Science.gov

Sample records for metal shaping processes

  1. Thermal analysis and evolution of shape loss phenomena during polymer burnout in powder metal processing

    NASA Astrophysics Data System (ADS)

    Enneti, Ravi Kumar

    2005-07-01

    Powder metallurgy technology involves manufacturing of net shape or near net shape components starting from metal powders. Polymers are used to provide lubrication during shaping and handling strength to the shaped component. After shaping, the polymers are removed from the shaped components by providing thermal energy to burnout the polymers. Polymer burnout is one of the most critical step in powder metal processing. Improper design of the polymer burnout cycle will result in formation of defects, shape loss, or carbon contamination of the components. The effect of metal particles on polymer burnout and shape loss were addressed in the present research. The study addressing the effect of metal powders on polymer burnout was based on the hypothesis that metal powders act to catalyze polymer burnout. Thermogravimetric analysis (TGA) on pure polymer, ethylene vinyl acetate (EVA), and on admixed powders of 316L stainless steel and 1 wt. % EVA were carried out to verify the hypothesis. The effect of metal powders additions was studied by monitoring the onset temperature for polymer degradation and the temperature at which maximum rate of weight loss occurred from the TGA data. The catalytic behavior of the powders was verified by varying the particle size and shape of the 316L stainless powder. The addition of metal particles lowered the polymer burnout temperatures. The onset temperature for burnout was found to be sensitive to the surface area of the metal particle as well as the polymer distribution. Powders with low surface area and uniform distribution of polymer showed a lower burnout temperature. The evolution of shape loss during polymer burnout was based on the hypothesis that shape loss occurs during the softening of the polymer and depends on the sequence of chemical bonding in the polymer during burnout. In situ observation of shape loss was carried out on thin beams compacted from admixed powders of 316L stainless steel and 1 wt. % ethylene vinyl acetate

  2. Development of a method for fabricating metallic matrix composite shapes by a continuous mechanical process

    NASA Technical Reports Server (NTRS)

    Divecha, A. P.

    1974-01-01

    Attempts made to develop processes capable of producing metal composites in structural shapes and sizes suitable for space applications are described. The processes must be continuous and promise to lower fabrication costs. Special attention was given to the aluminum boride (Al/b) composite system. Results show that despite adequate temperature control, the consolidation characteristics did not improve as expected. Inadequate binder removal was identified as the cause responsible. An Al/c (aluminum-graphite) composite was also examined.

  3. Properties of near-net shape metallic components made by the directed light fabrication process

    SciTech Connect

    Lewis, G.K.; Milewski, J.O.; Thoma, D.B.; Nemec, R.B.

    1997-10-01

    Directed Light Fabrication (DLF) is a process invented at Los Alamos National Laboratory that can be used to fuse any metal powder directly to a fully dense, near-net shape component with full structural integrity. A solid model design of a desired component is first developed on a computer work station. A motion path, produced from the solid model definition, is translated to actual machine commands through a post-processor, specific to the deposition equipment. The DLF process uses a multi-axis positioning system to move the laser focal zone over the part cross section defined by the part boundaries and desired layer thickness. Metal powders, delivered in an argon stream, enter the focal zone where they melt and continuously form a molten pool of material that moves with the laser focal spot. Position and movement of the spot is controlled through the post-processor. Successive cross-sectional layers are added by advancing the spot one layer thickness beyond the previous layer until the entire part is deposited. The system has 4 powder feeders attached for co-deposition of multiple materials to create alloys at the focal zone or form dissimilar metal joint combinations by changing powder composition from one material to another. Parts produced by the DLF process vary in complexity from simple bulk solid forms to detailed components fabricated from difficult to process metals and alloys. Parts have been deposited at rates up to 33 cm{sup 3}/hr with 12 cm{sup 3}/hr more typical. Feasibility of processing any metal ranging in melting point from aluminium to tungsten has been demonstrated. Mechanical properties for bulk DLF deposits of three alloy powders were measured for this study. Ti-6Al-4V and 316 stainless steel powders were fabricated into rectangular bar, and Inconel 690 powder was fabricated into a solid cylinder.

  4. Influence of surface processing on the fracture strength of structurally integrated PZT fibers in shaped sheet metal parts

    NASA Astrophysics Data System (ADS)

    Schmidt, Marek; Wittstock, Volker; Müller, Michael

    2015-03-01

    In the present state of the art, the function integration into lightweight metal structures is generally based upon adhesive bonding of sensors or actuators to the surface. A new technology enables a direct structural integration of lead-zirconatetitanate (PZT) fibers into local microstructures of metal sheets and subsequent joining by forming. This provides a complete functional integration of the piezoelectric ceramic in the metal for sensors and actuators purposes. In a further process step, the composite is shaped by deep drawing with a cup with double curvature radii of 100 mm into a complex 3D surface. During the shaping process it is expected that the PZT- fibers get damaged with the result of degradation of the piezoelectric function. This paper describes the application of various surface processing methods to improve the shaping behavior of the piezoceramic fibers. The production of interconnected parallel fibers is based on piezoceramic plates. The plates are treated by different surface processing. One experimental series is lapped and another series is extra polished by chemical mechanical polishing (CMP). The resulting plates were examined with regard to the fracture strength and the degradation of the piezoelectric properties during manufacturing and operation. It has been shown that the lapped and polished plates have a clearly better persistence with regard to the shaping processes compared to the unprocessed plates. The best results in this process were achieved by the polished plates, which is also transferable to the fibers. Furthermore, the piezoelectric characteristics were better preserved by the lapped and polished plates and fibers.

  5. Methodology development for the sustainability process assessment of sheet metal forming of complex-shaped products

    NASA Astrophysics Data System (ADS)

    Pankratov, D. L.; Kashapova, L. R.

    2015-06-01

    A methodology was developed for automated assessment of the reliability of the process of sheet metal forming process to reduce the defects in complex components manufacture. The article identifies the range of allowable values of the stamp parameters to obtain defect-free punching of spars trucks.

  6. Shaping metallic glasses by electromagnetic pulsing

    PubMed Central

    Kaltenboeck, Georg; Demetriou, Marios D.; Roberts, Scott; Johnson, William L.

    2016-01-01

    With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals. PMID:26853460

  7. Shaping metallic glasses by electromagnetic pulsing.

    PubMed

    Kaltenboeck, Georg; Demetriou, Marios D; Roberts, Scott; Johnson, William L

    2016-02-08

    With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals.

  8. Shaping metallic glasses by electromagnetic pulsing

    NASA Astrophysics Data System (ADS)

    Kaltenboeck, Georg; Demetriou, Marios D.; Roberts, Scott; Johnson, William L.

    2016-02-01

    With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals.

  9. PROCESS OF PRODUCING SHAPED PLUTONIUM

    DOEpatents

    Anicetti, R.J.

    1959-08-11

    A process is presented for producing and casting high purity plutonium metal in one step from plutonium tetrafluoride. The process comprises heating a mixture of the plutonium tetrafluoride with calcium while the mixture is in contact with and defined as to shape by a material obtained by firing a mixture consisting of calcium oxide and from 2 to 10% by its weight of calcium fluoride at from 1260 to 1370 deg C.

  10. Shape memory metals. Final report

    SciTech Connect

    Dworak, T.D.

    1993-09-01

    The ability to define a manufacturing process to form, heat-treat, and join parts made of nickel-titanium and/or copper-zinc-aluminum shape memory alloys was investigated. The specific emphasis was to define a process that would produce shape memory alloy parts in the configuration of helical coils emulating the appearance of compression springs. In addition, the mechanical strength of the finished parts along with the development of a electrical lead attachment method using shape memory alloy wire was investigated.

  11. Shape memory and pseudoelasticity in metal nanowires.

    PubMed

    Park, Harold S; Gall, Ken; Zimmerman, Jonathan A

    2005-12-16

    Structural reorientations in metallic fcc nanowires are controlled by a combination of size, thermal energy, and the type of defects formed during inelastic deformation. By utilizing atomistic simulations, we show that certain fcc nanowires can exhibit both shape memory and pseudoelastic behavior. We also show that the formation of defect-free twins, a process related to the material stacking fault energy, nanometer size scale, and surface stresses is the mechanism that controls the ability of fcc nanowires of different materials to show a reversible transition between two crystal orientations during loading and thus shape memory and pseudoelasticity. PMID:16384469

  12. Developmental Differences in Shape Processing

    ERIC Educational Resources Information Center

    Sera, Maria D.; Gordon Millett, Katherine

    2011-01-01

    Considerable evidence indicates that shape similarity plays a major role in object recognition, identification and categorization. However, little is known about shape processing and its development. Across four experiments, we addressed two related questions. First, what makes objects similar in shape? Second, how does the processing of shape…

  13. Microstructural Characterization of a Polycrystalline Nickel-Based Superalloy Processed via Tungsten-Intert-Gas-Shaped Metal Deposition

    NASA Astrophysics Data System (ADS)

    Clark, Daniel; Bache, Martin R.; Whittaker, Mark T.

    2010-12-01

    Recent trials have produced tungsten-inert-gas (TIG)-welded structures of a suitable scale to allow an evaluation of the technique as an economic and commercial process for the manufacture of complex aeroengine components. The employment of TIG welding is shown to have specific advantages over alternative techniques based on metal inert gas (MIG) systems. Investigations using the nickel-based superalloy 718 have shown that TIG induces a smaller weld pool with less compositional segregation. In addition, because the TIG process involves a pulsed power source, a faster cooling rate is achieved, although this rate, in turn, compromises the deposition rate. The microstructures produced by the two techniques differ significantly, with TIG showing an absence of the detrimental delta and Laves phases typically produced by extended periods at a high temperature using MIG. Instead, an anisotropic dendritic microstructure was evident with a preferred orientation relative to the axis of epitaxy. Niobium was segregated to the interdendritic regions. A fine-scale porosity was evident within the microstructure with a maximum diameter of approximately 5 μm. This porosity often was found in clusters and usually was associated with the interdendritic regions. Subsequent postdeposition heat treatment was shown to have no effect on preexisting porosity and to have a minimal effect on the microstructure.

  14. Shaping metal nanocrystals through epitaxial seeded growth

    SciTech Connect

    Habas, Susan E.; Lee, Hyunjoo; Radmilovic, Velimir; Somorjai,Gabor A.; Yang, Peidong

    2008-02-17

    Morphological control of nanocrystals has becomeincreasingly important, as many of their physical and chemical propertiesare highly shape-dependent. Nanocrystal shape control for both single andmultiple material systems, however, remains fairly empirical andchallenging. New methods need to be explored for the rational syntheticdesign of heterostructures with controlled morphology. Overgrowth of adifferent material on well-faceted seeds, for example, allows for the useof the defined seed morphology to control nucleation and growth of thesecondary structure. Here, we have used highly faceted cubic Pt seeds todirect the epitaxial overgrowth of a secondary metal. We demonstrate thisconcept with lattice matched Pd to produce conformal shape-controlledcore-shell particles, and then extend it to lattice mismatched Au to giveanisotropic growth. Seeding with faceted nanocrystals may havesignificant potential towards the development of shape-controlledheterostructures with defined interfaces.

  15. Mechanochemical processing for metals and metal alloys

    DOEpatents

    Froes, Francis H.; Eranezhuth, Baburaj G.; Prisbrey, Keith

    2001-01-01

    A set of processes for preparing metal powders, including metal alloy powders, by ambient temperature reduction of a reducible metal compound by a reactive metal or metal hydride through mechanochemical processing. The reduction process includes milling reactants to induce and complete the reduction reaction. The preferred reducing agents include magnesium and calcium hydride powders. A process of pre-milling magnesium as a reducing agent to increase the activity of the magnesium has been established as one part of the invention.

  16. Near Net Shape production of metal components using LENS

    SciTech Connect

    Schlienger, E.; Dimos, D.; Griffith, M.; Michael, J.; Oliver, M.; Romero, T.; Smugeresky, J.

    1998-03-01

    Rapid Prototyping and Near Net Shape manufacturing technologies are the subject of considerable attention and development efforts. At Sandia National Laboratories, one such effort is LENS (Laser Engineered Net Shaping). The LENS process utilizes a stream of powder and a focused Nd YAG laser to build near net shape fully dense metal parts. In this process, a 3-D solid model is sliced, then an X-Y table is rastered under the beam to build each slice. The laser 1 powder head is incremented upward with each slice and the deposition process is controlled via shuttering of the laser. At present, this process is capable of producing fully dense metal parts of iron, nickel and titanium alloys including tool steels and aluminides. Tungsten components have also been produced. A unique aspect of this process is the ability to produce components wherein the composition varies at differing locations in the part. Such compositional variations may be accomplished in either a stepped or graded fashion. In this paper, the details of the process will be described. The deposition mechanism will be characterized and microstructures and their associated properties will be discussed. Examples of parts which have been produced will be shown and issues regarding dimensional control and surface finish will be addressed.

  17. Shaping of Metal-Organic Frameworks: From Fluid to Shaped Bodies and Robust Foams.

    PubMed

    Chen, Yifa; Huang, Xianqiang; Zhang, Shenghan; Li, Siqing; Cao, Sijia; Pei, Xiaokun; Zhou, Junwen; Feng, Xiao; Wang, Bo

    2016-08-31

    The applications of metal-organic frameworks (MOFs) toward industrial separation, catalysis, sensing, and some sophisticated devices are drastically affected by their intrinsic fragility and poor processability. Unlike organic polymers, MOF crystals are insoluble in any solvents and are usually not thermoplastic, which means traditional solvent- or melting-based processing techniques are not applicable for MOFs. Herein, a continuous phase transformation processing strategy is proposed for fabricating and shaping MOFs into processable fluids, shaped bodies, and even MOF foams that are capable of reversible transformation among these states. Based on this strategy, a cup-shaped Cu-MOF composite and hierarchically porous MOF foam were developed for highly efficient catalytic C-H oxidation (conv. 76% and sele. 93% for cup-shaped Cu-MOF composite and conv. 92% and sele. 97% for porous foam) with ease of recycling and dramatically improved kinetics. Furthermore, various MOF-based foams with low densities (<0.1 g cm(-3)) and high MOF loadings (up to 80 wt %) were obtained via this protocol. Imparted with hierarchically porous structures and fully accessible MOFs uniformly distributed, these foams presented low energy penalty (pressure drop <20 Pa, at 500 mL min(-1)) and showed potential applications as efficient membrane reactors. PMID:27511140

  18. Development of metallization process

    NASA Astrophysics Data System (ADS)

    Garcia, A., III

    1983-04-01

    Solar cells were produced using a Mo/Sn/TiH screen printed paste with a lead/borosilicate frit that are electrically comparable to control silver cells. The process is currently unsuccessful because the soldering of interconnects to these cells has proved difficult. Future work will investigate using CO instead of H2 as the reducing gas and putting an ITO coating on the cell prior to metallization.

  19. T-Shaped Emitter Metal Structures for HBTs

    NASA Technical Reports Server (NTRS)

    Fung, King Man; Samoska, Lorene; Velebir, James; Muller, Richard; Echternach, Pierre; Siegel, Peter; Smith, Peter; Martin, Suzanne; Malik, Roger; Rodwell, Mark; Urteaga, Miguel; Paidi, Vamsi; Griffith, Zack

    2006-01-01

    Metal emitter structures in a class of developmental InP-based high-speed heterojunction bipolar transistors (HBTs) have been redesigned to have T-shaped cross sections. T-cross-section metal features have been widely used in Schottky diodes and high-electron-mobility transistors, but not in HBTs. As explained, the purpose served by the present T cross-sectional shapes is to increase fabrication yields beyond those achievable with the prior cross-sectional shapes.

  20. Integrated decontamination process for metals

    DOEpatents

    Snyder, Thomas S.; Whitlow, Graham A.

    1991-01-01

    An integrated process for decontamination of metals, particularly metals that are used in the nuclear energy industry contaminated with radioactive material. The process combines the processes of electrorefining and melt refining to purify metals that can be decontaminated using either electrorefining or melt refining processes.

  1. Shaping Education Policy: Power and Process

    ERIC Educational Resources Information Center

    Mitchell, Douglas E., Ed.; Crowson, Robert L., Ed.; Shipps, Dorothy, Ed.

    2011-01-01

    "Shaping Education Policy" is a comprehensive overview of education politics and policy during the most turbulent and rapidly changing period in American history. Respected scholars review the history of education policy to explain the political powers and processes that shape education today. Chapters cover major themes that have influenced…

  2. Graspable Objects Shape Number Processing

    PubMed Central

    Ranzini, Mariagrazia; Lugli, Luisa; Anelli, Filomena; Carbone, Rossella; Nicoletti, Roberto; Borghi, Anna M.

    2011-01-01

    The field of numerical cognition represents an interesting case for action-based theories of cognition, since number is a special kind of abstract concept. Several studies have shown that within the parietal lobes adjacent neural regions code numerical magnitude and grasping-related information. This anatomical proximity between brain areas involved in number and sensorimotor processes may account for interactions between numerical magnitude and action. In particular, recent studies have demonstrated a causal role of action perception on numerical magnitude processing. If objects are represented in terms of actions (affordances), the causal role of action on number processing should extend to the case of objects affordances. This study investigates the relationship between numbers and objects affordances in two experiments, without (Experiment 1) or with (Experiment 2) the requirement of an action (i.e., participants were asked to hold an object in their hands during the task). The task consisted in repeating aloud the odd or even digit within a pair depending on the type of the preceding or following object. Order of presentation (object–number vs. number–object), Object type (graspable vs. ungraspable), Object size (small vs. large), and Numerical magnitude (small vs. large) were manipulated for each experiment. Experiment 1 showed a facilitation – in terms of quicker responses – for graspable over ungraspable objects preceded by numbers, and an effect of numerical magnitude after the presentation of graspable objects. Experiment 2 demonstrated that the action execution enhanced overall the sensitivity to numerical magnitude, and that at the same time it interfered with the effects of objects affordances on number processing. Overall, these findings demonstrate that numbers and graspable objects are strongly interrelated, supporting the view that abstract concepts may be grounded in the motor experience. PMID:22164141

  3. Shape-Controlled Metal-Metal and Metal-Polymer Janus Structures by Thermoplastic Embossing.

    PubMed

    Hasan, Molla; Kahler, Niloofar; Kumar, Golden

    2016-05-01

    We report the fabrication of metal-metal and metal-polymer Janus structures by embossing of thermoplastic metallic glasses and polymers. Hybrid structures with controllable shapes and interfaces are synthesized by template-assisted embossing. Different manufacturing strategies such as co-embossing and additive embossing are demonstrated for joining the materials with diverse compositions and functionalities. Structures with distinct combinations of properties such as hydrophobic-hydrophilic, opaque-transparent, insulator-conductor, and nonmagnetic-ferromagnetic are produced using this approach. These anisotropic properties are further utilized for selective functionalization of Janus structures.

  4. Metallic glass nanostructures of tunable shape and composition

    PubMed Central

    Liu, Yanhui; Liu, Jingbei; Sohn, Sungwoo; Li, Yanglin; Cha, Judy J.; Schroers, Jan

    2015-01-01

    Metals of hybrid nano-/microstructures are of broad technological and fundamental interests. Manipulation of shape and composition on the nanoscale, however, is challenging, especially for multicomponent alloys such as metallic glasses. Although top–down approaches have demonstrated nanomoulding, they are limited to very few alloy systems. Here we report a facile method to synthesize metallic glass nanoarchitectures that can be applied to a broad range of glass-forming alloys. This strategy, using multitarget carousel oblique angle deposition, offers the opportunity to achieve control over size, shape and composition of complex alloys at the nanoscale. As a consequence, nanostructures of programmable three-dimensional shapes and tunable compositions are realized on wafer scale for metallic glasses including the marginal glass formers. Realizing nanostructures in a wide compositional range allows chemistry optimization for technological usage of metallic glass nanostructures, and also enables the fundamental study on size, composition and fabrication dependences of metallic glass properties. PMID:25901951

  5. Shape memory in nanostructured metallic alloys

    NASA Astrophysics Data System (ADS)

    Guda Vishnu, Karthik

    Materials with nanoscale dimensions show mechanical and structural properties different to those at the macro scale and engineering their nanostructure opens up potential avenues for designing materials tailored for a specific application. This work is focused on shape memory materials, an important class of active materials with wide variety of applications in medical, aerospace and automobile industries, due to their two important properties of super-elasticity and shape memory. These unique properties originate from a solid-solid transformation called martensite transformation and the main objectives of this research are to i) study the atomic mechanisms of the martensite transformation, ii) study the effect of nano-structure on shape memory behavior and iii) computationally explore avenues through which their performance is optimized. A combination of density functional theory (DFT) and molecular dynamics (MD) simulations is used to achieve this. This approach gives an atomic level description and the effects of size, surfaces and interfaces are explicitly described. Detailed analysis of the atomic mechanisms of the martensite transformation in NiTi using DFT revealed a new phase transformation (B19'-B19'') that sheds light on why the theoretically predicted ground state (BCO) is not observed experimentally and that the experimentally observed martensite phase (B19') can be stabilized by internal stresses. This finding is very important as the theoretically predicted ground state does not allow for shape memory in nanoscale NiTi samples. The size effects caused by the presence of free surfaces and the role of nanostructure in martensite transformation have been investigated in thin NiTi slabs. Surface energies of B2 phase (austenite), B19 (orthorhombic), B19' (martensite) and the body centered orthorhombic phase (BCO) are calculated using DFT. (110)B2 surfaces with in-plane atomic displacements stabilize the austenite phase with respect to B19' and BCO, thus

  6. Shape-Controlled Metal Nanocrystals for Heterogeneous Catalysis.

    PubMed

    Ruditskiy, Aleksey; Peng, Hsin-Chieh; Xia, Younan

    2016-06-01

    The ability to control the shape of metal nanocrystals allows us to not only maneuver their physicochemical properties but also optimize their activity in a variety of applications. Heterogeneous catalysis, in particular, would benefit tremendously from the availability of metal nanocrystals with controlled shapes and well-defined facets or surface structures. The immediate benefits may include significant enhancements in catalytic activity and/or selectivity along with reductions in the materials cost. We provide a brief account of recent progress in the development of metal nanocrystals with controlled shapes and thereby enhanced catalytic performance for several reactions, including formic acid oxidation, oxygen reduction, and hydrogenation. In addition to monometallic nanocrystals, we also cover a bimetallic system, in which the two metals are formulated as alloyed, core-shell, or core-frame structures. We hope this article will provide further impetus for the development of next-generation heterogeneous catalysts essential to a broad range of applications. PMID:27023659

  7. Development of metallization process

    NASA Technical Reports Server (NTRS)

    Garcia, A., III

    1984-01-01

    Pastes are evaluated that contain additives to aid in the silicon to metallization contact. None are completely successful. Pastes are evaluated using a heated stage scanning electron microscope (SEM). This equipment shows promise for future evaluations.

  8. Shape Evolution of Metal Nanoparticles in Water Vapor Environment.

    PubMed

    Zhu, Beien; Xu, Zhen; Wang, Chunlei; Gao, Yi

    2016-04-13

    The structures of the metal nanoparticles are crucial for their catalytic activities. How to understand and even control the shape evolution of nanoparticles under reaction condition is a big challenge in heterogeneous catalysis. It has been proved that many reactive gases hold the capability of changing the structures and properties of metal nanoparticles. One interesting question is whether water vapor, such a ubiquitous environment, could induce the shape evolution of metal nanoparticles. So far this question has not received enough attention yet. In this work, we developed a model based on the density functional theory, the Wulff construction, and the Langmuir adsorption isotherm to explore the shape of metal nanoparticle at given temperature and water vapor pressure. By this model, we show clearly that water vapor could notably increase the fraction of (110) facets and decrease that of (111) facets for 3-8 nm Cu nanoparticles, which is perfectly consistent with the experimental observations. Further investigations indicate the water vapor has different effects on the different metal species (Cu, Au, Pt, and Pd). This work not only helps to understand the water vapor effect on the structures of metal nanoparticles but also proposes a simple but effective model to predict the shape of nanoparticles in certain environment.

  9. Hydrothermal alkali metal recovery process

    DOEpatents

    Wolfs, Denise Y.; Clavenna, Le Roy R.; Eakman, James M.; Kalina, Theodore

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by treating them with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of an added base to establish a pH during the treatment step that is higher than would otherwise be possible without the addition of the base. During the treating process the relatively high pH facilitates the conversion of water-insoluble alkali metal compounds in the alkali metal residues into water-soluble alkali metal constituents. The resultant aqueous solution containing water-soluble alkali metal constituents is then separated from the residue solids, which consist of the treated particles and any insoluble materials formed during the treatment step, and recycled to the gasification process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. Preferably, the base that is added during the treatment step is an alkali metal hydroxide obtained by water washing the residue solids produced during the treatment step.

  10. Metallic parts fabrication using the SIS process

    NASA Astrophysics Data System (ADS)

    Mojdeh, Mehdi

    Since early 1980s, quite a few techniques of Rapid Prototyping (RP), also known as Layered Manufacturing, have been developed. By building three-dimensional parts in a layer-by-layer additive manner, these techniques allow freeform fabrication of parts of complex geometry. Despite recent advances in fabrication of polymer parts, most of the existing rapid prototyping processes are still not capable of fabrication of accurate metallic parts with acceptable mechanical properties. Insufficient dimensional accuracy, limited number of materials, proper mechanical properties, required post machining and lack of repeatability between builds have greatly limited the market penetration of these techniques. This dissertation presents an innovative layered manufacturing technique for fabrication of dense metallic parts called Selective Inhibition Sintering (SIS), developed at the University of Southern California. The SIS-Metal technology adapts RP capabilities and extends them to the field of fabrication of metallic parts for a variety of applications such as tooling and low volume production. Using this process, a metallic part, with varying 3 dimensional geometries, can be automatically constructed from a wide range of materials. SIS-Metal is the only RP process which is suitable for fabrication of dense, complex shaped, accurate objects using a variety of materials. In the SIS-Metal process a metallic part is built layer by layer by deposition for each layer of an inhibitor material which defines the corresponding layer boundary and then filling the voids of the created geometry with metal powder; and compacting the layer formed to reach a high powder density. The resulting green part is then sintered in a furnace to yield the final functional part. In this research different inhibition techniques were explored and a series of single and multi layer parts was fabricated using the most promising inhibition technique, namely, macro-mechanical inhibition. Dimensional

  11. Comments on comet shapes and aggregation processes

    NASA Technical Reports Server (NTRS)

    Hartmann, William K.

    1989-01-01

    An important question for a comet mission is whether comet nuclei preserve information clarifying aggregation processes of planetary matter. New observational evidence shows that Trojan asteroids, as a group, display a higher fraction of highly-elongated objects than the belt. More recently evidence has accumulated that comet nuclei, as a group, also display highly-elongated shapes at macro-scale. This evidence comes from the several comets whose nuclear lightcurves or shapes have been well studied. Trojans and comet nuclei share other properties. Both groups have extremely low albedos and reddish-to neutral-black colors typical of asteroids of spectral class D, P, and C. Both groups may have had relatively low collision frequencies. An important problem to resolve with spacecraft imaging is whether these elongated shapes are primordial, or due to evolution of the objects. Two hypotheses that might be tested by a combination of global-scale and close-up imaging from various directions are: (1) The irregular shapes are primordial and related to the fact that these bodies have had lower collision frequencies than belt asteroids; or (2) The irregular shapes may be due to volatile loss.

  12. Metal nanoparticle catalysts beginning to shape-up.

    PubMed

    Roldan Cuenya, Beatriz

    2013-08-20

    The field of heterogeneous catalysis has received a remarkable amount of interest from scientific and industrial perspectives because of its enormous impact on the world's economy: more than 90% of chemical manufacturing processes use catalysts. Catalysts are also essential in converting hazardous waste into less harmful products (car exhaust) and in generating power (fuel cells). Yet in all applications, it remains a challenge to design long lasting, highly active, selective, and environmentally friendly catalytic materials and processes, ideally based on Earth-abundant elements. In addition, the field needs more satisfactory experimental and theoretical approaches to minimize trial and error experiments in catalyst development. Nanocatalysis is one area that is developing rapidly. Researchers have reported striking novel catalytic properties, including greatly enhanced reactivities and selectivities, for nanocatalysts compared to their bulk counterparts. Fully harnessing the power of nanocatalysts requires detailed understanding of the origin of their enhanced performance at the atomic level, which in turn requires fundamental knowledge of the geometric and electronic structures of these complex systems. Numerous studies report on the properties that affect the catalytic performance of metal naoparticles (NPs) such as their size, interaction with their support, and their oxidation state. Much less research elucidates the role played by the NP shape. Complicating the analysis is that the preceding parameters are not independent, since NP size and support will affect which NP shapes are most stable. In addition, we must consider the dynamic nature of NP catalysts and their response to the environment, since the working state of a NP catalyst might not be the state in which the catalyst was prepared, but rather a structural and/or chemical isomer that responded to the particular reaction conditions. In order to address the complexity of real-world catalysts

  13. PROCESS OF RECOVERING ALKALI METALS

    DOEpatents

    Wolkoff, J.

    1961-08-15

    A process is described of recovering alkali metal vapor by sorption on activated alumina, activated carbon, dehydrated zeolite, activated magnesia, or Fuller's earth preheated above the vaporization temperature of the alkali metal and subsequent desorption by heating the solvent under vacuum. (AEC)

  14. Reconfigurable liquid metal circuits by Laplace pressure shaping

    NASA Astrophysics Data System (ADS)

    Cumby, Brad L.; Hayes, Gerard J.; Dickey, Michael D.; Justice, Ryan S.; Tabor, Christopher E.; Heikenfeld, Jason C.

    2012-10-01

    We report reconfigurable circuits formed by liquid metal shaping with <10 pounds per square inch (psi) Laplace and vacuum pressures. Laplace pressure drives liquid metals into microreplicated trenches, and upon release of vacuum, the liquid metal dewets into droplets that are compacted to 10-100× less area than when in the channel. Experimental validation includes measurements of actuation speeds exceeding 30 cm/s, simple erasable resistive networks, and switchable 4.5 GHz antennas. Such capability may be of value for next generation of simple electronic switches, tunable antennas, adaptive reflectors, and switchable metamaterials.

  15. Processes for metal extraction

    NASA Technical Reports Server (NTRS)

    Bowersox, David F.

    1992-01-01

    This report describes the processing of plutonium at Los Alamos National Laboratory (LANL), and operation illustrating concepts that may be applicable to the processing of lunar materials. The toxic nature of plutonium requires a highly closed system for processing lunar surface materials.

  16. Semisolid Metal Processing Consortium

    SciTech Connect

    Apelian,Diran

    2002-01-10

    Mathematical modeling and simulations of semisolid filling processes remains a critical issue in understanding and optimizing the process. Semisolid slurries are non-Newtonian materials that exhibit complex rheological behavior. There the way these slurries flow in cavities is very different from the way liquid in classical casting fills cavities. Actually filling in semisolid processing is often counter intuitive

  17. METAL EXTRACTION PROCESS

    DOEpatents

    Lewis, G.W. Jr.; Rhodes, D.E.

    1957-11-01

    An improved method for extracting uranium from aqueous solutions by solvent extraction is presented. A difficulty encountered in solvent extraction operations using an organic extractant (e.g., tributyl phosphate dissolved in kerosene or carbon tetrachloride) is that emulsions sometimes form, and phase separation is difficult or impossible. This difficulty is overcome by dissolving the organic extractant in a molten wax which is a solid at operating temperatures. After cooling, the wax which now contains the extractant, is broken into small particles (preferably flakes) and this wax complex'' is used to contact the uranium bearing solutions and extract the metal therefrom. Microcrystalline petroleum wax and certain ethylene polymers have been found suitable for this purpose.

  18. METAL PLATING PROCESS

    DOEpatents

    Walker, D.E.; Noland, R.A.

    1958-08-12

    A process ts described for obtaining a closely bonded coating of steel or iron on uranium. The process consists of providing, between the steel and uramium. a layer of silver. amd then pressure rolling tbe assembly at about 600 deg C until a reduction of from l0 to 50% has been obtained.

  19. METAL RECOVERY PROCESS

    DOEpatents

    Werner, L.B.; Hill, O.F.

    1957-12-01

    A process is presented for the separation of plutonium from the niobium oxide which is frequently used as a carrier precipitate to separate the plutonium from solutions of dissolved fuel elements. The niobium oxide, plutonium bearing precipitate is treated with hydrogen fluoride converting the niobium to the volatile pentafluoride, while the plutonium is changed into the substantially non- volatile plutonium tetrafluoride. After the niobium has been removed, the plutonium tetrafluoride is reacted with elemental fluorine, converting it to a higher plutonium fluoride and this may in turn be volitilized away from any residual impurities.

  20. The frequency selectivity of double H-shaped metallic structures

    NASA Astrophysics Data System (ADS)

    Bu, Xiaoxia; Zhao, Guozhong

    2013-12-01

    This paper presents the design and numerical simulation of the double H-shaped metallic periodic structure based on finite difference time domain (FDTD) method in terahertz frequency range. The double H-shaped structure unit cell consists of two H structures overlapped in the same plane. Numerical simulation results show that the double H-shaped structure results in a distinct and strong transmission trap in 0.2~3.0THz range. The position and the full wave at half maximum (FWHM) of transmission trap are changed with different structure size. The surface current distribution of structure is numerical simulated, which clarifies the frequency selection mechanism of the transmission spectra.

  1. Extraction process for removing metallic impurities from alkalide metals

    SciTech Connect

    Royer, Lamar T.

    1988-01-01

    A development is described for removing metallic impurities from alkali metals by employing an extraction process wherein the metallic impurities are extracted from a molten alkali metal into molten lithium metal due to the immiscibility of the alkali metals in lithium and the miscibility of the metallic contaminants or impurities in the lithium. The purified alkali metal may be readily separated from the contaminant-containing lithium metal by simple decanting due to the differences in densities and melting temperatures of the alkali metals as compared to lithium.

  2. Extraction process for removing metallic impurities from alkalide metals

    SciTech Connect

    Royer, L.T.

    1987-03-20

    A development is described for removing metallic impurities from alkali metals by employing an extraction process wherein the metallic impurities are extracted from a molten alkali metal into molten lithium metal due to the immiscibility of the alkali metals in lithium and the miscibility of the metallic contaminants or impurities in the lithium. The purified alkali metal may be readily separated from the contaminant-containing lithium metal by simple decanting due to the differences in densities and melting temperatures of the alkali metals as compared to lithium.

  3. Process for Producing Metal Compounds From Graphite Oxide

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh (Inventor)

    2000-01-01

    A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen. This intermediary product can be fiber processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon. metal carbonate. and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

  4. Process for producing metal compounds from graphite oxide

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh (Inventor)

    2000-01-01

    A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

  5. Process for Producing Metal Compounds from Graphite Oxide

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh (Inventor)

    2000-01-01

    A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon. metal. chloride. and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon. metal carbonate. and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide: b) in an inert environment to produce metal oxide on carbon substrate: c) in a reducing environment. to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

  6. Temporal pulse shaping for smoothing of printed metal surfaces

    NASA Astrophysics Data System (ADS)

    Berg, Yuval; Zenou, Michael; Dolev, Omer; Kotler, Zvi

    2015-01-01

    The surfaces of laser-induced forward transfer (LIFT) printed metal structures show typical roughness characteristic of the metal droplet size (3 to 10 μm). Submicron voids are often observed in the bulk of such printed metal structures with consequences on the mechanical strength, chemical resistivity, and electrical conductivity. We present the results of our efforts to reduce surface roughness and bulk voids by controlled laser melting. We have used temporally shaped pulses from a fiber laser tunable in the range from 1 to 600 ns in order to improve the quality of LIFT printed copper and aluminum structures. For the best case shown, roughness was improved from RRMS=0.8 μm to RRMS=0.2 μm and the relative percentage of the voids was reduced from 7.3% to 0.9%.

  7. Near net shape processing for solar thermal propulsion hardware using directed light fabrication

    SciTech Connect

    Milewski, J.O.; Fonseca, J.C.; Lewis, G.K.

    1998-12-01

    Directed light fabrication (DLF) is a direct metal deposition process that fuses gas delivered powder, in the focal zone of a high powered laser beam to form fully fused near net shaped components. The near net shape processing of rhenium, tungsten, iridium and other high temperature materials may offer significant cost savings compared with conventional processing. This paper describes a 3D parametric solid model, integrated with a manufacturing model, and creating a control field which runs on the DLF machine directly depositing a fully dense, solid metal, near net shaped, nozzle component. Examples of DLF deposited rhenium, iridium and tantalum, from previous work, show a continuously solidified microstructure in rod and tube shapes. Entrapped porosity indicates the required direction for continued process development. These combined results demonstrate the potential for a new method to fabricate complex near net shaped components using materials of interest to the space and aerospace industries.

  8. Application of nondiffracting Bessel beams for shaping of surface metal microstructures

    NASA Astrophysics Data System (ADS)

    Drampyan, Rafael; Leonov, Nikita; Vartanyan, Tigran

    2016-08-01

    A novel method of laser-controlled shaping of metal microstructures based on the processes of metal atoms adsorption on the surface of crystalline substrate and simultaneous control of photostimulated desorption of atoms by spatially modulated nondiffracting laser beam illumination is presented. The experiments were performed for sodium atoms deposition to the sapphire substrate, which was illuminated by Bessel beam at 532 nm wavelength and 2 W/cm2 intensity. Experiments showed that the optical pattern was well reproduced in the sodium deposits thus creating the annularly microstructured metal film with few tens nanometre thickness.

  9. Laser Peening - A Processing Tool to Strengthen Metals or Alloys

    SciTech Connect

    Chen, H-L; Hackel, L A

    2003-09-01

    Laser peening is an emerging modern process that impresses a compressive stress into the surfaces of metals or alloys. This treatment can reduce the rate of fatigue cracking and stress corrosion cracking in structural metals or alloys needed for aerospace, nuclear power plants, and military applications. Laser peening could also be used to form metals or alloys into precise shapes without their yielding, leaving their surfaces in a crack resistant compressive state.

  10. Electromagnetic transmission of T-shape periodic metallic grating

    NASA Astrophysics Data System (ADS)

    Wang, Yanhua; Zhang, Yan

    2008-03-01

    Transmittance property of the metal film with periodic T-shape structure in the near infrared region has been investigated by using the two-dimensional Finite-Difference Time-Domain (FDTD) method. The T-shape means that the slits' width of the upper section is larger than the lower part in a cell. All slits are narrower than the illuminating wavelengths. The electromagnetic transmission peak waggles with wavelength increasing while augmenting the deepness of the upper section and fixing the total height of the grating film. The wider upper sub-wavelength slit displays larger waggle extent in the transmission spectrum. The sub-wavelength slits works as waveguide and effective indexes of the waveguide varied with the width of slits. The upper and lower sub-wavelength slits show different effective indexes due to they have different widths. Changing the deepness will adjust the length of the resonance cavity. The transmission spectrum waggles while deepening the upper slits, which is visible in Fabry-Perot resonance. The field distribution of the light with peak transmission in and near a cell of the grating testifies the Fabry-Perot effect. An analytical equation is also provided to approximately locate the transmission peaks. The T-shape structure in a cell of metal grating supplies a new way to modulate the transmission spectrum.

  11. Metal rolling - Asymmetrical rolling process

    NASA Astrophysics Data System (ADS)

    Alexa, V.; Raţiu, S.; Kiss, I.

    2016-02-01

    The development of theory and practice related to the asymmetric longitudinal rolling process is based on the general theory of metalworking by pressure and symmetric rolling theory, to which a large number of scientists brought their contribution. The rolling of metal materials was a serious problem throughout history, either economically or technically, because the plating technologies enabled the consumption of raw materials (scarce and expensive) to be reduced, while improving the mechanical properties. Knowing the force parameters related to asymmetric rolling leads to the optimization of energy and raw material consumption. This paper presents data on symmetric rolling process, in order to comparatively highlight the particularities of the asymmetric process.

  12. Ultrafine Metal-Organic Right Square Prism Shaped Nanowires.

    PubMed

    Otake, Ken-Ichi; Otsubo, Kazuya; Sugimoto, Kunihisa; Fujiwara, Akihiko; Kitagawa, Hiroshi

    2016-05-23

    We report the structural design and control of electronic states of a new series of ultrafine metal-organic right square prism-shaped nanowires. These nanowires have a very small inner diameter of about 2.0 Å, which is larger than hydrogen and similar to xenon atomic diameters. The electronic states of nanowires can be widely controlled by substitution of structural components. Moreover, the platinum homometallic nanowire shows a 100 times higher proton conductivity than a palladium/platinum heterometallic one depending on the electronic states.

  13. Ultrafine Metal-Organic Right Square Prism Shaped Nanowires.

    PubMed

    Otake, Ken-Ichi; Otsubo, Kazuya; Sugimoto, Kunihisa; Fujiwara, Akihiko; Kitagawa, Hiroshi

    2016-05-23

    We report the structural design and control of electronic states of a new series of ultrafine metal-organic right square prism-shaped nanowires. These nanowires have a very small inner diameter of about 2.0 Å, which is larger than hydrogen and similar to xenon atomic diameters. The electronic states of nanowires can be widely controlled by substitution of structural components. Moreover, the platinum homometallic nanowire shows a 100 times higher proton conductivity than a palladium/platinum heterometallic one depending on the electronic states. PMID:27080935

  14. PROCESS FOR PREPARING URANIUM METAL

    DOEpatents

    Prescott, C.H. Jr.; Reynolds, F.L.

    1959-01-13

    A process is presented for producing oxygen-free uranium metal comprising contacting iodine vapor with crude uranium in a reaction zone maintained at 400 to 800 C to produce a vaporous mixture of UI/sub 4/ and iodine. Also disposed within the maction zone is a tungsten filament which is heated to about 1600 C. The UI/sub 4/, upon contacting the hot filament, is decomposed to molten uranium substantially free of oxygen.

  15. Laser induced forward transfer of metals by temporally shaped femtosecond laser pulses.

    PubMed

    Klini, A; Loukakos, P A; Gray, D; Manousaki, A; Fotakis, C

    2008-07-21

    Temporally shaped, femtosecond laser pulses have been used for controlling the size and the morphology of micron-sized metallic structures obtained by using the Laser Induced Forward Transfer (LIFT) technique. We report the effect of pulse shaping on the size and morphology of the deposited structures of Au, Zn, Cr on a function of the pulse separation time ??t (from 0 to 10 ps) of double pulses of variable intensities generated by using a liquid crystal spatial light modulator (SLM). The observed differences in size and morphology are correlated with the outcome of pump-probe experiments for the study of electron-phonon scattering dynamics and subsequent energy transfer processes to the bulk in the different metals employed. We propose that in metals with weak electron-lattice coupling, the electron ballistic motion and the resulting fast electron scattering at the film surface, as well as the internal electron thermalization process are crucial to the morphology and size of the transferred material. Therefore, temporal shaping within the corresponding time scales of these processes may be used for tailoring the features of the metallic structures obtained by LIFT.

  16. Surface shape resonances and surface plasmon polariton excitations in bottle-shaped metallic gratings

    NASA Astrophysics Data System (ADS)

    Skigin, Diana C.; Depine, Ricardo A.

    2001-04-01

    We study surface plasmon polariton excitations and surface shape resonances in a lossy metallic grating with bivalued cavities. The modal formalism is used to solve the diffraction problem for the infinite grating and the homogeneous problem for a single cavity in a plane surface. Both polarization modes are considered. We provide curves of reflected efficiency versus wavelength as well as near-field plots. The resonances are identified as dips in the reflected efficiency, which imply significant power absorptions. Results for various depths of the cavities and for several angles of incidence are shown, where the different types of resonant behavior can be appreciated. Particular attention is paid to the changes introduced by the finite conductivity of the metal in relation to the results obtained for a perfect conductor.

  17. Eros: Shape, topography, and slope processes

    USGS Publications Warehouse

    Thomas, P.C.; Joseph, J.; Carcich, B.; Veverka, J.; Clark, B.E.; Bell, J.F.; Byrd, A.W.; Chomko, R.; Robinson, M.; Murchie, S.; Prockter, L.; Cheng, A.; Izenberg, N.; Malin, M.; Chapman, C.; McFadden, L.A.; Kirk, R.; Gaffey, M.; Lucey, P.G.

    2002-01-01

    Stereogrammetric measurement of the shape of Eros using images obtained by NEAR's Multispectral Imager provides a survey of the major topographic features and slope processes on this asteroid. This curved asteroid has radii ranging from 3.1 to 17.7 km and a volume of 2535 ?? 20 km3. The center of figure is within 52 m of the center of mass provided by the Navigation team; this minimal difference suggests that there are only modest variations in density or porosity within the asteroid. Three large depressions 10, 8, and 5.3 km across represent different stages of degradation of large impact craters. Slopes on horizontal scales of ???300 m are nearly all less than 35??, although locally scarps are much steeper. The area distribution of slopes is similar to those on Ida, Phobos, and Deimos. Regions that have slopes greater than 25?? have distinct brighter markings and have fewer large ejecta blocks than do flatter areas. The albedo patterns that suggest downslope transport of regolith have sharper boundaries than those on Phobos, Deimos, and Gaspra. The morphology of the albedo patterns, their lack of discrete sources, and their concentration on steeper slopes suggest transport mechanisms different from those on the previously well-observed small bodies, perhaps due to a reduced relative effectiveness of impact gardening on Eros. Regolith is also transported in talus cones and in connected, sinuous paths extending as much as 2 km, with some evident as relatively darker material. Talus material in at least one area is a discrete superposed unit, a feature not resolved on other small bodies. Flat-floored craters that apparently contain ponded material also suggest discrete units that are not well mixed by impacts. ?? 2002 Elsevier Science (USA).

  18. Laser Engineered Net Shaping (LENS(TM)): A Tool for Direct Fabrication of Metal Parts

    SciTech Connect

    Atwood, C.; Ensz, M.; Greene, D.; Griffith, M.; Harwell, L.; Reckaway, D.; Romero, T.; Schlienger, E.; Smugeresky, J.

    1998-11-05

    For many years, Sandia National Laboratories has been involved in the development and application of rapid prototyping and dmect fabrication technologies to build prototype parts and patterns for investment casting. Sandia is currently developing a process called Laser Engineered Net Shaping (LENS~) to fabricate filly dense metal parts dwectly from computer-aided design (CAD) solid models. The process is similar to traditional laser-initiated rapid prototyping technologies such as stereolithography and selective laser sintering in that layer additive techniques are used to fabricate physical parts directly from CAD data. By using the coordinated delivery of metal particles into a focused laser beam apart is generated. The laser beam creates a molten pool of metal on a substrate into which powder is injected. Concurrently, the substrate on which the deposition is occurring is moved under the beam/powder interaction zone to fabricate the desired cross-sectiwal geometry. Consecutive layers are additively deposited, thereby producing a three-dmensional part. This process exhibits enormous potential to revolutionize the way in which metal parts, such as complex prototypes, tooling, and small-lot production parts, are produced. The result is a comple~ filly dense, near-net-shape part. Parts have been fabricated from 316 stainless steel, nickel-based alloys, H13 tool steel, and titanium. This talk will provide a general overview of the LENS~ process, discuss potential applications, and display as-processed examples of parts.

  19. A shape-based account for holistic face processing.

    PubMed

    Zhao, Mintao; Bülthoff, Heinrich H; Bülthoff, Isabelle

    2016-04-01

    Faces are processed holistically, so selective attention to 1 face part without any influence of the others often fails. In this study, 3 experiments investigated what type of facial information (shape or surface) underlies holistic face processing and whether generalization of holistic processing to nonexperienced faces requires extensive discrimination experience. Results show that facial shape information alone is sufficient to elicit the composite face effect (CFE), 1 of the most convincing demonstrations of holistic processing, whereas facial surface information is unnecessary (Experiment 1). The CFE is eliminated when faces differ only in surface but not shape information, suggesting that variation of facial shape information is necessary to observe holistic face processing (Experiment 2). Removing 3-dimensional (3D) facial shape information also eliminates the CFE, indicating the necessity of 3D shape information for holistic face processing (Experiment 3). Moreover, participants show similar holistic processing for faces with and without extensive discrimination experience (i.e., own- and other-race faces), suggesting that generalization of holistic processing to nonexperienced faces requires facial shape information, but does not necessarily require further individuation experience. These results provide compelling evidence that facial shape information underlies holistic face processing. This shape-based account not only offers a consistent explanation for previous studies of holistic face processing, but also suggests a new ground-in addition to expertise-for the generalization of holistic processing to different types of faces and to nonface objects.

  20. Fast Electronic Relaxation in Metal Clusters via Excitation of Coherent Shape Deformations: Slipping Through a Bottleneck

    NASA Astrophysics Data System (ADS)

    Kresin, Vitaly; Ovchinnikov, Yuri; Kresin, Vladimir

    2005-03-01

    We introduce and describe a fast electronic relaxation channel which is particular to free metallic nanoclusters. This channel overcomes the possibility of a phonon bottleneck by invoking the essential role of cluster shape deformations. Such a deformation entails the appearance of coherent surface phonon excitations and enables internal conversion at the level crossing point, thus allowing large energy transfer from an excited electron to the ionic subsystem. As a result, one can show that (unlike usual multiphonon processes) the shape deformation channel is capable of producing short electronic relaxation times, much less than a picosecond. The calculations are in agreement with recent pump-probe photoelectron measurements of relaxation in Aln^- clusters.

  1. Free form fabrication of metallic components using laser engineered net shaping (LENS{trademark})

    SciTech Connect

    Griffith, M.L.; Keicher, D.M.; Atwood, C.L.

    1996-09-01

    Solid free form fabrication is one of the fastest growing automated manufacturing technologies that has significantly impacted the length of time between initial concept and actual part fabrication. Starting with CAD renditions of new components, several techniques such as stereolithography and selective laser sintering are being used to fabricate highly accurate complex three-dimensional concept models using polymeric materials. Coupled with investment casting techniques, sacrificial polymeric objects are used to minimize costs and time to fabricate tooling used to make complex metal castings. This paper will describe recent developments in a new technology, known as LENS{sup {trademark}} (Laser Engineered Net Shaping), to fabricate metal components directly from CAD solid models and thus further reduce the lead times for metal part fabrication. In a manner analogous to stereolithography or selective sintering, the LENS{sup {trademark}} process builds metal parts line by line and layer by layer. Metal particles are injected into a laser beam, where they are melted and deposited onto a substrate as a miniature weld pool. The trace of the laser beam on the substrate is driven by the definition of CAD models until the desired net-shaped densified metal component is produced.

  2. Near-net-shape manufacturing: Spray-formed metal matrix composites and tooling

    NASA Technical Reports Server (NTRS)

    Mchugh, Kevin M.

    1994-01-01

    Spray forming is a materials processing technology in which a bulk liquid metal is converted to a spray of fine droplets and deposited onto a substrate or pattern to form a near-net-shape solid. The technology offers unique opportunities for simplifying materials processing without sacrificing, and oftentimes substantially improving, product quality. Spray forming can be performed with a wide range of metals and nonmetals, and offers property improvements resulting from rapid solidification (e.g. refined microstructures, extended solid solubilities and reduced segregation). Economic benefits result from process simplification and the elimination of unit operations. The Idaho National Engineering Laboratory is developing a unique spray-forming method, the Controlled Aspiration Process (CAP), to produce near-net-shape solids and coatings of metals, polymers, and composite materials. Results from two spray-accompanying technical and economic benefits. These programs involved spray forming aluminum strip reinforced with SiC particulate, and the production of tooling, such as injection molds and dies, using low-melting-point metals.

  3. Laser engineered net shaping (LENS) for the repair and modification of NWC metal components.

    SciTech Connect

    Atwood, Clinton J.; Smugeresky, John E. (Sandia National Labs, Livermore,CA); Gill, David Dennis

    2006-11-01

    Laser Engineered Net Shaping{trademark} (LENS{reg_sign}) is a layer additive manufacturing process that creates fully dense metal components using a laser, metal powder, and a computer solid model. This process has previously been utilized in research settings to create metal components and new material alloys. The ''Qualification of LENS for the Repair and Modification of Metal NWC Components'' project team has completed a Technology Investment project to investigate the use of LENS for repair of high rigor components. The team submitted components from four NWC sites for repair or modification using the LENS process. These components were then evaluated for their compatibility to high rigor weapons applications. The repairs included hole filling, replacement of weld lips, addition of step joints, and repair of surface flaws and gouges. The parts were evaluated for mechanical properties, corrosion resistance, weldability, and hydrogen compatibility. This document is a record of the LENS processing of each of these component types and includes process parameters, build strategies, and lessons learned. Through this project, the LENS process was shown to successfully repair or modify metal NWC components.

  4. Metal Matrix Composite LOX Turbopump Housing Via Novel Tool-Less Net-Shape Pressure Infiltration Casting Technology

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Lee, Jonathan; Bhat, Biliyar; Wells, Doug; Gregg, Wayne; Marsh, Matthew; Genge, Gary; Forbes, John; Salvi, Alex; Cornie, James A.; Jones, Clyde S. (Technical Monitor)

    2002-01-01

    This presentation provides an overview of the effort by Metal Matrix Cast Composites, Inc. to redesign turbopump housing joints using metal matrix composite material and a toolless net-shape pressure infiltration casting technology. Topics covered include: advantage of metal matrix composites for propulsion components, baseline pump design and analysis, advanced toolless pressure infiltration casting process, subscale pump housing, preform splicing and joining for large components, and fullscale pump housing redesign.

  5. PROCESS OF PRODUCING ACTINIDE METALS

    DOEpatents

    Magel, T.T.

    1959-07-14

    The preparation of actinide metals in workable, coherent form is described. In general, the objects of the invention are achieved by heating a mixture of an oxide and a halide of an actinide metal such as uranium with an alkali metal on alkaline earth metal reducing agent in the presence of iodine.

  6. Precision linear shaped charge analyses for severance of metals

    SciTech Connect

    Vigil, M.G.

    1996-08-01

    The Precision Linear Shaped Charge (PLSC) design concept involves the independent fabrication and assembly of the liner (wedge of PLSC), the tamper/confinement, and explosive. The liner is the most important part of a linear shaped charge (LSC) and should be fabricated by a more quality controlled, precise process than the tamper material. Also, this concept allows the liner material to be different from the tamper material. The explosive can be loaded between the liner and tamper as the last step in the assembly process rather than the first step as in conventional LSC designs. PLSC designs have been shown to produce increased jet penetrations in given targets, more reproducible jet penetration, and more efficient explosive cross-section geometries using a minimum amount of explosive. The Linear Explosive Shaped Charge Analysis (LESCA) code developed at Sandia National Laboratories has been used to assist in the design of PLSCs. LESCA predictions for PLSC jet tip velocities, jet-target impact angles, and jet penetration in aluminum and steel targets are compared to measured data. The advantages of PLSC over conventional LSC are presented. As an example problem, the LESCA code was used to analytically develop a conceptual design for a PLSC component to sever a three-inch thick 1018 steel plate at a water depth of 500 feet (15 atmospheres).

  7. Process for improving metal production in steelmaking processes

    DOEpatents

    Pal, Uday B.; Gazula, Gopala K. M.; Hasham, Ali

    1996-01-01

    A process and apparatus for improving metal production in ironmaking and steelmaking processes is disclosed. The use of an inert metallic conductor in the slag containing crucible and the addition of a transition metal oxide to the slag are the disclosed process improvements.

  8. Process for improving metal production in steelmaking processes

    DOEpatents

    Pal, U.B.; Gazula, G.K.M.; Hasham, A.

    1996-06-18

    A process and apparatus for improving metal production in ironmaking and steelmaking processes is disclosed. The use of an inert metallic conductor in the slag containing crucible and the addition of a transition metal oxide to the slag are the disclosed process improvements. 6 figs.

  9. Hydrothermal alkali metal catalyst recovery process

    DOEpatents

    Eakman, James M.; Clavenna, LeRoy R.

    1979-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles primarily in the form of water soluble alkali metal formates by treating the particles with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of added carbon monoxide. During the treating process the water insoluble alkali metal compounds comprising the insoluble alkali metal residues are converted into water soluble alkali metal formates. The resultant aqueous solution containing water soluble alkali metal formates is then separated from the treated particles and any insoluble materials formed during the treatment process, and recycled to the gasification process where the alkali metal formates serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. This process permits increased recovery of alkali metal constituents, thereby decreasing the overall cost of the gasification process by reducing the amount of makeup alkali metal compounds necessary.

  10. Development of techniques for processing metal-metal oxide systems

    NASA Technical Reports Server (NTRS)

    Johnson, P. C.

    1976-01-01

    Techniques for producing model metal-metal oxide systems for the purpose of evaluating the results of processing such systems in the low-gravity environment afforded by a drop tower facility are described. Because of the lack of success in producing suitable materials samples and techniques for processing in the 3.5 seconds available, the program was discontinued.

  11. Metals processing control by counting molten metal droplets

    DOEpatents

    Schlienger, Eric; Robertson, Joanna M.; Melgaard, David; Shelmidine, Gregory J.; Van Den Avyle, James A.

    2000-01-01

    Apparatus and method for controlling metals processing (e.g., ESR) by melting a metal ingot and counting molten metal droplets during melting. An approximate amount of metal in each droplet is determined, and a melt rate is computed therefrom. Impedance of the melting circuit is monitored, such as by calculating by root mean square a voltage and current of the circuit and dividing the calculated current into the calculated voltage. Analysis of the impedance signal is performed to look for a trace characteristic of formation of a molten metal droplet, such as by examining skew rate, curvature, or a higher moment.

  12. Lateralization of Object-Shape Information in Semantic Processing

    ERIC Educational Resources Information Center

    Zwaan, Rolf A.; Yaxley, Richard H.

    2004-01-01

    An experiment was conducted to examine whether perceptual information, specifically the shape of objects, is activated during semantic processing. Subjects judged whether a target word was related to a prime word. Prime-target pairs that were not associated, but whose referents had similar shapes (e.g. LADDER-RAILROAD) yielded longer ''no''…

  13. Process for making transition metal nitride whiskers

    DOEpatents

    Bamberger, C.E.

    1988-04-12

    A process for making metal nitrides, particularly titanium nitride whiskers, using a cyanide salt as a reducing agent for a metal compound in the presence of an alkali metal oxide. Sodium cyanide, various titanates and titanium oxide mixed with sodium oxide react to provide titanium nitride whiskers that can be used as reinforcement to ceramic composites. 1 fig., 1 tab.

  14. Process for making transition metal nitride whiskers

    DOEpatents

    Bamberger, Carlos E.

    1989-01-01

    A process for making metal nitrides, particularly titanium nitride whiskers, using a cyanide salt as a reducing agent for a metal compound in the presence of an alkali metal oxide. Sodium cyanide, various titanates and titanium oxide mixed with sodium oxide react to provide titanium nitride whiskers that can be used as reinforcement to ceramic composites.

  15. Synthesis and processing of composites by reactive metal penetration

    SciTech Connect

    Loehman, R.E.; Ewsuk, K.G.; Tomsia, A.P.

    1995-05-01

    Ceramic-metal composites are being developed because their high stiffness-to weight ratios, good fracture toughness, and variable electrical and thermal properties give them advantages over more conventional materials. However, because ceramic-metal composite components presently are more expensive than monolithic materials, improvements in processing are required to reduce manufacturing costs. Reactive metal penetration is a promising new method for making ceramic- and metal-matrix composites that has the advantage of being inherently a net-shape process. This technique, once fully developed, will provide another capability for manufacturing the advanced ceramic composites that are needed for many light-weight structural and wear applications. The lower densities of these composites lead directly to energy savings in use. Near-net-shape fabrication of composite parts should lead to additional savings because costly and energy intensive grinding and machining operations are significantly reduced, and the waste generated from such finishing operations is minimized. The goals of this research program are: (1) to identify feasible compositional systems for making composites by reactive metal penetration; (2) to understand the mechanism(s) of composite formation by reactive metal penetration; and (3) to learn how to control and optimize reactive metal penetration for economical production of composites and composite coatings.

  16. The eelectrochemical processing of refractory metals

    NASA Astrophysics Data System (ADS)

    Sadoway, Donald R.

    1991-07-01

    Electrochemical processing is used extensively in the primary extraction of metals (electrowinning), the purification and recycling of metals (electrorefining), and the formation of metal coatings (electroplating). With respect to the refractory metals, electrochemical processing is conducted almost exclusively in nonaqueous media, predominantly in molten salts. Electrolysis infused salts as well as other nonaqueous media has enormous potential for materials processing. First, because of the special attributes of nonaqueous electrolytes, electrochemical processing in these media has an important role to play in the generation of advanced materials—materials with specialized chemistries or tailored microstructures (electrosynthesis). Second,as environmental quality standards rise beyond the capabilities of classical metals extraction technologies to comply, electrochemical processing may prove to be the only acceptable route from ore to metal.

  17. Laser-assisted solar cell metallization processing

    NASA Technical Reports Server (NTRS)

    Dutta, S.

