Energy Dispersive Electron Probe Microanalysis Research Articles

Research into phosphate mineral composition and waste phosphorite ore

Purpose. Theoretical and experimental studies of chemical and mineral composition and the structure peculiarities of phosphorites from Ukrainian deposits to define the degree of their suitability for other industries. Methods. The ore chemical composition was determined by conventional (wet) analysis using standard certified chemical reagents. The mineral composition was studied on the scanning electron microscope equipped with the attachment for the energy-dispersive electron microprobe analysis (EMPA) with the software for calculating the chemical composition of the studied sample microvolume. The petrographic analysis was carried out by the traditional methods of microscopic section preparation with subsequent identification and description of the minerals. The microscopic study of the original ore samples aimed at their mineral composition determination was conducted on the Nu optical microscope (Germany) both in transmitted and reflected light. The thin and polished sections prepared using the standard technology were used as samples. In the laboratory environment, the phosphorites were subjected to magnetic dressing in magnetic fields with different intensity. The experiments in the weak field were modelled with the help of the magnetic analyzer while the experiments in the strong magnetic field were modelled on the rotor separator. The flotation dressing method was studied on the laboratory mechanical flotation machine. Findings. It was found that phosphate nodules are rounded mineral formations of irregular shape; they consist of sand bound with the yellow-brown phosphate cement. Ore useful substance is a phosphorus-bearing mineral that by the element chemical composition corresponds to fluorocarbon-hydroxyl-apatite with the dominant content of Ca (45.23%), P (15.67%), and B (27.87%). The results of the integrated petrographic study of the phosphorite samples from the ore body of “Peremoha” area are presented. Originality.The study has revealed that phosphorus-containing substance in the phosphorite samples is the mass that cements barren minerals (mainly quartz, glauconite, calcite and plagioclase). Practical implications. According to the phosphate content level, the phosphorites from Malokamyshevatske, Iziumske and Sinichino-Yaremovske deposits can be treated as minerals for ferrophosphorus smelting. Keywords: ferrophosphorus, ore substance, phosphorite, mineral varieties, petrography, apatite

Multi-Criteria Assessment of Physical Properties of Nanostructured Decorative Protective Coatings

One of the most efficient methods of improving the durability of a product is applying different coatings to the working surface. The quality of decorative and protective coatings is determined by the quality of workpiece surface (roughness, texture, etc.), preparation of workpiece surface (contamination, presence of oxide films, degree of surface activation by ion etching), and the production methods. The article presents the results of a series of experiments in creating multi-component ion-plasma coatings by vacuum deposition on Ti-Al basis. A series of experiments aimed at obtaining single-layer coatings have been carried out using a certain pattern of sputtering in argon and nitrogen environment. The obtained coatings can have a wide variety of colors. Different properties of the created coatings including spectral characteristics, reflection coefficient at different angles of incidence of light as well as chemical composition have been studied. The energy-dispersive electron microprobe analysis revealed the dependence of coating reflection coefficient and spectral characteristics on the chemical composition.

Homogenization Processes in Single-Crystal and Granular ZhS32-VI High-Temperature Alloys

The microstructure, the segregation of alloying elements, and the diffusion processes in the ZhS32-VI nickel superalloys fabricated by single-crystal casting and argon gas atomization followed by vacuum heat treatment are studied by scanning electron microscopy and energy dispersive electron-probe microanalysis. It is found that vacuum heat treatment at 1280°C of ZhS32-VI alloy granules without the application of external pressure can be used to fabricate a homogeneous alloy with a polycrystalline structure and a grain size of 10–30 μm. The microporosity in this alloy is no higher than that in cast nickel superalloys.

Medieval Gilding Technology of Historical Metal Threads Revealed by Electron Optical and Micro-Raman Spectroscopic Study of Focused Ion Beam-Milled Cross Sections.

