EDS Microanalysis Research Articles

Low-temperature sintering of ceramic bricks from clay, waste glass and sand

In the present work, bricks were made on a real 1:1 scale for the construction of housing. For the preparation of the mixtures, raw materials such as clay, sand and glass obtained from the recycling of brown beer containers were used, applying the method plastic molding for the preparation of the semi-products. It has been established that the addition of sand containing a small amount of montmorillonite to such clay enabled to realization of plastic molding. The incorporation of glass into the clay provided to substantially reduce the sintering time of the bricks up to 8h and to vary their strength properties. Sintering was carried out at 800°C in an air atmosphere. The results of X-ray diffraction (XRD), X-ray fluorescence (XRF) and field emission scanning electron microscopy (FESEM) and EDS microanalysis have shown that the raw materials and ceramic bricks contains quartz and feldspars. Low-temperature sintering has made it possible to obtain high-quality, high-strength building bricks in accordance with standards.

Agate Mineralization in Paleoproterozoic Organic Carbon-Rich Sedimentary Rocks of the Onega Basin (NW Russia): Insights into Genesis

In this contribution, we present the results of mineralogical investigation of the agates in Paleoproterozoic organic carbon-rich sedimentary rocks within the Onega Basin (Fennoscandian shield, Russia) aimed at reconstructing the agate-forming processes. Optical and scanning electron microscopy, EDS microanalysis, thermal analysis, X-ray powder diffraction, Raman spectroscopy, and carbon isotope analysis were used for the study. Three main varieties of agates differing in morphology and texture were identified, including concentrically zoned nodules, fine-banded, and carbon-rich moss agates. Mineralogical evidence indicates the participation of hydrothermal fluids in agate formation. Concentrically zoned nodules could be formed due to the dissolution of carbonate concretions in the organic carbon-rich siltstones and their silicification as a result of late hydrothermal processes. Fine-banded vein agates occur in stockworks crosscutting organic carbon-rich rocks and are widely accompanied by sulfides, selenides, carbonates, sulfates, and iron oxides. Carbonaceous matter in moss agates is present as poorly ordered carbon and is characterized by a low δ13Corg value (−25.64‰), suggesting a biogenic origin. Raman spectroscopy data showed an elevated amount of moganite besides alpha quartz in the concentrically zoned nodules compared to other agate varieties, indicating different ages of the mineralization processes. We suggest that the revealed varieties of agates were formed at different stages of long-term hydrothermal processes occurring in the Onega Basin.

Investigation of Icelandic Dust Presence in the Aerosols Collected at Hornsund (Svalbard, Norwegian Arctic) in Spring 2019

Investigation of Icelandic Dust Presence in the Aerosols Collected at Hornsund (Svalbard, Norwegian Arctic) in Spring 2019

Assessment of hydrological, geological, and biological parameters of a river basin impacted by old Hg mining in NW Spain

Mercury (Hg) is a toxic metal that can cause adverse effects for the health of ecosystems. The Caudal River is one of the main rivers in the Asturias region (NW Spain), whose basin is highly anthropized, hosting several Hg mines, closed in the last century. Arsenic (As) is also found in the mineral paragenesis of the Hg deposits, posing a greater environmental risk. In the mining sites, remaining old facilities and tailings continue to release these elements into the environment. In this work, samples of fluvial sediments and water were taken, both in areas affected by anthropic activity and in pristine areas, in order to establish the background levels for the critical elements. The mineralogical study of the sediments, combined with EDS microanalysis, is useful to identify mineralogical traps such as Fe oxides or clays to retain the As. The As content in all sampled sediments is above the threshold effect levels (TEL), the possible effect range within which adverse effects occasionally occur, according to the Canadian Sediment Quality Guidelines for the Protection of Aquatic Life. This fact is related to a naturally high geochemical background in the basin, due to the existing mineral deposits. The PEL threshold (the probable effect range within which adverse effects frequently occur) is exceeded by more than an order of magnitude in the sediments downstream of the Hg mines. In these points, the As content in the water, exceeding 700 μg L−1 As, is also above the quality standard established in Spanish legislation. As a result, the Caudal River tributaries in the lower part of the basin do not reach a good ecological state, according to the Hydrological Planning Office, and in some cases their state is deficient, showing low richness and high dominance of macroinvertebrates. Although the concentrations decrease with distance from the source, these findings justify the low ecological quality of the affected watercourses.

