Sample records for nanostructured composite materials

  1. Fused silica as a composite nanostructured material

    Microsoft Academic Search

    V. K. Miloslavsky; E. D. Makovetsky; L. A. Ageev; K. S. Beloshenko

    2009-01-01

    A method for calculating the refractive index of optical fused silica by applying the model of effective permittivity of composite\\u000a homogeneous media is proposed and realized. The calculation was performed using the tabular data of the refractive index of\\u000a crystalline ? quartz and the ratio of the quartz glass and ? quartz densities. It was suggested that fused silica contains

  2. Thermochemical synthesis and characterization of nanostructured chromium suicide and silicon carbide composite materials

    Microsoft Academic Search

    P. Luo; P. R. Strutt

    1995-01-01

    Nanostructured chromium suicide\\/silicon carbide in the form of composite powders have been synthesized from water-soluble precursors by a spray-dry and thermal conversion process. Two materials compositions were investigated to provide insight into the relation between the initial precursor composition and the composition of the synthesized nanostructured materials. The multiphase materials that were produced contain (i) cubic ß-SiC and hexagonal Cr5-xSi3-yCx+y(Cr5Si3Cx).

  3. Composite nano-structured calcium silicate phase change materials for thermal buffering in food packaging

    Microsoft Academic Search

    James H. Johnston; James E. Grindrod; Margaret Dodds; Katrin Schimitschek

    2008-01-01

    A new nano-structured calcium silicate (NCS) – phase change composite material has been developed to provide effective thermal buffering for paperboard packages during the transport and temporary storage of chilled perishable food from the supplier to the market. NCS is a proprietary material comprising nano-size platelets stacked together in a unique open framework structure having a high pore volume and

  4. Fabrication of a nanostructured gold-polymer composite material

    NASA Astrophysics Data System (ADS)

    Mallick, K.; Witcomb, M.; Scurrell, M.

    2006-07-01

    A facile synthesis route is described for the preparation of a poly-(o-aminophenol)-gold nanoparticle composite material by polymerization of o-aminophenol (AP) monomer using HAuCl4 as the oxidant. The synthesis was carried out in a methanol medium so that it could serve a dual solvent role, a solvent for both the AP and the water solution of HAuCl4. It was found that oxidative polymerization of AP leads to the formation of poly-AP with a diameter of 50±10nm, while the reduction of AuCl4- results in the formation of gold nanoparticles (˜ 2nm). The gold nanoparticles were uniformly dispersed and highly stabilized throughout the macromolecular chain that formed a uniform metal-polymer composite material. The resultant composite material was characterized by means of different techniques, such as UV-vis, IR and Raman spectroscopy, which offered the information about the chemical structure of polymer, whereas electron microscopy images provided information regarding the morphology of the composite material and the distribution of the metal particles in the composite material.

  5. Structure and properties of nano-structural composite material CU0.56 R% ZrO\\/sub 2

    Microsoft Academic Search

    B. Skosyrskii; A. N. Tabachenko

    2003-01-01

    Advances in the methods for studying the plastic deformation in volumetric nanostructural materials have been made in recent years. With the usage of the particles tolerance of strengthening phase with low dissolution in matrix and high particles tolerance to the coagulation processes, one can expect that nano-structural composite material can have not only high strength but also high stability of

  6. Optical and electrical properties of composite nanostructured materials

    NASA Astrophysics Data System (ADS)

    Amooali Khosroabadi, Akram

    A novel lithographic fabrication method is used to fabricate nanopillars arrays of anisotropic Ag and TCO electrodes. Optical and electrical properties of the electrodes including bandgap, free carrier concentration, resistivity and surface plasmon frequency of different electrodes can be tuned by adjusting the dimensions and geometry of the pillars. Given the ability to tune the nonlocal responses of the plasmonic field enhancements, we attempt to determine the nature of the effective refractive index profile within the visible wavelength region for multi-layer hybrid nanostructures. Knowledge of the effective optical constants of the obtained structure is critical for various applications. nanopillars of TCOAg core shell structures have been successfully fabricated. The Maxwell-Garnett mixing law has been used to determine the optical constants of the nanostructure based on spectroscopic ellipsometry measurements. Simulated reflection spectra indicate a down shift in the Brewster angle of the pillars resulting from the reduction in the effective refractive index of the nanostructure. Two plasmonic resonances were observed, with one in the visible region and the other in the IR region. Plasmon hybridization model is used to describe the behavior of metal and metal oxide core shell nanostructured electrodes. Different charge density distributions around the pillars determine the plasma frequency which depends on the core and surrounding media dielectric constants. Finite Difference Time Domain (FDTD) simulation of different structures agree well with experiment and help us to understand electric field behavior at different structures with different geometries and dielectric constants. Plasmonic Ag nanopillar arrays are effective substrates for surface enhanced Raman spectroscopy (SERS). An enhancement factor up to 6 orders of magnitude is obtained. Monolayers of C60 is deposited on the Ag nanopillars and the interface of C60/Ag is studied which is important in optoelectronic devices. Electron delocalization between C60 and Ag is confirmed.

  7. Three dimensional, bulk nanostructured materials and composites have matured into a new class of materials that is being considered in a variety of engineering applications. The successful synthesis of large-scale nanostructured materials is of

    E-print Network

    Three dimensional, bulk nanostructured materials and composites have matured into a new class has recently been extended into the realm of metal composites with tri-modal microstructural and His M.S. in Metallurgy and Ph.D. in Material Engineering broth the Massachusetts Institute

  8. The process of nanostructuring of metal (iron) matrix in composite materials for directional control of the mechanical properties.

    PubMed

    Zemtsova, Elena; Yurchuk, Denis; Smirnov, Vladimir

    2014-01-01

    We justified theoretical and experimental bases of synthesis of new class of highly nanostructured composite nanomaterials based on metal matrix with titanium carbide nanowires as dispersed phase. A new combined method for obtaining of metal iron-based composite materials comprising the powder metallurgy processes and the surface design of the dispersed phase is considered. The following stages of material synthesis are investigated: (1) preparation of porous metal matrix; (2) surface structuring of the porous metal matrix by TiC nanowires; (3) pressing and sintering to give solid metal composite nanostructured materials based on iron with TiC nanostructures with size 1-50 nm. This material can be represented as the material type "frame in the frame" that represents iron metal frame reinforcing the frame of different chemical compositions based on TiC. Study of material functional properties showed that the mechanical properties of composite materials based on iron with TiC dispersed phase despite the presence of residual porosity are comparable to the properties of the best grades of steel containing expensive dopants and obtained by molding. This will solve the problem of developing a new generation of nanostructured metal (iron-based) materials with improved mechanical properties for the different areas of technology. PMID:24695459

  9. Nanostructured LiMPO4 (M = Fe, Mn, Co, Ni) - carbon composites as cathode materials for Li-ion battery

    NASA Astrophysics Data System (ADS)

    Dimesso, L.; Spanheimer, C.; Nguyen, T. T. D.; Hausbrand, R.; Jaegermann, W.

    2012-10-01

    Nanostructured materials are considered to be strong candidates for fundamental advances in efficient storage and/or conversion. In nanostructured materials transport kinetics and surface processes play determining roles. This work describes recent developments in the synthesis and characterization of composites which consist of lithium metal phosphates (LiMPO4, M = Fe, Mn, Co, Ni) coated on nanostructured carbon supports (unordered nanofibers, foams). The composites have been prepared by coating the carbon structures in aqueous (or polyols) solutions containing lithium, metal ions and phosphates. After drying out, the composites have been thermally treated at different temperatures (between 600-780°C) for 5-12 hours under nitrogen. The formation of the olivine structured phase was confirmed by the X-ray diffraction analysis on powders prepared under very similar conditions. The surface investigation revealed the formation of an homogeneous coating of the olivine phase on the carbon structures. The electrochemical performance on the composites showed a dramatic improvement of the discharge specific capacity (measured at a discharge rate of C/25 and room temperature) compared to the prepared powders. The delivered values were 105 mAhg-1 for M = Fe, 100 mAhg-1 for M = Co, 70 mAhg-1 for M = Mn and 30 mAhg-1 for M = Ni respectively.

  10. Characterization of nanostructured PbO2–PANi composite materials synthesized by combining electrochemical and chemical methods

    NASA Astrophysics Data System (ADS)

    Binh Phan, Thi; Tot Pham, Thi; Thanh Thuy Mai, Thi

    2013-03-01

    Nanostructured PbO2–PANi composite materials were prepared by combining electrochemical and chemical methods. Firstly, PbO2 was deposited on a stainless steel substrate by pulsed current method and then obtained PbO2 electrode was immersed into acidic aniline solution to form nanostructured PbO2–PANi composites. The synthesized samples were characterized by infrared (IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD). The electrocatalytic oxidation of methanol on those composites was evaluated by potentiodynamic polarization from 1.4 to 2.2 V versus Ag/AgCl/saturated KCl electrode. The adsorption of N–H group as well as the presence of benzoid and quinoid ring vibrations on IR-spectrum asserts that PANi coexisted with ?-PbO2 which is evidenced by x-ray analysis. With increasing immersion times of the PbO2 electrode in the acidic aniline solution the electrocatalytic performance of the obtained PbO2–PANi composites for methanol oxidation was improved due to the formation of less closely knitted nano-sized PANi fibers, which was confirmed by surface morphology analysis.

  11. Nanostructured, electroactive and bioapplicable materials

    NASA Astrophysics Data System (ADS)

    Cheng, Shan

    Novel nanostructured porous sol-gel materials, nanocomposites, electroactive and bioapplicable materials have been successfully developed for a wide range of perceivable applications. Several versatile nonsurfactant templated sol-gel pathways have been developed to prepare nanostructured porous materials and composites with different morphologies (e.g., monoliths, nanospheres, nanoparticles, and thin films), structures, compositions and properties. The synthetic conditions were systematically studied and optimized. The template effects on pore structure as well as synthetic process, especially template removal steps, have been investigated. The composition and pore structures were thoroughly studied with various spectroscopic and microscopic methods such as IR, TGA, SEM, TEM, BET and XRD. The obtained mesoporous materials usually exhibit high surface area, large pore volume and narrowly distributed pore diameter. The porosity can be fine tuned simply by adjusting the template concentration. The convenient synthesis as well as the distinctive structure and physical-chemical properties render these sol-gel materials great suitability for a wide range of potential applications, such as chemical and biological sensors, catalysts, drug delivery and functional coatings. Biocompatible and electroactive nanocomposites have been prepared through a biological agent (i.e., collagen) templated chemical polymerization of aniline monomers. The resultant polyaniline-collagen complexes exhibit well controlled doping-dedoping electroactivity and much enhanced solubility. Demonstrated with cell growth studies, the polyaniline-collagen complexes show improved biocompatibility in comparison to polyaniline. The new materials can be used to fabricate scaffolds, with which the effect of electrical stimuli on cell growth and differentiation can be evaluated with the hope of ultimately using electrical signal to stimulate controllable cell and tissue regeneration. Aniline derivative substituted quinoline ligand compounds and their complexes have been prepared and investigated as potential electroluminescent materials.

  12. Nanostructured Materials for Solar Cells

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila; Raffaelle, Ryne; Castro, Stephanie; Fahey, S.; Gennett, T.; Tin, P.

    2003-01-01

    The use of both inorganic and organic nanostructured materials in producing high efficiency photovoltaics is discussed in this paper. Recent theoretical results indicate that dramatic improvements in device efficiency may be attainable through the use of semiconductor quantum dots in an ordinary p-i-n solar cell. In addition, it has also recently been demonstrated that quantum dots can also be used to improve conversion efficiencies in polymeric thin film solar cells. A similar improvement in these types of cells has also been observed by employing single wall carbon nanotubes. This relatively new carbon allotrope may assist both in the disassociation of excitons as well as carrier transport through the composite material. This paper reviews the efforts that are currently underway to produce and characterize these nanoscale materials and to exploit their unique properties.

  13. Hierarchically Nanostructured Materials for Sustainable Environmental Applications

    NASA Astrophysics Data System (ADS)

    Ren, Zheng; Guo, Yanbing; Liu, Cai-Hong; Gao, Pu-Xian

    2013-11-01

    This article presents a comprehensive overview of the hierarchical nanostructured materials with either geometry or composition complexity in environmental applications. The hierarchical nanostructures offer advantages of high surface area, synergistic interactions and multiple functionalities towards water remediation, environmental gas sensing and monitoring as well as catalytic gas treatment. Recent advances in synthetic strategies for various hierarchical morphologies such as hollow spheres and urchin-shaped architectures have been reviewed. In addition to the chemical synthesis, the physical mechanisms associated with the materials design and device fabrication have been discussed for each specific application. The development and application of hierarchical complex perovskite oxide nanostructures have also been introduced in photocatalytic water remediation, gas sensing and catalytic converter. Hierarchical nanostructures will open up many possibilities for materials design and device fabrication in environmental chemistry and technology.

  14. Nanostructure Titania Reinforced Conducting Polymer Composites

    NASA Astrophysics Data System (ADS)

    Kondawar, S. B.; Thakare, S. R.; Khati, V.; Bompilwar, S.

    Composites of polyaniline with synthesized nanostructured titania (TiO2) and polyaniline with commercial TiO2 have been in situ synthesized by oxidative chemical polymerization method. Sulfuric acid was used as dopant during the polymerization process. Sol-gel precipitates of nanostructured titania were synthesized by hydrolyzing the mixture of titanium chloride (TiCl3) and colloidal transparent solution of starch. Composite materials were subjected for comparison to spectroscopic and X-ray diffraction analysis. Strong coupling/interaction of titania with the imine nitrogen in polyaniline confirmed by FTIR spectral analysis. XRD shows the composite of synthesized titania with polyaniline have broaden peak as compared to that of commercial titania with polyaniline indicating particle size in the range of nanometer scale which is supported by 40 nm particle size of the synthesized titania from TEM picture. Increase in conductivity with increasing temperature was observed in both the composite materials.

  15. Laser-induced deposition of nanostructured copper microwires on surfaces of composite materials

    NASA Astrophysics Data System (ADS)

    Tumkin, Ilia I.; Panov, Maxim S.; Shishkova, Ekaterina V.; Bal'makov, Michail D.

    2015-05-01

    Microelectronics industry is growing fast and the rate of new devices' development increases every year. Therefore, methods for simple and high-precision metal coating on dielectrics are needed. Existing methods do not allow performing the high-precision metal deposition without using photomasks, while making photomask for each prototype is long and expensive process. One of the methods of maskless metal deposition is laser-induced chemical liquid-phase deposition (LCLD). In this work we show the effect of substrate surface type on a result of LCLD. Deposited copper structures were characterized by SEM, EDX and impedance spectroscopy. The results show that laser-induced copper deposition is highly affected by the surface being homogeneous or composite material. It was found that the deposits with low resistivity and high quality metal localization mostly appear on the two-phase surfaces. In contrast, deposits on one-phase surfaces exhibited poor topology of copper material.

  16. A Study of Nanostructured Cu-Ag Composites

    Microsoft Academic Search

    Charney Anchilyn Davy

    2010-01-01

    It is desirable to use nanostructured composites to produce high-strength, high-conductive materials for magnet development. In this research, severe plastic deformation (e ? 2.0) is used to produce nanostructured Cu-Ag composites in an off-eutectic (Cu-16at%Ag) and an eutectic (Cu-60at%Ag) composite. These two compositions are chosen in order to obtain a better understanding of the off-eutectic microstructure which is comprised of

  17. Synthesis and characterization of LiFePO 4 \\/3-dimensional carbon nanostructure composites as possible cathode materials for Li-ion batteries

    Microsoft Academic Search

    Lucangelo Dimesso; Christina Spanheimer; Susanne Jacke; Wolfram Jaegermann

    2011-01-01

    Composites of three-dimensional (3D) carbon nanostructures coated with olivine-structured lithium iron phosphates (LiFePO4) as cathode materials for lithium ion batteries have been prepared through a Pechini-assisted reversed polyol process for\\u000a the first time. The coating has been successfully performed on nonfunctionalized commercially available 3D carbon used as\\u000a catalysts. Thermal analysis revealed no phase transitions till crystallization occurred at 579 °C. Morphological

  18. Nanostructured polyaniline rice husk composite as adsorption materials synthesized by different methods

    NASA Astrophysics Data System (ADS)

    Tot Pham, Thi; Thanh Thuy Mai, Thi; Quy Bui, Minh; Mai, Thi Xuan; Yen Tran, Hai; Binh Phan, Thi

    2014-03-01

    Composites based on polyaniline (PANi) and rice husk (RH) were prepared by two methods: the first one was chemical method by combining RH contained in acid medium and aniline using ammonium persulfate as an oxidation agent and the second one was that of soaking RH into PANi solution. The presence of PANi combined with RH to form nanocomposite was clearly demonstrated by infrared (IR) spectra as well as by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. Lead(II) and cadmium(II) ion concentrations in solution before and after adsorption process on those composites were analysed by atomic adsorption spectroscopy. Of the above preparation methods, the soaking one provided a composite onto which the maximum adsorption capacity was higher for lead(II) ion (200 mg g?1), but lower for cadmium(II) ion (106.383 mg g?1) in comparison with the chemical one. However, their adsorption process occurring on both composites also fitted well into the Langmuir isotherm model.