Although gilt silver threads were widely used for decorating historical textiles, their manufacturing techniques have been elusive for centuries. Contemporary written sources give only limited, sometimes ambiguous information, and detailed cross-sectional study of the microscale soft noble metal objects has been hindered by sample preparation. In this work, to give a thorough characterization of historical gilt silver threads, nano- and microscale textural, chemical, and structural data on cross sections, prepared by focused ion beam milling, were collected, using various electron-optical methods (high-resolution scanning electron microscopy (SEM), wavelength-dispersive electron probe microanalysis (EPMA), electron backscattered diffraction (EBSD) combined with energy-dispersive electron probe microanalysis (EDX), transmission electron microscopy (TEM) combined with EDX, and micro-Raman spectroscopy. The thickness of the gold coating varied between 70-400 nm. Data reveal nano- and microscale metallurgy-related, gilding-related and corrosion-related inhomogeneities in the silver base. These inhomogeneities account for the limitations of surface analysis when tracking gilding methods of historical metal threads, and explain why chemical information has to be connected to 3D texture on submicrometre scale. The geometry and chemical composition (lack of mercury, copper) of the gold/silver interface prove that the ancient gilding technology was diffusion bonding. The observed differences in the copper content of the silver base of the different thread types suggest intentional technological choice. Among the examined textiles of different ages (13th-17th centuries) and provenances narrow technological variation has been found.

The structure and phase composition of hard alloys of the Cr3C2-Ti system produced by explosive compacting of powders

The work presents the findings of theoretical and experimental studies by scanning electron microscopy and energy-dispersive electron microprobe analysis of the phase composition of hard alloys produced by explosive compacting of the powders of chromium carbide Cr3C2 with titanium. It was found that when the powder mixture is heated in shock waves to 660 °C, the phase composition of hard alloys corresponds to that of the initial components of the powder mixture. With the increasing intensity of the explosive compacting, formation of secondary carbides is observed on the border of the initial components. A further increase in temperature results in a local melting and formation of new fine phases. With the subsequent temperature rise in the shock waves, a transition to the calculated equilibrium composition is observed.

INFLUENCE OF THE TEMPERATURE OF A ZINC MELT ON THE COATING THICKNESS AND STRUCTURE DURING HIGH-TEMPERATURE ZINCPLATING STEELS WITH A HIGH SILICON CONTENT

The experimental results on the fabrication of zinc coatings during high-temperature hot-dip zinc-plating the samples made of steel 09G2S are presented. Coating microstructure and phase composition are investigated by scanning electron microscopy and energy dispersive electron probe microanalysis. It is established that the coating thickness decreases at zinc-plating temperatures of 535–565 °C and reaches the minimum at 555 °C. The ratio of phases in coating at various temperatures is analyzed. It is noted that the coating thickness is minimal when its phase composition does not contain pure ζ-phase. Recommendations for selecting the process temperature of steel with a high silicon content are given.

Measurement of Atomic Fractions in Cu(In,Ga)Se2 Films by Auger Electron Spectroscopy (AES) and Energy Dispersive Electron Probe Microanalysis (ED-EPMA)

Measurement of Atomic Fractions in Cu(In,Ga)Se2 Films by Auger Electron Spectroscopy (AES) and Energy Dispersive Electron Probe Microanalysis (ED-EPMA)

Structure and luminescence of gadolinium-doped cubic boron nitride powder

The structural characteristics and chemical, morphological, and optical properties of cBN and cBN:Gd micropowders are studied by x-ray diffraction, energy-dispersive electron probe microanalysis (x-ray spectral microanalysis), and photoluminescence techniques. Cubic boron nitride (cBN) micropowders were synthesized at high pressures and temperatures from hexagonal boron nitride (hBN) micropowder and Li3N catalyst. cBN:Gd micropowders were synthesized from mixtures of hBN, Li3N, and GdF3 micropowders. A lattice parameter of a~3.615 A is calculated for both types of powder (cBN and cBN:Gd). The photoluminescence spectra of the cBN:Gd powder are found to contain emission lines attributable to intracenter optical transitions of Gd3+ ions.

Energy dispersive electron probe microanalysis (ED‐EPMA) of elemental composition and thickness of Fe‐Ni alloy films

The elemental composition of thin Fe‐Ni alloy films deposited on silicon substrates were determined by electron probe microanalysis with an energy dispersive spectrometer using the STRATAGem software. The work was part of ample inter‐laboratory comparisons organized in the frame of CCQM/SAWG (Consultative Committee for Amount of Substance/Surface Analysis Working Group). Therefore, the evaluation of the measurement uncertainties is treated in detail. By having the mass coverage and estimating a layer density, the layer thickness could be derived. Copyright © 2012 John Wiley & Sons, Ltd.