    1984-01-01

    Laser assisted processing techniques utilized to produce the fine line, thin metal grid structures that are required to fabricate high efficiency solar cells are investigated. The tasks comprising these investigations are summarized. Metal deposition experiments are carried out utilizing laser assisted pyrolysis of a variety of metal bearing polymer films and metalloorganic inks spun onto silicon substrates. Laser decomposition of spun on silver neodecanoate ink yields very promising results. Solar cell comb metallization patterns are written using this technique.

  18. Synthesis and processing of composites by reactive metal penetration

    SciTech Connect

    Loehman, R.E.; Ewsuk, K.G.; Tomsia, A.P.; Fahrenholtz, W.G.

    1996-07-01

    Ceramic-metal composites are being developed as engineering materials because of their high stiffness-to-weight ratios, good fracture toughness, and because their electrical and thermal properties can be varied through control of their compositions and microstructures. Wider use of ceramic-metal composites requires improvements in synthesis and processing so that high-performance parts can be produced more economically. Over the past three years reactive metal penetration has been shown to be a promising technique for making ceramic and metal-matrix composites to near-net-shape with control of both composition and microstructure. It appears that reactive metal penetration could be an economical process for manufacturing many of the advanced ceramic composites that are needed for light-weight structural and wear applications for transportation and energy conversion devices. Near-net-shape fabrication of parts has the additional advantage that costly and energy intensive grinding and machining operations are significantly reduced, and the waste generated from such finishing operations is minimized. The goals of this research and development program are: (1) to identify compositions favorable for making composites by reactive metal penetration; (2) to understand the mechanism(s) by which these composites are formed; and (3) to control and optimize the process so that composites and composite coatings can be made economically.

  19. Distinct processes shape flashbulb and event memories.

    PubMed

    Tinti, Carla; Schmidt, Susanna; Testa, Silvia; Levine, Linda J

    2014-05-01

    In the present study, we examined the relation between memory for a consequential and emotional event and memory for the circumstances in which people learned about that event, known as flashbulb memory. We hypothesized that these two types of memory have different determinants and that event memory is not necessarily a direct causal determinant of flashbulb memory. Italian citizens (N = 352) described their memories of Italy's victory in the 2006 Football World Cup Championship after a delay of 18 months. Structural equation modeling showed that flashbulb memory and event memory could be clearly differentiated and were determined by two separate pathways. In the first pathway, importance predicted emotional intensity, which, in turn, predicted the frequency of overt and covert rehearsal. Rehearsal was the only direct determinant of vivid and detailed flashbulb memories. In the second pathway, importance predicted rehearsal by media exposure, which enhanced the accuracy and certainty of event memory. Event memory was also enhanced by prior knowledge. These results have important implications for the debate concerning whether the formation of flashbulb memory and event memory involve different processes and for understanding how flashbulb memory can be simultaneously so vivid and so error-prone.

  20. A Shape-Based Account for Holistic Face Processing

    ERIC Educational Resources Information Center

    Zhao, Mintao; Bülthoff, Heinrich H.; Bülthoff, Isabelle

    2016-01-01

    Faces are processed holistically, so selective attention to 1 face part without any influence of the others often fails. In this study, 3 experiments investigated what type of facial information (shape or surface) underlies holistic face processing and whether generalization of holistic processing to nonexperienced faces requires extensive…

  1. Metal Oxide Nanoparticles: The Importance of Size, Shape, Chemical Composition, and Valence State in Determining Toxicity

    NASA Astrophysics Data System (ADS)

    Dunnick, Katherine

    Nanoparticles, which are defined as a structure with at least one dimension between 1 and 100 nm, have the potential to be used in a variety of consumer products due to their improved functionality compared to similar particles of larger size. Their small size is associated with increased strength, improved catalytic properties, and increased reactivity; however, their size is also associated with increased toxicity in vitro and in vivo. Numerous toxicological studies have been conducted to determine the properties of nanomaterials that increase their toxicity in order to manufacture new nanomaterials with decreased toxicity. Data indicates that size, shape, chemical composition, and valence state of nanomaterials can dramatically alter their toxicity profile. Therefore, the purpose of this dissertation was to determine how altering the shape, size, and chemical composition of various metal oxide nanoparticles would affect their toxicity. Metal oxides are used in variety of consumer products, from spray-sun screens, to food coloring agents; thus, understanding the toxicity of metal oxides and determining which aspects affect their toxicity may provide safe alternatives nanomaterials for continued use in manufacturing. Tungstate nanoparticles toxicity was assessed in an in vitro model using RAW 264.7 cells. The size, shape, and chemical composition of these nanomaterials were altered and the effect on reactive oxygen species and general cytotoxicity was determined using a variety of techniques. Results demonstrate that shape was important in reactive oxygen species production as wires were able to induce significant reactive oxygen species compared to spheres. Shape, size, and chemical composition did not have much effect on the overall toxicity of these nanoparticles in RAW 264.7 cells over a 72 hour time course, implicating that the base material of the nanoparticles was not toxic in these cells. To further assess how chemical composition can affect toxicity

  2. Variation of the shape and morphological properties of silica and metal oxide powders by electro homogeneous precipitation

    DOEpatents

    Harris, Michael T.; Basaran, Osman A.; Sisson, Warren G.; Brunson, Ronald R.

    1997-01-01

    The present invention provides a method for preparing irreversible linear aggregates (fibrils) of metal oxide powders by utilizing static or pulsed DC electrical fields across a relatively non-conducting liquid solvent in which organometal compounds or silicon alkoxides have been dissolved. The electric field is applied to the relatively non-conducting solution throughout the particle formation and growth process promoting the formation of either linear aggregates (fibrils) or spherical shaped particles as desired. Thus the present invention provides a physical method for altering the size, shape and porosity of precursor hydrous metal oxide or hydrous silicon oxide powders for the development of advanced ceramics with improved strength and insulating capacity.

  3. Metals Processing Laboratory User Center (MPLUS)

    SciTech Connect

    Mackiewicz-Ludtka, G.; Hayden, H.W.

    1997-04-01

    The Metals Processing Laboratory User (MPLUS) Center was officially designated as a DOE User Facility in February, 1996. It`s primary purpose is to assist researchers in key U.S. industries, universities, and federal laboratories in improving energy efficiency and enhancing U.S. competitiveness in the world market. The MPLUS Center provides users the unique opportunity to address technology-related issues to solve metals-processing problems from a fully integrated approach. DOE facilitates the process and catalyzes industrial interactions that enables technical synergy and financial leveraging to take place between the industrial sector identifying and prioritizing their technological needs, and MPLUS, which provides access to the technical expertise and specialized facilities to address these needs. MPLUS is designed to provide U.S. industries with access to the specialized technical expertise and equipment needed to solve metals-processing issues that limit the development and implementation of emerging metals-processing technologies. As originated, MPLUS includes the following four primary user centers: Metals Processing, Metals Joining, Metals Characterization, and Metals Process Modeling. These centers are devoted to assisting U.S. industries in adjusting to rapid changes in the marketplace and in improving products and processes. This approach optimizes the complementary strengths of industry and government. Tremendous industrial response, has resulted in MPLUS expanding to meet the ever-growing technical needs and requests initiated by U.S. industry.

  4. Process for making silver metal filaments

    SciTech Connect

    Bamberger, C.E.

    1998-04-01

    This invention relates to a process for making filaments of metal compounds and more particularly to a process for making silver metal filaments. The United States Government has rights to this invention pursuant to Contract No. DE-AC05-8421400 with Lockheed Martin Energy Systems, Inc. awarded by the US Department of Energy.

  5. Thermal softening of metallic shaped-charge jets formed by the collapse of shaped-charge liners in the presence of a magnetic field

    NASA Astrophysics Data System (ADS)

    Fedorov, S. V.

    2016-05-01

    This paper presents an analysis of the possibility of increasing the ultimate stretching and penetration capability of metallic shaped-charge jets in the presence of an axial magnetic field in the shaped-charge liner due to heating and thermal softening of the jet material as a result of a sharp increase in the magnetic-field induction in the jet formation region upon liner collapse. This process is studied by numerical simulation in a quasi-two-dimensional formulation taking into account the inertial stretching of the conductive rigid-plastic rod in the presence of a longitudinal magnetic field in it.

  6. METAL PARTITIONING IN COMBUSTION PROCESSES

    EPA Science Inventory

    This article summarizes ongoing research efforts at the National Risk Management Research Laboratory of the U.S. Environmental Protection Agency examining [high temperature] metal behavior within combustion environments. The partitioning of non-volatile (Cr and Ni), semi-volatil...

  7. Process Simulation of Gas Metal Arc Welding Software

    2005-09-06

    ARCWELDER is a Windows-based application that simulates gas metal arc welding (GMAW) of steel and aluminum. The software simulates the welding process in an accurate and efficient manner, provides menu items for process parameter selection, and includes a graphical user interface with the option to animate the process. The user enters the base and electrode material, open circuit voltage, wire diameter, wire feed speed, welding speed, and standoff distance. The program computes the size andmore » shape of a square-groove or V-groove weld in the flat position. The program also computes the current, arc voltage, arc length, electrode extension, transfer of droplets, heat input, filler metal deposition, base metal dilution, and centerline cooling rate, in English or SI units. The simulation may be used to select welding parameters that lead to desired operation conditions.« less

  8. Process Simulation of Gas Metal Arc Welding Software

    SciTech Connect

    Murray, Paul E.

    2005-09-06

    ARCWELDER is a Windows-based application that simulates gas metal arc welding (GMAW) of steel and aluminum. The software simulates the welding process in an accurate and efficient manner, provides menu items for process parameter selection, and includes a graphical user interface with the option to animate the process. The user enters the base and electrode material, open circuit voltage, wire diameter, wire feed speed, welding speed, and standoff distance. The program computes the size and shape of a square-groove or V-groove weld in the flat position. The program also computes the current, arc voltage, arc length, electrode extension, transfer of droplets, heat input, filler metal deposition, base metal dilution, and centerline cooling rate, in English or SI units. The simulation may be used to select welding parameters that lead to desired operation conditions.

  9. Solid State Pathways to Complex Shape Evolution and Tunable Porosity during Metallic Crystal Growth

    PubMed Central

    Valenzuela, Carlos Díaz; Carriedo, Gabino A.; Valenzuela, María L.; Zúñiga, Luis; O'Dwyer, Colm

    2013-01-01

    Growing complex metallic crystals, supported high index facet nanocrystal composites and tunable porosity metals, and exploiting factors that influence shape and morphology is crucial in many exciting developments in chemistry, catalysis, biotechnology and nanoscience. Assembly, organization and ordered crystallization of nanostructures into complex shapes requires understanding of the building blocks and their association, and this relationship can define the many physical properties of crystals and their assemblies. Understanding crystal evolution pathways is required for controlled deposition onto surfaces. Here, complex metallic crystals on the nano- and microscale, carbon supported nanoparticles, and spinodal porous noble metals with defined inter-feature distances in 3D, are accomplished in the solid-state for Au, Ag, Pd, and Re. Bottom-up growth and positioning is possible through competitive coarsening of mobile nanoparticles and their site-specific crystallization in a nucleation-dewetted matrix. Shape evolution, density and growth mechanism of complex metallic crystals and porous metals can be imaged during growth. PMID:24026532

  10. Solid state pathways to complex shape evolution and tunable porosity during metallic crystal growth.

    PubMed

    Valenzuela, Carlos Díaz; Carriedo, Gabino A; Valenzuela, María L; Zúñiga, Luis; O'Dwyer, Colm

    2013-01-01

    Growing complex metallic crystals, supported high index facet nanocrystal composites and tunable porosity metals, and exploiting factors that influence shape and morphology is crucial in many exciting developments in chemistry, catalysis, biotechnology and nanoscience. Assembly, organization and ordered crystallization of nanostructures into complex shapes requires understanding of the building blocks and their association, and this relationship can define the many physical properties of crystals and their assemblies. Understanding crystal evolution pathways is required for controlled deposition onto surfaces. Here, complex metallic crystals on the nano- and microscale, carbon supported nanoparticles, and spinodal porous noble metals with defined inter-feature distances in 3D, are accomplished in the solid-state for Au, Ag, Pd, and Re. Bottom-up growth and positioning is possible through competitive coarsening of mobile nanoparticles and their site-specific crystallization in a nucleation-dewetted matrix. Shape evolution, density and growth mechanism of complex metallic crystals and porous metals can be imaged during growth.

  11. ELECTROLYTIC PROCESS FOR PRODUCING METALS

    DOEpatents

    Kopelman, B.; Holden, R.B.

    1961-06-01

    A method is described for reducing beryllium halides to beryllium. The beryllfum halide fs placed in an eutectic mixture of alkali halides and alkaline earth halides. The constituents of this eutectic bath are so chosen that it has a melting point less than the boiling point of mercury, which acts as a cathode for the system. The beryllium metal is then deposited in the mercury upon electrolysis.

  12. Paths of progress in liquid metal processing

    NASA Astrophysics Data System (ADS)

    McLean, A.; Soda, H.; Sommerville, I. D.

    1995-04-01

    Industry has identified three major issues as being fundamental to future technological developments: process step elimination, product-process integration, and intelligent processing. This article reviews these concepts by discussing recent research at the University of Toronto on plasma processing, netshape casting, and diagnostic sensors for the evaluation of liquid metal quality.

  13. Laser processing of metal surfaces for increasing paint adhesion

    NASA Astrophysics Data System (ADS)

    Hirose, Tomiyasu; Ichihara, Hideki; Sugimoto, Kenji; Sasazawa, Kazuo; Shibasaki, Shouji

    2000-01-01

    Painted metal exteriors of buildings begin to degrade in about 10 years due to solar heat, UV rays, the sea salt adhesion, the acid rain etc. When degradation and exfoliation of the paint film occurs, rust appears in the metal and replacement or repainting becomes necessary. The adhesion of paints on metal is usually achieved by chemical adhesion or by increasing the surface area by blast processing. In this study, the possibility of improving paint adhesion by forming minute holes on the metal surface by laser irradiation was studied through modeling of the adhesion of the paint film and adaptability to deformation. The viscosity and painting method depend on the size and location of the oles. The presence of the holes makes it possible to form complicated shapes by pressing because the holes absorb some of the strain caused by pressing.

  14. Online processing of shape information for control of grasping.

    PubMed

    Chen, Zhongting; Saunders, Jeffrey A

    2015-11-01

    When picking up objects, we tend to grasp at contact points that minimize slippage and torsion, which depend on the particular shape. Normally, grasp points could be planned before initiating movement. We tested whether grasp points can be determined during online control. Subjects reached to grasp virtual planar objects with varied shapes. On some trials, the object was changed during movement, either rotated by 45° or replaced with a different object. In all conditions, grasp axes were well adapted to the target shape, passing near the center of mass with low force closure angles. On perturbed trials, corrective adjustments were detectable within 320 ms and were toward the same grasp axes observed on unperturbed trials. Perturbations had little effect on either kinematics or the optimality of final grasp points. Our results demonstrate that the visuomotor system is capable of online processing of shape information to determine appropriate contact points for grasping.

  15. LEACHING OF METALS FROM MINERAL PROCESSING WASTE

    EPA Science Inventory

    The purpose of this project is to test the leaching of Mineral processing Waste (MPW) contaminated with heavy metals using scientifically defendable leaching tests other than TCLP. Past experience and literature have shown that TCLP underestiates the levels of metals such as oxoa...

  16. LEACHING OF METALS FROM MINERAL PROCESSING WASTE

    EPA Science Inventory

    The purpose of this project is to test the leaching of Mineral Processing Waste (MPW) contaminated with heavy metals using scientifically defendable leaching tests other than TCLP. Past experience and literature have shown that TCLP underestimates the levels of metals such as oxo...

  17. METAL CAPTURE BY SORBENTS IN COMBUSTION PROCESSES

    EPA Science Inventory

    The article gives results of an investigation of the use of sorbents to control trace metal emissions from combustion processes and an exploration of the underlying mechanisms. mphasis was on mechanisms in which the metal vapor was reactively scavenged by simple commercial sorben...

  18. Process for electrolytically preparing uranium metal

    DOEpatents

    Haas, Paul A.

    1989-01-01

    A process for making uranium metal from uranium oxide by first fluorinating uranium oxide to form uranium tetrafluoride and next electrolytically reducing the uranium tetrafluoride with a carbon anode to form uranium metal and CF.sub.4. The CF.sub.4 is reused in the fluorination reaction rather than being disposed of as a hazardous waste.

  19. Process for electrolytically preparing uranium metal

    DOEpatents

    Haas, Paul A.

    1989-08-01

    A process for making uranium metal from uranium oxide by first fluorinating uranium oxide to form uranium tetrafluoride and next electrolytically reducing the uranium tetrafluoride with a carbon anode to form uranium metal and CF.sub.4. The CF.sub.4 is reused in the fluorination reaction rather than being disposed of as a hazardous waste.

  20. Laser-assisted solar cell metallization processing

    NASA Technical Reports Server (NTRS)

    Dutta, S.

    1984-01-01

    Laser-assisted processing techniques utilized to produce the fine line, thin metal grid structures that are required to fabricate high efficiency solar cells are examined. Two basic techniques for metal deposition are investigated; (1) photochemical decomposition of liquid or gas phase organometallic compounds utilizing either a focused, CW ultraviolet laser (System 1) or a mask and ultraviolet flood illumination, such as that provided by a repetitively pulsed, defocused excimer laser (System 2), for pattern definition, and (2) thermal deposition of metals from organometallic solutions or vapors utilizing a focused, CW laser beam as a local heat source to draw the metallization pattern.

  1. Catalytic extraction processing of contaminated scrap metal

    SciTech Connect

    Griffin, T.P.; Johnston, J.E.; Payea, B.M.; Zeitoon, B.M.

    1995-12-01

    Molten Metal Technology was awarded a contract to demonstrate the applicability of the Catalytic Extraction Process, a proprietary process that could be applied to US DOE`s inventory of low level mixed waste. This paper is a description of that technology, and included within this document are discussions of: (1) Program objectives, (2) Overall technology review, (3) Organic feed conversion to synthetic gas, (4) Metal, halogen, and transuranic recovery, (5) Demonstrations, (6) Design of the prototype facility, and (7) Results.

  2. The processing and evaluation of clad metals

    NASA Astrophysics Data System (ADS)

    Forster, James A.; Jha, Sunil; Amatruda, Andrew

    1993-06-01

    Clad metals are a specific form of composites in which the materials are arranged in a layered structure. Cold-roll bonding techniques are employed to produce more than 20,000 tonnes of clad metal laminates each year in the United States. This article is an introductory description of the processing steps in cold-roll bonding, the nature of the bond created in this process, and the methods used to evaluate the bond's strength.

  3. Nanoforging – Innovation in three-dimensional processing and shaping of nanoscaled structures

    PubMed Central

    Rösler, Joachim

    2014-01-01

    Summary Background: This paper describes the shaping of freestanding objects out of metallic structures in the nano- and submicron size. The technique used, called nanoforging, is very similar to the macroscopic forging process. Results: With spring actuated tools produced by focused ion beam milling, controlled forging is demonstrated. With only three steps, a conical bar stock is transformed to a flat- and semicircular bent bar stock. Conclusion: Compared with other forming techniques in the reduced scale, nanoforging represents a beneficial approach in forming freestanding metallic structures, due to its simplicity, and supplements other forming techniques. PMID:25161840

  4. Influences on particle shape in underwater pelletizing processes

    SciTech Connect

    Kast, O. E-mail: matthias.musialek@ikt.uni-stuttgart.de E-mail: christian.bonten@ikt.uni-stuttgart.de; Musialek, M. E-mail: matthias.musialek@ikt.uni-stuttgart.de E-mail: christian.bonten@ikt.uni-stuttgart.de; Geiger, K. E-mail: matthias.musialek@ikt.uni-stuttgart.de E-mail: christian.bonten@ikt.uni-stuttgart.de; Bonten, C. E-mail: matthias.musialek@ikt.uni-stuttgart.de E-mail: christian.bonten@ikt.uni-stuttgart.de

    2014-05-15

    Underwater pelletizing has gained high importance within the last years among the different pelletizing technologies, due to its advantages in terms of throughput, automation, pellet quality and applicability to a large variety of thermoplastics. The resulting shape and quality of pellets, however, differ widely, depending on material characteristics and effects not fully understood yet. In an experimental set-up, pellets of different volumes and shapes were produced and the medium pellet mass, the pellet surface and the bulk density were analyzed in order to identify the influence of material properties and process parameters. Additionally, the shaping kinetics at the die opening were watched with a specially developed camera system. It was found that rheological material properties correlate with process parameters and resulting particle form in a complex way. Higher cutting speeds were shown to have a deforming influence on the pellets, leading to less spherical s and lower bulk densities. More viscous materials, however, showed a better resistance against this. Generally, the viscous properties of polypropylene proofed to be dominant over the elastic ones in regard to their influence on pellet shape. It was also shown that the shapes filmed at the die opening and the actual form of the pellets after a cooling track do not always correlate, indicating a significant influence of thermodynamic properties during the cooling.

  5. Transformational Learning in Botswana: How Culture Shapes the Process

    ERIC Educational Resources Information Center

    Merriam, Sharan B.; Ntseane, Gabo

    2008-01-01

    Transformational learning as presented by Jack Mezirow has been critiqued for its Western, rational, and cognitive orientation. This qualitative study was conducted in the African nation of Botswana and examines how that culture shaped the process. In-depth interviews were held with 12 adults who acknowledged having an experience that had…

  6. Shape measurement of bubble in a liquid metal

    NASA Astrophysics Data System (ADS)

    Saito, Y.; Shen, X.; Mishima, K.; Matsubayashi, M.

    2009-06-01

    Dynamic behavior of a two-phase bubble, i.e. a steam bubble containing a droplet evaporating in the bubble, in the molten alloy was clearly visualized using high-frame-rate neutron radiography. In relation to some direct contact heat exchanger design with molten lead-bismuth (Pb-Bi), experiments have been done at JRR-3M of JAEA (Japan Atomic Energy Agency) with water droplets evaporating in a stable thermally stratified Newton's alloy pool. The instantaneous shape and size of the bubble has been iteratively estimated from the void fraction distributions and total void volume by assuming a symmetrical bubble shape.

  7. Catalyst regeneration process including metal contaminants removal

    DOEpatents

    Ganguli, Partha S.

    1984-01-01

    Spent catalysts removed from a catalytic hydrogenation process for hydrocarbon feedstocks, and containing undesired metals contaminants deposits, are regenerated. Following solvent washing to remove process oils, the catalyst is treated either with chemicals which form sulfate or oxysulfate compounds with the metals contaminants, or with acids which remove the metal contaminants, such as 5-50 W % sulfuric acid in aqueous solution and 0-10 W % ammonium ion solutions to substantially remove the metals deposits. The acid treating occurs within the temperature range of 60.degree.-250.degree. F. for 5-120 minutes at substantially atmospheric pressure. Carbon deposits are removed from the treated catalyst by carbon burnoff at 800.degree.-900.degree. F. temperature, using 1-6 V % oxygen in an inert gas mixture, after which the regenerated catalyst can be effectively reused in the catalytic process.

  8. Metals and Alloys Material Stabilization Process Plan

    SciTech Connect

    RISENMAY, H.R.; BURK, R.A.

    2000-05-18

    This Plan outlines the process for brushing metal and alloys in accordance with the path forward discussed in the Integrated Project Management Plan for the Plutonium Finishing Plant Stabilization and Deactivation Project, HNF-3617, and requirements set forth in the Project Management Plan for Materials Stabilization, HNF-3605. This plan provides the basis for selection of the location to process, the processes involved, equipment to be used, and the characterization of the contents of the can. The scope of the process is from retrieval of metals and alloys from storage to transfer back to storage in a repackaged configuration.

  9. Molten metal processes reap profit from waste

    SciTech Connect

    Mather, R.; Steckler, D.; Kimmel, S.; Tanner, A.

    1996-05-01

    Over the past few years, a new tool has been added to the waste-processing arsenal. The use of a reactor filled with molten metal has been proven for dissociating a wide range of organic, organometallic, metallic and inorganic wastes into their constituent elements. Such reactors allow users to manipulate the solution chemistry and operating conditions inside, to reconfigure the dissociated elements into useful products, such as synthesis gas (hydrogen and carbon monoxide), HCl, metal alloys and ceramics, while ensuring high levels of environmental performance. A commercial-scale, molten metal processing unit is being constructed at Hoechst Celanese Corp.`s Bay City, Tex., chemical manufacturing plant. The unit with an estimated capital cost of $25 million, will be constructed, owned and operated by Molten Metal Technology, Inc., and will use MMT`s Catalytic Extraction processing. Once online, the facility will process wastes from Hoechst Celanese`s Gulf Coast plants and from other nearby chemical manufacturers. In addition to processing wastes, the facility will generate a syngas product that will be used onsite as a raw material during chemical manufacturing. Presented are the results of commercial-scale demonstrations using a prototype molten metal reactor for a wide range of industrial waste streams.

  10. Synthesis and processing of composites by reactive metal penetration

    SciTech Connect

    Loehman, R.E.; Ewsuk, K.G.; Tomsia, A.P.

    1997-04-01

    Achieving better performance in commercial products and processes often is dependent on availability of new and improved materials. Ceramic-metal composites have advantages over more conventional materials because of their high stiffness-to-weight ratios, good fracture toughness, and because their electrical and thermal properties can be varied through control of their compositions and microstructures. However, ceramic composites will be more widely used only when their costs are competitive with other materials and when designers have more confidence in their reliability. Over the past four years reactive metal penetration has been shown to be a promising technique for making ceramic and metal-matrix composites to near-net-shape with control of both composition and microstructure. It appears that, with sufficient development, reactive metal penetration could be an economical process for manufacturing many of the advanced ceramic composites that are needed for light-weight structural and wear applications for transportation and energy conversion devices. Near-net-shape fabrication of parts is a significant advantage because costly and energy intensive grinding and machining operations are substantially reduced, and the waste generated from such finishing operations is minimized. The most promising compositions to date consist of Al and Al{sub 2}O{sub 3}; thus, these composites should be of particular interest to the aluminum industry. The goals of this ceramic-metal composite research and development program are: (1) to identify compositions favorable for making composites by reactive metal penetration; (2) to understand the mechanism(s) by which these composites are formed; (3) to control and optimize the process so that composites and composite coatings can be made economically; and (4) to apply R&D results to problems of interest to the aluminum industry.

  11. Process for bonding elastomers to metals

    NASA Technical Reports Server (NTRS)

    Dickerson, George E. (Inventor); Kelley, Henry L. (Inventor)

    1993-01-01

    A process for bonding elastomeric material to a metal part includes coating a heat curable adhesive on the surfaces of the metal part to be bonded. The metal part is placed in a mold, a bottom plate and an upper transfer pot of a transfer molding machine is preheated to a predetermined cure temperature. A predetermined quantity of uncured elastomeric material is loaded into the transfer pot. The mold containing the adhesive coated metal part is clamped to the bottom plate, and almost contemporaneously, the uncured elastomeric material is pressed into the mold while maintaining heat and pressure in the mold for a time sufficient to vulcanize and thereby cure the elastomeric material simultaneously with the adhesive, whereby contacting surfaces of the metal part are strongly bonded to the vulcanized elastomeric material.

  12. Femtosecond laser processing with a holographic line-shaped beam.

    PubMed

    Hasegawa, Satoshi; Shiono, Koji; Hayasaki, Yoshio

    2015-09-01

    Line-shaped femtosecond pulses are well-suited to large-area machining with high throughput in laser cutting, peeling, and grooving of materials. First, we demonstrated the single-shot fabrication of a line structure in a glass surface using a line-shaped pulse generated by a holographic cylindrical lens displayed on a liquid-crystal spatial light modulator. We found the line structure was uniform and smooth near the ends because of the ability to precisely control the intensity distribution and to achieve single-shot fabrication. Second, we demonstrated a line-shaped beam deformed three-dimensionally for showing the potential of holographic line-shaped beam processing. Third, we demonstrated laser peeling of an indium tin oxide film. We found that little debris around the fabricated area was observed, because the debris was removed by the beam itself. Last, we demonstrated laser grooving of stainless steel. We found the swelling of the surface included upwardly growing nanogratings, although many line-shaped pulse irradiations were given. The swelling was caused by the depositions of the debris on the top of the nanogratings.

  13. Shape-controlled synthesis of metal nanocrystals: simple chemistry meets complex physics?

    PubMed

    Xia, Younan; Xiong, Yujie; Lim, Byungkwon; Skrabalak, Sara E

    2009-01-01

    Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.

  14. Shape-Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?

    PubMed Central

    Xia, Younan; Xiong, Yujie; Lim, Byungkwon; Skrabalak, Sara E.

    2009-01-01

    Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. The aim of this article is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Toward the end of this article, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take. PMID:19053095

  15. On the Shape of Liquid Metal Droplets in Electromagnetic Levitation Experiments

    NASA Technical Reports Server (NTRS)

    Schwartz, E.; Sauerland, S.; Szekely, J.; Egry, I.

    1993-01-01

    We present calculations and measurements on the shape of liquid metal droplets in electromagnetic levitation experiments. A normal stress balance model was developed to predict the shapes of liquid metal droplets that will be obtained in a microgravity experiment to measure the viscosity and surface tension of undercooled metals. This model was tested by calculating the droplet shapes in containerless experiments conducted to determine the surface tension of liquid metals. Inconsistencies associated with the results of a previous paper are elucidated. The computational results of the mathematical model are compared with the results of ground-based experiments for two different metals. The importance of the ratio of electromagnetic skin depth-to-droplet radius to the accuracy of the mathematical model is discussed. A planned alternate approach to modeling the shape by consideration of the entire droplet rather than only the surface is presented. As an example of an application. the influence of the shape on the splitting of the surface oscillation modes of levitated liquid metal droplets is discussed.

  16. Investigation of Friction Stir Welding and Laser Engineered Net Shaping of Metal Matrix Composite Materials

    NASA Technical Reports Server (NTRS)

    Diwan, Ravinder M.

    2002-01-01

    prior set of operating conditions. Weld quality was evaluated using radiography and standard metallography techniques. Another aspect of the MMCs centered around the use of the laser engineered net shaping (LENS) processing of selected Narloy-Z composites. Such an approach has been earlier studied for fabrication of stainless steels. In the present study, attempts were made to fabricate straight cylindrical specimens using LENS process of Narloy-Z and Narloy-Z with 20 vol. % Al2O3 MMCs using the direct metal deposition Optomec LENS-750 system.

  17. Shaped ceramics with tunable magnetic properties from metal-containing polymers

    PubMed

    MacLachlan; Ginzburg; Coombs; Coyle; Raju; Greedan; Ozin; Manners

    2000-02-25

    A shaped, magnetic ceramic was obtained from a metal-containing polymer network, which was synthesized by thermal polymerization of a metal-containing organosilicon monomer. Pyrolysis of a cylinder, shape, or film of the metal-containing polymer precursor produced a low-density magnetic ceramic replica in high yield. The magnetic properties of the shaped ceramic could be tuned between a superparamagnetic and ferromagnetic state by controlling the pyrolysis conditions, with the particular state dependent on the size of iron nanoclusters homogeneously dispersed throughout the carbosilane-graphitic-silicon nitride matrix. These results indicate that cross-linked metal-containing polymers may be useful precursors to ceramic monoliths with tailorable magnetic properties. PMID:10688788

  18. Shaped Ceramics with Tunable Magnetic Properties from Metal-Containing Polymers

    NASA Astrophysics Data System (ADS)

    MacLachlan, Mark J.; Ginzburg, Madlen; Coombs, Neil; Coyle, Thomas W.; Raju, Nandyala P.; Greedan, John E.; Ozin, Geoffrey A.; Manners, Ian

    2000-02-01

    A shaped, magnetic ceramic was obtained from a metal-containing polymer network, which was synthesized by thermal polymerization of a metal-containing organosilicon monomer. Pyrolysis of a cylinder, shape, or film of the metal-containing polymer precursor produced a low-density magnetic ceramic replica in high yield. The magnetic properties of the shaped ceramic could be tuned between a superparamagnetic and ferromagnetic state by controlling the pyrolysis conditions, with the particular state dependent on the size of iron nanoclusters homogeneously dispersed throughout the carbosilane-graphitic-silicon nitride matrix. These results indicate that cross-linked metal-containing polymers may be useful precursors to ceramic monoliths with tailorable magnetic properties.

  19. Process for removing metals from water

    DOEpatents

    Napier, John M.; Hancher, Charles M.; Hackett, Gail D.

    1989-01-01

    A process for removing metals from water including the steps of prefiltering solids from the water, adjusting the pH to between about 2 and 3, reducing the amount of dissolved oxygen in the water, increasing the pH to between about 6 and 8, adding water-soluble sulfide to precipitate insoluble sulfide- and hydroxide-forming metals, adding a flocculating agent, separating precipitate-containing floc, and postfiltering the resultant solution. The postfiltered solution may optionally be eluted through an ion exchange resin to remove residual metal ions.

  20. Process for removing metals from water

    DOEpatents

    Napier, J.M.; Hancher, C.M.; Hackett, G.D.

    1987-06-29

    A process for removing metals from water including the steps of prefiltering solids from the water, adjusting the pH to between about 2 and 3, reducing the amount of dissolved oxygen in the water, increasing the pH to between about 6 and 8, adding water-soluble sulfide to precipitate insoluble sulfide- and hydroxide-forming metals, adding a containing floc, and postfiltering the resultant solution. The postfiltered solution may optionally be eluted through an ion exchange resin to remove residual metal ions. 2 tabs.

  1. PROCESS FOR TREATING VOLATILE METAL FLUORIDES

    DOEpatents

    Rudge, A.J.; Lowe, A.J.

    1957-10-01

    This patent relates to the purification of uranium hexafluoride, made by reacting the metal or its tetrafluoride with fluorine, from the frequently contained traces of hydrofluoric acid. According to the present process, UF/sub 6/ containing as an impurity a small amount of hydrofluoric acid, is treated to remove such impurity by contact with an anhydrous alkali metal fluoride such as sodium fluoride. In this way a non-volatile complex containing hydrofluoric acid and the alkali metal fluoride is formed, and the volatile UF /sub 6/ may then be removed by distillation.

  2. Process for etching mixed metal oxides

    DOEpatents

    Ashby, C.I.H.; Ginley, D.S.

    1994-10-18

    An etching process is described using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstrom range may be achieved by this method. 1 fig.

  3. Process for etching mixed metal oxides

    DOEpatents

    Ashby, Carol I. H.; Ginley, David S.

    1994-01-01

    An etching process using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstom range may be achieved by this method.

  4. Controlled Rejuvenation of Amorphous Metals with Thermal Processing

    PubMed Central

    Wakeda, Masato; Saida, Junji; Li, Ju; Ogata, Shigenobu

    2015-01-01

    Rejuvenation is the configurational excitation of amorphous materials and is one of the more promising approaches for improving the deformability of amorphous metals that usually exhibit macroscopic brittle fracture modes. Here, we propose a method to control the level of rejuvenation through systematic thermal processing and clarify the crucial feasibility conditions by means of molecular dynamics simulations of annealing and quenching. We also experimentally demonstrate rejuvenation level control in Zr55Al10Ni5Cu30 bulk metallic glass. Our local heat-treatment recipe (rising temperature above 1.1Tg, followed by a temperature quench rate exceeding the previous) opens avenue to modifying the glass properties after it has been cast and processed into near component shape, where a higher local cooling rate may be afforded by for example transient laser heating, adding spatial control and great flexibility to the processing. PMID:26010470

  5. Controlled Rejuvenation of Amorphous Metals with Thermal Processing

    NASA Astrophysics Data System (ADS)

    Wakeda, Masato; Saida, Junji; Li, Ju; Ogata, Shigenobu

    2015-05-01

    Rejuvenation is the configurational excitation of amorphous materials and is one of the more promising approaches for improving the deformability of amorphous metals that usually exhibit macroscopic brittle fracture modes. Here, we propose a method to control the level of rejuvenation through systematic thermal processing and clarify the crucial feasibility conditions by means of molecular dynamics simulations of annealing and quenching. We also experimentally demonstrate rejuvenation level control in Zr55Al10Ni5Cu30 bulk metallic glass. Our local heat-treatment recipe (rising temperature above 1.1Tg, followed by a temperature quench rate exceeding the previous) opens avenue to modifying the glass properties after it has been cast and processed into near component shape, where a higher local cooling rate may be afforded by for example transient laser heating, adding spatial control and great flexibility to the processing.

  6. Controlled rejuvenation of amorphous metals with thermal processing.

    PubMed

    Wakeda, Masato; Saida, Junji; Li, Ju; Ogata, Shigenobu

    2015-05-26

    Rejuvenation is the configurational excitation of amorphous materials and is one of the more promising approaches for improving the deformability of amorphous metals that usually exhibit macroscopic brittle fracture modes. Here, we propose a method to control the level of rejuvenation through systematic thermal processing and clarify the crucial feasibility conditions by means of molecular dynamics simulations of annealing and quenching. We also experimentally demonstrate rejuvenation level control in Zr(55)Al(10)Ni(5)Cu(30) bulk metallic glass. Our local heat-treatment recipe (rising temperature above 1.1T(g), followed by a temperature quench rate exceeding the previous) opens avenue to modifying the glass properties after it has been cast and processed into near component shape, where a higher local cooling rate may be afforded by for example transient laser heating, adding spatial control and great flexibility to the processing.

  7. Epoxy composite processing in a microwave part-shaped cavity

    SciTech Connect

    Shidaker, T.A.; Hawley, M.C.

    1997-12-31

    A microwave part-shaped applicator was designed to be competitive with conventional liquid composite molding processes. Three glass-reinforced diglycidyl ether of bisphenol A epoxy composites with a diaminodiphenyl sulfone curative are processed in the part-shaped cavity by microwave heating, conventional heating, and hybrid heating where both microwave and conduction heating are employed. Hybrid heating provided superior heating uniformity due to complementary heat transfer mechanisms: an outward flux of thermal energy from microwave heating combined with an inward flux of energy associated with conventional heating. Because of the penetrating nature of microwave energy, the time required to attain the cure temperature in the composite center was reduced by more than 85% using microwave and hybrid heating methods.

  8. Effect of Pin Tool Shape on Metal Flow During Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    McClure, J. C.; Coronado, E.; Aloor, S.; Nowak, B.; Murr, L. M.; Nunes, Arthur C., Jr.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    It has been shown that metal moves behind the rotating Friction Stir Pin Tool in two separate currents or streams. One current, mostly on the advancing side, enters a zone of material that rotates with the pin tool for one or more revolutions and eventually is abandoned behind the pin tool in crescent-shaped pieces. The other current, largely on the retreating side of the pin tool is moved by a wiping process to the back of the pin tool and fills in between the pieces of the rotational zone that have been shed by the rotational zone. This process was studied by using a faying surface copper trace to clarify the metal flow. Welds were made with pin tools having various thread pitches. Decreasing the thread pitch causes the large scale top-to-bottorn flow to break up into multiple vortices along the pin and an unthreaded pin tool provides insufficient vertical motion for there to be a stable rotational zone and flow of material via the rotational zone is not possible leading to porosity on the advancing side of the weld.

  9. New process hydrotreats metal-rich feedstocks

    SciTech Connect

    Langhout, W.C.V.Z.; Ouwerkerk, C.; Pronk, K.M.A.

    1980-01-01

    Shell Internationale Petroleum Maatschappij B.V. has developed a hydroprocessing procedure suitable for heavy residual feeds with metal contents of up to about 100 ppm, and Shell plans to introduce soon a process which will enable the catalytic hydrotreating of even the heaviest metal-rich feedstocks. This new process will be studied in an experimental unit expected to be on stream by the end of 1981 at a Venezuelan refinery. Also discussed are the catalytic hydroprocessing of residual material, including the roles of hydrodemetallization, h

  10. Liquid Metal Infiltration Processing of Metallic Composites: A Critical Review

    NASA Astrophysics Data System (ADS)

    Sree Manu, K. M.; Ajay Raag, L.; Rajan, T. P. D.; Gupta, Manoj; Pai, B. C.

    2016-07-01

    Metal matrix composites (MMC) are one of the advanced materials widely used for aerospace, automotive, defense, and general engineering applications. MMC can be tailored to have superior properties such as enhanced high-temperature performance, high specific strength and stiffness, increased wear resistance, better thermal and mechanical fatigue, and creep resistance than those of unreinforced alloys. To fabricate such composites with ideal properties, the processing technique has to ensure high volume fraction of reinforcement incorporation, uniform distribution of the reinforcement, and acceptable adhesion between the matrix and the reinforcing phase without unwanted interfacial reactions which degrades the mechanical properties. A number of processing techniques such as stir casting/vortex method, powder metallurgy, infiltration, casting etc. have been developed to synthesize MMC employing a variety of alloy and the reinforcement's combinations. Among these, infiltration process is widely used for making MMC with high volume fraction of reinforcements and offers many more advantages compared to other conventional manufacturing processes. The present paper critically reviews the various infiltration techniques used for making the MMC, their process parameters, characteristics, and selected studies carried out worldwide and by authors on the development of metal ceramic composites by squeeze infiltration process.

  11. Liquid Metal Infiltration Processing of Metallic Composites: A Critical Review

    NASA Astrophysics Data System (ADS)

    Sree Manu, K. M.; Ajay Raag, L.; Rajan, T. P. D.; Gupta, Manoj; Pai, B. C.

    2016-10-01

    Metal matrix composites (MMC) are one of the advanced materials widely used for aerospace, automotive, defense, and general engineering applications. MMC can be tailored to have superior properties such as enhanced high-temperature performance, high specific strength and stiffness, increased wear resistance, better thermal and mechanical fatigue, and creep resistance than those of unreinforced alloys. To fabricate such composites with ideal properties, the processing technique has to ensure high volume fraction of reinforcement incorporation, uniform distribution of the reinforcement, and acceptable adhesion between the matrix and the reinforcing phase without unwanted interfacial reactions which degrades the mechanical properties. A number of processing techniques such as stir casting/vortex method, powder metallurgy, infiltration, casting etc. have been developed to synthesize MMC employing a variety of alloy and the reinforcement's combinations. Among these, infiltration process is widely used for making MMC with high volume fraction of reinforcements and offers many more advantages compared to other conventional manufacturing processes. The present paper critically reviews the various infiltration techniques used for making the MMC, their process parameters, characteristics, and selected studies carried out worldwide and by authors on the development of metal ceramic composites by squeeze infiltration process.

  12. Process for production of a metal hydride

    SciTech Connect

    Allen, Nathan Tait; Butterick, III, Robert; Chin, Arthur Achhing; Millar, Dean Michael; Molzahn, David Craig

    2014-08-12

    A process for production of a metal hydride compound MH.sub.x, wherein x is one or two and M is an alkali metal, Be or Mg. The process comprises combining a compound of formula (R.sup.1O).sub.xM with aluminum, hydrogen and at least one metal selected from among titanium, zirconium, hafnium, niobium, vanadium, tantalum and iron to produce a compound of formula MH.sub.x. R.sup.1 is phenyl or phenyl substituted by at least one alkyl or alkoxy group. A mole ratio of aluminum to (R.sup.1O).sub.xM is from 0.1:1 to 1:1. The catalyst is present at a level of at least 200 ppm based on weight of aluminum.

  13. Shape-controlled continuous synthesis of metal nanostructures

    NASA Astrophysics Data System (ADS)

    Sebastian, Victor; Smith, Christopher D.; Jensen, Klavs F.

    2016-03-01

    A segmented flow-based microreactor is used for the continuous production of faceted nanocrystals. Flow segmentation is proposed as a versatile tool to manipulate the reduction kinetics and control the growth of faceted nanostructures; tuning the size and shape. Switching the gas from oxygen to carbon monoxide permits the adjustment in nanostructure growth from 1D (nanorods) to 2D (nanosheets). CO is a key factor in the formation of Pd nanosheets and Pt nanocubes; operating as a second phase, a reductant, and a capping agent. This combination confines the growth to specific structures. In addition, the segmented flow microfluidic reactor inherently has the ability to operate in a reproducible manner at elevated temperatures and pressures whilst confining potentially toxic reactants, such as CO, in nanoliter slugs. This continuous system successfully synthesised Pd nanorods with an aspect ratio of 6; thin palladium nanosheets with a thickness of 1.5 nm; and Pt nanocubes with a 5.6 nm edge length, all in a synthesis time as low as 150 s.A segmented flow-based microreactor is used for the continuous production of faceted nanocrystals. Flow segmentation is proposed as a versatile tool to manipulate the reduction kinetics and control the growth of faceted nanostructures; tuning the size and shape. Switching the gas from oxygen to carbon monoxide permits the adjustment in nanostructure growth from 1D (nanorods) to 2D (nanosheets). CO is a key factor in the formation of Pd nanosheets and Pt nanocubes; operating as a second phase, a reductant, and a capping agent. This combination confines the growth to specific structures. In addition, the segmented flow microfluidic reactor inherently has the ability to operate in a reproducible manner at elevated temperatures and pressures whilst confining potentially toxic reactants, such as CO, in nanoliter slugs. This continuous system successfully synthesised Pd nanorods with an aspect ratio of 6; thin palladium nanosheets with a

  14. Solidification Interface Shape and Location During Processing in High Gradient Furnace with Quench

    NASA Technical Reports Server (NTRS)

    Woodbury, Keith A.

    1996-01-01

    High Gradient Furnace with Quench (HGFQ) is being developed to facilitate metals processing experiments aboard the International Space Station. The sample is centered in an annular furnace and is held fixed during processing. The furnace itself is made to translate over the sample. Once in process, heat will flow through the sample from the Heater Zone to the Chill Zone. If operating conditions are correct, the solidification interface will stand in the gradient zone. Objectives of the HGFQ process are to provide a high gradient for the solidification with the solidification interface properly positioned in the gradient zone. At the recent RDR for HGFQ, one of the panelists raised the question about the suitability of HGFQ for potential future PIs. Specifically, it was stated by the design team at RDR that the present HGFQ design would provide a radius of curvature of the solidification interface of at least one sample diameter. The RDR panel argued that this was too small, and that most investigators would need a radius of curvature larger than this. The requirements established by the current PIs are shown. These requirements do not contain any specification about the interface shape. However, these requirements do define the envelope of operational parameters for HGFQ. The objectives of the present investigation are to 1) determine a suitable means of quantifying the interface shape, and 2) investigate the interface shape and how it is affected by processing parameters. The processing parameters to be considered are 1) sample material, 2) sample diameter, and 3) gradient zone length.

  15. Computer-aided analysis and design of the shape rolling process for producing turbine engine airfoils

    NASA Technical Reports Server (NTRS)

    Lahoti, G. D.; Akgerman, N.; Altan, T.

    1978-01-01

    Mild steel (AISI 1018) was selected as model cold rolling material and Ti-6A1-4V and Inconel 718 were selected as typical hot rolling and cold rolling alloys, respectively. The flow stress and workability of these alloys were characterized and friction factor at the roll/workpiece interface was determined at their respective working conditions by conducting ring tests. Computer-aided mathematical models for predicting metal flow and stresses, and for simulating the shape rolling process were developed. These models utilized the upper bound and the slab methods of analysis, and were capable of predicting the lateral spread, roll separating force, roll torque, and local stresses, strains and strain rates. This computer-aided design system was also capable of simulating the actual rolling process, and thereby designing the roll pass schedule in rolling of an airfoil or a similar shape.

  16. Investigation of nickel-silicon metallization process

    NASA Technical Reports Server (NTRS)

    Macha, M.

    1983-01-01

    The metallization of silicon solar cells passivated with silicon nitride coating was investigated by using commercial Ni pastes #5517 from Thick Film Systems, #7028-5 from Cermalloy, experimental formulation # X-A by Sollos, Inc. and evaporated Ti-Ni film. Comparative and reference tests were done with the Dupont Ag paste #7095 and with a mixture of Ni paste #5517 with Ag paste #7095 in the respective ratio of 9 to 1 by weight. The evaluation criteria for the metallization was the mechanical bond strength of the contact, solderability, copper plating ability and electrical characteristics in terms of Voc, Isc values and shape of the V-I curve. The results revealed that the Dupont Ag paste #7095 mt all required criteria, while the quality of the cells metalized with the commercial Ni paste #5517 from Thick Film Systems, #7028-5 from Cermalloy as well as the experimental paste # X-A from Sollos, Inc. was below the acceptable standards. A significant improvement was obtained with the mixture of Ni paste #5517 from Thick Film Systems with 10% addition of Dupont paste # 7095.

  17. Variation of the shape and morphological properties of silica and metal oxide powders by electro homogeneous precipitation

    DOEpatents

    Harris, M.T.; Basaran, O.A.; Sisson, W.G.; Brunson, R.R.

    1997-02-18

    The present invention provides a method for preparing irreversible linear aggregates (fibrils) of metal oxide powders by utilizing static or pulsed DC electrical fields across a relatively non-conducting liquid solvent in which organometal compounds or silicon alkoxides have been dissolved. The electric field is applied to the relatively non-conducting solution throughout the particle formation and growth process promoting the formation of either linear aggregates (fibrils) or spherical shaped particles as desired. Thus the present invention provides a physical method for altering the size, shape and porosity of precursor hydrous metal oxide or hydrous silicon oxide powders for the development of advanced ceramics with improved strength and insulating capacity. 3 figs.

  18. Morphing Metal and Elastomer Bicontinuous Foams for Reversible Stiffness, Shape Memory, and Self-Healing Soft Machines.

    PubMed

    Van Meerbeek, Ilse M; Mac Murray, Benjamin C; Kim, Jae Woo; Robinson, Sanlin S; Zou, Perry X; Silberstein, Meredith N; Shepherd, Robert F

    2016-04-13

    A metal-elastomer-foam composite that varies in stiffness, that can change shape and store shape memory, that self-heals, and that welds into monolithic structures from smaller components is presented. PMID:26872152

  19. Experimental and Numerical Investigation of Forging Process to Reproduce a 3D Aluminium Foam Complex Shape

    NASA Astrophysics Data System (ADS)

    Filice, Luigino; Gagliardi, Francesco; Shivpuri, Rajiv; Umbrello, Domenico

    2007-05-01

    Metallic foams represent one of the most exciting materials introduced in the manufacturing scenario in the last years. In the study here addressed, the experimental and numerical investigations on the forging process of a simple foam billet shaped into complex sculptured parts were carried out. In particular, the deformation behavior of metallic foams and the development of density gradients were investigated through a series of experimental forging tests in order to produce a selected portion of a hip prosthesis. The human bone replacement was chosen as case study due to its industrial demand and for its particular 3D complex shape. A finite element code (Deform 3D®) was utilized for modeling the foam behavior during the forging process and an accurate material rheology description was used based on a porous material model which includes the measured local density. Once the effectiveness of the utilized Finite Element model was verified through the comparison with the experimental evidences, a numerical study of the influence of the foam density was investigated. The obtained numerical results shown as the initial billet density plays an important role on the prediction of the final shape, the optimization of the flash as well as the estimation of the punch load.

  20. Experimental and Numerical Investigation of Forging Process to Reproduce a 3D Aluminium Foam Complex Shape

    SciTech Connect

    Filice, Luigino; Gagliardi, Francesco; Umbrello, Domenico; Shivpuri, Rajiv

    2007-05-17

    Metallic foams represent one of the most exciting materials introduced in the manufacturing scenario in the last years. In the study here addressed, the experimental and numerical investigations on the forging process of a simple foam billet shaped into complex sculptured parts were carried out. In particular, the deformation behavior of metallic foams and the development of density gradients were investigated through a series of experimental forging tests in order to produce a selected portion of a hip prosthesis. The human bone replacement was chosen as case study due to its industrial demand and for its particular 3D complex shape. A finite element code (Deform 3D) was utilized for modeling the foam behavior during the forging process and an accurate material rheology description was used based on a porous material model which includes the measured local density. Once the effectiveness of the utilized Finite Element model was verified through the comparison with the experimental evidences, a numerical study of the influence of the foam density was investigated. The obtained numerical results shown as the initial billet density plays an important role on the prediction of the final shape, the optimization of the flash as well as the estimation of the punch load.

  1. Sensing the gas metal arc welding process

    NASA Technical Reports Server (NTRS)

    Carlson, N. M.; Johnson, J. A.; Smartt, H. B.; Watkins, A. D.; Larsen, E. D.; Taylor, P. L.; Waddoups, M. A.

    1994-01-01

    Control of gas metal arc welding (GMAW) requires real-time sensing of the process. Three sensing techniques for GMAW are being developed at the Idaho National Engineering Laboratory (INEL). These are (1) noncontacting ultrasonic sensing using a laser/EMAT (electromagnetic acoustic transducer) to detect defects in the solidified weld on a pass-by-pass basis, (2) integrated optical sensing using a CCD camera and a laser stripe to obtain cooling rate and weld bead geometry information, and (3) monitoring fluctuations in digitized welding voltage data to detect the mode of metal droplet transfer and assure that the desired mass input is achieved.

  2. Process for Descaling and Decontaminating Metals

    DOEpatents

    Baybarz, R. D.

    1961-04-25

    The oxide scale on the surface of stainless steels and similar metals is removed by contacting the metal under an inert atmosphere with a dilute H/sub 2/ SO/sub 4/ solution containing CrSO/sub 4/. The removed oxide scale is either dissolved or disintegrated into a slurry by the solution. Preferred reagent concentrations are 0.3 to 0.5 M CrSO/sub 4/ and 0.5 to 0.6 M H/sub 2/SO/sub 4/. The process is particularly applicable to decontamination of aqueous homogeneous nuclear reactor systems. (AEC)

  3. Effects of d-band shape on the surface reactivity of transition-metal alloys

    NASA Astrophysics Data System (ADS)

    Xin, Hongliang; Vojvodic, Aleksandra; Voss, Johannes; Nørskov, Jens K.; Abild-Pedersen, Frank

    2014-03-01

    The d-band shape of a metal site, governed by the local geometry and composition of materials, plays an important role in determining trends of the surface reactivity of transition-metal alloys. We discuss this phenomenon using the chemisorption of various adsorbates such as C, N, O, and their hydrogenated species on Pd bimetallic alloys as an example. For many alloys, the d-band center, even with consideration of the d-band width and sp electrons, can not describe variations in reactivity from one surface to another. We investigate the effect of the d-band shape, represented by higher moments of the d band, on the local electronic structure of adsorbates, e.g., energy and filling of adsorbate-metal antibonding states. The upper d-band edge ɛu, defined as the highest peak position of the Hilbert transform of the density of states projected onto d orbitals of an active metal site, is identified as an electronic descriptor for the surface reactivity of transition metals and their alloys, regardless of variations in the d-band shape. The utilization of the upper d-band edge with scaling relations enables a considerable reduction of the parameter space in search of improved alloy catalysts and further extends our understanding of the relationship between the electronic structure and chemical reactivity of metal surfaces.

  4. Novel Processing of 81-mm Cu Shaped Charge Liners

    SciTech Connect

    Schwartz, A; Korzekwa, D

    2002-01-16

    A seven-step procedure was developed for producing shaped charge liner blanks by back extrusion at liquid nitrogen temperatures. Starting with a 38.1-mm diameter, 101.6-mm long cylinder at 77K, three forging steps with a flat-top die are required to produce the solid cone while maintaining low temperature. The solid cone is forged in four individual back extrusions at 77K to produce the rough liner blank. This procedure is capable of being run in batch processes to improve the time efficiency.

  5. Process for making silver metal filaments

    DOEpatents

    Bamberger, Carlos E.

    1997-01-01

    A process for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles.

  6. Process for making silver metal filaments

    SciTech Connect

    Bamberger, C.E.

    1997-05-06

    A process is disclosed for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles. 1 fig.

  7. Free form fabrication using the laser engineered net shaping (LENS{trademark}) process

    SciTech Connect

    Keicher, D.M.; Romero, J.A.; Atwood, C.L.; Griffith, M.L.; Jeantette, F.P.; Harwell, L.D.; Greene, D.L.; Smugeresky, J.E.

    1996-12-31

    Sandia National Laboratories is developing a technology called Laser Engineered Net Shaping{trademark} (LENS{trademark}). This process allows complex 3-dimensional solid metallic objects to be directly fabricated for a CAD solid model. Experiments performed demonstrate that complex alloys such as Inconel{trademark} 625 and ANSI stainless steel alloy 316 can be used in the LENS{trademark} process to produce solid metallic-shapes. In fact, the fabricated structures exhibit grain growth across the deposition layer boundaries. Mechanical testing data of deposited 316 stainless steel material indicates that the deposited material strength and elongation are greater than that reported for annealed 316 stainless steel. Electron microprobe analysis of the deposited Inconel{trademark} 625 material shows no compositional degradation of the 625 alloy and that 100% dense structures can be obtained using this technique. High speed imaging used to acquire process data during experimentation shows that the powder particle size range can significantly affect the stability, and subsequently, the performance of the powder deposition process. Finally, dimensional studies suggest that dimensional accuracy to {+-} 0.002 inches (in the horizontal direction) can be maintained.

  8. Near-Net-Shape Processing of Sintered Fibrous Ceramics Achieved

    NASA Technical Reports Server (NTRS)

    Angel, Paul W.

    2000-01-01

    A variety of sintered fibrous ceramic (SFC) materials have been developed over the last 50 years as thermal barrier materials for reentry applications. SFC materials typically exhibit very low thermal conductivities combined with low densities and good thermal stability up to 2500 F. These materials have flown successfully on the space shuttle orbiters since the 1960's. More recently, the McDonnell Douglas Corporation successfully used SFC tiles as a heat shield on the underside of its DC X test vehicle. For both of these applications, tiles are machined from blocks of a specific type of SFC called an alumina-enhanced thermal barrier (AETB). The sizes of these blocks have been limited by the manufacturing process. In addition, as much as 80 to 90 percent of the material can be lost during the machining of tiles with significant amounts of curvature. To address these problems, the NASA Glenn Research Center at Lewis Field entered a cooperative contract with the Boeing Company to develop a vacuum-assisted forming process that can produce large (approximately 4 square feet), severely contoured panels of AETB while saving costs in comparison to the conventional cast-and-machine billet process. For shuttle use, AETB is slurry cast, drained, and fired to form square billets conforming to the shape of the filtration box. The billets are then cut into tiles of the appropriate size for thermally protecting the space shuttle. Processing techniques have limited the maximum size of AETB billets to 21.5 square inches by 6.5-in. thick, but the space shuttles use discrete heat shield tiles no more than 8 to 12 square inches. However, in other applications, large, complex shapes are needed, and the tiling approach is undesirable. For such applications, vacuum-assisted forming can produce large parts with complex shapes while reducing machining waste and eliminating cemented joints between bonded billets. Because it allows contoured shapes to be formed, material utilization is

  9. Construction of 3D Metallic Nanostructures on an Arbitrarily Shaped Substrate.

    PubMed

    Chen, Fei; Li, Jingning; Yu, Fangfang; Zhao, Di; Wang, Fan; Chen, Yanbin; Peng, Ru-Wen; Wang, Mu

    2016-09-01

    Constructing conductive/magnetic nanowire arrays with 3D features by electrodeposition remains challenging. An unprecedented fabrication approach that allows to construct metallic (cobalt) nanowires on an arbitrarily shaped surface is reported. The spatial separation of nanowires varies from 70 to 3000 nm and the line width changes from 50 to 250 nm depending on growth conditions. PMID:27294561

  10. PROCESS OF ELECTROPLATING METALS WITH ALUMINUM

    DOEpatents

    Schickner, W.C.

    1960-04-26

    A process of electroplating aluminum on metals from a nonaqueous bath and a novel method of pretreating or conditioning the metal prior to electrodeposition of the aluminum are given. The process of this invention, as applied by way of example to the plating of uranium, comprises the steps of plating the uranium with the barrier inetal, immersing the barrier-coated uranium in fatty acid, and electrolyzing a water-free diethyl ether solution of aluminum chloride and lithium hydride while making the uranium the cathode until an aluminum deposit of the desired thickness has been formed. According to another preferred embodiment the barrier-coated uranium is immersed in an isopropyl alcohol solution of sterato chromic chloride prior to the fatty acid treatment of this invention.

  11. Reduction of metal oxides through mechanochemical processing

    DOEpatents

    Froes, Francis H.; Eranezhuth, Baburaj G.; Senkov, Oleg N.

    2000-01-01

    The low temperature reduction of a metal oxide using mechanochemical processing techniques. The reduction reactions are induced mechanically by milling the reactants. In one embodiment of the invention, titanium oxide TiO.sub.2 is milled with CaH.sub.2 to produce TiH.sub.2. Low temperature heat treating, in the range of 400.degree. C. to 700.degree. C., can be used to remove the hydrogen in the titanium hydride.

