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Mesoporous films of platinized carbon nanotube-zirconia-Nafion composite have been used for the immobilization of tris(2,2prime-bipyridyl)ruthenium (II) (Ru(bpy)32+) on an electrode surface to yield a solid-state electrogenerated chemiluminescence (ECL) sensor. The composite films of Pt-CNT-zirconia-Nafion exhibit much larger pore diameter (3.55 nm) than that of Nafion (2.82 nm) and thus leading to much larger ECL response for tripropylamine (TPA) because of the fast diffusion of the analyte within the films. Due to the conducting and electrocatalytic features of CNTs and Pt nanoparticles, their incorporation into the zirconia-Nafion composite films resulted in the decreased electron transfer resistance within the films. The present ECL sensor based on the Pt-CNT-zirconia-Nafion gave a lin...

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A novel composite film, comprising of hydrophobic ionic liquid (IL), multi-walled carbon nanotubes (MWNTs) and gold nanoparticles (GNP), was fabricated and characterized. The GNP was introduced through electrochemical deposition on IL-MWNT gel film coated glassy carbon electrodes (GCE). Experiments showed that both IL and MWNTs could facilitate the GNP deposition. With GNP the composite film exhibited smaller electron transfer resistance and higher sensitivity in sensing guanine (G) and adenine (A). Under the optimized experimental conditions, the anodic peak currents were linear to the analyte concentration in the ranges of 0.008-2.0 {mu}M. The detection limits were down to nanomole level after an accumulation of 150 s on open-circuit. In addition, on the composite film coated GCE, the anodic peaks of G and A were well ...

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Dye-sensitized solar cells (DSSCs) based on anatase TiO2 hollow spheres (TiO2HS)/multi-walled carbon nanotubes (CNT) nanocomposite films are prepared by a directly mechanical mixing and doctor blade method. The prepared samples are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy and N2 adsorption-desorption isotherms. The photoelectric conversion performances of the DSSCs based on TiO2HS/CNT composite film electrodes are also compared with commercial-grade Degussa P25 TiO2 nanoparticles (P25)/CNT composite solar cells at the same film thickness. The results indicate that the photoelectric conversion efficiencies () of the TiO2HS/CNT composite DSSCs are dependent on CNT loading in the electrodes. A small amou...

International Nuclear Information System (INIS)

A highly sensitive and stable tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)_3 "2"+) electrogenerated chemiluminescence (ECL) sensor was developed based on carbon nanotube (CNT) dispersed in mesoporous composite films of sol-gel titania and perfluorosulfonated ionomer (Nafion). Single-wall (SWCNT) and multi-wall carbon nanotubes (MWCNT) can be easily dispersed in the titania-Nafion composite solution. The hydrophobic CNT in the titania-Nafion composite films coated on a glassy carbon electrode certainly increased the amount of Ru(bpy)_3 "2"+ immobilized in the ECL sensor by adsorption of Ru(bpy)_3 "2"+ onto CNT surface, the electrocatalytic activity towards the oxidation of hydrophobic analytes, and the electronic conductivity of the composite films. Therefore, the present ECL sensor based on the ...

Science.gov (United States)

Silicon is an attractive alloy-type anode material because of its highest known capacity (4200 mAh/g). However, lithium insertion into and extraction from silicon are accompanied by a huge volume change, up to 300%, which induces a strong strain on silicon and causes pulverization and rapid capacity fading due to the loss of the electrical contact between part of silicon and current collector. Si nanostructures such as nanowires, which are chemically and electrically bonded to the current collector, can overcome the pulverization problem, however, the heavy metal current collectors in these systems are larger in weight than Si active material. Herein we report a novel anode structure free of heavy metal current collectors by integrating a flexible, conductive carbon nanotube (CNT) network into a Si anode. The composite film is free-standing and has a structure similar to the steel bar reinforced concrete, where the ...

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Abstract Poly(butylene terephthalate) (PBT) composites containing multiwalled carbon nanotubes (MWCNTs) were prepared using a melt-blending process and used to examine the effects on the composite structure and properties of replacing PBT with acrylic acid-grafted PBT (PBT-g-AA). PBT-g-AA and multihydroxyl-functionalized MWCNTs (MWCNTs-OH) were used to improve the compatibility and dispersibility of the MWCNTs within the PBT matrix. The composites were characterized morphologically using transmission electron microscopy, and chemically using Fourier transform infrared, solid-state 13C NMR and UV-visible absorption spectroscopy. The antibacterial and electrical conductivity properties of the composites were also evaluated. MWCNTs or MWCNTs-OH enhanced the antibacterial activity and electric...

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The versatile electrospinning technique was used to successfully align and disperse multiwalled carbon nanotubes (MWCNT) in nylon 6,6 matrix to obtain composite fibers. The morphology of the composite fibers and the dispersion of the CNTs within the fibers were analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. TEM analysis revealed that the CNTs were well-dispersed, separated and aligned along the fiber axis. The thermal and mechanical properties of the composite fibers were characterized as a function of weight fraction of the CNTs. Incorporation of the CNTs in the fibers resulted in an increase in glass-transition temperature (Tg) by 7degreeC, indicating that the addition of CNTs has restricted the mobility of the polymer chains a...

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Medium-density polyethylene/multiwall carbon nanotube (MDPE/MWCNT) nanocomposites were produced by a mechanical milling method using a high-energy ball mill. The MDPE and MWCNTs were added to the ball mill at a constant 20:1 weight ratio of ball/powders and milled for 10 h to obtain polyethylene matrix nanocomposites reinforced with 0.5, 1, 2.5, and 5 weight percent of MWCNTs. To clarify the role of both MWCNT content and milling time on the morphology of MDPE, some nanocomposite samples were investigated by using a scanning electron microscope. To evaluate the role of milling on the microstructure of the nanocomposites, very thin films of MDPE/MWCNTs were prepared and studied by transmission electron microscopy. Thermal behavior of these nanocomposites was investigated by using differenti...

International Nuclear Information System (INIS)

The compressive and torsional buckling behavior of carbon nanotube bundles at room temperature is examined with classical molecular dynamics simulation. The critical compressive load and stiffness of a single carbon nanotube in the bundle are found to be similar to those of individual carbon nanotubes. However, the critical torsional moment and stiffness of a single carbon nanotube in the bundle are found to be higher than those of individual carbon nanotubes. In addition, this study demonstrates that van der Waals interactions between the nanotubes in the bundle significantly affect the critical compressive load of the nanotube bundle.

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Rheological properties of moderately concentrated solutions of cellulose in methylmorpholine N-oxide-dimethylformamide mixtures containing hydrophilic montmorillonite nanoparticles were studied. Film composite materials were prepared, and their physicomechanical properties and structural organization were studied.

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The composition of sputter-deposited HgS films was determined by electron microprobe analysis. From the relative x-ray intensity as a function of film thickness, the depth of the ionizations that produce SK sub(..cap alpha..) and HgM sub(..cap alpha..) was found to be approximately 0.65 ..mu..m at an accelerating voltage of 15 kV. This value agreed well with a value calculated from Castaings' empirical law after absorption correction. The determination of film composition was limited to sufficiently thicker films than this critical value, usually 1 - 2 ..mu..m thick. The relation between the conposition of bulk standard determined by chemical analysis and the x-ray intensity ratio was used for the correction of film composition. The results showed that the crystal structure of HgS films was ...

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A bottom-up approach is used here to combine carbon nanotubes synthesized by CVD and organically capped platinum nanoparticles electrocatalyst exhibiting a direct electrochemical activity towards oxygen reduction. Both nano-objects are handled in liquid suspension and are associated together in a controlled way. The nanocomposite liquid dispersions can be precisely controlled in terms of platinum nanoparticles to carbon nanotubes weight ratios (NP/NT) which correspond to different coverages of nanotubes by nanoparticles. Electrodes with low to ultra-low platinum loadings can then be prepared on porous fuel cell carbon supports by filtration. The direct electrochemical activity towards aqueous oxygen reduction reaction (ORR) of electrodes with platinum loadings ranging from about 1 to 60 {mu}g/cm{sup 2} is reported without any activation step in order to keep the features of the nanoparticles intact. Before that, we studied ...

International Nuclear Information System (INIS)

By means of ESCA the composition and the thickness of passive films formed on austenitic stainless steels were investigated after the attack of nitric acid at various temperatures and acid concentrations. The outermost layers of the oxide film consist of SiO_2, then a layer rich of Cr-oxid follows, containing also some Mo in the four- and sixvalent state. Ni does not contribute to the oxide film. Cr is also enriched in the metal just below the oxide film. (orig.).

International Nuclear Information System (INIS)

Nanocomposites comprising nanocrystal silicon (Si), disordered carbon (DC), and multi-walled carbon nanotubes (MWCNTs) - denoted as Si/DC/MWCNTs - have been prepared by pyrolyzing the phenol-formaldehyde resin (PFR) mixed with Si and MWCNTs. This nanocomposite anode material showed a discharge capacity of 1216 mAh/g in the first cycle, and a charge capacity of 711 mAh/g after 20 charge-discharge, much higher than that of Si/DC composite. It can be observed that Si particles wrapped in MWCNTs were homogeneously embedded into the matrix of the DC. The improved electrochemical performance is hypothesized to be mainly attributed to the morphology stability of the composite due to the excellent resiliency and distinct electric conductivity of the MWCNTs.

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The structure and composition of the passive films formed on 304 stainless steel in deaerated IN H{sub 2}SO{sub 4} were studied by RHEED, XPS and AES. The stability of the passive films as a function of passivation potential and passivation time were investigated. The role of bound water in affecting the stability of the passive films is discussed. 7 refs., 3 figs.

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, ...

Science.gov (United States)

... at compositions below -AlP 4 the films were still unstable, hydrolysing in room air, and the long term stability of higher aluminium phosphides is in ...

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A method for using in situ X-ray absorption near edge spectroscopy to determine the composition of passive, transpassive, and nonreducible thin oxide films is described. The method is demonstrated by determining the composition of the passive films formed in pH 4.5, 0.1 M acetate buffer, on 100 {angstrom} thick Fe-yCr alloys (y = 8.5, 15, 19, 23 atom %) at potentials: (1) low in the passive region ({minus}0.3 V vs. mercurous sulfate reference electrode, MSE); (2) high in the passive region; (3) in the transpassive region; and (4) in the cathodic region where the air-formed film is not fully reduced. The nonreducible film at {minus}1.2 V is entirely a Cr{sup 3+} oxide/hydroxide. This nonreducible film persists at anodic potentials. At {minus}0.3 V, the passive film on each alloy is significantly enriched in Cr. The ...

British Library Electronic Table of Contents (United Kingdom)

Mesoporous V2O5/Nafion composite films have been used for the immobilization of tris(2,2prime-bipyridyl)ruthenium (II) (Ru(bpy)$\\rm{ {_{3}^{2+}}}$) on an electrode surface to yield a solid-state electrogenerated chemiluminescence (ECL) sensor. The electrochemical and ECL behavior of Ru(bpy)$\\rm{ {_{3}^{2+}}}$ ion-exchanged into the composite films has been characterized as a function of the amount of Nafion incorporated into the V2O5/Nafion composite. The composite film with 80% Nafion content has the largest pore diameter (4.19 nm) and yields the maximum ECL response for tripropylamine (TPA) because of the fast diffusion of analyte into the film with large pores. Due to the enlarged pore size and enhanced conductivity of the V2O5/Nafion composite, the present ECL sensor based on the compo...

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Passive films were formed on a high purity Fe-23 Cr alloy in acid sulfate solutions in the presence and absence of chloride ion. The resulting film composition was investigated by Auger depth profiling. The passivated samples were exposed to a 1M NaCl solution at a constant potential slightly above the critical pitting potential, and the current-time transient was measured in order to compare the relative stability of the different films. The results obtained suggest that the formation conditions influence the chloride content of the passive film and the breakdown behavior. Passive films formed in the presence of chloride contain and are slightly less stable towards breakdown. No chloride was found in films formed in sulfate and subsequently exposed to chloride well below the pitting potential.

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Randomly oriented ZnO microsheets were successfully self-assembled on TiO2 nanoparticle (TN) film to act as the scattering layer via a cathodic electrodeposition process. The light scattering properties of ZnO microsheets were studied by UV-Vis spectrometer in the 400?800 nm wavelength range. It was found that ZnO microsheets exhibited excellent ability to scatter the incident light for ZnO microsheet-TiO2 nanoparticle (ZT) composite films. The results showed that dye-sensitized solar cells (DSSCs) fabricated with ZT composite films showed higher short-circuit density (J sc) and conversion efficiency than TN-based DSSCs, due to the light scattering properties of ZnO microsheets.

