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... Jaszowiec (Poland). 17-23 Sep 1995. Institute of Atomic Energy, Swierk (Poland).

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Hard surface finishing represents the final manufacturing step for functional areas of machine elements in state-of-the-art production. Raceways of rolling bearing rings are ground and honed to the required low roughness. Plastic deformation is restricted to a narrow edge zone of the hardened steel. Reheating of the machined components below the martensite tempering or bainite transformation temperature results in a marked decrease of the XRD line width on the surface. The investigated samples are made of through-hardened standard bearing steel 100Cr6 (international denotation: SAE 52100). On the basis of a material model that explains the effect as a complex diffusion process of dislocational carbon segregation, i.e. static strain aging, the measured kinetics of the XRD line width reduction is simulated by an Arrhenius-type equation, which describes the rate-controlling reaction step of temper carbide dissolution. The formation of a small ...

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The influence of selenium dioxide (SeO2) on the microstructure and electrodeposition of manganese coatings obtained from a sulfate based neutral solution was investigated by material characterization methods and electrochemical techniques. The crystal structure and surface morphology of these coatings were studied by scanning electron microscopy (SEM) and powder X-ray diffraction spectroscopy (XRD), respectively. The SEM and XRD data showed that SeO2 could effectively accelerate phase transformation, and facilitate leveled and fine grain growth. The electrochemical results indicated that SeO2 could inhibit hydrogen evolution reaction and promote manganese deposition. The action of selenium dioxide in manganese deposition was found to be a reduction and adsorption mechanism. The process cou...

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Several compatibilising systems were added to high-density polyethylene (HDPE) and polyamide 6 (PA6) blends in the presence of an organically modified montmorillonite (OMM). All the blends were prepared by using a co-rotating twin-screw extruder and characterized by SEM, TEM and XRD analyses. In addition, the rheological behaviour and the mechanical properties - tensile and impact - were evaluated. The presence of OMM affects the dimensions of the polymeric phases in the blend but not their mutual adhesion, granted only by the compatibilisers. TEM, SEM and XRD analyses indicated that there is a strict correlation between the compatibilisation level and the final interlayer distance achieved by OMM. Even if some filled compatibilised blends showed a fairly good morphology - in terms of phas...

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High-energy synchrotron x-ray diffraction (XRD) has been used to quantify load transfer in bovine plexiform bone. By using both wide-angle and small-angle XRD, strains in the mineral as well as the collagen phase of bone were measured as a function of applied compressive stress. We suggest that a greater proportion of the load is borne by the more mineralized woven bone than the lamellar bone as the applied stress increases. With a further increase in stress, load is shed back to the lamellar regions until macroscopic failure occurs. The reported data fit well with reported mechanisms of microdamage accumulation in bovine plexiform bone.

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In this work AISI 1045 steel were duplex treated via plasma nitriding of chromized layer. Samples were pack chromized by using a powder mixture consisting of ferrochromium, ammonium chloride and alumina at 1273K for 5h. The samples were then plasma-nitrided for 5h at 803K and 823K, in a gas mixture of 75%N2+25%H2. The treated specimens were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and Vickers micro-hardness test. The thickness of chromized layer before nitriding was about 8mm and it was increased after plasma nitriding. According to XRD analysis, the chromized layer was composed of chromium and iron carbides. Plasma nitriding of chromized layer resulted in the formation of chromium and iron nitrides and carbides. The hardness of the duplex layer...

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This work was initiated to examine the effect of frequency and treatment temperature on the formation of nitrided layers and surface characteristics during plasma nitriding. Plasma nitriding experiments were performed with 316L austenitic stainless steel at the temperatures 400 .deg. C and 500 deg. C using a pulsed d.c. plasma with various frequencies in an atmosphere of N{sub 2}-H{sub 2} gas mixture. The microstructure and thickness of the nitrided layer and morphology of the nitrided surface were investigated using OM, SEM, XRD, EDS and AFM. XRD patterns revealed that the surface layer formed at 400 deg. C consisted of S phase only and CrN+Fe{sub 4}N nitrides at 500 .deg. C and no change of phase composition with frequency was observed. The compound layer thickened slightly with increased frequency. Also, the surface roughness increased as the frequency of the pulsed plasma increased from 50 to 5,000Hz.

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For the first time, rheological phase method, a simple and effective route, is applied to synthesize novel cathode material LiCoPO4. X-ray diffraction spectrometer (XRD), X-ray photoelectron spectrometer (XPS), transmission electron microscope (TEM) and electrochemical impedance spectroscopy (EIS) are taken to investigate this material, respectively. XRD figure shows that the rheological sample is better crystallized than the solid-state one. XPS result of the rheological sample exhibits that the valence of Co is 2+. TEM images show that better dispersed particles with smaller size can be formed by rheological method comparing to the solid-state route. Charge-discharge test is carried out in the range of 3.0-5.0 V at 0.2 mA cm-2. The initial discharge capacity for rheological phase and solid-state powder is 71.5 and 30.9 mAh g-1, respectively. The better electrochemical property should be ascribed to the better crystallized rheological phase ...

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Microhardness decarburization profiles are often used in the industry to estimate the carbon distribution in steels. For quantitative evaluation, an analysis based on diffusion theory must be performed, the fundamentals and mathematical basics of which are presented. If the relationship between hardness and carbon content is known, microhardness-distance curves of steels can be analyzed in this way. For martensitic grades, for instance, a linearized expression holds in the concentration range from 0.15 to 0.6 m.% C. Microhardness depth profiles of higher carbon steels and other microstructures, however, are also evaluated in the literature. The applicability of quantitative diffusion modeling is discussed in detail. Through hardenable rolling bearing steel 100Cr6 (1.3505, SAE 52100) serves as model material: carbon concentration-distance curves are measured with high accuracy by secondary ion mass spectrometry (SIMS) and compared with microhardness decarburization profiles for tempered ...

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The CaWO_4:Ln"3"+ SiO_2 (Ln=Tb, Dy and Ho) nanoparticles were synthesized via a combustion process at 800 "oC, using citric acid as chelating agent and fuel, ammonium nitrate as fuel, boric acid as flux material and silica as supports. The persistent phosphor nanoparticles were characterized by X-ray diffraction (XRD), reflectance UV-vis and fluorescence spectroscopy (PL) and transmission electron microscopy (TEM) techniques. XRD patterns indicated that crystalline calcium tungstate with scheelite structure was produced. The reflectance UV-vis spectra showed the broad absorption band of WO_4"2"- groups and the PL spectra showed the WO_4"2"- wide excitation band, broad emission band of WO_4"2"- and characteristic emissions of Ln"3"+ ions. The average particle sizes were determined by TEM, which are about 50 nm.

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A technique for following sialon formation in situ by high temperature X-ray diffraction (HT-XRD) was developed. The composition chosen for study was an yttrium #alpha#-sialon with x=0.4. Powder compacts containing silicon nitride, aluminum nitride and yttria powders were pre-sintered at 1350 C and then studied by HT-XRD at temperatures between 1450 and 1580 C and nitrogen pressures of 0.11 MPa. The furnace was made from graphite coated with porous silicon nitride/silicon carbide. The coating prevented silicon carbide formation in the sample up to 1600 C. X-ray diffraction results show the formation of a Y_1_0Al_2Si_3O_1_8N_4 phase at 1350 C, which dissolved to form #alpha#-sialon and other phases at higher temperatures. The amounts of #alpha#-sialon formed are similar to the amounts reported by other authors. An empirical method was used for the calculation of activation energy for the silicon nitride to #alpha#-sialon transformation and ...

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Molecular recognition by calix[6]arene-based receptors bearing three primary alkylamino side chain arms (1) is described. Complexation of ZnII ion provides the dinuclear m-hydroxo complex ${{\\bf 2}{{{\\rm OH}\\hfill \\atop {\\rm G}\\hfill}}}$, XRD characterization of which, together with solution studies, provided evidence of its hosting of neutral polar organic guests G. Treatment of this complex with a carboxylic acid or a sulfonamide (XH) results in the formation of mononuclear species ${{\\bf 3}{{{\\rm X}\\hfill \\atop {\\rm G}\\hfill}}}$, one of which (X = Cl) has been characterized by XRD. A dicationic complex ${{\\bf 3}{{{\\rm RNH}{_{2}}\\hfill \\atop {\\rm G}\\hfill}}}$ is obtained upon treatment of ${{\\bf 2}{{{\\rm OH}\\hfill \\atop {\\rm G}\\hfill}}}$ with a mixture of an alkylamine and a strong acid....

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17-4PH stainless steel was modified by direct current (DC) plasma nitriding and titanium nitride film duplex treatment in this study. The microstructure, wear resistance and corrosion resistance were characterized by X-ray diffraction (XRD), pin-on-disk tribological test and polarization experiment. The results revealed that the DC plasma nitriding pretreatment was in favor of improving properties of titanium nitride film. The corrosion resistance and wear resistance of duplex treatment specimen was more superior to that of only coated titanium nitride film.

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HgTe rod-shape composed of crystalline particles has been prepared by a hydrothermal method, and characterized by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transition electron microscopy (TEM). The effects of capping agents, reductants, reaction temperatures, and reaction times on crystal structures and shapes of HgTe have been investigated. The results showed that the CTAB as capping agent plays a crucial role in the hydrothermal process. The synthesis procedure is simple and uses less toxic reagents than the previously reported methods.

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A chromium-free conversion coating for magnesium alloys were described. The conversion coating could be obtained when AZ31D magnesium alloy was immersed in a solution containing a manganese salt, phosphate and an inhibitor. Corrosion resistance of the chemical conversion coating was evaluated by anodizing polarization curve and salt immersion. XRD analysis showed that the conversion coating was mainly composed of Mn{sub 3}(PO{sub 4}){sub 2}. The morphology of the coating is observed by using SEM. The effect of electrolyte pH and concentration of inhibitor on coating growth are investigated. (orig.)

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In this paper, we report the electrochemical characteristics of a novel cathode material, Li{sub 2}CoPO{sub 4}F, prepared by solid-state reactions. The solid-state reaction mechanism involved in synthesizing the Li{sub 2}CoPO{sub 4}F also is analyzed in this paper. When cycled between 2.0 V and 5.0 V during cyclic voltammetry measurements, the Li{sub 2}CoPO{sub 4}F samples present one, fully reversible anodic reaction at 4.81 V. When cycled between 2.0 V and 5.5 V, peaks occurring at 4.81 V and 5.12 V in the first anodic scan evolved to one broad oxidative, mound-like pattern in subsequent cycles. Correspondingly, the X-ray diffraction (XRD) pattern of the Li{sub 2}CoPO{sub 4}F electrode discharged from 5.5 V to 2.0 V is slightly different from the patterns exhibited by a fresh sample and the sample discharged from 5.0 V to 2.0 V. This difference may correspond to a structural relaxation that appears above 5 V. In the constant current cycling measurements, the ...

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The effect of thermal pretreatment in N[sub 2] up to 723 K and the activation treatments in H[sub 2] and an inert atmosphere on the properties of Ni and Co activated-charcoal-supported catalysts were studied. Catalysts were characterized by means of N[sub 2] adsorption at 77 K, H[sub 2] chemisorption at room temperature, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The catalysts' activity and selectivity for acetone hydrogenation to 2-propanol under unusual and severe conditions (473 K and high overall acetone conversion) were also measured. TGA and XRD evidence was found for the charcoal-support-promoted NiO and CoO reduction to the metallic states when the catalysts were subjected to an inert atmosphere above 723 K caused a loss of acetone hydrogenation activity (calculated on a metal load basis) for both the Ni and Co activated-charcoal-supported catalysts, with respect to ...

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The Co-Si composites with a molar ratio of 2:1 are synthesized by ball-milling method and their potential as negative electrode materials of Ni-MH batteries is investigated. The microstructure, morphology and chemical state of the ball-milled Co-Si composites are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD patterns show that the ball-milled samples for 10 and 20 h contain Co, Si and Co{sub 2}Si phases, and the ball-milled samples for 40 and 60 h are mainly amorphous Co{sub 2}Si alloys. In contrast to the high initial discharge capacity (1012 mAh/g) obtained for the sample ball-milled for 10 h, the discharge capacities of the samples ball-milled for 40 and 60 h are very low. It indicates that the hydrogen storage capacity of pure Co{sub 2}Si alloy is very low. It is found that the formation of active Co nanoparticles and Si oxidation are responsible for the high ...

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Fe-doped TiO2 hollow spheres (Fe-THs) were synthesized by sol?gel process using carbon spheres as templates. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV?vis diffuse reflectance spectrum (DRS), N2 adsorption?desorption isotherms, Electron paramagnetic resonance (EPR) spectroscopy and Photoluminescence emission spectroscopy (PL). UV?vis spectra showed that Fe3+ doping could extend the absorption edge to the visible region. EPR spectra showed that Fe3+ was incorporated into the crystal lattice of TiO2, which could inhibit the recombination of photo-induced electron?hole pairs and improve the photocatalytic activity. The photocatalytic activities of the prepared samples were evaluated for the degradation of dye Reactive Brillia...

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An attempt has been made to grow L-tartaric acid nicotinamide (LTN); a complex of tartaric acid, by employing a modified unidirectional method. The crystalline structure and quality are investigated by single crystal XRD and rocking curve studies. The linear and nonlinear optical properties are studied by UV-vis-NIR spectral analysis, SHG test, phase matching and laser induced damage threshold measurement. For comparison, parallel growth of the crystal was carried out by conventional method and the properties of the LTN samples grown by the conventional and unidirectional methods are investigated. The mechanical, photoconductivity and dielectric behavior of LTN crystals are also investigated.

