bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermogravimetric Thin Aqueous Film Corrosion Studies of Alloy 22; Calcium Chloride Solutions at 150°C and Atmospheric Pressure
Authors: Hailey Phillip , Gdowski Greg 
Published: April 2011

ABSTRACTThe extent of reaction of alloy 22 with limited amounts of aqueous calcium chloride (CaCl2) was investigated. Alloy 22 is a highly corrosion-resistant nickel-chromium-molybdenum-tungsten alloy. Specimens were polished to a mirror finish prior to aerosol salt deposition. An aqueous film was formed on the specimen surface by deliquescence of deposited CaCl2 at 150°C and 22.5% relative humidity (RH). The reactant gas was a continuous flow of purified humidified laboratory air. The reaction progress as a function of time was continuously measured in-situ by a microbalance. An initial weight gain due to CaCl2 deliquescence was observed. A steady weight loss was observed over the next 24 hours, after which no further weight change was apparent. During the period of weight loss, white precipitates formed and the specimen surface became visibly dry. Post-test analyses indicated that the precipitates consisted of calcium, chloride, and oxygen.
Effect of Anions on the Fluoride Corrosion of Titanium-Grade 7
Authors: Pulvirenti A. L. , Needham K. M. , Adel-Hadadi M. A. , Wong D. S. , Barkatt A. , Marks C. R. , Gorman J. A. 
Published: April 2011

ABSTRACTThe effects of chloride, sulfate, and nitrate on the fluoride ion local attack of Ti-Grade 7 (Ti-7: UNS R52400) were investigated. It was observed that a chloride: fluoride ratio of as high as 10 : 1 by mole was necessary to produce visible severe attack in immersion tests. Localized attack on Ti-7 was most severe at approximately 120°C, and at neutral pH. However, electrochemical studies detected that a narrowing of the passive region can occur at chloride: fluoride ratios as small as 1.1 : 1 by mole. The addition of sulfate did not significantly inhibit pitting or stress corrosion cracking of Ti-7 U-bends. However, the addition of nitrate is suspected to act as an effective inhibitor.
Effects of Fluoride and other Anions on the Corrosion of Alloy 22
Authors: Pulvirenti A. L. , Needham K. M. , Adel-Hadadi M. A. , Barkatt A. , Marks C. R. , Gorman J. A. 
Published: April 2011

ABSTRACTSamples of Alloy 22 were tested in solutions containing various anions in order to determine their effect on the corrosion of the alloy. It was found that Alloy 22 is relatively corrosion resistant in HCl and HNO3 at pH 1 and 160°C (general corrosion rates on the order of 10 μm/year), but more susceptible to phosphoric acid, especially under reducing conditions. The presence of fluoride raised the corrosion rate of Alloy 22 to the order 1 mm/year at pH 1, and fluoride is still active towards Alloy 22 at pH levels as high as 3.5. Samples tested in solutions of 1000xJ13 in which the pH was altered during testing showed an increase in corrosion rate over solutions of constant pH. Preliminary electrochemical tests suggest that nitrate may be an effective corrosion inhibitor in fluoride containing solutions, while sulfate is not.
Leaching of Spent Fuel under Anaerobic and Reducing Conditions
Authors: Albinsson Yngve , Ödegaard-Jensen Arvid , Oversby Virginia M. , Werme Lars O. 
Published: April 2011

ABSTRACTSweden plans to dispose of spent nuclear fuel in a deep geologic repository in granitic rock. The disposal conditions allow water to contact the canisters by diffusion through the surrounding bentonite clay layer. Corrosion of the canister iron insert will consume oxygen and provide actively reducing conditions in the fluid phase. Experiments with spent fuel have been done to determine the dissolution behavior of the fuel matrix and associated fission products and actinides under conditions ranging from inert atmosphere to reducing conditions in solutions. Data for U, Pu, Np, Cs, Sr, Tc, Mo, and Ru have been obtained for dissolution in a dilute NaHCO3groundwater for 3 conditions: Ar atmosphere, H2atmosphere, and H2atmosphere with Fe(II) in solution. Solution concentrations forU, Pu, and Mo are all significantly lower for the conditions that include Fe(II) ions in the solutions together with H2atmosphere, while concentrations of the other elements seem to be unaffected by the change of atmospheres or presence of Fe(II). Most of the material that initially dissolved from the fuel has reprecipitated back onto the fuel surface. Very little material was recovered from rinsing and acid stripping of the reaction vessels.
Rapid Manufacturing with Direct Metal Laser Sintering
Authors: Lind J-E. , Hanninen J. , Kotila J. , Nyrhila O. , Syvanen T. 
Published: April 2011