  12. Architectural design of heterogeneous metallic nanocrystals--principles and processes.

    PubMed

    Yu, Yue; Zhang, Qingbo; Yao, Qiaofeng; Xie, Jianping; Lee, Jim Yang

    2014-12-16

    CONSPECTUS: Heterogeneous metal nanocrystals (HMNCs) are a natural extension of simple metal nanocrystals (NCs), but as a research topic, they have been much less explored until recently. HMNCs are formed by integrating metal NCs of different compositions into a common entity, similar to the way atoms are bonded to form molecules. HMNCs can be built to exhibit an unprecedented architectural diversity and complexity by programming the arrangement of the NC building blocks ("unit NCs"). The architectural engineering of HMNCs involves the design and fabrication of the architecture-determining elements (ADEs), i.e., unit NCs with precise control of shape and size, and their relative positions in the design. Similar to molecular engineering, where structural diversity is used to create more property variations for application explorations, the architectural engineering of HMNCs can similarly increase the utility of metal NCs by offering a suite of properties to support multifunctionality in applications. The architectural engineering of HMNCs calls for processes and operations that can execute the design. Some enabling technologies already exist in the form of classical micro- and macroscale fabrication techniques, such as masking and etching. These processes, when used singly or in combination, are fully capable of fabricating nanoscopic objects. What is needed is a detailed understanding of the engineering control of ADEs and the translation of these principles into actual processes. For simplicity of execution, these processes should be integrated into a common reaction system and yet retain independence of control. The key to architectural diversity is therefore the independent controllability of each ADE in the design blueprint. The right chemical tools must be applied under the right circumstances in order to achieve the desired outcome. In this Account, after a short illustration of the infinite possibility of combining different ADEs to create HMNC design

  13. Architectural design of heterogeneous metallic nanocrystals--principles and processes.

    PubMed

    Yu, Yue; Zhang, Qingbo; Yao, Qiaofeng; Xie, Jianping; Lee, Jim Yang

    2014-12-16

    CONSPECTUS: Heterogeneous metal nanocrystals (HMNCs) are a natural extension of simple metal nanocrystals (NCs), but as a research topic, they have been much less explored until recently. HMNCs are formed by integrating metal NCs of different compositions into a common entity, similar to the way atoms are bonded to form molecules. HMNCs can be built to exhibit an unprecedented architectural diversity and complexity by programming the arrangement of the NC building blocks ("unit NCs"). The architectural engineering of HMNCs involves the design and fabrication of the architecture-determining elements (ADEs), i.e., unit NCs with precise control of shape and size, and their relative positions in the design. Similar to molecular engineering, where structural diversity is used to create more property variations for application explorations, the architectural engineering of HMNCs can similarly increase the utility of metal NCs by offering a suite of properties to support multifunctionality in applications. The architectural engineering of HMNCs calls for processes and operations that can execute the design. Some enabling technologies already exist in the form of classical micro- and macroscale fabrication techniques, such as masking and etching. These processes, when used singly or in combination, are fully capable of fabricating nanoscopic objects. What is needed is a detailed understanding of the engineering control of ADEs and the translation of these principles into actual processes. For simplicity of execution, these processes should be integrated into a common reaction system and yet retain independence of control. The key to architectural diversity is therefore the independent controllability of each ADE in the design blueprint. The right chemical tools must be applied under the right circumstances in order to achieve the desired outcome. In this Account, after a short illustration of the infinite possibility of combining different ADEs to create HMNC design

  14. Near-Net-Shape Production of Hollow Titanium Alloy Components via Electrochemical Reduction of Metal Oxide Precursors in Molten Salts

    NASA Astrophysics Data System (ADS)

    Hu, Di; Xiao, Wei; Chen, George Z.

    2013-04-01

    Metal oxide precursors (ca. 90 wt pct Ti, 6 wt pct Al, and 4 wt pct V) were prepared with a hollow structure in various shapes such as a sphere, miniature golf club head, and cup using a one-step solid slip-casting process. The precursors were then electro-deoxidized in molten calcium chloride [3.2 V, 1173 K (900 °C)] against a graphite anode. After 24 hours of electrolysis, the near-net-shape Ti-6Al-4V product maintained its original shape with controlled shrinkage. Oxygen contents in the Ti-6Al-4V components were typically below 2000 ppm. The maximum compressive stress and modulus of electrolytic products obtained in this work were approximately 243 MPa and 14 GPa, respectively, matching with the requirement for medical implants. Further research directions are discussed for mechanical improvement of the products via densification during or after electrolysis. This simple, fast, and energy-efficient near-net-shape manufacturing method could allow titanium alloy components with desired geometries to be prepared directly from a mixture of metal oxides, promising an innovative technology for the low-cost production of titanium alloy components.

  15. Solar Convective Furnace for Metals Processing

    NASA Astrophysics Data System (ADS)

    Patidar, Deepesh; Tiwari, Sheetanshu; Sharma, Piyush; Pardeshi, Ravindra; Chandra, Laltu; Shekhar, Rajiv

    2015-11-01

    Metals processing operations, primarily soaking, heat treatment, and melting of metals are energy-intensive processes using fossil fuels, either directly or indirectly as electricity, to operate furnaces at high temperatures. Use of concentrated solar energy as a source of heat could be a viable "green" option for industrial heat treatment furnaces. This paper introduces the concept of a solar convective furnace which utilizes hot air generated by an open volumetric air receiver (OVAR)-based solar tower technology. The potential for heating air above 1000°C exists. Air temperatures of 700°C have already been achieved in a 1.5-MWe volumetric air receiver demonstration plant. Efforts to retrofit an industrial aluminium soaking furnace for integration with a solar tower system are briefly described. The design and performance of an OVAR has been discussed. A strategy for designing a 1/15th-scale model of an industrial aluminium soaking furnace has been presented. Preliminary flow and thermal simulation results suggest the presence of recirculating flow in existing furnaces that could possibly result in non-uniform heating of the slabs. The multifarious uses of concentrated solar energy, for example in smelting, metals processing, and even fuel production, should enable it to overcome its cost disadvantage with respect to solar photovoltaics.

  16. Metal containing material processing on coater/developer system

    NASA Astrophysics Data System (ADS)

    Kawakami, Shinichiro; Mizunoura, Hiroshi; Matsunaga, Koichi; Hontake, Koichi; Nakamura, Hiroshi; Shimura, Satoru; Enomoto, Masashi

    2016-03-01

    Challenges of processing metal containing materials need to be addressed in order apply this technology to Behavior of metal containing materials on coater/developer processing including coating process, developer process and tool metal contamination is studied using CLEAN TRACKTM LITHIUS ProTM Z (Tokyo Electron Limited). Through this work, coating uniformity and coating film defectivity were studied. Metal containing material performance was comparable to conventional materials. Especially, new dispense system (NDS) demonstrated up to 80% reduction in coating defect for metal containing materials. As for processed wafer metal contamination, coated wafer metal contamination achieved less than 1.0E10 atoms/cm2 with 3 materials. After develop metal contamination also achieved less than 1.0E10 atoms/cm2 with 2 materials. Furthermore, through the metal defect study, metal residues and metal contamination were reduced by developer rinse optimization.

  17. Process for forming shaped group II-VI semiconductor nanocrystals, and product formed using process

    DOEpatents

    Alivisatos, A. Paul; Peng, Xiaogang; Manna, Liberato

    2001-01-01

    A process for the formation of shaped Group II-VI semiconductor nanocrystals comprises contacting the semiconductor nanocrystal precursors with a liquid media comprising a binary mixture of phosphorus-containing organic surfactants capable of promoting the growth of either spherical semiconductor nanocrystals or rod-like semiconductor nanocrystals, whereby the shape of the semiconductor nanocrystals formed in said binary mixture of surfactants is controlled by adjusting the ratio of the surfactants in the binary mixture.

  18. Process for forming shaped group III-V semiconductor nanocrystals, and product formed using process

    DOEpatents

    Alivisatos, A. Paul; Peng, Xiaogang; Manna, Liberato

    2001-01-01

    A process for the formation of shaped Group III-V semiconductor nanocrystals comprises contacting the semiconductor nanocrystal precursors with a liquid media comprising a binary mixture of phosphorus-containing organic surfactants capable of promoting the growth of either spherical semiconductor nanocrystals or rod-like semiconductor nanocrystals, whereby the shape of the semiconductor nanocrystals formed in said binary mixture of surfactants is controlled by adjusting the ratio of the surfactants in the binary mixture.

  19. Using the Laser Engineered Net Shaping (LENS{trademark}) process to produce complex components from a CAD solid model

    SciTech Connect

    Smugeresky, J.E.; Keicher, D.M.; Romero, J.A.; Griffith, M.L.; Harwell, L.D.

    1997-08-01

    The Laser Engineered Net Shaping (LENS{trademark}) process, currently under development, has demonstrated the capability to produce near-net shape, fully dense metallic parts with reasonably complex geometrical features directly from a Computer-Aided Design (CAD) solid model. Using a highly localized laser beam, metal powders are used to produce very fine grain high strength structures. Results to date show that excellent mechanical properties can be achieved in alloys such as 316 stainless steel and Inconel 625. Significant increases in yield strength have been achieved with no loss in ductility. The current approach lends itself to produce components with a dimensional accuracy of {+-} 0.002 inches in the deposition plane and {+-} 0.015 inches in the growth direction. These results suggest that the LENS{trademark} process will provide a viable means for direct fabrication of metallic hardware.

  20. Tailored processing of epoxy with embedded shape memory alloy wires

    NASA Astrophysics Data System (ADS)

    Kirkby, E. L.; O'Keane, J.; de Oliveira, R.; Michaud, V. J.; Månson, J.-A. E.

    2009-09-01

    We present the development of a low-temperature liquid composite moulding cure schedule that is compatible with the fabrication of shape memory alloy (SMA)-epoxy composite materials. With this process, the SMA wires do not need to be maintained in place with an external frame, even though the peak post-cure temperature exceeds the activation temperature of the SMA wires. The intrinsic interfacial shear strength of the final material is experimentally determined from single wire pull-out tests, and is compared with the shear stress exerted at the interface by an activated SMA wire. These measurements show that the interface is strong enough to withstand the maximum activation stress. This is confirmed through tests involving the cyclic activation of SMA wires embedded in epoxy samples. The paper successfully demonstrates that, by careful tailoring of the processing schedule, an SMA-epoxy composite that maintains a strong interfacial bond during both processing and subsequent activation of the embedded wires can be fabricated using standard composite processing methods.

  1. Liquid metals as ultra-stretchable, soft, and shape reconfigurable conductors

    NASA Astrophysics Data System (ADS)

    Eaker, Collin B.; Dickey, Michael D.

    2015-05-01

    Conventional, rigid materials remain the key building blocks of most modern electronic devices, but they are limited in their ability to conform to curvilinear surfaces. It is possible to make electronic components that are flexible and in some cases stretchable by utilizing thin films, engineered geometries, or inherently soft and stretchable materials that maintain their function during deformation. Here, we describe the properties and applications of a micromoldable liquid metal that can form conductive components that are ultra-stretchable, soft, and shape-reconfigurable. This liquid metal is a gallium-based alloy with low viscosity and high conductivity. The metal develops spontaneously a thin, passivating oxide layer on the surface that allows the metal to be molded into non-spherical shapes, including films and wires, and patterned by direct-write techniques or microfluidic injection. Furthermore, unlike mercury, the liquid metal has low toxicity and negligible vapor pressure. This paper discusses the mechanical and electrical properties of the metal in the context of electronics, and discusses how the properties of the oxide layer have been exploited for new patterning techniques that enable soft, stretchable and reconfigurable devices.

  2. Direct selective laser sintering of high performance metals: Machine design, process development and process control

    NASA Astrophysics Data System (ADS)

    Das, Suman

    1998-11-01

    This dissertation describes the development of an advanced manufacturing technology known as Direct Selective Laser Sintering (Direct SLS). Direct SLS is a laser based rapid manufacturing technology that enables production of functional, fully dense, metal and cermet components via the direct, layerwise consolidation of constituent powders. Specifically, this dissertation focuses on a new, hybrid net shape manufacturing technique known as Selective Laser Sintering/Hot Isostatic Pressing (SLS/HIP). The objective of research presented in this dissertation was to establish the fundamental machine technology and processing science to enable direct SLS fabrication of metal components composed of high performance, high temperature metals and alloys. Several processing requirements differentiate direct SLS of metals from SLS of polymers or polymer coated powders. Perhaps the most important distinguishing characteristic is the regime of high temperatures involved in direct SLS of metals. Biasing the temperature of the feedstock powder via radiant preheat prior to and during SLS processing was shown to be beneficial. Preheating the powder significantly influenced the flow and wetting characteristics of the melt. During this work, it was conclusively established that powder cleanliness is of paramount importance for successful layerwise consolidation of metal powders by direct SLS. Sequential trials were conducted to establish optimal bake-out and degas cycles under high vacuum. These cycles agreed well with established practices in the powder metallurgy industry. A study of some of the important transport mechanisms in direct SLS of metals was undertaken to obtain a fundamental understanding of the underlying process physics. This study not only provides an explanation of phenomena observed during SLS processing of a variety of metallic materials but also helps in developing selection schemes for those materials that are most amenable to direct SLS processing. The

  3. A fabrication method of unique Nafion shapes by painting for ionic polymer-metal composites (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Trabia, Sarah; Hwang, Taeseon; Kim, Kwang Jin

    2016-04-01

    Ionic Polymer-Metal Composites (IPMC) are useful actuators because of their ability to be fabricated in different shapes and move in various ways. However, the process to produce an IPMC is complicated and takes a few days. To make it possible to mass produce in any desired shape, the fabrication process must be updated. Presented here is a new way of producing the Nafion® base through a spraying method, then the electrode will be plated with spraying method as well. To verify that this method of fabrication produces a Nafion® sample similar to that which is commercially available, a sample that was made using spraying method and N117 purchased from DuPont™ were tested for various characteristics and compared.

  4. Dimensional Stability of Complex Shapes Manufactured by the VARTM Process

    NASA Technical Reports Server (NTRS)

    Hubert, Pascal; Grimsley, Brian W.; Cano, Roberto J.; Pipes, R. Byron

    2002-01-01

    The vacuum assisted resin transfer molding (VARTM) process is a cost effective, innovative method that is being considered for manufacture of large aircraft-quality components where high mechanical properties and dimensional tolerance are essential. In the present work, carbon fiber SAERTEX fabric/SI-ZG-5A epoxy resin C-shaped laminates were manufactured by VARTM using different cure cycles followed by the same post-cure cycle. The final part thickness was uniform except at the corner were thinning was observed. The cure cycle selected is shown to significantly affect the part spring-in and a long cycle at 66 C followed by a 178 C post-cure produced a part with negligible spring-in.

  5. Process for recovering metals from solution utilizing metalloprotein affinity chromatography

    SciTech Connect

    Spears, D.R.; Vincent, J.B.

    1993-11-29

    The invention relates generally to a process for recovering metals from an aqueous metal-bearing solution and, more particularly, to a process which utilizes metalloproteins immobilized on an insoluble support to remove metal ions such as the main group, transition, lanthanide, and actinide ions from the aqueous metal-ion bearing solution.

  6. Native language shapes automatic neural processing of speech.

    PubMed

    Intartaglia, Bastien; White-Schwoch, Travis; Meunier, Christine; Roman, Stéphane; Kraus, Nina; Schön, Daniele

    2016-08-01

    The development of the phoneme inventory is driven by the acoustic-phonetic properties of one's native language. Neural representation of speech is known to be shaped by language experience, as indexed by cortical responses, and recent studies suggest that subcortical processing also exhibits this attunement to native language. However, most work to date has focused on the differences between tonal and non-tonal languages that use pitch variations to convey phonemic categories. The aim of this cross-language study is to determine whether subcortical encoding of speech sounds is sensitive to language experience by comparing native speakers of two non-tonal languages (French and English). We hypothesized that neural representations would be more robust and fine-grained for speech sounds that belong to the native phonemic inventory of the listener, and especially for the dimensions that are phonetically relevant to the listener such as high frequency components. We recorded neural responses of American English and French native speakers, listening to natural syllables of both languages. Results showed that, independently of the stimulus, American participants exhibited greater neural representation of the fundamental frequency compared to French participants, consistent with the importance of the fundamental frequency to convey stress patterns in English. Furthermore, participants showed more robust encoding and more precise spectral representations of the first formant when listening to the syllable of their native language as compared to non-native language. These results align with the hypothesis that language experience shapes sensory processing of speech and that this plasticity occurs as a function of what is meaningful to a listener. PMID:27263123

  7. Application of the metal compression forming process for the production of an aluminum alloy component

    SciTech Connect

    Viswanathan, S.; Porter, W.D.; Ren, W.; Purgert, R.M.

    1997-01-01

    Metal Compression Forming (MCF) is a variant of the squeeze casting process, in which molten metal is allowed to solidify under pressure in order to close porosity and form a sound part. MCF applies pressure on the entire mold face, thereby directing pressure on all regions of the casting. It also enhances the solidification rate of the metal, promoting a very fine grain structure which results in improved properties. Consequently, the process is capable of producing parts with properties close to that of forgings, while retaining the near net shape, complex geometry, and relatively low cost of the casting process.

  8. Formation of heteroepitaxy in different shapes of Au-CdSe metal-semiconductor hybrid nanostructures.

    PubMed

    Haldar, Krishna Kanta; Pradhan, Narayan; Patra, Amitava

    2013-10-25

    Formation of heteroepitaxy and designing different-shaped heterostructured nanomaterials of metal and semiconductor in solution remains a frontier area of research. However, it is evident that the synthesis of such materials is not straightforward and needs a selective approach to retain both metal and semiconductor identities in the reaction system during heterostructure formation. Herein, the epitaxial growth of semiconductor CdSe on selected facets of metal Au seeds is reported and different shapes (flower, tetrapod, and core/shell) hetero-nanostructures are designed. These results are achieved by controlling the reaction parameters, and by changing the sequence and timing for introduction of different reactant precursors. Direct evidence of the formation of heteroepitaxy between {111} facets of Au and (0001) of wurtzite CdSe is observed during the formation of these three heterostructures. The mechanism of the evolution of these hetero-nanostructures and formation of their heteroepitaxy with the planes having minimum lattice mismatch are also discussed. This shape-control growth mechanism in hetero-nanostructures should be helpful to provide more information for establishing the fundamental study of heteroepitaxial growth for designing new nanomaterials. Such metal-semiconductor nanostructures may have great potential for nonlinear optical properties, in photovoltaic devices, and as chemical sensors.

  9. Process Of Bonding A Metal Brush Structure To A Planar Surface Of A Metal Substrate

    DOEpatents

    Slattery, Kevin T.; Driemeyer, Daniel E.; Wille; Gerald W.

    1999-11-02

    Process for bonding a metal brush structure to a planar surface of a metal substrate in which an array of metal rods are retained and immobilized at their tips by a common retention layer formed of metal, and the brush structure is then joined to a planar surface of a metal substrate via the retention layer.

  10. Realization of multifunctional shape-memory ferromagnets in all-d-metal Heusler phases

    SciTech Connect

    Wei, Z. Y.; Liu, E. K. Chen, J. H.; Xi, X. K.; Zhang, H. W.; Wang, W. H.; Wu, G. H.; Li, Y.; Liu, G. D.; Luo, H. Z.

    2015-07-13

    Heusler ferromagnetic shape-memory alloys (FSMAs) normally consist of transition-group d-metals and main-group p-elements. Here, we report the realization of FSMAs in Heusler phases that completely consist of d metals. By introducing the d-metal Ti into NiMn alloys, cubic B2-type Heusler phase is obtained and the martensitic transformation temperature is decreased efficiently. Strong ferromagnetism is established by further doping Co atoms into the B2-type antiferromagnetic Ni-Mn-Ti austenite. Based on the magnetic-field-induced martensitic transformations, collective multifunctional properties are observed in Ni(Co)-Mn-Ti alloys. The d metals not only facilitate the formation of B2-type Heusler phases but also establish strong ferromagnetic coupling and offer the possibility to tune the martensitic transformation.

  11. The shape factor influence on the control process of multiferroic nanoparticle configurations in GHz range

    NASA Astrophysics Data System (ADS)

    Ionescu, D.; Kovaci, M.

    2015-11-01

    Materials with piezoelectric properties associated with the ferroic phases generate multiferroic structures at microscopic level. Multiferroic core-shell nanoparticles with different configurations were considered: nanospheres versus nanotubes - spherical (magnetostrictive core / piezoelectric shell), respectively cylindrical (magnetostrictive rod / piezoelectric cylindrical coating) The external sphere diameter / cylinder lengths were of 80 - 100 nm to 360 nm, while the inner sphere / rod diameters were of 20 to 60 nm. The influence of the constituents shape on their control process realized by an applied magnetic field, H0 (100 - 270 Oe) was investigated. The nanoparticles were simulated using the HFSS 13.0 program, at frequencies in microwave range (16 - 28 GHz), considering the nanostructures with hexaferrites as magnetic phase (AFe12O19 M-type hexaferrites, with A an alkali earth metal) and the Bi2NiMnO6 perovskite like piezoelectric. The particle configurations response is function of their geometrical shape, modified by the core diameter and the shell thickness. The magnetoelectric (ME) coefficient tensor has been determined using a physical algorithm based on the near-filed values in the particles vicinity, generated by the HFSS, and also the ME voltage coefficient (obtained of tens of mV/cmOe). Performance of the two shapes composite nanoparticles to generate a strong ME response was discussed comparatively and the influence of the shape factor was illustrated on graphs. Each composite configuration presents specific advantages in respect with the control process by the H0 field, considering that the effect of dipolar field generated as response by the electric phase is strongly anisotropic. These features can be elegant illustrated by simulations (non destructive, applied at nanoscale) which help us to decide to the proper nanoparticles shape and the optimal intensity of the applied fields for the desired strength of the ME effect in a defined microscopic

  12. Topochemistry of Bowtie- and Star-Shaped Metal Dichalcogenide Nanoisland Formation.

    PubMed

    Artyukhov, Vasilii I; Hu, Zhili; Zhang, Zhuhua; Yakobson, Boris I

    2016-06-01

    A large number of experimental studies over the past few years observed the formation of unusual highly symmetric polycrystalline twinned nanoislands of transition metal dichalcogenides, resembling bowties or stars. Here, we analyze their morphology in terms of equilibrium and growth shapes. We propose a mechanism for these complex shapes' formation via collision of concurrently growing islands and validate the theory with phase-field simulations that demonstrate how highly symmetric structures can actually emerge from arbitrary starting conditions. Finally, we use first-principles calculations to propose an explanation of the predominance of high-symmetry polycrystals with 60° lattice misorientation angles. PMID:27187078

  13. Microwave and camera sensor fusion for the shape extraction of metallic 3D space objects

    NASA Technical Reports Server (NTRS)

    Shaw, Scott W.; Defigueiredo, Rui J. P.; Krishen, Kumar

    1989-01-01

    The vacuum of space presents special problems for optical image sensors. Metallic objects in this environment can produce intense specular reflections and deep shadows. By combining the polarized RCS with an incomplete camera image, it has become possible to better determine the shape of some simple three-dimensional objects. The radar data are used in an iterative procedure that generates successive approximations to the target shape by minimizing the error between computed scattering cross-sections and the observed radar returns. Favorable results have been obtained for simulations and experiments reconstructing plates, ellipsoids, and arbitrary surfaces.

  14. Hybrid Al + Al3Ni metallic foams synthesized in situ via laser engineered net shaping

    NASA Astrophysics Data System (ADS)

    Zheng, Baolong; Li, Ying; Smugeresky, John E.; Zhou, Yizhang; Baker, Dean; Lavernia, Enrique J.

    2011-09-01

    A hybrid, Al + Al3Ni metallic foam was synthesized in situ via laser engineered net shaping (LENS®) of Ni-coated 6061 Al powder in the absence of a foaming agent. During LENS® processing, the Ni coating reacted with the Al matrix, resulting in the simultaneous formation of a fine dispersion of Al3Ni, and a high volume fraction of porosity. As a reinforcement phase, the intermetallic compound formed particles with a size range of 1-5 µm and a volume fraction of 63%, with accompanying 35-300 µm pores with a 60% volume fraction. The microstructure of the as-deposited Al + Al3Ni composite foams was characterized using SEM, EDS, XRD and TEM/HRTEM techniques. The evolution of the microstructure was analyzed on the basis of the thermal field present during deposition, paying particular attention to the thermodynamics of the Al3Ni intermetallic compound formation as well as discussing the mechanisms that may be responsible for the observed porosity. The mechanical behavior of the as-deposited material was characterized using compression and microhardness testing, indicating that the yield strength and hardness are 190 MPa and 320 HV, respectively, which represents an increase of over three times higher than that of annealed Al6061, or similar to heat-treated Al6061 fully dense matrix, and much higher than those of traditional Al alloy foams, and with a low density of 1.64 g/m3.

  15. Parameters in selective laser melting for processing metallic powders

    NASA Astrophysics Data System (ADS)

    Kurzynowski, Tomasz; Chlebus, Edward; Kuźnicka, Bogumiła; Reiner, Jacek

    2012-03-01

    The paper presents results of studies on Selective Laser Melting. SLM is an additive manufacturing technology which may be used to process almost all metallic materials in the form of powder. Types of energy emission sources, mainly fiber lasers and/or Nd:YAG laser with similar characteristics and the wavelength of 1,06 - 1,08 microns, are provided primarily for processing metallic powder materials with high absorption of laser radiation. The paper presents results of selected variable parameters (laser power, scanning time, scanning strategy) and fixed parameters such as the protective atmosphere (argon, nitrogen, helium), temperature, type and shape of the powder material. The thematic scope is very broad, so the work was focused on optimizing the process of selective laser micrometallurgy for producing fully dense parts. The density is closely linked with other two conditions: discontinuity of the microstructure (microcracks) and stability (repeatability) of the process. Materials used for the research were stainless steel 316L (AISI), tool steel H13 (AISI), and titanium alloy Ti6Al7Nb (ISO 5832-11). Studies were performed with a scanning electron microscope, a light microscopes, a confocal microscope and a μCT scanner.

  16. Laser engineered net shaping (LENS) for the fabrication of metallic components

    SciTech Connect

    Griffith, M.L.; Keicher, D.L.; Romero, J.A.; Atwood, C.L.; Harwell, L.D.; Greene, D.L.; Smugeresky, J.E.

    1996-06-01

    Solid free form fabrication is a fast growing automated manufacturing technology that has reduced the time between initial concept and fabrication. Starting with CAD renditions of new components, techniques such as stereolithography and selective laser sintering are being used to fabricate highly accurate complex 3-D objects using polymers. Together with investment casting, sacrificial polymeric objects are used to minimize cost and time to fabricate tooling used to make complex metal casting. This paper describes recent developments in LENS{trademark} (Laser Engineered Net Shaping) to fabricate the metal components {ital directly} from CAD solid models and thus further reduce the lead time. Like stereolithography or selective sintering, LENS builds metal parts line by line and layer by layer. Metal particles are injected into a laser beam where they are melted and deposited onto a substrate as a miniature weld pool. The trace of the laser beam on the substrate is driven by the definition of CAD models until the desired net-shaped densified metal component is produced.

  17. Laser-assisted solar cell metallization processing

    NASA Technical Reports Server (NTRS)

    Meier, D. L.

    1986-01-01

    The status of the laser-assisted solar cell metallization processing is described. Metallo-organic silver films were spun-on by argon ion laser beam pyrolysis. The metallo-organic decomposition (MOD) film was spun-on an evaporated Ti/Pd film to produce tood adhesion. In a maskless process, the argon ion laser writes the contact pattern. The film is then built up to obtain the required conductivity using conventional silverplating process. The Ti/Pd film in the field is chemically etched using the plated silver film as the mask. The width of the contact pattern is determined by the power of the laser. Widths as thin as 20 microns were obtained using 0.66 W of laser power. Cells fabricated with the 50 micron line widths of 4 ohm-cm floating zone (Fz) silicon-produced efficiencies of 16.6% (no passivation) which were equivalent to the best cells using conventional metallization/lithography and no passivation.

  18. Heavy metals processing near-net-forming summary progress report

    SciTech Connect

    Watson, L.D.; Thompson, J.E.

    1994-09-01

    This study utilized a converging-diverging nozzle to spray-form an alloy having a weight percent composition of 49.6% iron, 49.6% tungsten, and 0.8% carbon into samples for analysis. The alloy was a surrogate that displayed metallurgical characteristics similar to the alloys used in the heavy metals processing industry. US DOE facilities are evaluating advanced technologies which can simplify component fabrication, reduce handling steps, and minimize final machining. The goal of producing net-shaped components can be approached from several directions. In spray forming, molten metal is converted by a nozzle into a plume of fine droplets which quickly cool in flight and solidify against a substrate. The near-final dimension product that is formed receives additional benefits from rapid solidification. This single-step processing approach would aid the heavy metals industry by streamlining fabrication, improving production yields, and minimizing the generation of processing wastes. This Program effort provided a large selection of as-sprayed specimens. These samples were sprayed with gas-to-metal mass ratios ranging from 0.8:1 to 4:1. Samples targeted for analysis were produced from different spray conditions. Metallography on some samples revealed areas that were fully dense and homogeneous at 5,000X. These areas averaged grain sizes of 1 micron diameter. Other samples when viewed at 2,000X were highly segregated in the 10 micron diameter range. Deposit efficiencies of greater than 90% were demonstrated using the untailored spray system. Discharge gases were analyzed and two categories of particles were identified. One category of particle had a chemical composition characteristic of the alloy being sprayed and the second type of particle had a chemical composition characteristic of the ceramics used in the spray system component fabrication. Particles ranged in size from 0.07 to 3 microns in diameter. 8 refs., 67 figs., 20 tabs.

  19. Computer-aided analysis and design of the shape rolling process for producing turbine engine airfoils

    NASA Technical Reports Server (NTRS)

    Lahoti, G. D.; Akgerman, N.; Altan, T.

    1978-01-01

    Mild steel (AISI 1018) was selected as model cold-rolling material and Ti-6Al-4V and INCONEL 718 were selected as typical hot-rolling and cold-rolling alloys, respectively. The flow stress and workability of these alloys were characterized and friction factor at the roll/workpiece interface was determined at their respective working conditions by conducting ring tests. Computer-aided mathematical models for predicting metal flow and stresses, and for simulating the shape-rolling process were developed. These models utilize the upper-bound and the slab methods of analysis, and are capable of predicting the lateral spread, roll-separating force, roll torque and local stresses, strains and strain rates. This computer-aided design (CAD) system is also capable of simulating the actual rolling process and thereby designing roll-pass schedule in rolling of an airfoil or similar shape. The predictions from the CAD system were verified with respect to cold rolling of mild steel plates. The system is being applied to cold and hot isothermal rolling of an airfoil shape, and will be verified with respect to laboratory experiments under controlled conditions.

  20. Arithmetic processing in the brain shaped by cultures

    PubMed Central

    Tang, Yiyuan; Zhang, Wutian; Chen, Kewei; Feng, Shigang; Ji, Ye; Shen, Junxian; Reiman, Eric M.; Liu, Yijun

    2006-01-01

    The universal use of Arabic numbers in mathematics raises a question whether these digits are processed the same way in people speaking various languages, such as Chinese and English, which reflect differences in Eastern and Western cultures. Using functional MRI, we demonstrated a differential cortical representation of numbers between native Chinese and English speakers. Contrasting to native English speakers, who largely employ a language process that relies on the left perisylvian cortices for mental calculation such as a simple addition task, native Chinese speakers, instead, engage a visuo-premotor association network for the same task. Whereas in both groups the inferior parietal cortex was activated by a task for numerical quantity comparison, functional MRI connectivity analyses revealed a functional distinction between Chinese and English groups among the brain networks involved in the task. Our results further indicate that the different biological encoding of numbers may be shaped by visual reading experience during language acquisition and other cultural factors such as mathematics learning strategies and education systems, which cannot be explained completely by the differences in languages per se. PMID:16815966

  1. Invariant visual object recognition and shape processing in rats

    PubMed Central

    Zoccolan, Davide

    2015-01-01

    Invariant visual object recognition is the ability to recognize visual objects despite the vastly different images that each object can project onto the retina during natural vision, depending on its position and size within the visual field, its orientation relative to the viewer, etc. Achieving invariant recognition represents such a formidable computational challenge that is often assumed to be a unique hallmark of primate vision. Historically, this has limited the invasive investigation of its neuronal underpinnings to monkey studies, in spite of the narrow range of experimental approaches that these animal models allow. Meanwhile, rodents have been largely neglected as models of object vision, because of the widespread belief that they are incapable of advanced visual processing. However, the powerful array of experimental tools that have been developed to dissect neuronal circuits in rodents has made these species very attractive to vision scientists too, promoting a new tide of studies that have started to systematically explore visual functions in rats and mice. Rats, in particular, have been the subjects of several behavioral studies, aimed at assessing how advanced object recognition and shape processing is in this species. Here, I review these recent investigations, as well as earlier studies of rat pattern vision, to provide an historical overview and a critical summary of the status of the knowledge about rat object vision. The picture emerging from this survey is very encouraging with regard to the possibility of using rats as complementary models to monkeys in the study of higher-level vision. PMID:25561421

  2. Combining shape and position expectancies: hierarchical processing and selective inhibition.

    PubMed

    Klingstone, A; Klein, R

    1991-05-01

    Two experiments report the effects of generating a concurrent position expectancy and form expectancy. Ss were precued to a stimulus position where 1 target shape was most probable, and they made a speeded 2-choice response to the orientation of the displayed shape. Response time (RT) was faster for an expected position than an unexpected position and faster for a likely shape than for an unlikely shape. This replicates the work of Lambert and Hockey (1986). It was also observed, however, that when a stimulus appeared at an unexpected position where 2 shapes were equally improbable, RT was slower for the shape that had been likely rather than unlikely at the cued position. This finding is incompatible with the probability-matching hypothesis of Lambert and Hockey. The data support a hierarchical-expectancy model of attentional selectivity. PMID:1830089

  3. Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties

    SciTech Connect

    Li Siheng; Wang Enbo Tian Chungui; Mao Baodong; Kang Zhenhui; Li Qiuyu; Sun Guoying

    2008-07-15

    In this paper, a simple strategy is developed for rational fabrication of a class of jingle-bell-shaped hollow structured nanomaterials marked as Ag(MFe{sub 2}O{sub 4}) (M=Ni, Co, Mg, Zn), consisting of ferrite hollow shells and metal nanoparticle cores, using highly uniform colloidal Ag(C) microspheres as template. The final composites were obtained by direct adsorption of metal cations Fe{sup 3+} and M{sup 2+} on the surface of the Ag(C) spheres followed by calcination process to remove the middle carbon shell and transform the metal ions into pure phase ferrites. The as-prepared composites were characterized by X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectroscopy and SQUID magnetometer. The results showed that the composites possess the magnetic property of the ferrite shell and the optical together with antibacterial property of the Ag core. - Graphical abstract: MFe{sub 2}O{sub 4} (M=Ni, Co, Mg, Zn) hollow spheres with a noble metal nanoparticle core were successfully prepared by using colloidal metal(C) core-shell spheres as templates with no need of surface modification. The shell thickness and magnetic properties of the ferrite hollow spheres could be controlled by varying the synthetic parameters.

  4. Revealing the spiral arms through radial migration and the shape of the Metallicity Distribution Function

    NASA Astrophysics Data System (ADS)

    Martinez-Medina, L. A.; Pichardo, B.; Moreno, E.; Peimbert, A.

    2016-08-01

    Recent observations show that the Milky Way's metallicity distribution function (MDF) changes its shape as a function of radius. This new evidence of radial migration within the stellar disc sets additional constraints on Galactic models. By performing controlled test particle simulations in a very detailed, observationally motivated model of the Milky Way, we demonstrate that, in the inner region of the disc, the MDF is shaped by the joint action of the bar and spiral arms, while at outer radii the MDF is mainly shaped by the spiral arms. We show that the spiral arms are able to imprint their signature in the radial migration, shaping the MDF in the outskirts of the Galactic disc with a minimal participation of the bar. Conversely, this work has the potential to characterise some structural and dynamical parameters of the spiral arms based on radial migration and the shape of the MDF. Finally, the resemblance obtained with this approximation to the MDF curves of the Galaxy as seen by APOGEE, show that a fundamental factor influencing their shape is the Galactic potential.

  5. Revealing the spiral arms through radial migration and the shape of the metallicity distribution function

    NASA Astrophysics Data System (ADS)

    Martinez-Medina, L. A.; Pichardo, B.; Moreno, E.; Peimbert, A.

    2016-11-01

    Recent observations show that the Milky Way's metallicity distribution function (MDF) changes its shape as a function of radius. This new evidence of radial migration within the stellar disc sets additional constraints on Galactic models. By performing controlled test particle simulations in a very detailed, observationally motivated model of the Milky Way, we demonstrate that, in the inner region of the disc, the MDF is shaped by the joint action of the bar and spiral arms, while at outer radii the MDF is mainly shaped by the spiral arms. We show that the spiral arms are able to imprint their signature in the radial migration, shaping the MDF in the outskirts of the Galactic disc with a minimal participation of the bar. Conversely, this work has the potential to characterize some structural and dynamical parameters of the spiral arms based on radial migration and the shape of the MDF. Finally, the resemblance obtained with this approximation to the MDF curves of the Galaxy as seen by APOGEE, show that a fundamental factor influencing their shape is the Galactic potential.

  6. Functional Characterization of Shape Memory CuZnAl Open-Cell Foams by Molten Metal Infiltration

    NASA Astrophysics Data System (ADS)

    Arnaboldi, S.; Bassani, P.; Passaretti, F.; Redaelli, A.; Tuissi, A.

    2011-07-01

    In the recent years, the research for novel materials with tailored mechanical properties, as well as functional properties, has encouraged the study of porous and cellular materials. Our previous work proposed and reported about the possibility to manufacture open-cell metal foams of CuZnAl shape memory alloy by liquid infiltration in a leachable bed of silica-gel particles. This innovative methodology is based on cheap commercial consumables and a simple technology, focusing on intermediate-density low-cost foams with interesting cost/benefits ratio. Microstructural analyses on foamed specimens showed uniform microstructure of ligaments and a very regular and well reproducible open-cell morphology. Moreover, calorimetric analysis detected a thermo-elastic martensitic transformation in the foamed material. In this study, a CuZnAl shape memory alloy was considered and tested to clarify possible effects of the foaming process on the functional properties of the material. Morphological, calorimetric, and thermo-mechanical analyses were carried out. The results show that it is possible to produce metal foams of CuZnAl shape memory alloy with different functional properties and able to recover mono-axial compressive strains up to 3%.

  7. Linear and nonlinear second-order polarizabilities of hemispherical and sector-shaped metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Jayabalan, J.; Singh, Manoranjan P.; Banerjee, Arup; Rustagi, K. C.

    2008-01-01

    In this paper, we present results of calculations of linear and second-order nonlinear polarizabilities of sector-shaped metallic nanoparticles (hemisphere is a special case) using free electron theory. The dependences of the ground state electron density distribution and polarizabilities on various shape parameters of sector are analyzed. The ground state electron densities near the corners and edges of sector-shaped nanoparticle are very low and do not contribute to the linear and second-order polarizabilities. The second-order polarizability is found to depend strongly on the angle of the sector and is shown to be proportional to the product of an appropriately defined asymmetric volume of the particle and the third power of the electron cloud length.

  8. Metal-affinity separations: A new dimension in protein processing

    SciTech Connect

    Arnold, F.H. )

    1991-02-01

    Rapid growth in the preparative and high-resolution analytical applications of metal-affinity chromatography demonstrate the appeal of metal recognition as a basis for protein separations. Stable, inexpensive chelated metals effectively mimic biospecific interactions, providing selective ligands for protein binding. This article reviews recent progress in understanding the mechanisms of metal-protein recognition that underlie metal-affinity separations. Also discussed are schemes for integrating metal-affinity purifications into the expression and bioprocessing of recombinant proteins. Promising future developments include new metal-affinity processes for analytical and preparative-scale separations and a range of techniques for enhancing the selectivity of metal-affinity separations.

  9. Investigation of the laser engineered net shaping process for nanostructured cermets

    NASA Astrophysics Data System (ADS)

    Xiong, Yuhong

    Laser Engineered Net Shaping (LENSRTM) is a solid freeform fabrication (SFF) technology that combines high power laser deposition and powder metallurgy technologies. The LENSRTM technology has been used to fabricate a number of metallic alloys with improved physical and mechanical material properties. The successful application provides a motivation to also apply this method to fabricate non-metallic alloys, such as tungsten carbide-cobalt (WC-Co) cermets in a timely and easy way. However, reports on this topic are very limited. In this work, the LENSRTM technology was used to investigate its application to nanostructured WC-Co cermets, including processing conditions, microstructural evolution, thermal behavior, mechanical properties, and environmental and economic benefits. Details of the approaches are described as follows. A comprehensive analysis of the relationships between process parameters, microstructural evolution and mechanical properties was conducted through various analytical techniques. Effects of process parameters on sample profiles and microstructures were analyzed. Dissolution, shape change and coarsening of WC particles were investigated to study the mechanisms of microstructural evolution. The thermal features were correlated with the microstructure and mechanical properties. The special thermal behavior during this process and its relevant effects on the microstructure have been experimentally studied and numerically simulated. A high-speed digital camera was applied to study the temperature profile, temperature gradient and cooling rate in and near the molten pool. Numerical modeling was employed for 3D samples using finite element method with ADINA software for the first time. The validated modeling results were used to interpret microstructural evolution and thermal history. In order to fully evaluate the capability of the LENSRTM technology for the fabrication of cermets, material properties of WC-Co cermets produced by different powder

  10. Metallic Recovery and Ferrous Melting Processes

    SciTech Connect

    Luis Trueba

    2004-05-30

    The effects of melting atmosphere and charge material type on the metallic and alloy recovery of ferrous charge materials were investigated in two sets of experiments (Tasks 1 and 2). In addition, thermodynamic studies were performed (Task 3) to determine the suitability of ladle treatment for the production of ductile iron using scrap charge materials high in manganese and sulfur. Task 1--In the first set of experiments, the charge materials investigated were thin steel scrap, thick steel scrap, cast iron scrap, and pig iron in the rusty and clean states. Melting atmospheres in this set of experiments were varied by melting with and without a furnace cover. In this study, it was found that neither covered melting nor melting clean (non-rusty) ferrous charge materials improved the metallic recovery over the recovery experienced with uncovered melting or rusty charge materials. However, the silicon and manganese recoveries were greater with covered melting and clean materials. Silicon and manganese in the molten iron react with oxygen dissolved in the iron from uncovered melting and oxidized iron (surface rust). Silica and manganese silicates are formed which float to the slag decreasing recoveries of silicon and manganese. Cast iron and pig iron had higher metallic recoveries than steel scrap. Carbon recovery was affected by the carbon content of the charge materials, and not by the melting conditions. Irons with higher silicon contents had higher silicon recovery than irons with lower silicon contents. Task 2--In the second set of experiments, briquetted turnings and borings were used to evaluate the effects of briquette cleanliness, carbon additions, and melting atmosphere on metallic and alloy recovery. The melting atmosphere in this set of experiments was varied by melting in air and with an argon atmosphere using the SPAL process. In this set of experiments, carbon additions to the briquettes were found to have the greatest effect on metallic and alloy

  11. Enhanced optical transmission by V-shaped nanoslit in metal film

    NASA Astrophysics Data System (ADS)

    He, Meng-Dong; Ma, Wang-Guo; Wang, Xin-Jun

    2013-11-01

    In this paper, we reveal that the enhanced transmission through a perforated metal film can be further boosted up by a V-shaped nanoslit, which consists of two connected oblique slits. The maximum transmission at resonance can be enhanced significantly by 71.5% in comparison with the corresponding vertical slit with the same exit width. The value and position of transmission resonance peak strongly depend on the apex angle of the V-shaped slit. The optimum apex angle, at which the transmission is maximal, is sensitive to the slit width. Such phenomena can be well explained by a concrete picture in which the incident wave drives free electrons on the slit walls. Moreover, we also simply analyze the splitting of the transmission peak in the symmetry broken V-shaped slit, originating from the resonances of different parts of the V-shaped slit. We expect that our findings will be used to design the nanoscale light sources based on the metal nanoslit structures.

  12. Mechanical properties of Ti-6Al-4V specimens produced by shaped metal deposition

    NASA Astrophysics Data System (ADS)

    Baufeld, Bernd; van der Biest, Omer

    2009-01-01

    Shaped metal deposition is a novel technique to build near net-shape components layer by layer by tungsten inert gas welding. Especially for complex shapes and small quantities, this technique can significantly lower the production cost of components by reducing the buy-to-fly ratio and lead time for production, diminishing final machining and preventing scrap. Tensile testing of Ti-6Al-4V components fabricated by shaped metal deposition shows that the mechanical properties are competitive to material fabricated by conventional techniques. The ultimate tensile strength is between 936 and 1014 MPa, depending on the orientation and location. Tensile testing vertical to the deposition layers reveals ductility between 14 and 21%, whereas testing parallel to the layers gives a ductility between 6 and 11%. Ultimate tensile strength and ductility are inversely related. Heat treatment within the α+β phase field does not change the mechanical properties, but heat treatment within the β phase field increases the ultimate tensile strength and decreases the ductility. The differences in ultimate tensile strength and ductility can be related to the α lath size and orientation of the elongated, prior β grains. The micro-hardness and Young's modulus are similar to conventional Ti-6Al-4V with low oxygen content.

  13. Process for fabrication of metal oxide films

    SciTech Connect

    Tracy, C.E.; Benson, D.; Svensson, S.

    1990-07-17

    This invention is comprised of a method of fabricating metal oxide films from a plurality of reactants by inducing a reaction by plasma deposition among the reactants. The plasma reaction is effective for consolidating the reactants and producing thin films of metal oxides, e.g. electro-optically active transition metal oxides, at a high deposition rate. The presence of hydrogen during the plasma reaction enhances the deposition rate of the metal oxide. Various types of metal oxide films can be produced.

  14. Low-loss light transmission in a rectangular-shaped hybrid metal trench at 1550 nm.

    PubMed

    Yang, Pengfei; Di, Zhigang; Xu, Hongxing

    2013-07-15

    A hybrid plasmonic waveguide consisting of a high-index dielectric core embedded inside a rectangular-shaped metallic trench is proposed and its guiding properties are investigated at the wavelength of 1550 nm. Numerical simulations based on the finite element method have demonstrated that the introduced dielectric core could greatly reduce the modal loss of the metal trench while maintaining strong confinement of light. The effects of dielectric core size, material of the cladding and the dielectric core on the modal properties have been systematically investigated. The proposed hybrid plasmonic structure can be realized employing fabrication techniques of the traditional metal trench waveguides and could be leveraged as important elements for highly-integrated photonic circuits.

  15. Slip casting and extruding shapes of rhenium with metal oxide additives. 1: Feasibility demonstration

    NASA Technical Reports Server (NTRS)

    Barr, F. A.; Page, R. J.

    1986-01-01

    The feasibility of fabricating small rhenium parts with metal oxide additives by means of slip casting and extrusion techniques is described. The metal oxides, ZrO2 and HfO2 were stabilized into the cubic phase with Y2O3. Additions of metal oxide to the rhenium of up to 15 weight percent were used. Tubes of 17 mm diameter with 0.5 mm walls were slip cast by adapting current ceramic oxide techniques. A complete cast double conical nozzle demonstrated the ability to meet shapes and tolerances. Extrusion of meter long tubing lengths of 3.9 mm o.d. x 2.3 mm i.d. final dimension is documented. Sintering schedules are presented to produce better than 95% of theoretical density parts. Finished machining was found possible were requried by electric discharge machining and diamond grinding.

  16. Laser Processing of Metals and Polymers

    SciTech Connect

    Singaravelu, Senthilraja

    2012-05-01

    A laser offers a unique set of opportunities for precise delivery of high quality coherent energy. This energy can be tailored to alter the properties of material allowing a very flexible adjustment of the interaction that can lead to melting, vaporization, or just surface modification. Nowadays laser systems can be found in nearly all branches of research and industry for numerous applications. Sufficient evidence exists in the literature to suggest that further advancements in the field of laser material processing will rely significantly on the development of new process schemes. As a result they can be applied in various applications starting from fundamental research on systems, materials and processes performed on a scientific and technical basis for the industrial needs. The interaction of intense laser radiation with solid surfaces has extensively been studied for many years, in part, for development of possible applications. In this thesis, I present several applications of laser processing of metals and polymers including polishing niobium surface, producing a superconducting phase niobium nitride and depositing thin films of niobium nitride and organic material (cyclic olefin copolymer). The treated materials were examined by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), atomic force microscopy (AFM), high resolution optical microscopy, surface profilometry, Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD). Power spectral density (PSD) spectra computed from AFM data gives further insight into the effect of laser melting on the topography of the treated niobium.

  17. Shape 4.0: 3D Shape Modeling and Processing Using Semantics.

    PubMed

    Spagnuolo, Michela

    2016-01-01

    In the last decade, sensor, communication, and computing technologies have advanced rapidly, producing dramatic changes in our daily lives and in a variety of application domains. Emerging technologies are leading us to a gradual, but inescapable integration of our material and digital realities and the advent of cyber-physical worlds. Although attaining visual realism is within the grasp of current 3D modeling approaches, it is less clear whether current modeling techniques will accommodate the needs of human communication and of the applications that we can already envisage in those futuristic worlds. Inspired by the evolution trends of the Web, this article describes the evolution of shape modeling from the Shape 1.0 geometry-only, mesh-based stage to the forthcoming semantics-driven Shape 4.0 era. PMID:26780764

  18. Shape 4.0: 3D Shape Modeling and Processing Using Semantics.

    PubMed

    Spagnuolo, Michela

    2016-01-01

    In the last decade, sensor, communication, and computing technologies have advanced rapidly, producing dramatic changes in our daily lives and in a variety of application domains. Emerging technologies are leading us to a gradual, but inescapable integration of our material and digital realities and the advent of cyber-physical worlds. Although attaining visual realism is within the grasp of current 3D modeling approaches, it is less clear whether current modeling techniques will accommodate the needs of human communication and of the applications that we can already envisage in those futuristic worlds. Inspired by the evolution trends of the Web, this article describes the evolution of shape modeling from the Shape 1.0 geometry-only, mesh-based stage to the forthcoming semantics-driven Shape 4.0 era.

  19. Optimization of Forming Processes with Different Sheet Metal Alloys

    NASA Astrophysics Data System (ADS)

    Sousa, Luísa C.; Castro, Catarina F.; António, Carlos C.

    2007-05-01

    Over the past decades relatively heavy components made of steel alloys comprise the majority of many manufactured parts due to steel's low cost, high formability and good strength. The desire to produce lightweight parts has led to studies searching for lighter and stronger materials such as aluminum alloys. However, they exhibit lower elastic stiffness than steel resulting in higher elastic strains causing known distortions such as spring-back and so decreasing accuracy of manufactured net-shape components. This paper presents a developed computational method to optimize the design of sheet metal processes using genetic algorithms. An inverse approach is considered so that the final geometry of the bended blank closely follows a prescribed one. The developed computational method couples a finite element forming simulation and an evolutionary algorithm searching the optimal design parameters of the process. The developed method searches the optimal parameters that ensure a perfect net-shape part. Different aluminum alloys candidates for automotive structural applications are considered and the optimal solutions are analyzed.

  20. Optimization of Forming Processes with Different Sheet Metal Alloys

    SciTech Connect

    Sousa, Luisa C.; Castro, Catarina F.; Antonio, Carlos C.

    2007-05-17

    Over the past decades relatively heavy components made of steel alloys comprise the majority of many manufactured parts due to steel's low cost, high formability and good strength. The desire to produce lightweight parts has led to studies searching for lighter and stronger materials such as aluminum alloys. However, they exhibit lower elastic stiffness than steel resulting in higher elastic strains causing known distortions such as spring-back and so decreasing accuracy of manufactured net-shape components. This paper presents a developed computational method to optimize the design of sheet metal processes using genetic algorithms. An inverse approach is considered so that the final geometry of the bended blank closely follows a prescribed one. The developed computational method couples a finite element forming simulation and an evolutionary algorithm searching the optimal design parameters of the process. The developed method searches the optimal parameters that ensure a perfect net-shape part. Different aluminum alloys candidates for automotive structural applications are considered and the optimal solutions are analyzed.

  1. Catalytic extraction processing of contaminated scrap metal

    SciTech Connect

    Griffin, T.P.; Johnston, J.E.; Payea, B.M.

    1995-10-01

    The U.S. Department of Energy issued a Planned Research and Development Announcement (PRDA) in 1993, with the objective of identifying unique technologies which could be applied to the most hazardous waste streams at DOE sites. The combination of radioactive contamination with additional contamination by hazardous constituents such as those identified by the Resource Conservation and Recovery Act (RCRA) pose an especially challenging problem. Traditional remediation technologies are increasingly becoming less acceptable to stakeholders and regulators because of the risks they pose to public health and safety. Desirable recycling technologies were described by the DOE as: (1) easily installed, operated, and maintained; (2) exhibiting superior environmental performance; (3) protective of worker and public health and safety; (4) readily acceptable to a wide spectrum of evaluators; and (5) economically feasible. Molten Metal Technology, Inc. (MMT) was awarded a contract as a result of the PRDA initiative to demonstrate the applicability of Catalytic Extraction Processing (CEP), MMT`s proprietary elemental recycling technology, to DOE`s inventory of low level mixed waste. This includes DOE`s inventory of radioactively- and RCRA-contaminated scrap metal and other waste forms expected to be generated by the decontamination and decommissioning (D&D) of DOE sites.

  2. Anisotropic porous metals production by melt processing

    SciTech Connect

    Shapovalov, V.; Boiko, L.; Baldwin, M.D.; Maguire, M.C.; Zanner, F.J.

    1997-02-01

    The collapse of the Soviet Union has left many of its scientific institutes and technical universities without their traditional backbone of financial support. In an effort to stem the export of science to nations advocating nuclear proliferation, and to acquire potentially useful technology, several US government-sponsored programs have arise to mine the best of former USSR scientific advances. In the field of metallurgy, the earliest institutes to be investigated by Sandia National Laboratories are located in Ukraine. In particular, scientists at the State Metallurgical Academy have developed unique porous metals, resembling what could be described as gas-solid ``eutectic``. While porous metals are available in the US and other western countries, none have the remarkable structure and properties of these materials. Sandia began a collaborative program with the Ukrainian scientists to bring this technology to the US, verify the claims regarding these materials, and begin production of the so-called Gasars. This paper will describe the casting process technology and metallurgy associated with the production of Gasars, and will review the progress of the collaborative project.

  3. Analysis of electromagnetic scattering from irregularly shaped, thin, metallic flat plates

    NASA Technical Reports Server (NTRS)

    Deshpande, Manohar D.; Cockrell, C. R.; Beck, Fred B.; Vedeler, Erik; Koch, Melissa B.

    1993-01-01

    This report describes an application of the method of moments to calculate the electromagnetic scattering from irregularly shaped, thin, metallic flat plates in free space. In the present technique, an irregularly shaped plate is enclosed by a rectangle on which the surface-current density is then expressed in terms of subdomain functions by dividing the rectangle into subsections. A shape function is introduced to ensure zero current outside the patch. The surface-current density is determined using the electric field integral equation (EFIE) approach in conjunction with the method of moments, and from a knowledge of the surface-current density, the electromagnetic scattering from a plate is calculated. Using this technique, the electromagnetic scattering from a hexagonal plate; an equilateral triangular plate; an equilateral triangular plate with a concentric, equilateral triangular hole and an inverted, equilateral triangular hole; and a diamond-shaped plate is computed and compared with the numerical results obtained by using the Electromagnetic Surface Patch (ESP) code developed by Ohio State University. The numerical results compare favorably with the measurements performed on these shapes in the Langley Experimental Test Range facility.

  4. Nonlinear computations shaping temporal processing of precortical vision.

    PubMed

    Butts, Daniel A; Cui, Yuwei; Casti, Alexander R R

    2016-09-01

    Computations performed by the visual pathway are constructed by neural circuits distributed over multiple stages of processing, and thus it is challenging to determine how different stages contribute on the basis of recordings from single areas. In the current article, we address this problem in the lateral geniculate nucleus (LGN), using experiments combined with nonlinear modeling capable of isolating various circuit contributions. We recorded cat LGN neurons presented with temporally modulated spots of various sizes, which drove temporally precise LGN responses. We utilized simultaneously recorded S-potentials, corresponding to the primary retinal ganglion cell (RGC) input to each LGN cell, to distinguish the computations underlying temporal precision in the retina from those in the LGN. Nonlinear models with excitatory and delayed suppressive terms were sufficient to explain temporal precision in the LGN, and we found that models of the S-potentials were nearly identical, although with a lower threshold. To determine whether additional influences shaped the response at the level of the LGN, we extended this model to use the S-potential input in combination with stimulus-driven terms to predict the LGN response. We found that the S-potential input "explained away" the major excitatory and delayed suppressive terms responsible for temporal patterning of LGN spike trains but revealed additional contributions, largely PULL suppression, to the LGN response. Using this novel combination of recordings and modeling, we were thus able to dissect multiple circuit contributions to LGN temporal responses across retina and LGN, and set the foundation for targeted study of each stage. PMID:27334959

  5. The s-process at low metallicity

    NASA Astrophysics Data System (ADS)

    Stancliffe, Richard J.; Lugaro, Maria A.; Karakas, Amanda I.; Rijs, Carlos

    2012-09-01

    We present models for the slow neutron-capture process (s-process) in asymptotic giant branch stars of metallicity [Fe/H] = -2.3 and masses 0.9 - 6Msolar. The models where the 13C burns radiatively (stars of around 2Msolar) produce an overall good match to carbon-enhanced metalpoor (CEMP) stars showing barium enhancements (CEMP-s). On the other hand, none of our models can provide a match to the composition of CEMP stars showing both barium and europium enhancements (CEMP-s/r). The models fail to reproduce the observed Eu abundances, and they also fail to reproduce the correlation between the Eu and Ba abundances. They also cannot match the ratio of heavy-to-light s-process elements observed in many CEMP-s/r stars, which can be more than 10 times higher than in the Solar System. This work has been published [1] and the interested reader should refer to that work for further details, included published tables of yields.

  6. Process for removing technetium from iron and other metals

    DOEpatents

    Leitnaker, James M.; Trowbridge, Lee D.

    1999-01-01

    A process for removing technetium from iron and other metals comprises the steps of converting the molten, alloyed technetium to a sulfide dissolved in manganese sulfide, and removing the sulfide from the molten metal as a slag.

  7. Process for removing technetium from iron and other metals

    DOEpatents

    Leitnaker, J.M.; Trowbridge, L.D.

    1999-03-23

    A process for removing technetium from iron and other metals comprises the steps of converting the molten, alloyed technetium to a sulfide dissolved in manganese sulfide, and removing the sulfide from the molten metal as a slag. 4 figs.

  8. Facile 3D Metal Electrode Fabrication for Energy Applications via Inkjet Printing and Shape Memory Polymer

    NASA Astrophysics Data System (ADS)

    Roberts, R. C.; Wu, J.; Hau, N. Y.; Chang, Y. H.; Feng, S. P.; Li, D. C.

    2014-11-01

    This paper reports on a simple 3D metal electrode fabrication technique via inkjet printing onto a thermally contracting shape memory polymer (SMP) substrate. Inkjet printing allows for the direct patterning of structures from metal nanoparticle bearing liquid inks. After deposition, these inks require thermal curing steps to render a stable conductive film. By printing onto a SMP substrate, the metal nanoparticle ink can be cured and substrate shrunk simultaneously to create 3D metal microstructures, forming a large surface area topology well suited for energy applications. Polystyrene SMP shrinkage was characterized in a laboratory oven from 150-240°C, resulting in a size reduction of 1.97-2.58. Silver nanoparticle ink was patterned into electrodes, shrunk, and the topology characterized using scanning electron microscopy. Zinc-Silver Oxide microbatteries were fabricated to demonstrate the 3D electrodes compared to planar references. Characterization was performed using 10M potassium hydroxide electrolyte solution doped with zinc oxide (57g/L). After a 300s oxidation at 3Vdc, the 3D electrode battery demonstrated a 125% increased capacity over the reference cell. Reference cells degraded with longer oxidations, but the 3D electrodes were fully oxidized for 4 hours, and exhibited a capacity of 5.5mA-hr/cm2 with stable metal performance.

  9. Optical filtering properties of subwavelength Tai-chi-shaped metal hole arrays

    NASA Astrophysics Data System (ADS)

    Wang, Xinlin; Liu, Hui; Luo, Hu; Zhu, Weihua; Chen, Zhiyong; Liu, Jun; Guo, Wei

    2015-04-01

    Finite-difference time-domain (FDTD) method is employed to study the optical properties of a novel kind of periodic subwavelength hole arrays composed of Tai-chi-shaped holes in silver film, and the optical transmission properties of femtosecond optical pulse excitation is numerically calculated. We find that this Tai-chi-shaped device has better optical band-pass filtering properties, such as narrower pass band and higher transmissivity in visible wavelengths range, than other devices under consideration. Based on the generation of surface plasmons resonance mode in the dielectric-metal interface, the center wavelength of transmission can be tuned by changing the array periodicities. We observe that the tune ability mainly depends on the space period along the direction parallel to that of the incident pulse polarization. It is also found that both the strength and the wavelength of the transmission peaks of rectangularly distributed metal hole arrays are determined by the polarization of incident light. Additionally, we demonstrate the typical band-pass filtering properties of this Tai-Chi-shaped holes structure. The full-width at half-maximum (FWHM) of the narrow pass band is about 20 nm in visible wavelengths range.

