bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanoscale Control of Friction and Chemistry on Silicon Surfaces
Authors: Baluch Andrew S. , Basu Rajiv , Guisinger Nathan P. , Reagan Kinser C. , Kramer Donald E. , Such Matthew W. , Hersam Mark C. 
Published: April 2011

ABSTRACTMany materials properties are tailored by controlling the chemical reactivity of surfaces. Consequently, through chemically active nanopatterning, surfaces can be engineered with nanoscale spatial resolution. This paper describes three techniques that enable the chemical reactivity of silicon surfaces to be customized down to the single molecule limit using scanned probe microscopy (SPM). All three techniques use chemically inert hydrogen passivated silicon as a starting substrate. Injected electrons and/or electric field from a conductive SPM tip locally disrupt the passivation, thus allowing the surface chemistry to be modified. Using ultra-high vacuum scanning tunneling microscopy, feedback controlled lithography leads to electron stimulated desorption of hydrogen from Si(100)-2×1:H with atomic resolution. The resulting dangling bonds preferentially react with gas phase molecules, enabling pre-determined self-directed growth of styrene molecular wires. In ambient conditions, conductive atomic force microscopy (cAFM) is used to grow nanoscale hydrophilic domains on Si(111):H via anodic field induced oxidation (FIO). Due to the chemical contrast between the hydroxyl terminated oxide and the hydrophobic Si(111):H surface, octadecyltrichlorosilane selectively binds to FIO nanopatterns. The final nanolithographic scheme, called liquid phase nanolithography (LPN), employs cAFM on surfaces submerged in organic solvents. By encapsulating the tip-sample junction in a solvent with low water and oxygen solubility, anodic oxidation is suppressed, thus enabling direct molecular attachment to the silicon surface from the liquid phase. In this work, LPN has been used to nanopattern undecylenic acid methyl ester. Nanoscale variations in the frictional properties induced by LPN and FIO are directly measured with lateral force microscopy. Through readily available and well-established chemical protocols, this nanolithography toolkit enables arbitrary materials, including polymers and biological molecules, to be covalently bound to silicon with nanometer spatial resolution.
Ag functionalized Carbon Molecular Sieves membranes for separating O2 and N2
Authors: Barsema J. N. , Balster J. , Van der Vegt N. F. A. , Koops G. H. , Jordan V. , Wessling M. 
Published: April 2011

ABSTRACTIn the last two decades substantial progress has been made in the preparation of Carbon Molecular Sieve (CMS) membranes for gas separation. Today, researchers actively study precursor materials and pyrolysis routes to fully explore the merits of CMS membranes. Successful separation of permanent gas mixtures in which the gaseous components posses only little to no affinity to adsorb onto the internal CMS surface relies highly on the exact tailoring of microsieving regions. Preparation of CMS structures, which are highly permselective towards one of such mixture components, is especially cumbersome if the molecular sizes differ only slightly (e.g. O2/N2).To facilitate the separation of O2 and N2 we have chosen to functionalize the carbon matrix. By introducing nano-sized (40 nm) metallic Ag-clusters, the affinity of the membrane matrix for O2 significantly increases. We have added a silver containing salt, AgNO3, to a solution of BMTA-TDI/MDI co-polyimide (P84, Lenzing) in NMP in the absence of light to obtain homogeneous flat film polymeric precursors. These precursors were pyrolysed, reducing Ag+ to Ag, at different temperatures (350, 500, 600, 700, and 800 °C) in a N2 atmosphere and characterized using Scanning Electron Microscopy, Atomic Force Microscopy, and gas permeation. Thermo Gravimetrical Analysis was used to follow the pyrolysis in detail. From this we observed an increase of the ideal separation factor of 1.6. Moreover, we observed an increase of the permeability to a maximum of 240 %.
Gas Permeation Characteristics and Stability of Composite Silica-Metal Oxide Membranes
Authors: Asaeda Masashi , Kanezashi Masakoto , Yoshioka Tomohisa , Tsuru Toshinori 
Published: April 2011