Nondestructive analysis of single crystals of selenide spinels by X-ray spectrometry techniques

The paper presents possibilities and difficulties in nondestructive analysis of small multielement single crystals performed by means of X-ray spectrometry techniques: micro-X-ray fluorescence spectrometry (μ-XRF), energy-dispersive electron probe microanalysis (ED-EPMA), and X-ray photoelectron spectroscopy (XPS). The capability of the X-ray spectroscopy techniques in elemental analysis is demonstrated with the single crystals of selenide spinels of the general formula MxNyCrzSe4 (M+2 and N+3 are, for example, Zn+2, V+3, Ga+3, Cd+2, In+3, and Sb+3). The results of the nondestructive analyses (μ-XRF, ED-EPMA, and XPS) are compared with those obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) and wavelength-dispersive X-ray spectrometry (WDXRF) following sample digestion. The present study shows satisfactory agreement between the results of μ-XRF analysis performed using the standardless fundamental parameter method and the results obtained with the WDXRF and ICP-OES analyses. If the measured single crystal is precisely positioned, the difference between μ-XRF and wet analysis (WDXRF and ICP-OES) does not exceed 5% rel. The reliable results of ED-EPMA can be obtained only if the measured area is sufficiently large, i.e., of 200 × 300 μm. Even if this condition is fulfilled, the relative difference between the ED-EPMA and the wet analysis may reach 10% rel. In case of the XPS analysis, the accuracy of results depends on the proper preparation of the sample surface. It should be free of contamination that can be obtained by scraping in situ in ultrahigh vacuum. The ion etching, commonly used for cleaning the surface, leads to preferential sputtering; therefore, the reliable results cannot be obtained. FigureThe paper presents possibilities and difficulties in nondestructive analysis of small multielement single crystals performed by means of X-ray spectrometry techniques: micro-XRF, ED-EPMA and XPS.

Fission product release and microstructure changes during laboratory annealing of a very high burn-up fuel specimen

A commercial PWR fuel sample with a local burn-up of about 240MWd/kgHM was annealed in a Knudsen cell mass spectrometer system with a heating rate of 10K/min up to 2750K at which temperature the sample was completely vaporized. The release of fission gases and fission products was studied as a function of temperature. In one of the runs the heating was interrupted successively at 900, 1500 and 1860K and at each step a small fragment of the sample was examined by SEM and analysed by energy dispersive electron probe microanalysis. The release behaviour of volatile, gaseous and other less volatile fission products is presented and analysed with the EFFUS program and related to the structural changes of the fuel.

Combination of Energy Dispersive Electron Probe Microanalysis with X-ray Fluorescence Analysis in a SEM

Combination of Energy Dispersive Electron Probe Microanalysis with X-ray Fluorescence Analysis in a SEM

Wavelength‐ and energy‐dispersive Electron Probe Microanalysis (EPMA) measurements with non‐perpendicular incidence of the electron beam

A database of 416 wavelength- and energy-dispersive EPMA measurements on tilted specimens of NiAl, TiO(2) and Ti(3)Al is presented. The analyses were performed between 10 and 30 kV and the tilt angles were varied between 0 degrees and 60 degrees in seven steps. The necessary hardware modifications for the specimen holder are discussed, as well as the various focusing techniques used in the measurements. A comparison between the experimental data, the calculations of our proza96t program and the results of Monte Carlo simulations shows that up to 50 degrees tilt the predictions of our software are more than satisfactory. At larger tilt angles some deviations become noticeable. The Monte Carlo simulations appear to produce deviations at a somewhat earlier stage already, for reasons as yet unknown.

Multifunctional multi-component PVD coatings for cutting tools

Highly wear resistant PVD coatings are well established in cutting operations. Further efforts to improve the cutting performance need to be focused on all relevant wear mechanisms. Thus, the objectives are an enhancement of the abrasive wear resistance, toughness, oxidation resistance, and reduction of friction. The aim of this work was to investigate properties and cutting performance of new multifunctional multi-component PVD coatings based on Ti 1− x Al x N applied to cutting tools. An industrial cathodic arc-evaporation unit was used to deposit coatings from powder metallurgically produced multi-component targets. Coating structure and chemical composition were characterized using scanning electron microscopy (SEM), energy-dispersive electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Coating hardness and cutting performance were evaluated by Vickers microindentation and cutting tests. The results show a remarkable influence of additional elements on the properties of Ti 1− x Al x N based coatings. Alloying with elements like V, Ta, and B resulted in a significantly increased lifetime in various cutting applications.