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In this paper, the influence of plasma nitriding at temperature 720 deg. C for 20 h on the surface microstructure and interface microstructure of electroplated chromium coating was investigated. In these conditions, interdiffusion, mixing and reaction phenomena of elements originating from the substrate and coating material are more likely to occur, thus increasing the bonding strength between the coating and carbon steel substrate. The change of the structures from the substrate side to the coating surface, and the effect of the substrate steel on the interface structure were studied by cross-sectional transmission electron microscope observation (XTEM). The nitride layer formed on the surface was analyzed by X-ray diffraction method (XRD). After treatment at above conditions a 6-7 {mu}m thick nitride compound layer was formed in surface region and the same thick carbide compound layer was also formed in the interface region between electroplated chromium coating ...

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A series of #alpha#-sialon (#alpha#') compositions containing mixed stabilising cations were prepared, by introducing additional CaO to a basic Sm #alpha#-sialon compositions. The thermal stability of these Sm-Ca-containing #alpha#-sialon phases was investigated using XRD, SEM and EDXS techniques. It was found that the addition of calcium into the Sm #alpha#-sialon systems greatly improved the stability of the #alpha#-sialon phases. Calcium was found to be incorporated into the #alpha#-sialon structure, coexistent with the samarium, and partitioning of the calcium and samarium was observed between the #alpha#' phase and grain boundary phases. This indicates a technique which may be used to improve the thermal stability of the #alpha#' phase while maintaining good refractory phases at the sialon grain boundaries.

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In this work, a new sol-gel auto-combustion method has been performed to synthesize single phase nickel ferrite nanocrystalline powders by using n-cetyltrimethylammonium bromide, as a cationic surfactant. The gels were prepared from ferric and nickel nitrates and citric acid. Ammonia was used as pH adjusting agent as well. The effects of the surfactant on the after combustion calcination process and the reduction of the resulting powder crystallite size which affects the magnetic properties of the material were investigated by XRD and DTA/TGA techniques. The results showed that the ignition of the gels in air have a self-propagating behavior. Addition of surfactant to the starting solution affected the crystallite size of the synthesized powders and their phase constitution. The crystallit...

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Reduction of silver myristate (AgMy) under mild thermal reaction conditions in a dipolar aprotic solvent i.e. N, N-dimethylformamide (DMF) has been carried out. UV-visible absorption measurements of dried and re-dispersible brown flocculants showed broad features of surface plasmon resonance (SPR) due to silver nanoparticles. The freshly isolated particles showed absorption bands at 414 and 485 nm, respectively, due to inter-particle coupling or clustering of silver ions and silver atoms. X-ray diffraction (XRD) pattern of fcc zero-valent silver resulted in crystallite size of about 10 nm. Scanning electron microscopy (SEM) revealed formation of rod shaped silver with increasing reaction temperature. Thermal analysis (TGA) showed about 10% weight loss due to organic capping.

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A micellar method has been used to prepare silver-coated cobalt (Co-Ag) nanoparticles. The synthesized particles have been deeply characterized by several methods, i.e., XRD, UV-Vis, TEM, XPS, and electrochemical techniques. There is every indication that the obtained particles show a truly core-shell structure. All the nanoparticles obtained under different conditions are in the size range 3-5 nm. High-resolution TEM (HRTEM), Fast Fourier Transformation (FFT), and Selected Area Electron Diffraction (SAED) indicated that the presence of hcp-Co and fcc-Ag, in which cobalt is located in the central area; meanwhile silver is at the edges of the nanoparticle. The absorption band of the Co-Ag colloid shifts to a longer wavelength and broadens relative to that of pure silver colloid. Voltammetric characterization allowed to determine the coverage of the cobalt core.

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To study the effect of CuO on the electrochemical properties of MgNi alloy, the MgNi-xCuO (x = 3, 5 and 10 wt%) composites were prepared by ball-milling method. The X-ray diffraction (XRD) analysis showed that the structures of the composites were amorphous. The cycle stability of the composites was improved compared to pure MgNi alloy due to the enhancement of the anti-corrosion property in the alkaline electrolyte, and the composite with 5 wt% CuO ball-milled for 15 h exhibited the best performance. Electrochemical impedance spectroscopy (EIS) and potential-step measurements indicated that the electrochemical kinetics of the composites was improved.

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Nuclear forensic activities, such as in illicit trafficking, can solve a problem who did it and can gain the basis for a response. Other than that, the forensics can be also applied to solve on what are materials, who is responsible, is there more, where was material diverted and what route did the material taken. BATAN, in fact , owns a lot of equipment which can be supported for nuclear forensics activities, such as, Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM) as well as X-Ray Diffraction (XRD). For the first step, BATAN has to be an active, participate member of The International Technical Working Group on Nuclear Smuggling (ITWG). BATAN can then collaborate not only with Indonesia Arm Forces and Police, but also with other foreign institutions to develop this activity with mutual advantages agreement.

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Soluble starch?based biodegradable and microporous microspheres (SDM-Ms) were prepared by emulsion chemical cross-linking technique using trisodium trimetaphosphate (TSTP) as the cross-linker. The resultant amorphous SDM-Ms were excellently identified by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The internal rupture and surface-controlled erosion were the predominant degradation mechanisms for SDM-Ms. The obtained SDM-Ms were applied to adsorb coix seed oil (CSO) by immersing method. The adsorption capacity of CSO within SDM-Ms was determined, namely 0.5238?g/g, and the thermal stability was shown higher than that of the free CSO. A burst release appeared in the second hour, followed by controlled release. Diffusion, d...

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Ag nanoparticles were prepared in a water-phase system with a mixture of silver-ammonia complex, sodium borohydride, and lauric acid according to molar feed ratio of approximately 6:3:1. The mechanism of preparation and separation by chemical reduction-protection method was explored. The as-synthesized Ag nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis spectroscopy, respectively. It was found that the size of high purity Ag particles was ranging from 30 to 50 nm with slight agglomeration. In addition, the as-synthesized wet Ag nanoparticles were dispersed stably in organic vehicle to formulate electrically conductive nanopaste. Upon direct-written and sintered, the array pattern of the nanopaste with the resolution of about 30 {mu}m was achieved with the electrical resistivity in the order of magnitude of 10{sup -5} {Omega} cm.

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The phase composition and microstructure of O'-sialon prepared from Chinese coal gangue have been studied. The use of Si powder is more effective than that of activated carbon or mainly carbon with a little silicon for reduction-nitridation. For specimens with 40% Si addition, more than 80% of O'-sialon may be obtained when nitrided at 1500 degree sign C. The formed O'-sialon was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The parameters for O'-Sialon preparation are optimized by computer pattern recognition program based on principal component analysis, the target parameter optimum regions with higher relative content of O'-Sialon was indicated by this way.

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Plasma nitriding was applied to improve the surface performance of titanium bipolar plate. XRD and SEM results showed a titanium nitride layer was formed after nitridation. In comparison with pure titanium, the interfacial contact resistance of plasma nitrided titanium was reduced to some extent by the nitridation treatment. However, high corrosion current was observed under electrochemical tests in 0.5 M H{sub 2}SO{sub 4} + 5 ppm HF. Both the electrical conductivity and corrosion resistance of the surface of plasma nitriding titanium did not reach the level of graphite. Some more improvements are expected in the plasma nitriding process or another surface modification on pure titanium. (author)

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The present investigation deals with the synthesis of nanostructured nickel ferrite (NiFe2O4) and their liquid petroleum gas-sensing characteristics. The 15-20nm size nickel ferrite has been synthesized at 700degreeC by a simple molten-salt route using sodium chloride as grain growth inhibitor. These nanoparticles exhibit significantly high response towards liquid petroleum gas (LPG) in comparison with ethanol vapor, hydrogen sulfide, ammonia and hydrogen. The gas response towards various gases at their 200ppm concentrations is investigated at 200-450degreeC. Different characterization techniques have been employed, such as differential thermal analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission elec...

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Commercially available organoclay (Closite 30B) was modified by using 3-aminopropyltriethoxysilane (APS) via a silylation reaction. Sodium clay (Closite Na) was treated by APS directly as a control. Such modified clays were further melt-compounded with polybutylene terephthalate (PBT). The morphology and properties of the modified organoclays were characterized with X-ray diffraction (XRD), transmission electrical microscopy (TEM), Infra-red spectroscopy, contact angle measurement, and thermogravimetric analysis (TGA). The effects of modified clays on the crystallization behavior of PBT were characterized by differential scanning calorimetry. The basal spacing of Closite Na was enlarged from 1.01 to 1.41 nm after APS treatment, indicating that the APS was intercalated into the clay interga...

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Natural rubber (NR) and its derivatives as renewable and biodegradable materials have attracted considerable attention because of the serious pollution problems caused by synthetic materials and a shortage of resources. A new semi-interpenetrating polymer network (semi-IPN) based on epoxidised natural rubber and polyvinyl alcohol containing maleic acid as a crosslinking reagent was synthesized and characterized by FTIR, XRD, SEM, swelling ratio in both distilled water and toluene, and mechanical properties. The curing time and dose of maleic acid were varied from 10 to 60min, and from 10 to 60% (w/w), respectively. An IR spectroscopic study indicated the presence of an ester linkage at 1730cm-1 in maleic acid crosslinked with PVA in semi-IPN films. In addition, the crystalline content of P...

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A poly(ether urethane) (PEUR)/poly(ethylene oxide) (PEO)/SiO2 based nanocomposite polymer is prepared and employed in the construction of high efficiency all-solid-state dye-sensitized nanocrystalline solar cells. The introduction of low-molecular weight PEUR prepolymer into PEO electrolyte has greatly enhance the electrolyte performance by both improving the interfacial contact properties of electrode/electrolyte and decreasing the PEO crystallization, which were confirmed by XRD and SEM characteristics. The effects of polymer composition, nano SiO2 content on the ionic conductivity and I3- ions diffusion of polymer-blend electrolyte are investigated. The optimized composition yields an energy conversion efficiency of 3.71% under irradiation by white light (100 mW cm-2).

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Intergranular corrosion (IGC) resistance of types 304LN and 316LN stainless steels (SS) thermally aged at 823, 873, and 923 K for various durations was assessed by ASTM A262 practice A test (electrolytic etch test) and electrochemical potentiodynamic reactivation (EPR) test. The results indicated that the type 316LN SS has significantly improved IGC resistance compared to 304LN SS. Based on the results of these tests, time-temperature-sensitization (TTS) diagrams were developed for both alloys. The secondary precipitates formed during thermal aging treatments were electrochemically extracted and analyzed by X-ray diffraction (XRD) to determine the types of precipitates formed during the aging treatments. The results indicated that the precipitates were mostly of M_2_3C_6 carbides.

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In situ synthesis of silver chloride (AgCl) nanoparticles was carried out under ambient conditions in nanoporous bacterial cellulose (BC) membranes as nanoreactors. The growth of the nanoparticles was readily obtained by alternating dipping of BC membranes in the solution of silver nitrate or sodium chloride followed by a rinse step. X-ray diffraction (XRD) patterns indicated the existence of AgCl nanoparticles in the BC and scanning electron microscopy (SEM) images showed that the AgCl nanoparticles well dispersed on the surface of BC and penetrated into the BC network. The AgCl nanoparticle-impregnated BC membranes exhibited high hydrophilic ability and strong antimicrobial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). The preparative proced...

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Single crystals of ytterbium tartrate trihydrate have been grown by gel method using silica and agar-agar gels as media of growth. The medium of growth influences the morphology of grown crystals, silica gel yielding single and polycrystalline in the form of spherulites whereas agar-agar gel leading to growth of single and twinned crystals. Materials grown as single crystals have been characterized by using optical and scanning electron microscopy (SEM), EDAX, XRD, FT-IR, CHN and thermogravimetric techniques. The stoichiometry of the grown single crystals is suggested to be Yb(C4H4O6) (C4H5O6).3H2O. The FT-IR spectrum shows the presence of singly as well as doubly ionized tartrate ligands. Results of thermal analysis indicate that the material is thermally stable up to a temperature of 200...

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Phase transformations from #alpha#- to #beta#-SiAlONs (i.e., from #alpha#' to #beta#') have been recently reported in a number of rare-earth SiAlON systems during postsintering heat treatment. In the present work, this transformation process in a Sm (#alpha# + #beta#)-SiAlON material is studied by using XRD, TEM, and EDS X-ray mapping techniques. It is observed that in addition to the formation of #beta#' and M' phases, the #alpha#'-to-#beta#' transformation is accompanied by a significant increase in the amount of an AlN-polytypoid phase. The results suggest that some #alpha#' phases are thermodynamically unstable at temperatures lower than the material sintering temperature and will decompose when conditions allow. For the composition studied in this work, the #alpha#-SiAlON decomposition can be described in general as #alpha#' #-># #beta#' + M' + AlN polytypoid.

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Pd/Ag alloy hollow spheres have been synthesized in ethylene glycol solution by the solvothermal method and have been characterized extensively. TEM results have revealed the formation of Pd/Ag hollow spheres. Moreover, HRTEM results confirmed the formation of Pd/Ag alloy spheres, where the lattice fringe spacing is 0.229 nm corresponding to the (111) plane of Pd/Ag alloy. SEM, XRD and UV-vis results have further suggested the formation of alloy hollow spheres. The preliminary results showed the reaction time may be an importance factor influencing the formation of Pd/Ag alloy hollow spheres.