  19. Nanostructured thin film thermoelectric composite materials using conductive polymer PEDOT:PSS

    E-print Network

    Kuryak, Chris A. (Chris Adam)

    2013-01-01

    Thermoelectric materials have the ability to convert heat directly into electricity. This clean energy technology has advantages over other renewable technologies in that it requires no sunlight, has no moving parts, and ...

  20. Nanostructured composite material graphite/TiO2 and its antibacterial activity under visible light irradiation.

    PubMed

    D?dková, Kate?ina; Lang, Jaroslav; Mat?jová, Kate?ina; Peikertová, Pavlína; Holešinský, Jan; Vodárek, Vlastimil; Kukutschová, Jana

    2015-08-01

    The paper addresses laboratory preparation, characterization and in vitro evaluation of antibacterial activity of graphite/TiO2 nanocomposites. Composites graphite/TiO2 with various ratio of TiO2 nanoparticles (30wt.%, and 50wt.%) to graphite were prepared using a thermal hydrolysis of titanylsulfate in the presence of graphite particles, and subsequently dried at 80°C. X-ray powder diffraction, transmission electron microscopy and Raman microspectroscopy served as phase-analytical methods distinguishing anatase and rutile phases in the prepared composites. Scanning and transmission electron microscopy techniques were used for characterization of morphology of the prepared samples. A developed modification of the standard microdilution test was used for in vitro evaluation of daylight induced antibacterial activity, using four common human pathogenic bacterial strains (Staphylococcus aureus, Escherichia coli, Enterococcus faecalis and Pseudomonas aeruginosa). Antibacterial activity of the graphite/TiO2 nanocomposites could be based mainly on photocatalytic reaction with subsequent potential interaction of reactive oxygen species with bacterial cells. During the antibacterial activity experiments, the graphite/TiO2 nanocomposites exhibited antibacterial activity, where differences in the onset of activity and activity against bacterial strains were observed. The highest antibacterial activity evaluated as minimum inhibitory concentration was observed against P. aeruginosa after 180min of irradiation. PMID:26114221

  1. Nanomechanical modeling of the nanostructures and dispersed composites

    Microsoft Academic Search

    S. Lurie; P. Belov; D. Volkov-Bogorodsky; N. Tuchkova

    2003-01-01

    Nanoparticles, hyperthin films, nanotubes and composite materials obtained on the base of such nanostructures exhibit very attractive mechanical properties and are great interest to researchers from continuum mechanics. In this paper, we intend to develop the multiscale continuum model of solids to explain the uncommon properties of the thin structures and the composite materials with thin structures associated with special

  2. Composite Materials

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Langley Research Center researchers invented an advanced polymer, a chemical compound formed by uniting many small molecules to create a complex molecule with different chemical properties. The material is a thermoplastic polyimide that resists solvents. Other polymers of this generic type are soluble in solvents, thus cannot be used where solvents are present. High Technology Services (HTS), Inc. licensed technology and is engaged in development and manufacture of high performance plastics, resins and composite materials. Techimer Materials Division is using technology for composite matrix resins that offer heat resistance and protection from radiation, electrical and chemical degradation. Applications of new polymer include molding resins, adhesives and matrix resins for fiber reinforced composites.

  3. Nanostructured materials for photon detection

    NASA Astrophysics Data System (ADS)

    Konstantatos, Gerasimos; Sargent, Edward H.

    2010-06-01

    The detection of photons underpins imaging, spectroscopy, fibre-optic communications and time-gated distance measurements. Nanostructured materials are attractive for detection applications because they can be integrated with conventional silicon electronics and flexible, large-area substrates, and can be processed from the solution phase using established techniques such as spin casting, spray coating and layer-by-layer deposition. In addition, their performance has improved rapidly in recent years. Here we review progress in light sensing using nanostructured materials, focusing on solution-processed materials such as colloidal quantum dots and metal nanoparticles. These devices exhibit phenomena such as absorption of ultraviolet light, plasmonic enhancement of absorption, size-based spectral tuning, multiexciton generation, and charge carrier storage in surface and interface traps.

  4. Nanostructured materials for photon detection.

    PubMed

    Konstantatos, Gerasimos; Sargent, Edward H

    2010-06-01

    The detection of photons underpins imaging, spectroscopy, fibre-optic communications and time-gated distance measurements. Nanostructured materials are attractive for detection applications because they can be integrated with conventional silicon electronics and flexible, large-area substrates, and can be processed from the solution phase using established techniques such as spin casting, spray coating and layer-by-layer deposition. In addition, their performance has improved rapidly in recent years. Here we review progress in light sensing using nanostructured materials, focusing on solution-processed materials such as colloidal quantum dots and metal nanoparticles. These devices exhibit phenomena such as absorption of ultraviolet light, plasmonic enhancement of absorption, size-based spectral tuning, multiexciton generation, and charge carrier storage in surface and interface traps. PMID:20473301

  5. Composite material

    Microsoft Academic Search

    Stacy A. Hutchens; Jonathan Woodward; Barbara R. Evans; Hugh M. ONeill

    2012-01-01

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft

  6. Inorganic-based sol–gel synthesis of nano-structured LiFePO 4 \\/C composite materials for lithium ion batteries

    Microsoft Academic Search

    Jun Ma; Baohua Li; Hongda Du; Chengjun Xu; Feiyu Kang

    An inorganic and non-toxic compounds combination of FeCl2·4H2O, Li2CO3 and H3PO4 was chosen to synthesize homogeneous nano-structured LiFePO4\\/C composite material via a simplified sol–gel route. The dependency of the physicochemical properties and the corresponding\\u000a electrochemical responses on the residual carbon content were investigated in details. Rietveld refinement of X-ray diffraction\\u000a measurement and X-ray photoelectron spectroscopy analysis confirmed the feasibility of

  7. Nanostructured cathode materials for rechargeable lithium batteries

    NASA Astrophysics Data System (ADS)

    Myung, Seung-Taek; Amine, Khalil; Sun, Yang-Kook

    2015-06-01

    The prospect of drastic climate change and the ceaseless fluctuation of fossil fuel prices provide motivation to reduce the use of fossil fuels and to find new energy conversion and storage systems that are able to limit carbon dioxide generation. Among known systems, lithium-ion batteries are recognized as the most appropriate energy storage system because of their high energy density and thus space saving in applications. Introduction of nanotechnology to electrode material is beneficial to improve the resulting electrode performances such as capacity, its retention, and rate capability. The nanostructure is highly available not only when used alone but also is more highlighted when harmonized in forms of core-shell structure and composites with carbon nanotubes, graphene or reduced graphene oxides. This review covers syntheses and electrochemical properties of nanoscale, nanosized, and nanostructured cathode materials for rechargeable lithium batteries.

  8. Composite material

    DOEpatents

    Hutchens, Stacy A. (Knoxville, TN); Woodward, Jonathan (Solihull, GB); Evans, Barbara R. (Oak Ridge, TN); O'Neill, Hugh M. (Knoxville, TN)

    2012-02-07

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

  9. Mechanosynthesis of Nanostructured Materials

    Microsoft Academic Search

    G. LE CAER; S. Begin-Colin; P. Delcroix

    \\u000a In Lilliput, Gulliver noted that “there are some laws and customs in this Empire very peculiar” [1], an observation which might be appropriate for nanophased materials too. Nanophased materials behave indeed differently\\u000a from their macroscopic counterparts because their characteristic sizes are smaller than the characteristic length scales of\\u000a physical phenomena occurring in bulk materials. Hereafter, we shall focus on consolidated

  10. Preparation and characterization of nanostructured MWCNT-TiO{sub 2} composite materials for photocatalytic water treatment applications

    SciTech Connect

    Wang Wendong [Laboratorio de Catalise e Materiais, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n 4200-465 Porto (Portugal); Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Serp, Philippe; Kalck, Philippe [Laboratoire de Chimie de Coordination UPR 8241 CNRS, Ecole Nationale Superieure d'Ingenieurs en Arts Chimiques Et Technologiques, 118 Route de Narbonne Toulouse Cedex 31077 (France); Silva, Claudia Gomes [Laboratorio de Catalise e Materiais, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n 4200-465 Porto (Portugal); Faria, Joaquim Luis [Laboratorio de Catalise e Materiais, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n 4200-465 Porto (Portugal)], E-mail: jlfaria@fe.up.pt

    2008-04-01

    Nanoscale composite materials containing multi-walled carbon nanotubes (MWCNT) and titania were prepared by using a modified sol-gel method. The composites were comprehensively characterized by thermogravimetric analysis, nitrogen adsorption-desorption isotherm, powder X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis absorption spectroscopy. The analysis revealed the presence of titania crystallites of about 7.5 nm aggregated together with MWCNT in particles of 15-20 nm of diameter. The photoactivity of the prepared materials, under UV or visible irradiation, was tested using the conversion of phenol from model aqueous solutions as probe reaction. A synergy effect on the photocatalytic activities observed for the composite catalysts was discussed in terms of a strong interphase interaction between carbon and TiO{sub 2} phases by comparing the different roles of MWCNT in the composite materials.

  11. Application opportunities for nanostructured materials and coatings

    Microsoft Academic Search

    Maurice Gell

    1995-01-01

    Nanostructured materials have the potential to change materials science as we know it today significantly, as well as to provide a new generation of materials with a quantum improvement in properties. While many interesting properties have been generated in the laboratory, there is still much work to be done before there are production applications for nanostructured materials and coatings in

  12. Quantitative Characterization of Nanostructured Materials

    SciTech Connect

    Dr. Frank (Bud) Bridges, University of California-Santa Cruz

    2010-08-05

    The two-and-a-half day symposium on the "Quantitative Characterization of Nanostructured Materials" will be the first comprehensive meeting on this topic held under the auspices of a major U.S. professional society. Spring MRS Meetings provide a natural venue for this symposium as they attract a broad audience of researchers that represents a cross-section of the state-of-the-art regarding synthesis, structure-property relations, and applications of nanostructured materials. Close interactions among the experts in local structure measurements and materials researchers will help both to identify measurement needs pertinent to â??real-worldâ? materials problems and to familiarize the materials research community with the state-of-the-art local structure measurement techniques. We have chosen invited speakers that reflect the multidisciplinary and international nature of this topic and the need to continually nurture productive interfaces among university, government and industrial laboratories. The intent of the symposium is to provide an interdisciplinary forum for discussion and exchange of ideas on the recent progress in quantitative characterization of structural order in nanomaterials using different experimental techniques and theory. The symposium is expected to facilitate discussions on optimal approaches for determining atomic structure at the nanoscale using combined inputs from multiple measurement techniques.

  13. Preparation and characterization of nanostructured MWCNT-TiO 2 composite materials for photocatalytic water treatment applications

    Microsoft Academic Search

    Wendong Wang; Philippe Serp; Philippe Kalck; Cláudia Gomes Silva; Joaquim Luís Faria

    2008-01-01

    Nanoscale composite materials containing multi-walled carbon nanotubes (MWCNT) and titania were prepared by using a modified sol–gel method. The composites were comprehensively characterized by thermogravimetric analysis, nitrogen adsorption–desorption isotherm, powder X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy, X-ray photoelectron spectroscopy and UV–vis absorption spectroscopy. The analysis revealed the presence of titania crystallites of about

  14. Nanostructured Materials: Symthesis in Supercritical Fluids

    SciTech Connect

    Lin, Yuehe; Ye, Xiangrong; Wai, Chien M.

    2009-03-24

    This chapter summarizes the recent developent of synthesis and characterization of nanostructured materials synthesized in supercritical fluids. Nanocomposite catalysts such as Pt and Pd on carbon nanotube support have been synthesized and used for fuel cell applications.

  15. Nanostructured materials for electrodes in lithium-ion batteries

    Microsoft Academic Search

    See How Ng

    2007-01-01

    The commercially available lithium-ion cells, which are the most advanced among the rechargeable battery systems available so far, employ polycrystalline microsized powder as the electrode materials, which functions as the Li-ion insertion hosts. With the advancement of nanotechnology, there is an interest in the replacement of conventional materials by nanostructured materials. The use of nanoparticles in composite electrodes for Li-ion

  16. Nanostructured hybrid materials from aqueous polymer dispersions.

    PubMed

    Castelvetro, Valter; De Vita, Cinzia

    2004-05-20

    Organic-inorganic (O-I) hybrids with well-defined morphology and structure controlled at the nanometric scale represent a very interesting class of materials both for their use as biomimetic composites and because of their potential use in a wide range of technologically advanced as well as more conventional application fields. Their unique features can be exploited or their role envisaged as components of electronic and optoelectronic devices, in controlled release and bioencapsulation, as active substrates for chromatographic separation and catalysis, as nanofillers for composite films in packaging and coating, in nanowriting and nanolithography, etc. A synergistic combination or totally new properties with respect to the two components of the hybrid can arise from nanostructuration, achieved by surface modification of nanostructures, self-assembling or simply heterophase dispersion. In fact, owing to the extremely large total surface area associated with the resulting morphologies, the interfacial interactions can deeply modify the bulk properties of each component. A wide range of starting materials and of production processes have been studied in recent years for the controlled synthesis and characterization of hybrid nanostructures, from nanoparticle or lamellar dispersions to mesoporous materials obtained from templating nanoparticle dispersions in a continuous, e.g. ceramic precursor, matrix. This review is aimed at giving some basic definitions of what is intended as a hybrid (O-I) material and what are the main synthetic routes available. The various methods for preparing hybrid nanostructures and, among them, inorganic-organic or O-I core-shell nanoparticles, are critically analyzed and classified based on the reaction medium (aqueous, non-aqueous), and on the role it plays in directing the final morphology. Particular attention is devoted to aqueous systems and water-borne dispersions which, in addition to being environmentally more acceptable or even a mandatory choice for any future development of large output applications (e.g. in paint, ink and coating industry), can provide the thermodynamic drive for self-assembling of amphiphilics, adsorption onto colloidal particles or partitioning of the hybrid's precursors between dispersed nanosized reaction loci, as in emulsion or miniemulsion free-radical polymerization. While nanoencapsulation and self-assembling processes are already exploited as commercially viable fabrication methods, a newly developed technique based on two-stage sol-gel and free-radical emulsion polymerization is described, which can grant a versatile synthetic approach to hybrid O-I nanoparticles with tailor-made composition of both the organic core and the silica or organosilica shell, and good control on morphology, size and heterophase structure in the 50-500 nm range. Styrene or acrylate homo- and copolymer core latex particles need to be modified with a reactive comonomer, such as trimethoxysilylpropyl methacrylate, to achieve efficient interfacial coupling with the inorganic shell. Accurate control over pH and process conditions is required to avoid latex coagulation or, in case of organic particles with uniform composition, incipient intraparticle crosslinking. PMID:15072940

  17. Inflammatory Response to Implanted Nanostructured Materials

    Microsoft Academic Search

    Kristy M. Ainslie; Rahul G. Thakar; Daniel A. Bernards; Tejal A. Desai

    Nanostructured materials are implanted for dynamic application in therapies such as drug delivery, tissue engineering, biosensing,\\u000a and imaging. The interaction between nanostructured materials and the tissues of the body can be used to alter cellular attachment\\u000a and motility, detect analytes in vivo, and simulate tissue organization. These interactions may also lead to a variety of\\u000a adverse immune responses, such as

  18. Chemistry and Processing of Nanostructured Materials

    SciTech Connect

    Fox, G A; Baumann, T F; Hope-Weeks, L J; Vance, A L

    2002-01-18

    Nanostructured materials can be formed through the sol-gel polymerization of inorganic or organic monomer systems. For example, a two step polymerization of tetramethoxysilane (TMOS) was developed such that silica aerogels with densities as low as 3 kg/m{sup 3} ({approx} two times the density of air) could be achieved. Organic aerogels based upon resorcinol-formaldehyde and melamine-formaldehyde can also be prepared using the sol-gel process. Materials of this type have received significant attention at LLNL due to their ultrafine cell sizes, continuous porosity, high surface area and low mass density. For both types of aerogels, sol-gel polymerization depends upon the transformation of these monomers into nanometer-sized clusters followed by cross-linking into a 3-dimensional gel network. While sol-gel chemistry provides the opportunity to synthesize new material compositions, it suffers from the inability to separate the process of cluster formation from gelation. This limitation results in structural deficiencies in the gel that impact the physical properties of the aerogel, xerogel or nanocomposite. In order to control the properties of the resultant gel, one should be able to regulate the formation of the clusters and their subsequent cross-linking. Towards this goal, we are utilizing dendrimer chemistry to separate the cluster formation from the gelation so that new nanostructured materials can be produced. Dendrimers are three-dimensional, highly branched macromolecules that are prepared in such a way that their size, shape and surface functionality are readily controlled. The dendrimers will be used as pre-formed clusters of known size that can be cross-linked to form an ordered gel network.