The effect of oxide-forming alloying elements on the high temperature wear of a hot work steel

A great deal of research has been conducted to clarify the role of oxide films in the wear of metals. Oxides formed during dry sliding of steels at high temperatures determine their tribological behavior. The present work deals with the influence of the oxide-forming alloying elements aluminum and silicon on the oxidation and wear of three selected hot work steels. For this investigation, ball-on-disc experiments were carried out in ambient air and 500 °C. Wear tracks on the disks and balls were characterized using both a scanning electron microscope and an optical profiler. The oxidation products were characterized using X-ray photoelectron spectroscopy and energy-dispersive electron probe microanalysis. The results show that the alloying elements aluminum and silicon yield a reduction of the oxide film thickness and thus lead to an increase in mechanical wear as temperature rises.

Hydroxylapatite, brushite and ardealite in the bat guano deposit from Pestera Mare de la Meresti, Persani Mountains, Romania

The paper aims to give details on the phosphate association from the Meresti Cave, Persani Mountains, Romania. Ca-phosphates (i.e., hydroxylapatite, brushite and ardealite) are the main components of the guano deposit inside this cave. Associated minerals include gypsum, low quartz, 2M1 illite, interstratified kaolinite-illite, calcite and X-ray amorphous iron sesquioxides. Hydroxylapatite {[Ca 9 . 8 0 4 Mn 0 . 0 0 4 Mg 0 . 0 6 7 Fe 2 + 0 . 0 5 4 K 0 . 0 0 2 Na 0 . 0 0 3 ](P 5 . 9 3 4 S 0 . 0 6 6 )O 2 3 . 9 2 9 (OH) 2 . 0 7 1 } has a = 9.434(3) A, c = 6.868(3) A and V = 529.7(3) A 3 , D x = 3.142 g/cm 3 , D = 3.14(1) g/cm 3 , ω = 1.647(1) and e = 1.641(1). CO 3 bands in the infrared absorption spectrum (ν 3 = 1466 cm - 1 , ν 3 ' = 1430 cm - 1 , ν 2 = 872 cm - 1 ) show that hydroxylapatite from Meresti is carbonate-bearing. Brushite has the mean chemical-structural formula [Ca 0 . 9 8 4 Mn 0 . 0 0 2 Mg 0 . 0 0 9 Fe 2 + 0 . 0 0 4 K 0 . 0 0 1 Na 0 . 0 0 1 ](HPO 4 ) 0 . 9 7 6 (SO 4 ) 0 . 0 2 4 . 2H 2 O. Both unit cell [a = 5.812(5) A, b = 15.169(5) A, c = 6.239(4) A and β = 116.35(13)°] and physical parameters [D = 2.32(1) g/cm 3 , a = 1.540(2), β = 1.546(2), γ c a l c = 1.551, for 2V α = 86°) characterize a term close to stoichiometry. Ardealite has the mean chemical structural formula {[Ca 1 . 9 9 2 Mg 0 . 0 0 4 Fe 2 + 0 . 0 0 2 K 0 . 0 0 1 Na 0 . 0 0 1 ](HPO 4 ) 1 . 0 2 1 (SO 4 ) 0 . 9 7 9 . 4H 2 O]. Its mean unit-cell parameters are a = 5.718(3) A, b = 30.998(24) A, c = 6.248(5) A and β = 117.17(5)°, and the measured physical constants a = 1.529(2), β = 1.537(2), y (calculated for 2V α = 86°) = 1.544, and D = 2.327(3) g/cm 3 . The textural relationships between the three calcium phosphates, observed by scanning electron microscopy and energy-dispersive electron microprobe analysis, suggests that their sequence of crystallization was from hydroxylapatite to brushite and finally ardealite. All the three species clearly resulted from the reaction between the strongly acidic solutions derived from the guano mass and the cave floor or moonmilk flows.