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Photocurrent and capacitance measurements of semiconductor passive films formed on metals and alloys can be used to study the electronic properties and reveal indirect information about structure and composition. The current work used these techniques to investigate the electronic properties of the passive films formed on three austenitic stainless steels, types 304L, 316L and 254SMO, in borate. Evidence was found for the existence of a large number of localised mid bandgap states, consistent with amorphous oxides. However, the flat-band potentials of the austenitic stainless steel passive films were found to be independent of both composition and measuring frequency. The most credible explanation for the bandgap values determined from photocurrent measurements is that the passive films are formed as dual layers, iron oxide outer layer and chromium oxide inner ...

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Pulsed laser deposition (PLD) is known for its capacity to reproduce a target composition on a substrate. The authors have used this deposition technique to produce thin films of transition metal chalcogenides. However, the deposits were always deficient in Te relative to the starting material (composed by a refractory metal (niobium) and a chalcogene (tellurium)). Variations of the interreticular distances have been observed with respect to fluence and substrate temperature. The authors show that spatial composition of the films is determined by a degree of crystallinity of deposit and by the reaction of formation of Te{sub 2} molecule within laser induced plume. Two kinds of deposits have been obtained: Nb{sub 5}Te{sub 4}-type thin films which have a one-dimensional structure and NbTe{sub 2}-type thin films which have a two-dimensional structure. While ...

British Library Electronic Table of Contents (United Kingdom)

Although the outer surface of single-walled carbon nanotubes (atomically thin cylinders of carbon) can be involved in a wide range of chemical reactions, it is generally thought that the interior surface of nanotubes is unreactive. In this study, we show that in the presence of catalytically active atoms of rhenium inserted into nanotubes, the nanotube sidewall can be engaged in chemical reactions from the inside. Aberration-corrected high-resolution transmission electron microscopy operated at 80?keV allows visualization of the formation of nanometre-sized hollow protrusions on the nanotube sidewall at the atomic level in real time at ambient temperature. Our direct observations and theoretical modelling demonstrate that the nanoprotrusions are formed in three stages: (i) metal-assisted d...

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The effect of Mo addition as an alloying element to stainless steel alloys is investigated by capacitance (Mott Schottky approach), and photoelectrochemistry measurements. Complementary studies were made using Auger electron spectroscopy and X-ray photoelectron spectroscopy. The Mott-Schottky approach and the photoelectrochemical studies showed that the presence of Mo as an alloying element affects the semiconductive properties of the oxide films. The analytical results have shown that the oxide films formed on stainless steels are composed by an external Fe rich region and an inner Cr rich region. No significant amount of Mo was found in the outer layers of the film. The presence of Mo leads to an increase of the chromium content in the inner layers of the film, although without increasing the film thickness. (orig.) 30 refs.

Science.gov (United States)

We presented a simple approach for in-situ synthesis of poly(dimethylsiloxane) (PDMS)-gold nanoparticles composite film based on the special characteristics of PDMS itself. It is an environmentally safe synthesis method without the requirement of additional reducing/stabilizing agents. The region where the resulting gold nanoparticles distribute (in the matrix or on the surface of the polymer) and the size of the nanoparticles, as well as the colour of the free-standing films, can be simply controlled by adjusting the ratio of curing agent and the PDMS monomer. The chemical and optical properties of these composite films were studied. Using such a method, gold nanoparticle micropatterns on PDMS surfaces can be performed. And based on the gold nanoparticles micropattern, further modification with antibodies, antigens, enzymes and other biomolecules can be achieved. To verify this ...

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Thin films of sodium montmorillonite clay and cationic polyacrylamide were grown on a polyethylene terephthalate film using layer-by-layer assembly. After 30 clay-polymer layers are deposited, with a thickness of 571 nm, the resulting transparent film has an oxygen transmission rate (OTR) below the detection limit of commercial instrumentation (< 0.005 cc/m{sup 2}/day/atm). This low OTR, which is unprecedented for a clay-filled polymer composite, is believed to be due to a brick wall nanostructure comprised of completely exfoliated clay in polymeric mortar. With an optical transparency greater than 90% and potential for microwaveability, this thin composite is a good candidate for foil replacement in food packaging and may also be useful for flexible electronics packaging.

International Nuclear Information System (INIS)

The chemical composition and the semiconducting properties of passive films formed on nickel based alloy (Alloy 600) in acidic sulphate solution, pH 2.0 at room temperature were studied using Auger analysis, voltammetric techniques and the Mott-Schottky approach. The results obtained revealed that the presence of both chromium and mixed nickel-iron oxides in the films leads to the development of a p-n heterojunction, which controls their electronic structure, similarly manner to the case of stainless steels and Alloy 600 in borate buffer solution. This behavior has been interpreted as representing of an oxide system, which has a duplex character, with an inner p-type semiconducting region, mainly formed by chromium oxide and an outer n-type semiconducting region, containing iron oxide. It could also be observed that the nickel oxide present in the films acts as a barrier layer conferring improved ...

British Library Electronic Table of Contents (United Kingdom)

Direct electrochemistry and electrocatalysis of catalase (Cat) was studied based on a nano-composite film consisting of amine functionalized graphene and gold nanoparticles (AuNPs) modified glassy carbon electrode. Graphene was synthesized chemically by Hummers and Offeman method and then was functionalized with amino groups via chemical modification of carboxyl groups introduced on the graphene surface. The nano-composite film showed an obvious promotion of the direct electron transfer between Cat and the underlying electrode, which attributed to the synergistic effect of graphene-NH2 and AuNPs. The resultant bioelectrode retained its biocatalytic activity and offered fast and sensitive H2O2 quantification. Under the optimized experimental conditions, hydrogen peroxide was detected in the...

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Titanate nanotubes were hydrothermally synthesized and their adsorption performances for lead(II) ion removal were studied. The results showed that titanate nanotubes ruptured in the adsorption process resulting in two distinct adsorption stages, thus achieving a maximum adsorption capacity of 3.752mmolg^-^1 of lead(II). Furthermore, it was found that the regeneration of titanate nanotubes loaded with the lead(II) ions can be readily achieved using the saturated EDTA disodium salt aqueous solution, thereby avoiding the trouble of disposal of adsorbent. The adsorption mechanism was also discussed in detail.

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... 1981. Retention of diphenyls, terphenyls, phenylalkanes and fluorene on graphitized thermal carbon black. Chromatographia 14:510-514. ...

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One of the major problems associated with solid waste processing technologies is the release of

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Significant ion irradiation during film growth is required for the formation of cubic boron nitride (cBN) films. Meanwhile, a huge level of intrinsic stress possibly induced by the ion bombardment has been frequently reported to result in cracking and/or lack of adhesion of deposited cBN films. The present work has been performed to investigate the interfacial and/or the buffer layer structures with better matching to the cBN film by relaxation of the film stress using ion-beam-assisted deposition (IBAD). Boron nitride films have been synthesized on Si(100) wafer and tungsten carbide (WC) substrates by depositing boron vapor under simultaneous bombardment with nitrogen ions and nitrogen-argon mixture ions in the energy range of 0.5-10 keV. Cubic BN films with enhanced tribological properties have been explored by inserting a BN layer with ...

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Passive films formed on Alloy 690 in different pH solutions at high temperatures were studied by potentiodynamic polarization, Auger electron spectroscopy, thermodynamic diagrams and the Mott-Schottky relation. The chemical compositions and electronic structures of the passive films were found to be strongly pH-dependent. In alkaline solutions, a secondary passivation was clearly observed on potentiodynamic polarization curves. The passive films were a mixture of Cr{sub 2}O{sub 3} and FeCr{sub 2}O{sub 4} below the flat band potential of nickel oxide and were NiFe{sub 2}O{sub 4} above this potential. Electronic structure models, describing the electrochemical properties of the passive films, are proposed and discussed.

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Mechanisms that govern transport, accumulation and toxicity of persistent pollutants at interfaces in aquatic ecosystems were the foci of this thesis. Specific attention was paid to humic substances, their occurrence, composition, and role in exchange processes across interfaces. It was concluded that: The composition of humic substances in aquatic surface microlayers is different from that of the subsurface water and terrestrial humic matter. Levels of dissolved organic carbon (DOC) in the aquatic surface microlayer reflect the DOC levels in the subsurface water. While the levels and enrichment of DOC in the microlayer generally show small variations, the levels and enrichment of particulate organic carbon (POC) vary to a great extent. Similarities exist between aquatic surface films, artificial semi-permeable and biological membranes regarding their structure and functioning. Acidification and liming of freshwater ...

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The chemical properties of alloys in a given environment are to a large extent governed by the surface composition. Changes of the surface composition during passivation are important features in this respect. Previous studies of single crystal Ni-Mo alloys surfaces have been reported. The aim of this work was to obtain quantitative data, for the natural oxide and the passive films formed on Ni-6% Mo(100) and (110) alloys, using Rutherford backscattering spectroscopy and nuclear reaction analysis.

British Library Electronic Table of Contents (United Kingdom)

Porous SnO2 nanotubes were prepared via electrospinning followed by calcination in air. As anode materials for lithium ion batteries, the porous nanotubes delivered a high discharge capacity of 807mAhg^-^1 after 50cycles. Even after cycled at high rates, the electrode still retained a high fraction of its theoretical capacity. Such excellent performances of porous SnO2 nanotubes could be attributed to the porous and hollow structure which facilitated liquid electrolyte diffusion into the bulk materials and buffered large volume changes during lithium ions insertion/extraction. Furthermore, the nanoparticles of nanotubes provided the shorter diffusion length for lithium ions insertion which benefited in retaining the structural stability and good rate performance. Our results demonstrated t...

International Nuclear Information System (INIS)

The neutron radiography facility was installed at the tangential beam port of the 3 MW TRIGA MARK-II research reactor. In the facility only direct film neutron radiography method is being used. The project involves development of electronic imaging system for real time neutron radiography in the existing facility with the aim of utilizing it for research and industrial applications. In establishing the electronic imaging system for real time neutron radiography the improvements of existing facility were almost done during this period. In parallel, the former facility was used for the research: (a) A study of wood and wood plastic composites with and without additive by using film neutron radiography and (b) A study of jute reinforced polymer composites by using film neutron radiography technique. (author)

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Wood-Polymer Composites (WPC) was prepared from recycled films of agricultural use and wood wastes, and LLDPE and neat PE resin mixture were also utilized in order to compare the properties. Maleic anhydride (MA) and dicumyl peroxide were used as an adhesion promoter and an initiator, respectively. Tensile properties of WPC were measured via tensile test as a function of wood filler and MA content, and fracture surface was also investigated with SEM. As the content of wood filler increased, elongation decreased but modulus increased. However, tensile strength of WPC increased only when MA was used, and 1 wt.% of MA may be high enough to increase the tensile properties. The tensile properties of WPC prepared from recycled PE films were almost same as those of neat PE resin mixture. (author). 18 refs., 5 figs.

International Nuclear Information System (INIS)

Iron oxide thin films were prepared by spray pyrolysis technique onto glass substrates from iron chloride solution. They were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and (UV-vis) spectroscopy. The films deposited at T _s #<=# 450 deg. C were amorphous; while those produced at T _s_u_b = 500 deg. C were polycrystalline #alpha#-Fe_2O_3 with a preferential orientation along the (1 0 4) direction. By observing scanning electron microscopy (SEM), it was seen that iron oxide films were relatively homogeneous uniform and had a good adherence to the glass substrates. The grain size was found (by RX) between 19 and 25 nm. The composition of these films was examined by X-ray photoelectron spectroscopy and electron probe microanalysis (EPMA). These films exhibited also a transmittance value ...

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The plastic displacements around Knoop indentations made in hard titanium/aluminum multilayered films on soft aluminum alloy substrates have been studied. Indentations were cross-sectioned and imaged using the focused-ion-beam (FIB) milling and high-resolution scanning electron microscopy (SEM), respectively. The FIB milling method has the advantage of removing material in a localized region without producing mechanical damage to the specimen. The micrographs of the cross-sectioned indentations indicate that most of the plastic deformation around the indentation is dominated by the soft aluminum substrate. There is a very small change in the multilayered film thickness around the indentation{emdash}less than 10{percent}. The plastic deformation of the thin film resembles a membrane being deflected by a localized pressure gradient across the membrane. Stress-induced voids are also observed in the multilayered ...

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The formation and breakdown of the passive films on stainless steels are mainly controlled by ionic and electronic transport processes. Both these processes are in part controlled by the electronic properties of the oxide film. Consequently, it is vital to gain a detailed perception of the electronic properties of the passive films together with structural and compositional information for a comprehensive understanding of mechanisms behind passivity and localised corrosion. As a step towards this goal the passive films formed on two main austenitic stainless steels AISI 316L and AISI 304L in borate solution were characterised by in situ Raman spectroscopy and photocurrent spectroscopy coupled with electrochemical measurements. This revealed the formation of an Fe-Cr spinel as the dominant constituent in the passive films with more Cr enrichment in the oxide ...

