EDX Microanalysis Research Articles

Study of Root Transparency in Different Postmortem Intervals Using Scanning Electron Microscopy.

In the fields of forensics, the identification of human remains is a recurrent problem. The estimated age at death is one of the copious criteria to be evaluated. In adult teeth, the height of the root dentin transparency is used to estimate age. However, in archaeological material, this phenomenon appears inconstant. The aim of this work was to observe the structural modifications of the sclerotic dentin in the teeth for different postmortem intervals. The study included two parts (retrospective and prospective study) with 21 human monoradicular teeth, from bodies donated to medical science with postmortem intervals (PMIs) of 0, 1, 2 and 5 years and archeological excavation. After inclusion based on resin, section and polishing, the samples were analyzed with a scanning electron microscope (SEM) JSM-7800F®, and the procedure was completed via a semiquantitative analysis of calcium and phosphorus using EDX microanalysis. The analysis showed the existence of tubular and chemical modifications of sclerotic dentin at different PMIs. Our SEM study allowed us to observe a difference in tubule aspects linked to an increased PMI: the loss of peritubular collar and the lumen obstruction of tubules with a hyperdense material. Microanalysis highlighted variations in phosphocalcic ratios among the different groups, especially in the pulp area and the canine. Our hypotheses that explain these differences are based on the postmortem modifications of the crystals of the mineral phase of sclerotic dentin under the influence of chemical and/or bacterial action.

Glass with a low-melting temperature belonging to the P2O5–CaO–Na2O system, applied as a coating on technical ceramics (alumina, zirconia) and traditional ceramics (porcelain stoneware)

This article investigates the development and potential applications of low-melting point lead-free glasses. Their importance is due to strong market demands to comply with the strict international regulations against the use of lead. In this work, a preliminary study of the existing interactions of a low-melting-temperature glass belonging to the P2O5–CaO–Na2O system when it is deposited on different ceramic substrates, both traditional (porcelain stoneware) and technical (alumina and zirconia), has been carried out. The ionic diffusion through the studied interfaces, the phases present, the composition of the glassy phase and the surface morphology of the coating have been studied by Field Emission Scanning Electron Microscopy (FESEM), with coupled EDX microanalysis. The chemical resistance of the different glassy coatings obtained is also evaluated. The results showed that these new lead-free low-melting-temperature glassy coatings are chemically and mechanically compatible, and promising candidates for applications and markets in a broad range of fields.

Microstructural and Elemental Characterization of Root Canal Sealers Using FTIR, SEM, and EDS Analysis

Background: Root canal sealers and repair materials should have the desirable physical, chemical, and biological characteristics, and an antibacterial effect if possible. There is little information available on the biocompatibility of new sealers on the market. Fourier transform infrared spectroscopy (FTIR) can offer trustworthy data to examine chemical structures; another technique for revealing the elements in the constituents that may contribute to the cytotoxicity of these sealers is scanning electron microscopy (SEM), with the goal of elemental mapping utilizing energy-dispersive X-ray spectroscopy (EDX). Methodology: All the root canal sealers were mixed as per the manufacturers’ instructions and allowed to set in molds for 24 h. Then, the samples were placed into an incubator (Memmert GmbH + Co. KG, Schwabach, Germany for 72 h, in a moist environment to allow complete chemical setting of the sealers. The organic and inorganic components of the sample were identified using FTIR with the wavelength length in the infra-red region measuring 400–450 nm. The finely crushed samples were coated with gold metal; following that, the sealer samples were examined under a scanning electron microscope (SEM) at 5000×, 10,000×, and 20,000× magnification, followed by energy-dispersive X-ray spectroscopy. Results: The surfaces of BioRoot and DiaRoot sealers revealed a relatively uniform distribution of irregular micro-sized particles aggregated in clusters, with the particle size ranging from 1 to 65 µm and 0.4 to 55 µm, respectively. OneFill, iRoot, and CeraSeal demonstrated irregularly shaped particles with particle sizes of 0.5 to 105 µm, 0.5 to 195 µm, and 0.3 to 68 µm, respectively. The EDX microanalysis revealed that oxygen, calcium, and carbon were found in all the tested sealer materials. Silicone and zirconium were absent in DiaRoot, but DiaRoot contained fluoride and ytterbium. Moreover, aluminum was noted in DiaRoot, One Fill, and CeraSeal, and chloride was only observed in BioRoot. FTIR analysis revealed strong absorption bands at 666 cm−1 and 709 cm−1 in BioRoot. Bands at 739 cm−1, 804 cm−1, 863 cm−1, 898 cm−1, and 1455 cm−1 were observed in DiaRoot. Bands at 736 cm−1 and 873 cm−1 in OneFill suggested the presence of C-H bending. Similarly, bands were observed at 937 cm−1, 885 cm−1, 743 cm−1, and 1455 cm−1 in iRoot, representing C-H stretching. Conclusions: All root canal sealers had diverse surface morphologies that contained irregular, micro-sized particles that were uniformly distributed, and they lacked heavy metals. All the experimental sealers comprised mainly calcium, oxygen, and carbon.