Analysis of Cracks of Thermostats Casings Made of Brass

As part of the project “Thermostat for universal use in (electro) mobility”, an analysis of three currently used thermostats failed during operation was performed. In all three cases, cracks occurred in the brass outer casings. The cracks were open and fractographical observation was performed. The microstructure of the material was evaluated using both the light and scanning electron microscopy. The local composition of the material was determined by EDS microanalysis. Furthermore, hardness profiles were measured. The cracks were predominantly intergranular with a smaller portion of transgranular cleavage. The microstructure was formed by a mixture of α- and β-phase grains and lead particles. In addition to the stress caused by the overpressure of the molten wax, a higher level of residual stresses caused by deformations can be expected. The failure was caused by the mechanism of stress-corrosion cracking. Metal induced embrittlement or/and corrosion fatigue could interact too.

Identification of Fe-bearing phases in the as-cast microstructure of AA6026 alloy and their evolution during homogenization treatment

The Fe-bearing intermetallic phases present in the as-cast AA6026 alloy and their evolution during homogenization treatments at 480-550?C were investigated using optical microscopy, SEM, and TEM techniques in combination with EDS analysis. In addition to the ?-Al(Fe,Mn)Si phase with dendritic morphology, two types of plate-like Fe-bearing microconstituents were revealed in the microstructure of the as-cast alloy. The EDS microanalysis and electron diffraction showed that one set of platelets represented thin sections of ?-Al(Fe,Mn)Si microconstituent. The other set of plate-like microconstituents was identified as a tetragonal, silicon-rich ?-Al4(Fe,Mn)Si2 phase. The formation of the ?-Al4(Fe,Mn)Si2 phase was attributed to the chemical composition of the alloy. During homogenization, the metastable ?-Al4(Fe,Mn)Si2 transformed into the ?-Al(Fe,Mn)Si phase and fragmented. The dendritic ?-Al(Fe,Mn)Si microconstituents underwent fragmentation. However, while the ?-Al(Fe,Mn)Si microconstituents preserved a b.c.c. crystal lattice throughout the process, the product of the transformation of the ?-Al4(Fe,Mn)Si2 phase exhibited primitive cubic lattice.

Agates from Mesoproterozoic Volcanics (Pasha–Ladoga Basin, NW Russia): Characteristics and Proposed Origin

Agate gemstones occurring in the Mesoproterozoic volcanic rocks of the Priozersk Formation (PrF) within the Pasha–Ladoga Basin (Fennoscandian Shield, NW Russia) were investigated to characterize the mineral and geochemical composition of the agates and provide new information concerning their origin. Optical and scanning electron microscopy, EDS microanalysis, X-ray powder diffraction, X-ray fluorescence spectrometry, Raman spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), and C-O isotope analysis were used for the study. Agate mineralization appears mostly as an infill of fissures, cavities, gas vesicles in massive and vesicular basalts, lava-breccias. The mineral composition of agates is dominated by alpha-quartz (fibrous chalcedony, microcrystalline and macrocrystalline quartz), but it also displays abundances of calcite. The characteristic red-brownish agate’s coloration is caused by multiple hematite inclusions distributed in an agate matrix. The study revealed the two phases of agate formation in the PrF volcanics, which are most likely controlled by two distinctly different fluids and/or their mixture. At first, agates appeared due to post-magmatic iron-rich fluids. The late hydrothermal activity was probably triggered by intrusion of gabbro-dolerite sill and resulted in the second phase of agate formation. We suggest that the late hydrothermal fluids remobilized the iron compounds from the crust of weathering underlying the PrF volcanics, which led to additional formation of vein agates and filling of gas vesicles with hematite-rich calcite/silica matter.