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The electrochemical behaviour of passive films formed on one austenitic stainless steel (AISI 304) and one ferritic stainless steel (AISI 446) in solutions with pH between 0.6 and 8.4 was studied by capacitance measurements and photocurrent spectroscopy. Compositional characterization of the passive films was done by X-ray photoelectron spectroscopy. The capacitance increases with decreasing pH. Doping densities evaluated from Mott-Schottky plots are in the range 2-6 x 10{sup 20} cm{sup -3} and increased with the pH in the neutral/alkaline range while in pH 0.6, values above 10{sup 21} cm{sup -3} were found. The bandgap energy indicates two transitions, at 2.5-2.8 and 3.2 eV. The analytical data reveal that, as the pH increased, the films become enriched in Fe(II) and Fe(III), whereas the Cr(III) gradually decreases. The films formed at very low pH had a behaviour that contrasts ...

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The growth of stoichiometric and non-stoichiometric silicon nitride films was studied experimentally on 100 mm silicon wafers by batch depositions from the dichlorosilane (SiH{sub 2}Cl{sub 2})-ammonia (NH{sub 3}) system in a hot-wall horizontal low pressure chemical vapor deposition (LPCVD) reactor. The growth kinetics were discussed in terms of the Langmuir adsorption isotherm. The kinetic parameters were determined by comparing the experimental data with a one-dimensional simulation model. The decomposition of NH{sub 3} at high temperatures was included in the simulation procedure. When the SiH{sub 2}Cl{sub 2}:NH{sub 3} ratios were greater than 1.5, a quantity higher than the thermodynamic critical values above which Si-rich nitride films begin to deposit, various SiN{sub x} films with x < 4/3 were obtained. The composition of the SiN{sub x} films was found to vary along the ...

Science.gov (United States)

In the present work, a new kind of myoglobin (Mb)/Au nanoparticles composite film was fabricated on pyrolytic graphite (PG) electrodes. Oppositely charged chitosan (CS) and silica (SiO(2)) nanoparticles were alternately adsorbed on the PG surface by the electrostatic interaction between them, forming {CS/SiO(2)}(5) layer-by-layer films. Mb and HAuCl(4) in solution were then simultaneously loaded into {CS/SiO(2)}(5) films. The loaded Au(III) in the films were electrochemically reduced into Au nanoparticles, forming nanocomposite films, designated as {CS/SiO(2)}(5)-Mb-Au. Various techniques such as cyclic voltammetry (CV), square wave voltammetry (SWV), quartz crystal microbalance (QCM), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis were used to characterize the ...

International Nuclear Information System (INIS)

Presented are the results of the investigation of the kinetics and micromechanism of the failure in impact bending of oriented-crystallized specimens having the eutectic composition Ni_3Al-Ni_3Nb and of the bimetal composed of 45 steel + M3 copper. The failure kinetics was studied by high-speed filming, whereas the fractures were studied by electron fractography. The particularities of the failure of the laminar-type composite materials were found. Analyzed was the effect of the kinetic factors and the mechanism of failure upon its energy consumption.

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Research highlights: {yields} The polarization curve of 316L SS possesses five turning potentials in passive region. {yields} Films formed at turning potentials perform different electrochemical and semiconductor properties. {yields} Dissolutions and regenerations of passive film at turning potentials are obtained by AAS and XPS. {yields} Turning potentials appearing in passive region are ascribed to the changes of the compositions of the passive films. - Abstract: The passivity of 316L stainless steel in borate buffer solution has been investigated by Mott-Schottky, atomic absorption spectrometry (AAS) and X-ray photoelectron spectroscopy (XPS). The results indicate that the polarization curve in the passive region possesses several turning potentials (0 V{sub SCE}, 0.2 V{sub SCE}, 0.4 V{sub SCE}, 0.6 V{sub SCE} and 0.85 V{sub SCE}). The passive films formed at turning potentials ...

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A composite film consisting of the mixed-addenda Keggin-type polyoxometalate alpha-K{sub 3}PMo{sub 3}W{sub 9}O{sub 40} (PMo{sub 3}W{sub 9}) and silver nanoparticles (AgNPs) was fabricated on quartz, silicon, and ITO by the layer-by-layer self-assembly method. The regular growth of the multilayer film was monitored by UV-vis spectroscopy, and the morphology was measured by atomic force microscopy (AFM). The multilayer film embedded by AgNPs exhibited the photo-luminescence ascribed to electronic transitions from excited states to d levels of the silver nanoparticles. The composite film also showed electrocatalytic activity towards reduction of NO{sub 2}{sup -}, H{sub 2}O{sub 2}, ClO{sub 3}{sup -}, BrO{sub 3}{sup -}, and IO{sub 3}{sup -} attributed to tungsten-centered and molybdenum-centered redox processes of PMo{sub 3}W{sub 9}.

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Experiments have been carried out in water at 355 C to study transport of oxygen and hydrogen (as deuterium) in growing corrosion films. Composition of the films was also examined in 2.9 Mev and 3.9 Mev /alpha/-particle backscattering experiments. Corrosion occurs predominantly by oxygen diffusion through the film via grain boundary or similar short circuit diffusion paths, to form fresh oxide at the oxide metal interface. Increasing grain size within thick pre-breakaway films contributes to a decrease in diffusivity. The rate transition results from the generation of new diffusion pathways in previously protective oxide. Unexpectedly high concentrations of deuterium were observed. 26 refs.

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Titanium oxides were grown anodically to selected final potentials on grade II polycrystalline titanium under different anodization rates. XPS and RBS results show that the oxide consists of primarily TiO2 with a non-stoichiometric oxide/metal interface, with the slower growth rate associated with a thicker layer at the interface. Characterization using TEM reveals that the structure of the oxide evolves from a primarily amorphous phase to islands of crystallites in an amorphous matrix, to an entirely crystalline phase by increasing the polarization potential. Slower growth rates tend to remain crystalline at higher potentials. The mechanical strength of oxide films extracted from load-depth data by nanoindentation varies dramatically for oxide films grown by different rates at 9.4 V, and to a lesser extent at lower potentials. The variation of film strength is associated with both compositional and ...

British Library Electronic Table of Contents (United Kingdom)

In the present study the optical properties of co-evaporated indium sulfide thin films are investigated. Before being optically characterized, the composition as well as the crystalline properties of the film have been checked with the help of energy dispersive spectroscopy (EDX) and X-Ray diffraction (XRD) analyses. The optical absorption coefficient ? of this indium sulfide film has been deduced from reflectivity R(?) and transmission T(?) measurements. The fit of the curve representing ?(h?) suggests that the ?-In2S3 has an indirect bandgap of 2.01?eV. Density functional theory (DFT) calculations are performed on this indium sulfide compound, using TB-LMTO code. Through these band structure investigations, an indirect bandgap is predicted as observed experimentally. The top of the valen...

International Nuclear Information System (INIS)

The compositions of passive films formed on Fe-17Fr-13Ni (at. %) and Fe-18.5Cr-14Ni-1.5Mo (100) single crystals have been determined and the structure of the alloy under the film has been investigated. The alloys were passivated in 0.05M H_2SO_4 at 250 mV/SHE for 30 min. The oxygen content was measured by nuclear microanalysis using the "1"6O(d,p) "1"7O* reaction. The oxygen content in the passive film is similar for the two alloys and equal to (12#+-#2) 10"1"5 O/cm"2. The cationic compositions of the passive films have been determined by "4He channeling at two incident beam energies: 0.8 and 2.0 MeV. For the two alloys studied, a total cation content of (5#+-#2)10"1"5 at/cm"2 is found in the passive films. The corresponding thickness is about 12 A. There is an excess of oxygen, which can be attributed to the presence of hydroxyls and ...

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The temperature effect on corrosion behaviors of PbCaSnCe alloy in 4.5 M H{sub 2}SO{sub 4} solution was investigated by using potentiodynamic curve, electrochemical impedance spectra (EIS), Mott-Schottky plot and photocurrent response methods. It was found that PbCaSnCe alloy was in passive state in sulfuric acid solution, a passive film can be formed on alloy surface. The compositions of passive films formed at 0.9 V for 2 h under different temperatures were detected by X-ray photoelectron spectroscopy (XPS). The results showed that the film resistance and the transfer resistance decreased with the increment of the solution temperature. Mott-Schottky analysis and the photocurrent response revealed that the passive film exhibited n-type semi-conductive character, the donor density of the passive film decreased with increasing the solution temperature. ...

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Ion bombardment during deposition can significantly modify the film properties. In the partially ionized beam deposition, ions derived from the depositing material, i.e., the self-ions, are used during deposition. Cu films were deposited on SiO{sub 2} substrates at room temperature using 1% Cu self-ions with an energy ranging between 0--4 keV. We studied the microstructures of the Cu films using x-ray diffraction and transmission electron microscopy, measured the impurity level inside the films using secondary ion mass spectrometry, and performed the resistivity measurements using a four point probe. The results indicate that there is an optimum ion energy around 2 keV at which, the integrated x-ray intensity ratio {ital I}(111)/{ital I}(200) reaches its maximum value indicating a strong {l angle}111{r angle} texture, while the impurity concentration and resisitivity are minimum. The correlation between ...

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The corrosion properties of sputtered molybdenum and molybdenum silicide films in hydrochloric acid (HCl) have been studied by means of potentiodynamic measurements. Contributions from the substrate to the corrosion behaviour was avoided by depositing the films on inert aluminium oxide (Al{sub 2}O{sub 3}). The compositions studied were Mo, MoSi{sub 0.58}, MoSi{sub 1.04}, MoSi{sub 1.4} and MoSi{sub 1.9-2.1}. Characterisation of the samples was made by X-ray diffraction (XRD) and scanning electron microscopy (SEM) before and after corrosion. X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were used to analyse the polarised films. Corrosion of Mo{sub 3}Si was found in the molybdenum-rich samples (MoSi{sub 0.58}) containing the two phases Mo{sub 3}Si and Mo{sub 5}Si{sub 3}. Polarisation curves for these films showed one passivation peak at 228 mV vs. the ...

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MmMg{sub 12}-Ni amorphous or nanocrystalline composites (Mm: Ce-rich mischmetal) were prepared through the ball-milling method, and their electrochemical hydrogen storage performance was investigated and compared with that of ball-milled CeMg{sub 12}-Ni composites. It was found that the ball-milled MmMg{sub 12}-Ni composites had larger initial discharge capacities and better high rate dischargeability. Analysis of electrochemical impedance spectra (EIS) shows that the reaction resistance and hydrogen diffusion resistance of the ball-milled MmMg{sub 12}-Ni composites are lower as a result of the decrease in Ce content, and thus can contribute to the larger discharge capacity and better high rate dischargeability. Additionally, the cycle performance of the ball-milled MmMg{sub 12}-Ni composites is better than those of the ball-milled CeMg{sub 12}-Ni composites. ...

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The ball-milling method was used to produce Mg-50 wt.% ZrFe{sub 1.4}Cr{sub 0.6} composite. The thermodynamic, kinetic, and cycling properties, as well as the resistance to oxidation were examined. This composite possesses excellent kinetic properties, even at moderate temperature. Scanning electron microscopy, energy-dispersive spectrum, transmission electron microscopy and X-ray diffraction were used to characterize the composite before and after hydriding. The fine ZrFe{sub 1.4}Cr{sub 0.6} particles covering Mg particles acting as a ''catalytic film'', a significant amount of imperfections and some alloy powder in the Mg matrix introduced by ball milling all contributed to the enhanced absorption/desorption rate. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Modelization of crack propagation and theoretical prediction of rupture are the two main objectives of researchers in stress corrosion cracking. Nevertheless, to reach this aim, the behavior of the passive film which appears spontaneously on the substrate in contact with an environment has to be known. This structural and mechanical characterization is all the more difficult because the number of parameters is important: crystallinity rate, defects concentration, thickness (about a few nanometers), electric field, chemical composition (a lot of oxides are present), peeling layers (atomic structure for example) and some hypothesis can be made about their multi-layer structure, their chemical composition or their epitaxial character... Passive films formed on 316L or 304L stainless steels in different aqueous solutions (in ambient air, in MgCl{sub 2} at 117 deg. C...) have been studied and some important ...

International Nuclear Information System (INIS)

Direct electrochemistry and electrocatalysis of catalase (Cat) was studied based on a nano-composite film consisting of amine functionalized graphene and gold nanoparticles (AuNPs) modified glassy carbon electrode. Graphene was synthesized chemically by Hummers and Offeman method and then was functionalized with amino groups via chemical modification of carboxyl groups introduced on the graphene surface. The nano-composite film showed an obvious promotion of the direct electron transfer between Cat and the underlying electrode, which attributed to the synergistic effect of graphene-NH2 and AuNPs. The resultant bioelectrode retained its biocatalytic activity and offered fast and sensitive H2O2 quantification. Under the optimized experimental conditions, hydrogen peroxide was detected in the concentration range from 0.3 to 600 ?M with a detection limit of 50 nM at S/N = 3. The biosensor exhibited some ...