ABSTRACTIn order to improve the stability of silica membranes against water (vapor) some metal oxides were added to silica to obtain composite silica-metal oxide membranes by the sol-gel techniques. A Ni-doped silica membrane (Ni/Si=1/2) fired at 500°C showed a relatively large permeance of 1.5×10−5 [m3(STP)/(m2skPa)] with selectivity of 350 (H2/CH4), 4200 (H2/SF6) at 200°C and 100 (CO2/CH4) at 35 °C. After leaving the membrane in humid air (RH: 60%, 40°C) for 70 days, the permeance of H2 decreased by about 50% but the selectivity was improved to 930 for H2/CH4. And little change was observed in the activation energy for H2 permeation, while under the same conditions a silica membrane showed a quite large change in the activation energy from 3.1kJ/mol to 14kJ/mol. There is a possibility that metal oxides added to silica help prevent the densification of silica networks through which hydrogen and helium molecules can permeate.
The Hydrogen Permeability of Sulfur Resistant Palladium-Copper Alloys at Elevated Temperatures and Pressures
Authors: Howard B. H. , Cugini A. V. , Killmeyer R. , Rothenberger K. S. , Ciocco M. V. , Morreale B. D. , Enick R. M. , Bustamante F. 
Published: April 2011

ABSTRACTPd-Cu alloys are being considered for hydrogen membrane applications because of their resistance to sulfur poisoning. Therefore the permeance of Pd-Cu alloys containing 53, 60, and 80 wt% Pd has been determined over the 623 – 1173 K temperature range for H2partial pressure drops as great as 2.75 MPa. The results indicate that Pd-Cu alloy composition and thermal history influence membrane permeance. The 60%Pd-40%Cu alloy exhibited very high permeance at 623 K, although both the 53%Pd and 60% Pd alloys exhibited a distinct drop in permeability at higher temperatures due to the transition of the Pd-Cu crystal structure from bcc to fcc. Upon cooling the membrane back to 623 K, the permeability of the 60%Pd alloy was initially an order-of-magnitude less than its initial value, but the permeance increased steadily with time as the Pd – Cu crystal structure slowly reverted to bcc. The fcc 80%Pd alloy was less permeable than the bcc 60% Pd alloy at 623 K, but the 80% Pd alloy was more permeable than the fcc 60%Pd alloy at elevated temperatures.
Filtrate Flux and Sieving Characteristics of Virus Filtration Membranes
Authors: Zydney Andrew L. , Bohonak David M. 
Published: April 2011

ABSTRACTVirus filtration is increasingly used in the biopharmaceutical industry, but capacity and fouling remain problematic. Experimental studies were conducted in dead-end, stirred filtration cells with Viresolve 180 polyvinylidene fluoride membranes using the protein bovine serum albumin. Data were obtained for membranes in two different flow orientations, with the selective “skin” layer oriented on either the upstream surface or downstream relative to the fluid flow. Compaction of the substructure occurs when the skin layer is downstream, leading to a significant increase in membrane resistance. Concentration polarization in the bulk solution or membrane substructure caused a substantial increase in the protein sieving coefficient, with this effect being greatest when the flow entered through the substructure. Fouling is primarily due to the deposition of large protein aggregates. The effect of this fouling on the flux was reduced when the skin layer was oriented downstream since the substructure acted as a prefilter. These results demonstrate that the membrane morphology and orientation play a critical role in determining the overall performance of virus filtration membranes.
Comparison of Impact of Virgin Polymer Structure on Properties of Irradiated Membranes – Hydrogen Ion Irradiation on Polyimide Isomers
Authors: Xu Xinglong , Hu Ling , Ilconich J. 
Published: April 2011

ABSTACTThis study focused on the impact of virgin polymer structure and microstructure on the transport properties of irradiated polyimide. Two fluorine containing polyimide isomers (6FDA-6FpDA and 6FDA-6FmDA) that differ solely in the location of the linkage between the diamine and dianhydride residues were used for this study. While these polymers differ in the location of a single bond, the virgin transport properties are dramatically different. The para connected isomer (6FDA-6FpDA) has much higher permeabilities and lower selectivities than the meta connect isomer (6FDA-6FmDA). The pure gas permeabilities in polyimide-ceramic composite membranes following H+ ion irradiation over a wide range of doses will be compared for these polyimide isomers. In addition, the evolution in chemical structure was monitored using Fourier transform infrared spectroscopy (FTIR). These polymers exhibited different decay rate in chemical structure following ion irradiation. Interestingly, the evolution in gas transport properties of these polymers following H+ ion irradiation was also quite different. We will discuss how the microstructure would affect the gas permeation properties of ion beam modification of polymer.
Molecularly Imprinted Membranes Having Amphiphilic Scaffold Media for Target Molecule Recognition
Authors: Kobayashi Takaomi , Onodera Takashi , Ohta Michiyoshi 
Published: April 2011