  19. Nanostructured Diclofenac Sodium Releasing Material

    NASA Astrophysics Data System (ADS)

    Nikkola, L.; Vapalahti, K.; Harlin, A.; Seppälä, J.; Ashammakhi, N.

    2008-02-01

    Various techniques have been developed to produce second generation biomaterials for tissue repair. These include extrusion, molding, salt leaching, spinning etc, but success in regenerating tissues has been limited. It is important to develop porous material, yet with a fibrous structure for it to be biomimetic. To mimic biological tissues, the extra-cellular matrix usually contains fibers in nano scale. To produce nanostructures, self-assembly or electrospinning can be used. Adding a drug release function to such a material may advance applications further for use in controlled tissue repair. This turns the resulting device into a multifunctional porous, fibrous structure to support cells and drug releasing properties in order to control tissue reactions. A bioabsorbable poly(?-caprolactone-co-D,L lactide) 95/5 (PCL) was made into diluted solution using a solvent, to which was added 2w-% of diclofenac sodium (DS). Nano-fibers were made by electrospinning onto substrate. Microstructure of the resulting nanomat was studied using SEM and drug release profiles with UV/VIS spectroscopy. Thickness of the electrospun nanomat was about 2 mm. SEM analysis showed that polymeric nano-fibers containing drug particles form a highly interconnected porous nano structure. Average diameter of the nano-fibers was 130 nm. There was a high burst peak in drug release, which decreased to low levels after one day. The used polymer has slow a degradation rate and though the nanomat was highly porous with a large surface area, drug release rate is slow. It is feasible to develop a nano-fibrous porous structure of bioabsorbable polymer, which is loaded with test drug. Drug release is targeted at improving the properties of biomaterial for use in controlled tissue repair and regeneration.

  20. Composite Materials

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Composites are lighter and stronger than metals. Aramid fibers like Kevlar and Nomex were developed by DuPont Corporation and can be combined in a honeycomb structure which can give an airplane a light, tough structure. Composites can be molded into many aerodynamic shapes eliminating rivets and fasteners. Langley Research Center has tested composites for both aerospace and non-aerospace applications. They are also used in boat hulls, military shelters, etc.

  1. Shockwave consolidation of nanostructured thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Prasad, Narasimha S.; Taylor, Patrick; Nemir, David

    2014-09-01

    Nanotechnology based thermoelectric materials are considered attractive for developing highly efficient thermoelectric devices. Nano-structured thermoelectric materials are predicted to offer higher ZT over bulk materials by reducing thermal conductivity and increasing electrical conductivity. Consolidation of nano-structured powders into dense materials without losing nanostructure is essential towards practical device development. Using the gas atomization process, amorphous nano-structured powders were produced. Shockwave consolidation is accomplished by surrounding the nanopowder-containing tube with explosives and then detonated. The resulting shock wave causes rapid fusing of the powders without the melt and subsequent grain growth. We have been successful in generating consolidated nanostructured bismuth telluride alloy powders by using shockwave technique. Using these consolidated materials, several types of thermoelectric power generator devices have been developed. Shockwave consolidation is anticipated to generate large quantities of nanostructred materials expeditiously and cost effectively. In this paper, the technique of shockwave consolidation will be presented followed by Seebeck Coefficient and thermal conductivity measurements of consolidated materials. Preliminary results indicate a substantial increase in electrical conductivity due to shockwave consolidation technique.

  2. Shockwave Consolidation of Nanostructured Thermoelectric Materials

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Taylor, Patrick; Nemir, David

    2014-01-01

    Nanotechnology based thermoelectric materials are considered attractive for developing highly efficient thermoelectric devices. Nano-structured thermoelectric materials are predicted to offer higher ZT over bulk materials by reducing thermal conductivity and increasing electrical conductivity. Consolidation of nano-structured powders into dense materials without losing nanostructure is essential towards practical device development. Using the gas atomization process, amorphous nano-structured powders were produced. Shockwave consolidation is accomplished by surrounding the nanopowder-containing tube with explosives and then detonating. The resulting shock wave causes rapid fusing of the powders without the melt and subsequent grain growth. We have been successful in generating consolidated nano-structured bismuth telluride alloy powders by using the shockwave technique. Using these consolidated materials, several types of thermoelectric power generating devices have been developed. Shockwave consolidation is anticipated to generate large quantities of nanostructred materials expeditiously and cost effectively. In this paper, the technique of shockwave consolidation will be presented followed by Seebeck Coefficient and thermal conductivity measurements of consolidated materials. Preliminary results indicate a substantial increase in electrical conductivity due to shockwave consolidation technique.

  3. Cucurbituril-based supramolecular engineered nanostructured materials.

    PubMed

    Gürbüz, Sinem; Idris, Muazzam; Tuncel, Dönüs

    2015-01-14

    Cucurbituril (CB) is a unique macrocycle with a rigid symmetrical structure, which is composed of two identical hydrophilic portals decorated with partially negatively charged carbonyl groups and a hydrophobic cavity. A number of different nanostructured materials, including nanoparticles, nanocomposites, vesicles and rods, have been prepared by taking advantage of the varying cavity size of the CB homologues, their ability to accommodate more than one guest in their cavities, their rigid symmetrical structures, as well as the water solubility of CB7. These nanostructures could find a wide range of potential applications in the areas of self-healing materials, nanomedicine, plasmonics, and nanocatalysis. Here, we review the recent progresses in the synthesis, properties and application of CB-based supramolecular engineered nanostructures, which are either constructed through CB-assisted self-assembly or from post-functionalized-CB homologues. PMID:25408267

  4. JOM, 2013, Vol. 65, No. 2, pp. TBD. Modeling and simulation in composite materials integration from nanostructure to component level

    E-print Network

    Gupta, Nikhil

    that can accurately predict mechanical, thermal, electrical, optical, or a combination of these properties are multi-phase materials comprising a matrix reinforced with one or more types of fibers and particles aircraft structures for several major aircraft models. After the initial surge in the applications

  5. Nanostructured materials in the food industry.

    PubMed

    Augustin, Mary Ann; Sanguansri, Peerasak

    2009-01-01

    Nanotechnology involves the application, production, and processing of materials at the nanometer scale. Biological- and physical-inspired approaches, using both conventional and innovative food processing technologies to manipulate matter at this scale, provide the food industry with materials with new functionalities. Understanding the assembly behavior of native and modified food components is essential in developing nanostructured materials. Functionalized nanostructured materials are finding applications in many sectors of the food industry, including novel nanosensors, new packaging materials with improved mechanical and barrier properties, and efficient and targeted nutrient delivery systems. An improved understanding of the benefits and the risks of the technology based on sound scientific data will help gain the acceptance of nanotechnology by the food industry. New horizons for nanotechnology in food science may be achieved by further research on nanoscale structures and methods to control interactions between single molecules. PMID:19878860

  6. Composite Materials Handbook

    NSDL National Science Digital Library

    From the US Army Research Laboratory, Materials Sciences Corporation, and University of Delaware Center for Composite Materials, the Composite Materials Handbook provides the "information and guidance necessary to design and fabricate end items from composite materials." Along with current information on the material properties of these composite materials, the handbook also includes data development and usage guidelines. The information has been divided into three areas: polymer, metal, and ceramic matrix composites. The Polymer Matrix Composites Handbook (three volumes including Guidelines for Characterization of Structural Materials; Material Properties; and Materials Usage, Design, and Analysis) and the Metal Matrix Composites Handbook (one volume, .pdf) are available here. The Ceramic Matrix Composites Handbook has yet to be completed. Users may also download Quick Composites Data in spreadsheet format.

  7. Nanostructure studies of strongly correlated materials

    NASA Astrophysics Data System (ADS)

    Wei, Jiang; Natelson, Douglas

    2011-09-01

    Strongly correlated materials exhibit an amazing variety of phenomena, including metal-insulator transitions, colossal magnetoresistance, and high temperature superconductivity, as strong electron-electron and electron-phonon couplings lead to competing correlated ground states. Recently, researchers have begun to apply nanostructure-based techniques to this class of materials, examining electronic transport properties on previously inaccessible length scales, and applying perturbations to drive systems out of equilibrium. We review progress in this area, particularly emphasizing work in transition metal oxides (Fe3O4, VO2), manganites, and high temperature cuprate superconductors. We conclude that such nanostructure-based studies have strong potential to reveal new information about the rich physics at work in these materials.

  8. Optical spectroscopy of nanostructured materials

    Microsoft Academic Search

    Ryan Douglas Hartschuh

    2007-01-01

    Significant interest in nanotechnology is stimulated by the fact that materials exhibit qualitative changes of properties when their dimensions approach nanometer scales. Quantization of electronic, optical, and acoustic energies with nanoscale dimensions provides exciting, novel functions and opportunities, with interests spanning from electronics and photonics to biology. Characterizing the behavior of nanoscale materials is critical for the full utilization of

  9. Nanostructure material for supercapacitor application

    SciTech Connect

    Huang, Y.; Chu, C.T.; Wei, Q.; Zheng, H.

    2000-07-01

    Transition metal nitrides and carbonitride materials were fabricated via sol-gel technology. The transition metal amides were synthesized by two methods: chemical route and electrolysis. The transition metal amides were then further polymerized, sintering to high temperature in an inert or reduced atmosphere. Transition metal nitrides and carbonitrides powders with surface area up to 160 m{sup 2}/g were obtained. The resultant electrode material showed high specific capacitance as crystalline ruthenium oxide.

  10. Nanostructured carbonaceous materials from molecular precursors.

    PubMed

    Hoheisel, Tobias N; Schrettl, Stephen; Szilluweit, Ruth; Frauenrath, Holger

    2010-09-01

    Nanostructured carbonaceous materials, that is, carbon materials with a feature size on the nanometer scale and, in some cases, functionalized surfaces, already play an important role in a wide range of emerging fields, such as the search for novel energy sources, efficient energy storage, sustainable chemical technology, as well as organic electronic materials. Furthermore, such materials might offer solutions to the challenges associated with the on-going depletion of nonrenewable energy resources or climate change, and they may promote further breakthroughs in the field of microelectronics. However, novel methods for their preparation will be required that afford functional carbon materials with controlled surface chemistry, mesoscopic morphology, and microstructure. A highly promising approach for the synthesis of such materials is based on the use of well-defined molecular precursors. PMID:20661971

  11. Chapter 5 Nanostructured Materials in the Food Industry

    Microsoft Academic Search

    Mary Ann Augustin; Peerasak Sanguansri

    2009-01-01

    Nanotechnology involves the application, production, and processing of materials at the nanometer scale. Biological- and physical-inspired approaches, using both conventional and innovative food processing technologies to manipulate matter at this scale, provide the food industry with materials with new functionalities. Understanding the assembly behavior of native and modified food components is essential in developing nanostructured materials. Functionalized nanostructured materials are

  12. Mechanics of composite materials

    SciTech Connect

    Dvorak, G.J. (Inst. Center for Composite Materials and Structures, Rensselaer Polytechnic Inst. (US)); Laws, N. (Dept. of Mechanical Engineering, Univ. of Pittsburgh, PA (US))

    1988-01-01

    This book contains the following papers: crack growth resistance of TiB{sub 2} particulate/SiC matrix composite; constitutive relations of flexible composites under elastic deformation; determination of two kinds of composite plasticity: inclusions plastic vs. matrix plastic; 3-D analysis of transient interlaminar thermal stress of laminated composites; effect of seawater on the fracture toughness of pultruded rods; evaluation of new failure criterion for fibrous composite materials; and bridged cracks in fiber-reinforced composites.

  13. Composite material dosimeters

    DOEpatents

    Miller, Steven D. (Richland, WA)

    1996-01-01

    The present invention is a composite material containing a mix of dosimeter material powder and a polymer powder wherein the polymer is transparent to the photon emission of the dosimeter material powder. By mixing dosimeter material powder with polymer powder, less dosimeter material is needed compared to a monolithic dosimeter material chip. Interrogation is done with excitation by visible light.

  14. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1983-01-01

    Transverse properties of fiber constituents in composites, fatigue in composite materials, matrix dominated properties of high performance composites, numerical investigation of moisture effects, numerical investigation of the micromechanics of composite fracture, advanced analysis methods, compact lug design, and the RP-1 and RP-2 sailplanes projects are discussed.

  15. Benzoxazine resin/carbon nanotube nanostructured composite's degradation kinetic.

    PubMed

    Untem, Flávia O; Botelho, Edson C; Rezende, Mirabel C; Costa, Michelle Leali

    2014-07-01

    In the last decades a new class of thermoset phenolic resin is emerging as a substitute of the traditional epoxy and phenolic resins in the aircraft industry. This new class is called polybenzoxazines and its associates the epoxy resin's mechanical properties and phenolic resin's thermal and flame retardant properties, resulting in a resin with superior properties when analyzed with the others singly. The introduction of carbon nanotubes in low concentration into polymeric matrices can produce nanostructured materials with good properties. Thus, in this study, nanostructured composites of benzoxazine resin were processed with different concentration of carbon nanotubes (0.1%, 0.5% and 1.0% w/w). In order to evaluate the thermostability of the benzoxazine resin and its nanostructured composites, it was performed a degradation kinetic study using the thermogravimetric technique. For that, the analysis have been done with the temperature ranging from 25 degrees C to 1000 degrees C at nitrogen atmosphere (100 mL x min(-1)) and in different heating rates (2, 4, 6, 8, 10 and 20 degrees C x min(-1)), in order to obtain the kinetic parameters (activation energy, E(a), and pre-exponential factor, A), based on Ozawa-Wall-Flynn model. The results showed excellent agreement between the thermogravimetric curves obtained and the Ozawa-Wall-Flynn method. The degradation kinetic study showed that the introduction of carbon nanotubes in the benzoxazine matrix does not change the thermostability of the resin, so that it does not have a significant influence in the shelf life of the material. PMID:24757993

  16. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1979-01-01

    Technology utilization of fiber reinforced composite materials is discussed in the areas of physical properties, and life prediction. Programs related to the Composite Aircraft Program are described in detail.

  17. Tough Composite Materials

    NASA Technical Reports Server (NTRS)

    Vosteen, L. F. (compiler); Johnson, N. J. (compiler); Teichman, L. A. (compiler)

    1984-01-01

    Papers and working group summaries are presented which address composite material behavior and performance improvement. Topic areas include composite fracture toughness and impact characterization, constituent properties and interrelationships, and matrix synthesis and characterization.

  18. Nano-composite materials

    DOEpatents

    Lee, Se-Hee; Tracy, C. Edwin; Pitts, J. Roland

    2010-05-25

    Nano-composite materials are disclosed. An exemplary method of producing a nano-composite material may comprise co-sputtering a transition metal and a refractory metal in a reactive atmosphere. The method may also comprise co-depositing a transition metal and a refractory metal composite structure on a substrate. The method may further comprise thermally annealing the deposited transition metal and refractory metal composite structure in a reactive atmosphere.

  19. Geometric and compositional influences on spin-orbit induced circulating currents in nanostructures

    NASA Astrophysics Data System (ADS)

    van Bree, J.; Silov, A. Yu.; Koenraad, P. M.; Flatté, M. E.