  10. Responsive nanoporous metals: recoverable modulations on strength and shape by watering.

    PubMed

    Ye, Xing-Long; Liu, Ling-Zhi; Jin, Hai-Jun

    2016-08-12

    Many biological materials can readily modulate their mechanical properties and shape by interacting with water in the surrounding environment, which is essential to their high performance in application. In contrast, typical inorganic materials (such as the metals) cannot change their strength and shape without involving thermal/mechanical treatments. By introducing nano-scale porous structure and exploiting a simple physical concept-the water-capillarity in nanopores, here we report that a 'dead' metal can be transformed into a 'smart' material with water-responsive properties. We demonstrate that the apparent strength, volume and shape of nanoporous Au and Au(Pt) can be modulated in situ, dramatically and recoverably, in response to water-dipping and partial-drying. The amplitude of strength-modulation reaches 20 MPa, which is nearly 50% of the yield strength at initial state. This approach also leads to reversible length change up to 1.3% in nanoporous Au and a large reversible bending motion of a bi-layer strip with tip displacement of ∼20 mm, which may be used for actuation. This method is simple and effective, occurring in situ under ambient conditions and requiring no external power, analogous to biological materials. The findings may open up novel applications in many areas such as micro-robotics and bio-medical devices. PMID:27347850

  11. Responsive nanoporous metals: recoverable modulations on strength and shape by watering

    NASA Astrophysics Data System (ADS)

    Ye, Xing-Long; Liu, Ling-Zhi; Jin, Hai-Jun

    2016-08-01

    Many biological materials can readily modulate their mechanical properties and shape by interacting with water in the surrounding environment, which is essential to their high performance in application. In contrast, typical inorganic materials (such as the metals) cannot change their strength and shape without involving thermal/mechanical treatments. By introducing nano-scale porous structure and exploiting a simple physical concept—the water-capillarity in nanopores, here we report that a ‘dead’ metal can be transformed into a ‘smart’ material with water-responsive properties. We demonstrate that the apparent strength, volume and shape of nanoporous Au and Au(Pt) can be modulated in situ, dramatically and recoverably, in response to water-dipping and partial-drying. The amplitude of strength-modulation reaches 20 MPa, which is nearly 50% of the yield strength at initial state. This approach also leads to reversible length change up to 1.3% in nanoporous Au and a large reversible bending motion of a bi-layer strip with tip displacement of ∼20 mm, which may be used for actuation. This method is simple and effective, occurring in situ under ambient conditions and requiring no external power, analogous to biological materials. The findings may open up novel applications in many areas such as micro-robotics and bio-medical devices.

  12. Induction slag reduction process for purifying metals

    DOEpatents

    Traut, Davis E.; Fisher, II, George T.; Hansen, Dennis A.

    1991-01-01

    A continuous method is provided for purifying and recovering transition metals such as neodymium and zirconium that become reactive at temperatures above about 500.degree. C. that comprises the steps of contacting the metal ore with an appropriate fluorinating agent such as an alkaline earth metal fluosilicate to form a fluometallic compound, and reducing the fluometallic compound with a suitable alkaline earth or alkali metal compound under molten conditions, such as provided in an induction slag metal furnace. The method of the invention is advantageous in that it is simpler and less expensive than methods used previously to recover pure metals, and it may be employed with a wide range of transition metals that were reactive with enclosures used in the prior art methods and were hard to obtain in uncontaminated form.

  13. Process for the enhanced capture of heavy metal emissions

    DOEpatents

    Biswas, Pratim; Wu, Chang-Yu

    2001-01-01

    This invention is directed to a process for forming a sorbent-metal complex. The process includes oxidizing a sorbent precursor and contacting the sorbent precursor with a metallic species. The process further includes chemically reacting the sorbent precursor and the metallic species, thereby forming a sorbent-metal complex. In one particular aspect of the invention, at least a portion of the sorbent precursor is transformed into sorbent particles during the oxidation step. These sorbent particles then are contacted with the metallic species and chemically reacted with the metallic species, thereby forming a sorbent-metal complex. Another aspect of the invention is directed to a process for forming a sorbent metal complex in a combustion system. The process includes introducing a sorbent precursor into a combustion system and subjecting the sorbent precursor to an elevated temperature sufficient to oxidize the sorbent precursor and transform the sorbent precursor into sorbent particles. The process further includes contacting the sorbent particles with a metallic species and exposing the sorbent particles and the metallic species to a complex-forming temperature whereby the metallic species reacts with the sorbent particles thereby forming a sorbent-metal complex under UV irradiation.

  14. Metal induced self-assembly of designed V-shape protein into 2D wavy supramolecular nanostructure

    NASA Astrophysics Data System (ADS)

    Qiao, S. P.; Lang, C.; Wang, R. D.; Li, X. M.; Yan, T. F.; Pan, T. Z.; Zhao, L. L.; Fan, X. T.; Zhang, X.; Hou, C. X.; Luo, Q.; Xu, J. Y.; Liu, J. Q.

    2015-12-01

    In order to understand and imitate the more complex bio-processes and fascinating functions in nature, protein self-assembly has been studied and has attracted more and more interest in recent years. Artificial self-assemblies of proteins have been constructed through many strategies. However, the design of complicated protein self-assemblies utilizing the special profile of building blocks remains a challenge. We herein report linear and 2D nanostructures constructed from a V shape SMAC protein and induced by metal coordination. Zigzag nanowires and wavy 2D nanostructures have been demonstrated by AFM and TEM. The zigzag nanowires can translate to a 2D nanostructure with an excess of metal ions, which reveals the step by step assembly process. Fluorescence and UV/Vis spectra have also been obtained to further study the mechanism and process of self-assembly. Upon the protein nanostructure, fluorescence resonance energy transfer (FRET) could also be detected using fluorescein modified proteins as building blocks. This article provides an approach for designing and controlling self-assembled protein nanostructures with a distinctive topological morphology.In order to understand and imitate the more complex bio-processes and fascinating functions in nature, protein self-assembly has been studied and has attracted more and more interest in recent years. Artificial self-assemblies of proteins have been constructed through many strategies. However, the design of complicated protein self-assemblies utilizing the special profile of building blocks remains a challenge. We herein report linear and 2D nanostructures constructed from a V shape SMAC protein and induced by metal coordination. Zigzag nanowires and wavy 2D nanostructures have been demonstrated by AFM and TEM. The zigzag nanowires can translate to a 2D nanostructure with an excess of metal ions, which reveals the step by step assembly process. Fluorescence and UV/Vis spectra have also been obtained to further

  15. Process for removing cadmium from scrap metal

    DOEpatents

    Kronberg, J.W.

    1995-04-11

    A process is described for the recovery of a metal, in particular, cadmium contained in scrap, in a stable form. The process comprises the steps of mixing the cadmium-containing scrap with an ammonium carbonate solution, preferably at least a stoichiometric amount of ammonium carbonate, and/or free ammonia, and an oxidizing agent to form a first mixture so that the cadmium will react with the ammonium carbonate to form a water-soluble ammine complex; evaporating the first mixture so that ammine complex dissociates from the first mixture leaving carbonate ions to react with the cadmium and form a second mixture that includes cadmium carbonate; optionally adding water to the second mixture to form a third mixture; adjusting the pH of the third mixture to the acid range whereby the cadmium carbonate will dissolve; and adding at least a stoichiometric amount of sulfide, preferably in the form of hydrogen sulfide or an aqueous ammonium sulfide solution, to the third mixture to precipitate cadmium sulfide. This mixture of sulfide is then preferably digested by heating to facilitate precipitation of large particles of cadmium sulfide. The scrap may be divided by shredding or breaking up to expose additional surface area. Finally, the precipitated cadmium sulfide can be mixed with glass formers and vitrified for permanent disposal. 2 figures.

  16. Process for removing cadmium from scrap metal

    DOEpatents

    Kronberg, James W.

    1995-01-01

    A process for the recovery of a metal, in particular, cadmium contained in scrap, in a stable form. The process comprises the steps of mixing the cadmium-containing scrap with an ammonium carbonate solution, preferably at least a stoichiometric amount of ammonium carbonate, and/or free ammonia, and an oxidizing agent to form a first mixture so that the cadmium will react with the ammonium carbonate to form a water-soluble ammine complex; evaporating the first mixture so that ammine complex dissociates from the first mixture leaving carbonate ions to react with the cadmium and form a second mixture that includes cadmium carbonate; optionally adding water to the second mixture to form a third mixture; adjusting the pH of the third mixture to the acid range whereby the cadmium carbonate will dissolve; and adding at least a stoichiometric amount of sulfide, preferably in the form of hydrogen sulfide or an aqueous ammonium sulfide solution, to the third mixture to precipitate cadmium sulfide. This mixture of sulfide is then preferably digested by heating to facilitate precipitation of large particles of cadmium sulfide. The scrap may be divided by shredding or breaking up to expose additional surface area. Finally, the precipitated cadmium sulfide can be mixed with glass formers and vitrified for permanent disposal.

  17. Process for removing cadmium from scrap metal

    DOEpatents

    Kronberg, J.W.

    1994-01-01

    A process for the recovery of a metal, in particular, cadmium contained in scrap, in a stable form. The process comprises the steps of mixing the cadmium-containing scrap with an ammonium carbonate solution, preferably at least a stoichiometric amount of ammonium carbonate, and/or free ammonia, and an oxidizing agent to form a first mixture so that the cadmium will react with the ammonium carbonate to form a water-soluble ammine complex; evaporating the first mixture so that ammine complex dissociates from the first mixture leaving carbonate ions to react with the cadmium and form a second mixture that includes cadmium carbonate; optionally adding water to the second mixture to form a third mixture; adjusting the pH of the third mixture to the acid range whereby the cadmium carbonate will dissolve; and adding at least a stoichiometric amount of sulfide, preferably in the form of hydrogen sulfide or an aqueous ammonium sulfide solution, to the third mixture to precipitate cadmium sulfide. This mixture of sulfide is then preferably digested by heating to facilitate precipitation of large particles of cadmium sulfide. The scrap may be divided by shredding or breaking up to exposure additional surface area. Finally, the precipitated cadmium sulfide can be mixed with glass formers and vitrified for permanent disposal.

  18. A study of shape optimization on the metallic nanoparticles for thin-film solar cells

    PubMed Central

    2013-01-01

    The shape of metallic nanoparticles used to enhance the performance of thin-film solar cells is described by Gielis' superformula and optimized by an evolutionary algorithm. As a result, we have found a lens-like nanoparticle capable of improving the short circuit current density to 19.93 mA/cm2. Compared with a two-scale nanospherical configuration recently reported to synthesize the merits of large and small spheres into a single structure, the optimized nanoparticle enables the solar cell to achieve a further 7.75% improvement in the current density and is much more fabrication friendly due to its simple shape and tolerance to geometrical distortions. PMID:24168131

  19. Mechanical Properties of INCONEL 718 Parts Manufactured by Shaped Metal Deposition (SMD)

    NASA Astrophysics Data System (ADS)

    Baufeld, Bernd

    2012-07-01

    INCONEL 718 parts have been manufactured by shaped metal deposition (SMD), an additive layer manufacturing technique applying wire-based tungsten inert gas welding. This technique is aimed toward mass customization of parts, omitting time- and scrap-intensive, subtractive fabrication routes. SMD results in dense, "near net-shaped" parts without pores, cracks, or fissures. The microstructure of the SMD parts exhibit large, columnar grains with a fine dendritic microstructure. The interdendritic boundaries are decorated by small Laves phase precipitates and by MC carbides. Tensile tests were performed with different strain rates (10-4, 10-3, and 2 × 10-3 1/s), but no dependency on strength or strain at failure was observed. The ultimate tensile strength was 828 ± 8 MPa, the true plastic strain at failure 28 ± 2%, the micro Vickers hardness 266 ± 21 HV200, and the dynamically measured Young's module was 154 ± 1 GPa.

  20. Visual and Haptic Shape Processing in the Human Brain: Unisensory Processing, Multisensory Convergence, and Top-Down Influences.

    PubMed

    Lee Masson, Haemy; Bulthé, Jessica; Op de Beeck, Hans P; Wallraven, Christian

    2016-08-01

    Humans are highly adept at multisensory processing of object shape in both vision and touch. Previous studies have mostly focused on where visually perceived object-shape information can be decoded, with haptic shape processing receiving less attention. Here, we investigate visuo-haptic shape processing in the human brain using multivoxel correlation analyses. Importantly, we use tangible, parametrically defined novel objects as stimuli. Two groups of participants first performed either a visual or haptic similarity-judgment task. The resulting perceptual object-shape spaces were highly similar and matched the physical parameter space. In a subsequent fMRI experiment, objects were first compared within the learned modality and then in the other modality in a one-back task. When correlating neural similarity spaces with perceptual spaces, visually perceived shape was decoded well in the occipital lobe along with the ventral pathway, whereas haptically perceived shape information was mainly found in the parietal lobe, including frontal cortex. Interestingly, ventrolateral occipito-temporal cortex decoded shape in both modalities, highlighting this as an area capable of detailed visuo-haptic shape processing. Finally, we found haptic shape representations in early visual cortex (in the absence of visual input), when participants switched from visual to haptic exploration, suggesting top-down involvement of visual imagery on haptic shape processing. PMID:26223258

  1. Modeling the flow of liquid-metal coolant in the T-shaped mixer

    NASA Astrophysics Data System (ADS)

    Kashinsky, O. N.; Lobanov, P. D.; Kurdyumov, A. S.; Pribaturin, N. A.

    2016-05-01

    The results of experimental studies on the structure of the temperature field in the tube cross section at the flow of liquid-metal coolant in a T-shaped mixer are presented. Experiments were carried out using the Rose alloy as the working fluid. To determine temperature distribution on the test section wall, infrared thermography was used; to determine temperature distribution in the channel cross section, a mobile thermocouple was used. Considerable temperature maldistribution in the mixing zone of liquid flows with different temperatures on the tube wall and in the coolant melt is shown.

  2. Influence of pore and strut shape on open cell metal foam bulk properties

    NASA Astrophysics Data System (ADS)

    Kumar, Prashant; Hugo, Jean-Michel; Topin, Frederic; Vicente, Jerome

    2012-05-01

    The thermo-physical behavior of open-celled metal foams depends on their microscopic structure. An ideal periodic isotropic structure of tetrakaidecahedron shape i.e. Kelvin cell is studied. We have proposed an analytical model in order to obtain geometrical parameters correctly as they have substantial influence on thermal and hydraulic phenomena, where strut geometry is of prime importance. Various relationships between different geometrical parameters and porosities are presented. Consequently, empirical correlations are proposed to determine permeability and inertia coefficient using Ergun like model for computing pressure drop.

  3. Coupling of metals and biominerals: characterizing the interface between ferromagnetic shape-memory alloys and hydroxyapatite.

    PubMed

    Allenstein, Uta; Selle, Susanne; Tadsen, Meike; Patzig, Christian; Höche, Thomas; Zink, Mareike; Mayr, Stefan G

    2015-07-22

    Durable, mechanically robust osseointegration of metal implants poses one of the largest challenges in contemporary orthopedics. The application of biomimetic hydroxyapatite (HAp) coatings as mediators for enhanced mechanical coupling to natural bone constitutes a promising approach. Motivated by recent advances in the field of smart metals that might open the venue for alternate therapeutic concepts, we explore their mechanical coupling to sputter-deposited HAp layers in a combined experimental-theoretical study. While experimental delamination tests and comprehensive structural characterization, including high-resolution transmission electron microscopy, are utilized to establish structure-property relationships, density functional theory based total energy calculations unravel the underlying physics and chemistry of bonding and confirm the experimental findings. Experiments and modeling indicate that sputter-deposited HAp coatings are strongly adherent to the exemplary ferromagnetic shape-memory alloys, Ni-Mn-Ga and Fe-Pd, with delamination stresses and interface bonding strength exceeding the physiological scales by orders of magnitude.

  4. Analysis of Multi-step Forming of Metallic Bipolar Plate for MCFC Using Various Shapes of Preforms

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Hwan; Ryu, Seung-Min; Yang, Dong-Yol; Kang, Dong-Woo; Chang, In-Gab; Lee, Tae-Won

    2010-06-01

    The metallic bipolar plates of a molten carbonate fuel cell (MCFC) consist of a shielded slot plate and a center plate. Among these, the shielded slot plate (the current collector) supports the Membrane Electrode Assembly (MEA) mechanically. The anode gases and the cathode gases pass through a space between individual slot patterns. The catalysts are located in the upper part of the shielded slot plate. Therefore, triple phase boundaries can be generated, and carbonate ions can act as the mobile charge carrier for the MCFC. Due to these properties, the shielded slot plate should have a sheared corrugated pattern. In order to form a sheared corrugated pattern, a slitting process is required during the first stage of the forming process. However, it is not possible to obtain a high aspect ratio in a sheared corrugated trapezoidal pattern due to the plastic strain concentration on the upper round region of the pattern. Therefore additional forming processes are required to form a high aspect-ratio pattern. For example, the two additional processes such as a "stretching process using a preform" and a "final forming process" can be done subsequent to the first slitting process. Before the final forming process, a stretching process, which forms an intermediate shape (perform), can make the strain distribution more uniform. Hence, various examples of performs were evaluated by using FEM simulation employing simplified boundary conditions. Finally, experiments involving microscopic and macroscopic observations using the proposed shape of a preform were conducted to characterize the formability of the sheared corrugated pattern. It was found that the numerical simulations are in good agreement with the experimental results.

  5. Processing of metal and oxygen from lunar deposits

    NASA Technical Reports Server (NTRS)

    Acton, Constance F.

    1992-01-01

    On the moon, some whole rocks may be ores for abundant elements, such as oxygen, but beneficiation will be important if metallic elements are sought from raw lunar dirt. In the extraction process, a beneficiated metallic ore, such as an oxide, sulfide, carbonate, or silicate mineral, is converted to reduced metal. A variety of plausible processing technologies, which includes recovery of meteoritic iron, and processing of lunar ilmenite, are described in this report.

  6. Process to restore obliterated serial numbers on metal surfaces

    NASA Technical Reports Server (NTRS)

    Young, S. G.; Parker, B.; Chisum, W. J.

    1974-01-01

    Metal smeared into grooves of serial numbers by grinding or filing can be cleaned out by process called cavitation. Ultrasonic vibrator generates very high frequency vibrations in water which create millions of microscopic bubbles. Cavitation bubbles impact metal surface at thousands of pounds per square inch pressure. Metal particles filling grooves are broken away.

  7. Process for the production of metal nitride sintered bodies and resultant silicon nitride and aluminum nitride sintered bodies

    NASA Technical Reports Server (NTRS)

    Yajima, S.; Omori, M.; Hayashi, J.; Kayano, H.; Hamano, M.

    1983-01-01

    A process for the manufacture of metal nitride sintered bodies, in particular, a process in which a mixture of metal nitrite powders is shaped and heated together with a binding agent is described. Of the metal nitrides Si3N4 and AIN were used especially frequently because of their excellent properties at high temperatures. The goal is to produce a process for metal nitride sintered bodies with high strength, high corrosion resistance, thermal shock resistance, thermal shock resistance, and avoidance of previously known faults.

  8. Process for the disposal of alkali metals

    DOEpatents

    Lewis, Leroy C.

    1977-01-01

    Large quantities of alkali metals may be safely reacted for ultimate disposal by contact with a hot concentrated caustic solution. The alkali metals react with water in the caustic solution in a controlled reaction while steam dilutes the hydrogen formed by the reaction to a safe level.

  9. A Thrombus Generation Model Applied to Aneurysms Treated with Shape Memory Polymer Foam and Metal Coils

    NASA Astrophysics Data System (ADS)

    Horn, John; Ortega, Jason; Hartman, Jonathan; Maitland, Duncan

    2015-11-01

    To prevent their rupture, intracranial aneurysms are often treated with endovascular metal coils which fill the aneurysm sac and isolate it from the arterial flow. Despite its widespread use, this method can result in suboptimal outcomes leading to aneurysm recurrence. Recently, shape memory polymer foam has been proposed as an alternative aneurysm filler. In this work, a computational model has been developed to predict thrombus formation in blood in response to such cardiovascular implantable devices. The model couples biofluid and biochemical phenomena present as the blood interacts with a device and stimulates thrombus formation. This model is applied to simulations of both metal coil and shape memory polymer foam treatments within an idealized 2D aneurysm geometry. Using the predicted thrombus responses, the performance of these treatments is evaluated and compared. The results suggest that foam-treated aneurysms may fill more quickly and more completely with thrombus than coil-filled aneurysms, potentially leading to improved long-term aneurysm healing. This work was performed in part under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  10. Metal Matrix Composite LOX Turbopump Housing Via Novel Tool-Less Net-Shape Pressure Infiltration Casting Technology

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Lee, Jonathan; Bhat, Biliyar; Wells, Doug; Gregg, Wayne; Marsh, Matthew; Genge, Gary; Forbes, John; Salvi, Alex; Cornie, James A.; Sung, Michael; Zhang, Shi-Yu; Gentz, Steven (Technical Monitor)

    2001-01-01

    Metal matrix composites (MMC) offer relatively higher specific strength, specific stiffness, lower coefficient of thermal expansion (CTE) and lower density as compared with conventional alloys. These unique properties make them very attractive for aerospace turbomachinery applications where there is ever increasing emphasis to reduce weight and cost, and to increase engine performance. Through a joint effort between NASA and Metal Matrix Cast Composites, Inc., a complex liquid oxygen (LOX) compatible turbopump housing is being redesigned and manufactured from hybrid (particulate and fibers) Aluminum MMC. To this end, a revolutionary tool-less pressure infiltration casting technology is being perfected. Ceramic preforms for the composite are 3-dimensionally printed using a stereolithography file, acquired from a CAD model. The preforms are then invested into a refractory material and pressure infiltrated with liquid metal. After casting, the refractory material is washed away leaving behind a near net-shape composite part. Benefits of this process include increased composite uniformity, no mold machining, short time from design to part, properties matching traditional methods, ability to make previously impossible to manufacture parts and no size limitations with a newly developed joining technology. The results of materials, manufacturing and design optimizations, preform joining, and sub-element tests will be presented.

  11. Metal Matrix Composite LOX Turbopump Housing Via Novel Tool-less Net-Shape Pressure Infiltration Casting Technology

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Lee, Jonathan; Bhat, Biliyar; Wells, Doug; Gregg, Wayne; Marsh, Matthew; Genge, Gary; Forbes, John; Salvi, Alex; Cornie, James A.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    Metal matrix composites (MMC) offer relatively higher specific strength, specific stiffness, lower coefficient of thermal expansion (CTE) and lower density as compared with conventional alloys. These unique properties make them very attractive for aerospace turbomachinery applications where there is ever increasing emphasis to reduce weight and cost, and to increase engine performance. Through a joint effort between NASA and Metal Matrix Cast Composites, Inc., a complex liquid oxygen (LOX) compatible turbopump housing is being redesigned and manufactured from hybrid (particulate and fibers) Aluminum MMC. To this end, a revolutionary toolless pressure infiltration casting technology is being perfected. Ceramic preforms for the composite are 3-dimensionally printed using a stereolithography file, acquired from a CAD model. The preforms are then invested into a refractory material and pressure infiltrated with liquid metal. After casting, the refractory material is washed away leaving behind a near net-shape composite part. Benefits of this process include increased composite uniformity, no mold machining, short time from design to part, properties matching traditional methods, ability to make previously impossible to manufacture parts and no size limitations with a newly developed joining technology. The results of materials, manufacturing and design optimizations, preform joining, and sub-element tests will be presented.

  12. Metal Matrix Composite LOX Turbopump Housing Via Novel Tool-Less Net-Shape Pressure Infiltration Casting Technology

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Lee, Jonathan; Bhat, Biliyar; Wells, Doug; Gregg, Wayne; Marsh, Matthew; Genge, Gary; Forbes, John; Salvi, Alex; Cornie, James A.; Gentz, Steven (Technical Monitor)

    2001-01-01

    Metal matrix composites (MMC) offer relatively higher specific strength, specific stiffness, lower coefficient of thermal expansion (CTE) and lower density as compared with conventional alloys. These unique properties make them very attractive for aerospace turbomachinery applications where there is ever increasing emphasis to reduce weight and cost, and to increase engine performance. Through a joint effort between NASA and Metal Matrix Cast Composites, Inc., a complex liquid oxygen (LOX) compatible turbopump housing is being redesigned and manufactured from hybrid (particulate and Fibers) Aluminum MMC. To this end, a revolutionary tool-less pressure infiltration casting technology is being perfected. Ceramic preforms for the composite are 3-dimensionally printed using a stereolithography file, acquired from a CAD model. The preforms are then invested into a refractory material and pressure infiltrated with liquid metal. After casting, the refractory material is washed away leaving behind a near net-shape composite part. Benefits of this process include increased composite uniformity, no mold machining, short time from design to part properties matching traditional methods, ability to make previously impossible to manufacture parts and no size limitations with a newly developed joining technology. The results of materials, manufacturing and design optimizations, preform joining, and sub element tests will be presented.

  13. Near net shape processing of continuous lengths of superconducting wire

    DOEpatents

    Danyluk, Steven; McNallan, Michael; Troendly, Robert; Poeppel, Roger; Goretta, Kenneth; Lanagan, Michael

    1997-01-01

    A system and method for mechanically forming a ceramic superconductor product. A system for making the ceramic superconductor includes a metallic channel portion having a cross section for receiving a ceramic superconductor powder, a roll to mechanically reduce the channel cross section and included superconductor powder and a cap portion welded to the channel portion using a localized high energy source. The assembled bar is then mechanically reduced to form a tape or wire end product.

  14. Near net shape processing of continuous lengths of superconducting wire

    DOEpatents

    Danyluk, S.; McNallan, M.; Troendly, R.; Poeppel, R.; Goretta, K.; Lanagan, M.

    1997-08-26

    A system and method for mechanically forming a ceramic superconductor product are disclosed. A system for making the ceramic superconductor includes a metallic channel portion having a cross section for receiving a ceramic superconductor powder, a roll to mechanically reduce the channel cross section and included superconductor powder and a cap portion welded to the channel portion using a localized high energy source. The assembled bar is then mechanically reduced to form a tape or wire end product. 9 figs.

  15. Shape and surface chemistry effects on the cytotoxicity and cellular uptake of metallic nanorods and nanospheres.

    PubMed

    Favi, Pelagie Marlene; Valencia, Mariana Morales; Elliott, Paul Robert; Restrepo, Alejandro; Gao, Ming; Huang, Hanchen; Pavon, Juan Jose; Webster, Thomas Jay

    2015-12-01

    Metallic nanoparticles (such as gold and silver) have been intensely studied for wound healing applications due to their ability to be easily functionalized, possess antibacterial properties, and their strong potential for targeted drug release. In this study, rod-shaped silver nanorods (AgNRs) and gold nanorods (AuNRs) were fabricated by electron beam physical vapor deposition (EBPVD), and their cytotoxicity toward human skin fibroblasts were assessed and compared to sphere-shaped silver nanospheres (AgNSs) and gold nanospheres (AuNSs). Results showed that the 39.94 nm AgNSs showed the greatest toxicity with fibroblast cells followed by the 61.06 nm AuNSs, ∼556 nm × 47 nm (11.8:1 aspect ratio) AgNRs, and the ∼534 nm × 65 nm (8.2:1 aspect ratio) AuNRs demonstrated the least amount of toxicity. The calculated IC50 (50% inhibitory concentration) value for the AgNRs exposed to fibroblasts was greater after 4 days of exposure (387.3 μg mL(-1)) compared to the AgNSs and AuNSs (4.3 and 23.4 μg mL(-1), respectively), indicating that these spherical metallic nanoparticles displayed a greater toxicity to fibroblast cells. The IC50 value could not be measured for the AuNRs due to an incomplete dose response curve. The reduced cell toxicity with the presently developed rod-shaped nanoparticles suggests that they may be promising materials for use in numerous biomedical applications.

  16. Shape and surface chemistry effects on the cytotoxicity and cellular uptake of metallic nanorods and nanospheres.

    PubMed

    Favi, Pelagie Marlene; Valencia, Mariana Morales; Elliott, Paul Robert; Restrepo, Alejandro; Gao, Ming; Huang, Hanchen; Pavon, Juan Jose; Webster, Thomas Jay

    2015-12-01

    Metallic nanoparticles (such as gold and silver) have been intensely studied for wound healing applications due to their ability to be easily functionalized, possess antibacterial properties, and their strong potential for targeted drug release. In this study, rod-shaped silver nanorods (AgNRs) and gold nanorods (AuNRs) were fabricated by electron beam physical vapor deposition (EBPVD), and their cytotoxicity toward human skin fibroblasts were assessed and compared to sphere-shaped silver nanospheres (AgNSs) and gold nanospheres (AuNSs). Results showed that the 39.94 nm AgNSs showed the greatest toxicity with fibroblast cells followed by the 61.06 nm AuNSs, ∼556 nm × 47 nm (11.8:1 aspect ratio) AgNRs, and the ∼534 nm × 65 nm (8.2:1 aspect ratio) AuNRs demonstrated the least amount of toxicity. The calculated IC50 (50% inhibitory concentration) value for the AgNRs exposed to fibroblasts was greater after 4 days of exposure (387.3 μg mL(-1)) compared to the AgNSs and AuNSs (4.3 and 23.4 μg mL(-1), respectively), indicating that these spherical metallic nanoparticles displayed a greater toxicity to fibroblast cells. The IC50 value could not be measured for the AuNRs due to an incomplete dose response curve. The reduced cell toxicity with the presently developed rod-shaped nanoparticles suggests that they may be promising materials for use in numerous biomedical applications. PMID:26053238

  17. Circularly polarized triple band glass shaped monopole patch antenna with metallic reflector for bluetooth & wireless applications

    NASA Astrophysics Data System (ADS)

    Jangid, K. G.; Choudhary, N.; Jain, P.; Sharma, B. R.; Saini, J. S.; Kulhar, V. S.; Bhatnagar, D.

    2016-03-01

    This paper presents the design and performance of strip line fed glass shaped monopole patch antenna having with overall size 30mm × 30 mm × 1.59 mm. In the patch; an eight shaped slot and in the ground plane an eight shaped ring are introduced. A metallic ground plane is also introduced at appropriate location beneath the ground plane. The proposed antenna is simulated by applying CST Microwave Studio simulator. Antenna provides circularly polarized radiations, triple broad impedance bandwidth of 203MHz (2.306GHz to 2.510GHz), 42MHz (2.685GHz to 2.757GHz) & GHz (3.63 GHz to 6.05 GHz), high flat gain (close to 5dBi) and good radiation properties in the desired frequency range. This antenna may be a very useful tool for 2.45GHz Bluetooth communication band as well as for 2.4GHz/5.2 GHz /5.8 GHz WLAN bands & 3.7GHz/5.5 GHz Wi-Max bands.

  18. Development of a process for producing ribbon shaped boron filaments

    NASA Technical Reports Server (NTRS)

    Basche, M.; Jacob, B.

    1973-01-01

    A ribbon-shaped boron filament with a tensile strength of 138 KN/sq cm (200 ksi) was investigated. The investigation was carried out using both carbon and tungsten as substrate materials. No satisfactory results were obtained utilizing uncoated, copper-plated or silicon carbide coated tungsten ribbon substrates. Carbon ribbon substrates were prepared by pyrolysis of stretched polyimide tape. A severe deposition gradient occurred in all dc reactor experiments due to convective cooling at the edge of the substrate that resulted in a weak, nonuniform filament. RF heating, however, completely eliminated this gradient problem and a 90 cm (35.5 in.) long boron ribbon was produced at .85 cm/sec (100 ft/hr) using a frequency of 40.68 megahertz. This boron ribbon, however, exhibited a light-bulb effect during deposition to 59 KN/sq cm (85.7 ksi) were obtained from this ribbon. Several silicon carbide ribbon shaped filaments were also produced during this investigation by decomposition of CH3SiHCl2 onto carbon substrates. Contrary to the boron work, silicon carbide ribbon was readily prepared in dc static reactors. A very uniform and smooth deposition was obtained with strengths up to 71.1 KN/sq cm (103.5 ksi).

  19. Fabrication and Characterization of a Micromachined Swirl-Shaped Ionic Polymer Metal Composite Actuator with Electrodes Exhibiting Asymmetric Resistance

    PubMed Central

    Feng, Guo-Hua; Liu, Kim-Min

    2014-01-01

    This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation. PMID:24824370

  20. Process for preparing liquid metal electrical contact device

    NASA Technical Reports Server (NTRS)

    Lovell, R. R.; Berkopec, F. D.; Culp, D. H. (Inventor)

    1977-01-01

    The parts of an electrical contact device are treated by sputter etching to remove the parent metal oxide. Prior to exposure of the electrodes to any oxygen, a sacrificial metal is sputter deposited on the parts. Preferably this sacrificial metal is one that oxidizes slowly and is readily dissolved by the liquid metal. The sacrificial metal may then be removed from unwanted areas. The remainder of the ring and the probe to be wet by the liquid metal are submerged in the liquid metal or the liquid metal is flushed over these areas, preferably while they are being slightly abraded, unitl all the sacrificial material on these portions is wet by the liquid metal. In doing so the liquid metal dissolves the sacrificial metal and permanently wets the parent metal. Preferred materials used in the process and for the electrodes of electrical contact devices are high purity (99.0%) nickel or AISI type 304 stainless steel for the electrical contact devices, gallium as the liquid metal, and gold as the sacrificial material.

  1. Effect of Individual Layer Shape on the Mechanical Properties of Dissimilar Al Alloys Laminated Metal Composite Sheets

    NASA Astrophysics Data System (ADS)

    Chen, Zejun; Wu, Xia; Hu, Hongbo; Chen, Quanzhong; Liu, Qing

    2014-03-01

    For the dissimilar laminated metal composite sheets (LMCS) fabricated by roll bonding technology, the great differences of mechanical properties between the constituent metals lead to the non-uniform deformation and individual layer necking. The individual layer shape affects the mechanical properties and microstructure of dissimilar LMCS. The Al/Al alloy (1100/7075) LMCS with the same thickness and ratio of dissimilar metals, but different individual layer shapes, have been successfully fabricated by hot accumulative roll bonding in conjunction with cold rolling technology. Some effective methods (such as sheet crown, warp degree, and slant angle) were presented to quantitatively evaluate the individual layer shape and necking of constituent metals. The microstructure and mechanical properties of 1100/7075 LMCS with different individual layer shapes were investigated. The effects of bonding interface on the mechanical properties were obtained based on the assessment of individual layer shapes and necking. The strength and elongation of LMCS decrease with the increase of variation of individual layer shapes and necking when the number of layers keeps constant. The research results offer some theoretical guides and references for adjusting the control measures of compatibility deformation, optimizing the hot roll bonding technologies, and designing the novel high-performance dissimilar LMCS.

  2. CONTINUOUS DISSOLVER EXTRACTOR FOR PROCESSING METAL

    DOEpatents

    Lemon, R.B.; Buckham, J.A.

    1959-02-01

    An apparatus is presented for the continuous dissolution of metal slugs in an aqueous acid and sequential continuous extraction of selected metal values from the acid solution by counter-current contact with an organic solvent. The apparatus comprises a cylindrical tank divided into upper and lower sections. Dissolution of the metal slug takes place in the lower section and the solution so produced is continuously fed to the topmost plate of the upper extraction section. An immiscible organic extractant is continuously passed by a pulsing pump into the lowermost unit of the extraction section. Suitable piping and valving permits of removing the aqueous raffinate solution from the lowermost portion of the extraction section, and simultaneous removal of organic solvent extractant containing the desired product from the uppermost portion of the extraction section.

  3. Alkali metal recovery from carbonaceous material conversion process

    DOEpatents

    Sharp, David W.; Clavenna, LeRoy R.; Gorbaty, Martin L.; Tsou, Joe M.

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced in the gasifier or similar reaction zone, alkali metal constitutents are recovered from the particles by withdrawing and passing the particles from the reaction zone to an alkali metal recovery zone in the substantial absence of molecular oxygen and treating the particles in the recovery zone with water or an aqueous solution in the substantial absence of molecular oxygen. The solution formed by treating the particles in the recovery zone will contain water-soluble alkali metal constituents and is recycled to the conversion process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. Preventing contact of the particles with oxygen as they are withdrawn from the reaction zone and during treatment in the recovery zone avoids the formation of undesirable alkali metal constituents in the aqueous solution produced in the recovery zone and insures maximum recovery of water-soluble alkali metal constituents from the alkali metal residues.

  4. Understanding metallic bonding: Structure, process and interaction by Rasch analysis

    NASA Astrophysics Data System (ADS)

    Cheng, Maurice M. W.; Oon, Pey-Tee

    2016-08-01

    This paper reports the results of a survey of 3006 Year 10-12 students on their understandings of metallic bonding. The instrument was developed based on Chi's ontological categories of scientific concepts and students' understanding of metallic bonding as reported in the literature. The instrument has two parts. Part one probed into students' understanding of metallic bonding as (a) a submicro structure of metals, (b) a process in which individual metal atoms lose their outermost shell electrons to form a 'sea of electrons' and octet metal cations or (c) an all-directional electrostatic force between delocalized electrons and metal cations, that is, an interaction. Part two assessed students' explanation of malleability of metals, for example (a) as a submicro structural rearrangement of metal atoms/cations or (b) based on all-directional electrostatic force. The instrument was validated by the Rasch Model. Psychometric assessment showed that the instrument possessed reasonably good properties of measurement. Results revealed that it was reliable and valid for measuring students' understanding of metallic bonding. Analysis revealed that the structure, process and interaction understandings were unidimensional and in an increasing order of difficulty. Implications for the teaching of metallic bonding, particular through the use of diagrams, critiques and model-based learning, are discussed.

  5. Automation of Axisymmetric Drop Shape Analysis Using Digital Image Processing

    NASA Astrophysics Data System (ADS)

    Cheng, Philip Wing Ping

    The Axisymmetric Drop Shape Analysis - Profile (ADSA-P) technique, as initiated by Rotenberg, is a user -oriented scheme to determine liquid-fluid interfacial tensions and contact angles from the shape of axisymmetric menisci, i.e., from sessile as well as pendant drops. The ADSA -P program requires as input several coordinate points along the drop profile, the value of the density difference between the bulk phases, and gravity. The solution yields interfacial tension and contact angle. Although the ADSA-P technique was in principle complete, it was found that it was of very limited practical use. The major difficulty with the method is the need for very precise coordinate points along the drop profile, which, up to now, could not be obtained readily. In the past, the coordinate points along the drop profile were obtained by manual digitization of photographs or negatives. From manual digitization data, the surface tension values obtained had an average error of +/-5% when compared with literature values. Another problem with the ADSA-P technique was that the computer program failed to converge for the case of very elongated pendant drops. To acquire the drop profile coordinates automatically, a technique which utilizes recent developments in digital image acquisition and analysis was developed. In order to determine the drop profile coordinates as precisely as possible, the errors due to optical distortions were eliminated. In addition, determination of drop profile coordinates to pixel and sub-pixel resolution was developed. It was found that high precision could be obtained through the use of sub-pixel resolution and a spline fitting method. The results obtained using the automatic digitization technique in conjunction with ADSA-P not only compared well with the conventional methods, but also outstripped the precision of conventional methods considerably. To solve the convergence problem of very elongated pendant drops, it was found that the reason for the

  6. Net Shaped Component Fabrication of Refractory Metal Alloys using Vacuum Plasma Spraying

    NASA Technical Reports Server (NTRS)

    Sen, S.; ODell, S.; Gorti, S.; Litchford, R.

    2006-01-01

    The vacuum plasma spraying (VPS) technique was employed to produce dense and net shaped components of a new tungsten-rhenium (W-Re) refractory metal alloy. The fine grain size obtained using this technique enhanced the mechanical properties of the alloy at elevated temperatures. The alloy development also included incorporation of thermodynamically stable dispersion phases to pin down grain boundaries at elevated temperatures and thereby circumventing the inherent problem of recrystallization of refractory alloys at elevated temperatures. Requirements for such alloys as related to high temperature space propulsion components will be discussed. Grain size distribution as a function of cooling rate and dispersion phase loading will be presented. Mechanical testing and grain growth results as a function of temperature will also be discussed.

  7. Resonant transmission and mode modulation of acoustic waves in H-shaped metallic gratings

    SciTech Connect

    Deng, Yu-Qiang; Fan, Ren-Hao; Zhang, Kun; Peng, Ru-Wen E-mail: dongxiang87@gmail.com; Qi, Dong-Xiang E-mail: dongxiang87@gmail.com

    2015-04-15

    In this work, we demonstrate that resonant full transmission of acoustic waves exists in subwavelength H-shaped metallic gratings, and transmission peaks can be efficiently tuned by adjusting the grating geometry. We investigate this phenomenon through both numerical simulations and theoretical calculations based on rigorous-coupled wave analysis. The transmission peaks are originated from Fabry-Perot resonances together with the couplings between the diffractive wave on the surface and the multiple guided modes in the slits. Moreover, the transmission modes can be efficiently tuned by adjusting the cavity geometry, without changing the grating thickness. The mechanism is analyzed based on an equivalent circuit model and verified by both the theoretical calculations and the numerical simulations. This research has potential application in acoustic-device miniaturization over a wide range of wavelengths.

  8. Tuning the vibration of a rotor with shape memory alloy metal rubber supports

    NASA Astrophysics Data System (ADS)

    Ma, Yanhong; Zhang, Qicheng; Zhang, Dayi; Scarpa, Fabrizio; Liu, Baolong; Hong, Jie

    2015-09-01

    The paper describes a novel smart rotor support damper with variable stiffness made with a new multifunctional material - the shape memory alloy metal rubber (SMA-MR). SMA-MR gives high load bearing capability (yield limit up to 100 MPa and stiffness exceeding 1e8 N/m), high damping (loss factor between 0.15 and 0.3) and variable stiffness (variation of 2.6 times between martensite and austenite phases). The SMA-MR has been used to replace a squeeze film damper and combined with an elastic support. The mechanical performance of the smart support damper has been investigated at room and high temperatures on a rotor test rig. The vibration tuning capabilities of the SMA-MR damper have been evaluated through FEM simulations and experimental tests. The study shows the feasibility of using the SMA-MR material for potential applications of active vibration control at different temperatures in rotordynamics systems.

  9. Gastrotracheal fistula: Treatment with a covered elf-expanding Y-shaped metallic stent

    PubMed Central

    Wang, Fei; Yu, Hong; Zhu, Ming-Hui; Li, Quan-Peng; Ge, Xian-Xiu; Nie, Jun-Jie; Miao, Lin

    2015-01-01

    A 67-year-old man had a sev-ere cough and pulmonary infection for 1 wk before seeking evaluation at our hospital. He had undergone esophagectomy with gastric pull-up and radiotherapy for esophageal cancer 3 years previously. After admission to our hospital, gastroscopy and bronchoscopy revealed a fistulous communication between the posterior tracheal wall near the carina and the upper residual stomach. We measured the diameter of the trachea and bronchus and determined the site and size of the fistula using multislice computed tomography and gastroscopy. A covered self-expanding Y-shaped metallic stent was implanted into the trachea and bronchus. Subsequently, the fistula was closed completely. The patient tolerated the stent well and had good palliation of his symptoms. PMID:25624743

  10. Conical shaped charge pressed powder, metal liner jet characterization and penetration in aluminum

    SciTech Connect

    Vigil, M.G.

    1997-05-01

    This work was conducted as part of a Near-wellbore Mechanics program at Sandia National Laboratories. An understanding of the interaction of the perforator jet from an explosive shaped charge with the fluid filled porous sandstone media is of basic importance to the completion of oil wells. Tests were conducted using the five-head Flash X-ray Test Site to measure the jet tip velocities and jet geometry for the OMNI and CAPSULE Conical Shaped Charge (CSC) oil well perforator jets fired into air. These tests were conducted to generate jet velocity and geometry information to be used in validating the CTH hydrocode modeling/simulation development of pressed powder, metal liner jets in air. Ten tests were conducted to determine the CSC jet penetration into 6061-T6 aluminum targets. Five tests were conducted with the OMNI CSC at 0.25, 6.0, and 19 inch standoffs from the target. Five tests were conducted with the CAPSULE CSC at 0.60, 5.0, 10.0, and 19 inch standoffs from the target. These tests were conducted to generate jet penetration into homogeneous target information for use in validating the CTH code modeling/simulation of pressed powder, metal liner jets penetrating aluminum targets. The Flash X-ray radiographs, jet velocities, jet diameters, and jet lengths data for jets fired into air are presented in this report. The jet penetration into aluminum and penetration hole profile data are also presented for the OMNI and CAPSULE perforators. Least Squares fits are presented for the measured jet velocity and jet penetration data.

  11. The shape of mammalian phylogeny: patterns, processes and scales

    PubMed Central

    Purvis, Andy; Fritz, Susanne A.; Rodríguez, Jesús; Harvey, Paul H.; Grenyer, Richard

    2011-01-01

    Mammalian phylogeny is far too asymmetric for all contemporaneous lineages to have had equal chances of diversifying. We consider this asymmetry or imbalance from four perspectives. First, we infer a minimal set of ‘regime changes’—points at which net diversification rate has changed—identifying 15 significant radiations and 12 clades that may be ‘downshifts’. We next show that mammalian phylogeny is similar in shape to a large set of published phylogenies of other vertebrate, arthropod and plant groups, suggesting that many clades may diversify under a largely shared set of ‘rules’. Third, we simulate six simple macroevolutionary models, showing that those where speciation slows down as geographical or niche space is filled, produce more realistic phylogenies than do models involving key innovations. Lastly, an analysis of the spatial scaling of imbalance shows that the phylogeny of species within an assemblage, ecoregion or larger area always tends to be more unbalanced than expected from the phylogeny of species at the next more inclusive spatial scale. We conclude with a verbal model of mammalian macroevolution, which emphasizes the importance to diversification of accessing new regions of geographical or niche space. PMID:21807729

  12. Processing of X-ray Microcalorimeter Data with Pulse Shape Variation using Principal Component Analysis

    NASA Astrophysics Data System (ADS)

    Yan, D.; Cecil, T.; Gades, L.; Jacobsen, C.; Madden, T.; Miceli, A.

    2016-07-01

    We present a method using principal component analysis (PCA) to process x-ray pulses with severe shape variation where traditional optimal filter methods fail. We demonstrate that PCA is able to noise-filter and extract energy information from x-ray pulses despite their different shapes. We apply this method to a dataset from an x-ray thermal kinetic inductance detector which has severe pulse shape variation arising from position-dependent absorption.

  13. X-ray line shapes of metals: Exact solutions of a final-state interaction model

    NASA Astrophysics Data System (ADS)

    Swarts, Coenraad A.; Dow, John D.

    2005-10-01

    By means of model calculations for an independent-electron metal, we obtain exact line shapes for the photon absorption, emission, and photoemission spectra of core states, including electronic relaxation. In all cases we find an x-ray edge anomaly. For the absorption and emission spectra this anomaly is superposed on a continuum resembling Elliott exciton theory. We display how the spectra evolve from the exciton limit to the free-electron limit as the final-state interaction strength is decreased or the Fermi energy increased. We compare the spectra obtained for different final-state interactions and find that different types of interactions produce different spectral shapes. Away from threshold the absorption and emission profiles show an enhancement of the free-electron result, as predicted by the screened-exciton theory. Our results offer potential explanations for (i) incompatibilities between threshold exponents and exponents extracted from other data, (ii) the occurrence of nearly symmetric x-ray photoemission lines, and (iii) the lack of mirror symmetry of absorption and emission edges.

  14. Texture and Crystal Orientation in Ti-6Al-4V Builds Fabricated by Shaped Metal Deposition

    NASA Astrophysics Data System (ADS)

    Baufeld, Bernd; van der Biest, Omer; Dillien, Steven

    2010-08-01

    The texture and crystal orientation of Ti-6Al-4V components, manufactured by shaped metal deposition (SMD), is investigated. SMD is a novel rapid prototyping tungsten inert gas (TIG) welding technique leading to near-net-shape components. This involves sequential layer by layer deposition with repeated partial melting and heat treatment, which results in epitaxial growth of large elongated prior β grains. This leads to a directionally solidified texture, where the prior β grains exhibit only a small misorientation with each other. The β grains grow in left< { 100} rightrangle direction with a second left< { 100} rightrangle direction perpendicular to the wall surface. During cooling, the α phase transformation follows the Burgers orientation relationship leading to a Widmanstätten structure, with orientation relations between most of the α lamellae and also of the residual β phase. The directionally solidification and the transformation into the α phase following the Burgers relationship results in a texture, where the hcp pole figures look similar to bcc pole figures.

  15. 3D display and image processing system for metal bellows welding

    NASA Astrophysics Data System (ADS)

    Park, Min-Chul; Son, Jung-Young

    2010-04-01

    Industrial welded metal Bellows is in shape of flexible pipeline. The most common form of bellows is as pairs of washer-shaped discs of thin sheet metal stamped from strip stock. Performing arc welding operation may cause dangerous accidents and bad smells. Furthermore, in the process of welding operation, workers have to observe the object directly through microscope adjusting the vertical and horizontal positions of welding rod tip and the bellows fixed on the jig, respectively. Welding looking through microscope makes workers feel tired. To improve working environment that workers sit in an uncomfortable position and productivity we introduced 3D display and image processing. Main purpose of the system is not only to maximize the efficiency of industrial productivity with accuracy but also to keep the safety standards with the full automation of work by distant remote controlling.

  16. Elemental metals for environmental remediation: learning from cementation process.

    PubMed

    Noubactep, C

    2010-09-15

    The further development of Fe(0)-based remediation technology depends on the profound understanding of the mechanisms involved in the process of aqueous contaminant removal. The view that adsorption and co-precipitation are the fundamental contaminant removal mechanisms is currently facing a harsh scepticism. Results from electrochemical cementation are used to bring new insights in the process of contaminant removal in Fe(0)/H(2)O systems. The common feature of hydrometallurgical cementation and metal-based remediation is the heterogeneous nature of the processes which inevitably occurs in the presence of a surface scale. The major difference between both processes is that the surface of remediation metals is covered by layers of own oxide(s) while the surface of the reducing metal in covered by porous layers of the cemented metal. The porous cemented metal is necessarily electronic conductive and favours further dissolution of the reducing metal. For the remediation metal, neither a porous layer nor a conductive layer could be warrant. Therefore, the continuation of the remediation process depends on the long-term porosity of oxide scales on the metal surfaces. These considerations rationalized the superiority of Fe(0) as remediation agent compared to thermodynamically more favourable Al(0) and Zn(0). The validity of the adsorption/co-precipitation concept is corroborated.

  17. Process for removing metal contaminants from used lubricating oils

    SciTech Connect

    Johnson, C.B.

    1980-05-27

    A process is provided for removing metal contaminants from used lubricating oil. The used oil is contacted with an aqueous solution of aluminum sulphate and ammonium sulphate at elevated temperature to form compounds of the metal contaminants in an aqueous phase which is phase separable from the oil. An oil product reduced in metal contaminants is thereby produced which is suitable as a cheap fuel or lubricant.

  18. A MEMS probe card with 2D dense-arrayed 'hoe'-shaped metal tips

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Li, Xinxin; Feng, Songlin

    2008-05-01

    In this paper, we present a novel MEMS probe card with densely area-arrayed microprobes for the wafer-level test of advanced ICs. In a 4 inch silicon wafer, a total of about 110 000 probe tips can be simultaneously fabricated, with a two-dimensional tip pitch of 240 µm × 160 µm. The 'hoe-shaped' microprobe structure is composed of one or two planar arms and an up-tilted tip, both of which are high-yield fabricated with metal micromachining techniques including low-stress nickel electroplating. With micromachined cavities, the silicon wafer serves as moulds for the up-tilted metal probes. Then, the microprobes are finally flip-chip packaged to a ceramic board for further connection to automatic testing equipment (ATE). After the probe structures are formed, the silicon wafer is removed completely by using TMAH wet etching, while the probes are freed by silicon laterally etching. The measured spring constants for all the three types of probes agree well with the designed values. As both mechanical anchors and electrical interconnections, the Sn-Ag solder-bumps feature satisfactory properties. The tested contact resistance values for three different thin-film pads on dies under test are always below 0.8 Ω, while the current leakage between two adjacent probes is only about 150 pA under 3.3 V.

  19. PROCESS FOR SEPARATION OF HEAVY METALS

    DOEpatents

    Duffield, R.B.

    1958-04-29

    A method is described for separating plutonium from aqueous acidic solutions of neutron-irradiated uranium and the impurities associated therewith. The separation is effected by adding, to the solution containing hexavalent uranium and plutonium, acetate ions and the ions of an alkali metal and those of a divalent metal and thus forming a complex plutonium acetate salt which is carried by the corresponding complex of uranium, such as sodium magnesium uranyl acetate. The plutonium may be separated from the precipitated salt by taking the same back into solution, reducing the plutonium to a lower valent state on reprecipitating the sodium magnesium uranyl salt, removing the latter, and then carrying the plutonium from ihe solution by means of lanthanum fluoride.

  20. The Fingertip Effect: How Information-Processing Technology Shapes Thinking.

    ERIC Educational Resources Information Center

    Perkins, D. N.

    1985-01-01

    Typical contacts with information-processing technology (IPT) do not significantly reshape thought. Although some suggest that IPT will have a narrowing, dehumanizing influence, the diversification of ITP now underway will allow for more styles of involvement. Because of this diversification, thinking may change as it did in response to literacy…

  1. Tribological properties of silicon carbide in metal removal process

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1980-01-01

    Material properties are considered as they relate to adhesion, friction, and wear of single crystal silicon carbide in contact with metals and alloys that are likely to be involved in a metal removal process such as grinding. Metal removal from adhesion between sliding surfaces in contact and metal removal as a result of the silicon carbide sliding against a metal, indenting into it, and plowing a series of grooves or furrows are discussed. Fracture and deformation characteristics of the silicon carbide surface are also covered. The adhesion, friction, and metal transfer to silicon carbide is related to the relative chemical activity of the metals. The more active the metal, the higher the adhesion and friction, and the greater the metal transfer to silicon carbide. Atomic size and content of alloying elements play a dominant role in controlling adhesion, friction, and abrasive wear properties of alloys. The friction and abrasive wear (metal removal) decrease linearly as the shear strength of the bulk metal increases. They decrease as the solute to solvent atomic radius ratio increases or decreases linearly from unity, and with an increase of solute content. The surface fracture of silicon carbide is due to cleavages of 0001, 10(-1)0, and/or 11(-2)0 planes.

  2. HOW MANY NUCLEOSYNTHESIS PROCESSES EXIST AT LOW METALLICITY?

    SciTech Connect

    Hansen, C. J.; Montes, F.; Arcones, A. E-mail: cjhansen@dark-cosmology.dk E-mail: almudena.arcones@physik.tu-darmstadt.de

    2014-12-20

    Abundances of low-metallicity stars offer a unique opportunity to understand the contribution and conditions of the different processes that synthesize heavy elements. Many old, metal-poor stars show a robust abundance pattern for elements heavier than Ba, and a less robust pattern between Sr and Ag. Here we probe if two nucleosynthesis processes are sufficient to explain the stellar abundances at low metallicity, and we carry out a site independent approach to separate the contribution from these two processes or components to the total observationally derived abundances. Our approach provides a method to determine the contribution of each process to the production of elements such as Sr, Zr, Ba, and Eu. We explore the observed star-to-star abundance scatter as a function of metallicity that each process leads to. Moreover, we use the deduced abundance pattern of one of the nucleosynthesis components to constrain the astrophysical conditions of neutrino-driven winds from core-collapse supernovae.

  3. An Atomistic View on Fundamental Transport Processes on Metal Surfaces

    SciTech Connect

    Giesen, Margret

    2007-06-14

    In this lecture I present an introduction to the time-resolved observation of atomic transport processes on metal surfaces using scanning tunneling microscopy video sequences. The experimental data is analyzed using scaling law concepts known from statistical thermodynamics. I will present studies from metal surfaces in vacuum as well as in electrolyte.

  4. Development of metal recycling process from decommissioned nuclear power plants

    SciTech Connect

    Ishikura, T.; Abe, S.; Sakai, H.; Takahashi, J.

    1999-07-01

    Dismantling and demolition of a nuclear power plant generates a large amount of metal waste. Recycling of such waste for resource is important because of the limited capacity of the disposal site. Authors have developed metal recycling processes. It is found that pyrometallurgical separation techniques can effectively separate nickel and cobalt, which contain main contributors of radioactivity, from iron and chromium.

  5. PROCESS OF MAKING SHAPED FUEL FOR NUCLEAR REACTORS

    DOEpatents

    O'Leary, W.J.; Fisher, E.A.

    1964-02-11

    A process for making uranium dioxide fuel of great strength, density, and thermal conductivity by mixing it with 0.1 to 1% of a densifier oxide (tin, aluminum, zirconium, ferric, zinc, chromium, molybdenum, titanium, or niobium oxide) and with a plasticizer (0.5 to 3% of bentonite and 0.05 to 2% of methylcellulose, propylene glycol alginate, or ammonium alginate), compacting the mixture obtained, and sintering the bodies in an atmosphere of carbon monoxide or carbon dioxide, with or without hydrogen, or of a nitrogen-hydrogen mixture is described. (AEC)

  6. Shaping Disk Galaxy Stellar Populations via Internal and External Processes

    NASA Astrophysics Data System (ADS)

    Roškar, Rok

    2015-03-01

    In recent years, effects such as the radial migration of stars in disks have been recognized as important drivers of the properties of stellar populations. Radial migration arises due to perturbative effects of disk structures such as bars and spiral arms, and can deposit stars formed in disks to regions far from their birthplaces. Migrant stars can significantly affect the demographics of their new locales, especially in low-density regions such as in the outer disks. However, in the cosmological environment, other effects such as mergers and filamentary gas accretion also influence the disk formation process. Understanding the relative importance of these processes on the detailed evolution of stellar population signatures is crucial for reconstructing the history of the Milky Way and other nearby galaxies. In the Milky Way disk in particular, the formation of the thickened component has recently attracted much attention due to its potential to serve as a diagnostic of the galaxy's early history. Some recent work suggests, however, that the vertical structure of Milky Way stellar populations is consistent with models that build up the thickened component through migration. I discuss these developments in the context of cosmological galaxy formation.

  7. PROCESSING OF URANIUM-METAL-CONTAINING FUEL ELEMENTS

    DOEpatents

    Moore, R.H.

    1962-10-01

    A process is given for recovering uranium from neutronbombarded uranium- aluminum alloys. The alloy is dissolved in an aluminum halide--alkali metal halide mixture in which the halide is a mixture of chloride and bromide, the aluminum halide is present in about stoichiometric quantity as to uranium and fission products and the alkali metal halide in a predominant quantity; the uranium- and electropositive fission-products-containing salt phase is separated from the electronegative-containing metal phase; more aluminum halide is added to the salt phase to obtain equimolarity as to the alkali metal halide; adding an excess of aluminum metal whereby uranium metal is formed and alloyed with the excess aluminum; and separating the uranium-aluminum alloy from the fission- productscontaining salt phase. (AEC)

  8. Metal Catalyzed Fusion: Nuclear Active Environment vs. Process

    NASA Astrophysics Data System (ADS)

    Chubb, Talbot

    2009-03-01

    To achieve radiationless dd fusion and/or other LENR reactions via chemistry: some focus on environment of interior or altered near-surface volume of bulk metal; some on environment inside metal nanocrystals or on their surface; some on the interface between nanometal crystals and ionic crystals; some on a momentum shock-stimulation reaction process. Experiment says there is also a spontaneous reaction process.

  9. Fiber Metal Laminates Made by the VARTM Process

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.; Cano, Roberto J.; Hales, Stephen J.; Alexa, Joel A.; Weiser, Erik S.; Loos, Alfred; Johnson, W.S.

    2009-01-01

    Fiber metal laminates (FMLs) are multi-component materials utilizing metals, fibers and matrix resins. Tailoring their properties is readily achievable by varying one or more of these components. Established FMLs like GLARE utilize aluminum foils, glass fibers and epoxy matrices and are manufactured using an autoclave. Two new processes for manufacturing FMLs using vacuum assisted resin transfer molding (VARTM) have been developed at the NASA Langley Research Center (LaRC). A description of these processes and the resulting FMLs are presented.

  10. Effects of Processing Parameters on the Forming Quality of C-Shaped Thermosetting Composite Laminates in Hot Diaphragm Forming Process

    NASA Astrophysics Data System (ADS)

    Bian, X. X.; Gu, Y. Z.; Sun, J.; Li, M.; Liu, W. P.; Zhang, Z. G.