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Ferroelectric [Pb_0_._9_2(La_1_-_zSb _z)_0_._0_8][Zr_0_._6_0Ti_0_._4_0]O_3 for z = 0.0, 0.3, 0.6, 0.9 and 1 were prepared from their constituent oxides by a solid state reaction technique. The powders were calcined in the temperature range of 1000 deg. C for 6 h. Phase formation, crystal structure and lattice parameter were investigated by X-ray diffraction (XRD) technique. The compacts were sintered at 1250 deg. C for 2 h and their dielectric, ferroelectric and conductive properties were measured. The ferroelectric behavior of the doped samples was studied from their hysteresis loop.

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Recent research carried out in laboratories showed that Saddle field neutral fast atom beam source is a promising method for nitriding of stainless steel. In the present work, the effect of treatment time on the microstructural and mechanical properties of plasma-nitrided stainless steel sample was investigated by this new method. Plasma nitriding was carried out at 420 deg. C and at a pressure of 0.1 Pa for a time range of 1 to 12 h. SEM-EDX, microhardness tests, optical microscopy and X-ray diffraction (XRD) were used to evaluate the mechanical and structural properties of the nitrided layer. It was found that nitriding time has a pronounced effect on the structural and mechanical properties of low-temperature plasma-nitrided samples and produced a precipitation-free thin hard nitrided layer within a short processing time.

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TiB{sub 2} appears to be a promising material for the wear protection in various tribological systems, e.g. the diecasting of Al. This study focuses on the development of titanium boride coatings deposited by PACVD, a deposition method which is most suitable for the coating of substrates with complex shapes. All layers analysed are very smooth and exhibit a quasi-amorphous fracture surface. XRD and TEM analysis indicate a nanocrystalline structure with grain sizes in the order of 2 nm. The diffraction patterns can well be correlated to titanium diboride. WDS reveals an over stoichiometric B/Ti ratio. The layer hardness reaches the value of 33 GPa and the critical load in scratch tests rises to 35 N. Neither 100Cr6 nor Al as a counterpart in pin-on-disk tests leads to wear of the coating. (orig.)

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Industrial solid wastes (fly ash and red mud, a by-product of the aluminium industry) have been employed as supports for preparation of Ru-based catalysts. Physical and chemical treatments on red mud were conducted and these modified supports were also used for preparation of Ru-based catalysts. Those Ru catalysts were characterized by various techniques such as N2 adsorption, H{sub 2} adsorption, XRD, XPS, and temperature-programmed reduction (TPR), and were then tested for catalytic ammonia decomposition to hydrogen. It was found that red-mud-supported Ru catalyst exhibits higher ammonia conversion and hydrogen production than fly-ash-supported catalyst. Heat and chemical treatments of the red mud greatly improve the catalytic activity. Moreover, a combination of acid and heat treatments produces the highest catalytic conversion of ammonia. 35 refs., 4 figs., 4 tabs.

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Bio-inspired palladium nanoparticles were synthesized by using banana peel extract (BPE), a non-toxic eco-friendly material. Boiled, crushed, acetone precipitated, air-dried peel powder was used to reduce palladium chloride. The palladium nanoparticles were characterized by using UV-Visible spectroscopy, scanning electron microscope-energy dispersive spectra (SEM-EDS) and X-ray diffraction (XRD) analysis. Dynamic light scattering (DLS) studies revealed the average size of nanoparticles to be 50nm. Fourier transform infra red spectroscopy (FTIR) implicated the role of carboxyl, amine and hydroxyl groups in the synthetic process. This paper thus describes a novel green method for the synthesis of palladium nanoparticles.

British Library Electronic Table of Contents (United Kingdom)

In this study a novel sol-gel auto-combustion method, using n-decyltrimethylammonium bromide as a cationic surfactant, has been used to synthesize strontium hexaferrite nanocrystalline powder. The dried nitrate-citrate gel, prepared from a solution of ferric nitrate, strontium nitrate, citric acid, trimethylamine and cationic surfactant, exhibited an auto-combustion behavior after ignition in air. The formation reaction temperature, phase identification, crystallites size, particles size distribution and morphology of resultant strontium hexaferrite powder were investigated by DTA/TGA, FTIR, XRD, LPSA, TEM and SEM techniques. The results showed that in presence of the cationic surfactant, the combustion intensity increases and the crystallite size decreases. The crystallite size of stronti...

International Nuclear Information System (INIS)

This paper reports on a series of experiments performed to examine the ability of ion beam assisted thermal deposition to produce good adhesion of Au metallization on GaAs left-angle 100 right-angle substrates. A study of the influence of Ar ion-assisted thermal deposition of the Au films as well as in situ pre-sputtering of the GaAs surface with low-energy Ar ions prior to thermal deposition, shows that strong adhesion can be achieved without resorting to chemical cleaning. The substrate temperature and the relative flux of Ar ions to incident Au atoms were varied in order to correlate these parameters with film adhesion. The interfaces of films processed under these various conditions were examined by XTEM, RBS and XPS. Orientation texture was studied by x-ray diffraction (XRD).

Energy Technology Data Exchange (ETDEWEB)

Silicon thin film with thickness in range 1000-5300 A deposited on rough Cu foil by a radio frequency magnetron sputtering is used as anode materials for Li-ion rechargeable batteries. The SEM, XRD and TEM analysis reveals that the Si thin film has a floccular nano-sized multi-crystalline structure. Li ions insertion/extraction evaluation is performed mainly with constant current charge/discharge cycling and cyclic voltammetry (CV) at room temperature. The cycleability and reversible discharge capacity are found to depend on the film thickness, and thinner films give larger accommodation capacity. A 3120 A Si film provides a reversible specific capacity over 3500 mA hg{sup -1} with excellent cycleability under 0.5 C charge/discharge rate.

Science.gov (United States)

The present study attempts to use hydrogen peroxide solution to humidify Ca(OH)(2) particles to enhance the absorption of SO(2) to achieve higher removal efficiency and to solve the valuable reuse of the reaction product in the semidry flue gas desulfurization (FGD) process. Experiments were carried out to examine the effect of various operating parameters including hydrogen peroxide solution concentration, Ca/S molar ratio and approach to adiabatic saturation temperature on SO(2) removal efficiency in a laboratory scale spray reactor. The product samples were analyzed to obtain semi-quantitative measures of mineralogical composition by X-ray diffraction (XRD) with reference intensity ratio (RIR) method and the morphology of the samples was examined by scanning electron microscope (SEM). Compared with spraying water to humidify Ca(OH)(2), SO(2) removal efficiency was improved significantly by spraying hydrogen peroxide solution of 1-3 wt.% to humidify Ca(OH)(2) ...

International Nuclear Information System (INIS)

In this work, ZnO thin films have been grown on glass substrates by using a solution of propanol (C3H8O), water (H2O) and zinc acetate (Zn(CH3CO2)2) in acidified medium (pH 5). The obtained films were n doped with ytterbium (Yb) at the rates of 100, 200 and 300 ppm. The structural features of the doped films were investigated using XRD, atomic force microscopy and scanning electronic microscopy techniques. XRD analysis shows a strong (0 0 2) X-ray diffraction line for increasing Yb-doping amounts. This c-axis preferential orientation of ZnO crystallites is naturally required to use this oxide as transparent conductor in optoelectronic applications. Atomic force microscopy (AFM) analysis shows an enhancement in the surface roughness of the doped ZnO:Yb thin films. Optical measurements were performed in 300-1800 nm domain via transmittance T(?) and reflectance R(?) spectra. Conjoint optical and thermal properties were deduced from the optical ...

International Nuclear Information System (INIS)

The effect of severe plastic deformation by cold high pressure torsion (HPT) on radio frequency (RF) plasma nitriding of pure iron, as well as St2K50 and X5CrNi1810 steels was investigated. Nitriding was carried out for 3 h in a nitrogen atmosphere at a pressure of 10"-"5 bar and temperatures of 350 and 400 deg. C. Nitrided specimens were analysed by scanning electron microscopy (SEM), X-ray diffraction and micro hardness measurements. It was found that HPT enhances the effect of nitriding leading almost to doubling of the thickness of the nitrided layer for pure iron and the high alloyed steel. The largest increase in hardness was observed when HPT was combined with RF plasma nitriding at 350 deg. C. In the case of pure iron, the X-ray diffraction spectra showed the formation of #epsilon# and #gamma#' nitrides in the compound layer, with a preferential formation of #gamma#' at the expense of the #alpha#-phase at the higher nitriding temperature. The corresponding surface hardness was ...

DEFF Research Database (Denmark)

Zinc oxide (ZnO) and alumina (Al2O3) particles are synthesized by the combustion of their volatilized acetylacetonate precursors in a premixed air-methane flame reactor. The particles are characterized by XRD, transmission electron microscopy, scanning mobility particle sizing and by measurement of the BET specific surface area. Pure (?-)alumina particles appear as dendritic aggregates with average mobile diameter 43-93 nm consisting of partly sintered, crystalline primary particles with diameter 7.1-8.8 nm and specific surface area 184-229 m2/g. Pure zinc oxide yields compact, crystalline particles with diameter 25-40 nm and specific surface area 27-43 m2/g. The crystallite size for both oxides, estimated from the XRD line broadening, is comparable to or slightly smaller than the primary particle diameter. The specific surface area increases and the primary particle size decreases with a decreasing flame temperature and a decreasing precursor ...

International Nuclear Information System (INIS)

The beta transformation characteristics and mechanical properties of the #beta# titanium alloy Ti_5_0Zr_3_0Nb_1_0Ta_1_0 in the temperature range between 200 and 900 deg. C have been studied by means of X-ray diffraction (XRD), Vickers hardness (HV), and tensile test techniques. In the as-rolled state, only #beta#-phase was identified by XRD. Upon heat-treating at 250 deg. C for 4 h, the #alpha#-phase was precipitated from the #beta#-phase matrix, and leading to an increase of Vickers hardness. A maximum HV value was observed at 400 deg. C, and then HV value decreased with increasing heat-treating temperature. Above 650 deg. C, HV value remained almost constant. During heat-treating at 300-650 deg. C, the decomposition of the metastable #beta#-phase has been found to proceed through a phase separation reaction leading to the formation of #beta#-Ti and #beta#-Zr b.c.c. solid solution phases rather than the formation of solute rich and solute lean ...

International Nuclear Information System (INIS)

The transmutation of minor actinides in-reactor is one solution currently being studied for the long time management of nuclear waste. In the heterogeneous concept the radionuclides are incorporating in an inert ceramic matrix. The support material must be insensitive to radiation damage. Fission product damage is the main radiation damage source during the transmutation process and therefore it is of the utmost importance to study their effects. We irradiated spinels MgAl_2O_4 (matrix of reference) and ZnAl_2O_4 by fast ions (by example: (86)Kr of approximately 400 MeV) simulating the fission products. Under these conditions, the damage is primarily due to the electronic energy losses (Se). One of the structural features of spinel AB_2O_4 is that the two cations (A(2+) and B(3+)) can exchange their site. This phenomenon is quantified by the inversion parameter. We highlight by XRD in grazing incidence that the structural changes observed in MgAl_2O_4 correspond to ...

Energy Technology Data Exchange (ETDEWEB)

Fe{sub x}Zn{sub 1-x} alloys were electrochemically deposited on aluminum substrates from a sulfate bath. The K{beta}/K{alpha} x-ray intensity ratios of Zn and Fe in Fe{sub x}Zn{sub 1-x} thin films have been experimentally studied. The energy dispersive x-ray fluorescence (EDXRF) technique was used to measure K x-ray photons. Samples were excited by using 59.5 keV photons emitted by a 50 mCi {sup 241}Am radioactive source. The emitted K x-rays were detected by an Ultra-LEGe detector having a resolution of 150 eV at 5.9 keV. In addition, the effect of bath composition on the phase structure was investigated by x-ray diffraction (XRD) analysis. The composition of the thin films was analyzed by atomic absorption spectrometry analysis. Iron content was shown to strongly affect the structure of Zn-Fe alloys. It was found that the K-shell x-ray intensity ratio changed in Fe{sub x}Zn{sub 1-x} thin films for different values of x. The reason for this change may be that the ...

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The possibilities to electrodeposit thick coatings composed of nanoparticles of Sb and Sb{sub 2}O{sub 3} for use as high-capacity anode materials in Li-ion batteries have been investigated. It is demonstrated that the stability of the coatings depends on their Sb{sub 2}O{sub 3} concentrations as well as microstructure. The electrodeposition reactions in electrolytes with different pH and buffer capacities were studied using chronopotentiometry and electrochemical quartz crystal microbalance measurements. The obtained deposits, which were characterised with XRD and SEM, were also tested as anode materials in Li-ion batteries. The influence of the pH and buffer capacity of the deposition solution on the composition and particle size of the deposits were studied and it is concluded that depositions from a poorly buffered solution of antimony-tartrate give rise to good anode materials due to the inclusion of precipitated Sb{sub 2}O{sub 3} nanoparticles in the Sb ...