Determination of twist drill bits wear: the effect of the composition and structure of the steels

Abstract The aim of the study was to relate the influence of the chemical composition, structure, and basic properties as hardness of the tested drill bits on resistance to their wear. The chemical composition of the drill bit was investigated using the electric excitation emission spectrometry method and EDS microanalysis. Metallographic specimens were prepared and observed to determine the structure of each tool. Hardness tests were carried out on the shank and the working part of the tools. Material wear tests were carried out on the basis of measuring the wear of the drill bit flank. It has been shown that the appropriate selection of the chemical composition and heat treatment has a significant impact on the wear resistance of cutting tools, which directly translates into their quality.

Antifouling Mortars for Underwater Restoration.

This research has focused on the assessment of the compositional features and mechanical and antifouling performances of two different mortars formulated for an underwater setting, and which contain Mg(OH)2 as an antifouling agent. Regarding the mechanical characterization, the uniaxial compressive strength and flexural strength were measured. The composition of the materials was explored by differential thermal/thermogravimetric analysis (DTA-TG), X-ray diffraction analysis (XRPD), and scanning electronic microscopy (SEM) coupled with EDS microanalysis. The assessment of the biological colonization was evaluated with colorimetric analysis and image analysis. The results suggest that both mortars have good mechanical resistance once set underwater. Moreover, the adding of Mg(OH)2 improves the resistance toward biofouling; this was observed both in laboratory and sea-exposed specimens.

Characterization of micaceous minerals occurring in phosphate ores in Brazil: emphasis on the interstratified phyllosilicates

Micaceous minerals were characterized in three phosphatic ores from mines in Western Minas Gerais State, Brazil, all having complex chemical and mineralogical compositions, with emphasis on interstratified phyllosilicates. Knowledge of the relationship between the physical and chemical characteristics of the phyllosilicates contributed to a better understanding of the physicochemical processes in the mineral processing stages. Characterization of the minerals was carried out mainly by X-ray diffractometry (XRD), which allowed identifying vermiculite and three interstratified phyllosilicate phases. These minerals presented regular stratification of the unit cell, with different percentages of vermiculite and mica. Complementary studies by scanning electron microscopy (SEM) with EDS microanalysis, thermogravimetry and chemical analysis confirmed the identifications by XRD.

Production of Amorphous Silicon Dioxide Derived from Aluminum Fluoride Industrial Waste and Consideration of the Possibility of Its Use as Al2O3-SiO2 Catalyst Supports

This paper presents the results of the study on the development of a methodology for the production of pure amorphous silicon dioxide containing up to 99.8 wt.% of SiO2. As a starting material, a silica gel with a moisture content of up to 55 wt.% and an SiO2/AlF3 ratio of 4 was used. The silica gel was purified using alkaline and acidic solutions in concentrations ranging from 0.1 to 25 wt.%. The analysis of the experimental data allowed to identify the most suitable purification parameters of the starting material. The initial silica gel and the reaction products were studied using the methods of X-ray fluorescence, X-ray phase analysis, electron scanning microscopy, EDS microanalysis, and particle-size analysis. Amorphous silicon dioxide obtained according to the methodology developed by the authors forms agglomerates of spherical silicon dioxide particles up to 1 μm in size. Amorphous silicon dioxide was involved in the preparation of catalyst supports in order to consider the possibility of replacing part of the expensive raw material in the form of aluminum hydroxide. In the work, the characteristics of the addition of this amorphous silicon dioxide and the supports obtained from the traditionally used raw materials were evaluated.

Determination of properties of clean coal technology post-process residue

This article presents the possibilities of using modern measuring devices to determine the properties of process residues (Polish acronym: UPP). UPP was taken from the combustion process from a power plant in Silesia. Determining the properties of UPP is the basis for making decisions about its practical application, for example, as a raw material to obtain useful products such as: pozzolan, cenosphere or zeolite, for which there is demand. The development of advanced technology and science has given rise to modern and precise research tools that contribute to the development of appropriate methods to assess the properties of post-process residue. For this study the following were used: scanning electron microscope with EDS microanalysis and an analyzer for particle size-, shape- and number- analysis. The study conducted confirms the effectiveness of SEM analysis to determine the properties of post-process residue from Clean Coal Technologies (CCT). The results obtained are an introduction to further research on the determination of properties of CCT post-process residue. Research to determine the properties of CCT post-process residue only began relatively recently.