    2014-10-01

    Circulating orbital currents, originating from the spin-orbit interaction, are calculated for semiconductor nanostructures in the shape of spheres, disks, spherical shells, and rings for the electron ground state with spin oriented along a symmetry axis. The currents and resulting orbital and spin magnetic moments, which combine to yield the effective electron g factor, are calculated using a recently introduced formalism that allows the relative contributions of different regions of the nanostructure to be identified at zero magnetic field. For all these spherically or cylindrically symmetric hollow or solid nanostructures, independent of material composition and whether the boundary conditions are hard or soft, the dominant orbital current originates from intermixing of valence-band states in the electron ground state, circulates within the nanostructure, and peaks approximately halfway between the center and edge of the nanostructure in the plane perpendicular to the spin orientation. For a specific material composition and confinement character, the confinement energy and orbital moment are determined by a single size-dependent parameter for spherically symmetrical nanostructures, whereas they can be independently tuned for cylindrically symmetric nanostructures.

  20. Nanostructured Materials Development for Space Power

    NASA Technical Reports Server (NTRS)

    Raffaelle, Ryne P.; Landi, B. J.; Elich, J. B.; Gennett, T.; Castro, S. L.; Bailey, Sheila G.; Hepp, Aloysius F.

    2003-01-01

    There have been many recent advances in the use of nanostructured materials for space power applications. In particular, the use of high purity single wall nanotubes holds promise for a variety of generation and storage devices including: thin film lithium ion batteries, microelectronic proton exchange membrane (PEM) fuel cells, polymeric thin film solar cells, and thermionic power supplies is presented. Semiconducting quantum dots alone and in conjunction with carbon nanotubes are also being investigated for possible use in high efficiency photovoltaic solar cells. This paper will review some of the work being done at RIT in conjunction with the NASA Glenn Research Center to utilize nanomaterials in space power devices.

  1. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1979-01-01

    A multifaceted program is described in which aeronautical, mechanical, and materials engineers interact to develop composite aircraft structures. Topics covered include: (1) the design of an advanced composite elevator and a proposed spar and rib assembly; (2) optimizing fiber orientation in the vicinity of heavily loaded joints; (3) failure mechanisms and delamination; (4) the construction of an ultralight sailplane; (5) computer-aided design; finite element analysis programs, preprocessor development, and array preprocessor for SPAR; (6) advanced analysis methods for composite structures; (7) ultrasonic nondestructive testing; (8) physical properties of epoxy resins and composites; (9) fatigue in composite materials, and (10) transverse thermal expansion of carbon/epoxy composites.

  2. Wear corrosion properties of nano-structured SiC–nickel composite coatings obtained by electroplating

    Microsoft Academic Search

    Lidia Benea; Pier Luigi Bonora; Alberto Borello; Stefano Martelli

    2001-01-01

    Advances in materials performance often require the development of composite systems. Coated materials could be one form to use. The abrasion and corrosion resistance of components can be greatly increased by protective coatings and this is a growing industry of considerable economic importance. These paper aims with a comparative wear corrosion study of pure nickel and Ni–SiC nano-structured composite coating.

  3. Final Technical Progress Report NANOSTRUCTURED MAGNETIC MATERIALS

    SciTech Connect

    Charles M. Falco

    2012-09-13

    This report describes progress made during the final phase of our DOE-funded program on Nanostructured Magnetic Materials. This period was quite productive, resulting in the submission of three papers and presentation of three talks at international conferences and three seminars at research institutions. Our DOE-funded research efforts were directed toward studies of magnetism at surfaces and interfaces in high-quality, well-characterized materials prepared by Molecular Beam Epitaxy (MBE) and sputtering. We have an exceptionally well-equipped laboratory for these studies, with: Thin film preparation equipment; Characterization equipment; Equipment to study magnetic properties of surfaces and ultra-thin magnetic films and interfaces in multi-layers and superlattices.

  4. Nanostructure and composition of bivalve shells

    NASA Astrophysics Data System (ADS)

    Jacob, D. E.; Soldati, A. L.; Wirth, R.; Huth, J.; Wehrmeister, U.; Hofmeister, W.

    2009-04-01

    Shells and pearls of unionid mussels (Hyriopsis cumingii, Margaritifera margaritifera, Diplodon chilensis patagonicus) were studied by high resolution microbeam methods and -computer tomography to gather insight into the nanostructure and chemical composition of nacre and prism layers. Natural and cultured pearls are formed by many mollusc species and their generation is very similar to that of shells resulting in identical prismatic and nacreous structures of shells and pearls. Basic difference is, however that pearl culturing methods induce biomineralisation of CaCO3 around a crystalline bead which results in a reverse structural organisation compared to bivalve shells. Bivalve shell growth starts from a thick organic matrix (the periostracum; Eyster and Morse, 1984) which is followed towards the inside by two variously thick layers consisting of prismatic CaCO3 aggregations and layers of CaCO3 platelets, respectively. Platelets and prisms are individually covered by a chitinous organic matrix which lends structural support and is thought to exert control over the mineralization process. The minerals within the organic sheaths are highly-aligned poly-twinned crystals with a slightly distorted lattice due to inclusions of organic molecules (Pokroy et al., 2006). Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and Raman Microscopy analyses of the shells and pearls show that both structures, prisms and platelets, consist of nanometre-sized organic membrane-coated granules of CaCO3 (Jacob et al., 2008). In the vicinity of the periostracum, the granules consist of amorphous calcium carbonate (ACC), but the crystallinity increases with increasing distance from the periostracum. The transition from disordered (amorphous) to crystalline CaCO3 is gradual within a few micrometers and coincides with a decrease in porosity. Concentrations of sulphur and phosphorus are higher in ACC than in aragonite indicating a higher organic content of ACC. Bivalve larval shells were shown to consist entirely of ACC before this phase crystallizes to form aragonite (Weiss, et al., 2002). The occurrence of ACC in pearls and adult shells close to the periostracum reported here and by Jacob et al. (2008) is taken as evidence that bivalve shell formation starts from ACC secreted in organic vesicles. Lately, a number of studies reported similar granular nanostructures for many different mollusc species which implies that shell growth by secretion of ACC vesicles could be a widespread phenomenon in biology. Vaterite could be identified in freshwater cultured pearls as well as in shells of Hyriopsis cumingii and Diplodon chilensis patagonicus. Aragonite and vaterite were found to coexist and are crosscut by growth lines, implying simultaneous formation. In pearls, it was found that vaterite, like aragonite, forms from ACC (Jacob et al., 2008) and is therefore not the precursor phase of aragonite in this system. Eyster L.S. and Morse M. P. (1984). Early shell formation during molluscan embryogenesis, with new studies on the Surf clam, Spisula solidissima. Am. Zoologist 24: 871-882. Jacob, D.E., A.L. Soldati, R. Wirth, J. Huth, U. Wehrmeister und W. Hofmeister (2008). Nanostructure, chemical composition and mechanisms of bivalve shell growth. Geochim. Cosmochim. Acta, 72, 22, 5401-5415. Pokroy B., Fitch A. N., Lee P. L., Quintana J. P., Caspi E. N., and Zolotoyabko E. (2006) Anisotropic lattice distortions in the mollusk-made aragonite: A widespread phenomenon. J. Structural Biology 153, 145-150. Weiss I. M., Tuross N., Addadi L., and Weiner S. (2002) Mollusc larval shell formation: Amorphous calcium carbonate is a precursor phase for aragonite. J. Exp. Zoology 293, 478-491.

  5. 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

  6. Metallic glass nanostructures of tunable shape and composition.

    PubMed

    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

  7. Metallic glass nanostructures of tunable shape and composition

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

  8. Nanostructured photovoltaic materials using block polymer assemblies

    NASA Astrophysics Data System (ADS)

    Mastroianni, Sarah Elizabeth

    Despite its potential as an abundant, sustainable alternative to non-renewable energy sources, solar energy currently is underutilized. Photovoltaics, which convert energy from sunlight into electricity, commonly are made from inorganic semiconductor materials that require expensive manufacturing and processing techniques. Alternatively, organic materials can be used to produce flexible and lightweight organic photovoltaic (OPV) devices, which can be prepared using solution-based processing techniques. However, OPV devices are limited by low efficiencies and short lifetimes compared to their inorganic counterparts. In OPV systems, charge carriers are generated in the active layer via the separation of excitons (electron-hole pairs) at interfaces between donor and acceptor materials. Because excitons have a limited diffusion length (˜10 nm), they may recombine before reaching a donor-acceptor interface if domain sizes are large. This exciton recombination can limit device efficiency; thus, the design parameters for improved active layer morphologies include large interfacial areas, small size scales, and continuous conducting pathways. Currently, most OPV devices are prepared by blending donor and acceptor materials in bulk heterojunction (BHJ) devices, often resulting in non-ideal, process-dependent morphologies. Alternatively, the self-assembly of block polymers (BP)s offers a reproducible means to generate nanostructured active layers. The work presented in this dissertation examines the synthetic approaches to preparing BPs containing different electroactive materials: non-conjugated, amorphous poly(vinyl-m-triphenylamine) [PVmTPA] and conjugated poly(3-alkythiophene) [P3AT] p-type materials as well as fullerene-based n-type materials. The synthesis and self-assembly of a model poly(methyl methacrylate)- b-PVmTPA system is presented. This work was extended to synthesize PVmTPA BPs with complementary poly(methyl methacrylate- co-hydroxyethyl methacrylate) [P(MMA-co-HEMA)] blocks onto which fullerenes were grafted using post-polymerization coupling reactions. P3AT BP synthetic techniques also were explored but largely were limited by P3AT purity and end-functionalization. Nevertheless, reversible addition-fragmentation chain-transfer (RAFT) polymerization offered a viable method to incorporate all three of the examined electroactive materials into BPs. The approaches presented in this dissertation provide the tools to design, synthesize, and characterize new BPs for OPVs that can reproducibly self-assemble into well-defined nanostructures.

  9. Rheological and morphological characterization of hierarchically nanostructured materials

    E-print Network

    Wang, Benjamin Ning-Haw

    2007-01-01

    Hierarchically nanostructured materials exhibit order on multiple length scales, with at least one of a few nanometers. The expected enhancements for applications using these materials include improved mechanical, thermal ...

  10. Optical composite materials

    SciTech Connect

    Beecroft, L.L.; Ober, C.K.; Barber, D.B. [Cornell Univ., Ithaca, NY (United States)] [and others

    1995-12-31

    Optical quality composite materials can be useful for many applications. This work concerns optical quality composite films constructed from very small (<100 nm) particles of optically functional material embedded in a matrix of the same refractive index (RI). The particles impart their optical properties, while the matrix allows for processing of films. The initial optical composite studied contained Cr-forsterite (Cr-Mg{sub 2}SiO{sub 4}), a tunable solid state laser material in the attractive near-IR regime (1167-1345 nm). Small Cr-forsterite particles were synthesized by firing preceramic dispersion polymerization beads, and were embedded in unusually high RI polymeric matrix materials. Work to make optical amplification measurements is underway. This composite concept can be extended to other optically interesting materials.

  11. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Loewy, R.; Wiberley, S. E.

    1986-01-01

    Overall emphasis is on basic long-term research in the following categories: constituent materials, composite materials, generic structural elements, processing science technology; and maintaining long-term structural integrity. Research in basic composition, characteristics, and processing science of composite materials and their constituents is balanced against the mechanics, conceptual design, fabrication, and testing of generic structural elements typical of aerospace vehicles so as to encourage the discovery of unusual solutions to present and future problems. Detailed descriptions of the progress achieved in the various component parts of this comprehensive program are presented.

  12. Electrically conductive composite material

    DOEpatents

    Clough, Roger L. (Albuquerque, NM); Sylwester, Alan P. (Albuquerque, NM)

    1989-01-01

    An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistant pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like.

  13. Electrically conductive composite material

    DOEpatents

    Clough, R.L.; Sylwester, A.P.

    1989-05-23

    An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistent pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like. 2 figs.

  14. Electrically conductive composite material

    DOEpatents

    Clough, R.L.; Sylwester, A.P.

    1988-06-20

    An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistent pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like. 2 figs.

  15. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1982-01-01

    The promise of filamentary composite materials, whose development may be considered as entering its second generation, continues to generate intense interest and applications activity. Fiber reinforced composite materials offer substantially improved performance and potentially lower costs for aerospace hardware. Much progress has been achieved since the initial developments in the mid 1960's. Rather limited applications to primary aircraft structure have been made, however, mainly in a material-substitution mode on military aircraft, except for a few experiments currently underway on large passenger airplanes in commercial operation. To fulfill the promise of composite materials completely requires a strong technology base. NASA and AFOSR recognize the present state of the art to be such that to fully exploit composites in sophisticated aerospace structures, the technology base must be improved. This, in turn, calls for expanding fundamental knowledge and the means by which it can be successfully applied in design and manufacture.

  16. Strength of composite materials

    Microsoft Academic Search

    F. F. Egorov; P. S. Kislyi; P. A. Verkhovodov

    1979-01-01

    1.A study was made of the strength of ZrN-Al2O3 composite materials produced by solid- and liquid-phase sintering in argon and nitrogen. It is shown that the strength of composites sintered in nitrogen is such less than that of composites sintered in argon, which is linked with the formation of new phases at boundaries between dissimilar phases and with a weakening

  17. Composite Material Switches

    NASA Technical Reports Server (NTRS)

    Javadi, Hamid (Inventor)

    2001-01-01

    A device to protect electronic circuitry from high voltage transients is constructed from a relatively thin piece of conductive composite sandwiched between two conductors so that conduction is through the thickness of the composite piece. The device is based on the discovery that conduction through conductive composite materials in this configuration switches to a high resistance mode when exposed to voltages above a threshold voltage.

  18. Nanostructured Materials for Environmental Remediation of Organic Contaminants in Water

    Microsoft Academic Search

    Sherine O. Obare; Gerald J. Meyer

    2004-01-01

    Nanostructured materials have opened new avenues in various scientific fields and are providing novel opportunities in environmental science. The increased surface area-to-volume ratio of nanoparticles, quantum size effects, and the ability to tune surface properties through molecular modification make nanostructures ideal for many environmental remediation applications. We describe herein the fabrication of metal and semiconductor nanoparticles for environmental remediation applications,

  19. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1982-01-01

    Research in the basic composition, characteristics, and processng science of composite materials and their constituents is balanced against the mechanics, conceptual design, fabrication, and testing of generic structural elements typical of aerospace vehicles so as to encourage the discovery of unusual solutions to problems. Detailed descriptions of the progress achieved in the various component parts of his program are presented.

  20. Mechanics of Composite Materials

    Microsoft Academic Search

    Robert M. Jones

    1999-01-01

    The mechanical behavior of composites is traditionally evaluated on both microscopic and macroscopic scale to take into account inhomogeneity. Micromechanics attempts to quantify the interactions of fiber and matrix (reinforcement and resin) on a microscopic scale on par with the diameter of a single fiber. Macromechanics treats composites as homogeneous materials, with mechanical properties representative of the laminate as a

  1. Growth of Carbon Nanostructure Materials Using Laser Vaporization

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehozeky, S.

    2000-01-01

    Since the potential applications of carbon nanotubes (CNT) was discovered in many fields, such as non-structure electronics, lightweight composite structure, and drug delivery, CNT has been grown by many techniques in which high yield single wall CNT has been produced by physical processes including arc vaporization and laser vaporization. In this presentation, the growth mechanism of the carbon nanostructure materials by laser vaporization is to be discussed. Carbon nanoparticles and nanotubes have been synthesized using pulsed laser vaporization on Si substrates in various temperatures and pressures. Two kinds of targets were used to grow the nanostructure materials. One was a pure graphite target and the other one contained Ni and Co catalysts. The growth temperatures were 600-1000 C and the pressures varied from several torr to 500 torr. Carbon nanoparticles were observed when a graphite target was used, although catalysts were deposited on substrates before growing carbon films. When the target contains catalysts, carbon nanotubes (CNT) are obtained. The CNT were characterized by scanning electron microscopy, x-ray diffraction, optical absorption and transmission, and Raman spectroscopy. The temperature-and pressure-dependencies of carbon nanotubes' growth rate and size were investigated.

  2. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Loewy, Robert G.; Wiberley, Stephen E.

    1987-01-01

    The development and application of composite materials to aerospace vehicle structures which began in the mid 1960's has now progressed to the point where what can be considered entire airframes are being designed and built using composites. Issues related to the fabrication of non-resin matrix composites and the micro, mezzo and macromechanics of thermoplastic and metal matrix composites are emphasized. Several research efforts are presented. They are entitled: (1) The effects of chemical vapor deposition and thermal treatments on the properties of pitch-based carbon fiber; (2) Inelastic deformation of metal matrix laminates; (3) Analysis of fatigue damage in fibrous MMC laminates; (4) Delamination fracture toughness in thermoplastic matrix composites; (5) Numerical investigation of the microhardness of composite fracture; and (6) General beam theory for composite structures.