ABSTRACTThe term Rapid Manufacturing is today very often used as a substitute for Rapid Prototyping, because the manufacturing processes and materials have developed so much that the parts produced with the machines can even be used as functional production parts. For Direct Metal Laser Sintering (DMLS) this was enabled by the introduction of the powders for 20 micron layer thickness; steel-based powder in 2001 and bronze-based powder in 2002. Successful rapid manufacturing with DMLS does not only mean the reduction of layer thickness, but it is a sum of many factors that had to be optimized in order to make the process work with the 20 micron layer thickness: the metal powder behavior in very thin layers is not the same as with thicker layers, the demands for the support structures are higher and the possibility of using multiples of the layer thickness gives additional freedom. By optimizing the process parameters the UTS values for the steel-based powder increased up to 600 MPa and for the bronze-based powder up to 400 MPa. At the same time the surface roughness (Ra) values after shot peening were 3 microns and 2 microns, respectively. Although using thinner layers also increases the building time the advantage is gained in drastically reduced finishing times due to increased surface quality and detail resolution. Typical geometries produced by DMLS are difficult-to-manufacture components and components typically produced by P/M or even by die-casting. The paper covers the development aspects in both material and process development and also presents some realized case studies.
Computational Design, Freeform Fabrication and Testing of Nylon-6 Tissue Engineering Scaffolds
Authors: Das Suman , Hollister Scott J. , Flanagan Colleen , Adewunmi Adebisi , Bark Karlin , Chen Cindy , Ramaswamy Krishnan , Rose Daniel , Widjaja Erwin 
Published: April 2011

ABSTRACTAdvanced and novel fabrication methods are needed to build complex three-dimensional scaffolds that incorporate multiple functionally graded biomaterials with a porous internal architecture that will enable the simultaneous growth of multiple tissues, tissue interfaces and blood vessels. The aim of this research is to develop, demonstrate and characterize techniques for fabricating such scaffolds by combining solid freeform fabrication and computational design methods. When fully developed, such techniques are expected to enable the fabrication of tissue engineering scaffolds endowed with functionally graded material composition and porosity exhibiting sharp or smooth gradients. As a first step towards realizing this goal, scaffolds with periodic cellular and biomimetic architectures were designed and fabricated using selective laser sintering in Nylon-6, a biocompatible polymer. Results of bio-compatibility and in vivo implantation studies conducted on these scaffolds are reported.
Evaluating the Mechanical Properties of MEMS by Combining the Resonance Frequency and Microtensile Methods
Authors: Son Dongil , Kim Jong-jin , Kim Dong Won , Lim Tae Won , Kwon Dongil 
Published: April 2011

ABSTRACTTensile, fracture and fatigue properties of single- and polycrystalline silicon and LIGA-Ni were evaluated by the resonance frequency and microtensile methods. A new method for evaluating the fracture toughness that combines these two methods was proposed. A pre-crack was generated in an electrostatically driven test specimen and a load was applied by piezoelectrically driven microtensile equipment. Before the microtensile test, a new surface micromachining technique including a two-step sacrificial layer removal was used. The pre-cracked specimen was attached to microtensile equipment by a UV-adhesive glass grip. The fatigue pre-crack was successfully introduced and the fracture toughness could be derived on the basis of fracture mechanics. The fracture toughness of the pre-cracked specimen was relatively low compared with that of the notched specimen, so that we were able to determine the effect of the notch tip radius. The fatigue properties of LIGA-Ni film were also evaluated. A tensile-tensile fatigue load was applied by a piezoelectric actuator, and real-time load-displacement curves were displayed via computer. The dependence of S-N curves, crack propagation rates and fatigue-notch factor on the applied load for 10 μm Ni film was analyzed.
Semiconductor surface – molecule interactions: a case study in the wet etching of InP by α-hydroxy acids
Authors: Bandaru Prabhakar 
Published: April 2011

