Permalloy particles remain in the nanocrystalline/nanostructured state after the annealing independent on the annealing temperature up to 900°C. Structural, microstructural characterisation and local elemental chemical analysis have been performed by X-ray diffraction, scanning electron microscopy and X-ray microanalysis. The Rhometal interface was studied and evidenced by Fe and Ni concentration profile (EDX microanalysis) and X-ray diffraction. It was found that by a heat treatment up to 900°C the interface is in the iron zone and at the heat treatment temperature of 900°C the interface is in both Permalloy and iron zones. By XRD the bcc and fcc structures of the Rhometal have been evidenced. The interface length in iron zones is about 0.8μm for the heat treatment at 400°C and reaches 2.5μm for heat treatment at 900°C. The interface reaches 10μm for a temperature of a heat treatment of 900°C. The iron zones welded by Permalloy zones is evidenced the presence of the Ni atoms up to 4.7at%. Also, in Permalloy particles are evidenced two zones with a different amount of Ni: one around Ni0.6Fe0.4 composition close to the interface and the second in the centre of the Permalloy particle with composition close to Ni3Fe – Ni3−δFe1+δ.

Archaeometry of ferrous artefacts from Luso-Brazilian archaeological sites near Ipanema River, Brazil

AbstractThe present investigation analysed iron artefacts collected in two sites around Araçoaiaba Hill. A known methodology was adapted to investigate several samples collected at the Royal Iron Factory of São João do Ipanema and Sardinha sites. EDX microanalysis results of non-metallic inclusions were plotted in bivariate graphs. Linear regression (with and without the zero-intercept constraint) and line intercept significance tests were applied to interpret these results. The analysis did not allow the identification of the provenance of the production systems of Sardinha and Ipanema sites. The presence of Ti-rich inclusions was an unambiguous attribute of the samples collected at the Sardinha site.

Structure of fluorite-like compound based on Nd₅Mo₃O₁₆ with lead partly substituting for neodymium.

A single crystal of Nd5Mo3O16 with lead partly substituting for neodymium, which has a fluorite-like structure, was studied by precision X-ray diffraction, high-resolution transmission microscopy and EDX microanalysis. The crystal structure is determined in the space group Pn3¯n. It was found that the Pb atoms substitute in part for Nd atoms in the structure and are located in the vicinity of Nd2 positions. Partial substitutions of Mo cations for Nd positions and of Nd for Mo positions in crystals of the Ln5Mo3O16 oxide family are corroborated by X-ray diffraction for the first time. The first experimental verification of the location of an additional oxygen ion in the voids abutting MoO4 tetrahedra was obtained.

Research of Interactions between Al Substrate and Zn-Al Solders

The aim of work consists in the study of interactions on solder/substrate boundary in fluxless soldering of self-hardening Al alloy Al7075. The ZnAl5Mg3 and ZnAl5Cu3 solders were used in experiments. The soldering parameters were as follows: soldering temperature from 350°C to 390°C., acting time of ultrasonic energy 3 to 5 s, ultrasound frequency 20kHz. Soldered joints were assessed by optical light microscopy, EDX microanalysis and XRD analysis. It was found out that the ZnAl5Mg3 solder is composed of β-Zn phase and of eutecticum composed of Mg2Zn11 intermetallic phase. ZnAl5Cu3 solder is composed of β-Zn phase and CuZn5 intermetallic phase in base β-Zn matrix. Due to eutectic reaction between the solder and substrate, strong interaction on boundary was observed. The reaction layer was formed mostly of α(Al)-β(Zn) mixture.

Soldering of Copper with High-temperature Zn-based Solders

The work deals with the study of interaction Cu substrate (purity 5N) and Zn4Al and Zn6Al6Ag (purity 4N) solders for higher application temperatures. Soldering was performed with power ultrasound in the air without flux application at temperature 420°C. Acting time of ultrasonic vibration was 5 s. Soldered joints were assessed by optical light microscopy, EDX microanalysis and DSC analysis. It was found out that the melting temperatures of solders were 404.9°C and 396.9°C. Intermetallic layers (IM) CuZn4 and Cu5Zn8 were formed at the Cu/Zn4Al boundary. At the boundary Cu/Zn6Al6Ag there were formed AgZn3 and Cu5Zn8 IM layers. Shear strength of joint Cu/Zn4Al was 34.5MPa and shear strength of Cu/Zn6Al6Ag was 39MPa.

Disk Laser Welding of ZE 41 Magnesium Alloy

The paper deals with disk laser welding of magnesium alloy with the content of rare earth elements. ZE 41 magnesium alloy with the thickness of 2.0 mm was used as experimental metal. TruDisk 4002 solid state laser with a wavelength of 1.03 microns and a maximum power of 2.0 kW was used for welding of magnesium alloy. Laser power which was applied ranged from 0.6 to 1.2 kW. The focal position of laser beam was fixed on the surface of magnesium alloy and the welding speed was set to 70 mm/s. Argon with flow rate of 12 l/min was used as shielding gas. Light microscopy, EDX microanalysis and micro hardness measurements across base metal - fusion zone interface were carried out in order to analyze the weld joints.

Disk Laser Welding of Copper to Stainless Steel

The paper concerns with welding of copper to stainless steel. Technically pure Cu and AISI 304 austenitic stainless steel with the thickness of 2.0 mm were suggested as experimental metals. TruDisk 8002 laser with the wavelength of 1.03 μm and a maximum power of 8.0 kW was used for production of dissimilar metal welds. Laser power from the range of 2.3 to 2.9 kW and welding speed from 35 to 50 mm/s were used for welding dissimilar metals. Focal position was direct on the surface of welded metals. Helium with flow rate of 17 l/min was used for shielding of molten weld metal. Light microscopy, EDX microanalysis and micro hardness measurements across copper - fusion zone - stainless steel interface were performed in order to study the properties of the weld joints.