  3. Nano-structured polymer composites and process for preparing same

    DOEpatents

    Hillmyer, Marc; Chen, Liang

    2013-04-16

    A process for preparing a polymer composite that includes reacting (a) a multi-functional monomer and (b) a block copolymer comprising (i) a first block and (ii) a second block that includes a functional group capable of reacting with the multi-functional monomer, to form a crosslinked, nano-structured, bi-continuous composite. The composite includes a continuous matrix phase and a second continuous phase comprising the first block of the block copolymer.

  4. Adaptive Hierarchical Multiscale Framework for Modeling the Deformation of Ultra-Strong Nano-structured Materials

    E-print Network

    Ghoniem, Nasr M.

    : polycrystalline nano-twinned copper inter-connects, and multi-layer nano-composites. We will apply these new tools1 Adaptive Hierarchical Multiscale Framework for Modeling the Deformation of Ultra-Strong Nano/Nanoscale Phenom- enology and Metrology." Nano-structured materials are extremely attractive for applications

  5. Resin composite restorative materials.

    PubMed

    Ilie, N; Hickel, R

    2011-06-01

    This paper surveys the most important developments in resin-based dental composites and focuses on the deficits (e.g. polymerization shrinkage) and strengths of the materials and their clinical implications. Moreover, differences between composite categories, such as hybrid, nanohybrid, microfilled, packable, ormocer-based, silorane-based, polyacid-modified composites (compomers) and flowable composites are highlighted, especially in view of their mechanical behaviour. In addition to the classical dimethacrylate-based composites, special attention is given to alternative monomers, such as siloranes, ormocers or high-molecular-weight dimethacrylate monomers (e.g. dimer acid-based dimethacrylates and tricyclodecane (TCD)-urethane), analysing their advantages, behaviour and abilities. Finally, the paper attempts to establish the needs and wishes of clinicians for further development of resin-based composites. PMID:21564116

  6. Hybrid Metal Oxide–Polymer Nanostructured Composites: Structure and Properties

    Microsoft Academic Search

    Alla Pivkina; Sergey Zavyalov; Joop Schoonman

    Within metal (metal oxide)\\/polymer nanocomposites, nanoparticles reveal specific interparticle interactions and interactions\\u000a with the matrix they are dispersed in [1, 2]. Nanostructured anatase titanium dioxide has attracted widespread attention as\\u000a a photo-electrode in an advanced regenerative dye-sensitised solar cell, referred to as the Grätzel cell [3]. It has been\\u000a shown also that the nanostructured anatase material exhibits an enhancement factor

  7. High volume production of nanostructured materials

    DOEpatents

    Ripley, Edward B. (Knoxville, TN); Morrell, Jonathan S. (Knoxville, TN); Seals, Roland D. (Oak Ridge, TN); Ludtka, Gerard M. (Oak Ridge, TN)

    2009-10-13

    A system and method for high volume production of nanoparticles, nanotubes, and items incorporating nanoparticles and nanotubes. Microwave, radio frequency, or infrared energy vaporizes a metal catalyst which, as it condenses, is contacted by carbon or other elements such as silicon, germanium, or boron to form agglomerates. The agglomerates may be annealed to accelerate the production of nanotubes. Magnetic or electric fields may be used to align the nanotubes during their production. The nanotubes may be separated from the production byproducts in aligned or non-aligned configurations. The agglomerates may be formed directly into tools, optionally in compositions that incorporate other materials such as abrasives, binders, carbon-carbon composites, and cermets.

  8. Variations in nanostructure and composition for controlling the interfacial properties of metal matrix composites and ceramic matrix composites

    Microsoft Academic Search

    J. T. McGinn; B. Singh; T. Mukherji

    1995-01-01

    Interface properties are critical to the strength and toughness of metal matrix composites and ceramic matrix composites. These interfaces provide both diffusion barriers and load transfer functions. The nanostructure across the interface was varied to fulfill conflicting diffusion and load transfer demands. The deposition conditions developed allow nanostructure control of TiN fiber coatings. The TiN coating varied from a dense,

  9. Nanotechnology and health safety--toxicity and risk assessments of nanostructured materials on human health.

    PubMed

    Singh, Surya; Nalwa, Hari Singh

    2007-09-01

    The field of nanotechnology has recently emerged as the most commercially viable technology of this century because of its wide-ranging applications in our daily lives. Man-made nanostructured materials such as fullerenes, nanoparticles, nanopowders, nanotubes, nanowires, nanorods, nanofibers, quantum dots, dendrimers, nanoclusters, nanocrystals, and nanocomposites are globally produced in large quantities due to their wide potential applications, e.g., in skincare and consumer products, healthcare, electronics, photonics, biotechnology, engineering products, pharmaceuticals, drug delivery, and agriculture. Human exposure to these nanostructured materials is inevitable, as they can enter the body through the lungs or other organs via food, drink, and medicine and affect different organs and tissues such as the brain, liver, kidney, heart, colon, spleen, bone, blood, etc., and may cause cytotoxic effects, e.g., deformation and inhibition of cell growth leading to various diseases in humans and animals. Since a very wide variety of nanostructured materials exits, their interactions with biological systems and toxicity largely depend upon their properties, such as size, concentration, solubility, chemical and biological properties, and stability. The toxicity of nanostructured materials could be reduced by chemical approaches such by surface treatment, functionalization, and composite formation. This review summarizes the sources of various nanostructured materials and their human exposure, biocompatibility in relation to potential toxicological effects, risk assessment, and safety evaluation on human and animal health as well as on the environment. PMID:18019130

  10. Advanced titania nanostructures and composites for lithium ion battery

    E-print Network

    Guo, John Zhanhu

    REVIEW Advanced titania nanostructures and composites for lithium ion battery Xin Su · QingLiu Wu to the increasing demand of energy and shifting to the renewable energy resources, lithium ion batteries (LIBs) have of the traditional energy sources [1], lithium ion batteries (LIBs) are being considered as the most promising green

  11. Energy transport and conversion in nanostructured materials

    NASA Astrophysics Data System (ADS)

    Wang, Robert Yue-Sheng

    The phononic and electronic density of states in quantum structures leads to transport characteristics that are distinctly different than those of bulk materials. For instance, much like a blackbody radiation spectrum, the phononic spectrum of bulk materials is broadband and continuous. In contrast, the phononic spectrum of a self-assembled monolayer (SAM) is a discrete spectrum of narrow bands. Experiments demonstrate that thermal transport through solid-SAM-solid junction is markedly different than thermal transport in a solid-solid junction. In particular, the thermal conductance of a solid-SAM-solid junction (˜10 1 MW/m2K) is much lower than the typical solid-solid junction (˜102 MW/m2K). In effect the discrete spectrum of the SAM creates a phonon filtering that reduces the overall heat transfer through it. This is analogous to how a blue filter can reduce the overall light intensity through it. Next, charge transport in thin films made of colloidal PbSe nanocrystals is discussed. These PbSe nanocrystals exhibit strong three-dimensional quantum confinement which results in an electronic structure similar to that of an atom. This electronic structure can be exploited to create a substantial Seebeck coefficient enhancement of several hundred muV/K relative to bulk PbSe. In addition, the carrier concentration of the nanocrystal thin films can be tuned by adjusting nanocrystal size and/or adjusting the nanocrystal chemical environment. For the last topic, an inexpensive and scalable technique to solution-process metal chalcogenides is presented. This technique uses hydrazine to create soluble precursors of solid metal chalcogenides. For example, a liquid-phase precursor for Bi2S3 can be made by mixing together solid-phase Bi2S3 with sulfur and hydrazine. This liquid precursor can then be spin-coated, printed, and/or stamped and then converted back into Bi2S3 by heating. Not only does this technique have promise for solution-processing of bulk materials, but with continued work, it has promise for solution-processing of nanostructured materials. For example, nanoparticles embedded in a matrix of Bi2S3 could be made by suspending nanoparticles in the liquid Bi2S3 precursor and then heating the mixture.

  12. Aerogel/polymer composite materials

    NASA Technical Reports Server (NTRS)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Roberson, Luke B. (Inventor); Clayton, LaNetra M. (Inventor)

    2010-01-01

    The invention provides new composite materials containing aerogels blended with thermoplastic polymer materials at a weight ratio of aerogel to thermoplastic polymer of less than 20:100. The composite materials have improved thermal insulation ability. The composite materials also have better flexibility and less brittleness at low temperatures than the parent thermoplastic polymer materials.

  13. Cylindrical nanostructured MoS2 directly grown on CNT composites for lithium-ion batteries.

    PubMed

    Yoo, HeeJoun; Tiwari, Anand P; Lee, JeongTaik; Kim, Doyoung; Park, Jong Hyeok; Lee, Hyoyoung

    2015-02-28

    Direct attachment of MoS2 to materials with carbonaceous architecture remains a major challenge because of non-intimate contact between the carbonaceous materials and active MoS2 material. In this study, we report a new unique synthetic method to produce a new type of hybrid nanostructure of MoS2-CNTs composites. We developed a novel strategy for the synthesis of cylindrical MoS2 directly grown on CNT composites without the use of any other additives, exhibiting superior electrochemical performance as the anode material of lithium-ion batteries via a microwave irradiation technique. We adopted a simple step-by-step method: coating sulfur on CNTs and then reaction with a Mo source to synthesize hybrid cylindrical nanostructures of the MoS2-CNT composite. X-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy analyses demonstrated that the as-synthesized MoS2-CNTs possessed a hybrid nanostructure, in which MoS2 sheets were well attached to the CNTs. The directly attached MoS2 sheets on the CNTs showed superior electrochemical performance as anode materials in a lithium-ion battery. PMID:25631660

  14. Nonequilibrium molecular dynamics for bulk materials and nanostructures

    E-print Network

    Dayal, Kaushik

    to the principle of material frame indifference, a cornerstone of nonlinear continuum mechanics. The methodNonequilibrium molecular dynamics for bulk materials and nanostructures Kaushik Dayal a,Ã, Richard with the corresponding experiments, are used to measure the material constants. In the simplest cases, these are elastic

  15. Composite electric contact materials

    NASA Astrophysics Data System (ADS)

    Senkara, J.; Kowalczyk, J.

    1985-12-01

    Two-phase composite materials, i.e., a high-melting component combined with a material exhibiting good electrical and thermal properties find a wide range of application for the manufacture of small- and medium-load relays and switches. Composite contacts can be used in air circuit-breakers (W-Ag, Ag-Ni), oil circuit-breakers (W-Cu, Mo-Cn), vacuum-type switches (W-CuSb, CuCr), and also switches operating in an atmosphere of SF sub 6 (W-Cu). Present-day trends aimed at increasing operating reliability and extending the service life of electrical equipment are finding their expression in efforts being made to modify the classical composites with a veiw to imparting new properties to them by suitably changing their composition and structure. These trends are also aimed at reducing the consumption of noble metals and of strategically important ones. Modern materials engineering and metallurgical technologies are being used, including isostatic sintering or explosive forming. Owing to the high activity of the constituents, all processes are conducted under high vacuum or in pure reducing atmospheres.

  16. Nanoporous and Nanostructured Materials for Energy Storage and Sensor Applications

    NASA Astrophysics Data System (ADS)

    Vu, Anh D.

    The major objective of this work is to design nanostructured and nanoporous materials targeting the special needs of the energy storage and sensing fields. Nanostructured and nanoporous materials are increasingly finding applications in many fields, including electrical energy storage and explosive sensing. The advancement of energy storage devices is important to the development of three fields that have strong effects on human society: renewable energy, transportation, and portable devices. More sensitive explosive sensors will help to prevent terrorism activities and boost national security. Hierarchically porous LiFePO4 (LFP)/C composites were prepared using a surfactant and colloidal crystals as dual templates. The surfactant serves as the template for mesopores and polymeric colloidal spheres serve as the template for macropores. The confinement of the surfactant-LFP-carbon precursor in the colloidal templates is crucial to suppress the fast crystallization of LFP and helps to maintain the ordered structure. The obtained composites with high surface areas and ordered porous structure showed excellent rate performance when used as cathode materials for LIBs, which will allow them to be used as a power source for EVs and HEVs. The synthesis of LiFePO 4 in three dimensionally confined spaces within the colloidal template resulted in the formation of spherical particles. Densely packed LiFePO 4 spheres in a carbon matrix were obtained by spin-casting the LFP-carbon precursor on a quartz substrate and then pyrolyzing it. The product showed high capacity and could be charged /discharged with very little capacity fading over many cycles. Three-dimensionally ordered mesoporous carbons were prepared from nano-sized silica sphere colloidal crystal templates. These materials with very high surface areas and ordered porous structure showed high capacitance and excellent rate capability when used as electrodes for supercapacitors. Mesoporous silica thin films of different morphologies, including disordered (wormlike), 2D-hexagonal, 3D-hexagonal, and cubic structure, were prepared. The films were then doped or bridged with fluorescence compounds and used as sensors for nitroaromatic compounds. The sensor performance depended on both the film structure and the mode of fluorophore attachment. The best films showed high quenching rates and were stable during long time storage. The films can potentially be incorporated in portable sensing devices.

  17. Advanced composite materials and processes

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M.

    1991-01-01

    Composites are generally defined as two or more individual materials, which, when combined into a single material system, results in improved physical and/or mechanical properties. The freedom of choice of the starting components for composites allows the generation of materials that can be specifically tailored to meet a variety of applications. Advanced composites are described as a combination of high strength fibers and high performance polymer matrix materials. These advanced materials are required to permit future aircraft and spacecraft to perform in extended environments. Advanced composite precursor materials, processes for conversion of these materials to structures, and selected applications for composites are reviewed.

  18. Li ion battery materials with core-shell nanostructures

    Microsoft Academic Search

    Liwei Su; Yu Jing; Zhen Zhou

    2011-01-01

    Nanomaterials have some disadvantages in application as Li ion battery materials, such as low density, poor electronic conductivity and high risk of surface side reactions. In recent years, materials with core-shell nanostructures, which was initially a common concept in semiconductors, have been introduced to the field of Li ion batteries in order to overcome the disadvantages of nanomaterials, and increase

  19. Nanostructured Thermoelectric Materials: From Superlattices to Nanocomposites Ronggui Yang1

    E-print Network

    Chen, Gang

    Nanostructured Thermoelectric Materials: From Superlattices to Nanocomposites Ronggui Yang1 conductivity led to a large increase in the thermoelectric figure of merit in several superlattice systems. Materials with a large thermoelectric figure of merit can be used to develop efficient solid-state devices

  20. Applications of Ultrasound to the Synthesis of Nanostructured Materials

    E-print Network

    Suslick, Kenneth S.

    Applications of Ultrasound to the Synthesis of Nanostructured Materials By Jin Ho Bang and Kenneth of ultrasound for materials synthesis has been extensively examined over many years, and is now positioned successful ultrasound-assisted synthetic methods (sonochemistry and ultrasonic spray pyrolysis

  1. Preparation and properties on hollow nano-structured smoke material

    NASA Astrophysics Data System (ADS)

    Liu, Xiang-cui; Dai, Meng-yan; Fang, Guo-feng; Shi, Wei-dong; Cheng, Xiang; Liu, Hai-feng; Zhang, Tong

    2013-09-01

    In recent years, the weapon systems of laser guidance and infrared (IR) imaging guidance have been widely used in modern warfare because of their high precision and strong anti-interference. Notwithstanding, military smoke, as a rapid and effective passive jamming means, can effectively counteract the attack of enemy precision-guided weapons by scattering and absorbability. Conventional smoke has good attenuation capability only to visible light (0.4-0.76 ?m), but hardly any effect to other electromagnetic wave band. The weapon systems of laser guidance and IR imaging guidance usually work in broad band, including near IR (1-3 ?m), middle IR (3-5 ?m), far IR (8-14 ?m), and so on. Accordingly, exploiting and using new efficient obscurant materials, which is one of the important factors that develop smoke technology, have become a focus and attracted more interests around the world. Then nano-structured materials that are developing very quickly have turned into our new choice. Hollow nano-structured materials (HNSM) have many special properties because of their nano-size wall-thickness and sub-micron grain-size. After a lot of HNSM were synthesized in this paper, their physical and chemical properties, including grain size, phase composition, microstructure, optical properties and resistivity were tested and analysed. Then the experimental results of the optical properties showed that HNSM exhibit excellent wave-absorbing ability in ultraviolet, visible and infrared regions. On the basis of the physicochemmical properties, HNSM are firstly applied in smoke technology field. And the obscuration performance of HNSM smoke was tested in smoke chamber. The testing waveband included 1.06?m and 10.6?m laser, 3-5?m and 8-14?m IR radiation. Then the main parameters were obtained, including the attenuation rate, the transmission rate, the mass extinction coefficient, the efficiency obscuring time, and the sedimentation rate, etc. The main parameters of HNSM smoke were contrasted in detail with graphite powder smoke agent. The results showed that HNSM smoke possesses better obscuration capability compared with the smoke performance of conventional materials (such as HC, RP, oil, carbon black, and graphite powder). Therefore, they are new smoke obscurant materials which can effectively interfere with broadband electromagnetic radiation, including 1.06 ?m and 10.6 ?m laser, 3-5 ?m and 8-14 ?m IR waveband.