F/OH ratio in a rare fluorine-poor blue topaz from Padre Para\xedso (Minas Gerais, Brazil) to unravel topaz\u2019s ambient of formation

Topaz [Al2SiO4(F,OH)2] is one of the main fluorine-bearing silicates occurring in environments where variably acidic (F)/aqueous (OH) fluids saturate the silicate system. In this work we fully characterized blue topaz from Padre Paraíso (Minas Gerais, Brazil) by means of in situ synchrotron X-Ray and neutron powder diffraction measurements (temperature range 298–1273 K) combined with EDS microanalyses. Understanding the role of OH/F substitution in topaz is important in order to determine the hydrophilicity and the exchange reactions of fluorine by hydroxyl groups, and ultimately to characterize the environmental redox conditions (H2O/F) required for mineral formation. The fluorine content estimated from neutron diffraction data is ~ 1.03 a.f.u (10.34 wt%), in agreement with the chemical data (on average 10.0 wt%). The XOH [OH/(OH + F)] (0.484) is close to the maximum XOH value (0.5), and represents the OH- richest topaz composition so far analysed in the Minas Gerais district. Topaz crystallinity and fluorine content sharply decrease at 1170 K, while mullite phase starts growing. On the basis of this behaviour, we suggest that this temperature may represent the potential initial topaz’s crystallization temperature from supercritical fluids in a pegmatite system. The log(fH2O/fHF)fluid (1.27 (0.06)) is coherent with the fluorine activity calculated for hydrothermal fluids (pegmatitic stage) in equilibrium with the forming mineral (log(fH2O/fHF)fluid = 1.2–6.5) and clearly different from pure magmatic (granitic) residual melts [log(fH2O/fHF)fluid < 1]. The modelled H2O saturated fluids with the F content not exceeding 1 wt% may represent an anomalous water-dominant / fluorine-poor pegmatite lens of the Padre Paraíso Pegmatite Field.

Metallographic Analysis of Stainless Steel Inner Shaft of Centrifugal Pump

The paper focuses on the metallographic analysis of the damaged inner shaft of a centrifugal pump with a magnetic clutch. This pump was used for the pumping of viscous suspensions. The damaged part of the centrifugal pump was made of stainless steel and transmitted power from the magnetic clutch to the impeller of the pump. The pump was overhauled by the Manufacturer after ten years of routine work. Slightly worn parts of the pump, including the inner stainless steel shaft, were replaced by the Manufacturer according to the preserved documentation. The overhauled pump failed after two days of running in the original conditions. The problematic is solved by an analysis of three used inner shafts with the aid of a metallographic analysis of the microstructure of the material, using light microscopy and scanning electron microscopy, and an EDS microanalysis of the chemical composition and hardness measurements.

Rock varnish as a natural canvas for rock art in La Proveedora, northwestern Sonoran Desert (Mexico): Integrating archaeological and geological evidences