    2013-10-01

    In this study, the effects of processing temperature and vacuum applying rate on the forming quality of C-shaped carbon fiber reinforced epoxy resin matrix composite laminates during hot diaphragm forming process were investigated. C-shaped prepreg preforms were produced using a home-made hot diaphragm forming equipment. The thickness variations of the preforms and the manufacturing defects after diaphragm forming process, including fiber wrinkling and voids, were evaluated to understand the forming mechanism. Furthermore, both interlaminar slipping friction and compaction behavior of the prepreg stacks were experimentally analyzed for showing the importance of the processing parameters. In addition, autoclave processing was used to cure the C-shaped preforms to investigate the changes of the defects before and after cure process. The results show that the C-shaped prepreg preforms with good forming quality can be achieved through increasing processing temperature and reducing vacuum applying rate, which obviously promote prepreg interlaminar slipping process. The process temperature and forming rate in hot diaphragm forming process strongly influence prepreg interply frictional force, and the maximum interlaminar frictional force can be taken as a key parameter for processing parameter optimization. Autoclave process is effective in eliminating voids in the preforms and can alleviate fiber wrinkles to a certain extent.

  11. Sol-gel processing with inorganic metal salt precursors

    DOEpatents

    Hu, Zhong-Cheng

    2004-10-19

    Methods for sol-gel processing that generally involve mixing together an inorganic metal salt, water, and a water miscible alcohol or other organic solvent, at room temperature with a macromolecular dispersant material, such as hydroxypropyl cellulose (HPC) added. The resulting homogenous solution is incubated at a desired temperature and time to result in a desired product. The methods enable production of high quality sols and gels at lower temperatures than standard methods. The methods enable production of nanosize sols from inorganic metal salts. The methods offer sol-gel processing from inorganic metal salts.

  12. Electron Beam Freeform Fabrication: A Rapid Metal Deposition Process

    NASA Technical Reports Server (NTRS)

    Taminger, Karen M. B.; Hafley, Robert A.

    2003-01-01

    Manufacturing of structural metal parts directly from computer aided design (CAD) data has been investigated by numerous researchers over the past decade. Researchers at NASA Langley REsearch Center are developing a new solid freeform fabrication process, electron beam freeform fabrication (EBF), as a rapid metal deposition process that works efficiently with a variety of weldable alloys. The EBF process introduces metal wire feedstock into a molten pool that is created and sustained using a focused electron beam in a vacuum environment. Thus far, this technique has been demonstrated on aluminum and titanium alloys of interest for aerospace structural applications nickel and ferrous based alloys are also planned. Deposits resulting from 2219 aluminum demonstrations have exhibited a range of grain morphologies depending upon the deposition parameters. These materials ave exhibited excellent tensile properties comparable to typical handbook data for wrought plate product after post-processing heat treatments. The EBF process is capable of bulk metal deposition at deposition rated in excess of 2500 cubic centimeters per hour (150 cubic inches per our) or finer detail at lower deposition rates, depending upon the desired application. This process offers the potential for rapidly adding structural details to simpler cast or forged structures rather than the conventional approach of machining large volumes of chips to produce a monolithic metallic structure. Selective addition of metal onto simpler blanks of material can have a significant effect on lead time reduction and lower material and machining costs.

  13. Process for preparing metal-carbide-containing microspheres from metal-loaded resin beads

    DOEpatents

    Beatty, Ronald L.

    1977-01-01

    An improved process for producing porous spheroidal particles consisting of a metal carbide phase dispersed within a carbon matrix is described. According to the invention metal-loaded ion-exchange resin microspheres which have been carbonized are coated with a buffer carbon layer prior to conversion of the oxide to carbide in order to maintain porosity and avoid other adverse sintering effects.

  14. Process for the regeneration of metallic catalysts

    DOEpatents

    Katzer, James R.; Windawi, Hassan

    1981-01-01

    A method for the regeneration of metallic hydrogenation catalysts from the class consisting of Ni, Rh, Pd, Ir, Pt and Ru poisoned with sulfur, with or without accompanying carbon deposition, comprising subjecting the catalyst to exposure to oxygen gas in a concentration of about 1-10 ppm. intermixed with an inert gas of the group consisting of He, A, Xe, Kr, N.sub.2 and air substantially free of oxygen to an extent such that the total oxygen molecule throughout is in the range of about 10 to 20 times that of the hydrogen sulfide molecular exposure producing the catalyst poisoning while maintaining the temperature in the range of about 300.degree. to 500.degree. C.

  15. Removal of heavy metals by hybrid electrocoagulation and microfiltration processes.

    PubMed

    Keerthi; Vinduja, V; Balasubramanian, N

    2013-01-01

    This study is based on the investigation of the performance of electrocoagulation (EC), followed by the microfiltration process for heavy metal removal in synthetic model waste water containing Zn2+, Ni2+ and Cd2+ ions. Effects of initial concentration, current density and pH on metal removal were analysed to optimize the EC process. The optimized EC process was then integrated with dead-end microfiltration (MF) and was found that the hybrid process was capable of 99% removal of heavy metals. The cake layer formed over the membrane by the hybrid process was analysed through scanning electron microscope-energy-dispersive X-ray spectroscopy. The particle size analysis of the sludge formed during EC was done to investigate the fouling caused during the process.

  16. Metal cutting analogy for establishing Friction Stir Welding process parameters

    NASA Astrophysics Data System (ADS)

    Stafford, Sylvester Allen

    A friction stir weld (FSW) is a solid state joining operation whose processing parameters are currently determined by lengthy trial and error methods. To implement FSWing rapidly in various applications will require an approach for predicting process parameters based on the physics of the process. Based on hot working conditions for metals, a kinematic model has been proposed for calculating the shear strain and shear strain rates during the FSW process, validation of the proposed model with direct measuring is difficult however. Since the shear strain and shear strain rates predicted for the FSW process, are similar to those predicted in metal cutting, validation of the FSW algorithms with microstructural studies of metal chips may be possible leading to the ability to predict FSW processing parameters.

  17. Photon-pair source with controllable delay based on shaped inhomogeneous broadening of rare-earth-metal-doped solids

    SciTech Connect

    Sekatski, Pavel; Sangouard, Nicolas; Gisin, Nicolas; Afzelius, Mikael; Riedmatten, Hugues de

    2011-05-15

    Spontaneous Raman emission in atomic gases provides an attractive source of photon pairs with a controllable delay. We show how this technique can be implemented in solid state systems by appropriately shaping the inhomogeneous broadening. Our proposal is eminently feasible with current technology and provides a realistic solution to entangle remote rare-earth-metal-doped solids in a heralded way.

  18. Processing of CuAlMn Shape Memory Foams with Open Spherical Pores by Silica-Gel Beads Infiltration Method

    NASA Astrophysics Data System (ADS)

    Li, Hua; Yuan, Bin; Gao, Yan

    2016-10-01

    A molten metal infiltration process with amorphous SiO2 (silica-gel) beads as space holders was used to prepare Cu-based shape memory foams in this article. We found that the silica-gel beads with micropores inside expanded when being heated to elevated temperatures and that proper control of the expansion of silica-gel beads helped form necks between the beads with different bonding extent, which had been taken advantage of to have a good control of the foam morphology and porosity, by carefully designing suitable procedures and choosing proper parameters for the process. In addition, we studied in detail the effect of heating temperature, silica-gel bead density, and infiltration pressure of the present process on the morphology and porosity of CuAlMn shape memory foams. By coordinating these three key parameters, CuAlMn shape memory foams with open spherical pores and adjustable porosity from 66 to 85 pct were reliably produced.

  19. Processing of CuAlMn Shape Memory Foams with Open Spherical Pores by Silica-Gel Beads Infiltration Method

    NASA Astrophysics Data System (ADS)

    Li, Hua; Yuan, Bin; Gao, Yan

    2016-08-01

    A molten metal infiltration process with amorphous SiO2 (silica-gel) beads as space holders was used to prepare Cu-based shape memory foams in this article. We found that the silica-gel beads with micropores inside expanded when being heated to elevated temperatures and that proper control of the expansion of silica-gel beads helped form necks between the beads with different bonding extent, which had been taken advantage of to have a good control of the foam morphology and porosity, by carefully designing suitable procedures and choosing proper parameters for the process. In addition, we studied in detail the effect of heating temperature, silica-gel bead density, and infiltration pressure of the present process on the morphology and porosity of CuAlMn shape memory foams. By coordinating these three key parameters, CuAlMn shape memory foams with open spherical pores and adjustable porosity from 66 to 85 pct were reliably produced.

  20. Ceramic/metal nanocomposites by lyophilization: Processing and HRTEM study

    SciTech Connect

    Gutierrez-Gonzalez, C.F.; Agouram, S.; Torrecillas, R.; Moya, J.S.; Lopez-Esteban, S.

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer A cryogenic route has been used to obtain ceramic/metal nanostructured powders. Black-Right-Pointing-Pointer The powders present good homogeneity and dispersion of metal. Black-Right-Pointing-Pointer The metal nanoparticle size distributions are centred in 17-35 nm. Black-Right-Pointing-Pointer Both phases, ceramic and metal, present a high degree of crystallinity. Black-Right-Pointing-Pointer Good metal/ceramic interfaces due to epitaxial growth, studied by HRTEM. -- Abstract: This work describes a wet-processing route based on spray-freezing and subsequent lyophilization designed to obtain nanostructured ceramic/metal powders. Starting from the ceramic powder and the corresponding metal salt, a water-based suspension is sprayed on liquid nitrogen. The frozen powders are subsequently freeze-dried, calcined and reduced. The material was analyzed using X-ray diffraction analysis at all stages. High resolution transmission electron microscopy studies showed a uniform distribution of metal nanoparticles on the ceramic grain surfaces, good interfaces and high crystallinity, with an average metal particle size in the nanometric range.

  1. Diagnostics of metal inert gas and metal active gas welding processes

    NASA Astrophysics Data System (ADS)

    Uhrlandt, D.

    2016-08-01

    The paper gives a review on studies on metal inert gas (MIG) and metal active gas (MAG) welding processes with the focus on diagnostics of the arc, the material transfer, and the temporal process behaviour in welding experiments. Recent findings with respect to an improved understanding of the main mechanisms in the welding arc and the welding process are summarized. This is linked to actual developments in welding arc and welding process modelling where measurements are indispensable for validation. Challenges of forthcoming studies are illustrated by means of methods under development for welding process control as well as remaining open questions with respect to arc-surface interaction and arc power balance.

  2. Studies on the optimization of deformation processed metal metal matrix composites

    SciTech Connect

    Ellis, T.W.

    1994-01-04

    A methodology for the production of deformation processed metal metal matrix composites from hyper-eutectic copper-chromium alloys was developed. This methodology was derived from a basic study of the precipitation phenomena in these alloys encompassing evaluation of microstructural, electrical, and mechanical properties. The methodology developed produces material with a superior combination of electrical and mechanical properties compared to those presently available in commercial alloys. New and novel alloying procedures were investigated to extend the range of production methods available for these material. These studies focused on the use of High Pressure Gas Atomization and the development of new containment technologies for the liquid alloy. This allowed the production of alloys with a much more refined starting microstructure and lower contamination than available by other methods. The knowledge gained in the previous studies was used to develop two completely new families of deformation processed metal metal matrix composites. These composites are based on immissible alloys with yttrium and magnesium matrices and refractory metal reinforcement. This work extends the physical property range available in deformation processed metal metal matrix composites. Additionally, it also represents new ways to apply these metals in engineering applications.

  3. Fast electronic relaxation in metal nanoclusters via excitation of coherent shape deformations

    NASA Astrophysics Data System (ADS)

    Kresin, Vitaly V.; Ovchinnikov, Yu. N.

    2006-03-01

    Electron-phonon relaxation in size-quantized systems may become inhibited when the spacing of discrete electron energy levels exceeds the magnitude of the phonon frequency. We show, however, that nanoclusters can support a fast nonradiative relaxation channel which derives from their distinctive ability to undergo Jahn-Teller shape deformations. Such a deformation represents a collective and coherent vibrational excitation and enables electronic transitions to occur without a multiphonon bottleneck. We analyze this mechanism for a metal cluster within the analytical framework of a three-dimensional potential well undergoing a spheroidal distortion. An expression for the time evolution of the distortion parameter is derived, the electronic level crossing condition formulated, and the probability of electronic transition at a level crossing is evaluated. An application to electron-hole recombination in a closed-shell aluminum cluster with 40 electrons shows that the short (˜250fs) excitation lifetime observed in recent pump-probe experiments can be explained by the proposed mechanism.

  4. Robust Design of Sheet Metal Forming Process Based on Kriging Metamodel

    NASA Astrophysics Data System (ADS)

    Xie, Yanmin

    2011-08-01

    Nowadays, sheet metal forming processes design is not a trivial task due to the complex issues to be taken into account (conflicting design goals, complex shapes forming and so on). Optimization methods have also been widely applied in sheet metal forming. Therefore, proper design methods to reduce time and costs have to be developed mostly based on computer aided procedures. At the same time, the existence of variations during manufacturing processes significantly may influence final product quality, rendering non-robust optimal solutions. In this paper, a small size of design of experiments is conducted to investigate how a stochastic behavior of noise factors affects drawing quality. The finite element software (LS_DYNA) is used to simulate the complex sheet metal stamping processes. The Kriging metamodel is adopted to map the relation between input process parameters and part quality. Robust design models for sheet metal forming process integrate adaptive importance sampling with Kriging model, in order to minimize impact of the variations and achieve reliable process parameters. In the adaptive sample, an improved criterion is used to provide direction in which additional training samples can be added to better the Kriging model. Nonlinear functions as test functions and a square stamping example (NUMISHEET'93) are employed to verify the proposed method. Final results indicate application feasibility of the aforesaid method proposed for multi-response robust design.

  5. Electrolytic process for preparing uranium metal

    DOEpatents

    Haas, Paul A.

    1990-01-01

    An electrolytic process for making uranium from uranium oxide using Cl.sub.2 anode product from an electrolytic cell to react with UO.sub.2 to form uranium chlorides. The chlorides are used in low concentrations in a melt comprising fluorides and chlorides of potassium, sodium and barium in the electrolytic cell. The electrolysis produces Cl.sub.2 at the anode that reacts with UO.sub.2 in the feed reactor to form soluble UCl.sub.4, available for a continuous process in the electrolytic cell, rather than having insoluble UO.sub.2 fouling the cell.

  6. METAL ATTENUATION PROCESSES AT MINING SITES

    EPA Science Inventory

    The purpose of this Issue Paper is to provide scientists and engineers responsible for assessing remediation technologies with background information on MNA processes at mining-impacted sites. The global magnitude of the acid drainage problem is clear evidence that in most cases...

  7. Magnetic process for removing heavy metals from water employing magnetites

    DOEpatents

    Prenger, F. Coyne; Hill, Dallas D.

    2006-12-26

    A process for removing heavy metals from water is provided. The process includes the steps of introducing magnetite to a quantity of water containing heavy metal. The magnetite is mixed with the water such that at least a portion of, and preferably the majority of, the heavy metal in the water is bound to the magnetite. Once this occurs the magnetite and absorbed metal is removed from the water by application of a magnetic field. In most applications the process is achieved by flowing the water through a solid magnetized matrix, such as steel wool, such that the magnetite magnetically binds to the solid matrix. The magnetized matrix preferably has remnant magnetism, but may also be subject to an externally applied magnetic field. Once the magnetite and associated heavy metal is bound to the matrix, it can be removed and disposed of, such as by reverse water or air and water flow through the matrix. The magnetite may be formed in-situ by the addition of the necessary quantities of Fe(II) and Fe(III) ions, or pre-formed magnetite may be added, or a combination of seed and in-situ formation may be used. The invention also relates to an apparatus for performing the removal of heavy metals from water using the process outlined above.

  8. Magnetic process for removing heavy metals from water employing magnetites

    DOEpatents

    Prenger, F. Coyne; Hill, Dallas D.; Padilla, Dennis D.; Wingo, Robert M.; Worl, Laura A.; Johnson, Michael D.

    2003-07-22

    A process for removing heavy metals from water is provided. The process includes the steps of introducing magnetite to a quantity of water containing heavy metal. The magnetite is mixed with the water such that at least a portion of, and preferably the majority of, the heavy metal in the water is bound to the magnetite. Once this occurs the magnetite and absorbed metal is removed from the water by application of a magnetic field. In most applications the process is achieved by flowing the water through a solid magnetized matrix, such as steel wool, such that the magnetite magnetically binds to the solid matrix. The magnetized matrix preferably has remnant magnetism, but may also be subject to an externally applied magnetic field. Once the magnetite and associated heavy metal is bound to the matrix, it can be removed and disposed of, such as by reverse water or air and water flow through the matrix. The magnetite may be formed in-situ by the addition of the necessary quantities of Fe(II) and Fe(III) ions, or pre-formed magnetite may be added, or a combination of seed and in-situ formation may be used. The invention also relates to an apparatus for performing the removal of heavy metals from water using the process outlined above.

  9. Applications of molten salts in reactive metals processing

    SciTech Connect

    Mishra, B.; Olson, D.L.; Averill, W.A.

    1993-12-31

    Pyrochemical processes using molten salts provide a unique opportunity for the extraction and refining of many reactive and valuable metals either directly from the beneficiated ore or from other process effluent that contain reactive metal compounds. This research program is aimed at developing a process for the production and recovery of reactive and valuable metals, such as zinc, tin, lead, bismuth and silver, in a hybrid reactor combining electrolytic production of the calcium reductant and in-situ utilization of this reductant for pyrochemical reduction of the metal compounds, such as halide or oxides. The process is equally suitable for producing other low melting metals, such as cadmium and antimony. The cell is typically operated below 1000C temperature. Attempts have been made to produce silver, lead, bismuth, tin and cerium by calciothermic reduction in a molten salt media. In a separate effort, calcium has been produced by an electrolytic dissociation of lime in a calcium chloride medium. The most important characteristic of the hybrid technology is its ability to produce metals under ``zero-waste`` conditions.

  10. Application of molten salts in pyrochemical processing of reactive metals

    SciTech Connect

    Mishra, B.; Olson, D.L. . Kroll Inst. for Extractive Metallurgy); Averill, W.A. . Rocky Flats Plant)

    1992-01-01

    Various mixes of chloride and fluoride salts are used as the media for conducting pyrochemical processes in the production and purification of reactive metals. These processes generate a significant amount of contaminated waste that has to be treated for recycling or disposal. Molten calcium chloride based salt systems have been used in this work to electrolytically regenerate calcium metal from calcium oxide for the in situ reduction of reactive metal oxides. The recovery of calcium is characterized by the process efficiency to overcome back reactions in the electrowinning cell. A thermodynamic analysis, based on fundamental rate theory, has been performed to understand the process parameters controlling the metal deposition, rate, behavior of the ceramic anode-sheath and influence of the back-reactions. It has been observed that the deposition of calcium is dependent on the ionic diffusion through the sheath. It has also been evidenced that the recovered calcium is completely lost through the back-reactions in the absence of a sheath. A practical scenario has also been presented where the electrowon metal can be used in situ as a reductant to reduce another reactive metal oxide.

  11. Primary effects of metals on osmoregulatory processes

    SciTech Connect

    DiBona, D.R.; Kendall, L.K.; Ferreria, H.G.; Bergman, H.L.

    1995-12-31

    Isolated skins of the bullfrog, Rana catesbiana, were chamber-mounted as sheets, bathed on the inside (serosa) with a Ringer`s solution but on the outside with simulations of freshwater to mimic environmental conditions. An automatic voltage-clamping protocol measured short-circuit current (I{sub sc}), an index of transepithelial Na{sup +} transport, and total tissue conductance (G{sub t}). Aluminum, cadmium, chromium, copper, lead, mercury and zinc were studied separately as additives to the outer bath and yielded qualitatively similar results. Al has been most thoroughly examined. At 200 ppB (7.4 {micro}M) or more, and at pH 5.0 or below, Al inhibits both I{sub sc} and G{sub t}. Effects are precluded by the addition of amiloride, a diuretic that blocks Na{sup +} transport at the level of the Na{sup +} channel. Kinetic analysis reveals that Al and amiloride compete for a single binding site on the channel protein. At levels of 10 ppM, Al addition results in amiloride-insensitive increases in G{sub t} (10-fold or more) and I{sub sc} (20+ {micro}A/cm{sup 2}). Isotopic flux measurements suggest that these effects are due to an ``opening`` of epithelial tight junctions with passive, downhill diffusion of salt from inside to outside; the polarity of the resulting current reflects enhanced paracellular permeability with specificity for Cl{sup {minus}} over Na{sup +}. Varying medium pH indicates that Al{sup 3+} is the dominant species in each of the two effects. Al addition to the inner bathing medium was without effect despite access to the Na{sup +}-K{sup +}-ATPase. Contaminant metals may interfere with osmoregulation by impairing salt accumulation and by enlarging leak pathways through which solutes are lost to the environment.

  12. Characterization of Transport and Solidification in the Metal Recycling Processes

    SciTech Connect

    M. A. Ebadian; R. C. Xin; Z. F. Dong

    1997-08-06

    The characterization of the transport and solidification of metal in the melting and casting processes is significant for the optimization of the radioactively contaminated metal recycling and refining processes. . In this research project, the transport process in the melting and solidification of metal was numerically predicted, and the microstructure and radionuclide distribution have been characterized by scanning electron microscope/electron diffractive X-ray (SEWEDX) analysis using cesium chloride (CSC1) as the radionuclide surrogate. In the melting and solidification process, a resistance furnace whose heating and cooling rates are program- controlled in the helium atmosphere was used. The characterization procedures included weighing, melting and solidification, weighing after solidification, sample preparation, and SEM/EDX analysis. This analytical methodology can be used to characterize metal recycling and refining products in order to evaluate the performance of the recycling process. The data obtained provide much valuable information that is necessary for the enhancement of radioactive contaminated metal decontamination and recycling technologies. The numerical method for the prediction of the melting and solidification process can be implemented in the control and monitoring system-of the melting and casting process in radioactive contaminated metal recycling. The use of radionuclide surrogates instead of real radionuclides enables the research to be performed without causing harmfid effects on people or the community. This characterization process has been conducted at the Hemispheric Center for Environmental Technology (HCET) at Florida International University since October 1995. Tests have been conducted on aluminum (Al) and copper (Cu) using cesium chloride (CSCI) as a radionuclide surrogate, and information regarding the radionuclide transfer and distribution in melting and solidification process has been obtained. The numerical simulation of

  13. Structural damage localization by outlier analysis of signal-processed mode shapes - Analytical and experimental validation

    NASA Astrophysics Data System (ADS)

    Ulriksen, M. D.; Damkilde, L.

    2016-02-01

    Contrary to global modal parameters such as eigenfrequencies, mode shapes inherently provide structural information on a local level. Therefore, this particular modal parameter and its derivatives are utilized extensively for damage identification. Typically, more or less advanced mathematical methods are employed to identify damage-induced discontinuities in the spatial mode shape signals, hereby, potentially, facilitating damage detection and/or localization. However, by being based on distinguishing damage-induced discontinuities from other signal irregularities, an intrinsic deficiency in these methods is the high sensitivity towards measurement noise. In the present paper, a damage localization method which, compared to the conventional mode shape-based methods, has greatly enhanced robustness towards measurement noise is proposed. The method is based on signal processing of a spatial mode shape by means of continuous wavelet transformation (CWT) and subsequent application of a generalized discrete Teager-Kaiser energy operator (GDTKEO) to identify damage-induced mode shape discontinuities. In order to evaluate whether the identified discontinuities are in fact damage-induced, outlier analysis is conducted by applying the Mahalanobis metric to major principal scores of the sensor-located bands of the signal-processed mode shape. The method is tested analytically and benchmarked with other mode shape-based damage localization approaches on the basis of a free-vibrating beam and validated experimentally in the context of a residential-sized wind turbine blade subjected to an impulse load.

  14. Fabrication of Metal Embedded Polymer Periodic Nanostructures by Nanoimprint Process

    NASA Astrophysics Data System (ADS)

    Ogai, Noriyuki; Sugimura, Ryo; Takiguchi, Yoshihiro

    Many nano-application research have been conducted with development of nanoimprint technologies. In particular, metal or metal-polymer hybrid nanostructures have great potentials as nano-devices such as localized surface plasmon resonance (LSPR) devices, wire grid polarizer (WGP) and organic electronics. The metal embedded polymer periodic nanostructures are also expected as a control substrate to array nanoparticles at three dimensional photonic crystal (3DPC). In this study, we propose and demonstrate new fabrication process based on a combination technique of vacuum evaporation and nanoimprint as a fabrication method for the metal embedded nanostructures. As the result, the PMMA nanodot array (approximate 100 nm in diameter with 300 nm pitch) with gold round films embedded at their bottoms were fabricated successfully using this method. Application to 3DPC and other nanodevices of these nanostructures and fabrication process are described.

  15. Electromagnetic vibration process for producing bulk metallic glasses.

    PubMed

    Tamura, Takuya; Amiya, Kenji; Rachmat, Rudi S; Mizutani, Yoshiki; Miwa, Kenji

    2005-04-01

    It is known that the cooling rate from the liquid state is an important factor in the production of bulk metallic glasses. However, the effects of other factors such as electric and magnetic fields have not been thoroughly investigated. Here, we present a new method for producing bulk metallic glasses by using electromagnetic vibrations with simultaneous imposition of an alternating electric current and a magnetic field. This method was found to be effective in enhancing apparent glass-forming ability in Mg65-Cu25-Y10 (atomic percent) alloys. Indeed, larger bulk metallic glasses could be obtained by the electromagnetic vibration process under the same cooling conditions. We presume that disappearance or decrement of clusters by the electromagnetic vibrations applied to the liquid state cause suppression of crystal nucleation. This electromagnetic vibration process should be effective in other bulk metallic glass systems if the clusters in the liquid state cause the crystal nucleation.

  16. ALKYL PYROPHOSPHATE METAL SOLVENT EXTRACTANTS AND PROCESS

    DOEpatents

    Long, R.L.

    1958-09-30

    A process is presented for the recovery of uranium from aqueous mineral acidic solutions by solvent extraction. The extractant is a synmmetrical dialkyl pyrophosphate in which the alkyl substituents have a chain length of from 4 to 17 carbon atoms. Mentioned as a preferred extractant is dioctyl pyrophosphate. The uranium is precipitated irom the organic extractant phase with an agent such as HF, fluoride salts. alcohol, or ammonia.

  17. The metallurgy and processing science of metal additive manufacturing

    DOE PAGES

    Sames, William J.; List, III, Frederick Alyious; Pannala, Sreekanth; Dehoff, Ryan R.; Babu, Sudarsanam Suresh

    2016-03-07

    Here, additive Manufacturing (AM), widely known as 3D printing, is a method of manufacturing that forms parts from powder, wire, or sheets in a process that proceeds layer-by-layer.Many techniques (using many different names) have been developed to accomplish this via melting or solid - state joining. In this review, these techniques for producing metal parts are explored, with a focus on the science of metal AM: processing defects, heat transfer, solidification, solid- state precipitation, mechanical properties, and post-processing metallurgy. The various metal AM techniques are compared, with analysis of the strengths and limitations of each. Few alloys have been developedmore » for commercial production, but recent development efforts are presented as a path for the ongoing development of new materials for AM processes.« less

  18. Removal of cadmium from metal processing wastewaters by reverse osmosis

    SciTech Connect

    Slater, C.W.; Ferrari, A.; Wisniewski, P.

    1987-01-01

    Reverse osmosis has effectively been utilized to remove cadmium from a metal processing waste stream. Experimentation with a thin-film composite membrane reduced cadmium concentrations from 165 to 0.003 mg/L under optional processing conditions. Concentrations of other metals and overall conductivity were rejected in excess of 98%. Rejection efficiency and production rate were increased by an increase in system operating pressure. Cadmium was effectively concentrated in a batch concentration study while generating high quality water for process reuse. Membrane fouling is a problem if proper in-line prefiltration is not utilized. Reverse osmosis appears to be an effective alternative to other more traditional treatment methodologies.

  19. A Calculation Method of Induction Heating Processes in Magnetic Metals

    NASA Astrophysics Data System (ADS)

    Obata, Shuji

    Various phenomena in induction heating of magnetic metals are investigated by using a multi-physics simulation method. A new theoretical treatment of kHz frequency magnetic permeability including the hysteresis characteristics is proposed to calculate the induction heating (IH) processes in magnetic metals. The complex phenomena of skin effects, heat emission, resistivity and magnetization in the heated metals are investigated, where the devised methods are applicable to various magnetic investigations. An estimation method is proposed as the retarded-trace method for analyzing the time dependent B-H characteristics.

  20. A thermolysis approach to simultaneously achieve crystal phase- and shape-control of ternary M-Fe-O metal oxide nanoparticles.

    PubMed

    Huang, Chih-Chia; Chang, Chich-Neng; Yeh, Chen-Sheng

    2011-10-01

    Significant studies have achieved beautiful control in particle size, while the shape- and phase-control synthesis of nanoparticles remains an open challenge. In this study, we have developed a generalized methodology to selectively prepare either NaCl-type (reduced form) or spinel-type ferrite (oxidized form) M-Fe-O (M = Mn, Co) crystallites with high reproducibility. A two-step heating process was able to control formation of two types of crystal phase, either a thermodynamic spinel-type under air or a kinetic-control of NaCl-type (rock salt structure) under Ar in a cubic morphology. On the other hand, the three-step heating procedure in air obtained the spinel-type with a thermodynamic equilibrium octahedral shape exclusively. Either using metal acetates (M(ac)(2)) or metal acetylacetonates (M(acac)(2)) as the starting precursors (M = Mn, Co) can be introduced to prepare NaCl-type (reduced form) or spinel-type ferrite (oxidized form) crystallites with identical experimental parameters, including precursor concentration, reaction temperature, reaction time, and heating rate. The oleic acid molecule, reaction temperature, and heating rate employed in the synthesis were carefully examined and found acting as determined roles behind the reaction processes. Apart from the previous literature reports as shape-directed and/or stabilizing agents, the oleic acid molecule played an additional phase-tuning role.

  1. Process for removing heavy metal compounds from heavy crude oil

    DOEpatents

    Cha, Chang Y.; Boysen, John E.; Branthaver, Jan F.

    1991-01-01

    A process is provided for removing heavy metal compounds from heavy crude oil by mixing the heavy crude oil with tar sand; preheating the mixture to a temperature of about 650.degree. F.; heating said mixture to up to 800.degree. F.; and separating tar sand from the light oils formed during said heating. The heavy metals removed from the heavy oils can be recovered from the spent sand for other uses.

  2. Numerical simulation on multi-gripper stretch forming process for sheet metal

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Li, M. Z.; Peng, H. L.; Gu, S. H.

    2013-05-01

    Multi-gripper stretch forming (MGSF) is a new flexible forming process compared to traditional stretching forming process. Two kinds of MGSF process, back-vertical drawing (BVD) and front-vertical drawing (FVD) are compared in this study. Spherical-curved part is selected as the research object, and the finite numerical modes for BVD and FVD have been established, and the simulation results are carried out by dynamic explicit finite element analysis. The numerical results indicated that the sheet metal can get the shape of the die at a lower strain ratio and the stretch strain distribution was more uniform by the FVD, which can improve the forming quality of the formed parts. In addition, the sheet metal can be formed by FVD under smaller hydraulic cylinder strokes. The results may provide useful guidance on optimizing the MGSF equipment structure.

  3. Alkali metal ion induced cube shaped mesoporous hematite particles for improved magnetic properties and efficient degradation of water pollutants.

    PubMed

    Roy, Mouni; Naskar, Milan Kanti

    2016-07-27

    Mesoporous cube shaped hematite (α-Fe2O3) particles were prepared using FeCl3 as an Fe(3+) precursor and 1-butyl-3-methylimidazolium bromide (ionic liquid) as a soft template in the presence of different alkali metal (lithium, sodium and potassium) acetates, under hydrothermal conditions at 150 °C/4 h followed by calcination at 350 °C. The formation of the α-Fe2O3 phase in the synthesized samples was confirmed by XRD, FTIR and Raman spectroscopy. Unlike K(+) ions, intercalation of Li(+) and Na(+) ions occurred in α-Fe2O3 crystal layers as evidenced by XRD and Raman spectroscopy. Electron microscopy (FESEM and TEM) images showed the formation of cube-like particles of different sizes in the presence of Li(+), Na(+) and K(+) ions. The mesoporosity of the products was confirmed by N2 adsorption-desorption studies, while their optical properties were analyzed by UV-DRS. Na(+) ion intercalated α-Fe2O3 microcubes showed improved coercivity (5.7 kOe) due to increased strain in crystals, and shape and magnetocrystalline anisotropy. Temperature dependent magnetization of the samples confirmed the existence of Morin temperature in the range of 199-260 K. Catalytic degradation of methylene blue (MB), a toxic water pollutant, was studied using the synthesized products via a heterogeneous photo-Fenton process. The degradation products were traced by electrospray ionization-mass spectrometry (ESI-MS). The α-Fe2O3 microcubes obtained in the presence of Na(+) ions exhibited a more efficient degradation of MB to non-toxic open chain products. PMID:27406648

  4. Investigation Of Tailored Blank Production By The Process Class Sheet-Bulk Metal Forming

    NASA Astrophysics Data System (ADS)

    Merklein, M.; Opel, S.

    2011-01-01

    Nowadays efforts are made to improve sheet metal manufacturing processes and forming capability. Functional sheet metal components, for example toothed synchronizer rings, show closely-tolerated complex geometric features, especially in the automotive industry. Unfortunately sheet metal forming operations do not offer the possibility for complex shapes as do for example cutting technologies [1]. To avoid this restriction, the usage of semi-finished products with a material pre-distribution in the blank is investigated. So-called tailored blanks are usually made of different materials or sheet thicknesses. A common way of joining diverse blanks is welding [2]. In most cases the joining has a significant influence on the consecutively forming process due to varying local mechanical properties [3]. Hence the manufacturing of tailored blanks with a defined sheet thickness characteristic by the process class "sheet-bulk metal forming" is investigated. Subsequent the tailored blanks are provided for forming operations such as deep-drawing and the direct forming of complex functional shape elements. Aim of the project is the manufacturing of circular blanks with a sheet thickening in the exterior area by an upsetting operation. At the beginning, FE-based studies and physical experiments using blanks of DC04 are carried out, to create a fundamental knowledge base of the forming process. A comparatively large contact area between blank and forming tool, a three-dimensional material flow and the low sheet thickness cause high process forces. Building up a multi-stage upsetting process with different sequenced tool geometries is one approach to meet this challenge. The material flow out of the sheet center is realized step-by-step to lower the actual contact area and sequential the appearing forces.

  5. Process for recovering alkali metals and sulfur from alkali metal sulfides and polysulfides

    DOEpatents

    Gordon, John Howard; Alvare, Javier

    2016-10-25

    Alkali metals and sulfur may be recovered from alkali monosulfide and polysulfides in an electrolytic process that utilizes an electrolytic cell having an alkali ion conductive membrane. An anolyte solution includes an alkali monosulfide, an alkali polysulfide, or a mixture thereof and a solvent that dissolves elemental sulfur. A catholyte includes molten alkali metal. Applying an electric current oxidizes sulfide and polysulfide in the anolyte compartment, causes alkali metal ions to pass through the alkali ion conductive membrane to the catholyte compartment, and reduces the alkali metal ions in the catholyte compartment. Liquid sulfur separates from the anolyte solution and may be recovered. The electrolytic cell is operated at a temperature where the formed alkali metal and sulfur are molten.

  6. Extreme Metal Music and Anger Processing

    PubMed Central

    Sharman, Leah; Dingle, Genevieve A.

    2015-01-01

    The claim that listening to extreme music causes anger, and expressions of anger such as aggression and delinquency have yet to be substantiated using controlled experimental methods. In this study, 39 extreme music listeners aged 18–34 years were subjected to an anger induction, followed by random assignment to 10 min of listening to extreme music from their own playlist, or 10 min silence (control). Measures of emotion included heart rate and subjective ratings on the Positive and Negative Affect Scale (PANAS). Results showed that ratings of PANAS hostility, irritability, and stress increased during the anger induction, and decreased after the music or silence. Heart rate increased during the anger induction and was sustained (not increased) in the music condition, and decreased in the silence condition. PANAS active and inspired ratings increased during music listening, an effect that was not seen in controls. The findings indicate that extreme music did not make angry participants angrier; rather, it appeared to match their physiological arousal and result in an increase in positive emotions. Listening to extreme music may represent a healthy way of processing anger for these listeners. PMID:26052277

  7. A novel smart rotor support with shape memory alloy metal rubber for high temperatures and variable amplitude vibrations

    NASA Astrophysics Data System (ADS)

    Ma, Yanhong; Zhang, Qicheng; Zhang, Dayi; Scarpa, Fabrizio; Liu, Baolong; Hong, Jie

    2014-12-01

    The work describes the design, manufacturing and testing of a smart rotor support with shape memory alloy metal rubber (SMA-MR) elements, able to provide variable stiffness and damping characteristics with temperature, motion amplitude and excitation frequency. Differences in damping behavior and nonlinear stiffness between SMA-MR and more traditional metal rubber supports are discussed. The mechanical performance shown by the prototype demonstrates the feasibility of using the SMA-MR concept for active vibration control in rotordynamics, in particular at high temperatures and large amplitude vibrations.

  8. Experimental simulation of a liquid-metal heat-transfer fluid flow in a T-shaped mixer

    NASA Astrophysics Data System (ADS)

    Kashinskii, O. N.; Lobanov, P. D.; Kurdyumov, A. S.; Pribaturin, N. A.

    2016-05-01

    The structure of the temperature field in a liquid-metal heat-transfer fluid flowing through a T-shaped mixer is studied experimentally. The experiments are carried out using Rose's alloy as a working fluid. To find the temperature distribution over the wall of a working section, IR thermography is applied. It is shown that the wall temperature distribution in the zone where fluid flows with different temperatures mix is heavily nonuniform. The temperature distribution substantially depends on the ratio between the hot and cold fluid flow rates. The results can be used to verify the thermal hydraulic computational codes for fluid metal flows.

  9. Statistical inference methods for recurrent event processes with shape and size parameters

    PubMed Central

    WANG, MEI-CHENG; HUANG, CHIUNG-YU

    2015-01-01

    Summary This paper proposes a unified framework to characterize the rate function of a recurrent event process through shape and size parameters. In contrast to the intensity function, which is the event occurrence rate conditional on the event history, the rate function is the occurrence rate unconditional on the event history, and thus it can be interpreted as a population-averaged count of events in unit time. In this paper, shape and size parameters are introduced and used to characterize the association between the rate function λ(·) and a random variable X. Measures of association between X and λ(·) are defined via shape- and size-based coefficients. Rate-independence of X and λ(·) is studied through tests of shape-independence and size-independence, where the shape-and size-based test statistics can be used separately or in combination. These tests can be applied when X is a covariable possibly correlated with the recurrent event process through λ(·) or, in the one-sample setting, when X is the censoring time at which the observation of N(·) is terminated. The proposed tests are shape- and size-based, so when a null hypothesis is rejected, the test results can serve to distinguish the source of violation. PMID:26412863

  10. Growth of epitaxial silicon nanowires on a Si substrate by a metal-catalyst-free process

    PubMed Central

    Ishiyama, Takeshi; Nakagawa, Shuhei; Wakamatsu, Toshiki

    2016-01-01

    The growth of epitaxial Si nanowires by a metal-catalyst-free process has been investigated as an alternative to the more common metal-catalyzed vapor–liquid–solid process. The well-aligned Si nanowires are successfully grown on a (111)-oriented Si substrate without any metal catalysts by a thermal treatment using silicon sulfide as a Si source at approximately 1200 °C. The needle-shaped Si nanowires, which have a core–shell structure that consists of a single-crystalline Si core along the <111> direction consistent with the substrate direction and a surface coating of silicon oxide, are grown by a metal-catalyst-free process. In this process, the silicon sulfide in the liquid phase facilitates the nucleation and nanowire growth. In contrast, oxygen-rich nanowires that consist of crystalline Si at the tip and lumpy silicon oxide on the body are observed in a sample grown at 1300 °C, which disturbs the epitaxial growth of Si nanowires. PMID:27465800

  11. Growth of epitaxial silicon nanowires on a Si substrate by a metal-catalyst-free process.

    PubMed

    Ishiyama, Takeshi; Nakagawa, Shuhei; Wakamatsu, Toshiki

    2016-07-28

    The growth of epitaxial Si nanowires by a metal-catalyst-free process has been investigated as an alternative to the more common metal-catalyzed vapor-liquid-solid process. The well-aligned Si nanowires are successfully grown on a (111)-oriented Si substrate without any metal catalysts by a thermal treatment using silicon sulfide as a Si source at approximately 1200 °C. The needle-shaped Si nanowires, which have a core-shell structure that consists of a single-crystalline Si core along the <111> direction consistent with the substrate direction and a surface coating of silicon oxide, are grown by a metal-catalyst-free process. In this process, the silicon sulfide in the liquid phase facilitates the nucleation and nanowire growth. In contrast, oxygen-rich nanowires that consist of crystalline Si at the tip and lumpy silicon oxide on the body are observed in a sample grown at 1300 °C, which disturbs the epitaxial growth of Si nanowires.

  12. Growth of epitaxial silicon nanowires on a Si substrate by a metal-catalyst-free process

    NASA Astrophysics Data System (ADS)

    Ishiyama, Takeshi; Nakagawa, Shuhei; Wakamatsu, Toshiki

    2016-07-01

    The growth of epitaxial Si nanowires by a metal-catalyst-free process has been investigated as an alternative to the more common metal-catalyzed vapor–liquid–solid process. The well-aligned Si nanowires are successfully grown on a (111)-oriented Si substrate without any metal catalysts by a thermal treatment using silicon sulfide as a Si source at approximately 1200 °C. The needle-shaped Si nanowires, which have a core–shell structure that consists of a single-crystalline Si core along the <111> direction consistent with the substrate direction and a surface coating of silicon oxide, are grown by a metal-catalyst-free process. In this process, the silicon sulfide in the liquid phase facilitates the nucleation and nanowire growth. In contrast, oxygen-rich nanowires that consist of crystalline Si at the tip and lumpy silicon oxide on the body are observed in a sample grown at 1300 °C, which disturbs the epitaxial growth of Si nanowires.

  13. Effects of digestion protocols on the isolation and characterization of metal-metal wear particles. I. Analysis of particle size and shape.

    PubMed

    Catelas, I; Bobyn, J D; Medley, J B; Krygier, J J; Zukor, D J; Petit, A; Huk, O L

    2001-06-01

    Isolation of metal wear particles from hip simulator lubricants or tissues surrounding implants is a challenging problem because of small particle size, their tendency to agglomerate, and their potential for chemical degradation by digestion reagents. To provide realistic measurements of size, shape, and composition of metal wear particles, it is important to optimize particle isolation and minimize particle changes due to the effects of the reagents. In this study (Part I of II), transmission electron microscopy (TEM) was used to examine and compare the effects of different isolation protocols, using enzymes or alkaline solutions, on the size and shape of three different types of cobalt-based alloy particles produced from metal-metal bearings. The effect on particle composition was examined in a subsequent study (Part II). Large particles (<1200 nm) were generated by dry abrasion of CoCrMo alloy against itself and small particles (<300 nm) were generated by hip simulator testing of a metal-metal implant pair in the presence of either distilled-deionized water or a 95% bovine serum solution. The reagents changed particle size and to a lesser extent particle shape. For both large particles and small particles generated in water, the changes in size were more extensive after alkaline than after enzymatic protocols and increased with alkaline concentration and time in solution, up to twofold at 2 h and threefold at 48 h. However, when isolating particles from 95% serum, an initial protective effect of serum proteins and/or lipids was observed. Because of this protective effect, there was no significant difference in particle size and shape for both oval and needle-shaped particles after 2 h in 2N KOH and after enzymatic treatments. However, round particles were significantly smaller after 2 h in 2N KOH than after enzymatic treatments. Particle composition may also have been affected by the 2N KOH treatment, as suggested by a difference in particle contrast under TEM

  14. Reaction-Forming Method for Producing Near Net-Shape Refractory Metal Carbides

    SciTech Connect

    Palmisiano, Marc N.; Jakubenas, Kevin J.; Baranwal, Rita

    2004-07-20

    A method for reaction forming refractory metal carbides. The method involves the fabrication of a glassy carbon preform by casting an organic, resin-based liquid mixture into a mold and subsequently heat treating it in two steps, which cures and pyrolizes the resin resulting in a porous carbon preform. By varying the amounts of the constituents in the organic, resin-based liquid mixture, control over the density of the carbon preform is obtained. Control of the density and microstructure of the carbon preform allows for determination of the microstructure and properties of the refractory metal carbide material produced. The glassy carbon preform is placed on a bed of refractory metal or refractory metal--silicon alloy. The pieces are heated above the melting point of the metal or alloy. The molten metal wicks inside the porous carbon preform and reacts, forming the refractory metal carbide or refractory metal carbide plus a minor secondary phase.

  15. Advanced method and processing technology for complicated shape airframe part forming

    NASA Technical Reports Server (NTRS)

    Miodushevsky, P. V.; Rajevskaya, G. A.

    1994-01-01

    Slow deformation modes of forming give considerably higher residual fatigue life of the airframe part. It has experimentally proven that fatigue life of complicated shape integral airframe panels made of high strength aluminum alloys is significantly increased after creep deformation process. To implement the slow deformation mode forming methods, universal automated equipment was developed. Multichannel forming systems provide high accuracy of airframe part shape eliminating residual stresses and spring effect. Forming process multizone control technology was developed and experimentally proved that static/fatigue properties of formed airframe parts are increased.

  16. [Work injuries in building construction, metal shaping, and food production sectors in Jericho District in the Palestinian territory].

    PubMed

    Al-Khatib, A; Maqdadi, R; Habash, R; Aliyan, G; Khofash, F; Grayesh, S

    2005-01-01

    Work injuries and accidents have a considerable impact on public and community health. This study targeted three work sectors: metal shaping, food production and building construction. Work injuries that occurred in these sectors were compared for the years 1999 and 2000 in Jericho District in the West Bank of Palestine. One hundred three injuries were examined and information recorded about the nature of the injury, site of injury in the body, direct cause of injury and some personal information about the injured worker. The most vulnerable group were young people in their twenties, and mostly those working in the metal shaping and building construction sectors. The kinds and sites of injuries varied. The data were compared with data from 1997, 1998 and 2001-2003, although only loosley as the available data about work injuries for these years were limited and inaccurate.

  17. Elemental Metals or Oxides Distributed on a Carbon Substrate or Self-Supported and the Manufacturing Process Using Graphite Oxide as Template

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh (Inventor)

    1999-01-01

    A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen. This intermediary product can be further processed by direct exposure to carbonate-solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

  18. Numerical analysis of the effect of the TEM{sub 00} radiation mode polarisation on the cut shape in laser cutting of thick metal sheets

    SciTech Connect

    Zaitsev, A V; Kovalev, O B; Orishich, Anatolii M; Fomin, V M

    2005-02-28

    The effect of polarisation of a Gaussian beam on the radiation absorption during laser cutting of metals is investigated. A generalised formula is proposed for calculating the absorption coefficient, which describes the polarisation of three types (linear, elliptical, and circular), taking into account the fact that the beam may interact with a metal surface of an arbitrary shape. A comparison with the existing analogues (in the cases of linear and circular radiation polarisation) confirmed the advantage of employing the formula for the spatial description of the shape of the surface produced, which is highly important for processing (cutting, welding, drilling) of thick materials. The effect of laser radiation characteristics on the surface shape and cut depth in cutting stainless steel sheets is investigated numerically. It is shown for the first time that the cutting of materials by the TEM{sub 00} beam is most efficient when the beam has elliptical polarisation directed along the direction of beam displacement and characterised by a specific axial ratio. (laser applications and other topics in quantum electronics)

  19. A fabrication method of unique Nafion® shapes by painting for ionic polymer–metal composites

    NASA Astrophysics Data System (ADS)

    Trabia, Sarah; Hwang, Taeseon; Kim, Kwang J.

    2016-08-01

    Ionic polymer–metal composites (IPMC) are useful actuators because of their ability to be fabricated in different shapes and move in various ways. However, producing unique or intricate shapes can be difficult based upon the current fabrication techniques. Presented here is a fabrication method of producing the Nafion® membrane or thin film through a painting method. Using an airbrush, a Nafion water dispersion is sprayed onto an acrylonitrile butadiene styrene surface with a stencil of the desired shape. To verify that this method of fabrication produces a Nafion membrane similar to that which is commercially available, a sample that was made using the painting method and Nafion 117 purchased from DuPont™ were tested for various characteristics and compared. The results show promising similarities. The painted Nafion sample was chemically plated with platinum and compared with a traditional IPMC for its displacement and blocking force capabilities. The painted IPMC sample showed comparable results.

  20. Use of shutdown of the capacitive storage in implementing electrical action on metallic shaped-charge jets

    NASA Astrophysics Data System (ADS)

    Fedorov, S. V.

    2016-03-01

    Tto improve the efficiency of electrical action on metallic shaped-charge jets, it is proposed to use shutdown of the capacitive storage at the time when the voltage on it during passage of an alternating discharge becomes zero. It has been shown that using this expedient eliminates recharging of the capacitive storage and provides better matching between the current pulse and the time of motion of various parts of the shaped-charge jet through the electrode gap. Studies have been conducted using a computational procedure in which the development of magnetohydrodynamic instability of the jet and the dispersion of its material are considered possible physical mechanisms reducing the penetration capability of shaped-charge jets under the action of high current pulses.

  1. A fabrication method of unique Nafion® shapes by painting for ionic polymer-metal composites

    NASA Astrophysics Data System (ADS)

    Trabia, Sarah; Hwang, Taeseon; Kim, Kwang J.

    2016-08-01

    Ionic polymer-metal composites (IPMC) are useful actuators because of their ability to be fabricated in different shapes and move in various ways. However, producing unique or intricate shapes can be difficult based upon the current fabrication techniques. Presented here is a fabrication method of producing the Nafion® membrane or thin film through a painting method. Using an airbrush, a Nafion water dispersion is sprayed onto an acrylonitrile butadiene styrene surface with a stencil of the desired shape. To verify that this method of fabrication produces a Nafion membrane similar to that which is commercially available, a sample that was made using the painting method and Nafion 117 purchased from DuPont™ were tested for various characteristics and compared. The results show promising similarities. The painted Nafion sample was chemically plated with platinum and compared with a traditional IPMC for its displacement and blocking force capabilities. The painted IPMC sample showed comparable results.

  2. Process for making surfactant capped metal oxide nanocrystals, and products produced by the process

    DOEpatents

    Alivisatos, A. Paul; Rockenberger, Joerg

    2006-01-10

    Disclosed is a process for making surfactant capped nanocrystals of metal oxides which are dispersable in organic solvents. The process comprises decomposing a metal cupferron complex of the formula MXCupX, wherein M is a metal, and Cup is a N-substituted N-Nitroso hydroxylamine, in the presence of a coordinating surfactant, the reaction being conducted at a temperature ranging from about 150 to about 400.degree. C., for a period of time sufficient to complete the reaction. Also disclosed are compounds made by the process.

  3. Pyrochemical processes for the recovery of weapons grade plutonium either as a metal or as PuO{sub 2} for use in mixed oxide reactor fuel pellets

    SciTech Connect

    Colmenares, C.A.; Ebbinghaus, B.B.; Bronson, M.C.

    1995-11-03

    The authors have developed two processes for the recovery of weapons grade Pu, as either Pu metal or PuO{sub 2}, that are strictly pyrochemical and do not produce any liquid waste. Large amounts of Pu metal (up to 4 kg.), in various geometric shapes, have been recovered by a hydride/dehydride/casting process (HYDEC) to produce metal ingots of any desired shape. The three processing steps are carried out in a single compact apparatus. The experimental technique and results obtained will be described. The authors have prepared PuO{sub 2} powders from weapons grade Pu by a process that hydrides the Pu metal followed by the oxidation of the hydride (HYDOX process). Experimental details of the best way to carry out this process will be presented, as well as the characterization of both hydride and oxide powders produced.

  4. In situ remediation process using divalent metal cations

    DOEpatents

    Brady, Patrick V.; Khandaker, Nadim R.; Krumhansl, James L.; Teter, David M.

    2004-12-14

    An in situ process for treating ambient solid materials (e.g., soils, aquifer solids, sludges) by adding one or more divalent metal cations to the ambient solid material. The added divalent metal cations, such as Cu.sup.2+ or Zn.sup.2+, combine with metal oxide/hydroxides (e.g., ferric oxide/hydroxide or aluminum oxide/hydroxide) already present in the ambient solid material to form an effective sorbent material having a large number of positively-charged surface complexes that binds and immobilizes anionic contaminant species (e.g., arsenic or chromate). Divalent metal cations can be added, for example, by injecting an aqueous solution of CuSO.sub.4 into an aquifer contaminated with arsenic or chromate. Also, sludges can be stabilized against leaching of anionic contaminants through the addition of divalent metal cations. Also, an inexpensive sorbent material can be easily formed by mixing divalent metal cations with soil that has been removed from the ground.

  5. The Role of Motor Processes in Three-Dimensional Mental Rotation: Shaping Cognitive Processing via Sensorimotor Experience

    ERIC Educational Resources Information Center

    Moreau, David

    2012-01-01

    An extensive body of literature has explored the involvement of motor processes in mental rotation, yet underlying individual differences are less documented and remain to be fully understood. We propose that sensorimotor experience shapes spatial abilities such as assessed in mental rotation tasks. Elite wrestlers' and non-athletes' mental…

  6. METALS LEACHING FROM A MINERAL PROCESSING WASTE: A COLUMN STUDY

    EPA Science Inventory

    A mineral processing waste was used to study the effect of liquid to solid ratio (L/S) on the leaching behavior of metals. Leaching tests in the form of column and batch studies were carried out to investigate liquid to solid ratios ranging from 0.7 to 50. Although the waste pass...

  7. Process of forming a sol-gel/metal hydride composite

    DOEpatents

    Congdon, James W.

    2009-03-17

    An external gelation process is described which produces granules of metal hydride particles contained within a sol-gel matrix. The resulting granules are dimensionally stable and are useful for applications such as hydrogen separation and hydrogen purification. An additional coating technique for strengthening the granules is also provided.

  8. Polystannanes: processible molecular metals with defined chemical structures.

    PubMed

    Caseri, Walter

    2016-10-01

    Polystannanes are a unique class of materials as those inorganic polymers (more precisely organometallic polymers) appear to be hitherto the only characterized polymers with a backbone of covalently bound metal atoms. This review reflects the synthesis, spectroscopic characterization (in particular (119)Sn NMR and UV-vis spectroscopy), physical properties and material properties of polystannanes, and their processing into (oriented) films and fiber blends.

  9. Heavy metal effects on cellular shape changes, cleavage, and larval development of the marine gastropod mollusk, (Ilyanassa obsoleta Say)

    SciTech Connect

    Conrad, G.W.

    1988-07-01

    The spawning areas for many marine invertebrates are in intertidal zones which can be exposed to surface water run-off containing heavy metals. The cellular shape changes and cleavage patterns of Ilyanassa embryos greatly resemble those of bivalve mollusks, such as Mytilus edulis, that occur in the same intertidal areas. Determining the concentrations of heavy metals tolerated by the molluscan embryos inhabiting such clam and mussel beds therefore is of some economic significance. Moreover, such research may providedata on the heavy metal effects on the cytoskeleton. There is increasing evidence that components of the cytoskeleton, directly or indirectly, are targets for toxic agents. Polar lobe formation is a cellular shape change that resembles cytokinesis. It is seen in the fertilized eggs of many marine mollusks. Recent data with inorganic and organic Ca/sup 2 +/ antagonists suggest that both polar lobe formation and cytokinesis utilize Ca/sup 2 +/ released from sequestered, intracellular sites. Both of these cellular constrictions are associated with microfilaments and are preceded by activation steps requiring microtubules. The data presented below suggest that several heavy metals affect the microfilament-dependent steps.

  10. Carbon Nanotube Bonding Strength Enhancement Using Metal "Wicking" Process

    NASA Technical Reports Server (NTRS)

    Lamb, James L.; Dickie, Matthew R.; Kowalczyk, Robert S.; Liao, Anna; Bronikowski, Michael J.

    2012-01-01

    Carbon nanotubes grown from a surface typically have poor bonding strength at the interface. A process has been developed for adding a metal coat to the surface of carbon nano tubes (CNTs) through a wicking process, which could lead to an enhanced bonding strength at the interface. This process involves merging CNTs with indium as a bump-bonding enhancement. Classical capillary theory would not normally allow materials that do not wet carbon or graphite to be drawn into the spacings by capillary action because the contact angle is greater than 90 degrees. However, capillary action can be induced through JPL's ability to fabricate oriented CNT bundles to desired spacings, and through the use of deposition techniques and temperature to control the size and mobility of the liquid metal streams and associated reservoirs. A reflow and plasma cleaning process has also been developed and demonstrated to remove indium oxide, and to obtain smooth coatings on the CNT bundles.

  11. Capsule-shaped metallic-cavity semiconductor lasers for low-energy on-chip light sources

    NASA Astrophysics Data System (ADS)

    Tanemura, Takuo; Zhang, Baifu; Nakano, Yoshiaki

    2016-04-01

    We review our recent studies on capsule-shaped InP/InGaAs metallic-cavity lasers. By introducing an optimal curvature at the metallic sidewalls of conventional rectangular metallic lasers, the electric fields of the resonant mode are pushed effectively into the center of the mesa, which allows dramatic reduction of the plasmonic loss. The validity of the scheme is verified both numerically and experimentally. From three-dimensional finite-difference time-domain simulation and rate-equation analysis, we estimate that the threshold current can be reduced to as low as 60 μA with the effective modal volume of 0.45 μm3. Up to 4-fold increase in Q value is confirmed experimentally for the cavity structure with an optimal curvature.

  12. Effects of Gravity on Processing Heavy Metal Fluoride Fibers

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; Workman, Gary L.; Smith, Guy A.

    1997-01-01

    The effects of gravity on the crystal nucleation of heavy metal fluoride fibers have been studied in preliminary experiments utilizing NASA's KC-135 reduced gravity aircraft and a microgravity sounding rocket flight. Commercially produced fibers were heated to the crystallization temperature in normal and reduced gravity. The fibers processed in normal gravity showed complete crystallization while the fibers processed in reduced gravity did not show signs of crystallization.

  13. The transient phase eutectic process for ceramic-metal bonding

    NASA Astrophysics Data System (ADS)

    Chapman, Thomas Richard

    A new method of ceramic-metal bonding using a transient gas-metal eutectic liquid is proposed, confirmed, and investigated using nickel/copper-oxygen/alumina as a model system. A low temperature gas-metal eutectic melt may be made transient (by solidification) through interaction with a more refractory metal component providing a ceramic-metal bond with good wetting, high strength, a broad process window (relative to conventional gas-metal eutectic bonds), high thermal stability, and controlled thermoelastic stress; transport of a more active species to the ceramic interface may further improve adherence. A eutectic between the low-melting component (copper) and a gas (oxygen) forms at the interface between the refractory metal (nickel) and ceramic (alumina). This interfacial liquid wets the surfaces and promotes bonding. Because the entire copper interlayer is melted, the processing window is wider than conventional gas-metal eutectic in terms of temperature, atmosphere, and time. The liquid (Cu-O) dissolves the active, refractory component (Ni) providing transport to the interface where a refractory bond phase (NiAl2O4) forms. Interactions at temperature consume the liquid phase causing isothermal solidification. Diffusional homogenization further increases the solidus temperature of the joint. Multilayer bond structures were produced using both foils and plating. Oxygen additions were investigated using pre-oxidation of each metal and/or oxidation in-situ. The best bonds resulted from foils combining nickel pre-oxidation with a eutectic atmosphere. The oxide layer slows the oxidation kinetics of the nickel which allows eutectic liquid to form providing wetting, reaction, and adherence to the ceramic. The interfacial bond structure consists of a uniform, thin (sub-micron) reaction layer of nickel-aluminate (NiAl2 O4) spinel. Adhesion is comparable to current technologies and can exceed the ceramic strength. Typical peel failure occurs at the metal

  14. Infiltration processing of metal matrix composites using coated ceramic particulates

    NASA Astrophysics Data System (ADS)

    Leon-Patino, Carlos Alberto

    2001-07-01

    A new process was developed to fabricate particulate metal matrix composites (MMCs). The process involves three steps: (1) modifying the particulate surface by metal coating, (2) forming a particulate porous compact; and (3) introducing metal into the channel network by vacuum infiltration. MMCs with different reinforcements, volume fractions, and sizes can be produced by this technique. Powders of alumina and silicon carbide were successfully coated with nickel and copper in preparation for infiltration with molten aluminum. Electroless Ni and Cu deposition was used since it enhances the wettability of the reinforcements for composite fabrication. While Cu deposits were polycrystalline, traces of phosphorous co-deposited from the electroless bath gave an amorphous Ni-P coating. The effect of metal coating on wetting behavior was evaluated at 800°C on plain and metal-coated ceramic plates using a sessile drop technique. The metallic films eliminated the non-wetting behavior of the uncoated ceramics, leading to equilibrium contact angles in the order of 12° and below 58° for Ni and Cu coated ceramics, respectively. The spreading data indicated that local diffusion at the triple junction was the governing mechanism of the wetting process. Precipitation of intermetallic phases in the drop/ceramic interface delayed the formation of Al4C3. Infiltration with molten Al showed that the coated-particulates are suitable as reinforcing materials for fabricating MMCs, giving porosity-free components with a homogeneously distributed reinforcing phase. The coating promoted easy metal flow through the preform, compared to the non-infiltration behavior of the uncoated counterparts. Liquid state diffusion kinetics due to temperature dependent viscosity forces controlled the infiltration process. Microstructural analysis indicated the formation of intermetallic phases such as CuAl 2, in the case of Cu coating, and Ni2Al3 and NiAl 3 when Ni-coated powders were infiltrated. The

  15. Development of experimental facilities for processing metallic crystals in orbit

    NASA Technical Reports Server (NTRS)

    Duncan, Bill J.