  2. New composite thermoelectric materials for energy harvesting applications

    Microsoft Academic Search

    M. S. Dresselhaus; G. Chen; Z. F. Ren; G. Dresselhaus; A. Henry; J.-P. Fleurial

    2009-01-01

    The concept of using nanostructured composite materials to enhance the dimensionless thermoelectric figure of merit ZT relative\\u000a to that for their counterpart homogeneous alloyed bulk crystalline materials of similar chemical composition is presented\\u000a in general terms. Specific applications are made to the Si-Ge and Bi2-?xSbxTe3 systems for use in high-temperature power generation and cooling applications. The scientific advantages of the

  3. Nanostructure materials for biosensing and bioimaging applications

    NASA Astrophysics Data System (ADS)

    Law, Wing Cheung

    In the first part of the thesis our work on a surface plasmon resonance (SPR) biosensor will be presented. It will begin with understanding the working principle of SPR sensing technology and the basic concept of SPR biosensing. In SPR technology, there are different coupling schemes to excite surface plasmons such as prism coupler, grating coupler and waveguide coupler. Our setup will be based on the attenuated total reflection (ATR) prism coupling configuration. A gold sensing film is attached to one face of the prism. The samples are flowing over the gold surface and the light source is directed to the prism side. The reflected beam containing SPR information is collected and analyzed. SPR biosensors have become powerful tools in biological and chemical sensing application because of their capability of real-time monitoring and label-free sensing. Quantitative measurements such as the binding kinetics and the binding affinity between two biomolecules can be readily calculated from the SPR sensorgram. In our design, SPR phase will be monitored using photoelastic modulation (PEM) technique. The PEM is used to produce a modulation signal so that the phase quantity can be extracted by measuring the relative amplitudes of the harmonic signals. Since this system contains no moving component and only single beam and single detector are used, precise component alignment, which may be troublesome in making the setup compact and robust, can be eliminated. In order to demonstrate the operation of the proposed approach, two experiments were performed. The first one was to measure the refractive index change caused by varying the concentration of glycerin-water mixtures. The second one was to monitor the binding reactions between biotin and streptavidin--BSA complex at the sensor surface. Recently, the use of metallic nanoparticle on SPR platform has received great attention due to the capability of sensitivity enhancement. Although the mechanism of the enhancement is still not fully understand, three possible factors are concluded after systematic researches: (i) an increase of the absolute mass in each binding event, (ii) an increase in the bulk refractive index of the analyte, and (iii) coupling between the localized surface plasmon resonance (LSPR) of metallic nanoparticles and surface plasmon resonance (SPR) of the sensing film. Indeed, the role of plasmonic coupling in sensitivity enhancement is still an open question. In order to obtain a better understanding of this phenomenon, at the end of part I, extended studies were performed to investigate how the LSPR properties of metallic nanoparticle labels correlate with the enhancement factor. For this purpose, gold nanorods (Au-NRs) were chosen as the amplification labels because of the easy tunability of LSPR peak of Au-NR. After reading the "Result and Discussion" section, the readers will have better understanding of "plasmonic coupling" between the sensing film and the metallic labels with suitable operating laser source. In the second part of the thesis, the bioimaging part, the application of nanostructure materials in live cancer cell imaging and small animal imaging were demonstrated. There are different types of imaging technique available in laboratories and clinics: optical imaging, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), thermography and ultrasound imaging. Although such imaging techniques have been well developed and used over a decade, improving the sensitivity, enhancing the contrast, decreasing the acquisition time and reducing the toxicity of the contrast agent are highly desirable. For optical imaging, the scientists discovered that the use of near infrared fluorescence materials can assist the surgeon to locate the tumor, the nerve and the lymph node more accurately. For CT scan, the use of Au-NR as the contrast agent can improve the sensitivity. Iron oxide nanoparticle or gadolinium ion containing nanoparticle can greatly enhance the contrast of MRI. On the one hand, concrete effort

  4. Compositional ordering and stability in nanostructured, bulk thermoelectric alloys.

    SciTech Connect

    Hekmaty, Michelle A.; Faleev, S.; Medlin, Douglas L.; Leonard, F.; Lensch-Falk, J.; Sharma, Peter Anand; Sugar, J. D.

    2009-09-01

    Thermoelectric materials have many applications in the conversion of thermal energy to electrical power and in solid-state cooling. One route to improving thermoelectric energy conversion efficiency in bulk material is to embed nanoscale inclusions. This report summarize key results from a recently completed LDRD project exploring the science underpinning the formation and stability of nanostructures in bulk thermoelectric and the quantitative relationships between such structures and thermoelectric properties.

  5. Synthesis of nanostructured materials in inverse miniemulsions and their applications

    NASA Astrophysics Data System (ADS)

    Cao, Zhihai; Ziener, Ulrich

    2013-10-01

    Polymeric nanogels, inorganic nanoparticles, and organic-inorganic hybrid nanoparticles can be prepared via the inverse miniemulsion technique. Hydrophilic functional cargos, such as proteins, DNA, and macromolecular fluoresceins, may be conveniently encapsulated in these nanostructured materials. In this review, the progress of inverse miniemulsions since 2000 is summarized on the basis of the types of reactions carried out in inverse miniemulsions, including conventional free radical polymerization, controlled/living radical polymerization, polycondensation, polyaddition, anionic polymerization, catalytic oxidation reaction, sol-gel process, and precipitation reaction of inorganic precursors. In addition, the applications of the nanostructured materials synthesized in inverse miniemulsions are also reviewed.

  6. Synthesis of nanostructured materials in inverse miniemulsions and their applications.

    PubMed

    Cao, Zhihai; Ziener, Ulrich

    2013-11-01

    Polymeric nanogels, inorganic nanoparticles, and organic-inorganic hybrid nanoparticles can be prepared via the inverse miniemulsion technique. Hydrophilic functional cargos, such as proteins, DNA, and macromolecular fluoresceins, may be conveniently encapsulated in these nanostructured materials. In this review, the progress of inverse miniemulsions since 2000 is summarized on the basis of the types of reactions carried out in inverse miniemulsions, including conventional free radical polymerization, controlled/living radical polymerization, polycondensation, polyaddition, anionic polymerization, catalytic oxidation reaction, sol-gel process, and precipitation reaction of inorganic precursors. In addition, the applications of the nanostructured materials synthesized in inverse miniemulsions are also reviewed. PMID:24056795

  7. Hierarchical oxide-based composite nanostructures for energy, environmental, and sensing applications

    NASA Astrophysics Data System (ADS)

    Gao, Pu-Xian; Shimpi, Paresh; Cai, Wenjie; Gao, Haiyong; Jian, Dunliang; Wrobel, Gregory

    2011-02-01

    Self-assembled composite nanostructures integrate various basic nano-elements such as nanoparticles, nanofilms and nanowires toward realizing multifunctional characteristics, which promises an important route with potentially high reward for the fast evolving nanoscience and nanotechnology. A broad array of hierarchical metal oxide based nanostructures have been designed and fabricated in our research group, involving semiconductor metal oxides, ternary functional oxides such as perovskites and spinels and quaternary dielectric hydroxyl metal oxides with diverse applications in efficient energy harvesting/saving/utilization, environmental protection/control, chemical sensing and thus impacting major grand challenges in the area of materials and nanotechnology. Two of our latest research activities have been highlighted specifically in semiconductor oxide alloy nanowires and metal oxide/perovskite composite nanowires, which could impact the application sectors in ultraviolet/blue lighting, visible solar absorption, vehicle and industry emission control, chemical sensing and control for vehicle combustors and power plants.

  8. Potential applications of nanostructured materials in nuclear waste management.

    SciTech Connect

    Braterman, Paul S. (The University of North Texas, Denton, TX); Phol, Phillip Isabio; Xu, Zhi-Ping (The University of North Texas, Denton, TX); Brinker, C. Jeffrey; Yang, Yi (University of New Mexico, Albuquerque, NM); Bryan, Charles R.; Yu, Kui; Xu, Huifang (University of New Mexico, Albuquerque, NM); Wang, Yifeng; Gao, Huizhen

    2003-09-01

    This report summarizes the results obtained from a Laboratory Directed Research & Development (LDRD) project entitled 'Investigation of Potential Applications of Self-Assembled Nanostructured Materials in Nuclear Waste Management'. The objectives of this project are to (1) provide a mechanistic understanding of the control of nanometer-scale structures on the ion sorption capability of materials and (2) develop appropriate engineering approaches to improving material properties based on such an understanding.

  9. Nanostructured thermoelectric materials and optical method for thermal conductivity measurement

    NASA Astrophysics Data System (ADS)

    Zamanipour, Zahra

    A good thermoelectric material has large electrical conductivity, large Seebeck coefficient, and small thermal conductivity. Among the different techniques to achieve small thermal conductivity is the nanostructuring method. In a nanostructured material the thermal conductivity decreases due to the increased interfacial scattering of phonons. In most thermoelectric materials, due to the larger mean free path of phonons compared with electrons, the effect of interfaces on phonon scatterings is more than on carrier scattering. Therefore, reduction of the thermal conductivity becomes possible with almost no or small change in the electrical conductivity via nanostructuring. The materials that have shown large power factor but have small efficiency due to their large thermal conductivity are good candidates for nanostructuring. For high temperature applications, several transition metal silicides have shown high power factor while they have large thermal conductivity. While silicides have been investigated in crystalline and polycrystalline form in the past, their nanostructuring had not been pursued extensively at the time that this research started. In this PhD dissertation, we have developed several nanostructured materials based on transition metal silicides. In the path to develop high temperature thermoelectric materials, synthesis, structural characterizations, thermoelectric properties measurements, and analysis of the nanostructured bulk Si1-xGex, Higher Manganese Silicide (HMS), Si0.8Ge0.2 structures with CrSi2 nanocrystallite inclusions, and nanocomposites of SiGe-FeSi2 were completed. The synthesis process parameters including powder processing and sintering parameters were derived for each material system. Model calculations for electron and phonon transport were performed in detail to explain the measured data and direct the experiments. Boron precipitation effect on thermoelectric properties of Si0.8Ge0.2 was also studied by analyzing the experimental data and through theoretical calculations. At the device level, in order to find the optimum metal contact for HMS, an extensive study was performed to find the best electrical contact for HMS thermoelectric devices. Along with thermoelectric material development, a novel ultrafast optical characterization method for thermal properties measurement and ultrafast carrier dynamics study was also developed. The designed optical system is a new pump-probe arrangement to perform both thermal properties measurement and ultrafast carrier dynamics study in one set up. The existing radial heat flow analysis for thermal properties measurement was extended to three-dimensional heat flow, which is applicable for distinguishing the xyz thermal conductivity of the anisotropic material.

  10. Formation of nanostructured MnO/Co/solid-electrolyte interphase ternary composites as a durable anode material for lithium-ion batteries.

    PubMed

    Dang, Feng; Oaki, Yuya; Kokubu, Takao; Hosono, Eiji; Zhou, Haoshen; Imai, Hiroaki

    2013-04-01

    Nanoporous MnO frameworks with highly dispersed Co nanoparticles were produced from MnCO3 precursors prepared in a gel matrix. The MnO frameworks that contain 20 mol% Co exhibited excellent cycle performance as an anode material for Li-ion batteries. The solid-electrolyte interphase (SEI) formed in the frameworks through the electrochemical reaction mediates the active materials, such as MnO, Mn, and Li2O, during the conversion reaction in the charge-discharge cycle. The Co nanoparticles and SEI provide the electron and Li-ion conductive networks, respectively. The ternary nanocomposites of the MnO framework, metallic Co nanoparticles, and embedded SEI are categorized as durable anode materials for Li-ion batteries. PMID:23401355

  11. Assembling and properties of the polymer-particle nanostructured materials

    Microsoft Academic Search

    Roman Sheparovych

    2010-01-01

    Complementary properties of the soft and hard matter explain its common encounter in many natural and manmade applications. A combination of flexible organic macromolecules and hard mineral clusters results in new materials far advantageous than its constituents alone. In this work we study assembling of colloidal nanocrystals and polymers into complex nanostructures. Magnetism, surface wettability and adhesion comprise properties of

  12. Carbon nanostructures as sorbent materials in analytical processes

    Microsoft Academic Search

    M. Valcárcel; S. Cárdenas; B. M. Simonet; Y. Moliner-Martínez; R. Lucena

    2008-01-01

    Over time, new materials have been used and incorporated in a wide variety of analytical processes. This century, technology has produced novel nanomaterials with unique properties whose use has increased in analytical sciences. Carbon nanostructures are among these new nanomaterials. This overview reports on the use of carbon nanomaterials, mainly fullerenes and carbon nanotubes, as sorbents in the analytical process.

  13. Current status of nanostructured tungsten-based materials development

    NASA Astrophysics Data System (ADS)

    Kurishita, H.; Matsuo, S.; Arakawa, H.; Sakamoto, T.; Kobayashi, S.; Nakai, K.; Okano, H.; Watanabe, H.; Yoshida, N.; Torikai, Y.; Hatano, Y.; Takida, T.; Kato, M.; Ikegaya, A.; Ueda, Y.; Hatakeyama, M.; Shikama, T.

    2014-04-01

    Nanostructured tungsten (W)-based materials offer many advantages for use as plasma facing materials and components exposed to heavy thermal loads combined with irradiation with high-energy neutron and low-energy ion. This paper first presents the recent progress in nanostructured toughened, fine grained, recrystallized W materials. Thermal desorption spectrometry apparatus equipped with an ion gun has been installed in the radiation controlled area in our Center at Tohoku University to systematically investigate the effects of displacement damage due to high-energy neutron irradiation on hydrogen isotope retention in connection with the nano- or micro-structures in W-based materials. In this paper, the effects of high-energy heavy ion irradiation on deuterium retention in W with different microstructures are described as a preliminary work with the prospective view of neutron irradiation effects.

  14. Nanostructured Materials Developed for Solar Cells

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila G.; Castro, Stephanie L.; Raffaelle, Ryne P.; Fahey, Stephen D.; Gennett, Thomas; Tin, Padetha

    2004-01-01

    There has been considerable investigation recently regarding the potential for the use of nanomaterials and nanostructures to increase the efficiency of photovoltaic devices. Efforts at the NASA Glenn Research Center have involved the development and use of quantum dots and carbon nanotubes to enhance inorganic and organic cell efficiencies. Theoretical results have shown that a photovoltaic device with a single intermediate band of states resulting from the introduction of quantum dots offers a potential efficiency of 63.2 percent. A recent publication extended the intermediate band theory to two intermediate bands and calculated a limiting efficiency of 71.7 percent. The enhanced efficiency results from converting photons of energy less than the band gap of the cell by an intermediate band. The intermediate band provides a mechanism for low-energy photons to excite carriers across the energy gap by a two-step process.

  15. Utilising thermoporometry to obtain new insights into nanostructured materials

    Microsoft Academic Search

    Joakim Riikonen; Jarno Salonen; Vesa-Pekka Lehto

    Thermoporometry is a relatively new method of characterising porous properties of nanostructured materials based on observation\\u000a of solid–liquid phase transitions of materials confined in pores. It provides several advantages over the conventional characterisation\\u000a methods, mercury porosimetry and gas sorption. The advantages include possibility of using short measurement times, non-toxic\\u000a chemicals and wet samples. In addition, complicated sample preparation and specialised

  16. Nanostructured Al-Based Metal Matrix Composite Coating Production by Pulsed Gas Dynamic Spraying Process

    NASA Astrophysics Data System (ADS)

    Yandouzi, M.; Bu, H.; Brochu, M.; Jodoin, B.