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Development of useful high-critical-temperature (high-{Tc}) superconductors requires synthesis of superconducting compounds; fabrication of wires, tapes, and films from these compounds; production of composite structures that incorporate stabilizers or insulators; and design and testing of efficient components. This report describes technical progress of research and development efforts aimed at producing superconducting components based on the Y-Ba-Cu, Bi-Sr-Ca-Cu, Bi-Pb-Sr-Ca-Cu, and Tl-Ba-Ca-Cu oxides systems. Topics discussed are synthesis and heat treatment of high-{Tc} superconductors, formation of monolithic and composite wires and tapes, superconductor/metal connectors, characterization of structures and superconducting and mechanical properties, and fabrication and properties of thin films. Collaborations with industry and academia are also documented. 10 figs.

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This paper describes the experimental results of long-life solid lubricated ball bearings tested under high-vacuum of 10 exp -4 Pa, high-temperature of 300 C, and high-speed (9000 rpm) conditions. For full ball-type bearings, the thin soft metals, either Ag or Pb, which were coated on the races and balls, appeared to have good torque properties. However, the durability of such bearings was less than 300 hours. The transfer films from the lamellar solid MoS2 and metal composite retainers improved the torque and wear properties. For ceramic, i.e., silicon nitride, balls used with steel rings, wear occurred on the inner rings. All ceramic bearings with composite retainers showed improved torque and wear properties. 18 refs.

British Library Electronic Table of Contents (United Kingdom)

The light-emitting properties of cubic silicon carbide films grown by vacuum vapor phase epitaxy on Si(100) and Si(111) substrates under conditions of decreased growth temperatures (T gr ? 900?700?C) have been discussed. Structural investigations have revealed a nanocrystalline structure and, simultaneously, a homogeneity of the phase composition of the grown 3C-SiC films. Photoluminescence spectra of these structures under excitation of the electronic subsystem by a helium-cadmium laser (?excit = 325 nm) are characterized by a rather intense luminescence band with the maximum shifted toward the ultraviolet (?3 eV) region of the spectral range. It has been found that the integral curve of photoluminescence at low temperatures of measurements is split into a set of Lorentzian components. Th...

International Nuclear Information System (INIS)

In this study, WO3 thin films were grown on glass substrates using an aqueous solution containing tungstate (NH4)2WO4 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 Ts = 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(?) and reflectance R(?) ...

CERN Document Server

Non-evaporable thin film getters of various compositions have been produced by sputtering. Among about 20 materials which have been studied, the lowest activation temperature (about 180 degree C) has been displayed by a Ti-Zr-V coating obtained from a cathode made of intertwisted elemental wires. In order to optimize the vacuum properties of this film various production parameters, including the substrate temperature during coating, have been varied. The films have been characterized by pumping speed measurement, secondary electron microscopy, and X-ray diffraction. It has been found that the substrate coating temperature affects significantly the activation temperature, the pumping speed and the gas surface capacity. The highest pumping speed values, obtained for substrate coating temperatures of 250 degree C and 300 degree C, are clearly correlated with the increased surface roughness and porosity of ...

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The passive films formed in stainless steels are thin and fine oxide films, a high corrosion resistance can be provided by these films. This study formed SiO2 protective coating on the substrate of SUS 304 stainless steels by chemical vapor deposition using TEOS-O3 system. Firstly, relations of substrate temperature and deposition rate of films, chemical composition, refractive index of films were investigated. Then, the corrosion resistance of SUS 304 stainless steels coated SiO2 films was examined by activation time and an anodic polarization curve in 1 kmol[center dot]m[sup -3] HCl solution. The results were obtained as follows. Thickness of SiO2 films linearly increases with time at the deposition temperature of 473 to 673 K. Si-OH bonds would disappear above the deposition temperature of 573 K, almost perfect SiO2 ...

Science.gov (United States)

The dissimilatory metal reducing bacterium Shewanella sp. strain HN-41 was first reported to produce novel photoactive As-S nanotubes via reduction of As(V) and S(2)O(3)(2-) under anaerobic conditions. Here we report the draft genome sequence and annotation of strain HN-41. PMID:21868804

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Desorption behavior of pyrene, phenanthrene and naphthalene from fullerene, single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) was examined. Available adsorption space of carbon nanotubes (CNTs) was found to be the cylindrical external surface, neither the inner cavities nor inter-wall spaces due to impurities in the CNTs and restricted spaces (0.335 nm) of the MWCNTs, respectively. Desorption hysteresis was observed for fullerene but not for CNTs. Deformation-rearrangement was proposed to explain the hysteresis of polycyclic aromatic hydrocarbons (PAHs) for fullerene, due to the formation of closed interstitial spaces in spherical fullerene aggregates. However, long, cylindrical carbon nanotubes could not form such closed interstitial spaces in their aggregates due to their length, thus showing no significant hysteresis. High adsorption capacity and reversible adsorption ...

Environmental Research Database

DescriptionThe objective is to exploit the use of wheat as an industrial raw material and understand the effect of material variation in wheat starch and flour on final material properties for food packaging applications. The project will focus on property enhancement in terms of stiffness, strength, toughness, moisture barrier resistance, transparency, ageing resistance, microbial stability and biodegradability of starch-based packaging materials made by sheet extrusion and thermoforming processes, in ord [continued...

Energy Technology Data Exchange (ETDEWEB)

Coatings and sensors having both steric and chemical selectivity. Controlled porosity provides the steric selectivity, whereas chemically tailored film properties, using controlled composition or modification by coupling agents, chemical species replacement, or chemical species within pores, provide the chemical selectivity. Single or multiple layers may be provided.

British Library Electronic Table of Contents (United Kingdom)

The carbon fibers (CF) were pre-treated in two different ways: no pre-treatment, and activation in HNO3 plus application of toluene-2,4-diisocyanate (TDI). Carbon fibers have been introduced into polyurethane (PU) composite coatings. The tribological behaviors of the polyurethane composite coating filled with CF or TDI-modified CF (TDI-CF) were studied using a ring-on-block wear tester under dry sliding, and the worn surfaces of the filled PU coatings and transfer films formed on the surface of the counterpart ring sliding against the PU coating were investigated by SEM and optical microscope (OM), respectively. Owing to the effective improvement of the interfacial adhesion between the CF and polyurethane matrix, compared with the cases of untreated CF, the employment of low content TDI-CF...

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In the present paper, the chemical composition of passive films formed on both phases of two types of duplex stainless steels (UNS S31803 and UNS S32304) is determined at the micro-scale using Auger electron spectroscopy (AES). Samples were either mechanically polished (down to diamond pastes) or electrochemically etched in acidic solutions. The micro-electrochemical behavior of samples was then determined in sodium chloride media by means of the electrochemical micro-cell technique (capillary diameters of 30 {mu}m). The results obtained were analyzed considering the passive film chemical composition. Quantitative relationships between electrochemical parameters and the distribution of chromium and iron in the oxide layer were found. Due to differences in mechanical properties between ferrite and austenite, a heterogeneous stress distribution is generated in both phases. A method based on ...

International Nuclear Information System (INIS)

Nanoporous materials have become indispensable in many fields ranging from photonics, catalysis and semiconductor processing to biosensor infrastructure. Rapid and energy efficient process fabrication of these materials is, however, nontrivial. In this communication, we describe a simple method for the rapid fabrication of these materials from colloidal dispersions of Polymethyl Silsesquioxane nanoparticles. Nanoparticle-polymer composites above the decomposition temperature of the polymer are examined and the entropic gain experienced by the nanoparticles in this rubric is harnessed to fabricate novel highly porous films composed of nanoparticles. Optically smooth, hydrophobic films with low refractive indices (as low as 1.048) and high surface areas (as high as 1325 m2 g-1) have been achieved with this approach. In this communication we address the behavior of such systems that are both temperature and substrate surface ...

International Nuclear Information System (INIS)

Modelization of crack propagation and theoretical prediction of rupture are the two main objectives of researchers in stress corrosion cracking. Nevertheless, to reach this aim, the behavior of the passive film which appears spontaneously on the substrate in contact with an environment has to be known. This structural and mechanical characterization is all the more difficult because the number of parameters is important: crystallinity rate, defects concentration, thickness (about a few nanometers), electric field, chemical composition (a lot of oxides are present), peeling layers (atomic structure for example) and some hypothesis can be made about their multi-layer structure, their chemical composition or their epitaxial character... Passive films formed on 316L or 304L stainless steels in different aqueous solutions (in ambient air, in MgCl_2 at 117 deg. C...) have been studied and some important ...

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 ...

Energy Technology Data Exchange (ETDEWEB)

Recently, the development of shape memory alloy (SMA) actuators, in the forms of wire, thin film and stent have been found increasingly in the fields of materials science and smart structures and engineering. The increase in attraction for using these materials is due to their many unique materials, mechanical, thermal and thermal-mechanical properties, which in turn, evolve their subsequent shape memory, pseudo-elasticity and super-elasticity properties. In this paper, a common type of SMA actuator, Nitinol wires, were embedded into advanced composite structures to modulate the structural dynamic responses, in terms of natural frequency and damping ratio by using its shape memory and pseudo-elastic properties. A simple theoretical model is introduced to estimate the natural frequency of the structures before and after actuating the embedded SMA wires. The damping ratios of different SMA composite beams were measured ...

Science.gov (United States)

The relationship between processing, microstructure, and properties was studied for A-15 compounds in multifilamentary composites produced by solid-state diffusion and in thin-film samples produced by vapor deposition. Grain sizes of A-15 superconducting compounds were measured by transmission electron microscopy of multifilamentary composites reacted at various temperatures. Critical current densities at 4.2 K and fields up to 6 T were found to be similar for niobium-tin, vanadium-gallium, and vanadium-silicon of the same grain size. Study of the Cu-V-Si phase diagram led to the production of improved multifilamentary vanadium-silicon conductors. The effects of various alloying elements on A-15 layers produced by solid-state diffusion were studied. The most promising new observation was that tantalum can be incorporated into niobium-tin reaction layers, leading to an enhancement of critical currents at high fields. The ...

International Nuclear Information System (INIS)

An analysis of the passive films formed on amorphous alloys of the system Fe-10% Cr-5% Mo-P-metalloid and Fe-10% Cr-5% Mo-B-Si revealed that they are more markedly enriched with chromium in silicon-free alloys. In silicon-containing amorphous alloys the passive films were highly enriched with silicon, which occurred in these films in the form of a corrosion product close to SiO_2. As shown by the investigations of a study of the anodic behavior of Fe_4_0Ni_4_0P_1_4B_6 and Fe_4_0Ni_3_8Mo_4B_1_8, phosphorus facilitates the passivation of amorphous alloys by reducing the solution current in the active state and enriching the surface layers of the metal in the form of a black prepassivation film which also contains nickel and iron. The behavior of Fe-Ni amorphous alloys containing only boron as metalloid additive differs little from that of crystalline alloys of similar composition but ...

Science.gov (United States)

This report summarizes the results obtained under a contract from 1974 to 1977, focusing on silicide formation of thin metal films on a Si substrate. The main thrust of the effort was directed at: (1) Development of the data base on thin-film silicide formation, and the investigation of the influence of the Si substrate on the silicide formation. When taken in context with results of other studies, the data obtained exhibit a clear pattern of behavior among the various metal films, but the detailed picture appears to be complex; (2) Development of marker experiments by ion-implanted Ar or Xe markers; (3) Clarification of the role played by oxygen contamination in silicide formation; (4) Stability of silicide layers; (5) Reaction of metal layers with SiO/sub 2/; (6) Electrical characteristics of Pd/sub 2/Si; and (7) A computer program was written to synthesize backscattering spectra for thin-film samples ...

Environmental Research Database

Objectives1. We will use reduction of lysosomal stability as an indicator of cell injury induced by C-60 fullerenes and carbon nanotubes in the liver analogue or digestive gland (hepatopancreas) of marine mussels. Molluscan hepatopancreatic digestive cells are key to normal function and are a sensitive key interface with the environment. Reduction of lysosomal stability is mechanistically linked with impaired health of the whole animal. 2. We will also test the hepatopancreatic digestive cells for evide [continued...]DescriptionNanotechnology is a major innovative scientific and economic growth area, which may present a variety of hazards for environmental and human health. The surface properties and very small size of nanoparticles and nanotubes provides surfaces that may bind and transport toxic chemical pollutants, as well as possibly being toxic in their own right by generating reactive oxygen species (ROS). There is a wealth of evidence ...

Energy Technology Data Exchange (ETDEWEB)

Alloy 600 is commonly used in the primary systems of PWR plants because of its excellent resistance to a stress corrosion cracking and pitting. But a stress corrosion cracking and pitting corrosion are occasionally observed under PWR conditions, which may be correlated with the passive film on the Alloy 600 surface. There is little information on the composition of films growing on the surface of Alloy 600 at high temperature. Therefore, an understanding of the basic electrochemical behaviors about an anodic dissolution and the passivation of the bare surface of metals and alloys provides important information about localized corrosions like a SCC and pitting. Oxide on the steel surfaces in an aqueous solution above 100 .deg. C is composed of a duplex film structure. The inner layer of the oxide is dense and less porous, which is formed by a growth of the oxide layer on the metal surface. Outer layer of ...