    1990-01-01

    This paper discusses the evolution, current status, and planning for facilities to exploit the microgravity environment of earth orbit in applied metallic materials science. Space-Shuttle based facilities and some precursor flight programs are reviewed. Current facility development programs and planned Space Station furnace capabilities are described. The reduced gravity levels available in earth orbit allow the processing of metallic materials without the disturbing influence of gravitationally induced thermal convection, stratification due to density differences in sample components, or the effects of hydrostatic pressure.

  16. Effect of Size, Content and Shape of Reinforcements on the Behavior of Metal Matrix Composites (MMCs) Under Tension

    NASA Astrophysics Data System (ADS)

    Paknia, A.; Pramanik, A.; Dixit, A. R.; Chattopadhyaya, S.

    2016-08-01

    The objective of this research was to investigate the mechanical behavior of metal matrix composites (MMCs) 6061 aluminum, reinforced with silicon carbide particles, under unidirectional tensile loading by finite element analysis. The effects of particle's shape, size and content on the tensile properties of the composites were studied and compared with each other. In addition, stress and strain distributions and possible particle fracture or debonding were investigated. It was found that, among different shapes, a certain shape of reinforcement particle provided better tensile properties for MMCs and, within each shape category, composites with smaller particle size and higher particle content (20%) also showed better properties. It was also found that when the reinforcement content was 10%, the effects of shape and size of the particles were negligible. Not only interfacial length between the reinforcement and matrix materials, but also state of matrix material, due to the presence of the reinforcement particles, affected the stiffness of the MMCs. In almost all of the cases, except for MMCs with triangular particles, when the stress increased, with the increase in the applied positive displacement, the stress distributions remained unchanged.

  17. Effect of Size, Content and Shape of Reinforcements on the Behavior of Metal Matrix Composites (MMCs) Under Tension

    NASA Astrophysics Data System (ADS)

    Paknia, A.; Pramanik, A.; Dixit, A. R.; Chattopadhyaya, S.

    2016-10-01

    The objective of this research was to investigate the mechanical behavior of metal matrix composites (MMCs) 6061 aluminum, reinforced with silicon carbide particles, under unidirectional tensile loading by finite element analysis. The effects of particle's shape, size and content on the tensile properties of the composites were studied and compared with each other. In addition, stress and strain distributions and possible particle fracture or debonding were investigated. It was found that, among different shapes, a certain shape of reinforcement particle provided better tensile properties for MMCs and, within each shape category, composites with smaller particle size and higher particle content (20%) also showed better properties. It was also found that when the reinforcement content was 10%, the effects of shape and size of the particles were negligible. Not only interfacial length between the reinforcement and matrix materials, but also state of matrix material, due to the presence of the reinforcement particles, affected the stiffness of the MMCs. In almost all of the cases, except for MMCs with triangular particles, when the stress increased, with the increase in the applied positive displacement, the stress distributions remained unchanged.

  18. Genetic algorithm optimization of the forming process in case of a U-shaped part made from tailor welded blanks

    NASA Astrophysics Data System (ADS)

    Aurelian, Albut

    2013-05-01

    This paper presents an optimization method to minimize the springback phenomenon, which generate the main dimensional errors in case of sheet metal forming. The present work deals with numerical simulation related to draw bending and springback of U-shaped part made from tailor welded blanks. The base materials from tailor welded blanks have different springback behaviours, fact that must be taken in consideration in the optimisation process. The Dynaform 5.8.1 software was used to simulate the forming process, in which the blank holder is segmented in two parts in order to apply different holding force for each material. In this research the blank holder forces and the deformation speed take different numerical values. The factorial simulations test plan was made using the Design Experts 7.0 software to cover completely the variation domain. The part obtained after each simulation is analyzed and measured to quantify the errors caused by springback. Parameters as: angle between flange and sidewall, angle between sidewall and part bottom are recorded in a data base. The initial simulations plan together with the obtained results is used to understand the influence of the variable parameters on the springback behaviour of the U-shaped part made from tailor welded blanks. The gained knowledge is used to generate the objective function required by the genetic algorithm optimization method.

  19. Semisolid Metal Processing Techniques for Nondendritic Feedstock Production

    PubMed Central

    Mohammed, M. N.; Omar, M. Z.; Salleh, M. S.; Alhawari, K. S.; Kapranos, P.

    2013-01-01

    Semisolid metal (SSM) processing or thixoforming is widely known as a technology that involves the formation of metal alloys between solidus and liquidus temperatures. For the procedure to operate successfully, the microstructure of the starting material must consist of solid near-globular grains surrounded by a liquid matrix and a wide solidus-to-liquidus transition area. Currently, this process is industrially successful, generating a variety of products with high quality parts in various industrial sectors. Throughout the years since its inception, a number of technologies to produce the appropriate globular microstructure have been developed and applied worldwide. The main aim of this paper is to classify the presently available SSM technologies and present a comprehensive review of the potential mechanisms that lead to microstructural alterations during the preparation of feedstock materials for SSM processing. PMID:24194689

  20. Process for the production of fuels and metal values

    SciTech Connect

    Audeh, C.A.

    1983-06-28

    A process for producing liquid fuels and for recovering metal values from crude petroleum by vis-breaking the reduced crude petroleum and dealkylating the vis-broken, reduced crude by treatment with an aromatic compound and an acidic transalkylation catalyst. The liquid product from the dealkylation step is separated and the residue fraction thermally processed with coal to solubilize the coal in the aromatic residue and demetallate the residue with the coal. The coal is partly liquefied in this step and the liquefaction products, together with liquids derived from the petroleum, may be hydrotreated prior to further processing e.g., in an fcc unit. The solid residue from this step may be treated to recover the metal values, especially nickel and vanadium.

  1. Method for conducting electroless metal-plating processes

    DOEpatents

    Petit, George S.; Wright, Ralph R.

    1978-01-01

    This invention is an improved method for conducting electroless metal-plating processes in a metal tank which is exposed to the plating bath. The invention solves a problem commonly encountered in such processes: how to determine when it is advisable to shutdown the process in order to clean and/or re-passivate the tank. The new method comprises contacting the bath with a current-conducting, non-catalytic probe and, during plating operations, monitoring the gradually changing difference in electropotential between the probe and tank. It has been found that the value of this voltage is indicative of the extent to which nickel-bearing decomposition products accumulate on the tank. By utilizing the voltage to determine when shutdown for cleaning is advisable, the operator can avoid premature shutdown and at the same time avoid prolonging operations to the point that spontaneous decomposition occurs.

  2. Physiological roles of bacillithiol in intracellular metal processing.

    PubMed

    Rosario-Cruz, Zuelay; Boyd, Jeffrey M

    2016-02-01

    Glutathione (GSH) is an abundantly produced low-molecular-weight (LMW) thiol in many organisms. However, a number of Gram-positive bacteria do not produce GSH, but instead produce bacillithiol (BSH) as one of the major LMW thiols. Similar to GSH, studies have found that BSH has various roles in the cell, including protection against hydrogen peroxide, hypochlorite and disulfide stress. BSH also participates in the detoxification of thiol-reactive antibiotics and the electrophilic metabolite methylglyoxal. Recently, a number of studies have highlighted additional roles for BSH in the processing of intracellular metals. Herein, we examine the potential functions of BSH in the biogenesis of Fe-S clusters, cytosolic metal buffering and the prevention of metal intoxication. PMID:26259870

  3. Process Windows for Sheet Metal Parts based on Metamodels

    NASA Astrophysics Data System (ADS)

    Harsch, D.; Heingärtner, J.; Hortig, D.; Hora, P.

    2016-08-01

    Achieving robust production of deep drawn sheet metal parts is challenging. The fluctuations of process and material properties often lead to robustness problems. Numerical simulations are used to validate the feasibility and to detect critical regions of a part. To enhance the consistency with the real process conditions, the measured material data and the force distribution are taken into account. The simulation metamodel contains the virtual knowledge of a particular forming process, which is determined based on a series of finite element simulations with variable input parameters. Based on the metamodels, process windows can be evaluated for different parameter configurations. This helps improving the operating point search, to adjust process settings if the process becomes unstable and to visualize the influence of arbitrary parameters on the process window.

  4. Removal of heavy metal ions from oil shale beneficiation process water by ferrite process

    SciTech Connect

    Mehta, R.K.; Zhang, L.; Lamont, W.E.; Schultz, C.W.

    1991-12-31

    The ferrite process is an established technique for removing heavy metals from waste water. Because the process water resulting from oil shale beneficiation falls into the category of industrial waste water, it is anticipated that this process may turn out to be a potential viable treatment for oil shale beneficiation process water containing many heave metal ions. The process is chemoremedial because not only effluent water comply with quality standards, but harmful heavy metals are converted into a valuable, chemically stable by-product known as ferrite. These spinel ferrites have magnetic properties, and therefore can be use in applications such as magnetic marker, ferrofluid, microwave absorbing and scavenging material. Experimental results from this process are presented along with results of treatment technique such as sulfide precipitation.

  5. Removal of heavy metal ions from oil shale beneficiation process water by ferrite process

    SciTech Connect

    Mehta, R.K.; Zhang, L.; Lamont, W.E.; Schultz, C.W. . Mineral Resources Inst.)

    1991-01-01

    The ferrite process is an established technique for removing heavy metals from waste water. Because the process water resulting from oil shale beneficiation falls into the category of industrial waste water, it is anticipated that this process may turn out to be a potential viable treatment for oil shale beneficiation process water containing many heave metal ions. The process is chemoremedial because not only effluent water comply with quality standards, but harmful heavy metals are converted into a valuable, chemically stable by-product known as ferrite. These spinel ferrites have magnetic properties, and therefore can be use in applications such as magnetic marker, ferrofluid, microwave absorbing and scavenging material. Experimental results from this process are presented along with results of treatment technique such as sulfide precipitation.

  6. A Study of Thermo-mechanically Processed High Stiffness NiTiCo Shape Memory Alloy

    NASA Astrophysics Data System (ADS)

    Manjeri, R. M.; Norwich, D.; Sczerzenie, F.; Huang, X.; Long, M.; Ehrlinspiel, M.

    2016-03-01

    This work investigates a vacuum induction melted-vacuum arc re-melted (VIM-VAR) and thermo-mechanically processed ternary NiTiCo shape memory alloy. The NiTiCo ingot was hot processed to 6.35-mm-diameter coiled wire. The coiled wire was subsequently cold drawn to a final wire diameter of 0.53 mm, with interpass anneals. The wires were shape set at 450 °C for 3.5 min. After electropolishing, the wires were subjected to microstructural, thermal, and mechanical characterization studies. Microstructural analysis was performed by transmission electron microscope (TEM), thermal analyses by differential scanning calorimeter (DSC), and bend-free recovery and mechanical testing by uniaxial tensile testing. TEM did not reveal Ni-rich precipitates—either at the grain boundary or in the grain interior. Energy dispersive x-ray spectroscopy showed a uniform distribution of Ni, Ti, and Co in the sample. The DSC results on the shape set wire showed a single-step transformation between the austenite and the R-phase, in the forward and reverse directions. Cyclic tensile tests of the shape set wire, processed under optimum conditions, showed minimum residual strain and a stable upper plateau stress. Further, the fatigue behavior of NiTi and NiTiCo alloys was studied by rotating beam testing. The results showed that the fatigue properties of NiTiCo, under zero mean strain, are equivalent to that of binary NiTi in the high-cycle and medium-cycle regimes, taking into account the higher stiffness of NiTiCo. The above analyses helped in establishing the processing-structure-property correlation in a VIM-VAR-melted NiTiCo shape memory alloy.

  7. Porosity Measurements and Analysis for Metal Additive Manufacturing Process Control.

    PubMed

    Slotwinski, John A; Garboczi, Edward J; Hebenstreit, Keith M

    2014-01-01

    Additive manufacturing techniques can produce complex, high-value metal parts, with potential applications as critical metal components such as those found in aerospace engines and as customized biomedical implants. Material porosity in these parts is undesirable for aerospace parts - since porosity could lead to premature failure - and desirable for some biomedical implants - since surface-breaking pores allows for better integration with biological tissue. Changes in a part's porosity during an additive manufacturing build may also be an indication of an undesired change in the build process. Here, we present efforts to develop an ultrasonic sensor for monitoring changes in the porosity in metal parts during fabrication on a metal powder bed fusion system. The development of well-characterized reference samples, measurements of the porosity of these samples with multiple techniques, and correlation of ultrasonic measurements with the degree of porosity are presented. A proposed sensor design, measurement strategy, and future experimental plans on a metal powder bed fusion system are also presented.

  8. Porosity Measurements and Analysis for Metal Additive Manufacturing Process Control.

    PubMed

    Slotwinski, John A; Garboczi, Edward J; Hebenstreit, Keith M

    2014-01-01

    Additive manufacturing techniques can produce complex, high-value metal parts, with potential applications as critical metal components such as those found in aerospace engines and as customized biomedical implants. Material porosity in these parts is undesirable for aerospace parts - since porosity could lead to premature failure - and desirable for some biomedical implants - since surface-breaking pores allows for better integration with biological tissue. Changes in a part's porosity during an additive manufacturing build may also be an indication of an undesired change in the build process. Here, we present efforts to develop an ultrasonic sensor for monitoring changes in the porosity in metal parts during fabrication on a metal powder bed fusion system. The development of well-characterized reference samples, measurements of the porosity of these samples with multiple techniques, and correlation of ultrasonic measurements with the degree of porosity are presented. A proposed sensor design, measurement strategy, and future experimental plans on a metal powder bed fusion system are also presented. PMID:26601041

  9. Porosity Measurements and Analysis for Metal Additive Manufacturing Process Control

    PubMed Central

    Slotwinski, John A; Garboczi, Edward J; Hebenstreit, Keith M

    2014-01-01

    Additive manufacturing techniques can produce complex, high-value metal parts, with potential applications as critical metal components such as those found in aerospace engines and as customized biomedical implants. Material porosity in these parts is undesirable for aerospace parts - since porosity could lead to premature failure - and desirable for some biomedical implants - since surface-breaking pores allows for better integration with biological tissue. Changes in a part’s porosity during an additive manufacturing build may also be an indication of an undesired change in the build process. Here, we present efforts to develop an ultrasonic sensor for monitoring changes in the porosity in metal parts during fabrication on a metal powder bed fusion system. The development of well-characterized reference samples, measurements of the porosity of these samples with multiple techniques, and correlation of ultrasonic measurements with the degree of porosity are presented. A proposed sensor design, measurement strategy, and future experimental plans on a metal powder bed fusion system are also presented. PMID:26601041

  10. Role of Tool-Part Interaction in Consolidation of L-Shaped Laminates during Autoclave Process

    NASA Astrophysics Data System (ADS)

    Sun, Jing; Gu, Yizhuo; Li, Yanxia; Li, Min; Zhang, Zuoguang

    2012-06-01

    The role of tool-part interaction in the consolidation process of the L-shaped laminate was studied using a finite element model. The tool-part shear actions during processing were modeled by introducing shear layers. The predicted data demonstrate the necessity of considering the slippage between the tools and the laminate in simulations. A parametric study examining the effects of the shear layer properties on the compacting behavior was performed and the results show that improving the slippage ability of the male mold upon the composite part is of advantage to apply the pressure on the corner section of the L-shaped laminate. Moreover, the mechanical properties and the thickness of the shear layer have a significant influence on the modeling of the consolidation process.

  11. An online detection system for aggregate sizes and shapes based on digital image processing

    NASA Astrophysics Data System (ADS)

    Yang, Jianhong; Chen, Sijia

    2016-07-01

    Traditional aggregate size measuring methods are time-consuming, taxing, and do not deliver online measurements. A new online detection system for determining aggregate size and shape based on a digital camera with a charge-coupled device, and subsequent digital image processing, have been developed to overcome these problems. The system captures images of aggregates while falling and flat lying. Using these data, the particle size and shape distribution can be obtained in real time. Here, we calibrate this method using standard globules. Our experiments show that the maximum particle size distribution error was only 3 wt%, while the maximum particle shape distribution error was only 2 wt% for data derived from falling aggregates, having good dispersion. In contrast, the data for flat-lying aggregates had a maximum particle size distribution error of 12 wt%, and a maximum particle shape distribution error of 10 wt%; their accuracy was clearly lower than for falling aggregates. However, they performed well for single-graded aggregates, and did not require a dispersion device. Our system is low-cost and easy to install. It can successfully achieve online detection of aggregate size and shape with good reliability, and it has great potential for aggregate quality assurance.

  12. SOLVENT EXTRACTION PROCESS FOR SEPARATING ACTINIDE AND LANTHANIDE METAL VALUES

    DOEpatents

    Hildebrandt, R.A.; Hyman, H.H.; Vogler, S.

    1962-08-14

    A process of countercurrently extracting an aqueous mineral acid feed solution for the separation of actinides from lanthanides dissolved therern is described. The feed solution is made acid-defrcient with alkali metal hydroxide prior to.contact with acid extractant; during extraction, however, acid is transferred from organic to aqueous solution and the aqueous solution gradually becomes acid. The acid-deficient phase ' of the process promotes the extraction of the actinides, while the latter acid phase'' of the process improves retention of the lanthanides in the aqueous solution. This provides for an improved separation. (AEC)

  13. Effect of temper rolling on final shape defects in a V-section roll forming process

    NASA Astrophysics Data System (ADS)

    Abvabi, Akbar; Rolfe, Bernard; Hodgson, Peter D.; Weiss, Matthias

    2013-12-01

    Roll forming is a continuous process in which a flat strip is shaped to the desired profile by sequential bending in a series of roll stands. Because of the large variety of applications of roll forming in the industry, Finite Element Analysis (FEA) is increasingly utilized for roll forming process design. Bending is the dominant deformation mode in roll forming. Sheet materials used in this process are generally temper rolled, roller- or tension- leveled. These processes introduce residual stresses into the material, and recent studies have shown that those affect the material behavior in bending. In this study a numerical model of the temper rolling (skin passing) process was used to determine a residual stress distribution in a dual phase, DP780, steel strip. A 5-stand roll forming process for the forming of a V-section was modeled, and the effect of various thickness reduction levels in the temper rolling process on the final shape defects was analyzed. The results show that a small thickness reduction in the temper rolling process decreases the maximum bow height but the final springback angle increases. It is also shown that reasonable model accuracy can be achieved by including the residual stress information due to temper rolling as initial condition in the numerical modeling of a roll forming process.

  14. The Chemophytostabilisation Process of Heavy Metal Polluted Soil.

    PubMed

    Grobelak, Anna; Napora, Anna

    2015-01-01

    Industrial areas are characterised by soil degradation processes that are related primarily to the deposition of heavy metals. Areas contaminated with metals are a serious source of risk due to secondary pollutant emissions and metal leaching and migration in the soil profile and into the groundwater. Consequently, the optimal solution for these areas is to apply methods of remediation that create conditions for the restoration of plant cover and ensure the protection of groundwater against pollution. Remediation activities that are applied to large-scale areas contaminated with heavy metals should mainly focus on decreasing the degree of metal mobility in the soil profile and metal bioavailability to levels that are not phytotoxic. Chemophytostabilisation is a process in which soil amendments and plants are used to immobilise metals. The main objective of this research was to investigate the effects of different doses of organic amendments (after aerobic sewage sludge digestion in the food industry) and inorganic amendments (lime, superphosphate, and potassium phosphate) on changes in the metals fractions in soils contaminated with Cd, Pb and Zn during phytostabilisation. In this study, the contaminated soil was amended with sewage sludge and inorganic amendments and seeded with grass (tall fescue) to increase the degree of immobilisation of the studied metals. The contaminated soil was collected from the area surrounding a zinc smelter in the Silesia region of Poland (pH 5.5, Cd 12 mg kg-1, Pb 1100 mg kg-1, Zn 700 mg kg-1). A plant growth experiment was conducted in a growth chamber for 5 months. Before and after plant growth, soil subsamples were subjected to chemical and physical analyses. To determine the fractions of the elements, a sequential extraction method was used according to Zeien and Brümmer. Research confirmed that the most important impacts on the Zn, Cd and Pb fractions included the combined application of sewage sludge from the food industry and

  15. The Chemophytostabilisation Process of Heavy Metal Polluted Soil

    PubMed Central

    Grobelak, Anna; Napora, Anna

    2015-01-01

    Industrial areas are characterised by soil degradation processes that are related primarily to the deposition of heavy metals. Areas contaminated with metals are a serious source of risk due to secondary pollutant emissions and metal leaching and migration in the soil profile and into the groundwater. Consequently, the optimal solution for these areas is to apply methods of remediation that create conditions for the restoration of plant cover and ensure the protection of groundwater against pollution. Remediation activities that are applied to large-scale areas contaminated with heavy metals should mainly focus on decreasing the degree of metal mobility in the soil profile and metal bioavailability to levels that are not phytotoxic. Chemophytostabilisation is a process in which soil amendments and plants are used to immobilise metals. The main objective of this research was to investigate the effects of different doses of organic amendments (after aerobic sewage sludge digestion in the food industry) and inorganic amendments (lime, superphosphate, and potassium phosphate) on changes in the metals fractions in soils contaminated with Cd, Pb and Zn during phytostabilisation. In this study, the contaminated soil was amended with sewage sludge and inorganic amendments and seeded with grass (tall fescue) to increase the degree of immobilisation of the studied metals. The contaminated soil was collected from the area surrounding a zinc smelter in the Silesia region of Poland (pH 5.5, Cd 12 mg kg-1, Pb 1100 mg kg-1, Zn 700 mg kg-1). A plant growth experiment was conducted in a growth chamber for 5 months. Before and after plant growth, soil subsamples were subjected to chemical and physical analyses. To determine the fractions of the elements, a sequential extraction method was used according to Zeien and Brümmer. Research confirmed that the most important impacts on the Zn, Cd and Pb fractions included the combined application of sewage sludge from the food industry and

  16. The Chemophytostabilisation Process of Heavy Metal Polluted Soil.

    PubMed

    Grobelak, Anna; Napora, Anna

    2015-01-01

    Industrial areas are characterised by soil degradation processes that are related primarily to the deposition of heavy metals. Areas contaminated with metals are a serious source of risk due to secondary pollutant emissions and metal leaching and migration in the soil profile and into the groundwater. Consequently, the optimal solution for these areas is to apply methods of remediation that create conditions for the restoration of plant cover and ensure the protection of groundwater against pollution. Remediation activities that are applied to large-scale areas contaminated with heavy metals should mainly focus on decreasing the degree of metal mobility in the soil profile and metal bioavailability to levels that are not phytotoxic. Chemophytostabilisation is a process in which soil amendments and plants are used to immobilise metals. The main objective of this research was to investigate the effects of different doses of organic amendments (after aerobic sewage sludge digestion in the food industry) and inorganic amendments (lime, superphosphate, and potassium phosphate) on changes in the metals fractions in soils contaminated with Cd, Pb and Zn during phytostabilisation. In this study, the contaminated soil was amended with sewage sludge and inorganic amendments and seeded with grass (tall fescue) to increase the degree of immobilisation of the studied metals. The contaminated soil was collected from the area surrounding a zinc smelter in the Silesia region of Poland (pH 5.5, Cd 12 mg kg-1, Pb 1100 mg kg-1, Zn 700 mg kg-1). A plant growth experiment was conducted in a growth chamber for 5 months. Before and after plant growth, soil subsamples were subjected to chemical and physical analyses. To determine the fractions of the elements, a sequential extraction method was used according to Zeien and Brümmer. Research confirmed that the most important impacts on the Zn, Cd and Pb fractions included the combined application of sewage sludge from the food industry and

  17. Which processes shape stellar population gradients of massive galaxies at large radii?

    NASA Astrophysics Data System (ADS)

    Hirschmann, Michaela

    2016-08-01

    We investigate the differential impact of physical mechanisms, mergers (stellar accretion) and internal energetic phenomena, on the evolution of stellar population gradients in massive, present-day galaxies employing a set of high-resolution, cosmological zoom simulations. We demonstrate that negative metallicity and color gradients at large radii (>2Reff) originate from the accretion of metal-poor stellar systems. At larger radii, galaxies become typically more dominated by stars accreted from satellite galaxies in major and minor mergers. However, only strong galactic winds can sufficiently reduce the metallicity content of the accreted stars to realistically steepen the outer metallicity and colour gradients in agreement with present-day observations. In contrast, the gradients of the models without winds are inconsistent with observations (too flat). In the wind model, colour and metallicity gradients are significantly steeper for systems which have accreted stars in minor mergers, while galaxies with major mergers have relatively flat gradients, confirming previous results. This analysis greatly highlights the importance of both energetic processes and merger events for stellar population properties of massive galaxies at large radii. Our results are expected to significantly contribute to the interpretation of current and up-coming IFU surveys (like MaNGA and Califa), which in turn can help to better constrain still uncertain models for energetic processes in simulations.

  18. New spin-on metal hardmask materials for lithography processes

    NASA Astrophysics Data System (ADS)

    Yao, Huirong; Mullen, Salem; Wolfer, Elizabeth; Rahman, Dalil; Anyadiegwu, Clement; Mckenzie, Douglas; Dioses, Alberto; Cho, Joonyeon; Padmanaban, Munirathna

    2013-03-01

    Since the critical dimensions in integrated circuit (IC) device fabrication continue to shrink below 32 nm, multilayer stacks with alternating etch selectivities are required for successful pattern transfer from the exposed photoresist to the substrate. Inorganic resist underlayer materials are used as hard masks in reactive ion etching (RIE) with oxidative gases. The conventional silicon hardmask has demonstrated good reflectivity control and reasonable etch selectivity. However, some issues such as the rework of trilayer stacks and cleaning of oxide residue by wet chemistry are challenging problems for manufacturability. The present work reveals novel spin-on underlayer materials containing significant amounts of metal oxides in the film after baking at normal processing conditions. Such an inorganic metal hardmask (MHM) has excellent etch selectivity in plasma etch processes of the trilayer stack. The composition has good long term shelf life and pot life stability based on solution LPC analysis and wafer defect studies, respectively. The material absorbs DUV wavelengths and can be used as a spin-on inorganic or hybrid antireflective coating to control substrate reflectivity under DUV exposure of photoresist. Some of these metal-containing materials can be used as an underlayer in EUV lithography to significantly enhance photospeed. Specific metal hard masks are also developed for via or trench filling applications in IRT processes. The materials have shown good coating and lithography performance with a film thicknesses as low as 10 nm under ArF dry or immersion conditions. In addition, the metal oxide films or residues can be partially or completely removed by using various wet-etching solutions at ambient temperature.

  19. Development of latent fingerprints on metallic surfaces using electropolymerization processes.

    PubMed

    Bersellini, C; Garofano, L; Giannetto, M; Lusardi, F; Mori, G

    2001-07-01

    We propose a new process for developing latent fingerprints on metal items, applicable to unfired weapons made of Ergal in particular. The method is based on the presence of fatty acids that are contained in fingerprints and act as an insulator on the surface where fingerprints are to be developed. The process of polymerization occurs on the metal portions left untouched by finger contact. Hence, the developing process results as a negative pattern of the original fingerprint. The reaction consists in the electropolymerization of pyrrole and substituted porphyrins, i.e., tetra (o-aminophenyl) porphyrine: radical-cations are generated on superficial nucleation sites by oxidation of monomer, close to the electrode surface; subsequently, the radical species react with the neutral monomer, which begins to diffuse to the electrode. We have also studied the polymer's morphology by means of SEM and AFM, in order to find a correlation between the reagent to be used and the quality of the enhancement process. These are only preliminary results; however, they show that the suggested method is a new way to increase the rate of success in developing latent fingerprints on metal surfaces. In this regard, it may be considered complementary to other conventional procedures, due to the low costs of the instruments and reagents, and the rapidity and simplicity of the treatment.

  20. Research on the Signal Process of a Bell-Shaped Vibratory Angular Rate Gyro

    PubMed Central

    Su, Zhong; Liu, Ning; Li, Qing; Fu, Mengyin; Liu, Hong; Fan, Junfang

    2014-01-01

    A bell-shaped vibratory angular rate gyro, which is inspired by the Chinese traditional bell, is a kind of axisymmetric shell resonator gyroscope. Its sensitive element is a vibratory-like Chinese traditional bell, using a piezoelectric element on the wall of the vibrator to detect the standing wave's precession to solve the input angular rate. This work mainly studies the circuit system of a bell-shaped vibratory angular rate gyro. It discusses the process of circuit system design, analysis and experiment, in detail, providing the foundation to develop a bell-shaped vibratory angular rate gyro. Since the bell-shaped resonator's curved structure has the characteristics of large noise in the piezoelectric signal and large harmonics, this paper analyzes its working and signal detection method, then gives the whole plan of the circuit system, including the drive module, the detection module and the control loop. It also studies every part of the whole system, gives a detailed design and analysis process and proves part of the circuit system using digital simulation. At the end of the article, the test result of the circuit system shows that it can remove the disadvantages of the curved structure having large noise in the piezoelectric signal and large harmonics and is more effective at solving the input angular rate. PMID:24633451

  1. Ring beam shaping optics fabricated with ultra-precision cutting for YAG laser processing

    NASA Astrophysics Data System (ADS)

    Kuwano, Ryoichi; Koga, Toshihiko; Tokunaga, Tsuyoshi; Wakayama, Toshitaka; Otani, Yukitoshi; Fujii, Nobuyuki

    2012-03-01

    In this study, a method for generating ring intensity distribution at a refraction-type lens with an aspheric element was proposed, and the beam shaping optical element was finished using only ultra-precision cutting. The shape of the optical element and its irradiance pattern were determined from numerical calculation based on its geometrical and physical optics. An ultra-precision lathe was employed to fabricate beam shaping optical elements, and acrylic resin was used as the material. The transmittance of an optical element (a rotationally symmetrical body) with an aspheric surface fabricated using a single-crystal diamond tool was over 98%, and its surface roughness was 9.6 nm Ra. The method enabled the formation of a circular melting zone on a piece of stainless steel with a thickness of 300 μm through pulse YAG laser ( λ 1:06 μm) processing such that the average radius was 610 μm and the width was 100-200 μm. Circular processing using a ring beam shaping optical element can be realized by single-pulse beam irradiation without beam scanning.

  2. A thermolysis approach to simultaneously achieve crystal phase- and shape-control of ternary M-Fe-O metal oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Huang, Chih-Chia; Chang, Chich-Neng; Yeh, Chen-Sheng

    2011-10-01

    Significant studies have achieved beautiful control in particle size, while the shape- and phase-control synthesis of nanoparticles remains an open challenge. In this study, we have developed a generalized methodology to selectively prepare either NaCl-type (reduced form) or spinel-type ferrite (oxidized form) M-Fe-O (M = Mn, Co) crystallites with high reproducibility. A two-step heating process was able to control formation of two types of crystal phase, either a thermodynamic spinel-type under air or a kinetic-control of NaCl-type (rock salt structure) under Ar in a cubic morphology. On the other hand, the three-step heating procedure in air obtained the spinel-type with a thermodynamic equilibrium octahedral shape exclusively. Either using metal acetates (M(ac)2) or metal acetylacetonates (M(acac)2) as the starting precursors (M = Mn, Co) can be introduced to prepare NaCl-type (reduced form) or spinel-type ferrite (oxidized form) crystallites with identical experimental parameters, including precursor concentration, reaction temperature, reaction time, and heating rate. The oleic acid molecule, reaction temperature, and heating rate employed in the synthesis were carefully examined and found acting as determined roles behind the reaction processes. Apart from the previous literature reports as shape-directed and/or stabilizing agents, the oleic acid molecule played an additional phase-tuning role.Significant studies have achieved beautiful control in particle size, while the shape- and phase-control synthesis of nanoparticles remains an open challenge. In this study, we have developed a generalized methodology to selectively prepare either NaCl-type (reduced form) or spinel-type ferrite (oxidized form) M-Fe-O (M = Mn, Co) crystallites with high reproducibility. A two-step heating process was able to control formation of two types of crystal phase, either a thermodynamic spinel-type under air or a kinetic-control of NaCl-type (rock salt structure) under Ar in a

  3. Metal Matrix Composite LOX Turbopump Housing via Novel Tool-less Net-Shape Pressure Infiltration Casting Technology

    NASA Technical Reports Server (NTRS)

    Shah, Sandeep; Lee, Jonathan; Bhat, Biliyar; Wells, Doug; Gregg, Wayne; Marsh, Matthew; Genge, Gary; Forbes, John; Salvi, Alex; Cornie, James A.

    2003-01-01

    Metal matrix composites for propulsion components offer high performance and affordability, resulting in low weight and cost. The following sections in this viewgraph presentation describe the pressure infiltration casting of a metal matrix composite LOX turbopump housing: 1) Baseline Pump Design and Stress Analysis; 2) Tool-less Advanced Pressure Infiltration Casting Process; 3) Preform Splicing and Joining for Large Components such as Pump Housing; 4) Fullscale Pump Housing Redesign.

  4. Shape assisted fabrication of fluorescent cages of squarate based metal-organic coordination frameworks.

    PubMed

    Jayaramulu, Kolleboyina; Krishna, Katla Sai; George, Subi J; Eswaramoorthy, Muthuswamy; Maji, Tapas Kumar

    2013-05-11

    Micronic cage structures of squarate based metal-organic coordination frameworks (MOCFs) have been fabricated for the first time by specific anion selective etching of metal squarate cubes. Time and stoichiometry dependent synthesis and the corresponding microscopic studies have provided mechanistic insight into the cage formation. Furthermore, a non-covalent post-synthetic strategy has been adopted to functionalize the micronic cubes or cages with chromophores rendering the resulting hybrids green fluorescent.

  5. Laser cleaning of metal surfaces: physical processes and applications

    NASA Astrophysics Data System (ADS)

    Veiko, V. P.; Mutin, T. J.; Smirnov, V. N.; Shakhno, E. A.; Batishche, S. A.

    2008-01-01

    Physical processes occurring by laser cleaning of metal surfaces from soiling particles, coatings and near-surface oxide or corroded layer are considered. Unconventional methods of laser cleaning which promote increasing the quality and effectiveness of cleaning and solving of the problem of soiling substance gathering are proposed. Applications of these methods in a number of novel fields, such as pinholes cleaning, coatings removal, radioactive contaminated layers removal, cleaning of objects of historic and cultural heritage are considered.

  6. A Method of Springback Prediction and Tool Shape Compensation for Multi-curvature Sheet Metal Bending

    NASA Astrophysics Data System (ADS)

    Zhou, Chi; Liao, Juan; Zhu, Yin; Chen, Zhenjiao

    2010-06-01

    Advanced High Strength Steels (AHSS) are used increasingly in automobile structure parts to reduce the vehicle weight while keeping the safety standard. But their high values of the ratio of strength to Young's modulus cause more springback problems. A method of calculating the compensated tool shape for complex bending shapes is proposed in this paper. The method is composed of 3 steps: firstly the cross-section profile of a part was discretized into points and their corresponding curvatures; then an analytic algorithm based on plastic bending theory is applied to calculate the compensated curvatures of each point; finally, a numerical algorithm based on differential geometry is used to construct the tool shape according to the compensated curvatures of each point. A wave-shaped AHSS part with three different curvatures had been used to evaluate this method. The experimental results showed that the max curvature variance between the actual bending parts and desired shape is less than 4%, which is satisfying for most engineering applications.

  7. Gold and silver nanoparticles in sensing and imaging: sensitivity of plasmon response to size, shape, and metal composition.

    PubMed

    Lee, Kyeong-Seok; El-Sayed, Mostafa A

    2006-10-01

    Plasmonic metal nanoparticles have great potential for chemical and biological sensor applications, due to their sensitive spectral response to the local environment of the nanoparticle surface and ease of monitoring the light signal due to their strong scattering or absorption. In this work, we investigated the dependence of the sensitivity of the surface plasmon resonance (frequency and bandwidth) response to changes in their surrounding environment and the relative contribution of optical scattering to the total extinction, on the size and shape of nanorods and the type of metal, that is, Au vs Ag. Theoretical consideration on the surface plasmon resonance condition revealed that the spectral sensitivity, defined as the relative shift in resonance wavelength with respect to the refractive index change of surrounding materials, has two controlling factors: first the bulk plasma wavelength, a property dependent on the metal type, and second on the aspect ratio of the nanorods which is a geometrical parameter. It is found that the sensitivity is linearly proportional to both these factors. To quantitatively examine the dependence of the spectral sensitivity on the nanorod metal composition and the aspect ratio, the discrete dipole approximation method was used for the calculation of optical spectra of Ag-Au alloy metal nanorods as a function of Ag concentration. It is observed that the sensitivity does not depend on the type of the metal but depends largely on the aspect ratio of nanorods. The direct dependence of the sensitivity on the aspect ratio becomes more prominent as the size of nanorods becomes larger. However, the use of larger nanoparticles may induce an excessive broadening of the resonance spectrum due to an increase in the contribution of multipolar excitations. This restricts the sensing resolution. The insensitivity of the plasmon response to the metal composition is attributable to the fact that the bulk plasma frequency of the metal, which

  8. Self-Repairing Fatigue Damage in Metallic Structures for Aerospace Vehicles Using Shape Memory Alloy Self-healing (SMASH) Technology

    NASA Technical Reports Server (NTRS)

    Wright, M. Clara; Manuel, Michele; Wallace, Terryl; Newman, Andy; Brinson, Kate

    2015-01-01

    This DAA is for the Phase II webinar presentation of the ARMD-funded SMASH technology. A self-repairing aluminum-based composite system has been developed using liquid-assisted healing theory in conjunction with the shape memory effect of wire reinforcements. The metal matrix composite was thermodynamically designed to have a matrix with a relatively even dispersion of low-melting phase, allowing for repair of cracks at a pre-determined temperature. Shape memory alloy wire reinforcements were used within the composite to provide crack closure. Investigators focused the research on fatigue cracks propagating through the matrix in order to optimize and computer model the SMASH technology for aeronautical applications.

  9. Production of A357 motor mount bracket by the metal compression forming process

    SciTech Connect

    Viswanathan, S.; Brinkman, C.R.; Porter, W.D.; Purgert, R.M.

    1997-09-01

    The use of aluminum alloy castings for safety critical structural components such as engine mount brackets, steering knuckles, and control arms, offers significant opportunities for achieving weight reduction in automobiles, since they are typically about half the weight of the steel, cast iron, or ductile iron component that they replace. Metal Compression Forming (MCF) is a variant of the squeeze casting process, in which molten metal is allowed to solidify under pressure in order to close porosity and form a sound part. However, the MCF process applies pressure on the entire mold face, thereby directing pressure on all regions of the casting and producing a uniformly sound part. The process is capable of producing parts with properties close to those of forgings, while retaining the near net shape, complexity in geometry, and relatively low cost of the casting process. The paper describes the casting process development involved in the production of an aluminum A357 alloy motor mount bracket, including the use of a filling and solidification model to design the gating and determine process parameters. Tensile properties of the component are presented and correlated with those of forged components. Limited fatigue properties obtained by fully reversed strain controlled testing are also presented.

  10. Observation of Coalescence Process of Silver Nanospheres During Shape Transformation to Nanoprisms.

    PubMed

    Yu, Pyng; Huang, Jane; Tang, Jau

    2011-12-01

    In this report, we observed the growth mechanism and the shape transformation from spherical nanoparticles (diameter ~6 nm) to triangular nanoprisms (bisector length ~100 nm). We used a simple direct chemical reduction method and provided evidences for the growth of silver nanoprisms via a coalescence process. Unlike previous reports, our method does not rely upon light, heat, or strong oxidant for the shape transformation. This transformation could be launched by fine-tuning the pH value of the silver colloidal solution. Based on our extensive examination using transmission electron microscopy, we propose a non-point initiated growth mechanism, which is a combination of coalescence and dissolution-recrystallization process during the growth of silver nanoprisms.

  11. Scalable shape-controlled fabrication of curved microstructures using a femtosecond laser wet-etching process.

    PubMed

    Bian, Hao; Yang, Qing; Chen, Feng; Liu, Hewei; Du, Guangqing; Deng, Zefang; Si, Jinhai; Yun, Feng; Hou, Xun

    2013-07-01

    Materials with curvilinear surface microstructures are highly desirable for micro-optical and biomedical devices. However, realization of such devices efficiently remains technically challenging. This paper demonstrates a facile and flexible method to fabricate curvilinear microstructures with controllable shapes and dimensions. The method composes of femtosecond laser exposures and chemical etching process with the hydrofluoric acid solutions. By fixed-point and step-in laser irradiations followed by the chemical treatments, concave microstructures with different profiles such as spherical, conical, bell-like and parabola were fabricated on silica glasses. The convex structures were replicated on polymers by the casting replication process. In this work, we used this technique to fabricate high-quality microlens arrays and high-aspect-ratio microwells which can be used in 3D cell culture. This approach offers several advantages such as high-efficient, scalable shape-controllable and easy manipulations.

  12. [INVITED] Evaluation of process observation features for laser metal welding

    NASA Astrophysics Data System (ADS)

    Tenner, Felix; Klämpfl, Florian; Nagulin, Konstantin Yu.; Schmidt, Michael

    2016-06-01

    In the present study we show how fast the fluid dynamics change when changing the laser power for different feed rates during laser metal welding. By the use of two high-speed cameras and a data acquisition system we conclude how fast we have to image the process to measure the fluid dynamics with a very high certainty. Our experiments show that not all process features which can be measured during laser welding do represent the process behavior similarly well. Despite the good visibility of the vapor plume the monitoring of its movement is less suitable as an input signal for a closed-loop control. The features measured inside the keyhole show a good correlation with changes of process parameters. Due to its low noise, the area of the keyhole opening is well suited as an input signal for a closed-loop control of the process.

  13. Dynamic near-field nanofocusing by V-shaped metal groove via a femtosecond laser excitation

    NASA Astrophysics Data System (ADS)

    Du, Guangqing; Yang, Qing; Chen, Feng; Lu, Yu; Ou, Yan; Yong, Jiale; Hou, Xun

    2016-03-01

    The ultrafast dynamics of plasmonic near-field nanofocusing by a V-shaped groove milled on Au film via a femtosecond laser excitation is theoretically studied based on finite element method. The spatiotemporal evolution of the focused e-fields around the V-groove geometry is obtained. It is revealed that the strong nanofocusing at the V-shaped groove occurs at the moderate electron temperature of 3000 K in the electron-phonon uncoupled state via a femtosecond laser pulse excitation. The phenomenon is explained as the electron thermal dynamics manipulation of plasmon resonances due to femtosecond laser fluence modifications. This study provides basic understanding of ultrafast dynamics of near-field nanofocusing in V-shaped geometry for wide applications in the fields such as super-resolution imaging, SERS, and photothermal therapy.

  14. Three-dimensional shape measurement system applied to superficial inspection of non-metallic pipes for the hydrocarbons transport

    NASA Astrophysics Data System (ADS)

    Arciniegas, Javier R.; González, Andrés. L.; Quintero, L. A.; Contreras, Carlos R.; Meneses, Jaime E.

    2014-05-01

    Three-dimensional shape measurement is a subject that consistently produces high scientific interest and provides information for medical, industrial and investigative applications, among others. In this paper, it is proposed to implement a three-dimensional (3D) reconstruction system for applications in superficial inspection of non-metallic pipes for the hydrocarbons transport. The system is formed by a CCD camera, a video-projector and a laptop and it is based on fringe projection technique. System functionality is evidenced by evaluating the quality of three-dimensional reconstructions obtained, which allow observing the failures and defects on the study object surface.

  15. LACBED characterization of dislocations in Cu-Al-Ni shape memory alloys processed by powder metallurgy

    NASA Astrophysics Data System (ADS)

    Rodriguez, P. P.; Ibarra, A.; San Jean, J.; Morniro, J. P.; No, M. L.

    2003-10-01

    Powder metallurgy Cu-AI-Ni shape memory alloys show excellent thermomechanical properties, being the fracture behavior close to the one observed in single crystals. However, the microstructural mechanisms responsible of such behavior are still under study. In this paper we present the characterization of the dislocations present in these alloys by Large Angle Convergent Beam Electron Diffraction (LACBED) in two different stages of the elaboration process: after HIP compaction and after hot rolling.

  16. Heat conduction in metal-filled polymers - The role of particle size, shape, and orientation

    NASA Technical Reports Server (NTRS)

    Hansen, D.; Tomkiewicz, R.

    1975-01-01

    This paper presents a new type of analysis for predicting the thermal conductivity of disperse composites from the properties of the component phases and elementary characterizations of particle shapes and orientation. This analysis successfully predicted the sensitivity to particle shape which was confirmed by experiments also reported in this paper. These results suggest that highly elongated particles may be used to achieve dramatic modifications of thermal conductivity and the analysis presented here may be a useful tool in the design or development of disperse composites of specific thermal conductivity. The analysis may also apply to other properties such as electrical conductivity or magnetic permeability.

  17. Synthesis and deposition of metal nanoparticles by gas condensation process

    SciTech Connect

    Maicu, Marina Glöß, Daniel; Frach, Peter; Schmittgens, Ralph; Gerlach, Gerald; Hecker, Dominic

    2014-03-15

    In this work, the synthesis of Pt and Ag nanoparticles by means of the inert gas phase condensation of sputtered atomic vapor is presented. The process parameters (power, sputtering time, and gas flow) were varied in order to study the relationship between deposition conditions and properties of the nanoparticles such as their quantity, size, and size distribution. Moreover, the gas phase condensation process can be combined with a plasma enhanced chemical vapor deposition procedure in order to deposit nanocomposite coatings consisting of metallic nanoparticles embedded in a thin film matrix material. Selected examples of application of the generated nanoparticles and nanocomposites are discussed.

  18. Laser-induced metallic nanograined thin films processing

    SciTech Connect

    Tosa, Nicoleta E-mail: florin.toadere@itim-cj.ro; Toadere, Florin E-mail: florin.toadere@itim-cj.ro; Hojbota, Calin E-mail: florin.toadere@itim-cj.ro; Tosa, Valer E-mail: florin.toadere@itim-cj.ro

    2013-11-13

    A direct laser writing method for designing metallic nanograined thin films is presented. This method takes advantage of photon conversion within a chemical process localized at the focal point. A computer controlled positioning system allows the control of experimental parameters and spatial resolution of the pattern. Spectroscopic investigations reveal variable attenuation of the optical properties in UV-visible range and a spectral imaging processing algorithm simulated the functionality of these films in visible light. This could be an important step for obtaining neutral density attenuators.

  19. Carbon formation and metal dusting in advanced coal gasification processes

    SciTech Connect

    DeVan, J.H.; Tortorelli, P.F.; Judkins, R.R.; Wright, I.G.

    1997-02-01

    The product gases generated by coal gasification systems contain high concentrations of CO and, characteristically, have relatively high carbon activities. Accordingly, carbon deposition and metal dusting can potentially degrade the operation of such gasifier systems. Therefore, the product gas compositions of eight representative gasifier systems were examined with respect to the carbon activity of the gases at temperatures ranging from 480 to 1,090 C. Phase stability calculations indicated that Fe{sub 3}C is stable only under very limited thermodynamic conditions and with certain kinetic assumptions and that FeO and Fe{sub 0.877}S tend to form instead of the carbide. As formation of Fe{sub 3}C is a necessary step in the metal dusting of steels, there are numerous gasifier environments where this type of carbon-related degradation will not occur, particularly under conditions associated with higher oxygen and sulfur activities. These calculations also indicated that the removal of H{sub 2}S by a hot-gas cleanup system may have less effect on the formation of Fe{sub 3}C in air-blown gasifier environments, where the iron oxide phase can exist and is unaffected by the removal of sulfur, than in oxygen-blown systems, where iron sulfide provides the only potential barrier to Fe{sub 3}C formation. Use of carbon- and/or low-alloy steels dictates that the process gas composition be such that Fe{sub 3}C cannot form if the potential for metal dusting is to be eliminated. Alternatively, process modifications could include the reintroduction of hydrogen sulfide, cooling the gas to perhaps as low as 400 C and/or steam injection. If higher-alloy steels are used, a hydrogen sulfide-free gas may be processed without concern about carbon deposition and metal dusting.

  20. TiO{sub 2} nanotube, nanowire, and rhomboid-shaped particle thin films fixed on a titanium metal plate

    SciTech Connect

    Inoue, Yuko; Noda, Iwao; Torikai, Toshio; Watari, Takanori; Hotokebuchi, Takao; Yada, Mitsunori

    2010-01-15

    Titanium dioxide thin films having various nanostructures could be formed by various treatments on sodium titanate nanotube thin films approximately 5 {mu}m thick fixed on titanium metal plates. Using an aqueous solution with a lower hydrochloric acid concentration (0.01 mol/L) and a higher reaction temperature (90 deg. C) than those previously employed, we obtained a hydrogen titanate nanotube thin film fixed onto a titanium metal plate by H{sup +} ion-exchange treatment of the sodium titanate nanotube thin film. Calcination of hydrogen titanate nanotube thin films yielded porous thin films consisting of anatase nanotubes, anatase nanowires, and anatase nanoparticles grown directly from the titanium metal plate. H{sup +} ion-exchange treatment of sodium titanate nanotube thin films at 140 deg. C resulted in porous thin films consisting of rhomboid-shaped anatase nanoparticles. - Graphical abstract: Titanium dioxide nanotube, nanowire, and rhombic particle thin films could be formed by various treatments on a sodium titanate nanotube thin film fixed on a titanium metal plate.

  1. A role for membrane shape and information processing in cardiac physiology.

    PubMed

    Knöll, Ralph

    2015-01-01

    While the heart is a dynamic organ and one of its major functions is to provide the organism with sufficient blood supply, the regulatory feedback systems, which allow adaptation to hemodynamic changes, remain not well understood. Our current description of mechanosensation focuses on stretch-sensitive ion channels, cytoskeletal components, structures such as the sarcomeric Z-disc, costameres, caveolae, or the concept of tensegrity, but these models appear incomplete as the remarkable plasticity of the myocardium in response to biomechanical stress and heart rate variations remains unexplained. Signaling activity at membranes depends on their geometric parameters such as surface area and curvature, which links shape to information processing. In the heart, continuous cycles of contraction and relaxation reshape membrane morphology and hence affect cardio-mechanic signaling. This article provides a brief review on current models of mechanosensation and focuses on how signaling, cardiac myocyte dynamics, and membrane shape interact and potentially give rise to a self-organized system that uses shape to sense the extra- and intracellular environment. This novel concept may help to explain how changes in frequency, and thus membrane shape, affect cardiac plasticity. One of the conclusions is that hypertrophy and associated fibrosis, which have been considered as necessary to cope with increased wall stress, can also be seen as part of complex feedback systems which use local membrane inhomogeneity in different cardiac cell types to influence whole organphysiology and which are predicted to fine-tune and thus regulate membrane-mediated signaling. PMID:25129123

  2. 3D numerical simulation of the evolutionary process of aeolian downsized crescent-shaped dunes

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaosi; Zhang, Yang; Wang, Yuan; Li, Min

    2016-06-01

    A dune constitutive model was coupled with a large eddy simulation (LES) with the Smagorinsky subgrid-scale (SGS) model to accurately describe the evolutionary process of dunes from the macroscopic perspective of morphological dynamics. A 3D numerical simulation of the evolution of aeolian downsized crescent-shaped dunes was then performed. The evolution of the 3D structure of Gaussian-shaped dunes was simulated under the influence of gravity modulation, which was the same with the vertical oscillation of the sand bed to adjust the threshold of sand grain liftoff in wind tunnel experiments under the same wind speed. The influence of gravity modulation intensity on the characteristic scale parameter of the dune was discussed. Results indicated that the crescent shape of the dune was reproduced with the action of gravity during regulation of the saturation of wind-sand flow at specific times. The crescent shape was not dynamically maintained as time passed, and the dunes dwindled until they reached final decomposition because of wind erosion. The height of the dunes decreased over time, and the height-time curve converged as the intensity of modulation increased linearly. The results qualitatively agreed with those obtained from wind tunnel experiments.

  3. Numerical Modeling of Inclusion Behavior in Liquid Metal Processing

    NASA Astrophysics Data System (ADS)

    Bellot, Jean-Pierre; Descotes, Vincent; Jardy, Alain

    2013-09-01

    Thermomechanical performance of metallic alloys is directly related to the metal cleanliness that has always been a challenge for metallurgists. During liquid metal processing, particles can grow or decrease in size either by mass transfer with the liquid phase or by agglomeration/fragmentation mechanisms. As a function of numerical density of inclusions and of the hydrodynamics of the reactor, different numerical modeling approaches are proposed; in the case of an isolated particle, the Lagrangian technique coupled with a dissolution model is applied, whereas in the opposite case of large inclusion phase concentration, the population balance equation must be solved. Three examples of numerical modeling studies achieved at Institut Jean Lamour are discussed. They illustrate the application of the Lagrangian technique (for isolated exogenous inclusion in titanium bath) and the Eulerian technique without or with the aggregation process: for precipitation and growing of inclusions at the solidification front of a Maraging steel, and for endogenous inclusions in the molten steel bath of a gas-stirred ladle, respectively.

  4. Processing dependence of mechanical properties of metallic glass nanowires

    SciTech Connect

    Zhang, Qi; Li, Mo; Li, Qi-Kai

    2015-02-16

    Compared to their crystalline counterparts, nanowires made of metallic glass have not only superb properties but also remarkable processing ability. They can be processed easily and cheaply like plastics via a wide range of methods. To date, the underlying mechanisms of how these different processing routes affect the wires' properties as well as the atomic structure remains largely unknown. Here, by using atomistic modeling, we show that different processing methods can greatly influence the mechanical properties. The nanowires made via focused ion beam milling and embossing exhibit higher strength but localized plastic deformation, whereas that made by casting from liquid shows excellent ductility with homogeneous deformation but reduced strength. The different responses are reflected sensitively in the underlying atomic structure and packing density, some of which have been observed experimentally. The presence of the gradient of alloy concentration and surface effect will be discussed.

  5. NGNP Process Heat Utilization: Liquid Metal Phase Change Heat Exchanger

    SciTech Connect

    Piyush Sabharwall; Mike Patterson; Vivek Utgikar; Fred Gunnerson

    2008-09-01

    One key long-standing issue that must be overcome to fully realize the successful growth of nuclear power is to determine other benefits of nuclear energy apart from meeting the electricity demands. The Next Generation Nuclear Plant (NGNP) will most likely be producing electricity and heat for the production of hydrogen and/or oil retrieval from oil sands and oil shale to help in our national pursuit of energy independence. For nuclear process heat to be utilized, intermediate heat exchange is required to transfer heat from the NGNP to the hydrogen plant or oil recovery field in the most efficient way possible. Development of nuclear reactor - process heat technology has intensified the interest in liquid metals as heat transfer media because of their ideal transport properties. Liquid metal heat exchangers are not new in practical applications. An important rational for considering liquid metals is the potential convective heat transfer is among the highest known. Thus explains the interest in liquid metals as coolant for intermediate heat exchange from NGNP. For process heat it is desired that, intermediate heat exchangers (IHX) transfer heat from the NGNP in the most efficient way possible. The production of electric power at higher efficiency via the Brayton Cycle, and hydrogen production, requires both heat at higher temperatures and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. Compact heat exchangers maximize the heat transfer surface area per volume of heat exchanger; this has the benefit of reducing heat exchanger size and heat losses. High temperature IHX design requirements are governed in part by the allowable temperature drop between the outlet and inlet of the NGNP. In order to improve the characteristics of heat transfer, liquid metal phase change heat exchangers may be more effective and efficient. This paper explores the overall heat transfer characteristics and pressure drop of the phase change

  6. Process for electrolytic deposition of metals on zirconium materials

    DOEpatents

    Donaghy, Robert E.

    1979-01-30

    A process for the electrolytic deposition of a metal layer on an article comprised of zirconium or a zirconium alloy is disclosed. The article is activated in an aged aqueous solution comprising from about 10 to about 20 grams per liter ammonium bifluoride and from about 0.75 to about 2 grams per liter of sulfuric acid. The solution is aged by immersion of pickled zirconium in the solution for at least about 10 minutes. The loosely adhering film formed on the article in the activating step is removed and the article is contacted with an electrolytic plating solution containing the metal to be deposited on the article in the presence of an electrode receiving current.

  7. Process for electroless deposition of metals on zirconium materials

    DOEpatents

    Donaghy, Robert E.

    1978-01-01

    A process for the electroless deposition of a metal layer on an article comprised of zirconium or a zirconium alloy is disclosed. The article is activated in an aged aqueous solution comprising from about 10 to about 20 grams per liter ammonium bifluoride and from about 0.75 to about 2 grams per liter of sulfuric acid. The solution is aged by immersion of pickled zirconium in the solution for at least about 10 minutes. The loosely adhering film formed on the article in the activating step is removed and the article is contacted with an electroless plating solution containing the metal to be deposited on the article upon sufficient contact with the article.

  8. Metal chelate process to remove pollutants from fluids

    DOEpatents

    Chang, Shih-Ger T.

    1994-01-01

    The present invention relates to improved methods using an organic iron chelate to remove pollutants from fluids, such as flue gas. Specifically, the present invention relates to a process to remove NO.sub.x and optionally SO.sub.2 from a fluid using a metal ion (Fe.sup.2+) chelate wherein the ligand is a dimercapto compound wherein the --SH groups are attached to adjacent carbon atoms (HS--C--C--SH) or (SH--C--CCSH) and contain a polar functional group so that the ligand of DMC chelate is water soluble. Alternatively, the DMC' is covalently attached to a water insoluble substrate such as a polymer or resin, e.g., polystyrene. The chelate is regenerated using electroreduction or a chemical additive. The dimercapto compound bonded to a water insoluble substrate is also useful to lower the concentration or remove hazardous metal ions from an aqueous solution.

  9. Metal Alloy Compositions And Process Background Of The Invention

    DOEpatents

    Flemings, Merton C.; Martinez-Ayers, Raul A.; de Figueredo, Anacleto M.; Yurko, James A.

    2003-11-11

    A skinless metal alloy composition free of entrapped gas and comprising primary solid discrete degenerate dendrites homogeneously dispersed within a secondary phase is formed by a process wherein the metal alloy is heated in a vessel to render it a liquid. The liquid is then rapidly cooled while vigorously agitating it under conditions to avoid entrapment of gas while forming solid nuclei homogeneously distributed in the liquid. Agitation then is ceased when the liquid contains a small fraction solid or the liquid-solid alloy is removed from the source of agitation while cooling is continued to form the primary solid discrete degenerate dendrites in liquid secondary phase. The solid-liquid mixture then can be formed such as by casting.

  10. Metal chelate process to remove pollutants from fluids

    DOEpatents

    Chang, S.G.T.

    1994-12-06

    The present invention relates to improved methods using an organic iron chelate to remove pollutants from fluids, such as flue gas. Specifically, the present invention relates to a process to remove NO[sub x] and optionally SO[sub 2] from a fluid using a metal ion (Fe[sup 2+]) chelate wherein the ligand is a dimercapto compound wherein the --SH groups are attached to adjacent carbon atoms (HS--C--C--SH) or (SH--C--CCSH) and contain a polar functional group so that the ligand of DMC chelate is water soluble. Alternatively, the DMC is covalently attached to a water insoluble substrate such as a polymer or resin, e.g., polystyrene. The chelate is regenerated using electroreduction or a chemical additive. The dimercapto compound bonded to a water insoluble substrate is also useful to lower the concentration or remove hazardous metal ions from an aqueous solution. 26 figures.

  11. Thermochemical Processing of Radioactive Waste Using Powder Metal Fuels

    SciTech Connect

    Ojovan, M. I.; Sobolev, I. A.; Dmitriev, S. A.; Panteleev, V. I.; Karlina, O. K.; Klimov. V. L.