ABSTRACTThe controllable etching of InP semiconductor surfaces is desired in removing damaged layers for facilitating regrowth and obtaining good electronic properties. We have observed that organic acids (α-hydroxy acids: tartaric, lactic, citric and malic) used in conjunction with HCl to etch (100) InP result in smoother and defect free surfaces, in comparison to etches based on inorganic acids alone. The chelating action of the organic acids aids in efficiently removing In from the surface. Based on these results, it is hypothesized that a consideration of the energy levels of the semiconductor and adsorbed molecules could help in devising new semiconductor etchants.
Thin-Film Electrostatic Actuators on Flexible Plastic Substrates
Authors: Gaspar J. , Chu V. , Conde J. P. 
Published: April 2011

ABSTRACTThin-film silicon micromachined bridge actuators are fabricated at temperatures below 110°C on flexible polyethylene terephthalate plastic substrates. The micromechanical structures are electrostatically actuated both at the resonance frequency and at below-resonance frequencies, and the resulting deflection is optically monitored. Deflections up to 100 nm are measured below the resonance frequency with subnanometric precision. Resonance frequencies in the MHz range are observed in vacuum with quality factors of the order of 100. The movement is studied as a function of the geometrical dimensions of the actuators, of the actuation voltage and of the measurement pressure. The experimental data are analyzed using an electromechanical model. The performance of hydrogenated amorphous silicon based resonators on PET substrates is compared to that of similar microstructures on glass substrates.
Characterization of Mechanical Properties of Silicon Nitride Thin Films for Space Applications
Authors: Chuang Wen-Hsien , Luger Thomas , Fettig Rainer K. , Ghodssi Reza 
Published: April 2011

ABSTRACTMechanical properties of micro-electro-mechanical systems (MEMS) materials at cryogenic temperatures are investigated to extend MEMS devices into space applications. A helium-cooled measurement setup mimicking the outer space environment is developed and installed inside a focused-ion-beam (FIB) system. T-shape, low-stress LPCVD silicon nitride cantilevers suspended on a silicon substrate are fabricated as the test structures using bulk micromachining technique. A lead-zirconate-titanate (PZT) translator and a silicon diode are utilized as an actuator and a temperature sensor in the measurement setup, respectively. The resonant frequencies of an identical cantilever with different “milling masses” are measured to obtain the thickness and the Young's modulus. Additionally, a bending test is performed to determine the fracture strength. From the experiments, the Young's modulus of LPCVD silicon nitride thin films varies from 260.5 GPa ± 5.4 GPa at room temperature (298 K) to 266.6 GPa ± 4.1 GPa at 30 K, while the fracture strength ranges from 6.9 GPa ± 0.6 GPa at room temperature to 7.9 GPa ± 0.7 GPa at 30 K.
Localized, In-Situ Vacuum Measurements For MEMS Packaging
Authors: Moelders Nicholas , Daly James T. , Greenwald Anton C. , Johnson Edward A. , McNeal Mark P. 
Published: April 2011

ABSTRACTMEMS devices have unique packaging considerations compared to conventional semiconductor devices. They tend to have relatively large die size and many architectures cannot tolerate elevated temperatures. Often these devices require a vacuum environment for efficient operation. While advances have been made in hermetic packaging of MEMS devices, vacuum packaging remains elusive. One significant problem in developing vacuum sealing has been the inability to determine, readily and non-destructively, the vacuum level inside the package. We have previously described the development of a silicon MEMS-based chip design, “SensorChip™,” with integrated photonic crystal and reflective optics, which uses narrow-band optical emission and absorption for selective identification of gas and chemical species. Because the power consumption required to maintain a specific temperature is directly related to the vacuum level, these devices effectively serve as microscopic Pirani gauges – local vacuum sensors in the moderate vacuum range (0.01 to 1.0 torr) of interest to MEMS devices. Using the membrane itself as a vacuum gauge during sealing has proven to be an invaluable tool in developing a robust vacuum seal in a leadless chip carrier package. It has enabled us to optimize choice of design, materials and processing.
Effect of Polymer Substrates on Nano Scale Hot Embossing
Authors: Lee Jin-Hyung , Lim Hyun-Woo , Park Jin-Goo , Lee Eun-Kyu , Kim Yangsun 
Published: April 2011