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In this paper nickel acetate catalyzed sodium borohydride cartridges have been prepared and hydrolyzed with water for hydrogen production. Two technological solutions have been tested to increase the overall hydrogen yield, namely a porous water diffuser and a hydrophobic membrane. The first was used to improve water diffusion inside the hydride while the second to confine water inside the cartridge. The generated hydrogen flow showed a very reproducible behavior. Hydrogen promptly evolved just after water was pumped into the cartridge. After some initial peaks, a constant hydrogen flow has been recorded for the whole reaction time. The constant flow was related to the presence of the porous diffuser. The use of a hydrophobic membrane to confine the water inside the cartridge allowed to increase the overall hydrogen yield: about 6 water molecules per mol of hydride were required to complete the reaction. The reaction product was identified by XRD as Na{sub 2}B{sub ...

Energy Technology Data Exchange (ETDEWEB)

The elemental and mineralogical variation in a self-burning coal seam from Coalspur, Alberta, is determined using instrumental neutron activation analysis (INAA) and x-ray diffraction (XRD). The elemental variation in the coal seam is related to temperatures in the various alteration zones, i.e., oxidation, combustion, or carbonization and nature of elements. Mobilization of elements is greatest for As, Br, Cl, Mo, N, S, and Sb. Some of these elements are released to the atmosphere, as evident by the presence of orthorombic sulfur crystals on the surface or in vents at the top of the burning seam or saturation of oxidation char by volatile matter (tar). Whewellite (CaC{sub 2}O{sub 4}, H{sub 2}O) is the only Ca-bearing mineral found in the cooler area of the coal seam. Decomposition of this mineral, coupled with the presence of SO{sub 2} formed by reaction of organic sulfur with O{sub 2} in combustion, resulted in formation of a relatively high gypsum content in the ...

Energy Technology Data Exchange (ETDEWEB)

In the present paper the tribological behavior of the coatings are discussed. Duplex coatings were applied on cold working steel 100Cr6. Samples were plasma nitrided at different thickness of plasma surface layers. TiN was deposited with a classic BALZERS PVD equipment and subsequent ion implantation. Ion implantation was provided with N{sup 5+} ions. The other samples were produced with IBAD technology in DANFYSIK chamber. Wear resistance and exchanges of friction coefficient were measured with on-line test using special designed tribology equipment. Following the tests, the wear zone morphology and characteristics of surface layer structure as well as important properties were investigated by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Scratch adhesion testing was performed using commercially available equipment. Energy dispersive X-ray analysis (EDAX) of the wear-scars on pins provided essential information on the wear ...

Energy Technology Data Exchange (ETDEWEB)

This work presents a comparative study of low-alloy steel nitriding for different possible techniques. Active screen plasma nitriding (ASPN) is a successful surface modification method that has many advantages over the conventional DC plasma nitriding (CPN). The corrosion behavior of 30CrNiMo8 low-alloy steel has been examined using anodic polarization tests in 3.5% NaCl solution under varying conditions of ASPN and CPN processes. The process variables included active screen setup parameters, treatment temperature (550 and 580 deg. C), gas mixture (25/75 and 75/25 of N{sub 2}/H{sub 2}) and treatment time (5 and 10 h) in 500 Pa pressure. The structure and phases composition of the compound layer was studied by X-ray diffraction (XRD), microhardness tests, optical microscopy and scanning electron microscopy (SEM). It was observed that ASPN treated samples surface enhanced corrosion resistance while the temperature and/or hole size of screen setup increased.

International Nuclear Information System (INIS)

The effect is reported of seven inorganic oxide additives on both the formation mechanism and the densification of X-Sialon prepared by a silicothermal process. The oxides were added to the starting mixture of halloysite clay, alumina and elemental silicon at a level of 1 wt% of the calculated final product, and fired in nitrogen at 1200-1500 deg C. The formation of X-Sialon was monitored by thermal analysis, powder XRD and 2"7"Al and "2"9Si solid state MAS NMR The effects of the additives are temperature dependent and influence the various stages of the reaction by differing degrees. The oxides which best promote the formation of crystalline X-Sialon (Y_2O_3, CaO and MgO) are also those which facilitate the conversion of initially-formed Si_3N_4 to SiO_2N_2 and SiO_3N units. Densification is most enhanced by Y_2O_3 CaO and CeO_2; MgO exerts its maximum effect on sintering at lower temperatures. Copyright (1998) Australasian Ceramic Society

Energy Technology Data Exchange (ETDEWEB)

Several types of coatings have previously been visually identified on the surface of 105-K East and 105-K West Basins fuel elements. One type of coating (found only in K West Basin) in particular was found to be a thick translucent material that was often seen to be dislodged from the elements as flakes when the elements were handled during visual examinations (Pitner 1997). Subsequently it was determined (for one element only in a hot cell) that this material, in the dry condition, could easily be removed from the element using a scraping tool. The coating was identified as Al(OH){sub 3} through X-ray diffraction (XRD) analyses and to be approximately 60 {micro}m thick via scanning electron microscopy (SEM). However, brushing under water in the basin using numerous mechanical strokes failed to satisfactorily remove these coatings in their thickest form as judged by appearance. Such brushing was done with only one type of metal brush, a brush design previously ...

International Nuclear Information System (INIS)

In this study nanocrystalline powders of yttria-stabilized zirconia (ZrO_2-8Y_2O_3) have been synthesized through 'polymerized complex method'. Zirconium chloride, yttrium nitrate, citric acid and ethylene glycol were polymerized at 80 "oC to produce a gel-like mass in which metallic ions were uniformly distributed. During the thermal treatment of dried gel, nanocrystalline powder was formed at 450 "oC and 650 "oC for 2 h. Thermal reactions and crystalline phase formation of the dried gel were investigated through thermal analysis and X-ray diffraction analysis, respectively. The results of thermal analysis and XRD showed the formation of nanocrystalline powder at less than 600 "oC. Chemical bonding of the dried gel was investigated by Fourier transform infrared spectroscopy analysis. Morphology of powder calcined at 650 "oC was analyzed by scanning electron microscope. Yttria-stabilized zirconia powders with the mean crystallite size of 6 nm were prepared ...

Energy Technology Data Exchange (ETDEWEB)

Crystalline MnV{sub 2}O{sub 6} has been synthesized by a polymer gellation method and investigated for its physical and electrochemical properties as an anode material for Li secondary battery. The physical characterization was carried out by thermal analysis (TG/DTA), FT-IR and SEM. Structural analysis by powder XRD and spectroscopic analysis by XANES showed that the synthesized compound is MnV{sub 2}O{sub 6} with brannerite structure. The Li insertion of MnV{sub 2}O{sub 6} anode during the first charge showed a large capacity of about 1400 mAh/g, accompanied by irreversible structural transformation into amorphous material. Despite its structural transformation to amorphous during the first lithiation, subsequent cycles showed a capacity of about 800 mAh/g. This paper presents the advantage of this material over existing anode material and discusses the mechanism underlying the electrode process.

International Nuclear Information System (INIS)

Fine ceramic particles of zirconia toughened alumina (ZTA), titania toughened alumina (TTA), and zirconia-titania toughened alumina (ZTTA) have been synthesized by ultrasonic spray pyrolysis (USP) at various temperatures from starting salt solutions of various compositions aiming for the development of catalytic material. These particles were characterized for properties such as shape, size and size distribution, diffraction pattern, and chemical and phase composition of elements by scanning electron microscopy (SEM), particle size analyzer (PSA), x-ray diffraction (XRD), and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Chemical compositions and sizes of ceramic composites have been controlled by the stoichiometry of salt solutions and the flow rate of spraying solutions. The optimum experimental conditions for the various composite particle synthesis have been proposed.

Energy Technology Data Exchange (ETDEWEB)

The NiO-samaria doped ceria (SDC) composite powders were prepared by spray pyrolysis technique at temperatures between 400 and 1000 C. The variation of the particle structure was investigated by X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), scanning electron microscope (SEM), and transmission electron microscope (TEM)-energy-dispersive X-ray spectroscopy (EDS). The thermal analysis of raw materials was also carried out. The following facts became clear in this study. Ceria and nickel have been already separated at 400 C. Samaria is amorphous phase below 600 C, and is dissolved in ceria at 600 C or higher. Samaria is distributed uniformly inside the particles before dissolving in ceria. The thermal decomposition temperatures of metal nitrate are: cerium < nickel < samarium. The results of these analyses were explained without contradiction. It was found that it is important to optimize the state of liquid drop before thermal ...

Energy Technology Data Exchange (ETDEWEB)

In this study, WO{sub 3} thin films were grown on glass substrates using an aqueous solution containing tungstate (NH{sub 4}){sub 2}WO{sub 4} as precursor. The substrate temperature incremented from 250 to 500 deg. C, by steps of 50 deg. C. The structural properties were investigated using XRD, atomic force microscopy and scanning electronic microscopy techniques. Microprobe analyses showed that a balanced stoichiometric composition was obtained for thin films prepared at T{sub s} = 350 and 400 deg. C. The X-ray diffraction analyses showed different structure crystallography in function of the substrate temperature. Moreover, films deposited at 400 deg. C were annealed in air for 2 h at 450 and 500 deg. C, respectively and the structural changes due to heat treatment were studied. Finally, the optical properties of these films were carried out using optical measurements of transmittance T({lambda}) and reflectance R({lambda}) spectra in 300-1800 nm domain. The ...

International Nuclear Information System (INIS)

We have developed a chemical process for incorporating copper into indium gallium selenide layers with the goal of creating a precursor structure for the formation of copper indium gallium diselenide (CIGS) photovoltaic absorbers. Stylus profilometry, EDX, Raman spectroscopy, XRD and SIMS measurements show that when indium gallium selenide layers are immersed in a hot copper chloride solution, copper is incorporated as copper selenide with no increase in the thickness of the layers. Further measurements show that annealing this precursor structure in the presence of selenium results in the formation of CIGS and that the supply of selenium during the annealing process has a strong effect on the morphology and preferred orientation of these layers. When the supply of Se during annealing begins only once the substrate temperature reaches ? 400 deg. C , the resulting CIGS layers are smoother and have more pronounced preferred orientation than when Se is supplied ...

International Nuclear Information System (INIS)

A series of Gd-substituted M-type barium hexaferrites has been prepared by the ceramic route, according to the formula (Ba_1_-_xGd_x)O.5.25Fe_2O_3 (x=0-0.30). XRD analysis revealed that all the samples present primarily an M-type structure. Samples x=0 and x=0.05 are single-phase. Hematite (Fe_2O_3) and GdFeO_3 were detected in the remaining samples. Coercivity (H_c) shows remarkably high values, #approx#293kA/m for x=0.20 and 0.30 with a maximum of 322kA/m for x=0.25. Specific saturation magnetization (#sigma#_s_a_t) of the samples presents a small increase up to x=0.10. The microstructure examination indicates that Gd may act as a grain growth inhibitor.

British Library Electronic Table of Contents (United Kingdom)

TaC and TaC-1wt.% B4C powders were consolidated using spark plasma sintering (SPS) at 1850^oC and varying pressure of 100, 255 and 363MPa. The effect of pressure on the densification and grain size is evaluated. The role of nano-sized B4C as sintering aid and grain growth inhibitor is studied by means of XRD, SEM and high resolution TEM. Fully dense TaC samples were produced at a pressure of 255MPa and higher at 1850^oC. The increasing pressure also resulted in an increase in TaC grain size. Addition of B4C leads to an increase in the density of 100MPa sample from 89% to 97%. B4C nano-powder resists grain growth even at high pressure of 363MPa. The formation of TaB2/Carbon at TaC grain boundaries helps in pinning the grain boundary and inhibiting grain growth. The effect of B4C addition on...

International Nuclear Information System (INIS)

In this study, SnO2 thin films have been grown using spray pyrolysis technique on glass substrates under a substrate temperature (Ts = 440 oC). The precursors were methanol CH4O and anhydrous tin tetrachloride. XRD analyses yielded strong (1 1 0)-(1 0 1)-(2 0 0) X-ray diffraction peaks which are characteristics to tetragonal crystals. Atomic Force Microscopy (AFM) analyses showed the existence of clusters with particular pyramidal shapes. The main part of this study concerns the optical measurements of transmittance T(?) and reflectance R(?) spectra inside 250-1800 nm domain. Conjoint optical and thermal properties were deduced using the Amlouk-Boubaker Opto-Thermal Expansivity ?AB. The obtained value: ?AB ? 23.4 m3 s-1 helped situating the performance of the as-grown SnO2 compound among most known PV-T oxides like ZnO and TiO2.

International Nuclear Information System (INIS)

A series of silylated Co/SBA-15 catalysts were prepared via the reaction of surface Si-OH of SBA-15 with hexamethyldisilazane (HMDS) under anhydrous, vapor-phase conditions, and then characterized by FT-IR, N2 physisorption, TG, XRD, and TPR-MS. The results showed that organic modification led to a silylated SBA-15 surface composed of stable hydrophobic Si-(CH3)3 species even after calcinations and H2 reduction at 673 K. Furthermore, the hydrophobic surface strongly influenced both metal dispersion and reducibility. Compared with non-silylated Co/SBA, Co/S-SBA (impregnation after silylation) showed a high activity, due to the better cobalt reducibility on the hydrophobic support. However, S-Co/SBA (silylation after impregnation) had the lowest FT activity among all the catalysts, due to the lower cobalt reducibility along with the steric hindrance of grafted -Si(CH3)3 for the re-adsorption of ?-olefins. -- Graphical abstract: The silylation of an SBA-15 before ...