    2003-02-25

    Problematic radioactive wastes were generated during various activities of both industrial facilities and research institutions usually in relative small amounts. These can be spent ion exchange resins, inorganic absorbents, wastes from research nuclear reactors, irradiated graphite, mixed, organic or chlorine-containing radioactive waste, contaminated soils, un-burnable heavily surface-contaminated materials, etc. Conventional treatment methods encounter serious problems concerning processing efficiency of such waste, e.g. complete destruction of organic molecules and avoiding of possible emissions of radionuclides, heavy metals and chemically hazardous species. Some contaminations cannot be removed from surface using common decontamination methods. Conditioning of ash residues obtained after treatment of solid radioactive waste including ashes received from treating problematic wastes also is a complicated task. Moreover due to relative small volume of specific type radioactive waste the development of target treatment procedures and facilities to conduct technological processes and their deployment could be economically unexpedient and ecologically no justified. Thermochemical processing technologies are used for treating and conditioning problematic radioactive wastes. The thermochemical processing uses powdered metal fuels (PMF) that are specifically formulated for the waste composition and react chemically with the waste components. The composition of the PMF is designed in such a way as to minimize the release of hazardous components and radionuclides in the off gas and to confine the contaminants in the ash residue. The thermochemical procedures allow decomposition of organic matter and capturing hazardous radionuclides and chemical species simultaneously. A significant advantage of thermochemical processing is its autonomy. Thermochemical treatment technologies use the energy of exothermic reactions in the mixture of radioactive or hazardous waste with PMF

  12. Nanoparticle shape evolution and proximity effects during tip-induced electrochemical processes

    DOE PAGES

    Yang, Sangmo; Paranthaman, Mariappan Parans; Noh, Tae Won; Kalinin, Sergei V.; Strelcov, Evgheni

    2016-01-08

    The voltage spectroscopies in scanning probe microscopy (SPM) techniques are widely used to investigate the electrochemical processes in nanoscale volumes, which are important for current key applications, such as batteries, fuel cells, catalysts, and memristors. The spectroscopic measurements are commonly performed on a grid of multiple points to yield spatially resolved maps of reversible and irreversible electrochemical functionalities. Hence, the spacing between measurement points is an important parameter to be considered, especially for irreversible electrochemical processes. Here, we report nonlocal electrochemical dynamics in chains of Ag particles fabricated by the SPM tip on a silver ion solid electrolyte. When themore » grid spacing is small compared with the size of the formed Ag particles, anomalous chains of unequally sized particles with double periodicity evolve. This behavior is ascribed to a proximity effect during the tip-induced electrochemical process, specifically, size-dependent silver particle growth following the contact between the particles. In addition, fractal shape evolution of the formed Ag structures indicates that the growth-limiting process changes from Ag+/Ag redox reaction to Ag+-ion diffusion with the increase in the applied voltage and pulse duration. Our study shows that characteristic shapes of the electrochemical products are good indicators for determining the underlying growth-limiting process, and emergence of complex phenomena during spectroscopic mapping of electrochemical functionalities.« less

  13. Shape Memory Effect in Cast Versus Deformation-Processed NiTiNb Alloys

    NASA Astrophysics Data System (ADS)

    Hamilton, Reginald F.; Lanba, Asheesh; Ozbulut, Osman E.; Tittmann, Bernhard R.

    2015-06-01

    The shape memory effect (SME) response of a deformation-processed NiTiNb shape memory alloy is benchmarked against the response of a cast alloy. The insoluble Nb element ternary addition is known to widen the hysteresis with respect to the binary NiTi alloy. Cast microstructures naturally consist of a cellular arrangement of characteristic eutectic microconstituents surrounding primary matrix regions. Deformation processing typically aligns the microconstituents such that the microstructure resembles discontinuous fiber-reinforced composites. Processed alloys are typically characterized for heat-to-recover applications and thus deformed at constant temperature and subsequently heated for SME recovery, and the critical stress levels are expected to facilitate plastic deformation of the microconstituents. The current work employs thermal cycling under constant bias stresses below those critical levels. This comparative study of cast versus deformation-processed NiTiNb alloys contrasts the strain-temperature responses in terms of forward Δ T F = M s - M f and reverse Δ T R = A f - A s temperature intervals, the thermal hysteresis, and the recovery ratio. The results underscore that the deformation-processed microstructure inherently promotes irreversibility and differential forward and reverse transformation pathways.

  14. Nanoparticle Shape Evolution and Proximity Effects During Tip-Induced Electrochemical Processes.

    PubMed

    Yang, Sang Mo; Paranthaman, Mariappan Parans; Noh, Tae Won; Kalinin, Sergei V; Strelcov, Evgheni

    2016-01-26

    Voltage spectroscopies in scanning probe microscopy (SPM) techniques are widely used to investigate the electrochemical processes in nanoscale volumes, which are important for current key applications, such as batteries, fuel cells, catalysts, and memristors. The spectroscopic measurements are commonly performed on a grid of multiple points to yield spatially resolved maps of reversible and irreversible electrochemical functionalities. Hence, the spacing between measurement points is an important parameter to be considered, especially for irreversible electrochemical processes. Here, we report nonlocal electrochemical dynamics in chains of Ag particles fabricated by the SPM tip on a silver ion solid electrolyte. When the grid spacing is small compared with the size of the formed Ag particles, anomalous chains of unequally sized particles with double periodicity evolve. This behavior is ascribed to a proximity effect during the tip-induced electrochemical process, specifically, size-dependent silver particle growth following the contact between the particles. In addition, fractal shape evolution of the formed Ag structures indicates that the growth-limiting process changes from Ag(+)/Ag redox reaction to Ag(+)-ion diffusion with the increase in the applied voltage and pulse duration. This study shows that characteristic shapes of the electrochemical products are good indicators for determining the underlying growth-limiting process, and emergence of complex phenomena during spectroscopic mapping of electrochemical functionalities. PMID:26743324

  15. Nanoparticle Shape Evolution and Proximity Effects During Tip-Induced Electrochemical Processes.

    PubMed

    Yang, Sang Mo; Paranthaman, Mariappan Parans; Noh, Tae Won; Kalinin, Sergei V; Strelcov, Evgheni

    2016-01-26

    Voltage spectroscopies in scanning probe microscopy (SPM) techniques are widely used to investigate the electrochemical processes in nanoscale volumes, which are important for current key applications, such as batteries, fuel cells, catalysts, and memristors. The spectroscopic measurements are commonly performed on a grid of multiple points to yield spatially resolved maps of reversible and irreversible electrochemical functionalities. Hence, the spacing between measurement points is an important parameter to be considered, especially for irreversible electrochemical processes. Here, we report nonlocal electrochemical dynamics in chains of Ag particles fabricated by the SPM tip on a silver ion solid electrolyte. When the grid spacing is small compared with the size of the formed Ag particles, anomalous chains of unequally sized particles with double periodicity evolve. This behavior is ascribed to a proximity effect during the tip-induced electrochemical process, specifically, size-dependent silver particle growth following the contact between the particles. In addition, fractal shape evolution of the formed Ag structures indicates that the growth-limiting process changes from Ag(+)/Ag redox reaction to Ag(+)-ion diffusion with the increase in the applied voltage and pulse duration. This study shows that characteristic shapes of the electrochemical products are good indicators for determining the underlying growth-limiting process, and emergence of complex phenomena during spectroscopic mapping of electrochemical functionalities.

  16. Beyond U-Shaped Development in Infants' Processing of Faces: An Information-Processing Account

    ERIC Educational Resources Information Center

    Cashon, Cara H.; Cohen, Leslie B.

    2004-01-01

    The development of the "inversion" effect in face processing was examined in infants 3 to 6 months of age by testing their integration of the internal and external features of upright and inverted faces using a variation of the "switch" visual habituation paradigm. When combined with previous findings showing that 7-month-olds use integrative…

  17. Feature binding and the processing of global-local shapes in bilingual and monolingual children.

    PubMed

    Cottini, Milvia; Pieroni, Laura; Spataro, Pietro; Devescovi, Antonella; Longobardi, Emiddia; Rossi-Arnaud, Clelia

    2015-04-01

    In the present study, we examined the effects of bilingualism and age on a color-shape binding task (assessing visual working memory) and a global-local task (assessing inhibitory processes) in a sample of 55 bilingual and 49 monolingual children 8 and 10 years old. In the color-shape binding task, corrected recognition scores increased in older children; bilingual children performed better than monolinguals in the shape-only condition, but the two groups were equally accurate in the color-only and combination conditions. In the global-local task, accuracy was higher in bilingual than in monolingual children, particularly on incongruent trials; monolingual children showed a strong global precedence effect (higher accuracy in the global than in the local conditions and greater global-to-local interference), whereas bilingual children exhibited a small, but significant, local precedence effect (higher accuracy in the local than in the global conditions and greater local-to-global interference). These findings confirm and extend previous evidence indicating that the bilingualism advantage is more pronounced in working memory tasks involving inhibitory processes.

  18. Shape, metal abundance, chemistry, and origin of chondrules in the Renazzo (CR) chondrite

    SciTech Connect

    Ebel, D.S.; Weisberg, M.K.; Hertz, J.; Campbell, A.J.

    2009-03-31

    We used synchrotron X-ray microtomography to image in 3-dimensions (3D) eight whole chondrules in a {approx}1 cm{sup 3} piece of the Renazzo (CR) chondrite at {approx}17 {micro}m per volume element (voxel) edge. We report the first volumetric (3D) measurement of metal/silicate ratios in chondrules and quantify indices of chondrule sphericity. Volumetric metal abundances in whole chondrules range from 1 to 37 volume % in 8 measured chondrules and by inspection in tomography data. We show that metal abundances and metal grain locations in individual chondrules cannot be reliably obtained from single random 2D sections. Samples were physically cut to intersect representative chondrules multiple times and to verify 3D data. Detailed 2D chemical analysis combined with 3D data yield highly variable whole-chondrule Mg/Si ratios with a supra-chondritic mean value, yet the chemically diverse, independently formed chondrules are mutually complementary in preserving chondritic (solar) Fe/Si ratios in the aggregate CR chondrite. These results are consistent with localized chondrule formation and rapid accretion resulting in chondrule + matrix aggregates (meteorite parent bodies) that preserve the bulk chondritic composition of source regions.

  19. Hybrid process for heavy metal removal from wastewater sludge.

    PubMed

    Drogui, Patrick; Blais, Jean-François; Mercier, Guy

    2005-01-01

    Bioleaching processes have been demonstrated to be effective technologies in removing heavy metals from wastewater sludge, but long hydraulic retention times are typically required to operate these bioprocesses. A hybrid process (coupling biological and chemical processes) has been explored in laboratory pilot-scale experiments for heavy metals (cadmium [Cd], copper [Cu], chromium [Cr], and zinc [Zn]) removal from three types of sludge (primary sludge, secondary activated sludge, and a mixture of primary and secondary sludge). The hybrid process consisted of producing a concentrate ferric ion solution followed by chemical treatment of sludges. Ferric iron solution was produced biologically via oxidation of ferrous iron by A. ferrooxidans in a continuous-flow stirred tank (5.2 L) reactor (CSTR). Wastewater sludge filtrate (WSF) containing nutrients (phosphorus and nitrogen) has been used as culture media to support the growth and activity of indigenous iron-oxidizing bacteria. Results showed that total organic carbon (TOC) concentrations of the culture media in excess of 235 mg/L were found to be inhibitory to bacterial growth. The oxidation rate increased as ferrous iron concentrations ranged from 10 to 40 g Fe2+/L. The percentage of ferrous iron (Fe2+) oxidized to ferric iron (Fe3+) increased as the hydraulic retention time (HRT) increased from 12 to 48 h. Successful and complete Fe2+ oxidation was recorded at a HRT of 48 h using 10 g Fe2+/L. Subsequently, ferric ion solution produced by A. ferrooxidans in sludge filtrate was used to solubilize heavy metals contained in wastewater sludge. The best solubilization was obtained with a mixture of primary and secondary sludge, demonstrating a removal efficiency of 63, 71, 49, and 80% for Cd, Cu, Cr, and Zn, respectively. PMID:16121505

  20. Development and characterization of polymers-metallic hot embossing process for manufacturing metallic micro-parts

    NASA Astrophysics Data System (ADS)

    Sahli, M.; Millot, C.; Gelin, J.-C.; Barrière, T.

    2011-01-01

    In the recent years, hot embossing process becomes a promising process for the replication of polymer micro-structures associated to its manufacturing capability related to a relatively low component cost. This rising demand has prompted the development of various micro-manufacturing techniques in an attempt to get micro-parts in large batch. The paper investigates the way to get metallic micro-parts through the hot embossing process. The micro-manufacturing process consists in three stages. In the first one, the different metallic feedstocks with 50 to 60% powder loading in volume have been prepared with adapted polymers/powders formulations. In a second stage, an elastomeric master has been used to obtain micro-parts on a plastic loaded substrate with developed mixture based on polypropylene, paraffin wax and stearic acid. Finally, a thermal debinding stage in nitrogen atmosphere followed by a solid state pre-sintering stage has been applied, in order to eliminate the pores between powder particles in the debinded components. Then the porous components are agglomerated by solid state diffusion after heating to a temperature slightly lower than the melting temperature related to the material used in the process, to form an homogenous structure when full densification is achieved. The advantages of this approach include: rapid manufacturing of injection tools with high-quality, easy demoulding of metallic parts from the elastomeric moulds and great flexibility related to the choices of material. The paper describes all the processing stages and the way to characterize the geometrical, physical and mechanical properties of the resulting micro-parts.

  1. Method for preparing metal powder, device for preparing metal powder, method for processing spent nuclear fuel

    DOEpatents

    Park, Jong-Hee

    2011-11-29

    A method for producing metal powder is provided the comprising supplying a molten bath containing a reducing agent, contacting a metal oxide with the molten bath for a time and at a temperature sufficient to reduce the metal in the metal oxide to elemental metal and produce free oxygen; and isolating the elemental metal from the molten bath.

  2. Emerging technologies in extraction and processing of metals

    NASA Astrophysics Data System (ADS)

    Reddy, Ramana G.

    2003-04-01

    The growing need to conserve energy and materials and prevent environmental pollution led to an increased demand for better understanding of potential as well as existing processes. In this context, thermodynamic and transport modeling of materials and processes provides a rapid and cost-effective means of conducting and minimizing the complexity of experimental investigations and developing innovative and environmentally friendly metallurgical processes. This presentation concentrates on some fundamentals on new technologies as extractive metallurgy of copper, lead, aluminum, and other nonferrous metals and processing of nanocomposites. The newer routes of copper smelting and modeling of impurities in copper and lead slags and mattes are reviewed. The copper smelting capacity increased by a factor of 10 during the last three decades, the smelting rate increased by a factor of 6, and the process fuel equivalent decreased by a factor of 2. The a priori prediction, with no adjustable parameters, of impurity capacities of S and As in copper slags and S in lead slags, based on the Reddy-Blander model, is reviewed. Excellent agreement between the model-predicted capacities data and laboratory experimental and industrial data was observed. The model is an invaluable tool for optimization of process parameters in the efficient removal of impurities from the nonferrous-metals smelting and refining processes. A new in-situ processing technology for the production of a lightweight alloy matrix with ceramic particle reinforcements such as SiC in aluminum alloy matrix composites by bubbling reactive gas is reviewed. Thermal plasma processing of a nanoscale aluminum alloy matrix with TiC and TiN composites is discussed. The in-situ formed reinforcements are thermodynamically stable, and the composite particles are of uniform size. The optimum process parameters for the production of composite powders by thermal plasma are discussed. A low-temperature aluminum production and

  3. A binary image reconstruction technique for accurate determination of the shape and location of metal objects in x-ray computed tomography.

    PubMed

    Wang, Jing; Xing, Lei

    2010-01-01

    The presence of metals in patients causes streaking artifacts in X-ray CT and has been recognized as a problem that limits various applications of CT imaging. Accurate localization of metals in CT images is a critical step for metal artifacts reduction in CT imaging and many practical applications of CT images. The purpose of this work is to develop a method of auto-determination of the shape and location of metallic object(s) in the image space. The proposed method is based on the fact that when a metal object is present in a patient, a CT image can be divided into two prominent components: high density metal and low density normal tissues. This prior knowledge is incorporated into an objective function as the regularization term whose role is to encourage the solution to take a form of two intensity levels. A computer simulation study and four experimental studies are performed to evaluate the proposed approach. Both simulation and experimental studies show that the presented algorithm works well even in the presence of complicated shaped metal objects. For a hexagonally shaped metal embedded in a water phantom, for example, it is found that the accuracy of metal reconstruction is within sub-millimeter.

  4. Validation of Two Hydrocodes with a Bi-Metallic Shaped Charge Experiment

    SciTech Connect

    Ingraham, Daniel J.

    2012-08-16

    Staggered grid (SGH) and cell-centered (CCH) Lagrangian Hydro are two approaches to modeling high explosives (HE) experiments. HE experiments involve complex flows. For example, the discontinuity in the tangential velocity across a frictionless contact surface. In this work, the SGH and CCH schemes with a contact surface algorithm are used to simulate a bimetallic shaped charge experiment using FLAG. Experiment will be performed at LANL in the coming year and used to validate the SGH and CCH schemes results.

  5. C-shaped specimen plane strain fracture toughness tests. [metallic materials

    NASA Technical Reports Server (NTRS)

    Buzzard, R. T.; Fisher, D. M.

    1977-01-01

    Test equipment, procedures, and data obtained in the evaluation of C-shaped specimens are presented. Observations reported on include: specimen preparation and dimensional measurement; modifications to the standard ASTM E 399 displacement gage, which permit punch mark gage point engagement; and a measurement device for determining the interior and exterior radii of ring segments. Load displacement ratios were determined experimentally which agreed with analytically determined coefficients for three different gage lengths on the inner surfaces of radially-cracked ring segments.

  6. Numerical simulation study on active and passive hydroforming process optimization of box shaped part

    NASA Astrophysics Data System (ADS)

    Zeng, Y. P.; Dong, J. L.; He, T. D.; Wang, B.

    2016-08-01

    Low qualified rate and inferior quality frequently occurring in the general deep drawing process of a certain box-shaped part, now use hydroforming to optimize forming process, in order to study the effect of hydroforming for improving the quality and formability, purposed five process schemes: general deep drawing, active hydroforming, passive hydroforming, general deep drawing combined with active hydroforming, passive combined with active hydroforming. Each process was simulated by finite element simulation and results were analysed. The results indicate the passive combined with active hydroforming is the best scheme which can obtain smallest thickness thinning and satisfactory formability, then optimized hydroforming pressure, blank holder force subsequently by adjust the simulation parameters. Research result proves that active/passive hydroforming is a new method for complex parts forming.

  7. Concept Feasibility Report for Using Co-Extrusion to Bond Metals to Complex Shapes of U-10Mo

    SciTech Connect

    Lavender, Curt A.; Paxton, Dean M.; Smith, Mark T.; Soulami, Ayoub; Joshi, Vineet V.; Burkes, Douglas

    2013-12-30

    In support of the Convert Program of the U.S. Department of Energy’s National Nuclear Security Administration (DOE/NNSA) Global Threat Reduction Initiative (GTRI), Pacific Northwest National Laboratory (PNNL) has been investigating manufacturing processes for the uranium-10% molybdenum (U-10Mo) alloy plate fuel for the U.S. high-performance research reactors (USHPRR). This report documents the results of PNNL’s efforts to develop the extrusion process for this concept. The approach to the development of a co-extruded complex-shaped fuel has been described and an extrusion of DU-10Mo was made. The initial findings suggest that given the extrusion forces required for processing U-10Mo, the co-extrusion process can meet the production demands of the USHPRR fuel and may be a viable production method. The development activity is in the early stages and has just begun to identify technical challenges to address details such as dimensional tolerances and shape control. New extrusion dies and roll groove profiles have been developed and will be assessed by extrusion and rolling of U-10Mo during the next fiscal year. Progress on the development and demonstration of the co-extrusion process for flat and shaped fuel is reported in this document

  8. Universality and time-scale invariance for the shape of planar Lévy processes.

    PubMed

    Randon-Furling, Julien

    2014-05-01

    For a broad class of planar Markov processes, viz. Lévy processes satisfying certain conditions (valid, e.g., in the case of Brownian motion and Lévy flights), we establish an exact, universal formula describing the shape of the convex hull of sample paths. We show indeed that the average number of edges joining paths' points separated by a time lapse Δτ ∈ [Δτ(1),Δτ(2)] is equal to 2 ln(Δτ(2)/Δτ(1)), regardless of the specific distribution of the process's increments and regardless of its total duration T. The formula also exhibits invariance when the time scale is multiplied by any constant. Apart from its theoretical importance, our result provides insights regarding the shape of two-dimensional objects (e.g., polymer chains) modeled by the sample paths of stochastic processes generally more complex than Brownian motion. In particular, for a total time (or parameter) duration T, the average number of edges on the convex hull ("cut off" to discard edges joining points separated by a time lapse shorter than some Δτ < T) will be given by 2 ln(T/Δτ). Thus it will only grow logarithmically, rather than at some higher pace.

  9. Supergene processes on ore deposits - a source of heavy metals

    SciTech Connect

    Martycak, K.; Zeman, J.; Vacek-Vesely, M.

    1994-03-01

    The study of supergene processes (i.e., secondary processes running in ore deposits and driven by thermodynamic nonequilibrium between ore- and rock-forming minerals and natural waters, gasses, etc.) is important in order to understand the migration of heavy metals from ore into their adjacent surroundings. The contamination of the local environment can be characterized by the composition of pore waters. The Pb-Zn-Cu ore deposits of Zlate Hory (Czech Republic) have been chosen for a detailed study of pore solutions. A simple model has been created to describe the evolution of supergene processes in the ore deposits. This model is based on the determination of chemical composition of pore solutions. The dilution of pore solutions of such mineral deposits results in acid mine drainage. Pore solutions can have, during specific stages of their evolution, relatively high concentrations of Cu (0.09 mol/kg), Zn (0.1 mol/kg), SO{sub 4} (0.8 mol/kg) and an extremely low pH (1.38). The supergene alteration of pyrite is the most important process determining the character of pore water. This reaction causes significant acidification and is a leading source of acid mine drainage. The leached zone originates from the interaction of pyrite and limonite. Increased concentrations of heavy metals and sulfates occur in pore waters. The dynamic composition of pore waters within ore deposits undergoing the supergene process can be used to distinguish: (1) three main zones - limonite, transition, and primary zone and (2) two areas - an area with the highest intensity of weathering processes and an area of weathering initiation. In these areas the rate of sulfide oxidation is higher as a result of low pH. From the study of these zones and areas we can further our knowledge of ore body, pore solution, acid mine drainage, and contamination of the local environment. 32 refs., 12 figs., 3 tabs.

  10. Processing of Refractory Metal Alloys for JOYO Irradiations

    SciTech Connect

    RF Luther; ME Petrichek

    2006-02-21

    This is a summary of the refractory metal processing experienced by candidate Prometheus materiats as they were fabricated into specimens destined for testing within the JOYO test reactor, ex-reactor testing at Oak Ridge National Laboratory (ORNL), or testing within the NRPCT. The processing is described for each alloy from the point of inception to the point where processing was terminated due to the cancellation of Naval Reactor's involvement in the Prometheus Project. The alloys included three tantalum-base alloys (T-111, Ta-10W, and ASTAR-811C), a niobium-base alloy, (FS-85), and two molybdenum-rhenium alloys, one containing 44.5 w/o rhenium, and the other 47.5 w/o rhenium. Each of these alloys was either a primary candidate or back-up candidate for cladding and structural applications within the space reactor. Their production was intended to serve as a forerunner for large scale production ingots that were to be procured from commercial refractory metal vendors such as Wah Chang.

  11. Superior metallic alloys through rapid solidification processing (RSP) by design

    SciTech Connect

    Flinn, J.E.

    1995-05-01

    Rapid solidification processing using powder atomization methods and the control of minor elements such as oxygen, nitrogen, and carbon can provide metallic alloys with superior properties and performance compared to conventionally processing alloys. Previous studies on nickel- and iron-base superalloys have provided the baseline information to properly couple RSP with alloy composition, and, therefore, enable alloys to be designed for performance improvements. The RSP approach produces powders, which need to be consolidated into suitable monolithic forms. This normally involves canning, consolidation, and decanning of the powders. Canning/decanning is expensive and raises the fabrication cost significantly above that of conventional, ingot metallurgy production methods. The cost differential can be offset by the superior performance of the RSP metallic alloys. However, without the performance database, it is difficult to convince potential users to adopt the RSP approach. Spray casting of the atomized molten droplets into suitable preforms for subsequent fabrication can be cost competitive with conventional processing. If the fine and stable microstructural features observed for the RSP approach are preserved during spray casing, a cost competitive product can be obtained that has superior properties and performance that cannot be obtained by conventional methods.

  12. VOLATILE CHLORIDE PROCESS FOR THE RECOVERY OF METAL VALUES

    DOEpatents

    Hanley, W.R.

    1959-01-01

    A process is presented for recovering uranium, iron, and aluminum from centain shale type ores which contain uranium in minute quantities. The ore is heated wiih a chlorinating agent. such as chlorine, to form a volatilized stream of metal chlorides. The chloride stream is then passed through granular alumina which preferentially absorbs the volatile uranium chloride and from which the uranium may later be recovered. The remaining volatilized chlorides, chiefly those of iron and aluminum, are further treated to recover chlorine gas for recycle, and to recover ferric oxide and aluminum oxide as valuable by-products.

  13. Processing and property evaluation of metal matrix superconducting materials

    NASA Technical Reports Server (NTRS)

    Rao, Appajosula S.

    1995-01-01

    Metal - superconductor (YBCO) systems have been prepared and characterized by resistivity, ac susceptibility and dc SQUID magnetic moment measurements. The silver composites showed superconducting transition for all the composites processed and the superconducting transition temperature tends to depend upon the concentration of the silver in the composite. Aluminum composites showed an unusual resistivity results with two transitions around 90 K and 120 K. The superconducting property of silver composites can be explained qualitatively in terms of the proximity theory that has been suggested for the low temperature superconductors.

  14. Synthesis of metal nanoparticles inside living human cells based on the intracellular formation process.

    PubMed

    El-Said, Waleed A; Cho, Hyeon-Yeol; Yea, Cheol-Heon; Choi, Jeong-Woo

    2014-02-12

    Intracellular and extracellular formation of Au and Ag NPs with different sizes and shapes using human cells has been developed as green method, which does not require the use of any reducing agents. Also, the cell lysis is used for production of different metal NPs. Our results demonstrate that treatment of human cells with various metal ions cause cell fixation.

  15. Network structure dependence on unconstrained isothermal-recovery processes for shape-memory thiol-epoxy "click" systems

    NASA Astrophysics Data System (ADS)

    Belmonte, Alberto; Fernández-Francos, Xavier; De la Flor, Silvia; Serra, Àngels

    2016-07-01

    The shape-memory response (SMR) of "click" thiol-epoxy polymers produced using latent catalysts, with different network structure and thermo-mechanical properties, was tested on unconstrained shape-recovery processes under isothermal conditions. Experiments at several programming temperatures ( T_{prog}) and isothermal-recovery temperatures ( T_{iso}) were carried out, and the shape-memory stability was analyzed through various consecutive shape-memory cycles. The temperature profile during the isothermal-recovery experiments was monitored, and it showed that the shape-recovery process takes place while the sample is becoming thermally stable and before stable isothermal temperature conditions are eventually reached. The shape-recovery process takes place in two different stages regardless of T_{iso}: a slow initial stage until the process is triggered at a temperature strongly related with the beginning of network relaxation, followed by the typical exponential decay of the relaxation processes until completion at a temperature below or very close to Tg. The shape-recovery process is slower in materials with more densely crosslinked and hindered network structures. The shape-recovery time ( t_{sr}) is significantly reduced when the isothermal-recovery temperature T_{iso} increases from below to above Tg because the network relaxation dynamics accelerates. However, the temperature range from the beginning to the end of the recovery process is hardly affected by T_{iso}; at higher T_{iso} it is only slightly shifted to higher temperatures. These results suggest that the shape-recovery process can be controlled by changing the network structure and working at T_{iso} < Tg to maximize the effect of the structure and/or by increasing T_{iso} to minimize the effect but increasing the shape-recovery rate.

  16. Water treatment process and system for metals removal using Saccharomyces cerevisiae

    SciTech Connect

    Krauter, Paula A. W.; Krauter, Gordon W.

    2002-01-01

    A process and a system for removal of metals from ground water or from soil by bioreducing or bioaccumulating the metals using metal tolerant microorganisms Saccharomyces cerevisiae. Saccharomyces cerevisiae is tolerant to the metals, able to bioreduce the metals to the less toxic state and to accumulate them. The process and the system is useful for removal or substantial reduction of levels of chromium, molybdenum, cobalt, zinc, nickel, calcium, strontium, mercury and copper in water.

  17. Cleaning Process Development for Metallic Additively Manufactured Parts

    NASA Technical Reports Server (NTRS)

    Tramel, Terri L.; Welker, Roger; Lowery, Niki; Mitchell, Mark

    2014-01-01

    Additive Manufacturing of metallic components for aerospace applications offers many advantages over traditional manufacturing techniques. As a new technology, many aspects of its widespread utilization remain open to investigation. Among these are the cleaning processes that can be used for post finishing of parts and measurements to verify effectiveness of the cleaning processes. Many cleaning and drying processes and measurement methods that have been used for parts manufactured using conventional techniques are candidates that may be considered for cleaning and verification of additively manufactured parts. Among these are vapor degreasing, ultrasonic immersion and spray cleaning, followed by hot air drying, vacuum baking and solvent displacement drying. Differences in porosity, density, and surface finish of additively manufactured versus conventionally manufactured parts may introduce new considerations in the selection of cleaning and drying processes or the method used to verify their effectiveness. This presentation will review the relative strengths and weaknesses of different candidate cleaning and drying processes as they may apply to additively manufactured metal parts for aerospace applications. An ultrasonic cleaning technique for exploring the cleanability of parts will be presented along with an example using additively manufactured Inconel 718 test specimens to illustrate its use. The data analysis shows that this ultrasonic cleaning approach results in a well-behaved ultrasonic cleaning/extraction behavior. That is, it does not show signs of accelerated cavitation erosion of the base material, which was later confirmed by neutron imaging. In addition, the analysis indicated that complete cleaning would be achieved by ultrasonic immersion cleaning at approximately 5 minutes, which was verified by subsequent cleaning of additional parts.

  18. One-step synthesis of metallic and metal oxide nanoparticles using amino-PEG oligomers as multi-purpose ligands: size and shape control, and quasi-universal solvent dispersibility.

    PubMed

    Rubio-Garcia, Javier; Coppel, Yannick; Lecante, Pierre; Mingotaud, Christophe; Chaudret, Bruno; Gauffre, Fabienne; Kahn, Myrtil L

    2011-01-21

    A one-step and room temperature synthesis toward metallic and metal oxide nanoparticles soluble both in water and organic solvent is reported. This was achieved using amino-PEG oligomers that make it possible to control the size and shape of the nanoparticles.

  19. Liquid crystal materials and structures for image processing and 3D shape acquisition

    NASA Astrophysics Data System (ADS)

    Garbat, K.; Garbat, P.; Jaroszewicz, L.

    2012-03-01

    The image processing supported by liquid crystals device has been used in numerous imaging applications, including polarization imaging, digital holography and programmable imaging. Liquid crystals have been extensively studied and are massively used in display and optical processing technology. We present here the main relevant parameters of liquid crystal for image processing and 3D shape acquisition and we compare the main liquid crystal options which can be used with their respective advantages. We propose here to compare performance of several types of liquid crystal materials: nematic mixtures with high and medium optical and dielectrical anisotropies and relatively low rotational viscosities nematic materials which may operate in TN mode in mono and dual frequency addressing systems.

  20. Laser and Surface Processes of NiTi Shape Memory Elements for Micro-actuation

    NASA Astrophysics Data System (ADS)

    Nespoli, Adelaide; Biffi, Carlo Alberto; Previtali, Barbara; Villa, Elena; Tuissi, Ausonio

    2014-04-01

    In the current microtechnology for actuation field, shape memory alloys (SMA) are considered one of the best candidates for the production of mini/micro devices thanks to their high power-to-weight ratio as function of the actuator weight and hence for their capability of generating high mechanical performance in very limited spaces. In the microscale the most suitable conformation of a SMA actuator is given by a planar wavy formed arrangement, i.e., the snake-like shape, which allows high strokes, considerable forces, and devices with very low sizes. This uncommon and complex geometry becomes more difficult to be realized when the actuator dimensions are scaled down to micrometric values. In this work, micro-snake-like actuators are laser machined using a nanosecond pulsed fiber laser, starting from a 120- μm-thick NiTi sheet. Chemical and electrochemical surface polishes are also investigated for the removal of the thermal damages of the laser process. Calorimetric and thermo-mechanical tests are accomplished to assess the NiTi microdevice performance after each step of the working process. It is shown that laser machining has to be followed by some post-processes in order to obtain a micro-actuator with good thermo-mechanical properties.

  1. Attentional modulation of neural processing of shape, color, and velocity in humans

    SciTech Connect

    Corbetta, M.; Miezin, F.M.; Dobmeyer, S.; Shulman, G.L.; Petersen, S.E. )

    1990-06-22

    Positron emission tomography (PET) was used to measure changes in regional cerebral blood flow of normal subjects, while they were discriminating different attributes (shape, color, and velocity) of the same set of visual stimuli. Psychophysical evidence indicated that the sensitivity for discriminating subtle stimulus changes was higher when subjects focused attention on one attribute than when they divided attention among several attributes. Correspondingly, attention enhanced the activity of different regions of extrastriate visual cortex that appear to be specialized for processing information related to the selected attribute.

  2. Flow, heat transfer, and free surface shape during the optical fiber drawing process

    NASA Astrophysics Data System (ADS)

    Xiao, Zhihui

    1997-12-01

    A two-dimensional finite element model is introduced for analyzing glass and gas flows, heat transfer, and fiber formation during the optical fiber drawing process. This study consists of simulations in three different areas: the upper region, the tip region, and the whole furnace region. Conjugating the glass and gas flows and heat transfer, the shapes of an optical fiber as free surfaces in the upper neck-down and the tip regions are separately obtained by solving the coupled continuity, momentum, and energy equations. In the upper region simulation, a surface-to-surface radiation model is used for the enclosure which consists of the wall and the glass surface, and the Rosseland approximation radiation model is employed to account for the radiation effect in the glass region. In the tip region simulation, only the glass fiber region is considered and a convective heat transfer model on the fiber surface is employed to account for the energy exchange between the fiber surface and the purge gas. In the fiber, radiation in the axial direction is included. The whole furnace simulation uses a calculated fiber neck-down shape and an assumed fiber tip shape as a fixed interface and computes the convective heat transfer coefficient profile in the tip region which was used in the tip region simulation. The glass viscosity is temperature-dependent and significantly affects the fiber shape. The finite element code FIDAP is used in the study. The effects of various operating conditions such as draw speed, wall temperature distribution, and gas flow rate are studied.

  3. Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores.

    PubMed

    El-Safty, Sherif A; Shenashen, Mohamed A; Sakai, Masaru; Elshehy, Emad; Halada, Kohmei

    2015-12-06

    Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

  4. Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores.

    PubMed

    El-Safty, Sherif A; Shenashen, Mohamed A; Sakai, Masaru; Elshehy, Emad; Halada, Kohmei

    2015-01-01

    Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals. PMID:26709467

  5. Numerical Tool Path Optimization for Conventional Sheet Metal Spinning Processes

    NASA Astrophysics Data System (ADS)

    Rentsch, Benedikt; Manopulo, Niko; Hora, Pavel

    2016-08-01

    To this day, conventional sheet metal spinning processes are designed with a very low degree of automation. They are usually executed by experienced personnel, who actively adjust the tool paths during production. The practically unlimited freedom in designing the tool paths enables the efficient manufacturing of complex geometries on one hand, but is challenging to translate into a standardized procedure on the other. The present study aims to propose a systematic methodology, based on a 3D FEM model combined with a numerical optimization strategy, in order to design tool paths. The accurate numerical modelling of the spinning process is firstly discussed, followed by an analysis of appropriate objective functions and constraints required to obtain a failure free tool path design.

  6. Modeling the electrical resistivity of deformation processed metal-metal composites

    SciTech Connect

    Tian, Liang; Anderson, Iver; Riedemann, Trevor; Russell, Alan

    2014-09-01

    Deformation processed metal–metal (matrix–reinforcement) composites (DMMCs) are high-strength, high-conductivity in situ composites produced by severe plastic deformation. The electrical resistivity of DMMCs is rarely investigated mechanistically and tends to be slightly higher than the rule-of-mixtures prediction. In this paper, we analyze several possible physical mechanisms (i.e. phonons, interfaces, mutual solution, grain boundaries, dislocations) responsible for the electrical resistivity of DMMC systems and how these mechanisms could be affected by processing conditions (i.e. temperature, deformation processing). As an innovation, we identified and assembled the major scattering mechanisms for specific DMMC systems and modeled their electrical resistivity in combination. From this analysis, it appears that filament coarsening rather than dislocation annihilation is primarily responsible for the resistivity drop observed in these materials after annealing and that grain boundary scattering contributes to the resistivity at least at the same magnitude as does interface scattering.

  7. Development of shape memory metal as the actuator of a fail safe mechanism

    NASA Technical Reports Server (NTRS)

    Ford, V. G.; Johnson, M. R.; Orlosky, S. D.

    1990-01-01

    A small, compact, lightweight device was developed using shape memory alloy (SMA) in wire form to actuate a pin-puller that decouples the flanges of two shafts. When the SMA is heated it contracts producing a useful force and stroke. As it cools, it can be reset (elongated in this case) by applying a relatively small force. Resistive heating is accomplished by running a current through the SMA wire for a controlled length of time. The electronics to drive the device are not elaborate or complicated, consisting of a timed current source. The total available contraction is 3 percent of the length of the wire. This device, the engineering properties of the SMA, and the tests performed to verify the design concept are described.

  8. Sensitivity of crescent-shaped metal nanoparticles to attachment of dielectric colloids.

    PubMed

    Unger, Andreas; Rietzler, Uwe; Berger, Rüdiger; Kreiter, Maximilian

    2009-06-01

    The response of the plasmonic resonances of crescent-shaped nanoparticles to the attachment of a dielectric colloidal particle was investigated. The colloid serves as a model analyte which is easy to handle and allows for benchmarking of the sensing capabilities of plasmonic resonators. A clear red shift of the resonances is observed in agreement with the prediction from numerical simulations. From the response for different colloid positions, we obtain information on the nanoscale near field distribution. A field localization to length scales of 20 nm is proven directly. All resonators under study show a comparable response which is important for possible sensing application. We estimate that a further increase of the sensitivity by a factor of 8 would allow for label-free single biomolecule detection.

  9. Microstructure evolution in TRIP-aided seamless steel tube during T-shape hydroforming process

    SciTech Connect

    Liu, Jiyuan; Zhang, Zicheng; Manabe, Ken-ichi; Li, Yanmei; Misra, R.D.K.

    2014-08-15

    Transformation-induced plasticity aided seamless steel tube comprising of ferrite, bainite, and metastable austenite was processed through forging, piercing, cold-drawing, and two-stage heat treatment. T-shape hydroforming is a classic forming method for experimental research and practical production. The current work studied austenite-to-martensite transformation and microcrack initiation and propagation of the tube during T-shape hydroforming using electron backscattering diffraction, scanning electron microscopy, and transmission electron microscopy. The strain distribution in the bcc-phase and fcc-phase was studied by evaluating changes in the average local misorientation. Compared to the compressive stress, metastable austenite with similar strain surrounding or inside the grains transformed easier under tensile loading conditions. The inclusions were responsible for microcrack initiation. The propagation of the cracks is hindered by martensite/austenite constituent due to transformation induced plasticity effect. The volume fraction of untransformed retained austenite decreased with increase in strain implying transformation-induced plasticity effect. - Highlights: • Hydroformed tubes processed via TRIP concept • EBSD provided estimate of micro local strain. • Retained austenite hinders propagation of microcracks.

  10. Highly reliable and bright GaN vertical LED on metal alloy substrate using corrugated pyramid shaped surface technology

    NASA Astrophysics Data System (ADS)

    Chu, Jiunn-Yi; Chu, Chen-Fu; Cheng, Chao-Chen; Liu, Wen-Huan; Cheng, Hao-Chun; Fan, Feng-Hsu; Yen, Jui-Kang; Tran, Chuong Anh; Doan, Trung

    2008-02-01

    GaN vertical LED on metal alloy substrate (VLEDMS) is a desirable technology suitable for solid state lighting application from the viewpoint of reliability and lighting efficacy performance. A new top surface engineering technique for efficient light extraction is employed to VLEDMS to improve power conversion efficiency further. Corrugated pyramid shaped (CPS) surfaces are developed and formed on VLEDMS. By using such structure, VLEDMS exhibit a great enhancement of around 20% in light output power, and a high efficiency of over 100 lumens per watt can also be achieved by white LEDs. In the life test, the light output power of VLEDMS chips drop only by less than 10% within 3,000 hours, and the chips can also endure over 1000 cycles of thermal shocks without significant variations in electro-optical performance. Therefore, the highly reliable and bright VLEDMS using CPS surface engineering technique is very suitable for the solid-state lighting application.

  11. Modeling and FE Simulation of Quenchable High Strength Steels Sheet Metal Hot Forming Process

    NASA Astrophysics Data System (ADS)

    Liu, Hongsheng; Bao, Jun; Xing, Zhongwen; Zhang, Dejin; Song, Baoyu; Lei, Chengxi

    2011-08-01

    High strength steel (HSS) sheet metal hot forming process is investigated by means of numerical simulations. With regard to a reliable numerical process design, the knowledge of the thermal and thermo-mechanical properties is essential. In this article, tensile tests are performed to examine the flow stress of the material HSS 22MnB5 at different strains, strain rates, and temperatures. Constitutive model based on phenomenological approach is developed to describe the thermo-mechanical properties of the material 22MnB5 by fitting the experimental data. A 2D coupled thermo-mechanical finite element (FE) model is developed to simulate the HSS sheet metal hot forming process for U-channel part. The ABAQUS/explicit model is used conduct the hot forming stage simulations, and ABAQUS/implicit model is used for accurately predicting the springback which happens at the end of hot forming stage. Material modeling and FE numerical simulations are carried out to investigate the effect of the processing parameters on the hot forming process. The processing parameters have significant influence on the microstructure of U-channel part. The springback after hot forming stage is the main factor impairing the shape precision of hot-formed part. The mechanism of springback is advanced and verified through numerical simulations and tensile loading-unloading tests. Creep strain is found in the tensile loading-unloading test under isothermal condition and has a distinct effect on springback. According to the numerical and experimental results, it can be concluded that springback is mainly caused by different cooling rats and the nonhomogengeous shrink of material during hot forming process, the creep strain is the main factor influencing the amount of the springback.

  12. Energy Saving Melting and Revert Reduction Technology: Innovative Semi-Solid Metal (SSM) Processing

    SciTech Connect

    Diran Apelian

    2012-08-15

    Semi-solid metal (SSM) processing has emerged as an attractive method for near-net-shape manufacturing due to the distinct advantages it holds over conventional near-net-shape forming technologies. These advantages include lower cycle time, increased die life, reduced porosity, reduced solidification shrinkage, improved mechanical properties, etc. SSM processing techniques can not only produce the complex dimensional details (e.g. thin-walled sections) associated with conventional high-pressure die castings, but also can produce high integrity castings currently attainable only with squeeze and low-pressure permanent mold casting processes. There are two primary semi-solid processing routes, (a) thixocasting and (b) rheocasting. In the thixocasting route, one starts from a non-dendritic solid precursor material that is specially prepared by a primary aluminum manufacturer, using continuous casting methods. Upon reheating this material into the mushy (a.k.a. "two-phase") zone, a thixotropic slurry is formed, which becomes the feed for the casting operation. In the rheocasting route (a.k.a. "slurry-on-demand" or "SoD"), one starts from the liquid state, and the thixotropic slurry is formed directly from the melt via careful thermal management of the system; the slurry is subsequently fed into the die cavity. Of these two routes, rheocasting is favored in that there is no premium added to the billet cost, and the scrap recycling issues are alleviated. The CRP (Trade Marked) is a process where the molten metal flows through a reactor prior to casting. The role of the reactor is to ensure that copious nucleation takes place and that the nuclei are well distributed throughout the system prior to entering the casting cavity. The CRP (Trade Marked) has been successfully applied in hyper-eutectic Al-Si alloys (i.e., 390 alloy) where two liquids of equal or different compositions and temperatures are mixed in the reactor and creating a SSM slurry. The process has been mostly

  13. Removal and recovery of metal ions from process and waste streams using polymer filtration

    SciTech Connect

    Jarvinen, G.D.; Smith, B.F.; Robison, T.W.; Kraus, K.M.; Thompson, J.A.

    1999-06-13

    Polymer Filtration (PF) is an innovative, selective metal removal technology. Chelating, water-soluble polymers are used to selectively bind the desired metal ions and ultrafiltration is used to concentrate the polymer-metal complex producing a permeate with low levels of the targeted metal ion. When applied to the treatment of industrial metal-bearing aqueous process streams, the permeate water can often be reused within the process and the metal ions reclaimed. This technology is applicable to many types of industrial aqueous streams with widely varying chemistries. Application of PF to aqueous streams from nuclear materials processing and electroplating operations will be described.

  14. Design of donor-acceptor star-shaped oligomers for efficient solution-processible organic photovoltaics.

    PubMed

    Ponomarenko, S A; Luponosov, Y N; Min, J; Solodukhin, A N; Surin, N M; Shcherbina, M A; Chvalun, S N; Ameri, T; Brabec, C

    2014-01-01

    This contribution describes recent progress in the design, synthesis and properties of solution-processible star-shaped oligomers and their application in organic photovoltaics. Even though alternative chemistry has been used to design such oligomers, the most successful approach is based on a triphenylamine donor branching center, (oligo)thiophene conjugated spacers and dicyanovinyl acceptor groups. These are mainly amorphous low band-gap organic semiconductors, though crystalline or liquid crystalline ordering can sometimes be realized. It was shown that the solubility, thermal behavior and structure of such molecules in the bulk strongly depend on the presence and position of alkyl groups, as well as on their length. The photovoltaic properties of solution-processed molecules of this type are now approaching 5% which exceeds those of vacuum-sublimed devices. The design rules and future perspectives of this class of organic photovoltaic molecules are discussed. PMID:25277550

  15. Design of donor-acceptor star-shaped oligomers for efficient solution-processible organic photovoltaics.

    PubMed

    Ponomarenko, S A; Luponosov, Y N; Min, J; Solodukhin, A N; Surin, N M; Shcherbina, M A; Chvalun, S N; Ameri, T; Brabec, C

    2014-01-01

    This contribution describes recent progress in the design, synthesis and properties of solution-processible star-shaped oligomers and their application in organic photovoltaics. Even though alternative chemistry has been used to design such oligomers, the most successful approach is based on a triphenylamine donor branching center, (oligo)thiophene conjugated spacers and dicyanovinyl acceptor groups. These are mainly amorphous low band-gap organic semiconductors, though crystalline or liquid crystalline ordering can sometimes be realized. It was shown that the solubility, thermal behavior and structure of such molecules in the bulk strongly depend on the presence and position of alkyl groups, as well as on their length. The photovoltaic properties of solution-processed molecules of this type are now approaching 5% which exceeds those of vacuum-sublimed devices. The design rules and future perspectives of this class of organic photovoltaic molecules are discussed.

  16. Metal-macrocycle framework (MMF): supramolecular nano-channel surfaces with shape sorting capability.

    PubMed

    Tashiro, Shohei; Kubota, Ryou; Shionoya, Mitsuhiko

    2012-02-01

    Hollow nanostructures for the functional assembly of chemical groups with inner surface geometry and regulable stoichiometry enable steric design of interior reaction centers. Herein we report a metal-macrocycle framework (MMF) that forms single-crystalline nanochannels with five distinct enantiomeric pairs of guest binding pockets. During crystal-soaking experiments, the MMF crystals can encapsulate aromatic molecules with high site selectivity. First, constitutional isomers of dibromobenzene are captured and sorted into different binding pockets. Second, each of the optical isomers of (1R/1S)-1-(3-chlorophenyl)ethanol is included diastereoselectively into one of an enantiomeric pair of binding pockets. An advantage of this strategy is that the interior walls can be "repainted" via replacement of the trapped molecules with alternatives. Such guest uptake behaviors would allow highly regioselective or stereoselective reactions within the nanochannel.

  17. Effects of process parameters in plastic, metal, and ceramic injection molding processes

    NASA Astrophysics Data System (ADS)

    Lee, Shi W.; Ahn, Seokyoung; Whang, Chul Jin; Park, Seong Jin; Atre, Sundar V.; Kim, Jookwon; German, Randall M.

    2011-09-01

    Plastic injection molding has been widely used in the past and is a dominant forming approach today. As the customer demands require materials with better engineering properties that were not feasible with polymers, powder injection molding with metal and ceramic powders has received considerable attention in recent decades. To better understand the differences in the plastic injection molding, metal injection molding, and ceramic injection molding, the effects of the core process parameters on the process performances has been studied using the state-of-the-art computer-aided engineering (CAE) design tool, PIMSolver® The design of experiments has been conducted using the Taguchi method to obtain the relative contributions of various process parameters onto the successful operations.

  18. Pyrometallurgical processing of Integral Fast Reactor metal fuels

    SciTech Connect

    Battles, J.E.; Miller, W.E.; Gay, E.C.

    1991-01-01

    The pyrometallurgical process for recycling spent metal fuels from the Integral Fast Reactor is now in an advanced state of development. This process involves electrorefining spent fuel with a cadmium anode, solid and liquid cathodes, and a molten salt electrolyte (LiCl-KCl) at 500{degrees}C. The initial process feasibility and flowsheet verification studies have been conducted in a laboratory-scale electrorefiner. Based on these studies, a dual cathode approach has been adopted, where uranium is recovered on a solid cathode mandrel and uranium-plutonium is recovered in a liquid cadmium cathode. Consolidation and purification (salt and cadmium removal) of uranium and uranium-plutonium products from the electrorefiner have been successful. The process is being developed with the aid of an engineering-scale electrorefiner, which has been successfully operated for more than three years. In this electrorefiner, uranium has been electrotransported from the cadmium anode to a solid cathode in 10 kg quantities. Also, anodic dissolution of 10 kg batches of chopped, simulated fuel (U--10% Zr) has been demonstrated. Development of the liquid cadmium cathode for recovering uranium-plutonium is under way.

  19. Part height control of laser metal additive manufacturing process

    NASA Astrophysics Data System (ADS)

    Pan, Yu-Herng

    Laser Metal Deposition (LMD) has been used to not only make but also repair damaged parts in a layer-by-layer fashion. Parts made in this manner may produce less waste than those made through conventional machining processes. However, a common issue of LMD involves controlling the deposition's layer thickness. Accuracy is important, and as it increases, both the time required to produce the part and the material wasted during the material removal process (e.g., milling, lathe) decrease. The deposition rate is affected by multiple parameters, such as the powder feed rate, laser input power, axis feed rate, material type, and part design, the values of each of which may change during the LMD process. Using a mathematical model to build a generic equation that predicts the deposition's layer thickness is difficult due to these complex parameters. In this thesis, we propose a simple method that utilizes a single device. This device uses a pyrometer to monitor the current build height, thereby allowing the layer thickness to be controlled during the LMD process. This method also helps the LMD system to build parts even with complex parameters and to increase material efficiency.

  20. Optimization of Gas Metal Arc Welding Process Parameters

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Khurana, M. K.; Yadav, Pradeep K.

    2016-09-01

    This study presents the application of Taguchi method combined with grey relational analysis to optimize the process parameters of gas metal arc welding (GMAW) of AISI 1020 carbon steels for multiple quality characteristics (bead width, bead height, weld penetration and heat affected zone). An orthogonal array of L9 has been implemented to fabrication of joints. The experiments have been conducted according to the combination of voltage (V), current (A) and welding speed (Ws). The results revealed that the welding speed is most significant process parameter. By analyzing the grey relational grades, optimal parameters are obtained and significant factors are known using ANOVA analysis. The welding parameters such as speed, welding current and voltage have been optimized for material AISI 1020 using GMAW process. To fortify the robustness of experimental design, a confirmation test was performed at selected optimal process parameter setting. Observations from this method may be useful for automotive sub-assemblies, shipbuilding and vessel fabricators and operators to obtain optimal welding conditions.

  1. The role of rapid solidification processing in the fabrication of fiber reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Locci, Ivan E.; Noebe, Ronald D.

    1989-01-01

    Advanced composite processing techniques for fiber reinforced metal matrix composites require the flexibility to meet several widespread objectives. The development of uniquely desired matrix microstructures and uniformly arrayed fiber spacing with sufficient bonding between fiber and matrix to transmit load between them without degradation to the fiber or matrix are the minimum requirements necessary of any fabrication process. For most applications these criteria can be met by fabricating composite monotapes which are then consolidated into composite panels or more complicated components such as fiber reinforced turbine blades. Regardless of the end component, composite monotapes are the building blocks from which near net shape composite structures can be formed. The most common methods for forming composite monotapes are the powder cloth, foil/fiber, plasma spray, and arc spray processes. These practices, however, employ rapid solidification techniques in processing of the composite matrix phase. Consequently, rapid solidification processes play a vital and yet generally overlooked role in composite fabrication. The future potential of rapid solidification processing is discussed.

  2. Growth and characterization of V-shaped IrO(2) nanowedges via metal-organic vapor deposition.

    PubMed

    Chen, C A; Chen, Y M; Huang, Y S; Tsai, D S; Tiong, K K; Du, C H

    2008-11-19

    We report in detail the synthesis and characterization of V-shaped IrO(2) nanowedges (NWs) with an angle of 110° between the two arms. The NWs were grown on top of rutile (R) phase TiO(2) nanorods (NRs) sitting on a sapphire (SA)(100) substrate via metal-organic chemical vapor deposition (MOCVD) by using (C(6)H(7))(C(8)H(12))Ir and titanium-tetraisopropoxide (TTIP, Ti[OCH(CH(3))(2)](4)) as the source reagents. The surface morphology, structural, and spectroscopic properties of the as-deposited nanocrystals (NCs) were characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), micro-Raman spectroscopy, transmission electron microscopy (TEM), and selected-area electron diffractometry (SAED). The FESEM images and XRD patterns indicated growth of V-shaped IrO(2)(101) NWs on top of R-TiO(2) NRs. The Raman spectrum showed the nanosize induced redshift and peak broadening of the IrO(2) and rutile phase of TiO(2) signatures with respect to that of the bulk counterparts. TEM and SAED characterizations of IrO(2) NCs showed that the nanowedges were crystalline IrO(2) with a twin plane of (101) and twin direction of [Formula: see text] at the V-junction. The probable mechanisms for the formation of well-aligned IrO(2) NWs are discussed. PMID:21836254

  3. Growth and characterization of V-shaped IrO2 nanowedges via metal-organic vapor deposition

    NASA Astrophysics Data System (ADS)

    Chen, C. A.; Chen, Y. M.; Huang, Y. S.; Tsai, D. S.; Tiong, K. K.; Du, C. H.

    2008-11-01

    We report in detail the synthesis and characterization of V-shaped IrO2 nanowedges (NWs) with an angle of 110° between the two arms. The NWs were grown on top of rutile (R) phase TiO2 nanorods (NRs) sitting on a sapphire (SA)(100) substrate via metal-organic chemical vapor deposition (MOCVD) by using (C6H7)(C8H12)Ir and titanium-tetraisopropoxide (TTIP, Ti[OCH(CH3)2]4) as the source reagents. The surface morphology, structural, and spectroscopic properties of the as-deposited nanocrystals (NCs) were characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), micro-Raman spectroscopy, transmission electron microscopy (TEM), and selected-area electron diffractometry (SAED). The FESEM images and XRD patterns indicated growth of V-shaped IrO2(101) NWs on top of R-TiO2 NRs. The Raman spectrum showed the nanosize induced redshift and peak broadening of the IrO2 and rutile phase of TiO2 signatures with respect to that of the bulk counterparts. TEM and SAED characterizations of IrO2 NCs showed that the nanowedges were crystalline IrO2 with a twin plane of (101) and twin direction of [\\bar {1} 01] at the V-junction. The probable mechanisms for the formation of well-aligned IrO2 NWs are discussed.

  4. Adsorption of volatile organic compounds by metal-organic frameworks MIL-101: influence of molecular size and shape.

    PubMed

    Yang, Kun; Sun, Qian; Xue, Feng; Lin, Daohui

    2011-11-15

    Adsorption of gaseous volatile organic compounds (VOCs) on metal-organic frameworks MIL-101, a novel porous adsorbent with extremely large Langmuir surface area of 5870 m(2)/g and pore volume of 1.85 cm(3)/g, and the influence of VOC molecular size and shape on adsorption were investigated in this study. We observed that MIL-101 is a potential superior adsorbent for the sorptive removal of VOCs including polar acetone and nonpolar benzene, toluene, ethylbeznene, and xylenes. MIL-101 is of higher adsorption capacities for all selected VOCs than zeolite, activated carbon and other reported adsorbents. Adsorption of VOCs on MIL-101 is captured by a pore filling mechanism, showing the size and shape selectivity of VOC molecules. These prove to be a negative linear relationship between the volume adsorption capacities of VOCs and their molecular cross-sectional area values. Most VOC molecules, such as acetone, benzene, toluene, ethylbenzene and p-xylene, enter into MIL-101 pores with the planes having the minimum diameters. However, m-xylene and o-xylene may fill into the pores with the planes having the maximum diameters because of the preferred interaction of MIL-101 with the two methyl groups of adsorbate molecules.

  5. Studies on the effect of grain refinement and thermal processing on shape memory characteristics of Cu Al Ni alloys

    NASA Astrophysics Data System (ADS)

    Sampath, V.

    2005-10-01

    Though Ni-Ti shape memory alloys are used extensively in a variety of engineering and medical applications because of their attractive shape memory characteristics, they still suffer from certain drawbacks, such as low transformation temperatures, difficulty in production and processing and high cost of raw materials. Copper-based alloys have, therefore, come as an alternative to Ni-Ti shape memory alloys. They are easier to produce and process and are also less expensive. They are used where Ni-Ti alloys cannot be used. But Cu-Al-Ni shape memory alloys also pose problems since they are brittle and possess lower shape recovery strains and stresses. With a view to increasing the shape memory characteristics and ductility of Cu-Al-Ni shape memory alloys, they were subjected to grain refinement and thermomechanical processing. The present study establishes that grain-refining additions result in considerable reduction in the grain size of the alloys. In addition, grain refinement and alloying cause an increase in the transformation temperatures. The results are analysed in the light of the explanations/theories put forth in recent papers related to Cu-Al-Ni shape memory alloys, and an attempt has been made to compare the results.

  6. Standard for metal/nonmetal mining and metal mineral processing facilities. 2004 ed.

    SciTech Connect

    2004-07-01

    This standard addresses the protection of diesel-powered equipment and the storage and handling of flammable and combustible liquids at these specialized sites. The 2004 edition consolidates requirements from NFPA 122 and 121 : Standard on Fire Protection for Self-Propelled and Mobile Surface Mining Equipment. Major changes include a new chapter on fire protection of surface metal mineral processing plants. The Standard is also revised to emphasize the use of a fire risk assessment when determining fire protection criteria. Chapter headings are: Administration; Referenced publications; Definitions; General; Fire risk assessment and risk reduction; Fire detection and suppression equipment; Fire protection for diesel-powered equipment in underground mines; Transfer of flammable or combustible liquids in underground mines; Flammable liquid storage in underground mines; Combustible liquid storage in underground mines; Fire suppression for flammable or combustible liquid storage areas in underground mines; Fire protection of surface mobile and self-propelled equipment; and Fire protection of surface metal mineral processing plants. 3 annexes.

  7. Development of a Methodology for Conducting Hall Thruster EMI Tests in Metal Vacuum Chambers of Arbitrary Shape and Size

    NASA Technical Reports Server (NTRS)

    Gallimore, Alec D.

    2000-01-01

    While the closed-drift Hall thruster (CDT) offers significant improvement in performance over conventional chemical rockets and other advanced propulsion systems such as the arcjet, its potential impact on spacecraft communication signals must be carefully assessed before widespread use of this device can take place. To this end, many of the potentially unique issues that are associated with these thrusters center on its plume plasma characteristics and the its interaction with electromagnetic waves. Although a great deal of experiments have been made in characterizing the electromagnetic interference (EMI) potential of these thrusters, the interpretation of the resulting data is difficult because most of these measurements have been made in vacuum chambers with metal walls which reflect radio waves emanating from the thruster. This project developed a means of assessing the impact of metal vacuum chambers of arbitrary size or shape on EMI experiments, thereby allowing for test results to be interpreted properly. Chamber calibration techniques were developed and initially tested at RIAME using their vacuum chamber. Calibration experiments were to have been made at Tank 5 of NASA GRC and the 6 m by 9 m vacuum chamber at the University of Michigan to test the new procedure, however the subcontract to RIAME was cancelled by NASA memorandum on Feb. 26. 1999.