ABSTRACTPolyacrylonitrile copolymer having amphiphilic octyl-dimetyl quarternized ammonium moiety was used as imprint scaffolding media for Theophylline (THO) adsorbent. The THO imprinted membranes were prepared by phase inversion technique; The polymer dimethylsulfoxide (DMSO) solution containing THO was cast and then phase-inversed in water to prepare THO imprinted membranes. After template extraction, adsorbent properties of THO were studied by heterogeneous binding experiments of THO and analogs such as caffeine, uracil, and theobromine. Results showed that imprinting effect was appeared in copolymer containing both octyl-hydrophobic group and positively charged ammonium groups.
Mechanical Behavior of Ternary and Quaternary Rual Alloys
Authors: Nandy T. K. , Feng Q. , Banerjee D. , Gigliotti M. F. X. , Pollock T. M. 
Published: April 2011

ABSTRACTThe mechanical behavior of RuAl-base intermetallic alloys with alloying additions of boron, niobium and platinum has been investigated. Compression tests have been performed at room temperature and 973 K. While the addition of alloying elements results in solid solution strengthening, the strain-rate sensitivity and the activation volumes do not show a significant variation, thereby suggesting that the macroscopic flow mechanisms are not strongly affected. Deformation substructure analysis of the niobium-containing alloy shows the presence of <100> and <110> dislocations, while the platinum-containing alloy additionally contains a significant density of <111> dislocations.
Microstructural Evaluation of LENS™ Deposited Nb-Ti-Si-Cr Alloys
Authors: Dehoff Ryan R. , Sarosi Peter M. , Collins Peter C. , Fraser Hamish L. , Mills Michael J. 
Published: April 2011

ABSTRACTNb-Ti-Si “in-situ” metal ceramic composites consist of Nb3Si and Nb5Si3 intermetallic phases in a body centered cubic Nb solid solution, and show promising potential for elevated temperature structural applications. The addition of Cr has also been shown to increase the oxidation resistance at high temperatures. In this study, the LENS™ (Laser Engineered Net Shaping) process is being implemented to construct the Nb-Ti-Cr alloy system from elemental powder blends. Advantages of the LENS™ process include the ability to produce near net shaped components with graded compositions as well as a more uniform microstructure resulting from the negative enthalpy of mixing associated with the silicide phases. This study focuses on characterization of the microstructure of the Nb-27Ti-5Si-10Cr (at%) system using SEM and TEM analysis.
Dislocation/Twin/Interface Interactions during Deformation of PST TiAl Single Crystals, an AFM Study
Authors: Chen Yali , Pope David P. , Vitek Vaclav 
Published: April 2011

ABSTRACTPST TiAl crystals oriented such that the deformation axis lies in the (111) interfacial planes have been deformed in compression. This deformation produces so-called “channeled flow” in which the strain perpendicular to the (111) interfaces is zero, while the other two strains are equal and opposite in sign. Thus the sample simply shortens axially and spreads laterally in the channels defined by the (111) interfacial planes. We have examined the fine structure of deformation bands on the free surface of these deformed samples using AFM to see how the deformation processes interact with the boundaries. By measuring the offset angle at the surface we have been able to show that not only is the macroscopic displacement vector parallel to the lamellar boundaries, but the total shear vector in each layer is also parallel to the lamellar boundaries. However these deformation bands have very different characters, requiring complex deformation processes at the boundaries in order to satisfy this requirement. Some consist of either just super dislocations or just ordinary dislocations with Burgers vectors lying in the interface. But others consist of a special combination of twinning and ordinary dislocations in fixed ratio, such that the net shear vector also lies in the boundary, even though the individual twinning and dislocation shear directions are inclined to it. This results in deformation that is homogeneous and completely ‘channeled’ inside each lamella with no shear vector perpendicular to the lamellar boundaries. We have also shown that the cooperative twinning and slip is homogeneous on the nano-scale, i.e., the twinning and slip occurs in the same volume of material.
Formation of β-Ti Phase in Multi-component Gamma Alloys
Authors: Kobayashi Satoru , Takeyama Masao , Motegi Takahiro , Hirota Noriaki , Matsuo Takashi 
Published: April 2011