Energy Technology Data Exchange (ETDEWEB)

Crystalline MnMoO{sub 4} was synthesized using a conventional solid reaction method and investigated for its physical and electrochemical properties as an anode material for Li secondary battery. The reversible amount of Li insertion/removal of MnMoO{sub 4} anode during the first cycle was about 800 mA h/g, accompanied by irreversible structural transformation into amorphous material. The amorphization during the first Li insertion was investigated by structural analysis using XRD of electrode. The charge compensation during Li insertion/removal was examined by measurement of X-ray Absorption Near Edge Structure (XANES) spectroscopy. Despite its irreversible structural transformation to amorphous during the first lithiation, subsequent cycles showed a reasonable cyclability. This paper presents the electrochemical properties of MnMoO{sub 4} and discusses the mechanism underlying the Li insertion/removal process.

International Nuclear Information System (INIS)

The aim of this work is to describe the processes during plasma nitriding of Nb-containing, powder metallurgy prepared (PM) tool steel. PM steel was studied containing 2.5% C, 3.3% Si, 6.2% Cr, 2.2% Mo, 2.6% V, 2.6% Nb and 1.0% W, produced by melt atomization and hot isostatic pressing. The hardened and tempered steel was plasma nitrided at temperatures ranging from 470 to 530 deg. C. The nitriding time was 30-180 min. Optical microscopy, electron microscopy, XRD, EDS, WDS and hardness measurements were used to study the steel's properties, microstructure, phases and chemical composition. The nitriding temperature of 470 deg. C was found to be unsuitable for practical use because the layers prepared at this temperature were non-uniform. The compound layer formed by M_2_,_3(C,N) and M_4N was found after nitriding at temperatures of 500 and 530 deg. C for at least 60 min. The effect of niobium on the formation of this layer was studied.

International Nuclear Information System (INIS)

Thermochromic tungsten-doped vanadium dioxide (VO2) powders were successfully synthesized by thermal reduction using V2O5 as a vanadium precursor. The products were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The results indicated that W was successfully doped into the crystal lattice of VO2 matrix, and prepared tungsten-doped VO2 had a rod-like morphology. The effects of reducing temperature and annealing temperature on the crystallographic structures were also discussed. The phase transition temperature (Tt) of VO2 could be simply tuned by changing the doping concentration of tungsten. When the doping concentration was 1.58 mol%, the Tt could be reduced to 37.8 oC from initial 69.5 oC, suggesting that tungsten-doped VO2 possesses prominent thermochromic properties and optical switching characters. It has shown that this convenient and efficient ...

Energy Technology Data Exchange (ETDEWEB)

This paper introduces a new method to produce nano-composite powder for the preparation of high performance ZnO varistors. ZnO particles were coated with Bi{sub 2}O{sub 3}, Sb{sub 2}O{sub 3}, Co{sub 2}O{sub 3}, Cr{sub 2}O{sub 3} and other additives via liquid nano-coating technique. Then the prepared powder was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravity and differential scanning calorimetry (TG-DSC) and particle size distribution. The results showed that the ZnO composite powder is homogeneously coated and ultrafine. The densification, phase composition and microstructure of ZnO varistors was studied by linear shrinkage, X-ray diffraction (XRD) and SEM, respectively. The preliminary electrical parameters of ZnO varistors showed that the breakdown voltage V {sub b} (1 mA/cm{sup 2}) and nonlinear coefficient {alpha} is 5400 V/cm and 50, respectively, much higher than that of conventional ball milling ...

Energy Technology Data Exchange (ETDEWEB)

The Co-doped BaTiO{sub 3} nanosized powders and ceramics were prepared via the sol-gel process. The powders and ceramics were characterized by methods of XRD, SEM and TEM. The dielectric properties of the ceramics were also determined by these methods. The influence of sintering temperature, sintering time and Co concentration on the microstructure and dielectric properties was discussed. The results revealed that the powders were in nanometer scale (30-50 nm) and were mainly composed of cubic BaTiO{sub 3} phase and small amount of BaCO{sub 3}. After sintering, both the cubic BaTiO{sub 3} and BaCO{sub 3} were transformed into tetrahedron BaTiO{sub 3}. The sintering temperatures of the Co-doped BaTiO{sub 3} ceramics decreased (about 100 deg. C) and the Curie temperatures of the ceramics were then moved to lower temperature. In addition, the dielectric constant of the ceramics doping with Co was higher than that of the pure BaTiO{sub 3} ceramics. The dielectric ...

International Nuclear Information System (INIS)

The pozzolanic behaviour of compound-activated red mud-coal gangue has been investigated through TG, DTA, XRD, FTIR and 27Al MAS NMR. From viewpoint of reaction kinetics, it is found that the pozzolanic reaction mechanism of the compound-activated red mud-coal gangue - lime system is clearly consistent with diffusion control up to 14 days, and the reaction rate constant calculated from Jander equation decreases with the increase of CaO addition in the system. The hydration products formed in the red mud-coal gangue - lime systems at ambient temperature are essentially aluminous C-S-H and Ca3Al2O6.xH2O. From TG analysis results, it is thought that the high amount of Ca(OH)2 in the pastes of studied system is not conducive to the continual increase of non-evaporable water content of the hydration products. Of particular interest, 27Al MAS NMR proved to be an effective technique to obtain valuable information of Al[4] in C-S-H and Al[6] in Ca3Al2O6.xH2O.

Science.gov (United States)

Continuous metallic glass ribbons were produced by mejans of liquid-quenching at rates >10/sup 50/C/s. The ribbons, typically 30 ..mu..m thick and 1 to 2 mm wide, were determined to be glassy by X-ray diffraction (XRD) employing CuK..cap alpha.. and MoK..cap alpha.. radiation. Mechanical properties of the as-quenched product were determined by measurements of hardness, tensile strength and Young's modulus. The Vicker's diamond pyramid microhardness (H/sub V/) was measured on epoxy mounted samples using a Lietz Miniload instrument with a 100 g load. Tensile tests were conducted in an Instron machine using specimens which were hand-polished to produce smooth, parallel sides. Young's modulus (E) is given by the relationship rho V/sub E/sup 2//. V/sub E/, the velocity of extensional mode waves, was measured by the pulse-echo technique using a Panametrics Intervalometer and glass density, rho, was obtained by the liquid immersion method. ...

British Library Electronic Table of Contents (United Kingdom)

A series of new non-discoid chiral copper(ii)-salen type complexes, [Cu((4-CnH2n+1O)2salen)], n = 14, 16, 18 and salen = N,N'-cyclohexane bis (salicylideneiminato), containing 4-substituted alkoxy tails in the side aromatic rings and a cyclohexane spacer, have been prepared and their mesogenic properties investigated. The compounds were characterised by Fourier transform infra-red spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy, UV-vis spectroscopy and fast atom bombardment mass spectrometry. Mesomorphic properties of these compounds were studied by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction (XRD). The ligands are non-mesogenic but the complexes exhibited enantiotropic rectangular columnar mesophases (Colr) with extended temperat...

International Nuclear Information System (INIS)

Ordered mesoporous C-TiO2 nanocomposites with crystalline framework were prepared by the evaporation-induced triconstituent co-assembly method. The products were characterized by XRD, TEM, N2 adsorption-desorption and TG. Their microwave absorption properties were investigated by mixing the product and epoxy resin. It is found that the peak with minimum reflection loss value moves to lower frequencies and the ordered mesoporous C-TiO2 nanocomposite possesses an excellent microwave absorbing property with the maximum reflection loss of -25.4 dB and the bandwidth lower than -10 dB is 6.6 GHz. The attenuation of microwave can be attributed to dielectric loss and their absorption mechanism is discussed in detail. The mesoporous C-TiO2 nanocomposites also exhibit a lower infrared emissivity in the wavelength from 8 to 14 ?m than that of TiO2-free powder. -- Graphical abstract: Ordered mesoporous C-TiO2 nanocomposite with crystalline framework possess excellent microwave ...

Science.gov (United States)

A number of agricultural and engineering uses for fixated flue gas desulfurization (FGD) material exist; however, the potential for leaching of hazardous elements has limited widespread application and the processes controlling the leaching of this material are poorly understood. In this study, a flow-through rotating-disk system was applied to elucidate the relative importance of bulk diffusion, pore diffusion, and surface chemical reaction in controlling the leaching of fixated FGD material under pH conditions ranging from 2.2 to 6.8. Changing the hydrodynamics in the rotating disk system did not affect the leaching kinetics at both pH 2.2 and 6.8, indicating that bulk diffusion was not the kinetic-limiting step. Application of the shrinking core model (SCM) to the data suggested a surface reaction-controlled mechanism, rather than a pore diffusion mechanism. The leaching of fixated FGD material increased with decreasing pH, suggesting it can be described by a combination of an ...

Energy Technology Data Exchange (ETDEWEB)

Influence of residual K{sup +} on the preferential oxidation of CO in excess hydrogen (PROX) over CuO-CeO{sub 2} catalysts was investigated. CuO-CeO{sub 2} catalysts were characterized by BET, ICP, XRD, UV-Raman and TPR techniques. The results showed that the existence of residual K{sup +} made {alpha} peak in TPR of CuO-CeO{sub 2} catalysts shift to higher temperatures and depressed the PROX in the absence of CO{sub 2} and H{sub 2}O in the feed over CuO-CeO{sub 2} catalysts. However, small amount of residual K{sup +} was beneficial to the catalytic performance of CuO-CeO{sub 2} catalysts in the PROX in the presence of CO{sub 2} and H{sub 2}O in the feed. Consequently, residual K{sup +} with an appropriate content was beneficial to improve the catalytic performance of CuO-CeO{sub 2} catalysts in the presence of CO{sub 2} and H{sub 2}O. (author)

British Library Electronic Table of Contents (United Kingdom)

A series of spinel Li4Ti5O12 samples were synthesized via a composite molten-salt method (CMSM) using the mixtures of LiCl and KCl with different L values (L is defined as the molar ratio of LiCl:KCl) as the reaction media. It is found that the melting point of the composite molten salt can effectively influence the formation of particles, and leads to different electrochemical performances of the as-prepare Li4Ti5O12. The investigations of X-ray diffraction (XRD), particle size distribution (PSD), Brunauer-Emmet-Teller (BET) surface area, and scanning electron microscopy (SEM) indicate that the as-prepared Li4Ti5O12 with L=1.5 is a pure phase, and has uniform homogeneous octahedral shape particles, rather narrow PSD, and high BET surface area. Electrochemical tests show that the optimized...

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The present article describes a novel synthesis route for nano-sized goethite ({alpha}-FeOOH) using hydrazine sulphate as an additive. The X-ray diffraction (XRD) peaks of synthesized powder matched well with those of {alpha}-FeOOH. Transmission electron microscopy (TEM) showed the particles of irregular shape in the range of 1-10 nm. Batch adsorption experiments for fluoride uptake were performed to study the influence of various experimental parameters such as contact time (10 min to 7 h), initial fluoride concentration (10-150 mg L{sup -1}), pH (2-11.6) and the presence of competing anions. The time data fitted well to pseudo-second-order kinetic model. The fluoride removal passed through broad maxima in pH ranges of 6-8. High adsorption capacity of 59 mg g{sup -1} goethite was obtained. The isothermic data fitted well to Freundlich model. The presence of other ions namely chloride and sulphate adversely affected fluoride removal. Fluoride from contaminated ...

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Alkaline fuel cells (AFCs) provide a less corrosive environment and can provide higher electrode reaction kinetics than proton exchange membrane fuel cells (PEMFCs). The alkaline media also allows for the replacement of platinum (Pt) based electrocatalysts with non-Pt electrocatalysts. Studies have shown that palladium (Pd) and silver (Ag) form a homogenous solid solution with a face-centred cubic structure within a large range of temperatures. This study described the results of an oxygen reduction reaction (ORR) on lead-silver (Pd-Ag) alloy electrodes in alkaline media. The reaction was compared with Pd and Ag electrodes. The alloys were synthesized as thin films using a sequential electroless deposition of Pd and Ag on stainless steel discs followed by an annealing procedure in an Ar stream. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to characterize catalyst structure, morphology, and ...

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LiFePO{sub 4} cathode materials with distinct particle sizes were prepared by a planetary ball-milling method. The effects of particle size on the morphology, thermal stability and electrochemical performance of LiFePO{sub 4} cathode materials were investigated. The ball-milling method decreased particle size, thereby reducing the length of diffusion and improving the reversibility of the lithium ion intercalation/deintercalation. It is worth noting that the small particle sample prepared using malonic acid as a carbon source achieved a high capacity of 161 mAh g{sup -1} at a 0.1 C rate and had a very flat capacity curve during the early 50 cycles. However, the big particle samples ({proportional_to}400 nm) decayed more dramatically in capacity than the small particle size samples ({proportional_to}200 nm) at high current densities. The improvement in electrode performance was mainly due to the fine particles, the small size distribution, and the increase in electronic conductivity as ...

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Different experimental measurements (Theology, granulometry, XRD) were carried out in order to study the main properties of bentonite suspensions in presence of anionic additives at different concentrations. These additives are: Sodium Dodecyl Sulfate (SDS) as surfactant, a flexible polymer (Sodium Carboxy Methyl Cellulose, CMC) and a semi-rigid polymer (Xanthan gum). It has been shown that the structural nature of anionic additive influences directly the mixtures viscoelastic and flow behavior. The steric effect of the surfactant modifies the Face-Edge interactions and yields changes of the mixtures rheological behavior at low deformation rates. Polymers act by coating each clay particle and prevent their agglomeration. Therefore, bentonite has no direct effect on the rheological behavior of the mixtures: the additives are responsible for the mechanisms of de-structuration and structure reorganization as well as the mixtures viscous and viscoelastic behavior. ...