The Influence of Progressive Cladding Technologies on Layers Quality

Experimental work was focused on the restoration of functional surfaces of shaped parts of the molds for high-pressure casting of aluminum alloys. Paper presents results of the research aimed at determination of the quality of renovation layers applied by laser technology and TOP TIG technology. The TruDisk 4002 solid-state disk laser and the AirLiquide TOPTIG 220 welding power source were used to create the layers. Clad was applied to the base material of nickel-chromium-molybdenum vanadium steel 1.2714, DIN-56NiCrMoV7, with a hardness of 44 HRC. Uddeholm Deivar 1.2344, DIN-X40CrMoV51 wire with a 1.2 mm diameter was used as an additive material. The clad quality was evaluated using the light and electron microscopy and EDX microanalysis. The size of the heat affected zone (HAZ) and the presence of internal defects in the clads were determined. HAZ was set as max. a min. Value. Experimental work was supplemented by evaluation of tribological properties of clads by Pin-on-disc method.

Analysis of Defects Associated with Manufacturing Keys for Brass Musical Instruments

This article deals with the problematics of the production of small castings using gravitational investment casting. These are castings with a relatively complex shape, which are used as parts of trigger assembly for musical wind instruments. During their production, various defects occur which are connected with the casting process. The aim of this article is to describe the defects and suggest possible methods for removing them. The first step was to find and identify these defects using metallographic and EDX microanalysis. Furthermore, a simulation calculation of the casting process was used to determine the influence of the casting geometry on casting quality. Based on these analyses, the most suitable alloy and casting system geometry were proposed for the production of the casting.

Effect of phase and elemental composition, structure, and texture of multilayer coatings based on TiCN and TiNbCN on the electrochemical behavior of high-speed steel in 3% NaCl solution

Thin multilayer TiCN and TiNbCN coatings were obtained on a high-speed steel M2 by pulsed magnetron sputtering. The content of N2 and CH4 in the gas mixture was changed to obtain nanostructured layers with different phase and elemental compositions, structure, and texture. The microstructure, defects, and elemental composition of the coatings were investigated using an Ultra 55 field emission electron microscope with an EDX microanalysis system. The phase composition and texture of the coatings were determined using a Shimadzu XRD-6000 X-ray diffractometer with Cu-Kα radiation. Voltammetry and impedance spectroscopy on the coated samples were performed in a 3% NaCl solution. The corrosion behavior of the coatings was characterized by the corrosion current density and polarization resistance (at the corrosion potential). It is shown that the investigated coatings are electrochemically active, and corrosion processes occur not only on the substrate in the discontinuities of the coating but also on the surface of the coating. The TiN-TiCN-TiCN multilayer coating with a maximum content of the three-component phase TiC0.496N0.502, a minimum content of the carbide phase TiC, a maximum texture coefficient, a minimum crystallite size, lower internal stresses and deformations of the crystal lattice has the lowest corrosion current density 0.75 µA cm−2 among the investigated coatings. Niobium improves corrosion resistance, but the presence of a significant amount of the TiC carbide phase in the TiNbCN coating reduces this effect. The morphology of the coating surface after the electrochemical test was studied. The maximum damage of the surface layer is observed for the multilayer TiCN (1) coating.