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Various methods for storing hydrogen have been examined in an effort to find ways to store hydrogen in increasingly smaller volumes with decreasing weight of the whole hydrogen storage system. Metal hydrides, in which hydrogen is chemically bound to a metal atom, are considered to be very promising candidates for hydrogen storage because they have high gravimetric and volumetric storage capacities. This study investigated the effect of different magnesium (Mg) and aluminium (Al) ratios on the absorption and desorption properties of thin films. Neutron reflectometry (NR) was used in this study to better understand the absorption and desorption properties of commercially promising hydrogen storage materials. The large negative scattering length of hydrogen atoms changes the reflectivity curve substantially, so that NR can determine the total amount of stored hydrogen as well as the hydrogen distribution along the film normal, with nanometer ...

International Nuclear Information System (INIS)

FexZn1-x alloys were electrochemically deposited on aluminum substrates from a sulfate bath. The K?/K? x-ray intensity ratios of Zn and Fe in FexZn1-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 241Am 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 FexZn1-x thin films for different values of x. The reason ...

UK PubMed Central (United Kingdom)

Tubular membrane structures are widespread in eukaryotic cells, but the mechanisms underlying their formation and stability are not well understood. Previous work has focused on tube extrusion from...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Effects of dopant and coating carbon nanotube on anodic performance of Si were studied for metallic anode Li ion rechargeable battery with large capacity. Although the large Li intercalation capacity higher than 1500mAhg{sup -1} is exhibited on pure Si, it decreased drastically with increasing cycle number. Increasing the electrical conductivity by doping Cr or B is effective for increasing the initial capacity and the cycle stability of Si for Li intercalation. Coating semiconductive Si with the carbon nanotube by decomposition of hydrocarbon is effective for increasing the cycle stability, though the initial Li intercalation capacity slightly decreased. Conducting binder is also important for increasing the cycle stability and it was found that Li intercalation capacity higher than 1500mAhg{sup -1} can be sustained by using poly vinyliden fruolide. Consequently, reversible Li intercalation capacity of 1500mAhg{sup -1} was successfully ...

British Library Electronic Table of Contents (United Kingdom)

The formation of nanoparticles during the radiation-induced chemical reduction of silver ions, copper ions, and nickel ions in films based on poly(acrylic acid)-poly(ethylenimine) complexes are studied via electron microscopy. This approach allows preparation of composites containing nanoparticles that are randomly distributed in the polymer matrix and materials with a regular spatial distribution of nanoparticles across the film thickness and in subsurface layers. The structure of metal-polymer hybrid materials is dependent on the irradiation conditions, the type of reduced metal ions, and their initial content in polymer matrices. The ratio between the rate of nucleation and the rate of growth of nanoparticles in the matrices of interpolyelectrolyte complexes depends on the intensity of ...

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This report describes experiments to determine whether a wiped film evaporator (WFE) might be used to concentrate low-level liquid radioactive waste (LLLW). Solutions used in these studies were surrogates that contain no radionuclides. The compositions of the surrogates were based on one of Oak Ridge National Laboratory`s (ORNL`s) Melton Valley Storage Tanks (MVSTs). It was found that a WFE could be used to concentrate LLLW to varying degrees by manipulating various parameters. The parameters studied were rotor speed, process fluid feed temperature and feed rate, and evaporator temperature. Product consistency varied from an unsaturated liquid to a dry powder. Volume reductions up to 68% were achieved. System decontamination factors were consistently in the range of 10{sup 4}.

International Nuclear Information System (INIS)

A carbon nanotube (CNT) tip, which assembled on the sharp end of a Si tip by dielectrophoresis, was structurally modified using focused ion beam (FIB). We described the imaging characterization of the FIB-modified CNT tip in noncontact AFM mode in terms of wear, deep trench accessibility, and imaging resolution. Compared to a conventional Si tip, the FIB-modified CNT tip was superior, especially for prolonged scanning over 10 h. We conclude that modified CNT tips have the potential to obtain high-quality images of nanoscale structures.

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The Rocky Flats Plant (RFP) generates large volumes of a low level aqueous waste stream high in nitrate salts. The aqueous waste is concentrated by evaporation and then mixed with Portland cement prior to transport and disposal. Planned process upgrades include a new horizontal thin film evaporator. Temperature of brine at discharge end of the new evaporator will be near boiling point. Introduction of hot water to cement can degrade the monolithic waste form. However, the RFP salt waste contains high concentrations of compounds known to retard hydration. This paper discusses impact of introducing high temperature waste to cement. The study evaluated three waste compositions: (1) highest probable nitrate composition, (2) highest probable chloride composition, and (3) current composition. Results showed that compressive strength of final waste form increased with brine temperature, ...

Energy Technology Data Exchange (ETDEWEB)

To obtain Pinus wood-plastic composites, wood samples were impregnated with methyl methacrylate and polymerized by the use of gamma rays from a /sup 60/Co at different dose exposure and total dose. The best percentage of polymerization was obtained with the exposure of 2.0 MR of gamma radiation. It was found that the impregnation and polymerization, determined by the density values along the samples were uniform. The density became 2.6 times higher in relation to the control samples. The storage of the impregnated wood samples showed losses of the monomer, even when wrapped with aluminum or polyethylene film. It is recommended that the wood samples should be irradiated soon after impregnation.

British Library Electronic Table of Contents (United Kingdom)

This paper aims to study fundamentally the impacts of membrane properties on the reactive dye removal from dye/salt mixtures by nanofiltration membranes. To begin with, two types of nanofiltration membranes of similar pore size, namely asymmetric cellulose acetate membrane and thin-film composite polyamide membrane were fabricated, and their key physical, chemical and performance properties were characterized. After that, these resultant membranes were employed to perform dye removal experiments with aqueous solutions of reactive black 5 and NaCl under different operational parameters. The dye removal rate and steady permeate flux were determined and correlated with the measured membrane properties. It was found that there were significant differences between the dye removal performances o...

British Library Electronic Table of Contents (United Kingdom)

This study investigates the applicability of n-type TiO2 and p-type NiO on the FTO-glass (Fluorine doped tin oxide, SnO2:F) substrate of the working electrode in a dye-sensitized solar cell (DSSC). The working electrode was designed and fabricated by depositing a film of TiO2/NiO composite particles, which were prepared by mixing the Ni powder with TiO2 particles using dry mixing method, on a FTO-glass substrate using a spin coating process. The working electrode was then immersed in the solution of N-719 (Ruthenium) dye at a temperature of 70degreeC for 6h. Moreover, a thin film of platinum (Pt) was deposited on the FTO-glass substrate of the counter electrode using an E-beam evaporator. Finally, the DSSC was assembled, and the short-circuit photocurrent, the open-circuit photovoltage and...

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A lightweight, low permeability liner for graphite epoxy composite compressed gas storage vessels. The liner is composed of polymers that may or may not be coated with a thin layer of a low permeability material, such as silver, gold, or aluminum, deposited on a thin polymeric layer or substrate which is formed into a closed bladder using torispherical or near torispherical end caps, with or without bosses therein, about which a high strength to weight material, such as graphite epoxy composite shell, is formed to withstand the storage pressure forces. The polymeric substrate may be laminated on one or both sides with additional layers of polymeric film. The liner may be formed to a desired configuration using a dissolvable mandrel or by inflation techniques and the edges of the film seamed by heat sealing. The liner may be utilized in most any type of gas storage system, and is particularly applicable ...

Energy Technology Data Exchange (ETDEWEB)

Characterization of high temperature superconducting film and bulk samples has been carried out using 2 MeV [alpha]-particle Rutherford backscattering, 2.4 MeV proton elastic scattering, 2.4 MeV proton-induced x-ray emission, 9 MeV proton induced [gamma]-ray emission and 100 MeV iodine elastic recoil detection analysis techniques. The objective was to compare different ion beam based techniques for: (i) compositional analysis; and (ii) consistency of the results obtained for samples prepared using similar preparation methodology. (author).

International Nuclear Information System (INIS)

The possible surface enrichment of chromium and molybdenum during dissolution of Fe18Cr (110) and Fe18Cr3Mo (110) alloys at constant potentials in the passive region is elucidated by taking into account quantitative information on partial dissolution rates of alloy components as measured by #gamma#-spectrometry and on chemical composition of passivating films as measured by ESCA and AES. When combining results from all methods it is found that chromium under all conditions is enriched in the passivating films. An accumulation of chromium in the alloy is also indicated. For molybdenum, an enrichment in the passive film is observed at -0.2 V (SCE), whereas in the potential interval 0.1 - 0.9 V, the molybdenum enrichment as determined by ESCA and AES is hardly significant. On the other hand, #gamma#-spectrometry gives a clear indication of molybdenum enrichment in both potential. (author).

Energy Technology Data Exchange (ETDEWEB)

The corrosion behaviour of the stainless steels 304, 316 Ti, 25Cr-20Ni-Mo-Ti, nickel base alloys Hastelloy C4, Inconel 625, Incoloy 800, Ti and Ti-0.2% Pd alloy has been studied in the aerated or deaerated solutions at 20/sup 0/C and 90/sup 0/C whose compositions are representative of interstitial ground waters: granitic or clay waters or salt brine. The electrochemical techniques used are voltametry, polarization resistance and complexe impedance measurements. Electrochemical data show the respective influence of the parameters such as temperature, solution composition and dissolved oxygen, addition of soluble species chloride, fluoride, sulfide and carbonates, on which depend the corrosion current density, the passivation and the pitting potential. The inhibition efficiency of carbonate and bicarbonate activities against pitting corrosion is determined. In clay water at 90/sup 0/C, Ti and Ti-Pd show very high passivation aptitude and a broad ...

Energy Technology Data Exchange (ETDEWEB)

The goal of the present work has been to clarify the influence of sulphate ions on the oxide films formed on stainless steel and Ni-based alloys in simulated crack chemistry conditions using different ex situ analytical techniques. The main observations of this work can be summarised as follows: The thickness of the films formed in simulated oxygen-free crack chemistry conditions during an exposure of circa 4 days varies roughly in the range 200..500 nm, which corresponds to observations reported in the literature [2]. The presence of 10000 ppb sulphate ions in simulated crack tip conditions seems to lead to a considerably lower thickness of the oxide films when compared to sulphate-free conditions. The presence of 10000 ppb sulphate ions leads also to considerable changes in the morphology of the oxide crystals on the material samples. In the absence of sulphate the outer oxide layer contains elongated round-edged ...

British Library Electronic Table of Contents (United Kingdom)

Si nanocrystal floating gate MOS capacitors were formed on p-Si (100) wafers by thermal plasma jet (TPJ) annealing of SiO2/SiOx /SiO2/Si(100) stacked structure. The chemical composition of SiOx layer was controlled by changing the SiH4, He, and O2 gas flow ratio during plasma enhanced chemical vapour deposition. The MOS capacitors showed clear hysteresis in capacitance-voltage (CV) characteristics after TPJ annealing. The hysteresis width shows maximum value when initial composition x =1.7, which shows the maximum photoluminescence (PL) intensity. The maximum hysteresis width of 6.8 V was observed with gate voltage swept between 20 and -20 V in x = 1.7 sample. The result means 7.4 x 1012 cm-2 carriers are injected to or emitted from Si nanocrystals. The duration of 1 V shift in flatband vo...

Energy Technology Data Exchange (ETDEWEB)

Multi-walled carbon nanotubes (MWNTs) were modified with poly(hexamethylene adipamide) (also known as Nylon 66) via a controlled polymer solution crystallization method. A 'nanohybrid shish kebab' (NHSK) structure was found wherein the MWNT resembled the shish while Nylon 66 lamellar crystals formed the kebabs. These Nylon 66-functionalized MWNTs were used as precursors to prepare polymer/MWNT nanocomposites. Excellent dispersion was revealed by optical and electron microscopies. Nitric acid etching of the nanocomposites showed that MWNT formed a robust network in Nylon 66. Non-isothermal DSC results showed multiple melting peaks, which can be attributed to lamellar thickness changes upon heating. The crystallite sizes L{sub 100} and L{sup 010} of Nylon 66, determined by WAXD, decreased with increasing MWNT contents. Isothermal DSC results showed that crystallization kinetics increased first and then decreased with increasing MWNT contents in ...

Energy Technology Data Exchange (ETDEWEB)

Functionalization of carbon nanotubes is very challenging for their applications. The paper here describes a new method to functionalize multi-walled carbon nanotubes (MWCNTs) as specific affinity adsorbents. MWCNTs were acid purified and pretreated with (3-aminopropyl)-triethoxysilane (APTES) in order to introduce abundant amino groups on the surface of MWCNTs. After the conversion of amino groups to carboxyl groups by succinic acid anhydride, MWCNTs were attached to protein A or aminodextran using 1-ethyl-3,3' (dimethylamion)-propylcarbodiimide as a biofunctional crosslinker. The incorporation of aminodextran as a spacer arm noticeably increased the binding capacity of the APTES-modified MWCNTs for protein A. The application of affinity MWCNTs for purification of immunoglobulin G was then evaluated. The affinity of MWCNTs with AMD spacer exhibited a high adsorption capacity of {approx}361 {mu}g IgG/mg MWCNT (wet basis). About 75% of ...