Rock surfaces covered with desert varnish frequently feature petroglyphs and thus comprise an important resource for the artistic expression of ancient societies. Knowledge about the processes of varnish formation would be helpful to assess the production, regeneration and durability of this “natural canvas” and related rock art. We performed a multidisciplinary study of rock varnish associated with petroglyphs at the archaeological site of La Proveedora (Sonora, Mexico) that has been occupied by humans for at least 4500 years. An inventory and mapping of these ancient engravings revealed 5873 individual images on 1331 rock surfaces. Classification of these motifs showed that geometric forms were the most commonly featured, followed by zoomorphic and anthropomorphic designs. Colorimetric measurements according to the L*a*b* system confirmed that the carvings have a strong color contrast with the background patina. Petrographic observations revealed the variable thickness of the varnish coating, which penetrates deeper into the granitic rock at contacts with plagioclases and ferromagnesian minerals, forming a “rooted” configuration of the lower boundary. Under SEM thin globular laminae were observed; plagioclase and biotite adjacent to the varnish showed signs of alteration. EDS microanalysis, LIBS and X-ray diffraction demonstrated that the patina consists of Fe and Mn oxihydroxides and clay minerals with differing amounts of Fe and Mn within the coating. These results support the polygenetic model of rock varnish development. Weathering of granite and eolian particles give rise to clay mineral formation, whereas Fe and Mn mobilization and reprecipitation is controlled by microorganisms. Varnish formation was more intensive under moister conditions which prevailed in Sonora during the terminal Pleistocene. Thus, rock varnish comprised a non-renewable resource for ancient artists, being a relict feature. The Holocene rates of patina development were too slow to re-pigment engravings, so the petroglyphs represent a persistent element of a cultural landscape. We attribute the surprising durability of the dark coatings to the “rooted” configuration of their lower boundaries that could be important for petroglyph preservation.

Archaeometric case-study of tiles of different dates from the Royal Monastery of San Lorenzo de El Escorial (Spain)

With the aim to contrast existing historical documentation with information provided by the own materials, an archeometric study of a representative set of tiles from the Monastery of El Escorial was undertaken. The ensemble, composed of 19 ceramic fragments, covers examples from the 16th and 17th century, either from Talavera or Toledo provenances, and was selected according to stylistic criteria. The goals of the study consisted in determining the average chemical composition of the ceramic body, its textural and microstructural characteristics, the crystalline phases to establish firing temperatures, also in studying these aspects in the enamel or glaze layer, as well as in identifying the chromophores for the coloring of the decorations. Conventional techniques such as binocular magnifying glass, XRF spectrometry, petrographic observation by thin-section, XRD, FESEM with EDS microanalysis and visible spectrophotometry were used. Resulting data indicated the use of calcareous clays for the body (22.0–25.5wt.% CaO), the presence of neoformed phases such as gehlenite, diopside and anortite which suggest a firing temperature between 950 and 1050°C approximately, lead-based glazes (∼25.0wt.% PbO on average) with SnO2-opacifier (∼57.0wt.% on average) and Co2+, Cu2+, Fe3+-ions and lead antimoniate for blue, green, brown and yellow decorative colors, respectively.

Ceramic-polymer coatings on Ti-6Al-4V alloy modified with l-cysteine in biomedical applications

Osteoporosis is a 21st century disease that affects an enormous number of people, both sexes, but mainly elderly women. In this work the preparation of ceramic-polymer coatings on titanium alloys, based on poly(ethylene glycol) and poly(ethylene glycol) diacrylate modified with hydroxyapatite and l-cysteine was described. Synthetic hydroxyapatite was obtained by wet chemical synthesis from orthophosphoric acid and calcium hydroxide. It was characterized by FT-IR infrared spectroscopy, X-ray diffractometry as well as the molar ratio Ca/P was determined. For the preparation of composite materials on a polymer matrix, ceramics and l-cysteine were used. The coatings were then characterized by FT-IR spectroscopy to determine the chemical composition. Also the sample morphology was determined using SEM scanning electron microscopy. Subsequently, the obtained coatings were subjected to in vitro immersion tests in artificial saliva and simulated body fluid. After the incubation period, changes in surface morphology were analysed using SEM imaging and EDS microanalysis as well as changes in chemical composition were determined using FT-IR. After the incubation period, changes in surface morphology were analysed using SEM imaging and EDS microanalysis as well as changes in chemical composition were determined using FT-IR. Presented studies enable to state that the applied modifiers support the process of biomineralization by precipitation of apatite skeletons on the surface of coatings.