ABSTRACTEffect of combined addition of elements on the formation of high-temperature β-Ti (bcc) phase in Ti-45Al-M1-M2 quaternary alloys has been examined by converting the quaternary system to quasi-ternary system using M1-equivalency of M2: [M1] eq = k [M2]. The k value is evaluated from the ratio of critical concentration, XcM, to form the β phase in the isothermal section of each ternary system at 1473 K: kM1/M2= XcM1/XcM2. In case that M1 and M2 are in the same group element, Mo-equivalency of Cr, kMo/Cr = 0.46 and Nb-equivalency of V, kNb/V = 0.57. The critical concentrations to form the β phase in the quaternary systems become lower than those estimated from these values, and the experimentally determined equivalencies become 0.8 and 1.0, respectively. These results suggest an existence of negative interaction between M1 and M2 to stabilize the β phase even if they were in the same group element. Experimentally determined quaternary phase diagram revealed that the combined addition makes the β+α two-phase region expand to lower temperatures, thereby effective in improving hot workability for development of wrought gamma alloys.
Micromechanisms of deformation in γ-TiAl
Authors: Veyssière Patrick , Chiu Yu-Lung , Grégori Fabienne 
Published: April 2011

ABSTRACTInvestigations conducted in our group on plastic properties of a variety of strained TiAl based alloys and resulting microstructures are reviewed. These include oriented single crystals of Al-rich γ-TiAl and semi-oriented polycrystals with γ + α2 lamellar structure. The wealth of micro-mechanisms encountered in this family of alloys is, to large extent, due to the decomposition of <011] dislocations: <011] ↔ 1/2<112] + 1/2<110]. This transformation sometimes introduces serious uncertainties as to which slip systems were actually operating during deformation. Another transformation involving decomposition is the formation of intralamellar networks during deformation. Mechanisms not involving decomposition include the trailing of faulted dipoles by <011] dislocations and the generation of arrays of prismatic loops of ordinary dislocations. The latter maneuver is at the origin of fundamental processes such as self-organisation in single slip in a variety of crystals.
Effect of Interphase Boundary Character on Mechanical Properties in NiAl(β) Bicrystals with Ni 3Al(γ') Precipitates along Grain Boundary
Authors: Sakata Toshiya , Yasuda Hiroyuki Y. , Umakoshi Yukichi 
Published: April 2011

ABSTRACTRole of the crystallography of Ni 3Al(γ') precipitates along grain boundaries of NiAl(β) in the mechanical properties was systematically investigated using β bicrystals with controlled orientations. γ' phase preferentially precipitated along βgrain boundaries showing a film-like shape. The selected variant of γ'-film satisfied the Kurdjumov-Sachs (K-S) relation with a neighboring βcrystal but it deviated from the relation with another adjacent βcrystal. In the course of tensile deformation at room temperature, fracture occurred preferentially at incoherent (β/γ') interphase boundary deviating from the K-S relation and the fracture stress decreased with increasing deviation angle. In contrast, the interphase boundary sliding occurred preferentially at irrational (β/γ') interface at 1073K. The sliding displacement increased with increasing deviation angle. Thus, the mechanical properties of β bicrystals with γ'-film were found to depend strongly on the interphase boundary character.
A1→D022Transformation and Multi-Variant Structure of Ni3V
Authors: Suzuki Akane , Takeyama Masao , Matsuo Takashi 
Published: April 2011

ABSTRACTThe formation mechanism and morphology of the tetragonal compound Ni3V (D022) quenched from the disordered fcc (A1) state have been examined by TEM using a Ni-25at%V. The alloy is fully transformed to D022in the quenched state. The resulting microstructure exhibits a fine brick-like “multi-variant structure (MVS)” consisting of one major and two minor variants withcaxes perpendicular each other, having coherent interfaces of {102)D022and {100)D022. The major variant particles with a quadrangular-prism shape are alternately arrayed with two minor variants, one parallel to {102)D022and the other {100)D022, respectively. The thermal APDs are formed in the all variants, but the average size within the major is larger than that in the minors. The c/a ratio of the D022in the MVS is 2.006, much smaller than the value (2.04) in equilibrium state. From all these facts, the transformation of A1→D022is assumed to proceed through a selective nucleation and growth of tetragonal A6 phase, followed by ordering to D022. The formation of the tetragonal phase produces an anisotropic strain field due to the contraction and expansion of theaandcaxes against the cubic matrix. The strain field makes {102)D022and {100)D022with the invariant lines become habit, and also drives the selective nucleation and growth of minor variants to minimize the elastic strain energy, thereby leading to the multi-variant structure.
Phase Constitution and Oxidation Resistance of B2 (Ir, Co)Al
Authors: Hosoda Hideki , Noma Hiroshi , Wakashima Kenji 
Published: April 2011