International Nuclear Information System (INIS)

Alloy 800 and Alloy 600 are well known for their resistance to corrosion in an aqueous medium at high pressure and temperature, for which they have been widely used for more than 3 decades in different structural components of water refrigerated nuclear reactors, especially as material for the steam generator tubes (SG) in these nuclear plants. The SG tubes in the Atucha I and Embalse Nuclear Plants are made with Alloy 800. The speed of corrosion of these materials in a reactor's refrigerant medium, while very small is perfectly measurable and can be described by parabolic or logarithmic type kinetics. In other words this speed is high in the first states of growth during the formation of a protective oxide film but then drops to almost stationary values. One characteristic of these films is the formation of a double layer (or duplex): i) an internal adhering layer, of approximately constant thickness, formed by small microcrystals (#<=#0.05 ...

British Library Electronic Table of Contents (United Kingdom)

Solid-phase extraction and gas chromatography with electron-capture detection has been used for sensitive, simple, and reliable analysis of carfentrazone-ethyl residues in water. Carfentrazone-ethyl was enriched by use of multiwalled carbon nanotubes (MWCNT), a new adsorptive material. Several conditions affecting recovery of the analyte, for example polarity and volume of eluents, pH of water samples, and sample volume, were studied. Recovery from fortified samples, linear range, and limit of detection were evaluated. The results showed that MWCNT are an efficient SPE adsorbent for preconcentration of carfentrazone-ethyl in water. Under the optimized SPE conditions, recovery of carfentrazone-ethyl from fortified water was 81.49?91.08%, with RSD from 1.66 to 8.21%. The limits of detection ...

British Library Electronic Table of Contents (United Kingdom)

We demonstrate a novel cross-sectional deformation, called the radial corrugation, of multi-walled carbon nanotubes (MWNTs) under hydrostatic pressure. Theoretical analyses based on the continuum elastic approximation have revealed that MWNTs consisting of more than ten concentric walls undergo elastic deformations at critical pressure Formula Not Shown , above which the circular shape of the cross-section becomes radially corrugated. Various corrugation modes have been observed by tuning the innermost tube diameter and the number of constituent walls, which is a direct consequence of the core-shell structure of MWNTs. Cross-sectional views of MWNT under high hydrostatic pressure: elliptic deformation with the mode index n = 2 (left), and radial corrugations with n = 5 (center), and n = 6 ...

British Library Electronic Table of Contents (United Kingdom)

Abstract Dispersions of single-walled carbon nanotubes (SWNTs) in various surfactant solutions have been systematically evaluated as additives in MEEKC. The compounds examined were catechins, phenolic acids, and flavonoids. Compared with zwitterionic and neutral surfactants, the addition of anionic dispersion seemed to be better at separating the three types of analytes in microemulsion system. In order to achieve low operating currents, an in situ-synthesized surfactant system based on the combination of a long-chain alkyl acid with an organic base was used in MEEKC. The optimized buffer contained 0.5% (57-mM) ethyl acetate, 0.6% (30-mM) lauric acid, 4.0% (666-mM) propanol, 50-mM Tris solution, and 4.5-mg/L the dispersion of SWNTs. Under optimized conditions, the established method was ap...

British Library Electronic Table of Contents (United Kingdom)

Abstract Electronic structures of two representative zigzag and armchair models of aluminum phosphide nanotube (AlPNT) were investigated by density functional theory calculations. The structures were optimized and the bond lengths, tip diameters, band gaps, and dipole moments were calculated. Moreover, the quadrupole coupling constants (CQ) were calculated for the Al-27 atoms of the optimized structures. The same values of AlP bond lengths were calculated for both models. The larger value of band gap of armchair model than the zigzag model indicated the stronger dielectric property for the former model. The values of CQ(27Al) were the largest for the Al atoms placed at the tips of both zigzag and armchair AlPNT than other Al atoms, which could reveal dominant role of the Al atoms placed at...

Energy Technology Data Exchange (ETDEWEB)

Surface analytical studies of high nitrogen austenitic stainless steels exposed to deaerated 0.1M HCl have revealed that nitrogen alloying additions influence the composition of salt layers and the passive film/alloy interface. In this study the authors employ electrochemical techniques and variable angle X-ray Photoelectron Spectroscopy (XPS) to examine the passive films formed on a series of austenitic stainless steels, Fe18Cr8Ni, Fe18Cr8Ni0.2N, Fe20Cr20Ni, Fe20Cr20Ni6Mo and Fe20Cr20Ni6Mo0.2N, in acidic chloride aqueous solution. In addition, several other model alloys, Fe19Cr, Fe19Cr9Ni, Fe19Cr2.5Mo, and Fe19Cr9Ni2.5Mo, were examined before and after electrochemical surface nitriding, a technique proven to have an effect analogous to N alloying. It was shown that nitrogen, nickel and molybdenum additions independently and in certain combinations stimulate selective dissolution of iron, resulting in a significant ...

International Nuclear Information System (INIS)

Research highlights: ? Correlations between microstructure and internal stress during Ti anodising are established. ? Large internal compressive stresses are accumulated in the film during anodising upto 12 V. ?A transition from compressive to tensile stress is observed when the cell voltage exceeds 12 V. ? At 40 V, the oxide films consist of two regions with different compositions and microstructures. Crystallisation of amorphous to anatase TiO2 contributes to the compressive stress relaxation. - Abstract: The relationship between the microstructural and internal stress evolution during Ti anodising is discussed. Samples anodised galvanostatically to 12 V and 40 V, corresponding to different stages of the internal stress evolution, were examined by in-plane and cross-section transmission electron microscopy. Electron diffraction patterns have been complemented with stoichiometry data obtained from energy loss near edge ...

Energy Technology Data Exchange (ETDEWEB)

Aiming to realize ball bearings operable in a vacuum and under high temperature, silicon nitride (Si3N4) ceramic ball bearings were tested. The tested ball bearings were angular contact ball bearings composed of silicon nitride with sputtered molybdenum disulfide coating using a retainer of hot-pressed self-lubricating composite material. The time variation of the frictional torque was examined for the operations under the conditions at 500{degree}C in a vacuum at a rotational speed of 600 rpm and 50N thrust load for 5{times}10{sup 7}revolutions (1400 hours) and for 1.5{times}10{sup 8}revolutions (4200 hours). Excellent tribological performance was obtained. The ball bearings are lubricated with the molybdenum disulfide film at the initial stage of the operation and with a transfer film formed from the retainer material to the balls. In a test at 650{degree}C, low and stable frictional torque was observed up to 500 hours of ...

Energy Technology Data Exchange (ETDEWEB)

Thin films of new metastable materials from the system Ti-B-C-N were deposited on metallic substrates by d.c. magnetron sputtering in different Ar+N{sub 2} atmospheres. The multiphase compound targets used were based on various compositions on the TiC-TiB{sub 2} and TiB{sub 2}-C tie lines of the Ti-B-C phase diagram. The structure and chemical composition of the films were characterized by electron microprobe analysis, depth profiling Auger electron spectroscopy, X-ray diffraction and transmission electron microscopy. The hardness, critical load of failure and the tribological behavior of the coatings were investigated. Superhard single-phase crystalline metastable Ti-B-C-N layers with hardness values exceeding 5000 HV{sub 0.05} and extremely low sliding wear against 100Cr6 and Al{sub 2}O{sub 3} counterparts could be produced by reactive sputtering of various TiC-TiB{sub 2} targets in Ar+N{sub 2} ...

Energy Technology Data Exchange (ETDEWEB)

Advances in the theory and practice of stress corrosion cracking (SCC) are reviewed for the period 1965-1990. The proceedings of two landmark conferences are used as a basis for discussion: Ohio State University (1967) and Kohler, WI (1988). The discussion is developed around the following topics: metal-environment combinations, testing, fractography, metallurgical aspects, electrochemical aspects and crack chemistry, mechanisms, and prediction and mitigation. It is concluded that the main developments since 1967 are the recognition of the lack of specificity of SCC environments, the use of slow strain rate and fracture mechanics testing, quantitative SEM fractography, studies of grain boundary structure and compositions, transient electrochemistry of bare metal surfaces, measurement and modelling of crack chemistry, elaboration of several SCC models, including slip-dissolution and film induced cleavage, and mitigation by alloy development or ...

Energy Technology Data Exchange (ETDEWEB)

The morphological aspects of ternary phase formation during the Pd-GaAs reaction have been studied by application of transmission electron microscopy (TEM) and Rutherford backscattering (RBS) techniques. The TEM images show that the first product phase, ''phase I'', forms during deposition of Pd onto (100) GaAs and exhibits the preferred orientation (0001)/sub I/ approx. // (01 anti 1)/sub GaAs/. In the presence of unreacted Pd, the second phase, ''phase II'', nucleates at large-angle grain boundaries in the phase I film as the annealing temperature increases above approx.250C. Energy dispersive analysis of x-rays and RBS suggest the nominal compositions Pd3GaAs and Pd4GaAs for phases I and II, respectively.

Science.gov (United States)

The phase stability of silicides of Ni, Pt and Pd in contact with single crystal or amorphous silicon is examined. The presence of a particular silicide phase is identified by X-ray diffraction, and Rutherford backscattering is used to study composition. It is concluded that Pt or Pd silicides are suitable for Schottky barriers. Layers of silicon can be grown quickly by solid phase epitaxy at temperatures of 300-500C and using an intermediate metal film. Experimental results are reported. Doped layers have been obtained which have electrical characteristics suitable for the junctions in solar cells. The effects of impurities and orientation of the substrate on the growth kinetics are discussed.

International Nuclear Information System (INIS)

Some results and experimental procedures of laboratory are reported in the frame of researches conducted for the development of new nanostructured composite materials. These new materials, which are constituted by an organic phase: the polymer and an inorganic phase: the silicate, are being strongly investigated nowadays so it is expected that they could provide, among other, better electrical insulation properties and flame-delay in electrical and electronic applications. The laboratory experimental work has been developed from two families of polymers, thermoplastics and thermosets and clays silicates providing lamellar type. There are now some preliminary results, such as obtaining thin films of these nanocomposite materials, their complete characterization by X-ray diffraction, scanning microscopy and thermogravimetric analysis, they do well to wait for future research activities. (author)

British Library Electronic Table of Contents (United Kingdom)

The combined processes of plasma nitriding and cathodic arc deposition of (Ti,Cr,Nb)CN coatings were applied to HSS substrates. The nitrided layers, obtained in a mixture of H2 (70%) and N2 (30%) at two different temperatures (480^oC and 510^oC), were examined for the microhardness depth profiles. Characterization of the duplex coatings was performed by investigating elemental and phase composition, texture, hardness, friction and wear. XRD and XPS analyses revealed the formation of a mixture of a carbonitride fcc solid solution, in a dominant proportion, and metallic chromium. The film hardness was measured to be ~34GPa. The duplex (Ti,Cr,Nb)CN coatings exhibited superior tribological behavior as compared to both nitrided layers and non-duplex coatings.

International Nuclear Information System (INIS)

Marker experiments for studying the mass transport through a palladium silicide layer on a crystalline substrate during thermal oxidation at 700 to 850 deg C have been reported recently. In this work argon gas embedded in amorphous silicon during sputtering was implemented as the inert marker and the oxidation of PdSi was processed above 900 deg C. At this high-temperature oxidation silicon-rich silicide PdSisub(y), with y exceeding 5, may be obtained. This can be anticipated by considering the Pd-Si phase diagram which shows the liquid phase may appear at an annealing temperature above 892 deg C. As a result, a non-stoichiometric and non-uniform silicide layer may develop at the sample surface. Marker analysis showed that both palladium and silicon dissociated at the Pdsub(x)Si/ SiO_2 interface and moved to the substrate with the silicon being the dominant diffuser. The Rutherford backscattering spectra (RBS) showing the oxide film and ...

CERN Document Server

Three dimensional rotatory modes of oscillations in a one-dimensional chain of rodlike charged particles or dust grains in a plasma are investigated. The dispersion characteristics of the modes are analyzed. The stability of different equilibrium orientations of the rods, phase transitions between the different equilibria, and a critical dependence on the relative strength of the confining potential are analyzed. The relations of these processes with liquid crystals, nanotubing, and plasma coating are discussed.