Green synthesis and photoluminescence properties of gold nanoparticles with irregular shapes

Inspired by several conventional ideas, the green phytosynthesis of gold nanoparticles (AuNPs) has many advantages over known chemical and physical methods of preparing AuNPs. With no need for special conditions, one can use this approach for large-scale synthesis. Here, we report the green synthesis of AuNPs with irregular shapes by the bio-reduction of tetrachloroauric acid by the extract of Juniperus communis L. The resulting AuNPs were characterized by UV-Vis spectroscopy, TEM, AFM, SAED, and EDX microanalysis. In the background of the unique morphology of AuNPs, we registered the blue-to-green photoluminescence with a broad plasmon signal that indicates the contributions of AuNPs with different sizes and shapes. The phytosynthesized AuNPs are promising candidates for the application in biomedicine and morphology-dependent surface plasmon resonance sensors.

ESEM-EDX Microanalysis at Bone-Implant Region on Immediately Loaded Implants Retrieved Postmortem.

The aim of the study was to analyze the microchemistry of human bone in different regions of interest (ROIs) on histologic samples of implants retrieved postmortem by the innovative use of an environmental scanning electronic microscope (ESEM) connected to energy-dispersive x-ray spectroscopy (EDX). Maxillary and mandibular bone blocks with inserted implants (n = 12) were obtained postmortem from a patient. The histologic samples were observed uncoated using ESEM in quadrant backscattered condition. Two ROIs (approximately 750 × 500 μm) for each implant were analyzed corresponding to the cortical thread (cortical ROI) and the middle part of each implant (approximately 3.0 mm below; middle ROI). Different electron-dense bone tissue areas were detected through grayscale intensity quantification of ESEM images. Calcium (Ca), phosphorous (P), and titanium (Ti; atomic %) were evaluated by EDX, and Ca/P ratios were calculated and used as the index to identify areas with different mineralization. The presence of Ti contaminants was investigated by EDX microanalysis. Additional ROIs approximately 2.0 mm from the implant interface and not in connection with the implant surface were analyzed as the control. Four bone areas (BAs) with different degrees of mineralization (from 1 as the lowest mineralized to 4 as the highest mineralized) were identified by Ca and P content and by tissue electron density. BA1 (bone marrow areas) and BA2 (areas with active bone remodeling) proved to have low levels of Ca and P, while BA3 (mineralized new bone areas) and BA4 (control cortical bone) had higher content of Ca and P and higher electron density. Mandibular ROIs displayed higher percentages of BA3 and BA4, while maxillary ROIs revealed a greater presence of BA2 and moderate presence of BA1. Control bone showed a high percentage of BA4. Cortical and middle ROIs showed similar BA distribution within mandibular bone, whereas in maxillary bone, a slightly higher presence of BA1 was observed. Ti ions were detected in ROIs of all specimens; the atomic % significantly decreased in the most distant areas. Ti particles were observed close to the implant interface. Analyses 2.0 mm distant from the implant thread revealed low traces of Ti in healthy bone tissue. The high percentage of BA3 and BA4 in mandibular blocks associated with low presence of BA2 suggested the fast formation of compact bone tissue after 7 months from the implant placement. The presence of BA2 in maxilla blocks suggested active bone remodeling still present after 7 months. Ti particles were observed throughout the ROIs with and without bone remodeling activity. ESEMEDX resulted as a suitable technique to obtain more complete information on microchemistry composition and density/mineralization of bone around implants. For clinical significance, maxillary and mandibular peri-implant bone revealed different mineralization patterns, which means different healing times. The presence of Ti particles at the bone-implant interface and ion translocation, likely due to wear forces in the times following the implant insertion, do not affect the bone remodeling process.

The way to increase the monovalent ion selectivity of FujiFilm® anion-exchange membranes by cerium phosphate modification for electrodialysis desalination