International Nuclear Information System (INIS)

A wear-resistant nitrided layer was formed on a 304L austenitic stainless steel substrate by DC plasma nitriding. Effects of DC plasma nitriding parameters on the structural phases, micro-hardness and dry-sliding wear behavior of the nitrided layer were investigated by optical microscopy, X-ray diffraction, scanning electron microscopy, micro-hardness testing and ring-on-block wear testing. The results show that the highest surface hardness over a case depth of about 10 #mu#m is obtained after nitriding at 460 deg. C. XRD indicated a single expanded austenite phase and a single CrN nitride phase were formed at 350 deg. C and 480 deg. C, respectively. In addition, the S-phase layers formed on the samples provided the best dry-sliding wear resistance under the ring-on-block contact configuration test.

International Nuclear Information System (INIS)

The fundamental optical properties of dysprosium (Dy) doped strontium sulfide bulk samples for various dopant concentrations from 0.1 to 1.0 at.% were investigated by X-ray diffraction (XRD), electron paramagnetic resonance spectroscopy (EPR), room temperature photoluminescence (PL), photoluminescence excitation (PLE) and diffuse reflectance spectroscopy (DRS). Investigations by electron paramagnetic resonance yielded the state of Dy in the sample as Dy3+. An additional ESR line due to F+ center was observed. The PL emission spectrum consisted of several intense lines and a number of weaker ones which were identified as transitions between energy levels of Dy3+. The optimum doping concentration for maximum intensity was found to be 0.25 at.%. Blue shift of the absorption edge energy and red shift of the PLE spectrum were observed with increasing doping concentration. The former is due to Burstein-Moss (BM) effect and the latter is attributed due to the presence of ...

British Library Electronic Table of Contents (United Kingdom)

Phosphor material BaAl2O4:Eu2+, Dy3+ with varying compositions of Sr substitution were prepared by the solid-state synthesis method. The phosphor compositions were characterized for their phase and crystallinity by XRD, SEM and TEM. Photoluminescence (PL) properties were investigated measuring PL and decay time for varying Ba/Sr compositions. The PL results show the blue shift in the luminescence properties in Sr substituted BaAl2O4:Eu2+, Dy3+ compared to parent BaAl2O4:Eu2+, Dy3+. It is probably due to the influence of 5d electron states of Eu2+ in the crystal field because of atomic size variation causing crystal defects. Dy3+ ion doping in the phosphor generates deep traps, which results in long afterglow phosphorescence.

International Nuclear Information System (INIS)

SiAlONs are ceramics with high potential as biomaterials due to their chemical stability, associated with suitable mechanical properties, such as high fracture toughness and fracture resistance. The objective of this work was to investigate the mechanical properties and the cytotoxicity of these ceramic materials. Three different compositions were prepared, using silicon nitride, aluminum nitride and a rare earth oxide mixture as starting powders, yielding Si_3N_4-SiAlON composites or pure SiAlON ceramics, after hot-pressing at 1750 deg. C, for 30 min. The sintered samples were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Furthermore, hardness and fracture toughness were determined using the Vicker's indentation method. The biological compatibility was evaluated by in vitro cytotoxicity tests. Ceramic with elevated hardness, ranging between 17 and 21 GPa, and high fracture toughness of 5 to 6 MPa m"1"/"2 were obtained. ...

British Library Electronic Table of Contents (United Kingdom)

Crystalline bis(O,O'-di-sec-butyldithiophosphato)platinum(II) was prepared and studied by means of 13C, 31P CP/MAS NMR spectroscopy and single-crystal X-ray diffraction. The unit cell of the platinum(II) compound is comprised of one centrosymmetric mononuclear molecule [Pt{S2P(O-sec-C4H9)2}2], in which the dithiophosphate groups display structural equivalence in both 31P NMR and XRD data. A pair of the dithiophosphate ligands exhibit the same S,S'-bidentate chelating structural function and form two planar four-membered chelate rings, [PtS2P], in this molecule. The planar configuration of the [PtS4] chromophore in structure 1 is governed by the dsp2-hybrid state of platinum(II). The structural states of the dithiophosphate groups in two different samples of complex 1 (one crystallised from...

International Nuclear Information System (INIS)

The adherent magnetite film thickness, corrosion rate and the loose crud on the surface of carbon steel and other structural materials were evaluated by inserting the coupons in the two autoclaves connected to the two ends of the PHT systems of Indian PHWRs. This paper includes an analysis of the results obtained during the hot conditioning of TAPP-3 and 4, Kaiga-3 and 4, and RAPP-5. The system temperatures of 230 deg C to 260 deg C and the adherent magnetic thickness of 0.30 ?m to 0.75 ?m on the internal surface of carbon steel were achieved during the hot conditioning of these reactors. The time duration of termination of the hot conditioning ranged from 48 to 71 hours. The maximum magnetite film thickness of 0.75 ?m in 71 hours and temperature 260 deg C and a minimum thickness of 0.30 nm in 48 hours at 230 deg C were achieved during hot conditionings. The XRD analyses of hot conditioned carbon steel coupons showed that oxide film constitutes only magnetite. ...

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Ultra-fine ZnAl2O4 spinel hydrogel precursor synthesized from mixed salt solutions of Zn^2^+ and Al^3^+ ions using ammonium hydroxide-hexamethylenetetramine as basic media for co-precipitation was used as bonding material and sintering aid for pure alumina system. The hydrogel powder exhibited some well-defined ZnAl2O4 spinel phases at 800^oC. Alumina compacts were fabricated by incorporating small proportions of the precursor in alumina powder and firing at different temperatures (1350-1500^oC). The degree of densification was studied by measurement of fired shrinkage, apparent porosity, bulk density and cold crushing strength. Phase compositions and microstructural features of sintered samples were evaluated by XRD and SEM respectively. Addition of 0.2% hydrogel powder to alumina exhibit...

International Nuclear Information System (INIS)

10%Pt/C catalysts were prepared by liquid reduction method. PTFE and Pt/ C catalysts were adhered to porous metal and hydrophobic Pt/C/PTFE catalysts were prepared. The structure and size of Pt crystal particles of Pt/C catalysts were analyzed by XRD, and their mean size was 3.1 nm. The dispersion state of Pt/C and PTFE was analyzed by SEM, and they had good dispersion mostly, but PTFE membrane could be observed on local parts of Pt/C/PTFE surface. Because of low hydrophobicity, Pt/C/ PTFE catalysts have low activity when the mass ratio of PTFE and Pt/C is 0.5: 1, and their catalytic activity increases markedly when the ratio is 1:1. When the ratio increases again, more Pt active sites would be covered by PTFE and interior diffusion effect would increase, which result in the decrease of catalytic activity of Pt/C/PTFE. By PTFE pretreatment of porous metal carrier, the activity of Pt/C/PTFE catalysts decreases when the mass ratio of PTFE and Pt/C is 0.5:1, and their ...

Energy Technology Data Exchange (ETDEWEB)

This work reports studies of ethanol oxidation on Pt-Sn/C catalysts with nearly the same particle size and identical overall composition having different amounts of oxide and alloyed phases. Results of characterization of physical properties by transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), and in situ dispersive X-ray absorption spectroscopy (DXAS) are presented. The variation in the amount of oxide and alloyed phases, promoted by heat treatments in mild temperature conditions, does not produce any significant particle growth. Cyclic voltammetry and oxidation of adsorbed CO in acid medium are used to probe the surface conditions. Data on the electrocatalytic activity towards ethanol oxidation, obtained by potential sweeps and chronoamperometry, are discussed and correlate well with the physical properties. This study, carried out in the absence of composition and ...

Science.gov (United States)

The nature of extralattice aluminum and its effect on acidity in zeolites was studied. A series of zeolites (some commercial), dealuminated by various methods, were obtained having Si/Al ratios between 1.5 and 20. These were characterized using volumetric sorption, XRD, AA, NMR, and reaction studies. Samples dealuminated using ammonium hexafluorosilicate were found to contain little or no extralattice aluminum. In contrast, steam-dealuminated zeolites had large amounts of extralattice aluminum. In some cases a significant portion of the extralattice aluminum was unobservable by [sup 27]Al NMR, suggesting the existence of an aluminum species of low symmetry. Proton NMR indicated that all the protons were associated with the lattice aluminum atoms. Depending on the preparation history, different groups of H-Y zeolites exhibited different maxima in catalytic activity as a function of aluminum content. The maxima in catalytic activity for n-pentane cracking was found ...

Science.gov (United States)

The magnetically fluidized bed (MFB) was used as the reactor in a novel semidry flue gas desulfurization (FGD) process to achieve high desulfurization efficiency. Experiments in a laboratory-scale apparatus were conducted to reveal the effects of approach to adiabatic saturation temperature, Ca/S molar ratio and applied magnetic field intensity on SO(2) removal. Results showed that SO(2) removal efficiency can be obviously enhanced by decreasing approach to adiabatic saturation temperature, increasing Ca/S molar ratio, or increasing applied magnetic field intensity. At a magnetic field intensity of 300Oe and a Ca/S molar ratio of 1.0, the desulfurization efficiency (excluding desulfurization efficiency in the fabric filter) was over 80%, while spent sorbent appeared in the form of dry powder. With the SEM, XRD and EDX research, it can be found that the increase of DC magnetic field intensity can make the surface morphology on the surface of the ferromagnetic ...

British Library Electronic Table of Contents (United Kingdom)

We propose and demonstrate a facile room-temperature synthetic method for obtaining water-soluble magnetic Fe3O4 nanoparticles (NPs) by combining the in situ synthesis and decomposition of a magnetic polymer hydrogel. The Fe3O4 NPs with average diameters of 6.3-8.3nm were synthesized in a cross-linked polyacrylamide (PAAm) hydrogel by coprecipitating iron ions. The decomposition of the magnetic polymer hydrogel by an aqueous solution of sodium hydroxide led to the transfer of Fe3O4 NPs into the aqueous medium. The NPs can be dispersed stably in water for more than three months. The Fe3O4 NPs were characterized by X-ray photoelectron spectra (XPS), X-ray powder diffraction (XRD), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FT-IR). The saturation magn...

Energy Technology Data Exchange (ETDEWEB)

Full text of publication follows: Large-scale problems such as nuclear waste disposal are increasingly recognized to be interconnected to small scale-mechanisms. Thus, synchrotron-based high-resolution analytical X-ray probes become important tools for exploring the micro-scale chemical reactivity of heterogeneous barrier materials used in nuclear waste repositories. In this study the layout of the micro-XAS beamline at the Swiss Light Source (SLS) will be presented. The beamline is optimized towards micro beam experiments ({approx}1 x 1 {mu}m{sup 2}) in the hard-X-ray regime (4 - {approx}22 keV) and allows to combine micro X-ray fluorescence (micro-XRF), micro X-ray absorption spectroscopy (micro- XAS), and micro X-ray diffraction (micro-XRD) investigations with radioactive samples. Furthermore, the potential of micro-XRF/XAS/XRD for acquiring spatially resolved molecular level information on the speciation and structural coordination ...

Energy Technology Data Exchange (ETDEWEB)

Here we examine Fe speciation within Fe-encrusted biofilms formed during 2-month seafloor incubations of sulfide mineral assemblages at the Main Endeavor Segment of the Juan de Fuca Ridge. The biofilms were distributed heterogeneously across the surface of the incubated sulfide and composed primarily of particles with a twisted stalk morphology resembling those produced by some aerobic Fe-oxidizing microorganisms. Our objectives were to determine the form of biofilm-associated Fe, and identify the sulfide minerals associated with microbial growth. We used micro-focused synchrotron-radiation X-ray fluorescence mapping (mu XRF), X-ray absorption spectroscopy (mu EXAFS), and X-ray diffraction (mu XRD) in conjunction with focused ion beam (FIB) sectioning, and highresolution transmission electron microscopy (HRTEM). The chemical and mineralogical composition of an Fe-encrusted biofilm was queried at different spatial scales, and the spatial relationship between primary ...

International Nuclear Information System (INIS)

Full text: Founded in 1964, Ankara Nuclear Research and Training Center (ANRTC) conducts and facilitates the scientific activities including training (summer practice, MSc and Ph D studies in physics and chemistry, IAEA fellowship programs etc.), research and other studies in nuclear and related fields. As it's a part of main duties, ANRTC has analysis on the variety of samples, and radiation protection services commercially, for radiation workers in state, public and private sectors. Research, development and application projects implemented in this Center have mostly been supported by State Planning Organization (SPO) and Turkish Atomic Energy Authority (TAEA). In addition to the projects there are on going collaborative studies with some national Universities and International Atomic Energy Agency. The main activities carried out in ANRTC can be summarized as: studies on experimental nuclear physics, application of nuclear techniques such as XRF, XRD, Gamma, ...

Science.gov (United States)

Silver iron oxide nanoparticles of fairly small size (average diameter approximately 1 nm) with narrow size distribution have been synthesized by the interaction of colloidal beta- Fe2O3 and silver nanoparticles. The surface morphology and size of these particles have been analyzed by using atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Their structural analysis has been carried out by employing x-ray diffraction (XRD), selected-area electron diffraction (SAED), optical and infrared (IR) spectroscopic techniques. The ageing of these particles exhibits the formation of self-assembly, possibly involving weak supramolecular interactions between Ag(I)O4 and Fe(III)O4 species. These particles display the onset of absorption in the near-infrared region and have higher absorption coefficient in the visible range compared to that of its precursors. Magnetic measurements reveal an interesting ...