Energy Technology Data Exchange (ETDEWEB)

The pitting resistance of Fe-Cr and Fe-Cr-Mo alloys has been correlated with characteristics of the passive films analyzed by Auger electron spectroscopy (AES). Increased film protectiveness as a result of increased Cr in the alloy can be directly attributed to Cr enrichment of the film and decreased film thickness. Increased Mo in the alloy or passivation at noble potentials promotes passive film resistance to breakdown, but neither does much to change the macrocharacteristics of the film. Rather, it is suggested that the roles of alloying and/or passivation conditions are related to the susceptibility and distribution of weak points of the film. In solutions in which pitting occurs, chloride is generally not incorporated into the film, suggesting that the role of halides is to interact with weak points of the ...

Energy Technology Data Exchange (ETDEWEB)

The friction and wear properties of glass fiber reinforced composites of nylons (nylon 6, nylon 66 and nylon 46) with different crystallinities due to their molecular structures were investigated by sliding them with alumina ceramics and using a pin-on-disk friction machine. The friction coefficients of the glass fiber reinforced nylons in oil were lower and more stable than those in air from the initial stage of friction. The transfer of nylon matrix to adhere onto the alumina surface in air was so much greater than in oil that the alumina surface could not be recognized. Consequently, a different between the friction and wear properties in air and in oil was resulted. Reinforcement of nylons with glass fiber remarkably improved their friction properties in oil by its lubricating action, while the wears were rather high contrary to what was expected. This tendency was conspicuous for nylon 46 with high crystallinity. Breakage and extracting of glass fibers from ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Science.gov (United States)

No abstract prepared.

Science.gov (United States)

Not Available

Science.gov (United States)

... Abstract : This report covers the investigation of an impingement-film cooling system designed to cool the exhaust ducts of turboshaft engines ...

Energy Technology Data Exchange (ETDEWEB)

The recent rapid progress in surface treatment techniques dictates that the titanium alloys should have an improved resistance to frictional wear without any loss of their high corrosion resistance. These requirements can be satisfied by producing surface layers of specified microstructure and phase composition. The present paper describes a modification of the plasma discharge nitriding treatment of titanium alloys, i.e. the glow discharge-assisted oxycarbonitriding, which by introducing oxygen, nitrogen and carbon into the surface zone of the layer [a Ti(NCO) type layer] improves its useful properties, primarily the resistance to frictional wear and the resistance to corrosion [T. Wierzchon, J. Sobiecki, Vacuum, 44 (1993) 975; T. Wierzchon et al., in: G. Hecht, F. Richter, J. Hahn (Eds.), Thin Films, DGM Informationgesellschaft, Germany, 1994, p. 195] [1:2]. This is because titanium shows a good affinity to oxygen, carbon and nitrogen, ...

Energy Technology Data Exchange (ETDEWEB)

Thin, lightweight, and flexible gas-diffusion electrodes (GDEs) based on freestanding entangled networks of single-walled carbon nanotubes (SWNTs) decorated with Ag nanoparticles (AgNPs) are tested as the air-breathing cathode in a zinc-air battery. The SWNT networks provide a highly porous surface for active oxygen absorption and diffusion. The high conductivity of SWNTs coupled with the catalytic activity of AgNPs for oxygen reduction leads to an improvement in the performance of the zinc-air cell. By modulating the pH value and the reaction time, different sizes of AgNPs are decorated uniformly on the SWNTs, as revealed by transmission electron microscopy and powder X-ray diffraction. AgNPs with sizes of 3-5 nm double the capacity and specific energy of a zinc-air battery as compared with bare SWNTs. The simplified, lightweight architecture shows significant advantages over conventional carbon-based GDEs in terms of weight, thickness and conductivity, and hence ...

Science.gov (United States)

Understanding the influence of interfacial structures on the nanoarchitecture mechanical properties is of particular importance for its mechanical applications. Due to a small size of constituting nanostructural units and a consequently high volume ratio of such interfacial regions, this question becomes crucial for the overall mechanical performance. Boron nitride bamboo-like nanotubes, called hereafter boron nitride nanobamboos (BNNBs), are composed of short BN nanotubular segments with specific interfaces at the bamboo-shaped joints. In this work, the mechanical properties of such structures are investigated by using direct in situ transmission electron microscopy tensile tests and molecular dynamics simulations. The mechanical properties and deformation behaviors are correlated with the interfacial structure under atomic resolution, and a geometry strengthening effect is clearly demonstrated. Due to the interlocked joint interfacial structures and compressive ...

International Science & Technology Center (ISTC)

Metal Matrix Composites on the Basis of Nano-Materials

International Science & Technology Center (ISTC)

Development of the Method of Electrodepositing Nanostructured Composite Coatings with Improved Engineering Properties

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The electrochemical behavior of the anti-thalassemia and anti-HIV replication drug, deferiprone, was investigated on a carbon nanotube-modified glassy carbon (GC-CNT) electrode in phosphate buffer solution, pH 7.40 (PBS). During oxidation of deferiprone, two irreversible anodic peaks, with E{sub 1}{sup 0}=452 and E{sub 2}{sup 0}=906mV, appeared, using GC-CNT. Cyclic voltammetric study indicated that the oxidation process is irreversible and diffusion controlled. The number of exchanged electrons in the electro-oxidation process was obtained, and the data indicated that deferiprone is oxidized via two two-electron steps. The results revealed that carbon nanotube (CNT) promotes the rate of oxidation by increasing the peak current, so that deferiprone is oxidized at lower potentials, which thermodynamically is more favorable. This result was confirmed by impedance measurements. The diffusion coefficient, electron-transfer coefficient and ...

International Nuclear Information System (INIS)

YBa_2Cu_3O_7_-_x thick films have been deposited on silver sheets and MgO single crystals by spray pyrolysis. Film texture is related to film thickness and sintering temperature. The X-ray intensity ratio of the 005 peak to the 110 peak is higher for thin films deposited at the higher temperatures. However, elevated temperatures promote copper diffusion and second-phase formation in films deposited on silver. Films deposited on MgO can have larger grain sizes and are more oriented than those deposited on silver.

International Nuclear Information System (INIS)

In this paper, we report the systematic investigation on the melt characteristics of silicon during laser thermal processing (LTP) of amorphous silicon (a-Si) gates on ultrathin gate oxides. LTP is used to reduce the gate depletion effect in advanced semiconductor devices. The influence of implantation-induced damage and chemical inhomogeneities on the melt behavior of ion-implanted a-Si is studied using in situ time-resolved reflectance (TRR) measurements and ex situ secondary ion mass spectrometry. The results from TRR measurements indicate the presence of a buried melt for a-Si implanted with B"+ at a subamorphizing dose. In contrast, such a melt behavior is not observed during LTP of undoped a-Si and a-Si implanted with As"+ at an amorphizing dose. We attribute the marked difference in the melt characteristics to the competitive effects between compositional inhomogeneities and the extent of amorphization in the a-Si layer. It should be noted that the ...

Energy Technology Data Exchange (ETDEWEB)

the medium to long freezing range alloys of aluminum such as A356, A357, A206, 319 for example are known to exhibit dispersed porosity, which is recognized as a factor affecting ductility, fracture toughness, and fatigue resistance of light alloy castings. The local thermal environment, for example, temperature gradient and freezing from velocity, affect the mode of solidification which, along with alloy composition, heat treatment, oxide film occlusion, hydrogen content, and the extent to which the alloy contracts on solidification, combine to exert strong effects on the porosity formation in such alloys. In addition to such factors, the availability of liquid metal and its ability to flow through the partially solidified casting, which will be affect by the pressure in the liquid metal, must also be considered. The supply of molten metal will thus be controlled by the volume of the riser available for feeding the particular casting location, ...

International Nuclear Information System (INIS)

The differential recoil cross sections of H have been determined for 1.5-3.0 MeV He"+ incidence. In order to obtain precise data, we have performed simultaneous detection and spectrum simulation of recoiled H and backscattered He. In addition, a careful cross check has been made by secondary ion mass spectrometry (SIMS). The present results have revealed a pronounced contribution from a nuclear short-range interaction. The He"+ energy and recoil angle dependence of the H recoil cross sections are well reproduced by adding the nuclear term, which is simply derived from effective range theory. Our computer simulation program of elastic recoil combined with Rutherford backscattering spectra makes it possible to determine the depth distributions of H together with other elements absolutely, without any ambiguities. The present elastic recoil analysis is employed to determine the H composition of amorphous Si(H) films deposited on Si wafers. An ...

Energy Technology Data Exchange (ETDEWEB)

Under severe operating conditions, such as starved lubrication, performance, service life, and reliability of rolling element bearings depend on the chemical and physical interactions between the contacting surfaces, the lubricant components, and the atmosphere. The IMKT{sup 1}, PI{sup 2}, and the imt{sup 3} have been cooperating on systematic investigations of interfacial interactions in high speed grease lubricated ball bearings. These include long time tests with complete bearings lubricated with greases of different composition under defined operating conditions, conducted at the IMKT, and chemical and physical characterizations of the running surfaces at the PI and imt. At the PI, in particular the chemical nature of the boundary layers has been investigated with time of flight secondary ion mass spectrometry (TOF-SIMS). The imt has been involved in the investigations by measuring the physical/mechanical properties of interacting surfaces at the ...

Energy Technology Data Exchange (ETDEWEB)

For the purpose of proposing it to ISO, the R and D were conducted of a new evaluation method of thermal properties of polymer materials. The FY 1999 results were summarized. In this fiscal year, the development of the ac Joule heating equipment was proceeded with based on the study at the technical committee, and the measuring device was installed. In the comparative measurement with conventional methods, study was proceeded with of the laser flash method, AC calorimetry method and specific heat measurement. In the technical survey, the developmental state of the ac method, especially, was examined as a testing method of thermal properties of polymer materials. It is in the stage of the basic research by keyword selection, and the search for literature is to be made in full scale. As to the needs in the industrial circle, as a result of the questionnaire survey made, it was found out that there were a wide variety of the needs for general-purpose/functional film ...

Energy Technology Data Exchange (ETDEWEB)

The passivation of low carbon steel was studied in aqueous solution of 0.5M Na[sub 2]SO[sub 4]+0.001M NaHSO[sub 3] (pH 3.5, 6.5 and 8.5) which can be considered as a model of acid rain. The used conversion electron Moessbauer spectroscopy (CEMS) with the complementary electrochemical investigations proved that the sulfite ions induce pitting corrosion at pH 3.5 and 6.5, while the measurements showed much weaker pitting at pH 8.5. The compositions and thicknesses of the passive films formed during the electrochemical treatments are determined from the CEM spectra. Only [gamma]-FeOOH was found on the surface of the samples at pH 6.5 and 8.5. Nevertheless, at pH 3.5 the sextet belonging to Fe[sub 3]C appears in the spectra, and also FeSO[sub 4].H[sub 2]O could be detected in low concentration. (orig.).

Energy Technology Data Exchange (ETDEWEB)

The physical properties of polymer blends consisting of one or more crystallizable components are affected by the microstructure of these materials. In particular, the degree of crystallinity can be influenced by processing parameters, and the crystallinity, as well as the phase distribution, may vary as a function of depth through an injection molded part Conventional x-ray diffraction techniques can provide information regarding both phase composition and degree of crystallinity, but, because of the relative transparency of these materials to wavelengths generally available in the laboratory, these techniques provide information representative of only the bulk. By employing parallel beam optics at varying grazing incidence angles, the x-ray sampling depth can be varied without loss of resolution. This technique can be used to vary the effective analysis depth from the top several hundred angstroms for low razing incidence to centimeters for transmission ...

Energy Technology Data Exchange (ETDEWEB)

The kinetics of passive film formation on iron in borate buffer solution has been studied at different anodic potentials. The process of film growth has been found to occur in four distinct stages. About 80-90% of the total film thickness formed in 1h grows during the initial two stages which last for only 1-3s (depending upon potential). The electric field strength across the film is not constant but decreases with progressing film growth. The thickness of the film determined ellipsometrically is less than that calculated from the electric charge consumed. The process of anodic film formation is accompanied by the dissolution of iron which occurs over the whole range of potentials.

International Nuclear Information System (INIS)

In this study, the corrosion behavior of commercially pure titanium (c.p. Ti), Ti-6Al-4V and five new experimental Ti-Cr alloys was evaluated through open-circuit potential (OCP) and potentiodynamic polarization measurement in an artificial saliva containing fluoride. Electron spectroscopy for chemical analysis (ESCA) was used to characterize the composition of the passive films on the alloy after potentiodynamic polarization measurement. It was found that in standard artificial saliva the OCP increases with higher Cr content in Ti-Cr alloys. In 0.5% NaF artificial saliva, the OCP decreases with decreasing Cr in Ti-Cr alloys, and all but Ti-5Cr remain consistently higher than those of c.p Ti and Ti-6Al-4V. Linear polarization results show that artificial saliva and artificial saliva containing 0.5% NaF result in different corrosion behavior in Ti-Cr alloys, c.p.Ti and Ti-6Al-4V. The Ti-Cr alloys had greater resistance to corrosion in the ...