Recently, the selectivity of ion-exchange membranes and its control have been the subject of numerous fundamental and applied studies. This paper reports an enhanced monovalent anion selectivity of hybrid membrane based on the FujiFilm® Type I anion-exchange membrane and in situ synthesized cerium phosphate (CeP) with a gradient distribution over the membrane thickness. The Cl/SO4-selectivity coefficient (P(Cl/SO4)) of hybrid membranes reached 6.2. The effect of modification on the Cl/SO4 selectivity passed through a minimum as the total concentration of the external solution increased from 0.04 M to 1 M. For low concentration electrolytes, Cl/SO4-selectivity improving was attributed to partial neutralization of positive fixed charges by negative fixed charges of cerium phosphate, which causes an effective decrease of ion-exchange capacity and reduction of electrostatic selectivity factor favouring sulfate transport; for high concentration electrolytes, to the formation of narrow transport channel between the surface of the inorganic nanoparticle and the pore wall, which causes a decrease of sulfate transport due to the size sieving effect. The hybrid membranes and cerium phosphate were characterized using ATR FTIR and 31P MAS NMR spectroscopy, XRD analysis and scanning electron microscopy with EDX microanalysis.

A Combined Non-Destructive and Micro-Destructive Approach to Solving the Forensic Problems in the Field of Cultural Heritage: Two Case Studies

The present paper discusses the importance of non-destructive and micro-destructive technology in forensic investigations in the field of cultural heritage. Recent technological developments and the wide availability of modern analytical instrumentation are creating new possibilities for performing scientific measurements and acquiring data directly on-site—thereby limiting, where possible, sampling activity—as well as learning about the technologies and materials that were employed in the past to create cultural assets. Information on periods, chemical composition, manufacturing techniques, etc., can be gathered more easily. Overall, the benefits of on-site forensic investigations are multiple, including the potential to increase substantially the speed and efficacy of the criminal justice system. However, such benefits are only realized when data quality is guaranteed and findings can be used as forensic evidence in court. The present paper shows data from the non-destructive and micro-destructive analysis of different artworks and objects provided by the Cosenza Carabinieri Unit for the Protection of Cultural Heritage and Anti-Counterfeiting (Calabria, Italy). In particular, two oil paintings on canvas depicting cherubs (Italian: putti), recovered as fragments of larger religious artworks, and two bronze belt and helmet fragments were investigated. In the first case, the research aimed to define the original pictorial layer, identify any reconstruction pictorial areas or pictorial retouching, assess the state of conservation, reconstruct the previous conservation treatments, and provide indications about the chronology of the artworks. In the second case, analysis was performed both to define the bronze chemical composition and the origin of the soil (earth) found within the objects during their recovery. For these purposes, the analytical approach involved the use of non-destructive and micro-destructive analysis as follows: infrared reflectography (IRR), ultraviolet-induced visible fluorescence (UV), X-ray fluorescence analysis (XRF), digital optical microscopy (DOM), scanning electron microscopy equipped with EDX microanalysis (SEM-EDX), and Fourier transform infrared spectroscopy (FT-IR). The results made it possible to collect valuable diagnostic information and answer questions posed by the institutions for the resolution of various doubts about forensic science and cases concerning the seizure, recovery, or return of archaeological or historical-artistic objects of cultural interest.

Trichome Biomineralization and Soil Chemistry in Brassicaceae from Mediterranean Ultramafic and Calcareous Soils.

Trichome biomineralization is widespread in plants but detailed chemical patterns and a possible influence of soil chemistry are poorly known. We explored this issue by investigating trichome biomineralization in 36 species of Mediterranean Brassicaceae from ultramafic and calcareous soils. Our aims were to chemically characterize biomineralization of different taxa, including metallophytes, under natural conditions and to investigate whether divergent Ca, Mg, Si and P-levels in the soil are reflected in trichome biomineralization and whether the elevated heavy metal concentrations lead to their integration into the mineralized cell walls. Forty-two samples were collected in the wild while a total of 6 taxa were brought into cultivation and grown in ultramafic, calcareous and standard potting soils in order to investigate an effect of soil composition on biomineralization. The sampling included numerous known hyperaccumulators of Ni. EDX microanalysis showed CaCO3 to be the dominant biomineral, often associated with considerable proportions of Mg—independent of soil type and wild versus cultivated samples. Across 6 of the 9 genera studied, trichome tips were mineralized with calcium phosphate, in Bornmuellera emarginata the P to Ca-ratio was close to that of pure apatite-calcium phosphate (Ca5(PO4)3OH). A few samples also showed biomineralization with Si, either only at the trichome tips or all over the trichome. Additionally, we found traces of Mn co-localized with calcium phosphate in Bornmuellera emarginata and traces of Ni were detected in trichomes of the Ni-hyperaccumulator Odontarrhena chalcidica. Our data from wild and cultivated plants could not confirm any major effect of soil chemistry on the chemistry of trichome biominerals. Hyperaccumulation of Ni in the plants is not mirrored in high levels of Ni in the trichomes, nor do we find large amounts of Mn. A comparison based on plants from cultivation (normal, calcareous and serpentine soils, Mg:Ca-ratios ca 1:2 to 1:20) shows at best a very weak reflection of different Mg:Ca-ratios in the mineralized trichomes. The plants studied seem to be able to maintain highly conserved biomineralization patterns across a wide range of soil chemistries.