ABSTRACTB2 iridium aluminide (IrAl) is hopeful for use as an ultrahigh temperature oxidation resistant coating above 1600K. In this study, the effect of Co substitution for Ir on phase constitution, hardness and oxidation behavior was studied for IrAl alloys. Alloys of (Ir, Co)-50mol%Al with various Co contents were fabricated by Ar-arc melting followed by hot-forging at 1773K. Oxidation behavior was evaluated using thermogravimetry (TG) in Ar-67%O2 up to 1823K. XRD and SEM were also carried out for alloy characterization. It was found that a continuous B2 solid solution (Ir,Co)Al is formed between IrAl and CoAl. Depending on the Co concentration, the oxidation products identified after heating to 1873K in Ar-67%O2 were Ir, IrO2 and A2O3 and/or Co2AlO4. Thin and continuous Al2O3 layers were observed after isothermal oxidation at 1673K when Co content is more than 20mol%Co. In this case, the weight change by isothermal oxidation at 1673K becomes higher with decreasing Co content. The (Ir,Co)Al alloys containing 20–40mol%Co exhibit higher oxidation resistance than CoAl and IrAl, and thus oxidation resistance of CoAl is improved by Ir addition.
Processing and Characterizing RuAl Eutectics
Authors: Reynolds Todd , Johnson David 
Published: April 2011

ABSTRACTEutectic alloys in the Ru-Al-Mo system were directionally solidified by a cold crucible Czochralski technique. The solidification microstructures and composition of the phases were examined and used to estimate a partial liquidus projection. Preliminary results from compression and hardness testing indicate that the hardness of RuAl varies significantly with composition. The Ru-rich alloys in which RuAl is in equilibrium with the hcp (Ru,Mo) solid solution were found to have the lowest hardness values.
IC Component Level Failure Induced By Intermetallic Layer Structural Defects of Solder Joint
Authors: Sun Ming , Loo Mike , Zhao Lily 
Published: April 2011

ABSTRACTSolder joint has been widely used in microelectronics industry as an interconnect of Integrated Circuit (IC) chip and Printed Circuit Board (PCB). Frequently, a functional failure of the component on the system is a result of solder joint damage. Eutectic 63Sn/37Pb solder joint mechanical behaviors on Ni/Au plated copper pad and bare copper pad were experimentally investigated to address the effect of pad surface cleanness on the formation of intermetallic compound. The joints with thinner intermetallic compound layer resulted in a poor solder ball shear strength. Microstructural analysis revealed that the oxidations of Ni and Cu during substrate manufacturing contributed to the improper growth of intermetallic compound during assembly and reliability tests. In additions, the experimental results showed that the growth of the intermetallic compound layer were dependent not only on the time and temperature of solder reflow and testing, but also on the cleanness of the pad surfaces and available area for the diffusion of Ni in the case of Ni/Au plated copper pad, Cu in the case of bare copper pad and Sn in the joint area.
Defects Generated by Hydrogen Absorption/Desorption in Lani5 and Derivatives
Authors: Décamps B. , Joubert J.-M. , Cerny R. , Percheron-Guégan A. 
Published: April 2011

ABSTRACTThe combination of bright-field and weak-beam transmission electron microscopy (TEM) techniques has been used to analyse the dislocation systems activated in LaNi5 and derivatives after absorption/desorption hydrogen cycling.The TEM results are discussed and compared with those obtained from the modelling of the anisotropic diffraction peak broadening using only two dislocation slip systems of the hexagonal structure (1).
Enhanced Thermoelectric Properties of [Ca2CoO3-δ]0.62CoO2 Polycrystalline Bulk by Control of Microstructure and Oxygen Content
Authors: Sano M. , Horii S. , Matsubara I. , Funahashi R. , Shikano M. , Otzschi K. , Shimoyama J. , Kishio K. 
Published: April 2011

ABSTRACTWe report preparation of highly grain-aligned and densified [Ca2CoO3-δ]0.62CoO2 bulks and a change of thermoelectric performance for their bulks with different oxygen deficiencies (dgrl). The highly c-axis aligned and highly densified samples which showed low electronic resistivities at room temperature, were obtained by combination of magnetic alignment and spark plasma sintering methods. Electronic resistivity p and Seebeck coefficient S along the ab plane were systematically changed with oxygen contents and a power factor was consequently enhanced up to 3.5×10--6 Wcm-1K-2 at 300K for the sample annealed at 500°C in air. Moreover, the magnetic properties also showed a systematic change with oxygen contents.