Mechanical properties of NiCrBSi self-fluxing alloy after LPBF with additional heating

The study was devoted to a detailed experimental study of the implementation conditions of the laser powder bed fusion (LPBF) process of special-purpose products from self-fluxing powdered high-temperature NiCrBSi composite. Optimal regimes of LPBF for the 3D part of the simplest shape were experimentally determined. We recommended laser power P =100 W, the laser scanning velocity is v = 10 cm / s, the beam diameter is 70 μm, process gone in argon. Additional efforts were made to evaluate the effect of additional heating the base platform up to 500 °C. Optical and scanning electron microscopy, the X-ray diffraction analysis and EDS microanalysis were used for describing the sequence of structure formation in the created 3D samples. We conducted mechanical and tribological testing allowed to evaluate the relationship between the laser PBF parameters and data on linear wear, roughness, fracture rupture for 3D from NiCrBSi superalloy after the laser PBF process. Possible causes of increase crack formation during the LPBF of the NiCrBSi powder system are considered and revealed.

The archaeological site of St. Maria Veterana (Triggiano, Southern Italy): Archaeometric study of the wall paintings for the historical reconstruction

This paper focusses on the archaeometric investigation of wall paintings of the St. Maria Veterana archaeological site in Triggiano (Bari, Southern Italy) finalised to support the hypothesis on the historical reconstruction of the site based on iconographic interpretations. The site is an original and relevant example of medieval art in Apulia and in Southern Italy and includes a medieval church surrounded by several additionally architectural elements (chapels, crypts, tombs), nowadays buried below by a Renaissance church. Here, the presence of different pictorial cycles, only partially dated, and the evidence of re-use of painted blocks in Renaissance structures pertaining to medieval structures, suggested a complex scenario in which different artisans and clients were possibly succeeded. The site is also framed in a wider regional context, the Apulian region, currently object of an intense archaeological and scientific debate due to widespread action of valorisation of the cultural patrimony as an essential link between the territory and the cultural identity of the citizens.The study of the site involved the sampling and the analysis of 48 samples of painting fragments, investigated by optical microscopy, scanning electron microscopy with EDS microanalysis (SEM-EDS) and micro-Raman spectroscopy. The obtained results allowed a complete material characterization of mortars and pictorial layers, highlighting the use of precious and rare pigments as cinnabar and verdigris, along with more common recipes based on natural ochres and earths more commonly used in other similar sites through the Apulia region. The combined data obtained from the analysis of mortars and pigments allowed to finally propose a reliable hypothesis on the construction and decorative phases of the site, in agreement with the dating based on iconographic interpretations.Up to now, St. Maria Veterana Church was considered a minor site, mainly due to the scarcity of the written sources. However, the new stylistic interpretation of the pictorial cycles, the preciousness of the used materials, the quality of the manufacture technique and the numerous artistic executive phases identified through five centuries (11th–16th) suggest a continuous attendance of the site by artisans and client carriers of high cultural and artistic values.

Characterisation of a High-Power Impulse Magnetron Sputtered C/Mo/W wear resistant coating by transmission electron microscopy

Thin films of C/Mo/W deposited using combined UBM/HIPIMS sputtering show 2–8 nm clusters of material richer in Mo and W than the matrix (found by EDS microanalysis), with structures that resemble graphitic onions with the metal atoms arranged regularly within them. EELS microanalysis showed the clusters to be rich in W and Mo.As the time averaged power used in the pulsed HIPIMS magnetron was increased, the clusters became more defined, larger, and arranged into layers with amorphous matrix between them. Films deposited with average HIPIMS powers of 4 kW and 6 kW also showed a periodic modulation of the cluster density within the finer layers giving secondary, wider stripes in TEM. By analysing the ratio between the finer and coarser layers, it was found that this meta-layering is related to the substrate rotation in the deposition chamber but in a non-straightforward way. Reasons for this are proposed. The detailed structure of the clusters remains unknown and is the subject of further work.Fluctuation electron microscopy results indicated the presence of crystal planes with the graphite interlayer spacing, crystal planes in hexagonal WC perpendicular to the basal plane, and some plane spacings found in Mo2C. Other peaks in the FEM results suggested symmetry-related starting points for future determination of the structure of the clusters.