Micro-Nano Surface Characterization and Bioactivity of a Calcium Phosphate-Incorporated Titanium Implant Surface.

The surface topography of dental implants and micro-nano surface characterization have gained particular interest for the improvement of the osseointegration phases. The aim of this study was to evaluate the surface micro-nanomorphology and bioactivity (apatite forming ability) of Ossean® surface, a resorbable blast medium (RBM) blasted surface further processed through the incorporation of a low amount of calcium phosphate. The implants were analyzed using environmental scanning electronic microscopy (ESEM), connected to Energy dispersive X-ray spectroscopy (EDX), field emission gun SEM-EDX (SEM-FEG) micro-Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) before and after immersion in weekly refreshed Hank’s balanced salt solution (HBSS) for 28 days. The analysis of the samples before immersion showed a moderately rough surface, with micropits and microgrooves distributed on all of the surface; EDX microanalysis revealed the constitutional elements of the implant surface, namely titanium (Ti), aluminum (Al) and vanadium (V). Limited traces of calcium (Ca) and phosphorous (P) were detected, attributable to the incorporated calcium phosphate. No traces of calcium phosphate phases were detected by micro-Raman spectroscopy. ESEM analysis of the implant aged in HBSS for 28 days revealed a significantly different surface, compared to the implant before immersion. At original magnifications <2000×, a homogeneous mineral layer was present on all the surface, covering all the pits and microgrooves. At original magnifications ≥10,000×, the mineral layer revealed the presence of small microspherulites. The structure of these spherulites (approx. 2 µm diameter) was observed in nanoimmersion mode revealing a regular shape with a hairy-like contour. Micro-Raman analysis showed the presence of B-type carbonated apatite on the implant surface, which was further confirmed by XPS analysis. This implant showed a micro-nano-textured surface supporting the formation of a biocompatible apatite when immersed in HBSS. These properties may likely favor bone anchorage and healing by stimulation of mineralizing cells.

Corrosion Behavior of Electrodeposited Nickel Coating Reinforced by Cr&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Particles

The objective of this work is the characterisation of the composite deposits Ni-Cr2O3 on copper substrate; these deposits are obtained from bath of electro-deposition of Nickel watts. The different electrodeposited layers are characterized by various analytical techniques such as adhesion quality, corrosion tests, Vickers microhardness, morphology by scanning electron microscopy Followed by EDX microanalysis and X-ray diffraction. The corrosion tests are realized in a solution of 3.5 % NaCl using lost mass method, polarization and impedance spectroscopy techniques. It was found that the composite coatings Ni-Cr2O3 have an homogeneous and compact morphology, well crystallized and exhibit a high degree of codeposition of Cr2O3 particles incorporated in the nickel matrix. The co-deposited films have very good hardness, adhere perfectly to the substrate and are more resistant to corrosion.

Biogenic Contamination and Mineral Pseudo-Biogenic Structures in Earth Rocks and Astromaterials

Bacterial paleontology studies the roles played by organisms in the genesis of sediments and ores. It is, therefore, important to clearly distinguish in-situ biological objects present in the rock material from various contaminants of later origin and from mineral structures that merely resemble organisms. The same is crucial for correct interpretation of alleged biogenic structures found in meteorites. The use of a scanning electron microscope equipped with an EDX microanalysis system and designation of model objects from previously studied rock samples allows us to address this problem. This approach also needs to be applied to previously discovered structures.