    2012-06-01

    The advantage of combining cryomilling and pulsed gas dynamic spraying (PGDS) processes in order to produce a nanostructured, dense and wear resistant coating was demonstrated. Cryomilling was successfully employed to synthesize particulate B4C reinforced Al matrix nanocomposite feedstock powders, while the PGDS process shows the ability of preserving the microstructure of the starting material. In this study, nanocrystalline and conventional Al5356 + 20%B4C composite as well as the unreinforced Al5356 alloy feedstock powders were used. The influence of the nature of the feedstock material on the microstructure and mechanical properties of the coatings was studied. The PGDS process provides an opportunity to preserve the phase of the starting material, to produce hard and dense coatings with good cohesion between deformed particles and good adhesion to the substrate. High dry sliding wear resistance was observed when cryomilled composite material was used.

  17. Nanostructured electrocatalyst for fuel cells : silica templated synthesis of Pt/C composites.

    SciTech Connect

    Stechel, Ellen Beth; Switzer, Elise E.; Fujimoto, Cy H.; Atanassov, Plamen Borissov; Cornelius, Christopher James; Hibbs, Michael R.

    2007-09-01

    Platinum-based electrocatalysts are currently required for state-of-the-art fuel cells and represent a significant portion of the overall fuel cell cost. If fuel cell technology is to become competitive with other energy conversion technologies, improve the utilization of precious metal catalysts is essential. A primary focus of this work is on creating enhanced nanostructured materials which improve precious-metal utilization. The goal is to engineer superior electrocatalytic materials through the synthesis, development and investigation of novel templated open frame structures synthesized in an aerosol-based approach. Bulk templating methods for both Pt/C and Pt-Ru composites are evaluated in this study and are found to be limited due to the fact that the nanostructure is not maintained throughout the entire sample. Therefore, an accurate examination of structural effects was previously impossible. An aerosol-based templating method of synthesizing nanostructured Pt-Ru electrocatalysts has been developed wherein the effects of structure can be related to electrocatalytic performance. The aerosol-based templating method developed in this work is extremely versatile as it can be conveniently modified to synthesize alternative materials for other systems. The synthesis method was able to be extended to nanostructured Pt-Sn for ethanol oxidation in alkaline media. Nanostructured Pt-Sn electrocatalysts were evaluated in a unique approach tailored to electrocatalytic studies in alkaline media. At low temperatures, nanostructured Pt-Sn electrocatalysts were found to have significantly higher ethanol oxidation activity than a comparable nanostructured Pt catalyst. At higher temperatures, the oxygen-containing species contribution likely provided by Sn is insignificant due to a more oxidized Pt surface. The importance of the surface coverage of oxygen-containing species in the reaction mechanism is established in these studies. The investigations in this work present original studies of anion exchange ionomers as entrapment materials for rotating disc electrode (RDE) studies in alkaline media. Their significance is linked to the development of membrane electrode assemblies (MEAs) with the same ionomer for a KOH-free alkaline fuel cell (AFC).

  18. Heat transport by phonons in crystalline materials and nanostructures

    NASA Astrophysics Data System (ADS)

    Koh, Yee Kan

    This dissertation presents experimental studies of heat transport by phonons in crystalline materials and nanostructures, and across solid-solid interfaces. Particularly, this dissertation emphasizes advancing understanding of the mean-free-paths (i.e., the distance phonons propagate without being scattered) of acoustic phonons, which are the dominant heat carriers in most crystalline semiconductor nanostructures. Two primary tools for the studies presented in this dissertation are time-domain thermoreflectance (TDTR) for measurements of thermal conductivity of nanostructures and thermal conductance of interfaces; and frequency-domain thermoreflectance (FDTR), which I developed as a direct probe of the mean-free-paths of dominant heat-carrying phonons in crystalline solids. The foundation of FDTR is the dependence of the apparent thermal conductivity on the frequency of periodic heat sources. I find that the thermal conductivity of semiconductor alloys (InGaP, InGaAs, and SiGe) measured by TDTR depends on the modulation frequency, 0.1 ? f ? 10 MHz, used in TDTR measurements. Reduction in the thermal conductivity of the semiconductor alloys at high f compares well to the reduction in the thermal conductivity of epitaxial thin films, indicating that frequency dependence and thickness dependence of thermal conductivity are fundamentally equivalent. I developed the frequency dependence of thermal conductivity into a convenient probe of phonon mean-free-paths, a technique which I call frequency-domain thermoreflectance (FDTR). In FDTR, I monitor the changes in the intensity of the reflected probe beam as a function of the modulation frequency. To facilitate the analysis of FDTR measurements, I developed a nonlocal theory for heat conduction by phonons at high heating frequencies. Calculations of the nonlocal theory confirm my experimental findings that phonons with mean-free-paths longer than two times the penetration depth do not contribute to the apparent thermal conductivity. I employed FDTR to study the mean-free-paths of acoustic phonons in Si1-xGex. I experimentally demonstrate that 40% of heat is carried in Si1-xGe x alloys by phonons with mean-free-path 0.5 ? ? ? 5 mum, and phonons with > 2 mum do not contribute to the thermal conductivity of Si. I employed TDTR and frequency-dependent TDTR to study scattering of long- and medium-wavelength phonons in two important thermoelectric materials embedded with nanoscale precipitates. I find that the through-thickness lattice thermal conductivity of (PbTe)1-x/(PbSe)x nanodot superlattices (NDSLs) approaches the thermal conductivity of bulk homogenous PbTe1-x Sex alloys with the same average composition. On the other hand, I find that 3% of ErAs nanoparticles embedded in InGaAs is sufficient to scatter most of the phonons in InGaAs that have intermediate mean-free-paths, and thus reduces the thermal conductivity of InGaAs below the alloy limit. I find that scattering by nanoparticles approach the geometrical limit and can be readily accounted for by an additional boundary scattering which depends on the concentration of nanoparticles. Finally, I studied the thermal conductance of Au/Ti/Graphene/SiO 2 interfaces by TDTR. I find that heat transport across the interface is dominated by phonons. Even though graphene is only one atomic layer thick, graphene interfaces should be treated as two discrete interfaces instead of one diffuse interface in thermal analysis, suggesting that direct transmission of phonons from Au to SiO2 is negligible. My study is important for thermal management of graphene devices.

  19. Probing Compositional Variation within Hybrid Nanostructures

    SciTech Connect

    Yuhas, Benjamin D.; Habas, Susan E.; Fakra, Sirine C.; Mokari, Taleb

    2010-06-22

    We present a detailed analysis of the structural and magnetic properties of solution-grown PtCo-CdS hybrid structures in comparison to similar free-standing PtCo alloy nanoparticles. X-ray absorption spectroscopy is utilized as a sensitive probe for identifying subtle differences in the structure of the hybrid materials. We found that the growth of bimetallic tips on a CdS nanorod substrate leads to a more complex nanoparticle structure composed of a PtCo alloy core and thin CoO shell. The core-shell architecture is an unexpected consequence of the different nanoparticle growth mechanism on the nanorod tip, as compared to free growth in solution. Magnetic measurements indicate that the PtCo-CdS hybrid structures are superparamagnetic despite the presence of a CoO shell. The use of X-ray spectroscopic techniques to detect minute differences in atomic structure and bonding in complex nanosystems makes it possible to better understand and predict catalytic or magnetic properties for nanoscale bimetallic hybrid materials.

  20. Nanostructured interpenetrating phase composites by non-equilibrium compaction of in situ synthesized powders

    Microsoft Academic Search

    O. I. Lomovsky; D. V. Dudina; M. A. Korchagin; V. I. Mali; Y.-S. Kwon; J.-S. Kim

    2005-01-01

    We suggest using two-stage processing of metal-ceramic interpenetrating phase composites (IPCs) including preparation of composite powder precursors by reaction in a metal matrix and subsequent compaction of as-synthesized nanostructured powders. The appropriate choice of compaction technique allows obtaining dense nanostructured bulk IPCs. Bulk nanostructured TiB2-Cu IPCs were fabricated by spark plasma sintering (SPS) and shock wave compaction of powder precursors.

  1. Mechanics of composite materials

    Microsoft Academic Search

    G. J. Dvorak; N. Laws

    1988-01-01

    This book contains the following papers: crack growth resistance of TiBâ particulate\\/SiC matrix composite; constitutive relations of flexible composites under elastic deformation; determination of two kinds of composite plasticity: inclusions plastic vs. matrix plastic; 3-D analysis of transient interlaminar thermal stress of laminated composites; effect of seawater on the fracture toughness of pultruded rods; evaluation of new failure criterion for

  2. Composite WO3/TiO2 nanostructures for high electrochromic activity.

    PubMed

    Reyes-Gil, Karla R; Stephens, Zachary D; Stavila, Vitalie; Robinson, David B

    2015-02-01

    A composite material consisting of TiO2 nanotubes (NT) with WO3 electrodeposited on its surface has been fabricated, detached from its Ti substrate, and attached to a fluorine-doped tin oxide (FTO) film on glass for application to electrochromic (EC) reactions. Several adhesion layers were tested, finding that a paste of TiO2 made from commercially available TiO2 nanoparticles creates an interface for the TiO2 NT film to attach to the FTO glass, which is conductive and does not cause solution-phase ions in an electrolyte to bind irreversibly with the material. The effect of NT length and WO3 concentration on the EC performance were studied. The composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast, and longer memory time compared with the pure WO3 and TiO2 materials. PMID:25562778

  3. Composite materials: science and engineering

    SciTech Connect

    Chawla, K.K.

    1987-01-01

    The properties and applications of composite materials are examined in an introductory textbook for senior and graduate engineering students. Chapters are devoted to glass, B, C, organic, ceramic, and metallic fibers; polymer, ceramic, and metallic matrix materials; polymer-matrix composites; MMCs; ceramic-matrix composites; CFRPs; and multifilament superconducting composites. Consideration is given to the micromechanics of composites, macromechanical characteristics, strength, fracture, fatigue, and design problems. Diagrams, graphs, photographs, and tables of numerical data are included, and a set of problems is given for each chapter.

  4. Composite material heat pipe radiator

    Microsoft Academic Search

    Nelson J. Gernert; David B. Sarraf; Richard J. Guenther

    1996-01-01

    Organic matrix composite material is recognized for its significant strength to weight ratio when compared to metal and consequently was investigated for reducing the mass of heat pipes for future space missions. The particular heat pipe that was constructed and tested was made from an organic matrix composite material applied to a linear of titanium tubing spun to foil thickness

  5. Sitall-base composite materials

    Microsoft Academic Search

    I. I. Beloborodov; A. I. Yuga; N. D. Nazarenko; L. F. Kolesnichenko; N. I. Vlasko

    1976-01-01

    1.The feasibility is demonstrated of producing Sitall-base porous skeletons.2.Impregnation of a porous skeleton with a suspension of PTFE and graphite enables a composite material to be obtained possessing excellent antifriction properties.3.The presence of a metallic filler in such a composite material increases its load-carrying capacity.

  6. Equivalent-Continuum Modeling of Nano-Structured Materials

    Microsoft Academic Search

    Gregory M. Odegard; Thomas S. Gates; Lee M. Nicholson

    2001-01-01

    A method has been developed for modeling structure-property relationships of nano-stmcturedmaterials. This method serves as a link between computational chemistry and solid mechanicsby substituting discrete molecular structures with an equivalent-continuum model. It has beenshown that this substitution may be accomplished by equating the vibrational potential energy ofa nano-structured material with the strain energy of representative truss and continuum models.As an

  7. Towards highly sensitive strain sensing based on nanostructured materials

    Microsoft Academic Search

    Dzung Viet Dao; Tung Thanh Bui; Koichi Nakamura; Van Thanh Dau; Takeo Yamada; Kenji Hata; Susumu Sugiyama

    2010-01-01

    This paper presents our recent theoretical and experimental study of piezo-effects in nanostructured materials for highly sensitive, high resolution mechanical sensors. The piezo-effects presented here include the piezoresistive effect in a silicon nanowire (SiNW) and single wall carbon nanotube (SWCNT) thin film, as well as the piezo-optic effect in a Si photonic crystal (PhC) nanocavity. Firstly, the electronic energy band

  8. Thermoelectric energy conversion using nanostructured materials

    E-print Network

    Chen, Gang

    High performance thermoelectric materials in a wide range of temperatures are essential to broaden the application spectrum of thermoelectric devices. This paper presents experiments on the power and efficiency characteristics ...

  9. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1981-01-01

    The composite aircraft program component (CAPCOMP) is a graduate level project conducted in parallel with a composite structures program. The composite aircraft program glider (CAPGLIDE) is an undergraduate demonstration project which has as its objectives the design, fabrication, and testing of a foot launched ultralight glider using composite structures. The objective of the computer aided design (COMPAD) portion of the composites project is to provide computer tools for the analysis and design of composite structures. The major thrust of COMPAD is in the finite element area with effort directed at implementing finite element analysis capabilities and developing interactive graphics preprocessing and postprocessing capabilities. The criteria for selecting research projects to be conducted under the innovative and supporting research (INSURE) program are described.

  10. Composite Materials: Sticks and Glue

    NSDL National Science Digital Library

    Stoebe, Thomas G.

    This learning activity will provide a good example of "the effect on strength and stiffness of a material when it is manufactured as a composite." Popsicle sticks will be used to demonstrate the difference between singular materials and composite materials. Students will be able to see the added benefits of using composite materials. This activity would be suitable for elementary school through college level students, with each grade level gaining different educational benefits. The lesson should take from 5 to 20 minutes, depending on grade level. This document will serve as a framework for instructors and may be downloaded in PDF format.

  11. Composite structural materials

    NASA Technical Reports Server (NTRS)

    Loewy, Robert G.; Wiberley, Stephen E.

    1988-01-01

    A decade long program to develop critical advanced composite technology in the areas of physical properties, structural concept and analysis, manufacturing, reliability, and life predictions is reviewed. Specific goals are discussed. The status of the chemical vapor deposition effects on carbon fiber properties; inelastic deformation of metal matrix laminates; fatigue damage in fibrous MMC laminates; delamination fracture toughness in thermoplastic matrix composites; and numerical analysis of composite micromechanical behavior are presented.

  12. Fabrication and characterization of nanostructured III-V thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Novotny, Clint; Sharifi, Fred

    2013-09-01

    Approximately two thirds of all fossil fuel used is lost as heat. Thermoelectric materials, which convert heat into electrical energy, may provide a solution to partially recover some of this lost energy. To date, most commercial thermoelectric materials are too inefficient to be a viable option for most waste heat applications. This research proposes to investigate the fabrication and characterization of nanostructured III-V semiconductor thermoelectric materials with the goal of increasing the performance of existing technology. In order to improve thermoelectric material efficiency, either the lattice thermal conductivity must be lowered or the thermoelectric power factor must be increased. This research will focus on the latter by modifying the density of states of the semiconductor material and studying the effect of quantum confinement on the material's thermoelectric properties. Using focused ion beam milling, nanostructured cantilevers are fabricated from single crystal wafers. An all around gate dielectric and electrode are deposited to create a depletion region along the outer core of the cantilever, thus creating an inner conductive core. The Seebeck coefficient can then be measured as a function of confinement by varying the gate voltage. This technique can be applied to various material systems to investigate the effects of confinement on their thermoelectric properties.

  13. Nanostructured metal-nanocarbon composites: Production and studying of structural and mechanical properties

    NASA Astrophysics Data System (ADS)

    Prokhorov, V. M.; Blank, V. D.; Bagramov, R. H.; Perfilov, S. A.; Pivovarov, G. I.

    2013-12-01

    In the past two decades, the design methods of nanostructured composites with hierarchical structure consisting of metal-matrix composed nanoparticles and various binding between them - so-called metal-matrix nanocomposites (MNCs) - have intensively develop. At manufacturing MNCs, numerous combinations of matrixes and additives are used. Fabrication methods are an important part of the design process for MNCs, as well. It is anticipated that bulk materials with nanocarbon constituents could have high mechanical properties due to peculiarities of the nanostructure and special properties of its nano-building blocks, such as nanodiamond, fullerenes and nanotubes. In this work we report the design and properties of bulk MNCs containing nanocarbon in metal nanocrystals, and nanocarbon also serves as a binding medium filling interfaces. These works were conducted within 2007÷2012 in TISNCM. We manufactured MNCs by mechanical alloying (high energy ball milling) of the parent materials, such as metals (Fe, Steels, Al, Al-alloys, Cu, W) and refractory carbides (WC, ZrC, TaC, TiC), with nanocarbon followed by high-pressure/high-temperature (HP/HT) treatment. Nanocarbon (C60, soot, graphite and nanodiamond) was used as an additive. New nanostructured and modified by nanocarbon bulk samples has been sintered from appropriate nanoclusters.