ABSTRACTHot embossing has been widely accepted as an alternative to photolithography in generating patterns on polymer substrates. The optimization of embossing process should be accomplished based on polymer surface properties. Therefore, in this paper, polymers with different surface characteristic were selected and the surface properties of each polymers such as surface energy and adhesion force were investigated by contact angle and AFM. Based on these results, the imprinted nano patterns were compared. Silicon molds with nano size patterns were fabricated by e-beam direct writing. Molds were coated with self-assembled monolayer (SAM) of (1, 1, 2, 2H –perfluorooctyl)-trichlorosilane to reduce the stiction between molds and polymer substrates. For embossing, pressure of 500 psi, embossing time of 5 min and temperature of above transition temperature were applied. Mr-I 8010 polymer (Micro Resist Technology), Polymethylmethacrylate (PMMA 495k) and LOR (polyaliphatic imide copolymer) were used as substrate for hot embossing process development in nano size. These polymers were spun coated on the Si wafer with the thickness of 150 nm. The nano size patterns obtained by hot embossing were identified by atomic force microscopy without breaking the pattern and compared based on the polymer surface properties. The mr-I 8010 which has the lowest surface energy and adhesion force shows the best demolding property.
2D InP etching simulation under high density plasma of chlorine
Authors: Rhallabi A. , Liu B. , Marcos G. , Landesman J. P. 
Published: April 2011

ABSTRACTA gas phase kinetic model of chlorine in an ICP reactor (Inductive Coupled Plasma) combined with a surface model have been developed to study the etching profile evolution of InP material. A gas phase chemistry model is used to predict the main neutral and charged specie fluxes impinging upon etched InP surface. These particle fluxes are then injected as input parameters into both a Monte-Carlo sheath model and a 2D surface model to predict the etch profile topography. The coupling between the gas kinetic model, sheath and surface models allows a direct prediction of the InP etch profile evolution versus reactor parameters (pressure, source power, Cl2 flow rate, DC bias on the substrate‥). A parametric study is carried out to show the role of some plasma parameters on etch rate, anisotropy and adsorbed InP surface state by chlorine.
Evolution of Mesas on Si(111) Surface Under Sublimation: Nanofabrication through the Control of Atomic Steps
Authors: Chang Kee-Chul , Blakely Jack M. 
Published: April 2011

ABSTRACTHow the surface morphology of a low index crystal surface evolves under annealing below the roughening temperature is still being investigated both theoretically and experimentally. This research is needed to understand the stability of nanostructures and for the control of step array on surfaces for various technological applications.We have approached this problem from an experimental point of view by looking at the step morphology on the top of mesas patterned on Si(111) after flashing at 1200°C and annealing between 1000–1100°C. We find that after annealing, nanometer height ridges develop on the edges of the mesas except for one edge which becomes a source for steps advancing into the mesa top. The edge that does not develop a ridge is mainly determined by the initial miscut of the surface.We attempt to explain our results through step dynamics and present some applications of this phenomena in creating novel arrays of steps.
Advanced Anodic Bonding Processes For MEMS Applications
Authors: Dragoi V. , Lindner P. , Glinsner T. , Wimplinger M. , Farrens S. 
Published: April 2011

ABSTRACTAnodic bonding is a powerful technique used in MEMS manufacturing. This process is applied mainly for building three-dimensional structures for microfluidic applications or for wafer level packaging. Process conditions will be evaluated in present paper. An experimental solution for bonding three wafers in one single process step (“triple-stack bonding”) will be introduced.
Formation of Nanosized Metallic Ag Grains by Oxidation of Ag Single Crystals with Hyperthermal Atomic Oxygen
Authors: Li Long , Yang Judith C. 
Published: April 2011

ABSTRACTSilver single crystals (Ag(100), Ag(111)) were exposed to 5eV hyperthermal atomic oxygen, created by a laser detonation of molecular oxygen at a substrate temperature of 220°C for 7 hours. Oxide scales of more than ten microns formed on both Ag (100) and Ag (111) substrates. The microstructural investigation of the oxide layers by high resolution transmission electron microscopy (HRTEM) revealed that the “oxide” scales are predominately composed of nanosized polycrystalline silver grains (5–100nm) as well as a small amount of nanosized silver oxides. The results were remarkably different than the O2 oxidation. The HRTEM investigation suggested that the grains of polycrystalline silver were first carved off from the substrate into “oxide” scale by lattice expansion and decohesion, which are driven by atomic oxygen diffusion in Ag lattice, occupation of oxygen atoms at the interstitial sites of Ag lattice, and partially internal oxidation. The grains in the scale were also subject to continuing oxidations with the atomic oxygen--secondary poly-crystallization, and changed to smaller grains. The preferred oxidation fronts in silver lattice is along the {111} planes.
UV Curable Polymers with Organically Modified Clay as the Nanoreinforcements
Authors: Uhl Fawn M. , Hinderliter Brian R. , Davuluri Siva Prashanth , Croll Stuart G. , Wong Shing-Chung , Webster Dean C. 
Published: April 2011