Photocatalytic Generation of Hydrogen from Organic Substances Using Iron-Containing Composites under the Conditions of UV and Visible Irradiation

Morphological features of iron-containing composites based on silicon, titanium, vanadium, and boron nitrides and prepared by self-propagating synthesis were examined by scanning electron microscopy, and the content of elements (B, Si, N, Ti, V, O, Fe, C, Al, Mg, Ca) on their surface was quantitatively estimated using an attachment for EDX microanalysis. The optical properties of the composites were studied, and the band gap values for the semiconductors incorporated in the ceramic matrix were determined. A comparative evaluation of the performance of the composites in hydrogen generation from solutions of organic substances (НСООН, Н2С2О4, malic acid, sucrose) under UV and visible irradiation was made. The efficiency of the photocatalytic generation of hydrogen under the action of visible light is shown to be associated both with the composition of the ceramic matrix containing semiconductor compounds and with the occurrence of the photo-Fenton process in the solution in the presence of hydrogen peroxide.

New results in ancient Maya rituals researches: The study of human painted bones fragments from Calakmul archaeological site (Mexico)

The funeral chambers of the ancient city of Calakmul (Mexico) and the individuals who were buried in them have brought in recent decades new knowledge about the beliefs and funeral customs of the pre-Hispanic Maya. Tombs and bodies were prepared as part of the rituals that should favor the return of ch'ulel to the Underworld, known as Xibalbá by the ancient Maya. The ch'ulel is one of the two anemic entities that inhabit the individual, equivalent to our concept of the soul. Bodies preparation included coloured scented body ointments application, with a deep symbolic connotation and probably also a conservative purpose. The aim of this research was to characterize pigments and binders used by ancient Maya in body ointments remains in human bones samples from Calakmul Maya archaeological site, and the latter, the physical–chemical identification of organic components mixed with these colours for funeral use, can be considered the great challenge of this research due to the limited results that have been gathered on the subject to date. For this purpose, a multi-analytical approach based on the combination of several non-destructive and micro-destructive analytical techniques has been selected. Pigments were studied by transmitted light optical microscopy, FT-IR spectroscopy in ATR mode, diffuse reflectance UV–VIS spectrometry, and EDX microanalysis provided elemental information in order to find characteristic elements useful to identify the unknown pigments. Surface of the samples was observed with Scanning Electron Microscopy (SEM). Gas-Chromatography coupled with Mass Spectrometry (GC–MS) and Pyrolysis-Gas-Chromatography-Mass Spectrometry (Py-GC-MS) were performed in order to collect information about organic fraction used as binding media. The multi analytical approach identified red pigments as Red Earth (or ochre) and Cinnabar, while the results obtained on organic fractions lead us to suggest the presence of lipidic and gum- based compounds.

The Use of ESEM-EDX as an Innovative Tool to Analyze the Mineral Structure of Peri-Implant Human Bone.

This study aimed to investigate the mineralization and chemical composition of the bone–implant interface and peri-implant tissues on human histological samples using an environmental scanning electron microscope as well as energy-dispersive x-ray spectroscopy (ESEM-EDX) as an innovative method. Eight unloaded implants with marginal bone tissue were retrieved after four months from eight patients and were histologically processed and analyzed. Histological samples were observed under optical microscopy (OM) to identify the microarchitecture of the sample and bone morphology. Then, all samples were observed under ESEM-EDX from the coronal to the most apical portion of the implant at 500x magnification. A region of interest with bone tissue of size 750 × 500 microns was selected to correspond to the first coronal and the last apical thread (ROI). EDX microanalysis was used to assess the elemental composition of the bone tissue along the thread interface and the ROI. Atomic percentages of Ca, P, N, and Ti, and the Ca/N, P/N and Ca/P ratios were measured in the ROI. Four major bone mineralization areas were identified based on the different chemical composition and ratios of the ROI. Area 1: A well-defined area with low Ca/N, P/N, and Ca/P was identified as low-density bone. Area 2: A defined area with higher Ca/N, P/N, and Ca/P, identified as new bone tissue, or bone remodeling areas. Area 3: A well-defined area with high Ca/N, /P/N, and Ca/P ratios, identified as bone tissue or bone chips. Area 4: An area with high Ca/N, P/N, and Ca/P ratios, which was identified as mature old cortical bone. Bone Area 2 was the most represented area along the bone–implant interface, while Bone Area 4 was identified only at sites approximately 1.5 mm from the interface. All areas were identified around implant biopsies, creating a mosaic-shaped distribution with well-defined borders. ESEM-EDX in combination with OM allowed to perform a microchemical analysis and offered new important information on the organic and inorganic content of the bone tissue around implants.