Nickel content of as-received, retrieved, and recycled stainless steel brackets

The purpose of this study was to investigate the composition of as-received, retrieved, and recycled stainless steel brackets. New, used, and recycled brand-matched, slot size-matched, and prescription-matched appliances were subjected to scanning electron microscopy and energy dispersive electron probe microanalysis. Elemental analysis was performed on randomly selected surface bracket base and wing areas, and metal content was statistically analyzed with the 2-way ANOVA and the Tukey test, with treatment (as-received, retrieved, and recycled) and bracket regions (base and wing) serving as discriminating variables (α = 0.05). The results showed that there was no difference in the surface composition of the base; however, surface area-wing analysis indicated that nickel content was decreased in retrieved and recycled specimens, implying that an ionic release effect occurred in vivo. Differences were noted between bracket base and wing with respect to elemental composition for the same brackets, implying that the base and wings are manufactured from different alloys. (Am J Orthod Dentofacial Orthop 2002;122:217-20)

Diffusion-based microalloying of aluminium alloys by powder metallurgy and reaction sintering

A diffusion-based technique of microalloying aluminium powder metallurgy products was examined to expand the range of feasible alloying additions. Thermodynamic calculations and diffusion rates for several elements suggested that tin and silver were the most promising; these elements were successfully alloyed into AA 2014 on both a macroscopic and a microscopic scale. The final microstructures were examined using X-ray diffraction, X-ray mapping and energy-dispersive electron probe microanalysis. Silver additions were homogeneous throughout the alloy microstructure, whereas tin was concentrated in intergranular regions only. The results suggested that the technique was viable for a variety of microalloying elements. Also, the extent of alloying was predicted reasonably well using a mathematical mass balance model.

Quantitative electron probe microanalysis of metallic oxide mixtures applying an empirical calibration technique

An analytical procedure is proposed for the independent quantitative chemical analysis of each element in the presence of other elements in the matrix of a sample by Energy Dispersive Electron Probe Microanalysis. For this purpose, an empirical calibration technique (which we shall call here the JABO method), which studies the variation of the X-ray intensities in terms of the analyte concentration in a chemical system with a complex matrix, is established. The methodology consists of the modification of the unknown sample by addition of a diluent, an internal standard and the analyte itself (dilution-addition method). A mathematical model is proposed to calculate the K parameters for the analyte ( K i) and standard ( K p) in each sample. A series of glass discs for each analyte are prepared which make it possible to obtain experimental values of characteristic X-ray lines. Some new K parameters are defined as K i and K p quotients, which remain constant in a wide concentration range. This allows us to use them for the calculation of the component concentrations of the unknown sample, as reproducing mathematical expressions between X-ray intensity and analyte concentration are obtained. An algorithm is proposed to calculate the component concentration in a sample with a complex matrix where components exist with a strong interelemental interaction effect. The method has been applied satisfactorily to the determination of titanium (accuracy 3%) and zinc (accuracy 0.5%) in the presence of a large proportion of zirconium which acts as interferent.

Melting relations in the system Mg 4Si 4O 12 (En)Mg 3Al 2Si 3O 12 (Py) at high pressures

Melting experiments in the system Mg 4Si 4O 12 (En)Mg 3Al 2Si 3O 12 (Py) have been carried out at 15 and 25 GPa using a uniaxial split-sphere high-pressure apparatus. Quenched melt was identified by textural and compositional observation by scanning electron microscopy and energy dispersive electron probe microanalysis. Melting on the join clinoenstatite-pyrope at 15 GPa is eutectic, and the eutectic temperature at which clinoenstatite (En 99.7Py 0.3), liquid (En 98Py 2), and garnet (En 91Py 9) coexist is 2250°C. The melting temperatures of clinoenstatite and pyrope at 15 GPa are 2350°C and 2275°C, respectively. Consequently, garnet and liquid coexist over a very narrow temperature interval in the range of composition from the eutectic to pyrope. The melting temperature of pyrope at 25 GPa exceeds 3000°C, which is substantially higher than that of MgSiO 3 perovskite. The available data suggest that the melting temperature of perovskite increases with incorporation of Al 2O 3. This is consistent with peritectic melting on the En-Py join at 25 GPa. The wide stability of garnet both in temperature and composition suggests that garnet could be the predominant liquidus phase for ultrabasic bulk compositions up to the pressure at which the perovskite rich in Al 2O 3 is stabilized.