International Nuclear Information System (INIS)

(Cu_4_7Zr_1_1Ti_3_4Ni_8)_1_0_0_-_xMo _x bulk metallic glasses (BMGs) with x = 0, 1 and 2 at.% and a bulk metallic glass matrix composite with x = 5 at.% were successfully prepared by water-cooled copper mold casting. The effect of the addition of a small amount of Mo on the glass forming ability (GFA), thermal properties of the base alloy (i.e. x = 0) were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and differential thermal analyzer (DTA). It is found that the addition of appropriate amount of Mo can enhance the GFA of the Cu-based BMG, as indicated by the increase in the reduced glass transition temperature T _r_g (=T _g/T _l) and the parameter #gamma# (=T _x/(T _g + T _l)) with the increase of Mo. On the other hand, the corrosion resistance of the Cu-based BMGs with different Mo contents was examined by electrochemical polarization and weight loss measurement in 1 mol/L H_2SO_4 and 1 mol/L NaOH solutions, respectively. It is ...

International Nuclear Information System (INIS)

A super-hydrophobic coating was prepared by combining a rigid base film with crater-like hemispherical holes and acicular nanoparticles. The acicular boehmite powder provides a high contact angle on the film surface. The rigid base film with crater-like hemispherical holes inhibits the rapid decrease of contact angle by surface rubbing. The combination of different roughness is an effective method for improving the abrasion resistance of super-hydrophobic films.

Energy Technology Data Exchange (ETDEWEB)

Individual nanoscale building blocks exhibit a wide range of size-dependent properties, since their size can be tuned over known characteristic length scales of bulk materials. In the last several years, the possibility of combining different materials in the form of two and three component nanoparticles (NPs) has been extensively explored. Also multi-component materials can be obtained via self-assembly of NPs from their binary colloidal mixtures. These new nanocrystal solids may possess tunable collective properties that originate from interactions between size and composition controlled building blocks. Exchange coupling between neighboring NPs of magnetically soft and hard materials enhances the magnetic energy product of the nanocomposite material. Randomly mixed solids of small and large semiconducting CdSe NPs revealed enhancement of photoluminescence intensity of large semiconductor particles accompanied by quenching of photoluminescence of the small ...

International Nuclear Information System (INIS)

Pitting crevice and intergranular corrosion resistances of titanium-modified low-carbon austenitic stainless steel with a nominal composition of 15% Cr, 15% Ni, 0.24% Ti and 2.5% Mo were found superior to conventional type 316 SS. Potentiodynamic anodic polarization studies in a neutral chloride medium (0.5M NaCl solution) and the immersion studies in boiling solution containing (by wt%) 11% H_2SO_4 + 3% HCl + 1% CuCl_2 + 1% FeCl_3 for 24 h showed higher critical pitting and crevice potentials and lower corrosion rate values respectively. The elemental composition across the pit sites was also determined by EPMA analysis. Sensitization studies carried out by following ASTM A262 practices A and E and electrochemical potentiokinetic reactivation (EPR) tests on this alloy heat treated at 923 K for 1 and 50 h showed a better resistance to intergranular corrosion than that for conventional type 316 SS. From the results available, the most likely ...

International Nuclear Information System (INIS)

The creep characteristics of alloy 800 at temperatures around 600"0C are greatly affected by the composition and treatments in the final stages of manufacture. Short-term and creep properties of alloy 800 at 600"0C are described for six melts covering the carbon range 0.054-0.078%, the titanium range 0.23-0.57% and the aluminium range 0.17-0.52%. The properties are related to the alloy chemistry and the microstructure. It is shown that homogeneously nucleated #gamma#'-precipitates are the main cause of low ductility in alloy 800 but there is also some influence of, for instance, grain boundary M_2_3C_6 films and discontinuous precipitation of Ni_3Ti or M_2_3C_6 in grain boundaries. The extent of #gamma#'-precipitation is controlled primarily by the (Ti+Al)-content. To avoid #gamma#' and ensure a high creep ductility the (Ti+Al)-content should be limited to 0.70-0.75% for alloy 800 with a carbon content of 0.054-0.078% and solution annealed at ...

British Library Electronic Table of Contents (United Kingdom)

Metallic Zn films were deposited on glass substrates by electron-beam evaporation. ZnO films were synthesized by thermal oxidation of Zn metallic films in air. At the annealing temperature of 550 ?C, ZnO nanowires appeared on the surface, which mainly result from the decrease of oxidation rate. A ZnO ultraviolet photodetector was fabricated based on a metal-semiconductor-metal planar structure. The detector showed a large UV photoresponse with an increase of two orders of magnitude. It is concluded that promising UV detectors can be obtained on ZnO films by thermal oxidation of Zn metallic films. The ways of performing spectral response measurements for polycrystalline ZnO films are also discussed.

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Manufacture of cadmium sulfide thin film solar cells

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As thin films become increasingly popular (for solar cells, LEDs, microelectronics, batteries), quantitative morphological information is needed to predict and optimize the film's electronic, optical and mechanical properties. This quantification can be obtained quickly and easily with X-ray diffraction using an area detector and synchrotron radiation in two simple geometries. In this paper, we describe a methodology for constructing complete pole figures for thin films with fiber texture (isotropic in-plane orientation). We demonstrate this technique on semicrystalline polymer films, self-assembled nanoparticle semiconductor films, and randomly-packed metallic nanoparticle films. This method can be immediately implemented to help understand the relationship between film processing and microstructure, enabling the development of ...

International Nuclear Information System (INIS)

Fe-Cr amorphous films have been formed by both in situ evaporation of multilayered films and ion beam mixing in a target chamber of a 200 keV implanter. The effects of Cr content and ion irradiation on the amorphization of films were examined by transmission electron microscope (TEM). Corrosion of film was investigated by means of a potential dynamic polarization. Corrosion resistance of amorphous film in 0.5 mol H-2SO-4 solution is considerably increased than that of pure iron. Using X ray photoelectron spectroscopy (XPS) corrosion resistance in atmosphere of amorphous Fe-Cr passive films formed by P"+ mixing was studied. Results show that the richness of Cr and P exist at the surface of Fe-Cr film.

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Sputtering of glass coatings on cadmium sulfide thin film solar cells

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Short note.

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KoreaScience (Korea)

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This paper reports that the point defect model for steady-state passive films formed anodically on metal s in aqueous environments has been extended to include irreversible dissolution of the film and the irreversible generation and annihilation of cation and oxygen vacancies at the metal/film and film/solution interfaces. THe model yields a number of diagnostic criteria that can be used to identify the majority (vacancy) charge carrier and to characterize the kinetic nature of the interfacial vacancy generation and annihilation processes. We use these criteria to show that the steady-state passive film that forms on nickel in acidic phosphate buffer solutions is a cation conductor and that cation transport from the metal to the solution involves irreversible ejection of cations from the film. On the other hand, the passive film that forms ...

International Nuclear Information System (INIS)

The comprehension of passivity and its protective character against corrosion is closely connected with the electronic properties of passive films. Passive films formed anodically on carbon steel in borate/boric acid solution, pH 9.2, have been characterised by electrochemical impedance spectroscopy (EIS). Mott-Schottky plots and impedance measurements were made on films formed at different potentials and times. The investigation allowed the determination of the semiconductive properties of the films. The results of the capacitance response indicate that the passive films behave like highly doped n-type semiconductors, showing that the passive film properties are dominated by iron. The value of donors density (N _D) for the passive film is of the order of 10"2"1 cm"-"3 and decreases with increasing formation time and potential, indicating ...

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... at the end of this report. A. Low-Velocity Impact of Composite Sandwich Panels In 2007, the PI developed analytical solutions ...

Energy Technology Data Exchange (ETDEWEB)

MINEQL is a subroutine package to calculate equilibrium composition of an aqueous system, accounting for mass transfer.

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... Abstract : High temperature testing of graphite/epoxy laminates and composite sandwich panels was performed while the Shuttle was on orbit to ...

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the progressive simplification of composite sandwich panels. The equations ... The thermal and structural behavior of composite sandwich panels with a ...

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... polypropylene, polylactic acid and polyvinyl chloride to form wood plastic composites (WPC). WPCs have seen a large growth in ... ...

British Library Electronic Table of Contents (United Kingdom)

The interaction between molecules and solid surfaces plays important roles in various applications, including catalysis, sensors, nanoelectronics, and solar cells. Surprisingly, a full understanding of molecule-surface interaction at the quantum mechanical level has not been achieved even for very simple molecules, such as water. In this mini-review, we report recent progresses and current status of studies on interaction between representative molecules and surfaces. Taking water/metal, DNA bases/carbon nanotube, and organic dye molecule/oxide as examples, we focus on the understanding on the microstructure, electronic property, and electron-ion dynamics involved in these systems obtained from first-principles quantum mechanical calculations. We find that a quantum mechanical description ...

International Nuclear Information System (INIS)

Surface-sensitive UV photoelectron yield spectroscopy was employed to study electron acceptor levels at surfaces of chalcopyrite structure Cu-In-Se thin films. Surface Fermi level pinning was observed for Cu-rich films. Shallow acceptor levels ascribable to defects Cu_I_n and V_C_u were observed for near-stoichiometric and In-rich films respectively. (orig.).

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Energy Technology Data Exchange (ETDEWEB)

Only two years ago, plastic film recycling was considered an onerous task. Different resins had to be identified, colors had to be separated, and minute contaminants had to be weeded out almost by hand to produce a quality material. But the tide of plastic film recycling is changing now that new technologies have emerged and more organized collection infrastructure have been developed. Today, plastic film recycling maintains a lucrative market for those with the right combination of equipment and know-how.

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The authors study the nonuniformity of a-Si:H films obtained by the method of vacuum condensation, with the help of x-ray small-angle scattering (SLS) and transmission electron microscopy. Films of hydrogenated amorphous silicon are greatest interest, because the electronic properties of this material can be controlled by doping. As a result of the compensation of the ruptured bonds, and possibly, effects of melting, the properties of such films are analogous to those of singlecrystalline silicon. XLS enables a quantitative determination of the prameters of the regions of low electron density (RLD) in such objects.

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Energy Technology Data Exchange (ETDEWEB)

Short communication.

Energy Technology Data Exchange (ETDEWEB)

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Energy Technology Data Exchange (ETDEWEB)

Passive films formed on stainless steels in a borate buffer solution (pH 9.2) have been investigated by capacitance measurements and photoelectrochemistry. The study was carried out on films formed on AISI type 304 and 316 stainless steels and high purity alloys with differing chromium, nickel, and molybdenum contents. Complementary research by Auger analysis shows that the passive films are composed essentially of an inner chromium region in contact with the metallic substrate and an outer iron oxide region developed at the film/electrolyte interface. The semiconducting properties of the passive films are determined by those of the constituent chromium and iron oxides which are of p-type and n-type, respectively. Thus the influence of the alloying elements on the semiconducting properties of the passive films is explained by changes in the electronic structure ...

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X-Ray reflectivity has been used to investigate the microstructural changes of solution-cast stearic acid films before and after immersion in CoCl{sub 2} solutions. Before immersion, the films possess a well-defined layered structure with an interlayer spacing of 4.01{+-}0.05 nm. After the films were immersed in the CoCl{sub 2} solutions, a new set of equidistant diffraction peaks emerge, the corresponding interlayer spacing of which is 5.13{+-}0.05 nm. The X-ray photoelectron spectra of the films indicate the existence of cobalt ions inside the films after immersion. It is concluded that the permeation of the cobalt ions into the hydrophilic interlayer causes the stearic acid molecules to reorient perpendicular to the films, resulting in the increase of interlayer spacing and the roughening of the interfaces.

International Nuclear Information System (INIS)

The total hemispherical emittance of an oxide film that formed on 6061-T6 aluminium alloy parts in the Tower Shielding Reactor-II at Oak Ridge National Laboratory was measured from 295 to 773 K using an emissometer and/or a calorimeter. The emittance of this film was critically needed for heat transfer calculations in a simulated loss-of-coolant accident of the reactor. X-ray diffraction analysis identified the film as boehmite (Al_2O_3 x H_2O), which dehydrated to alumina (Al_2O_3) upon heating above 473 K. The measured emittances for the alumina film are in excellent agreement with published values for anodized aluminum films and for bulk alumina. Published values of the emittance of boehmite could not be found for comparison, but evidence is presented that some anodization processes for aluminum yield boehmite and not alumina films.

Science.gov (United States)

Critical power at boiling transition is an important factor in a boiling water reactor (BWR) fuel bundle design. Boiling transition under high quality accounts for dryout as the result of the complete disappearance of film flow on a fuel rod. This liquid film vanishing process can be calculated by the liquid film model, which takes into account the evaporation due to heat from the rod surface, liquid film entrainment by steam flow, and liquid droplet deposition. It is known that spacers affect liquid film entrainment and liquid droplet deposition, so the detailed study of spacer effects on hydrodynamic characteristics is necessary for critical power prediction based on the film flow model. Many studies have been conducted to examine spacer effects on liquid film flow. However, most of them are restricted to simple test sections such as a ...