Improving coated carbide tool life through wide peening cleaning (WPC) during the wet milling of H13 tool steel

The (AlCrN–TiAlN) bi-layer PVD (physical vapor deposition) coating was post-treated by a wide peening cleaning (WPC) process at various pressures and times. The micro-mechanical and adhesion properties of the studied coatings were evaluated in terms of their effects on machining performance during the wet milling of H13 tool steel. A comprehensive characterization of the cutting-edge geometry was performed by infinite focus microscope and EDX micro-analyses. Micro-mechanical and adhesion properties of the studied coatings were analyzed by nanoindentation, a nano impact test, ramped load scratch test, a repetitive load wear test and SEM. The wear performance was found to be associated with the fatigue resistance, which was improved by micro-mechanical characteristics, such as, H3/E2 ratio and yield stress. Coating adhesion deteriorated as WPC pressure increased. The data of critical load for crack initiation (Lc1) and the wear evolution at a subcritical load of 1 N demonstrated this gradual deterioration in coating adhesion. However, the tool life was improved by 35% at a pressure of 0.2 MPa due to the superior balance found between fatigue resistance and coating adhesion.

ПОТЕНЦІОДИНАМІЧНЕ ОСАДЖЕННЯ ПОЛІПІРОЛУ НА ПОВЕРХНІ АМОРФНОГО СПЛАВУ СКЛАДУ Al87Ni8Y5

Polypyrrole films were deposited on the surface both of the outer and contact sides of the Al87Ni8Y5 amorphous alloy electrodes by potentiodynamic oxidation of 0.1 M pyrrole in 0.5 M H2SO4 aqueous solution. It was found that the oxidation of pyrrole on Al87Ni8Y5 amorphous alloy electrodes occurs comparatively easy and already during the first cycle of potential scanning a nanofilm of polypyrrole is formed. The formation of polypyrrole film essentially accelerates during following cycles of potential scanning. Cyclic voltammogramms has been analyzed and the process of electrochemical oxidation of pyrrole and redox transformations of polypyrrole at these electrodes is described. It is shown that the difference in film topology is due to the surface topology of electrodes, which determines stability of surface oxide films on these surfaces. Studies of the electrode surface topology and also morphology, structure and composition of polypyrrole films produced on an amorphous alloy electrode were carried out using Fourier-transform infrared spectro¬sco¬py with attenuated total reflection (FTIR-ATR), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). It has been confirmed using FTIR analysis that the films deposited on the surface of the Al87Ni8Y5 electrodes corespond to polypyrrole which are in the form of hydrosulfate salt. The analysis of the received electron microscopy images shown that polypyrrole films produced both on the contact and outer sides of the working electrodes has developed surface topology, which depends on surface quality and nature of amorphizing additive in electrode alloy. In addition, it is likely that a significant number of aggregates of polypyrrole macromolecules are formed in the solution, which further play the role of electrodes, where the oxidation of the corresponding monomer from its aqueous solution takes place. The results of EDX microanalysis shown presence in the polymeric films of small amount of metal impurities (in the form of sulfates mainly), which formed in the result of the corrosion of working electrode.

Effect of Cr content on microstructure and oxidation resistance of laser-clad Cu-Ni-Fe-Mo-xCr alloy coating

Cu-Ni-Fe-Mo-xCr type alloy coatings with different Cr content were produced on a medium carbon steel substrate by laser cladding in this investigation. The effect of Cr content on macro-quality, microstructure, phase structure and high temperature oxidation resistance of the coatings was revealed by macro photography, optical microscopy (OM), environmental scanning electron microscopy (ESEM) incorporating with EDX microanalysis, X-ray diffraction (XRD) analysis, respectively. Results showed that, the coatings with Cr content ranging from 0 to and 5 wt% are smooth and crack free while the coatings with Cr content ranging from 7.5 to and 10 wt% are smooth but cracked. The volume content of second phase (Fe,Ni,Si,Cr)2Mo and the high temperature oxidation resistance of the coatings are both increased with an increase in Cr content.