ABSTRACTUV curable polymers are prevalent in microelectronic applications. Several advantages are associated with UV curing such as rapid cure, solvent free systems, application versatility, low energy requirements, and low temperature operation. To be used in electronics the films must posses the following attributes: high glass transition, barrier properties, low shrinkage, flexibility, and enhanced mechanical properties. The area of polymer-clay nanocomposites have been widely investigated by researchers and improved mechanical, thermal, and barrier properties were reported. Most researchers have attempted nanocomposite formation by melt mixing or in situ polymerization. Little is understood on UV curable nanocomposites. This paper seeks to examine nanoclay-containing polymers using organomodified montmorillonites in UV curable systems and the effects of such clay inclusions on the properties of UV cured films. By x-ray diffraction it appeared that intercalated structures were formed. In the case of an epoxy acrylate formulation an increase in glass transition temperature was observed for formulations containing clay.
Synthesis of mesoporous complex framework zirconium phosphates via organicinorganic nanocomposites: genesis of structure, adsorption and catalytic properties
Authors: Frolova Yulia V. , Sadykov Vladislav A. , Pavlova S. N. , Veniaminov S. A. , Bunina R. V. , Burgina E. B. , Kolomiichuk V. N. , Larina T. V. , Mezentseva N. V. , Fedotov M. A. , Volodin A. M. , Paukshtis E. A. , Fenelonov V. B. , Roy R. , Agrawal D. 
Published: April 2011

ABSTRACTThis work presents the first results of synthesis of framework binary phosphates of zirconium and transition metal cations (Co, Cu, Ce) via nanocomposites of starting inorganic salts with citric acid and studies of their structure genesis. Nanoparticles of layered Zr phosphates with typical sizes in the range of 18–24 Å are formedat the mixing stage. Less basic Cu and Co cations are mainly octa-coordinated with both phosphate groups of those nanoparticles and citric acid molecules. At subsequent thermal treatment, Cu and Co cations are incorporated within Zr phosphate nanoparticles acquiring a low coordination approaching a tetrahedral one while rearranging the nuclei structure into that of a framework type. Removal of citric acid by heating under air at 200–300°C preserves the size of nanoparticles while their ordered stacking forms mesoporous structure with a narrow pore size distribution ∼ 50 Å and specific surface area up to 200 m2/g after calcination at 600°C. The binary phosphates promoted by a small amount of Pt were found to be effective catalysts of NOx selective reduction by decane in the oxygen excess not subjected to coking with a high and stable performance at high space velocities in the presence of steam.
In-situ synthesis and magnetic properties of polystyrene/polypyrrole nanocomposite materials with uniformly dispersed iron nanoparticles
Authors: Srikanth H. , Poddar P. , Wilson J. L. , Mohomed K. , Harmon J. P. 
Published: April 2011

ABSTRACTMagnetic nanoparticles embedded in polymer matrices have excellent potential for electromagnetic device applications like EMI noise reduction. We have synthesized polystyrene (PS) and polypyrrole (PPy) composites by controllably dispersing bare and PS-coated Fe nanoparticles. These nanocomposites were processed as spin-coated thin films as well as in bulk form. The processing conditions were optimized to achieve good uniform dispersion of the nanoparticles in the polymer matrix. SEM scans revealed clustering of nanoparticles which was particularly evident at the surface in the conducting polymer nanocomposites. Magnetic hysteresis loop measurements indicate large coercivities associated with the clusters and surface oxidation of the Fe particles. Overall, the excellent dispersion coupled with reasonable control over magnetic properties achieved in our experiments is promising for electromagnetic applications of these materials.
Single-Walled Carbon Nanotube Rope for Gas Sensor Application
Authors: Lee J. W. , Choi Y. M. , Kong K. J. , Chang H. J. , Ryu B. H. 
Published: April 2011

ABSTRACTA chemical gas sensor with a novel pad pattern applicable to NH3, NO2, and H2 gas was developed based on single-walled carbon nanotube ropes. In this pattern named BCE (Barricade confronting electrode), several electrodes were located at the circumference of a sample and each pair of electrode tips was designed to confront to each other with a narrow interval. Several single-walled carbon nanotubes were shifted to the interval by the centrifugal force generated through the rapid rotation of a sample equipped on the spinner. Our device showed improved performance for NO2, NH3, and H2 gases compared with others in references.