Energy Technology Data Exchange (ETDEWEB)

Porous nanostructured LiFePO{sub 4} powder with a narrow particle size distribution (100-300nm) for high rate lithium-ion battery cathode application was obtained using an ethanol based sol-gel route employing lauric acid as a surfactant. The synthesized LiFePO{sub 4} powders comprised of agglomerates of crystallites <65nm in diameter exhibiting a specific surface area ranging from 8m{sup 2}g{sup -1} to 36m{sup 2}g{sup -1} depending on the absence or presence of the surfactant. The LiFePO{sub 4} obtained using lauric acid resulted in a specific capacity of 123mAhg{sup -1} and 157mAhg{sup -1} at discharge rates of 10C and 1C with less than 0.08% fade per cycle, respectively. Structural and microstructural characterization were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray (EDX) analysis while electronic conductivity and specific surface area ...

International Nuclear Information System (INIS)

In this paper, we report on a comparative study of active screen plasma nitriding (ASPN) and conventional dc plasma nitriding (CPN) behavior of 30CrNiMo8 low-alloy steel that has been examined under various process conditions. The process variables included active screen setup parameters (screen and iron plate top lids placed on the screen setup with 8 mm of hole size), treatment temperature (550 and 580 deg. C), gas mixture (75/25 and 25/75 of N_2/H_2) and treatment time (5 and 10 h) in 500 Pa pressure. The structure and phases composition of the diffusion zone and compound layer were studied by X-ray diffraction (XRD), microhardness tests, light optical microscopy and scanning electron microscopy (SEM). It was observed that treated sample surfaces in both CPN and ASPN methods consist of #gamma#' and #epsilon# phases, and while the nitriding time and/or temperature increases, the intensity of #epsilon# phase in the compound layer will increase for ASPN and ...

International Nuclear Information System (INIS)

Exploration for epithermal Au has been active lately in the Aegean Sea of the eastern Mediterranean Basin, both in the islands of the Quaternary arc and in those of the back-arc region. The purpose of this study was the structural mapping and analysis for a preliminary investigation of possible epithermal gold mineralization, using remotely sensed data and techniques, structural and field data, and geochemical information, for a specific area on the Island of Lesvos. Therefore, Landsat-TM and SPOT-Pan satellite images and the Digital Elevation Model (DEM) of the study area were processed digitally using spatial filtering techniques for the enhancement and recognition of the geologically significant lineaments, as well as algebraic operations with band ratios and Principal Component Analysis (PCA), for the identification of alteration zones. Statistical rose diagrams and a SCHMIDT projection Stereo Net were generated from the lineament maps and the collected field data (dip and strike ...

Energy Technology Data Exchange (ETDEWEB)

The Cu/CeO{sub 2} and Cu/Cr/CeO{sub 2} catalysts synthesized using the impregnation method were employed to investigate the selective reduction of NO{sub x} with C{sub 3}H{sub 6} at 673.15K and 1atm. The activity of CeO{sub 2} was greatly induced by loading 4wt.% of Cu onto the bare support. The presence of C{sub 3}H{sub 6} was a crucial factor for elevating the NO{sub x} conversion under lean conditions. The modification of the optimal Cu(4)/CeO{sub 2} catalyst with 3wt.% of Cr steadily improved the performance of the catalysts. Both the optimal Cu(4)/CeO{sub 2} and Cu(4)/Cr(3)/CeO{sub 2} catalysts were characterized using XRD, SEM and TPR-H{sub 2}. The co-existence of CuO, Cr{sub 2}O{sub 3} and CuCr{sub 2}O{sub 4} was believed to grant the promising performance of the Cu(4)/Cr(3)/CeO{sub 2} catalyst in SCR-HC under net oxidizing conditions.

International Nuclear Information System (INIS)

Ti and its alloys (Ti-6Al-4V) have been used in different engineering applications due to their several outstanding properties. Nevertheless, their use in practical applications is limited in many cases due to their poor tribological property. Researches are ongoing on surface modification of Ti based materials by different plasma and ion based techniques to overcome this problem. However, the conventional plasma nitriding techniques have several problems such as formation of an arc, increased possibility of surface contamination due to a comparatively higher operating pressure, production of a very thin nitrided layer after a long processing time, etc. In this present work, the possibility of a new low-pressure plasma nitriding process using a Plasma Enhanced Chemical Vapor Deposition (PECVD) based saddle field fast atom beam source on a Ti-6Al-4V alloy sample is investigated. Plasma nitriding was carried out at 900 deg. C and at a pressure 0.1 Pa for 8 h by using a beam current 0.5 ...

Energy Technology Data Exchange (ETDEWEB)

A number of high voltage cathode materials are now being considered for their ability to increase the energy density of lithium-ion batteries. In this study, a lithium-nickel composite alloy (LiNiVO{sub 4}) was synthesized using a rheological phase reduction method that incorporated mixtures of LiOH-H{sub 2}O, Ni(CH{sub 3}COO){sub 2}, 4H{sub 2}O, NH{sub 4}VO{sub 3} and C{sub 2}H{sub 2}O{sub 4}-2H{sub 2}O. The rheological phase method was used to prepare the compounds from a solid-liquid rheological mixture. Solid reactants were first mixed in a proper molar ratio, and water or solvents were added to the solid-liquid rheological body. X-ray powder diffraction (XRD) and Fourier Transform (FT) analyses were conducted to characterize the powders. Scanning electron microscopy (SEM) was used to characterize the morphological features and particle sizes of the powders. Results of the analyses indicated that the single-phase LiNiVO{sub 4} composite is capable of being ...

International Nuclear Information System (INIS)

Exploratory experiments of laser welding cast Ni-based superalloy K418 turbo disk and alloy steel 42CrMo shaft were conducted. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness and tensile strength testing. The corresponding mechanisms were discussed in detail. Results showed that the laser-welded seam had non-equilibrium solidified microstructures consisting of FeCr_0_._2_9Ni_0_._1_6C_0_._0_6 austenite solid solution dendrites as the dominant and some fine and dispersed Ni_3Al #gamma#' phase and Laves particles as well as little amount of MC short stick or particle-like carbides distributed in the interdendritic regions. The average microhardness of the welded seam was relatively uniform and lower than that of the base metal due to partial dissolution and ...

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The X-ray diffraction (XRD) and environmental scanning electron microscopy (ESEM) analyses of plasters collected from the courtyard walls of Djehuty's tomb show anhydrite, calcite, dolomite, quartz, alkali feldspars and accessorial amounts of halite and illite. The external outer bed is mainly composed by anhydrite, since the original hydrous phases of gypsum plaster were desiccated during thirty centuries in the dry land environment of the Luxor area, under low relative humidity and high temperatures. The luminescence analyses by thermoluminescence (TL) and cathodoluminescence (CL) demonstrate as one plaster sample (m8), i.e., 95% anhydrite, displays a gigantic TL emission of 33 555 a.u. and a SEM/CL emission of 2319 a.u. maxima peak. The spectra CL also exhibits a 484 nm peak attributable to the classic {sup 4}F{sub 9/2}{yields}{sup 6}H{sub 15/2} transition circa 490 nm of Dy{sup 3+} and a 573 nm emission of Dy{sup 3+} masked in a broad emission band ...

Energy Technology Data Exchange (ETDEWEB)

Several Mg-Y binary ribbons with Y content up to {approx}17.9 at.% were fabricated by melt-spinning. X-ray diffraction (XRD) revealed that the phase structure changes with increasing Y content from extended solid solution to partially amorphous, and then fully intermetallic Mg{sub 24}Y{sub 5}. Anodic potentiodynamic polarization performed in 0.01 M NaCl electrolyte (pH=12) revealed improved anodic passivity behavior compared to pure Mg for all the Mg-Y alloys. X-ray photoelectron spectroscopy (XPS) revealed that the improved passivity of Mg-Y was more related to the elemental oxidation state rather than the concentration of the surface components. To study the effect of Cl{sup -} ion on the passivity behavior, anodic potentiodynamic and potentiostatic polarization were performed on Mg-17.9 at.% Y in alkaline (pH=12) NaCl electrolytes containing Cl{sup -} ion in the concentration range from 0.00 to 0.50 M. The passive films formed in 0.01 M NaCl electrolyte were ...

International Nuclear Information System (INIS)

The paper generalizes some results of the United States/Moldova program on advanced composite organic and semiconductor light emitters. High density exciton system bound to N impurity superlattice grown by modern technologies and GaP:N, GaP:N:Sm nanocrystals distributed in transparent fluorine-containing polymers will be used as the base elements for new generation of optoelectronic devices. The work seeks to expand further the applications of GaP itself through the formation of nanocomposites. Classic and new methods are applied for preparation of GaP:N nanoparticles with the controlled dimensions developed clear quantum confinement effect. The long-term ordered bulk GaP crystals as well as their nanoparticles have been investigated by TEM, XRD, Raman scattering, and luminescent methods. The evolution of the Raman Light Scattering and luminescence spectra is reported from pure and doped GaP single crystals grown over 40 years ago and evaluated approximately every ...

International Nuclear Information System (INIS)

Fe-doped MnO2 with a hollow sea urchin-like ball chain shape was first synthesized under a high magnetic field of 10 T. The formation mechanism was investigated and discussed in detail. The synthesized samples were characterized by XRD, SEM, TEM, EMPA, and vector network analysis. By doping MnO2 with Fe, the relative complex permittivity of MnO2 and its corresponding loss tangent clearly decreases, but its relative complex permeability and its corresponding loss tangent markedly increases. Moreover, the theoretically calculated values of reflection loss show that with increasing the Fe content, the as-prepared Fe-doped MnO2 exhibits good microwave absorption capability. -- Graphical Abstract: Fe-doped MnO2 with a hollow sea urchin-like ball chain shape was first synthesized in a high magnetic field of 10 T via a simple chemical process. Display Omitted Highlights: ? Fe-doped MnO2 with a hollow sea urchin-like ball chain shape was first synthesized. ? We ...

International Nuclear Information System (INIS)

Microstructure and electrical properties of iron oxide Fe_2O_3 thin films prepared by spray pyrolysis method have been experimentally characterized. The effect of substrate temperature as well as deposition time on the structural features (crystallite size and microstrain) and electric resistivity of these films has been investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) characterized the structure study. The results of X-ray diffraction showed that with increasing substrate temperature bias the film structure changed from amorphous to crystalline at the same deposition time. At a substrate temperature of 350 deg. C and low deposition time, #alpha#-Fe_2O_3 appears almost in amorphous form. With rising the substrate temperature and deposition time, the crystallinity was improved. At T_s_u_b>350 deg. C, a well-crystallized rhombohedral phase of #alpha#-Fe_2O_3 was obtained. Single order Voigt profile method has been used to determine the ...

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Lithium ion conducting glass ceramics composed of the crystalline conductive phase Li{sub 1.4}Al{sub 0.4}(Ge{sub 1-x}Ti{sub x}){sub 1.6}(PO{sub 4}){sub 3}(x=0-1.0) with the Nasicon-type structure have been synthesized and characterized by DTA, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and complex impedance techniques. The experimental results indicated that the glass ceramics were mainly composed of solid solution Li(Ge{sub 1-x}Ti{sub x}){sub 2}(PO{sub 4}){sub 3} formed by LiGe{sub 2}(PO{sub 4}){sub 3} and LiTi{sub 2}(PO{sub 4}){sub 3} in the whole x range and showed conductivity over 10{sup -4} S/cm at room temperature. The maximum room temperature lithium ion conductivity of 6.21x10{sup -4} S/cm with an activation energy as low as 0.32 eV was obtained for the Li{sub 1.4}Al{sub 0.4}(Ge{sub 0.67}Ti{sub 0.33}){sub 1.6}(PO{sub 4}){sub 3} treated at 950 C for 18 h. Mechanisms for the enhancement of {sigma}{sub totle} in glass ...

International Nuclear Information System (INIS)

In order to investigate the role of amorphous SiO2 particles in corrosion and wear resistance of Ni-based metal matrix composite alloying layer, the amorphous nano-SiO2 particles reinforced Ni-based composite alloying layer has been prepared by double glow plasma alloying on AISI 316L stainless steel surface, where Ni/amorphous nano-SiO2 was firstly predeposited by brush plating. The composition and microstructure of the nano-SiO2 particles reinforced Ni-based composite alloying layer were analyzed by using SEM, TEM and XRD. The results indicated that the composite alloying layer consisted of ?-phase and amorphous nano-SiO2 particles, and under alloying temperature (1000 deg. C) condition, the nano-SiO2 particles were uniformly distributed in the alloying layer and still kept the amorphous structure. The corrosion resistance of composite alloying layer was investigated by an electrochemical method in 3.5%NaCl solution. Compared with single alloying layer, the ...

International Nuclear Information System (INIS)

Intermetallic compounds based on the Al-Co system were synthesized by solid state method - mechanical alloying and their properties were investigated using XRD, SEM, and DSC. The powder was used to make new targets of irradiation for gamma sources in order to enhance the specific activity and to reduce the consumption of material. The intermetallic compound AlCo was formed in the first 4 hours of milling. After 8 hours of milling the medium size of crystallites were of 5.58 nm. This value decreases with the increase of milling time up to 3 nm, corresponding to the 28 hours of grinding. There was calculated and plotted the Gibbs function, #DELTA#_f"0, for the reaction of formation AlCo and Al_3Co from the Al-Co system. It had negative values over the entire range of temperatures for both investigated compounds. After 28 hours milling a phase composition was obtained as follows: 0.2% Al; 21%Co ; 55.5%AlCo; 23.3% Al_1_3Co_4. AlCo 98% has been obtained after a ...