  8. Experimental Methods for Investigation of Shape Memory Based Elastocaloric Cooling Processes and Model Validation.

    PubMed

    Schmidt, Marvin; Ullrich, Johannes; Wieczorek, André; Frenzel, Jan; Eggeler, Gunther; Schütze, Andreas; Seelecke, Stefan

    2016-01-01

    Shape Memory Alloys (SMA) using elastocaloric cooling processes have the potential to be an environmentally friendly alternative to the conventional vapor compression based cooling process. Nickel-Titanium (Ni-Ti) based alloy systems, especially, show large elastocaloric effects. Furthermore, exhibit large latent heats which is a necessary material property for the development of an efficient solid-state based cooling process. A scientific test rig has been designed to investigate these processes and the elastocaloric effects in SMAs. The realized test rig enables independent control of an SMA's mechanical loading and unloading cycles, as well as conductive heat transfer between SMA cooling elements and a heat source/sink. The test rig is equipped with a comprehensive monitoring system capable of synchronized measurements of mechanical and thermal parameters. In addition to determining the process-dependent mechanical work, the system also enables measurement of thermal caloric aspects of the elastocaloric cooling effect through use of a high-performance infrared camera. This combination is of particular interest, because it allows illustrations of localization and rate effects - both important for efficient heat transfer from the medium to be cooled. The work presented describes an experimental method to identify elastocaloric material properties in different materials and sample geometries. Furthermore, the test rig is used to investigate different cooling process variations. The introduced analysis methods enable a differentiated consideration of material, process and related boundary condition influences on the process efficiency. The comparison of the experimental data with the simulation results (of a thermomechanically coupled finite element model) allows for better understanding of the underlying physics of the elastocaloric effect. In addition, the experimental results, as well as the findings based on the simulation results, are used to improve the

  9. Experimental Methods for Investigation of Shape Memory Based Elastocaloric Cooling Processes and Model Validation.

    PubMed

    Schmidt, Marvin; Ullrich, Johannes; Wieczorek, André; Frenzel, Jan; Eggeler, Gunther; Schütze, Andreas; Seelecke, Stefan

    2016-01-01

    Shape Memory Alloys (SMA) using elastocaloric cooling processes have the potential to be an environmentally friendly alternative to the conventional vapor compression based cooling process. Nickel-Titanium (Ni-Ti) based alloy systems, especially, show large elastocaloric effects. Furthermore, exhibit large latent heats which is a necessary material property for the development of an efficient solid-state based cooling process. A scientific test rig has been designed to investigate these processes and the elastocaloric effects in SMAs. The realized test rig enables independent control of an SMA's mechanical loading and unloading cycles, as well as conductive heat transfer between SMA cooling elements and a heat source/sink. The test rig is equipped with a comprehensive monitoring system capable of synchronized measurements of mechanical and thermal parameters. In addition to determining the process-dependent mechanical work, the system also enables measurement of thermal caloric aspects of the elastocaloric cooling effect through use of a high-performance infrared camera. This combination is of particular interest, because it allows illustrations of localization and rate effects - both important for efficient heat transfer from the medium to be cooled. The work presented describes an experimental method to identify elastocaloric material properties in different materials and sample geometries. Furthermore, the test rig is used to investigate different cooling process variations. The introduced analysis methods enable a differentiated consideration of material, process and related boundary condition influences on the process efficiency. The comparison of the experimental data with the simulation results (of a thermomechanically coupled finite element model) allows for better understanding of the underlying physics of the elastocaloric effect. In addition, the experimental results, as well as the findings based on the simulation results, are used to improve the

  10. Optimized process parameters for fabricating metal particles reinforced 5083 Al composite by friction stir processing

    PubMed Central

    Bauri, Ranjit; Yadav, Devinder; Shyam Kumar, C.N.; Janaki Ram, G.D.

    2015-01-01

    Metal matrix composites (MMCs) exhibit improved strength but suffer from low ductility. Metal particles reinforcement can be an alternative to retain the ductility in MMCs (Bauri and Yadav, 2010; Thakur and Gupta, 2007) [1,2]. However, processing such composites by conventional routes is difficult. The data presented here relates to friction stir processing (FSP) that was used to process metal particles reinforced aluminum matrix composites. The data is the processing parameters, rotation and traverse speeds, which were optimized to incorporate Ni particles. A wide range of parameters covering tool rotation speeds from 1000 rpm to 1800 rpm and a range of traverse speeds from 6 mm/min to 24 mm/min were explored in order to get a defect free stir zone and uniform distribution of particles. The right combination of rotation and traverse speed was found from these experiments. Both as-received coarse particles (70 μm) and ball-milled finer particles (10 μm) were incorporated in the Al matrix using the optimized parameters. PMID:26566541

  11. Molten metal processing of advanced cast aluminum alloys

    NASA Astrophysics Data System (ADS)

    Shivkumar, S.; Wang, L.; Apelian, D.

    1991-01-01

    Premium quality aluminum alloy castings are used extensively in various applications requiring a high strength-to-weight ratio, such as aerospace, automotive and other structural components. The mechanical properties in these structure-sensitive alloys are determined primarily by the secondary dendrite arm spacing and the morphology of interdendritic phases. In addition, the amount of porosity in the casting and the inclusion concentration have a strong influence on fracture, fatigue and impact properties. During the production of the casting, various molten metal processing techniques can be implemented to control these microstructural parameters. These melt treatments include grain refinement with Ti-B, eutectic modification with strontium or sodium, degassing with purge gases and filtration of inclusions. The efficiency of these treatments determines the quality of the cast component.

  12. Near net shape forming processes for chemically prepared zinc oxide varistors.

    SciTech Connect

    Lockwood, Steven John; Voigt, James A.; Tuttle, Bruce Andrew; Bell, Nelson Simmons

    2005-01-01

    Chemically prepared zinc oxide powders are fabricated for the production of high aspect ratio varistor components. Colloidal processing in water was performed to reduce agglomerates to primary particles, form a high solids loading slurry, and prevent dopant migration. The milled and dispersed powder exhibited a viscoelastic to elastic behavioral transition at a volume loading of 43-46%. The origin of this transition was studied using acoustic spectroscopy, zeta potential measurements and oscillatory rheology. The phenomenon occurs due to a volume fraction solids dependent reduction in the zeta potential of the solid phase. It is postulated to result from divalent ion binding within the polyelectrolyte dispersant chain, and was mitigated using a polyethylene glycol plasticizing additive. Chemically prepared zinc oxide powders were processed for the production of high aspect ratio varistor components. Near net shape casting methods including slip casting and agarose gelcasting were evaluated for effectiveness in achieving a uniform green microstructure achieving density values near the theoretical maximum during sintering. The structure of the green parts was examined by mercury porisimetry. Agarose gelcasting produced green parts with low solids loading values and did not achieve high fired density. Isopressing the agarose cast parts after drying raised the fired density to greater than 95%, but the parts exhibited catastrophic shorting during electrical testing. Slip casting produced high green density parts, which exhibited high fired density values. The electrical characteristics of slip cast parts are comparable with dry pressed powder compacts. Alternative methods for near net shape forming of ceramic dispersions were investigated for use with the chemically prepared ZnO material. Recommendations for further investigation to achieve a viable production process are presented.

  13. Process for metallization of a substrate by irradiative curing of a catalyst applied thereto

    DOEpatents

    Chen, Ken S.; Morgan, William P.; Zich, John L.

    1999-01-01

    An improved additive process for metallization of substrates is described whereby a catalyst solution is applied to a surface of a substrate. Metallic catalytic clusters can be formed in the catalyst solution on the substrate surface by irradiating the substrate. Electroless plating can then deposit metal onto the portion of the substrate surface having metallic clusters. Additional metallization thickness can be obtained by electrolytically plating the substrate surface after the electroless plating step.

  14. Spallation in metallic systems: Effects of microstructure, and loading pulse shape, rate and orientation

    NASA Astrophysics Data System (ADS)

    Luo, S. N.

    2011-06-01

    The dynamic nature of spallation and the ubiquitous presence of microstructure may give rise to significant dependences on microstructure and loading, as indicated by indirect experimental observations. We present systematic, direct molecular dynamics (MD) simulations of spallation in metallic systems represented by Cu and a CuZr glass. The ``microstructure'' includes various defects in Cu, porous Cu, atomic-level inhomogeneities in the CuZr glass, and the Cu crystal -CuZr glass interfaces. We explore supported and decaying shock loading pulses, as well as different loading orientations. Tensile loading rates are changed via varying the flyer and target thicknesses in shock simulations, and more significantly (down to ~106 s-1), with accelerated MD simulations of single-void growth in Cu (mimicking shock). Our direct simulations reveal strong dependences of spallation on microstructure and loading, and quantitative dynamics of void nucleation/growth as well as mechanisms for plasticity, void nucleation and their interactions in the absence or presence of defects or interfaces. The future task of incorporating statistically the microstructure effects and their rate dependences into analytic models is of great interest to shock physics but a challenge. Work done in collaboration with T.C. Germann, D. Perez, Q. An, B. Arman, W.Z. Han, D.L. Tonks, J.E. Hammerberg, A.F. Voter, Los Alamos National Laboratory; W.A. Goddard III, Caltech; and T. Cagin, Texas A & M University.

  15. T-shaped emitter metal heterojunction bipolar transistors for submillimeter wave applications

    NASA Technical Reports Server (NTRS)

    Fung, Andy; Samoska, Lorene; Velebir, Jim; Siege, Peter; Rodwell, Mark; Paidi, Vamsi; Griffth, Zach; Urteaga, Miguel; Malik, Roger

    2004-01-01

    We report on the development of submillimeter wave transistors at JPL. The goal of the effort is to produce advance-reliable high frequency and high power amplifiers, voltage controlled oscillators, active multipliers, and high-speed mixed-signal circuits for space borne applications. The technology in development to achieve this is based on the Indium Phosphide (InP) Heterojunction Bipolar Transistor (HBT). The HBT is well suited for high speed, high power and uniform (across wafer) performance, due to the ability to tailor the material structure that electrons traverse through by well-controlled epitaxial growth methods. InP with its compatible lattice matched alloys such as indium gallium arsenide (InGaAs) and indium aluminium arsenide (InAlAs) provides for high electron velocities and high voltage breakdown capabilities. The epitaxial methods for this material system are fairly mature, however the implementation of high performance and reliable transistors are still under development by many laboratories. Our most recently fabricated, second generation mesa HBTs at JPL have extrapolated current gain cutoff frequency (FJ of 142GHz and power gain cutoff frequency (Fm,) of approximately 160GHz. This represents a 13% and 33% improvement of Ft and F, respectively, compared to the first generation mesa HBTs [l]. Analysis based on the University of California, Santa Barbara (UCSB) device model, RF device characteristics can be significantly improved by reducing base contact resistance and base metal contact width. We will describe our effort towards increasing transistor performance and yield.

  16. Metal spray apparatus with a U-shaped electric inlet gas heater and a one-piece electric heater surrounding a nozzle

    DOEpatents

    Glovan, Ronald J.; Tierney, John C.; McLean, Leroy L.; Johnson, Lawrence L.; Verbael, David J.

    1995-01-01

    An electrically heated metal spray apparatus is provided with a supersonic nozzle. Molten metal is injected into a gas stream flowing through the nozzle under pressure. By varying the pressure of the injected metal, the droplet can be made in various selected sizes with each selected size having a high degree of size uniformity. A unique one piece graphite heater provides easily controlled uniformity of temperature in the nozzle and an attached tundish which holds the pressurized molten metal. A unique U-shaped gas heater provides extremely hot inlet gas temperatures to the nozzle. A particularly useful application of the spray apparatus is coating of threads of a fastener with a shape memory alloy. This permits a fastener to be easily inserted and removed but provides for a secure locking of the fastener in high temperature environments.

  17. Metal spray apparatus with a U-shaped electric inlet gas heater and a one-piece electric heater surrounding a nozzle

    DOEpatents

    Glovan, R.J.; Tierney, J.C.; McLean, L.L.; Johnson, L.L.; Verbael, D.J.

    1995-10-17

    An electrically heated metal spray apparatus is provided with a supersonic nozzle. Molten metal is injected into a gas stream flowing through the nozzle under pressure. By varying the pressure of the injected metal, the droplet can be made in various selected sizes with each selected size having a high degree of size uniformity. A unique one piece graphite heater provides easily controlled uniformity of temperature in the nozzle and an attached tundish which holds the pressurized molten metal. A unique U-shaped gas heater provides extremely hot inlet gas temperatures to the nozzle. A particularly useful application of the spray apparatus is coating of threads of a fastener with a shape memory alloy. This permits a fastener to be easily inserted and removed but provides for a secure locking of the fastener in high temperature environments. 12 figs.

  18. Modeling and Characterization of Damage Processes in Metallic Materials

    NASA Technical Reports Server (NTRS)

    Glaessgen, E. H.; Saether, E.; Smith, S. W.; Hochhalter, J. D.; Yamakov, V. I.; Gupta, V.

    2011-01-01

    This paper describes a broad effort that is aimed at understanding the fundamental mechanisms of crack growth and using that understanding as a basis for designing materials and enabling predictions of fracture in materials and structures that have small characteristic dimensions. This area of research, herein referred to as Damage Science, emphasizes the length scale regimes of the nanoscale and the microscale for which analysis and characterization tools are being developed to predict the formation, propagation, and interaction of fundamental damage mechanisms. Examination of nanoscale processes requires atomistic and discrete dislocation plasticity simulations, while microscale processes can be examined using strain gradient plasticity, crystal plasticity and microstructure modeling methods. Concurrent and sequential multiscale modeling methods are being developed to analytically bridge between these length scales. Experimental methods for characterization and quantification of near-crack tip damage are also being developed. This paper focuses on several new methodologies in these areas and their application to understanding damage processes in polycrystalline metals. On-going and potential applications are also discussed.

  19. Entrenched metal lift-off using a novel bilayer process

    NASA Astrophysics Data System (ADS)

    Dubois, Thomas D.; Tranjan, Farid M.; Jones, Susan K.; Bobbio, Stephen M.; Kellam, Mark D.; Frieser, Rudolph G.; Jones, A. D.

    1990-01-01

    This paper will discuss the preparation and characterization of a modified photoresist and describe its use in a novel bilayer process. The modified photoresist solutions are prepared by dissolving enough cyclic phosphonitrilic chloride trimer, PNCT, in commercially available photoresist solutions to achieve phosphorus concentrations of 10 to 12 weight percent in the resulting films. FTNMR and FTIR data will be presented which demonstrate that the cyclic phosphonitrilic chloride trimer does not undergo chemical reaction with the components of the photoresist in the photoresist solutions or photoresist films. The exposure threshold of the PNCT modified photoresist films is 1.5 times greater than that of the unmodified films. Experimental data will be discussed which suggests the decrease in exposure threshold is the result of a relatively lower concentration of photoactive compound in the PNCT modified films. The PNCT modified films will be shown to provide resolution comparable to that of the unmodified photoresist films and yield a process window of better than 20%. A mechanism for the formation of the 02/N2 plasma resistant etch barrier formed during 02/N2 plasma etching will be discussed. Finally, a bilayer process which uses the PNCT modified photoresist in generating metal features entrenched in polyimide will be presented.

  20. Ultrafast laser spatial beam shaping based on Zernike polynomials for surface processing.

    PubMed

    Houzet, J; Faure, N; Larochette, M; Brulez, A-C; Benayoun, S; Mauclair, C

    2016-03-21

    In femtosecond laser machining, spatial beam shaping can be achieved with wavefront modulators. The wavefront modulator displays a pre-calculated phase mask that modulates the laser wavefront to generate a target intensity distribution in the processing plane. Due to the non-perfect optical response of wavefront modulators, the experimental distribution may significantly differ from the target, especially for continuous shapes. We propose an alternative phase mask calculation method that can be adapted to the phase modulator optical performance. From an adjustable number of Zernike polynomials according to this performance, a least square fitting algorithm numerically determines their coefficients to obtain the desired wavefront modulation. We illustrate the technique with an optically addressed liquid-crystal light valve to produce continuous intensity distributions matching a desired ablation profile, without the need of a wavefront sensor. The projection of the experimental laser distribution shows a 5% RMS error compared to the calculated one. Ablation of steel is achieved following user-defined micro-dimples and micro-grooves targets on mold surfaces. The profiles of the microgrooves and the injected polycarbonate closely match the target (RMS below 4%). PMID:27136844

  1. Salts of alkali metal anions and process of preparing same

    DOEpatents

    Dye, James L.; Ceraso, Joseph M.; Tehan, Frederick J.; Lok, Mei Tak

    1978-01-01

    Compounds of alkali metal anion salts of alkali metal cations in bicyclic polyoxadiamines are disclosed. The salts are prepared by contacting an excess of alkali metal with an alkali metal dissolving solution consisting of a bicyclic polyoxadiamine in a suitable solvent, and recovered by precipitation. The salts have a gold-color crystalline appearance and are stable in a vacuum at -10.degree. C. and below.

  2. Modeling of metal/pattern replacement in the lost foam casting process

    NASA Astrophysics Data System (ADS)

    Molibog, Taras Vitalyevich

    The Lost Foam Casting Process (LFCP), which employs expanded foam patterns placed in unbonded sand, is increasingly gaining popularity in the foundry industry. The time and cost associated with introducing new Lost Foam (LF) castings into production could be significantly reduced by using simulation codes capable of modeling metal fill and solidification and predicting defect formation. The development of accurate models of Lost Foam casting (LFC) has been hindered by a lack of understanding and data on the mechanism of metal/pattern exchange. This research work focused on developing a mathematical model of metal/pattern exchange and generating pattern and glue degradation data necessary for the model. The experimental work was conducted using the foam pyrolysis apparatus developed earlier in this research and included experiments to (a) evaluate the effects of the heater size and shape on foam pyrolysis, (b) observe the morphology of the heater/pattern interface, (c) extend the temperature capabilities of the foam pyrolysis apparatus to iron and steel pouring temperatures of 1600°C (2910°F), (d) measure the temperature of the gaseous degradation products of expanded polystyrene (EPS) exiting the kinetic zone (KZ), (e) measure the EPS degradation resistance pressure and the molecular weight of EPS liquid degradation products, and (f) develop quantitative glue joint degradation data. A simplified mathematical model of heat and mass transfer in the KZ was developed to calculate data necessary to predict the pattern resistance to metal flow. KZ parameters, including KZ thickness and temperature, density and viscosity of degradation products, and heat flux, were calculated for aluminum casting conditions using experimental pattern degradation data. The predicted heat flux values showed good agreement with measured. Modeling of different aspects of LFC, such as fluid flow, heat transfer, and defect formation, is discussed.

  3. Sequential Filtering Processes Shape Feature Detection in Crickets: A Framework for Song Pattern Recognition

    PubMed Central

    Hedwig, Berthold G.

    2016-01-01

    Intraspecific acoustic communication requires filtering processes and feature detectors in the auditory pathway of the receiver for the recognition of species-specific signals. Insects like acoustically communicating crickets allow describing and analysing the mechanisms underlying auditory processing at the behavioral and neural level. Female crickets approach male calling song, their phonotactic behavior is tuned to the characteristic features of the song, such as the carrier frequency and the temporal pattern of sound pulses. Data from behavioral experiments and from neural recordings at different stages of processing in the auditory pathway lead to a concept of serially arranged filtering mechanisms. These encompass a filter for the carrier frequency at the level of the hearing organ, and the pulse duration through phasic onset responses of afferents and reciprocal inhibition of thoracic interneurons. Further, processing by a delay line and coincidence detector circuit in the brain leads to feature detecting neurons that specifically respond to the species-specific pulse rate, and match the characteristics of the phonotactic response. This same circuit may also control the response to the species-specific chirp pattern. Based on these serial filters and the feature detecting mechanism, female phonotactic behavior is shaped and tuned to the characteristic properties of male calling song. PMID:26941647

  4. Looking through phonological shape to lexical meaning: the bottleneck of non-native sign language processing.

    PubMed

    Mayberry, R I; Fischer, S D

    1989-11-01

    In two studies, we find that native and non-native acquisition show different effects on sign language processing. Subjects were all born deaf and used sign language for interpersonal communication, but first acquired it at ages ranging from birth to 18. In the first study, deaf signers shadowed (simultaneously watched and reproduced) sign language narratives given in two dialects, American Sign Language (ASL) and Pidgin Sign English (PSE), in both good and poor viewing conditions. In the second study, deaf signers recalled and shadowed grammatical and ungrammatical ASL sentences. In comparison with non-native signers, natives were more accurate, comprehended better, and made different kinds of lexical changes; natives primarily changed signs in relation to sign meaning independent of the phonological characteristics of the stimulus. In contrast, non-native signers primarily changed signs in relation to the phonological characteristics of the stimulus independent of lexical and sentential meaning. Semantic lexical changes were positively correlated to processing accuracy and comprehension, whereas phonological lexical changes were negatively correlated. The effects of non-native acquisition were similar across variations in the sign dialect, viewing condition, and processing task. The results suggest that native signers process lexical structural automatically, such that they can attend to and remember lexical and sentential meaning. In contrast, non-native signers appear to allocate more attention to the task of identifying phonological shape such that they have less attention available for retrieval and memory of lexical meaning.

  5. Sequential Filtering Processes Shape Feature Detection in Crickets: A Framework for Song Pattern Recognition.

    PubMed

    Hedwig, Berthold G

    2016-01-01

    Intraspecific acoustic communication requires filtering processes and feature detectors in the auditory pathway of the receiver for the recognition of species-specific signals. Insects like acoustically communicating crickets allow describing and analysing the mechanisms underlying auditory processing at the behavioral and neural level. Female crickets approach male calling song, their phonotactic behavior is tuned to the characteristic features of the song, such as the carrier frequency and the temporal pattern of sound pulses. Data from behavioral experiments and from neural recordings at different stages of processing in the auditory pathway lead to a concept of serially arranged filtering mechanisms. These encompass a filter for the carrier frequency at the level of the hearing organ, and the pulse duration through phasic onset responses of afferents and reciprocal inhibition of thoracic interneurons. Further, processing by a delay line and coincidence detector circuit in the brain leads to feature detecting neurons that specifically respond to the species-specific pulse rate, and match the characteristics of the phonotactic response. This same circuit may also control the response to the species-specific chirp pattern. Based on these serial filters and the feature detecting mechanism, female phonotactic behavior is shaped and tuned to the characteristic properties of male calling song.

  6. Process for treating waste water having low concentrations of metallic contaminants

    SciTech Connect

    Looney, Brian B; Millings, Margaret R; Nichols, Ralph L; Payne, William L

    2014-12-16

    A process for treating waste water having a low level of metallic contaminants by reducing the toxicity level of metallic contaminants to an acceptable level and subsequently discharging the treated waste water into the environment without removing the treated contaminants.

  7. Profiling the Phonological Processes Shaping the Fossilized IL of Adult Learners of English as a Foreign Language: Some Theoretical Implications.

    ERIC Educational Resources Information Center

    Monroy, Rafael

    2001-01-01

    Describes the frozen interlanguage (IL) of adult learners of English in a natural setting to profile phonological processes that underlie their output. Also examines the impact on learners' oral behavior and the role played by transfer and developmental processes in such behavior. Analysis yields 10 processes shaping learners' IL that are…

  8. General classification of maturation reaction-norm shape from size-based processes.

    PubMed

    Christensen, Asbjorn; Andersen, Ken Haste

    2011-05-01

    Phenotypic plasticity of size at maturation is commonly described using size-age maturation reaction norms (MRNs). MRNs for age and size at maturation are analyzed and classified into three general categories related to different size scalings of growth and mortality. The underlying model for growth and mortality is based on processes at the level of the individual, and is motivated by the energy budget of fish. MRN shape is a balance between opposing factors and depends on subtle details of size dependence of growth and mortality. MRNs with both positive and negative slopes are predicted, and for certain mortality conditions also a lower critical spawning mass. The model is applied to predict a generic fishery-induced evolutionary response and allows assessment of climate change impact on MRNs. Our work stresses the importance of using realistic size dependence of mortality and growth, since this strongly influences the predicted MRNs and sensitivity to harvest pressure.

  9. Laser shock peening and warm laser shock peening: process modeling and pulse shape influence

    NASA Astrophysics Data System (ADS)

    Fortunato, Alessandro; Orazi, Leonardo; Cuccolini, Gabriele; Ascari, Alessandro

    2013-02-01

    Laser shock peening is a well-known technology able to enhance the fatigue life of mechanical components by means of the introduction of residual stresses on their surface. These stresses are induced by means of the recoil pressure caused by the abrupt expansion, in a confining medium, of a laser-vaporized coating layer. If high power densities are used the recoil pressure can be high enough to induce compressive residual stresses on the target surface and to modify its mechanical properties. These mechanical properties can be predicted if the recoil pressure of the ablating layer is determined. In this paper the influence of the laser pulse shape on the recoil pressure is determined by means of a proper modeling of the whole process and the difference between cold" and warm" laser shock peening is pointed out.

  10. A Springback Compensation Method for Complex-Shaped Flange Components in Fluid-Cell Forming Process

    NASA Astrophysics Data System (ADS)

    Li, Xiaoqiang; Li, Dongsheng; Yang, Weijun

    2011-08-01

    The fluid-cell forming process (FFP), one of the main forming technologies in aeronautical manufactories, suffers seriously from the product quality problem due to springback. A springback compensation method is proposed particularly for complex-shaped flange parts. This method is derived from the classic displacement adjustment method, but differs in the way to predict the springback amount and calculate the adjusting vectors. Based on discussion on the relationship between the springback angles and the geometrical parameters of flange parts, a springback distribution function (SDF) is proposed to predict springback angles of curved flanges. The springback angles are mapped to nodal adjusting vectors of the die mesh and then the optimized die is obtained. The above procedures are applied to two fuselage flange parts and the experimental result shows that this method is valid.

  11. High Throughput Atomic Layer Deposition Processes: High Pressure Operations, New Reactor Designs, and Novel Metal Processing

    NASA Astrophysics Data System (ADS)

    Mousa, MoatazBellah Mahmoud

    Atomic Layer Deposition (ALD) is a vapor phase nano-coating process that deposits very uniform and conformal thin film materials with sub-angstrom level thickness control on various substrates. These unique properties made ALD a platform technology for numerous products and applications. However, most of these applications are limited to the lab scale due to the low process throughput relative to the other deposition techniques, which hinders its industrial adoption. In addition to the low throughput, the process development for certain applications usually faces other obstacles, such as: a required new processing mode (e.g., batch vs continuous) or process conditions (e.g., low temperature), absence of an appropriate reactor design for a specific substrate and sometimes the lack of a suitable chemistry. This dissertation studies different aspects of ALD process development for prospect applications in the semiconductor, textiles, and battery industries, as well as novel organic-inorganic hybrid materials. The investigation of a high pressure, low temperature ALD process for metal oxides deposition using multiple process chemistry revealed the vital importance of the gas velocity over the substrate to achieve fast depositions at these challenging processing conditions. Also in this work, two unique high throughput ALD reactor designs are reported. The first is a continuous roll-to-roll ALD reactor for ultra-fast coatings on porous, flexible substrates with very high surface area. While the second reactor is an ALD delivery head that allows for in loco ALD coatings that can be executed under ambient conditions (even outdoors) on large surfaces while still maintaining very high deposition rates. As a proof of concept, part of a parked automobile window was coated using the ALD delivery head. Another process development shown herein is the improvement achieved in the selective synthesis of organic-inorganic materials using an ALD based process called sequential vapor

  12. System and process for aluminization of metal-containing substrates

    SciTech Connect

    Chou, Yeong-Shyung; Stevenson, Jeffry W

    2015-11-03

    A system and method are detailed for aluminizing surfaces of metallic substrates, parts, and components with a protective alumina layer in-situ. Aluminum (Al) foil sandwiched between the metallic components and a refractory material when heated in an oxidizing gas under a compression load at a selected temperature forms the protective alumina coating on the surface of the metallic components. The alumina coating minimizes evaporation of volatile metals from the metallic substrates, parts, and components in assembled devices during operation at high temperature that can degrade performance.

  13. Process for the preparation of metal-containing nanostructured films

    NASA Technical Reports Server (NTRS)

    Lu, Yunfeng (Inventor); Wang, Donghai (Inventor)

    2006-01-01

    Metal-containing nanostructured films are prepared by electrodepositing a metal-containing composition within the pores of a mesoporous silica template to form a metal-containing silica nanocomposite. The nanocomposite is annealed to strengthen the deposited metal-containing composition. The silica is then removed from the nanocomposite, e.g., by dissolving the silica in an etching solution to provide a self-supporting metal-containing nanostructured film. The nanostructured films have a nanowire or nanomesh architecture depending on the pore structure of the mesoporous silica template used to prepare the films.

  14. Missing the Big Picture: Impaired Development of Global Shape Processing in Autism

    PubMed Central

    Scherf, K. Suzanne; Luna, Beatriz; Kimchi, Ruth; Minshew, Nancy; Behrmann, Marlene

    2009-01-01

    Individuals with autism exhibit hypersensitivity to local elements of the input, which may interfere with the ability to group visual elements perceptually. We investigated the development of perceptual grouping abilities in high-functioning individuals with autism (HFA) across a wide age range (8–30 years) using a classic compound letter global/ local (GL) task and a more fine-grained microgenetic prime paradigm (MPP), including both few- and many-element hierarchical displays. In the GL task, contrary to the typically developing (TD) controls, HFA participants did not develop an increasing sensitivity to the global information with age. In the MPP, like the TD controls, individuals with autism at all three age groups evinced a bias to individuate the few-element displays. However, contrary to the TD controls, the HFA group failed to show age-related improvements in the ability to encode the global shape of the many-element displays. In fact, across the age range, the HFA group was consistently faster than the TD controls at perceiving the local elements in these displays. These results indicate that in autism the full process of garnering shape information from perceptual grouping, which is essential for the ability to do fast and efficient object recognition and identification, never matures, and this is especially evident in adolescence when this ability begins to improve in TD individuals. The atypical development of these perceptual organizational abilities may disrupt processing of visually presented objects, which may, in turn, fundamentally impede the development of major aspects of the social and emotional behaviors in individuals with autism. PMID:19360658

  15. Half-Collision Dynamics of Excited Metal Atom Quenching Processes

    NASA Astrophysics Data System (ADS)

    Wallace, Ingvar Axel, II

    Half-collision studies of the quenching of excited states of Zn by Xe and Cd by H_2, CH_4 and i-C_4H _{10} have been undertaken and have provided information concerning the role of alignment of the excited metal atom p-orbital as well as other dynamical information and details about the potential energy surfaces (curves) involved in the quenching process. Van der Waals complexes of a single metal atom with a rare gas atom or quencher molecule are prepared using a supersonic expansion of the metal vapor, carrier gas and quencher gas. To provide a more detailed understanding of van der Waals bonding involving closed shell metal atoms, spectroscopic investigations of the MgcdotNe, Zncdot Ar and ZncdotKr C ^1Pi_1 and X^1 Sigma_0^+ states as well as the ZncdotXe D^1Sigma _0^+ and X^1Sigma _0^+ states via laser induced fluorescence have also been performed. No fluorescence is observed from the Zn cdotXe C^1Pi_1 state which predissociates to Zn(4s4p^3 P_{rm J}) + Xe, permitting the C state to be characterized via a Zn(4s4p^3P_2) "action spectrum." Modeling of the deeply bound C state and the shallow D state using Morse potentials suggests that the long range tail of the C state curve crosses the inner wall of the D state curve. For the CdcdotCH _4 and CdcdotC _4H_{10} complexes, fluorescence is not observed from either the C or D states. However, Cd(5s5p^3P _{rm J}) action spectra are obtained for C and D state excitation. A Cd(5s5p ^3P_0) action spectrum is observed as a result of CdcdotCH _4 A and B state excitation. Rotational structure is observed in the vibrational bands and has permitted characterization of the Cdcdot CH_4 X and A states within a pseudodiatomic approximation and provided evidence for hindered rotation of the methane molecule. When CdcdotH_2 or CdcdotD_2 is excited to the red of the Cd(5s5p^1 P_1 >=ts 5s5s^1S_0) atomic transition, fluorescence is again absent while Cd(5s5p ^3P_{rm J}) action spectra are observed. The observation in the spectra of

  16. Processing and characterization of nickel-carbon base metal matrix composites

    NASA Astrophysics Data System (ADS)

    Borkar, Tushar Murlidhar

    Carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) are attractive reinforcements for lightweight and high strength metal matrix composites due to their excellent mechanical and physical properties. The present work is an attempt towards investigating the effect of CNT and GNP reinforcements on the mechanical properties of nickel matrix composites. The CNT/Ni (dry milled) nanocomposites exhibiting a tensile yield strength of 350 MPa (about two times that of SPS processed monolithic nickel ˜ 160 MPa) and an elongation to failure ˜ 30%. In contrast, CNT/Ni (molecular level mixed) exhibited substantially higher tensile yield strength (˜ 690 MPa) but limited ductility with an elongation to failure ˜ 8%. The Ni- 1vol%GNP (dry milled) nanocomposite exhibited the best balance of properties in terms of strength and ductility. The enhancement in the tensile strength (i.e. 370 MPa) and substantial ductility (˜40%) of Ni-1vol%GNP nanocomposites was achieved due to the combined effects of grain refinement, homogeneous dispersion of GNPs in the nickel matrix, and well-bonded Ni- GNP interface, which effectively transfers stress across metal-GNP interface during tensile deformation. A second emphasis of this work was on the detailed 3D microstructural characterization of a new class of Ni-Ti-C based metal matrix composites, developed using the laser engineered net shaping (LENS(TM)) process. These composites consist of an in situ formed and homogeneously distributed titanium carbide (TiC) as well as graphite phase reinforcing the nickel matrix. 3D microstructure helps in determining true morphology and spatial distribution of TiC and graphite phase as well as the phase evolution sequence. These Ni-TiC-C composites exhibit excellent tribological properties (low COF), while maintaining a relatively high hardness.

  17. Processing of transition metal silicides for high-temperature applications

    SciTech Connect

    Deevi, S.C.; Sikka, V.K.

    1995-12-31

    The authors review and discuss recent developments in the processing and mechanical properties of MoSi{sub 2} and its composites. High-temperature creep rates of MoSi{sub 2} and its composites are compared to those of several intermetallics and discussed in relation to grain-size effects. Thermophysical properties of MoSi{sub 2} and Si{sub 3}N{sub 4} are compared, and the need for functionally graded composites of MoSi{sub 2}-Si{sub 3}N{sub 4} is discussed. This is followed by a discussion of combustion synthesis, reaction synthesis and densification, in-situ composite development, and reactive hot extrusion of metal-silicon mixtures. In combustion synthesis, a heterogeneous reaction occurs between liquid Si and Mo powder to form MoSi{sub 2}. This technique can be applied to obtain composites and alloys of MoSi{sub 2} and various other transition-metal silicides. In-situ synthesis of a composite of MoSi{sub 2}-Al{sub 2}O{sub 3} was carried out by reacting a thermite mixture consisting of MoO{sub 3}, Al, and Si powders. X-ray characterization of the products obtained at various temperatures reveals that the mechanism consists of a reduction of MoO{sub 3} by Al to MoO{sub 2}, followed by a simultaneous oxidation of Al to Al{sub 2}O{sub 3} and a synthesis reaction between reduced Mo and Si to form MoSi{sub 2}. The rate-determining step is found to be reduction of MoO{sub 2} by Al and oxidation of Al to Al{sub 2}O{sub 3}. The thermite reaction was moderated by adding Mo and Si to the mixture of MoO{sub 3}, Al, and Si, such that the ratio of MoSi{sub 2} to the thermite was in the range of 60:40 to 90:10. Reactive extrusion of metal-silicon mixtures of 3Ni-Si and Co-2Si results in a dense product with at least two phases.

  18. Emission behavior of sudan red 7B on dogbone-shaped gold nanorods: Aspect ratio dependence of the metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Rahman, Dewan S.; Sharma, Debdulal; Ghosh, Sujit Kumar

    2014-01-01

    Cetyltrimethylammonium bromide-stabilized 'dogbone-shaped' gold nanorods of aspect ratio varying from 1 to 6 have been synthesized by seed-mediated growth method in aqueous medium. Then, sudan red 7B, an alien molecular probe has been used as local probe to elucidate aspect ratio dependence of the nanorods on the photophysical properties of the dye molecules. It is seen that the relative intensity decreases exponentially with increasing aspect ratio and has been attributed to decrease in overall surface area for a particular concentration of the nanorods. The mechanism of fluorescence quenching has been ascribed to the electron and energy transfer processes in the gold-fluorophore hybrid nanostructures.

  19. Metallic photonic crystals based on solution-processible gold nanoparticles.

    PubMed

    Zhang, Xinping; Sun, Baoquan; Friend, Richard H; Guo, Hongcang; Nau, Dietmar; Giessen, Harald

    2006-04-01

    We demonstrate the fabrication of metallic photonic crystals, in the form of a periodic array of gold nanowires on a waveguide, by spin-coating a colloidal gold suspension onto a photoresist mask and subsequent annealing. The photoresist mask with a period below 500 nm is manufactured by interference lithography on an indium tin oxide (ITO) glass substrate, where the ITO layer has a thickness around 210 nm and acts as the waveguide. The width of the nanowires can be controlled from 100 to 300 nm by changing the duty cycle of the mask. During evaporation of solvent, the gold nanoparticles are drawn to the grooves of the grating with apparently complete dewetting off the photoresist for channels less than 2 microm in width, which therefore form nanowires after the annealing process. Strong coupling between the waveguide mode and the plasmon resonance of the nanowires, which is dependent on the polarization and incidence angle of the light wave, is demonstrated by optical extinction measurements. Continuity of the nanowires is confirmed by conductivity properties. Simplicity, high processing speed, and low cost are the main advantages of this method, which may have a plethora of applications in telecommunication, all-optical switching, sensors, and semiconductor devices.

  20. Biocompatible polyester macroligands: new subunits for the assembly of star-shaped polymers with luminescent and cleavable metal cores.

    PubMed

    Corbin, P S; Webb, M P; McAlvin, J E; Fraser, C L

    2001-01-01

    The synthesis of a series of star-shaped, biocompatible polyesters--polylactides (PLAs), polycaprolactones (PCLs), and various copolymer analogues--with either labile iron(II) tris-bipyridyl or luminescent ruthenium(II) tris-bipyridyl cores is described. These polymers were readily assembled by a convergent, metal-template-assisted approach that entailed the synthesis of bipyridine (bpy) ligands incorporating PLA- and PCL-containing arms and subsequent chelation of the "macroligands" to iron(II) or ruthenium(II). Specifically, the polyester macroligands bpyPLA(2) and bpyPCL(2) were prepared by a stannous octoate catalyzed ring-opening polymerization of DL- or L-lactide and epsilon-caprolactone, using bis(hydroxymethyl)-2,2'-bipyridine as the initiator. Copolymers bpy(PCL-PLA)(2) and bpy(PLA-PCL)(2) were generated in an analogous manner using bpyPLA(2) and bpyPCL(2) as macroinitiators. Polymers with narrow molecular weight distributions and with molecular weights close to values expected based upon monomer/initiator loading were produced. The macroligands were subsequently chelated to iron(II) to afford six-armed, iron-core star polymers, which were characterized by UV-vis and (1)H NMR spectroscopy. Estimated chelation efficiencies for formation of the star polymers (M(n) calcd: 20-240 kDa) were high, as determined by UV-vis spectral analysis. Within the molecular weight range investigated, differential scanning calorimetry and thermogravimetric analysis revealed that the small amounts of metal in the polyester stars and differences in polymer architecture had little effect on the thermal properties of the PLA/PCL materials. However, thin films of the red-violet colored iron-core stars exhibited reversible, thermochromic bleaching. Solutions and films of the polymers also responded (with color loss) to a variety of chemical stimuli (e.g., acid, base, peroxides, ammonia), thus revealing potential for use in diverse sensing applications. Likewise, the polyester

  1. Metallic nanoparticle shape and size effects on aluminum oxide-induced enhancement of exciton-plasmon coupling and quantum dot emission

    SciTech Connect

    Wing, Waylin J.; Sadeghi, Seyed M. Gutha, Rithvik R.; Campbell, Quinn; Mao, Chuanbin

    2015-09-28

    We investigate the shape and size effects of gold metallic nanoparticles on the enhancement of exciton-plasmon coupling and emission of semiconductor quantum dots induced via the simultaneous impact of metal-oxide and plasmonic effects. This enhancement occurs when metallic nanoparticle arrays are separated from the quantum dots by a layered thin film consisting of a high index dielectric material (silicon) and aluminum oxide. Our results show that adding the aluminum oxide layer can increase the degree of polarization of quantum dot emission induced by metallic nanorods by nearly two times, when these nanorods have large aspect ratios. We show when the aspect ratio of these nanorods is reduced to half, the aluminum oxide loses its impact, leading to no improvement in the degree of polarization. These results suggest that a silicon/aluminum oxide layer can significantly enhance exciton-plasmon coupling when quantum dots are in the vicinity of metallic nanoantennas with high aspect ratios.

  2. The Potato Chip Really Does Look Like Elvis! Neural Hallmarks of Conceptual Processing Associated with Finding Novel Shapes Subjectively Meaningful

    PubMed Central

    Federmeier, Kara D.; Paller, Ken A.

    2012-01-01

    Clouds and inkblots often compellingly resemble something else—faces, animals, or other identifiable objects. Here, we investigated illusions of meaning produced by novel visual shapes. Individuals found some shapes meaningful and others meaningless, with considerable variability among individuals in these subjective categorizations. Repetition for shapes endorsed as meaningful produced conceptual priming in a priming test along with concurrent activity reductions in cortical regions associated with conceptual processing of real objects. Subjectively meaningless shapes elicited robust activity in the same brain areas, but activity was not influenced by repetition. Thus, all shapes were conceptually evaluated, but stable conceptual representations supported neural priming for meaningful shapes only. During a recognition memory test, performance was associated with increased frontoparietal activity, regardless of meaningfulness. In contrast, neural conceptual priming effects for meaningful shapes occurred during both priming and recognition testing. These different patterns of brain activation as a function of stimulus repetition, type of memory test, and subjective meaningfulness underscore the distinctive neural bases of conceptual fluency versus episodic memory retrieval. Finding meaning in ambiguous stimuli appears to depend on conceptual evaluation and cortical processing events similar to those typically observed for known objects. To the brain, the vaguely Elvis-like potato chip truly can provide a substitute for the King himself. PMID:22079921

  3. The potato chip really does look like Elvis! Neural hallmarks of conceptual processing associated with finding novel shapes subjectively meaningful.

    PubMed

    Voss, Joel L; Federmeier, Kara D; Paller, Ken A

    2012-10-01

    Clouds and inkblots often compellingly resemble something else--faces, animals, or other identifiable objects. Here, we investigated illusions of meaning produced by novel visual shapes. Individuals found some shapes meaningful and others meaningless, with considerable variability among individuals in these subjective categorizations. Repetition for shapes endorsed as meaningful produced conceptual priming in a priming test along with concurrent activity reductions in cortical regions associated with conceptual processing of real objects. Subjectively meaningless shapes elicited robust activity in the same brain areas, but activity was not influenced by repetition. Thus, all shapes were conceptually evaluated, but stable conceptual representations supported neural priming for meaningful shapes only. During a recognition memory test, performance was associated with increased frontoparietal activity, regardless of meaningfulness. In contrast, neural conceptual priming effects for meaningful shapes occurred during both priming and recognition testing. These different patterns of brain activation as a function of stimulus repetition, type of memory test, and subjective meaningfulness underscore the distinctive neural bases of conceptual fluency versus episodic memory retrieval. Finding meaning in ambiguous stimuli appears to depend on conceptual evaluation and cortical processing events similar to those typically observed for known objects. To the brain, the vaguely Elvis-like potato chip truly can provide a substitute for the King himself.

  4. Process for recovering tritium from molten lithium metal

    DOEpatents

    Maroni, Victor A.

    1976-01-01

    Lithium tritide (LiT) is extracted from molten lithium metal that has been exposed to neutron irradiation for breeding tritium within a thermonuclear or fission reactor. The extraction is performed by intimately contacting the molten lithium metal with a molten lithium salt, for instance, lithium chloride - potassium chloride eutectic to distribute LiT between the salt and metal phases. The extracted tritium is recovered in gaseous form from the molten salt phase by a subsequent electrolytic or oxidation step.

  5. Emergence of tissue mechanics from cellular processes: shaping a fly wing

    NASA Astrophysics Data System (ADS)

    Merkel, Matthias; Etournay, Raphael; Popovic, Marko; Nandi, Amitabha; Brandl, Holger; Salbreux, Guillaume; Eaton, Suzanne; Jülicher, Frank

    Nowadays, biologistsare able to image biological tissueswith up to 10,000 cells in vivowhere the behavior of each individual cell can be followed in detail.However, how precisely large-scale tissue deformation and stresses emerge from cellular behavior remains elusive. Here, we study this question in the developing wing of the fruit fly. To this end, we first establish a geometrical framework that exactly decomposes tissue deformation into contributions by different kinds of cellular processes. These processes comprise cell shape changes, cell neighbor exchanges, cell divisions, and cell extrusions. As the key idea, we introduce a tiling of the cellular network into triangles. This approach also reveals that tissue deformation can also be created by correlated cellular motion. Based on quantifications using these concepts, we developed a novel continuum mechanical model for the fly wing. In particular, our model includes active anisotropic stresses and a delay in the response of cell rearrangements to material stresses. A different approach to study the emergence of tissue mechanics from cellular behavior are cell-based models. We characterize the properties of a cell-based model for 3D tissues that is a hybrid between single particle models and the so-called vertex models.

  6. Interpersonal politics: the role of terror management and attachment processes in shaping political preferences.

    PubMed

    Weise, David R; Pyszczynski, Tom; Cox, Cathy R; Arndt, Jamie; Greenberg, Jeff; Solomon, Sheldon; Kosloff, Spee

    2008-05-01

    Research on terror management theory (TMT) indicates that reminders of death affect political attitudes, but political orientation only sometimes moderates these effects. We propose that secure relationships are associated with values of tolerance and compassion, thus orienting people toward liberalism; insecure attachments are associated with more rigid and absolutist values that orient people toward conservatism. Given that attachment relationships become especially active when security needs are heightened, we predicted that mortality salience would be an important factor in understanding the relationship between attachment processes and political orientation. Supporting these ideas, Study 1 showed that after a mortality-salience manipulation, securely attached participants increased their support for a liberal presidential candidate, and less securely attached participants increased their support for a conservative presidential candidate. In Study 2, a secure-relationship prime following a mortality-salience manipulation engendered a less violent approach to the problem of terrorism than did a neutral-relationship prime. We discuss the interaction of TMT processes and individual differences in attachment in shaping political preferences.

  7. Characterization Of An EBL System: The Influence Of Process Parameters On Thickness Resist And Engraving Shapes

    SciTech Connect

    D'Urso, G.; Longo, M.; Ravasio, C.; Maccarini, G.

    2011-01-17

    In LIGA process, the low flexibility due to the use of masks might be overcome using the electron beam of a scansion electron microscope (SEM) instead of the synchrotron radiation. In this way, through the vector control of the beam, it is possible to irradiate a specific path on the resist without using any mask. Anyway, it is important to remark that the Electron Beam Lithography (EBL) can not include all the applications of the X-ray LIGA technique but it could be a valid alternative only for some specific uses. In particular, some limits concerning the impression of high thickness resists are expected. An EBL system based on a SEM was recently implemented by the authors and some tests were carried out to characterize the device performances. Aim of this work is to asses the system performances in terms of maximum impressible thickness resist and shape of the engraved entities. Several tests were carried out by varying the resist thickness and the process parameters.

  8. Holocene hillslope processes and deposits in two U-shaped mountain valleys in western Norway

    NASA Astrophysics Data System (ADS)

    Laute, K.; Beylich, A. A.

    2012-04-01

    This doctoral research project is integrated in the Norwegian Research Council (NFR) funded SedyMONT-Norway Project within the ESF EUROCORES TOPO-EUROPE SedyMONT (Timescales of sediment dynamics, climate and topographic change in mountain landscapes) Programme. Research is carried out within two steep, U-shaped and glacier-connected tributary valleys (Erdalen and Bødalen) on the western side of the Jostedalsbreen ice cap in western Norway. Contemporary denudative processes in both valley systems include rock and boulder falls, avalanches, slush flows, debris flows, creep processes, wash- and chemical denudation and fluvial transport of solutes, suspended sediments and bedload. The main aims of this research project which are approached within a Holocene to contemporary timescale are: (i) to investigate the spatio-temporal variability of Holocene hillslope development, (ii) to analyse more specificly the morphometric influences and geomorphic consequences of the Little Ice Age (LIA) glacier advance on selected hillslope systems within defined headwater areas in both valleys, (iii) to study morphometric and meteorological controls of contemporary denudative slope processes as well as (iv) to quantify the rates of sediment delivery from headwater areas and its changes over time. A process-based approach is applied using a variety of different methods and techniques. Focus is on different temporal (Holocene to contemporary) and spatial (selected hillslope systems, headwater areas and entire valley system) scales. The applied methods include orthophoto- and topographical map interpretation, GIS and DEM computing, geomorphological fieldmapping and hillslope profile surveying complemented by relative dating techniques (lichenometry and dendrochronology), geophysical investigations and terrestrial laser scanning (LIDAR). For monitoring contemporary rates of slope processes a designed monitoring programme (running since 2009) with a wide spectrum of instrumentation; e

  9. Microstructural Evolution and Functional Properties of Fe-Mn-Al-Ni Shape Memory Alloy Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Niendorf, Thomas; Brenne, Florian; Krooß, Philipp; Vollmer, Malte; Günther, Johannes; Schwarze, Dieter; Biermann, Horst

    2016-06-01

    In the current study, a Fe-Mn-Al-Ni shape memory alloy is processed by additive manufacturing for the first time. Microstructural evolution upon processing is strongly affected by thermal gradients and solidification velocity and, thus, by processing parameters and the actual specimen geometry. By single-step solutionizing heat treatment pronounced grain growth is initiated leading to microstructures showing good reversibility. The compressive stress-strain response revealed maximum reversible pseudo-elastic strain of about 7.5 pct. Critical steps toward further optimization of additively manufactured Fe-Mn-Al-Ni shape memory alloys are discussed.

  10. Characteristics Of Basaltic Sand: Size, Shape, And Composition As A Function Of Transport Process And Distance

    NASA Astrophysics Data System (ADS)

    Craddock, R. A.; Needell, Z. A.; Rose, T. R.

    2012-04-01

    Overview: The chemical and physical characteristics of sedimentary material can provide valuable clues about transport processes, distance traveled, and provenance, all of which are aspects of Martian geography that we would like to better understand. For a typical sedimentary deposit on Earth, for example, it has been shown that the ratio of feldspar to quartz can be used to assess the maturity (or transport distance) of a terrestrial deposit, because feldspar is more vulnerable to weathering than quartz. Further, chemical analysis can also be used to determine potential sediment sources, and grain-size sorting can be used to distinguish aeolian sediments (typically well-sorted) from fluvial sediments (poorly sorted in high energy environments). It is also common to use the shapes of individual quartz particles to determine transport process and distance, all of which can help us better understand the history of a sample of sedimentary material and the geological processes that created and emplaced it. These traditional sedimentological concepts are now being applied to our interpretation of Martian surface materials. Sullivan et al. [2008], for example, used grain-size and shape to assess eolian processes and to qualify transport distances of deposits found at the Spirit landing site in Gusev Crater. Stockstill-Cahill et al. [62008 used variations in mineral abundances observed in multispectral data to determine the provenance of dark dunes found in Amazonis Planitia craters. While applying our understanding of terrestrial sedimentary materials to Martian surface materials is intuitively sound and logical, the problem is that most of our current understanding is based on sediments derived from felsic materials (e.g., granite) primarily because that is the composition of most of the landmass on the Earth. However, the Martian surface is composed primarily of mafic material, or basalt, which generates much different sedimentary particles as it weathers. Instead of

  11. Lower Restrictions for Sheet Metal Trimming Processes can Reduce Die Costs in The Automotive Industry

    NASA Astrophysics Data System (ADS)

    Hogg, Markus; Rohleder, Martin; Roll, Karl

    2011-05-01

    To reduce costs of trimming dies influencing parameters of the shearing process were identified, new technical approaches for a more cost efficient die design were developed, and comprehensive investigations on a sample tool were done. These approaches will be verified on a trimming die in series production. If this pilot application is successful, many sheet metal forming parts can be trimmed by less die investment in the future. In the automotive industry complex sheet metal forming parts are often trimmed by shearing. Ideally this shearing is done with a 90° angle between the cutting edge and the part surface. Because of complex part geometry different angles always occur. Often shearing angles and the effective sheet thickness increases so much that trimming in the working direction of the press machine is not possible anymore. In these cases sliding cams have to be used. That makes trimming dies expensive and maintenance intensive. For reliable trimming a good understanding of the process and its limitations is necessary. By not considering these limitations the tool can fail after a few operations or/and the resulting edge of the sheet metal part is no longer acceptable. In worst case a new tool has to be built or at least must be reworked. In operational practice so far only empirical values about limitations are known. The stability limit for trimming is not known for all shearing angles and for new high-strength materials. Therefore detailed investigations were done on a sample tool to determine these stability limits for different materials and shearing angles. The basis for starting these principle investigations was empirical values from operational practise. By using a high-quality material and a completely new shape for the trimming die elements both the reliable processable effective sheet thickness respectively the shearing angle as well as the acting forces could be optimized. In the basic investigations trimming in one direction was often still

  12. Titanium Metal Powder Production by the Plasma Quench Process

    SciTech Connect

    R. A. Cordes; A. Donaldson

    2000-09-01

    The goals of this project included the scale-up of the titanium hydride production process to a production rate of 50 kg/hr at a purity level of 99+%. This goal was to be achieved by incrementally increasing the production capability of a series of reactor systems. This methodic approach was designed to allow Idaho Titanium Technologies to systematically address the engineering issues associated with plasma system performance, and powder collection system design and performance. With quality powder available, actual fabrication with the titanium hydride was to be pursued. Finally, with a successful titanium production system in place, the production of titanium aluminide was to be pursued by the simultaneously injection of titanium and aluminum precursors into the reactor system. Some significant accomplishments of the project are: A unique and revolutionary torch/reactor capable of withstanding temperatures up to 5000 C with high thermal efficiency has been operated. The dissociation of titanium tetrachloride into titanium powder and HC1 has been demonstrated, and a one-megawatt reactor potentially capable of producing 100 pounds per hour has been built, but not yet operated at the powder level. The removal of residual subchlorides and adsorbed HC1 and the sintering of powder to form solid bodies have been demonstrated. The production system has been operated at production rates up to 40 pounds per hour. Subsequent to the end of the project, Idaho Titanium Technologies demonstrated that titanium hydride powder can indeed be sintered into solid titanium metal at 1500 C without sintering aids.

  13. Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

    PubMed Central

    El-Safty, Sherif A.; Shenashen, Mohamed A.; Sakai, Masaru; Elshehy, Emad; Halada, Kohmei

    2015-01-01

    Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobaltmetals. PMID:26709467

  14. Component processes in contour integration: a direct comparison between snakes and ladders in a detection and a shape discrimination task.

    PubMed

    Vancleef, Kathleen; Wagemans, Johan

    2013-11-01

    In contour integration, a relevant question is whether snakes and ladders are processed similarly. Higher presentation time thresholds for ladders in detection tasks indicate this is not the case. However, in a detection task only processing differences at the level of element linking and possibly contour localization might be picked up, while differences at the shape encoding level cannot be noticed. In this study, we make a direct comparison of detection and shape discrimination tasks to investigate if processing differences in the visual system between snakes and ladders are limited to contour detection or extend to higher level contour processing, like shape encoding. Stimuli consisted of elements that were oriented collinearly (snakes) or orthogonally (ladders) to the contour path and were surrounded by randomly oriented background elements. In two tasks, six experienced subjects either detected the contour when presented with a contour and a completely random stimulus or performed a shape discrimination task when presented with two contours with different curvature. Presentation time was varied in 9 steps between 8 and 492 ms. By applying a generalized linear mixed model we found that differences in snake and ladder processing are not limited to a detection stage but are also apparent at a shape encoding stage.

  15. Understanding Metallic Bonding: Structure, Process and Interaction by Rasch Analysis

    ERIC Educational Resources Information Center

    Cheng, Maurice M. W.; Oon, Pey-Tee

    2016-01-01

    This paper reports the results of a survey of 3006 Year 10-12 students on their understandings of metallic bonding. The instrument was developed based on Chi's ontological categories of scientific concepts and students' understanding of metallic bonding as reported in the literature. The instrument has two parts. Part one probed into students'…

  16. Process for continuous production of metallic uranium and uranium alloys

    DOEpatents

    Hayden, Jr., Howard W.; Horton, James A.; Elliott, Guy R. B.

    1995-01-01

    A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO.sub.3), or any other substantially stable uranium oxide, to form the uranium dioxide (UO.sub.2). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl.sub.4), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation.

  17. Process for continuous production of metallic uranium and uranium alloys

    DOEpatents

    Hayden, H.W. Jr.; Horton, J.A.; Elliott, G.R.B.

    1995-06-06

    A method is described for forming metallic uranium, or a uranium alloy, from uranium oxide in a manner which substantially eliminates the formation of uranium-containing wastes. A source of uranium dioxide is first provided, for example, by reducing uranium trioxide (UO{sub 3}), or any other substantially stable uranium oxide, to form the uranium dioxide (UO{sub 2}). This uranium dioxide is then chlorinated to form uranium tetrachloride (UCl{sub 4}), and the uranium tetrachloride is then reduced to metallic uranium by reacting the uranium chloride with a metal which will form the chloride of the metal. This last step may be carried out in the presence of another metal capable of forming one or more alloys with metallic uranium to thereby lower the melting point of the reduced uranium product. The metal chloride formed during the uranium tetrachloride reduction step may then be reduced in an electrolysis cell to recover and recycle the metal back to the uranium tetrachloride reduction operation and the chlorine gas back to the uranium dioxide chlorination operation. 4 figs.

  18. Landslide-induced iron mobilisation shapes benthic accumulation of nutrients, trace metals and REE fractionation in an oligotrophic alpine stream

    NASA Astrophysics Data System (ADS)

    Johnston, Scott G.; Rose, Andrew L.; Burton, Edward D.; Webster-Brown, Jenny

    2015-01-01

    .01). P K-edge XANES indicates P is associated with both ferric and Ca-phosphate minerals, while SEM-EDX elemental mapping of Fe(III) precipitates reveal strong spatial associations between P, Ca and Fe. Cobble Fe(III)-rich biofilm is also sorbing and accumulating multiple trace metals and REE. Within the landslide zone there are significant (P < 0.01) enrichments (up to ∼10-100 times background) for most trace metals examined here and metals display significant positive linear correlations with Fe(III)Ab on a log transformed basis. Stream cobble biofilm also exhibits distinct REE fractionation along the flow path, with light REE (La, Ce, Nd, Pr) preferentially partitioning to the Fe(III) and Mn-rich biofilm within the landslide zone. Accumulation of PO43- and trace metals in this relatively environmentally labile form may have implications for their bioavailability and downstream transport, but further research is required to assess possible ecological consequences. This study demonstrates the potential for large alpine landslides to encourage reach-scale circumneutral Fe mobilisation in adjacent streams, thereby shaping multiple aspects of benthic stream geochemistry for many years after the landslide event itself.

  19. Development of Replacements for Phoscoating Used in Forging, Extrusion and Metal Forming Processes

    SciTech Connect

    Kerry Barnett

    2003-03-01

    Many forging, extrusion, heading and other metal forming processes use graphite-based lubricants, phosphate coatings, and other potentially hazardous or harmful substances to improve the tribology of the metal forming process. The application of phosphate-based coatings has long been studied to determine if other synthetic ''clean'' lubricants could provide the same degree of protection afforded by phoscoatings and its formulations. So far, none meets the cost and performance objectives provided by phoscoatings as a general aid to the metal forming industry. In as much as phoscoatings and graphite have replaced lead-based lubricants, the metal forming industry has had previous experience with a legislated requirement to change processes. However, without a proactive approach to phoscoating replacement, many metal forming processes could find themselves without a cost effective tribology material necessary for the metal forming process

  20. Effects of shielding coatings on the anode shaping process during counter-rotating electrochemical machining

    NASA Astrophysics Data System (ADS)

    Wang, Dengyong; Zhu, Zengwei; Wang, Ningfeng; Zhu, Di

    2016-06-01

    Electrochemical machining (ECM) has been widely used in the aerospace, automotive, defense and medical industries for its many advantages over traditional machining methods. However, the machining accuracy in ECM is to a great extent limited by the stray corrosion of the unwanted material removal. Many attempts have been made to improve the ECM accuracy, such as the use of a pulse power, passivating electrolytes and auxiliary electrodes. However, they are sometimes insufficient for the reduction of the stray removal and have their limitations in many cases. To solve the stray corrosion problem in CRECM, insulating and conductive coatings are respectively used. The different implement processes of the two kinds of coatings are introduced. The effects of the two kinds of shielding coatings on the anode shaping process are investigated. Numerical simulations and experiments are conducted for the comparison of the two coatings. The simulation and experimental results show that both the two kinds of coatings are valid for the reduction of stray corrosion on the top surface of the convex structure. However, for insulating coating, the convex sidewall becomes concave when the height of the convex structure is over 1.26 mm. In addition, it is easy to peel off by the high-speed electrolyte. In contrast, the conductive coating has a strong adhesion, and can be well reserved during the whole machining process. The convex structure fabricated by using a conductive iron coating layer presents a favorable sidewall profile. It is concluded that the conductive coating is more effective for the improvement of the machining quality in CRECM. The proposed shielding coatings can also be employed to reduce the stray corrosion in other schemes of ECM.