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A series of spinel Li{sub 4}Ti{sub 5}O{sub 12} samples were synthesized via a composite molten-salt method (CMSM) using the mixtures of LiCl and KCl with different L values (L is defined as the molar ratio of LiCl:KCl) as the reaction media. It is found that the melting point of the composite molten salt can effectively influence the formation of particles, and leads to different electrochemical performances of the as-prepare Li{sub 4}Ti{sub 5}O{sub 12}. The investigations of X-ray diffraction (XRD), particle size distribution (PSD), Brunauer-Emmet-Teller (BET) surface area, and scanning electron microscopy (SEM) indicate that the as-prepared Li{sub 4}Ti{sub 5}O{sub 12} with L = 1.5 is a pure phase, and has uniform homogeneous octahedral shape particles, rather narrow PSD, and high BET surface area. Electrochemical tests show that the optimized Li{sub 4}Ti{sub 5}O{sub 12} with L = 1.5 has an initial discharge capacity of 169 mAh g{sup -1} and an initial ...

International Nuclear Information System (INIS)

We have investigated the growth behaviors of high temperature compatible ZrO_2 insulation coatings on Ag and AgMg sheathed Bi_2Sr_2Ca_1Cu_2O_x superconducting tapes depending on number of dipping and thermal conditions. The coatings were fabricated on long-length superconducting tape substrates using a solution derived from Zr tetrabutoxide, solvent and chelating agent for high magnetic field magnets. The layer-on-layer growth behaviors were characterized by environmental scanning electron microscope (ESEM), energy dispersive spectroscopy (EDS), X-ray maps and X-ray diffraction (XRD). This research showed that the ZrO_2 coatings were regularly grown on Ag-based tape substrates and coating thickness increased with increasing number of dipping. It was found that ceramic oxides formed at temperature range 450 and 550 deg. C. The final coating thickness changed between 6 and 8 #mu#m after annealing process. Resistance of insulation measured from surface and edge ...

International Nuclear Information System (INIS)

Graphical abstract: Ordered mesoporous organic-inorganic composite film has been achieved by sol-gel and spin-coating techniques. We believe that the mesoporous composite films have a potential application as a protect coating of bipolar plate material. Display Omitted Research highlights: ? Ordered mesoporous composite film was deposited on the 304 stainless steel. ? This composite film exhibited excellent protective performance in 0.5 M H_2SO_4. ? The film exhibited a high surface tension with water contact angle close to 90"o. - Abstract: The organic-inorganic composite film was deposited on the 304 stainless steel as bipolar plate material for proton exchange membrane fuel cells by spin-coating method. As shown by XRD, N_2 adsorption-desorption and TEM, the composite films exhibit ordered mesoporous structures. The corrosion tests in 0.5 M H_2SO_4 system displayed that, compared with 304SS, the composite films made corrosion potential shifted to positive ...

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Experiments of autogenous laser full penetration welding between dissimilar cast Ni-based superalloy K418 and alloy steel 42CrMo flat plates with 3.5 mm thickness were conducted using a 3 kW continuous wave (CW) Nd:YAG laser. The influences of laser welding velocity, flow rate of side-blow shielding gas, defocusing distance were investigated. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness and tensile strength testing. Results show that high quality full penetration laser-welded joint can be obtained by optimizing the welding velocity, flow rate of shielding gas and defocusing distance. The laser-welded seam have non-equilibrium solidified microstructures consisting of {gamma}-FeCr{sub 0.29}Ni{sub 0.16}C{sub 0.06} austenite solid solution dendrites as the ...

Science.gov (United States)

Experiments of autogenous laser full penetration welding between dissimilar cast Ni-based superalloy K418 and alloy steel 42CrMo flat plates with 3.5 mm thickness were conducted using a 3 kW continuous wave (CW) Nd:YAG laser. The influences of laser welding velocity, flow rate of side-blow shielding gas, defocusing distance were investigated. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness and tensile strength testing. Results show that high quality full penetration laser-welded joint can be obtained by optimizing the welding velocity, flow rate of shielding gas and defocusing distance. The laser-welded seam have non-equilibrium solidified microstructures consisting of ?-FeCr0.29Ni0.16C0.06 austenite solid solution dendrites as the dominant and very small ...

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Chemical looping combustion (CLC) of simulated coal-derived synthesis gas was conducted with NiO oxygen carriers supported on SiO2, ZrO2, TiO2, and sepiolite. The effect of H2S on the performance of these samples for the CLC process was also evaluated. Five-cycle thermogravimetric analysis (TGA) tests at 800 C indicated that all oxygen carriers had a stable performance at 800 C, except NiO/SiO2. Full reduction/oxidation reactions of the oxygen carrier were obtained during the five-cycle test. It was found that support had a significant effect on reaction performance of NiO both in reduction and oxidation rates. The reduction reaction was significantly faster than the oxidation reaction for all oxygen carriers, while the oxidation reaction is fairly slow due to oxygen diffusion on NiO layers. The reaction profile was greatly affected by the presence of H2S, but there was no effect on the capacity due to the presence of H2S in synthesis gas. The presence of H2S decreased reduction ...

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In-situ methods are well known as powerful tools in studying catalyst formation processes, their solid state properties under working conditions and the interaction with the feed, intermediates and products to reveal reaction mechanisms. This paper gives a short overview on results of intense studies using in-situ techniques to reveal VPO catalyst generation processes, interaction of educts, intermediates and products with VPO catalyst surfaces and mechanistic insights. Catalytic data of the ammoxidation of toluene on different VPOs complete these findings. The precursor-catalyst transformation processes were preferently investigated by in-situ XRD, in-situ Raman and in-situ ESR spectroscopy. The interaction of aromatic molecules and intermediates, resp., and VPO solid surfaces was followed by in-situ ESR and in-situ FTIR spectroscopy. Mechanistic information was mainly obtained using in-situ FTIR spectroscopy and the temporal-analysis-of-products (TAP) technique. ...

International Nuclear Information System (INIS)

Research highlights: The dental implant of titanium could be modified by anodic oxidation. It was found that incorporation of strontium ions into the matrix increase the bone formation. In this study, we try to investigate the effect of corrosion property and bioactivity on coatings containing strontium by anodic oxidation. The results suggest that coatings containing strontium on titanium by anodic oxidation has the potential to show the stability and bioactivity in the clinical use. - Abstract: Pure titanium (Ti) and titanium alloys are considered as bio-inert materials in clinical use. Bioactivity is the ability to induce bone-like apatite on the material surface. The micro-arc oxidation (MAO) technique is an effective method for improving the surface properties of titanium. The aim of this study was to investigate the bioactivity and corrosion behavior of MAO coatings containing strontium, which is beneficial for biological performance. The bioactivity of materials was evaluated ...

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Red mud is a solid waste produced in the process of alumina extraction from bauxite. In this paper, recovery iron from Bayer red mud was studied with direct reduction roasting process followed by magnetic separation, and then building materials were prepared from alumosilicate residues. After analysis of chemical composition and crystalline phase, the effects of different parameters on recovery efficiency of iron were carried out. The optimum reaction parameters were proposed as the following: ratio of carbon powder: red mud at 18:100, ratio of additives: red mud at 6:100, roasting at 1300 deg. C for 110 min. With these optimum parameters, total content of iron in concentrated materials was 88.77%, metallization ratio of 97.69% and recovery ratio of 81.40%. Then brick specimens were prepared with alumosilicate residues and hydrated lime. Mean compressive strength of specimens was 24.10 MPa. It was indicated that main mineral phase transformed from nepheline (NaAlSiO{sub 4}) in ...

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This study reports on the physical-chemical behaviour of swelling di-octahedral clays (smectites) and their interaction with aqueous solutions and bacteria (Shewanella putrefaciens). Experimental results are presented for compacted clays, hydrated under confined volume conditions, using a new type of reaction-cell (the 'wet-cell' of Warr and Hoffman, 2004) that was designed for in situ X-ray diffraction (XRD) measurement. For comparison, dispersed clay systems were studied using standard batch solutions subjected to varying degrees of agitation. The combination of time-dependent in situ XRD measurements with gravimetric measurements and calculated diffraction patterns using the CALCMIX software (Plancon and Drits, 1999) allowed to successful quantification of the dynamics of water uptake and storage. This analytical procedure combined with published water vapour adsorption data enabled determination of the abundance of ...

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Magnetite nanoparticles with high self-heating capacity and low toxicity characteristics are a promising candidate for cancer hyperthermia treatment. In order to achieve minimum dosage to a patient, magnetic nanoparticles with high heating capacity are needed. In addition, the influence of physiological factors on the heat capacity of a material should be investigated in order to determine the feasibility. In this study, magnetite nanoparticles coated with lauric acid were prepared by co-precipitation of Fe{sup 3+}:Fe{sup 2+} in a ratio of 2:1, 5:3, 3:2, and 4:3, and the pH was controlled using NaOH. Structural and magnetization characterization by means of X-ray diffractometry (XRD) and a superconducting quantum interference device (SQUID) revealed that the main species was Fe{sub 3}O{sub 4} and further showed that most of the nanoparticles exhibited superparamagnetic properties. All of the magnetic nanoparticles showed a specific absorption rate (SAR) increase ...

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The partial oxidation of 1,3-butadiene has been investigated over VMoO catalysts synthesized by sol-gel techniques. Surface areas were 9-14 m{sup 2}/g, and compositions were within the solid solution regime, i.e. below 15.0 mol % MoO{sub 3}/(MoO{sub 3} + V{sub 2}O{sub 5}). Laser Raman Spectroscopy and XRD data indicated that solid solutions were formed, and pre- and post-reaction XPS data indicated that catalyst surfaces contained some V{sup +4} and were further reduced in 1,3-butadiene oxidation. A reaction pathway for 1,3-butadiene partial oxidation to maleic anhydride was shown to involve intermediates such as 3,4-epoxy-1-butene, crotonaldehyde, furan, and 2-butene-1,4-dial. The addition of water to the reaction stream substantially increased catalyst activity and improved selectivity to crotonaldehyde and furan at specific reaction temperatures. At higher water addition concentrations, furan selectivity increased from 12% to over 25%. The catalytic effects of ...

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Fuel cells based on solid oxides ('SOFC') are excellent alternative devices for power generation, when they are operated at high temperature, e.g. above 600 C. Having only fixed parts for the power generating part of the device is only one advantage of the fuel cell. Due to their unique design, these devices offer a maximum of efficiency for energy conversion compared to conventional power generating systems, which are mainly based on turbines. One aim of this thesis is the examination of alternative electrolyte and cathode materials for the SOFC applications at reduced temperatures, which means in the temperature range between 600 C and 750 C. For the first main task, several materials from the oxygen ion conducting electrolytes were selected. Different strontium and magnesium doped lanthanum gallate (LSGM) materials with additional transition metal doping were selected and prepared via two different preparation methods. The optimum calcining conditions were ...

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Sulfate attack of cement-based materials remains an important problem for the durability assessment of containers and disposal engineering barriers dedicated to the long-term storage of radioactive wastes since underground water which may reach these elements contains small quantities of sulfates (7-31 mmol/1). This work contributes to the study of sulfate-induced damage mechanisms, to their understanding and modelling. The experimental phases of this study aimed at the understanding of the different physico-chemical phenomena involved during an external sulfate attack at following their evolution and their impact on the transport and mechanical properties of the material. Leaching experiments in pure water and in a solution of sodium sulfate (with a sulfate content of 15 mmol/1), have been performed simultaneously on OPC paste (w/c 0,4)in order to allow a comparison of test results. The frequent analysis of the leachant has shown a consumption of sulfate ions by the matrix, ...

International Nuclear Information System (INIS)

Full text: Pigments possessing the ability to confer high solar reflectance have received considerable attention in recent years. The inorganic class of NIR reflective pigments are mainly metal oxides and are primarily employed in two applications: (i) visual camouflage and (ii) reducing heat build up. More than half of the solar radiation consists of near-infrared radiation (52%), the remaining being 43% visible light and 5% ultraviolet radiation. Over heating due to solar radiation negatively affects comfort in the built environment and contributes substantially to electrical consumption for air conditioning and release of green house gases. A pigment which has strong reflections in the NIR region (780-2500 nm) can be referred to as a 'cool' pigment. However, most of the NIR reflective inorganic pigments particularly yellow (eg. cadmium yellow, lead chromate, chrome titanate yellow etc.) contain toxic metals and hence their consumption is being limited. Replacing them with ...

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Energy from biomass is a CO{sub 2} neutral, sustainable form of energy. Anaerobic digestion is an established technology for converting biomass to biogas, which contains around 60% methane, besides CO{sub 2} and various contaminants. Most types of biomass contain material that cannot be digested; in woody biomass, this portion is particularly high. Therefore, conventional anaerobic digestion is not suited for the production of biogas from woody biomass. While wood is already being converted to energy by conventional thermal methods (gasification with subsequent methanation), dung, manure, and sewage sludge represent types of biomass whose energy potential remains largely untapped (present energetic use of manure in Switzerland: 0.4%). Conventional gas phase processes suffer from a low efficiency due to the high water content of the feed (enthalpy of vaporization). An alternative technology is the hydrothermal gasification: the water contained within the biomass serves as reaction ...