  14. Structure and properties of composites based chitosan and carbon nanostructures: atomistic and coarse-grained simulation

    NASA Astrophysics Data System (ADS)

    Glukhova, O. E.; Kolesnikova, A. S.; Grishina, O. A.; Slepchenkov, M. M.

    2015-03-01

    At the present time actual task of the modern materials is the creation of biodegradable biocompatible composite materials possessing high strength properties for medical purposes. One of the most promising biomaterials from a position of creation on their basis super strong nanofibres is chitosan. The aim of this work is a theoretical study of the structural features and physico-mechanical properties of biocomposite materials based on chitosan and carbon nanostructures. As matrix nanocomposite we considered various carbon nano-objects, namely carbon nanotubes and graphene. Using the developed original software complex KVAZAR we built atomistic and coarse-grained models of the biocomposite material. To identify regularities of influence of the configuration of the carbon matrix on the mechanical and electronic properties of biocomposite we carried out a series of numerical experiments using a classical algorithm of molecular dynamics and semi-empirical methods. The obtained results allow us to suggest that the generated biocomposite based on chitosan and carbon nanostructures has high stability and strength characteristics. Such materials can be used in biomedicine as a base material for creating of artificial limbs.

  15. Composite materials: A compilation

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Design, analysis and fabrication techniques for boron-aluminum composite-structure technology is presented and a new method of joining different laminated composites without mechanical fasteners is proposed. Also discussed is a low-cost procedure for rigidifying expanded honeycomb tubing and piping simulations. A brief note on patent information is added.

  16. Magnetic Cluster States in Nanostructured Materials

    SciTech Connect

    Diandra Leslie-Pelecky

    2008-06-13

    The goal of this work is to fabricate model nanomaterials with different types of disorder and use atomic-scale characterization and macroscopic magnetization measurements to understand better how specific types of disorder affects macroscopic magnetic behavior. This information can be used to produce magnetic nanomaterials with specific properties for applications such as permanent magnets, soft magnetic material for motors and biomedical applications.

  17. Composite structural materials. [aircraft structures

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1980-01-01

    The use of filamentary composite materials in the design and construction of primary aircraft structures is considered with emphasis on efforts to develop advanced technology in the areas of physical properties, structural concepts and analysis, manufacturing, and reliability and life prediction. The redesign of a main spar/rib region on the Boeing 727 elevator near its actuator attachment point is discussed. A composite fabrication and test facility is described as well as the use of minicomputers for computer aided design. Other topics covered include (1) advanced structural analysis methids for composites; (2) ultrasonic nondestructive testing of composite structures; (3) optimum combination of hardeners in the cure of epoxy; (4) fatigue in composite materials; (5) resin matrix characterization and properties; (6) postbuckling analysis of curved laminate composite panels; and (7) acoustic emission testing of composite tensile specimens.

  18. Mechanical Properties of Nanostructured Materials Determined Through Molecular Modeling Techniques

    NASA Technical Reports Server (NTRS)

    Clancy, Thomas C.; Gates, Thomas S.

    2005-01-01

    The potential for gains in material properties over conventional materials has motivated an effort to develop novel nanostructured materials for aerospace applications. These novel materials typically consist of a polymer matrix reinforced with particles on the nanometer length scale. In this study, molecular modeling is used to construct fully atomistic models of a carbon nanotube embedded in an epoxy polymer matrix. Functionalization of the nanotube which consists of the introduction of direct chemical bonding between the polymer matrix and the nanotube, hence providing a load transfer mechanism, is systematically varied. The relative effectiveness of functionalization in a nanostructured material may depend on a variety of factors related to the details of the chemical bonding and the polymer structure at the nanotube-polymer interface. The objective of this modeling is to determine what influence the details of functionalization of the carbon nanotube with the polymer matrix has on the resulting mechanical properties. By considering a range of degree of functionalization, the structure-property relationships of these materials is examined and mechanical properties of these models are calculated using standard techniques.

  19. Designing nanostructured magnetic materials by symmetry

    NASA Astrophysics Data System (ADS)

    Cowburn, R. P.; Koltsov, D. K.; Adeyeye, A. O.; Welland, M. E.

    1999-10-01

    We have investigated experimentally the influence of the geometric shape of deep sub-micron nanomagnets on their magnetic properties. We have used high-resolution electron beam lithography to make arrays of nanomagnets in the size range 40-500 nm which had rectangular, triangular, square and pentagonal geometries, corresponding, respectively, to rotational symmetries of order 2, 3, 4 and 5. The parent material was Supermalloy (Ni80Fe14Mo5). We find that an enormously wide range of magnetic properties, including some not found in conventional unstructured materials, can be obtained by using different geometries. We demonstrate that this is because the geometric shape imposes a strong anisotropy field of related symmetry order on the nanomagnet via a recently discovered phenomenon called configurational anisotropy. We show that the coercive field and remanence of these structures is determined directly by this anisotropy.

  20. Lamellar Self-Assembly Nanostructured Magnetic Materials

    Microsoft Academic Search

    B. Hamdoun

    2004-01-01

    Synthesis of lamellar self-assemblies symmetric polystyrene–polybutylmethacrylate (PS–PBMA) copolymers, doped by magnetic nanoparticles was described. Self-assembly is a spontaneous process by which molecules and nanophase entities may materialize into organized aggregates or networks. As soon as particles are coated by a grafted PS layer, they can be confined in the PS layer of the polymeric smectic. The lamellar order was maintained

  1. Designing nanostructured magnetic materials by symmetry

    Microsoft Academic Search

    R. P. Cowburn; D. K. Koltsov; A. O. Adeyeye; M. E. Welland

    1999-01-01

    We have investigated experimentally the influence of the geometric shape of deep sub-micron nanomagnets on their magnetic properties. We have used high-resolution electron beam lithography to make arrays of nanomagnets in the size range 40-500 nm which had rectangular, triangular, square and pentagonal geometries, corresponding, respectively, to rotational symmetries of order 2, 3, 4 and 5. The parent material was

  2. Improving the capacity of sodium ion battery using a virus-templated nanostructured composite cathode.

    PubMed

    Moradi, Maryam; Li, Zheng; Qi, Jifa; Xing, Wenting; Xiang, Kai; Chiang, Yet-Ming; Belcher, Angela M

    2015-05-13

    In this work we investigated an energy-efficient biotemplated route to synthesize nanostructured FePO4 for sodium-based batteries. Self-assembled M13 viruses and single wall carbon nanotubes (SWCNTs) have been used as a template to grow amorphous FePO4 nanoparticles at room temperature (the active composite is denoted as Bio-FePO4-CNT) to enhance the electronic conductivity of the active material. Preliminary tests demonstrate a discharge capacity as high as 166 mAh/g at C/10 rate, corresponding to composition Na0.9FePO4, which along with higher C-rate tests show this material to have the highest capacity and power performance reported for amorphous FePO4 electrodes to date. PMID:25811762

  3. Nanostructured Materials for Portable and Stationary Energy Storage

    NASA Astrophysics Data System (ADS)

    Cui, Yi

    2012-02-01

    Storing energy electrochemically involves electronic and ionic processes and chemical transformation inside and at the interface of materials. The ability to understand and design nanostructures and their interfaces afford the great opportunities for controlling these fundamental processes, which can ultimately lead to high performance energy storage devices. Here I will present several exciting examples on designing nanostructures and their interfaces to realize high performance energy storage devices. One example is on designing nanowires and heterostructured nanowires for ultrahigh capacity storage of lithium ions in silicon anodes and sulfur cathodes. The challenges associated with large volume expansion, electron and ion transport, and solid-electrolyte-interphase (SEI) have been addressed. Another example is to design open framework stucture of nanocrystals, which facility facile insertion of sodium and potassium ions. The high power, high energy efficiency and low-cost aqueous batteries can be enabled for grid scale stationary storage.

  4. Thermal properties of graphene and nanostructured carbon materials

    NASA Astrophysics Data System (ADS)

    Balandin, Alexander A.

    2011-08-01

    Recent years have seen a rapid growth of interest by the scientific and engineering communities in the thermal properties of materials. Heat removal has become a crucial issue for continuing progress in the electronic industry, and thermal conduction in low-dimensional structures has revealed truly intriguing features. Carbon allotropes and their derivatives occupy a unique place in terms of their ability to conduct heat. The room-temperature thermal conductivity of carbon materials span an extraordinary large range -- of over five orders of magnitude -- from the lowest in amorphous carbons to the highest in graphene and carbon nanotubes. Here, I review the thermal properties of carbon materials focusing on recent results for graphene, carbon nanotubes and nanostructured carbon materials with different degrees of disorder. Special attention is given to the unusual size dependence of heat conduction in two-dimensional crystals and, specifically, in graphene. I also describe the prospects of applications of graphene and carbon materials for thermal management of electronics.

  5. Nanostructured Materials Utilized in Biopolymer-based Plastics for Food Packaging Applications.

    PubMed

    Ghanbarzadeh, Babak; Oleyaei, Seyed Amir; Almasi, Hadi

    2015-10-15

    Most materials currently used for food packaging are nondegradable, generating environmental problems. Several biopolymers have been exploited to develop materials for ecofriendly food packaging. However, the use of biopolymers has been limited because of their usually poor mechanical and barrier properties, which may be improved by adding reinforcing compounds (fillers), forming composites. Most reinforced materials present poor matrix-filler interactions, which tend to improve with decreasing filler dimensions. The use of fillers with at least one nanoscale dimension (nanoparticles) produces nanocomposites. Nanoparticles have proportionally larger surface area than their microscale counterparts, which favors the filler-matrix interactions and the performance of the resulting material. Besides nanoreinforcements, nanoparticles can have other functions when added to a polymer, such as antimicrobial activity, etc. in this review paper, the structure and properties of main kinds of nanostructured materials which have been studied to use as nanofiller in biopolymer matrices are overviewed, as well as their effects and applications. PMID:24798951

  6. Composite structural materials. [aircraft applications

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1981-01-01

    The development of composite materials for aircraft applications is addressed with specific consideration of physical properties, structural concepts and analysis, manufacturing, reliability, and life prediction. The design and flight testing of composite ultralight gliders is documented. Advances in computer aided design and methods for nondestructive testing are also discussed.

  7. Fabrication of bioinspired nanostructured materials via colloidal self-assembly

    NASA Astrophysics Data System (ADS)

    Huang, Wei-Han

    Through millions of years of evolution, nature creates unique structures and materials that exhibit remarkable performance on mechanicals, opticals, and physical properties. For instance, nacre (mother of pearl), bone and tooth show excellent combination of strong minerals and elastic proteins as reinforced materials. Structured butterfly's wing and moth's eye can selectively reflect light or absorb light without dyes. Lotus leaf and cicada's wing are superhydrophobic to prevent water accumulation. The principles of particular biological capabilities, attributed to the highly sophisticated structures with complex hierarchical designs, have been extensively studied. Recently, a large variety of novel materials have been enabled by natural-inspired designs and nanotechnologies. These advanced materials will have huge impact on practical applications. We have utilized bottom-up approaches to fabricate nacre-like nanocomposites with "brick and mortar" structures. First, we used self-assembly processes, including convective self-assembly, dip-coating, and electrophoretic deposition to form well oriented layer structure of synthesized gibbsite (aluminum hydroxide) nanoplatelets. Low viscous monomer was permeated into layered nanoplatelets and followed by photo-curing. Gibbsite-polymer composite displays 2 times higher tensile strength and 3 times higher modulus when compared with pure polymer. More improvement occurred when surface-modified gibbsite platelets were cross-linked with the polymer matrix. We observed ˜4 times higher strength and nearly 1 order of magnitude higher modulus than pure polymer. To further improve the mechanical strength and toughness of inorganicorganic nanocomposites, we exploited ultrastrong graphene oxide (GO), a single atom thick hexagonal carbon sheet with pendant oxidation groups. GO nanocomposite is made by co-filtrating GO/polyvinyl alcohol suspension on 0.2 im pore-sized membrane. It shows ˜2 times higher strength and ˜15 times higher ultimate strains than nacre and pure GO paper (also synthesized by filtration). Specifically, it exhibits ˜30 times higher fracture energy than filtrated graphene paper and nacre, ˜100 times tougher than filtrated GO paper. Besides reinforced nanocomposites, we further explored the self-assembly of spherical colloids and the templating nanofabrication of moth-eye-inspired broadband antireflection coatings. Binary crystalline structures can be easily accomplished by spin-coating double-layer nonclose-packed colloidal crystals as templates, followed by colloidal templating. The polymer matrix between self-assembled colloidal crystal has been used as a sacrificial template to define the resulting periodic binary nanostructures, including intercalated arrays of silica spheres and polymer posts, gold nanohole arrays with binary sizes, and dimple-nipple antireflection coatings. The binary-structured antireflection coatings exhibit better antireflective properties than unitary coatings. Natural optical structures and nanocomposites teach us a great deal on how to create high performance artificial materials. The bottom-up technologies developed in this thesis are scalable and compatible with standard industrial processes, promising for manufacturing high-performance materials for the benefits of human beings.

  8. Hierarchical oxide-based composite nanostructures for energy, environmental, and sensing applications

    Microsoft Academic Search

    Pu-Xian Gao; Paresh Shimpi; Wenjie Cai; Haiyong Gao; Dunliang Jian; Gregory Wrobel

    2011-01-01

    Self-assembled composite nanostructures integrate various basic nano-elements such as nanoparticles, nanofilms and nanowires toward realizing multifunctional characteristics, which promises an important route with potentially high reward for the fast evolving nanoscience and nanotechnology. A broad array of hierarchical metal oxide based nanostructures have been designed and fabricated in our research group, involving semiconductor metal oxides, ternary functional oxides such as

  9. Novel Nanostructured Materials for Hydrogen Storage

    NASA Astrophysics Data System (ADS)

    Dillon, Anne

    2005-03-01

    The United States Department of Energy's (DOE's) Office of Energy Efficiency and Renewable Energy and the Office of Basic Sciences have concluded that hydrogen storage is a cornerstone technology for implementing a hydrogen energy economy. However, significant scientific advancement is still required if a viable on-board storage technology is to be developed. For example, an adsorption process for on-board vehicular storage will require a hydrogen binding energy between ˜20-60 kJ/mol to allow for near-room temperature operation at reasonable pressures. Typically, non-dissociative physisorption due purely to van der Waals forces involves a binding energy of only ˜ 4 kJ/mol, whereas a chemical bond is ˜ 400 kJ/mol. The desired binding energy range for vehicular hydrogen storage therefore dictates that molecular H2 be stabilized in an unusual manor. Hydrogen adsorption has been observed with a binding energy of ˜ 50 kJ /mol on carbon multi-wall nanotubes (MWNTs) containing iron nanoparticles at their tips. However, hydrogen adsorption at near ambient conditions is neither anticipated nor observed on either purified MWNTs or iron nanoparticles by themselves. Recent theoretical studies have shown that an iron adatom forms a complex with a C36 fullerene and shares charge with four carbon atoms of a bent five-membered ring in the C36 molecule. Three H2 ligands then also coordinate with the iron forming a stable 18-electron organo-metallic complex. Here the binding energy of the molecular hydrogen ligands is ˜ 43 kJ /mol. It is believed that a similar interaction may be occurring for MWNTs containing iron nanoparticles. However, a more optimized material must be produced in order to increase the hydrogen capacity. Iron has also been predicted to complex with all twelve of the five-membered rings in C60 with a binding energy of ˜42 kJ/mol and an H2 capacity of 4.9 wt.%. Further, Scandium has been shown to complex with the twelve five-membered rings in C60 with a binding energy of ˜42 kJ/mol and an H2 capacity of 8.7 wt.%. These theoretical findings as well as experimental efforts to synthesize organo-metallic fullerene complexes for vehicular hydrogen storage applications will be discussed in detail.

  10. Recycling of composite materials

    Microsoft Academic Search

    M. Buggy; L. Farragher; W. Madden

    1995-01-01

    An economic survey of composite manufacturing was carried out to help to identify suitable fibre\\/resin systems for recycling trials. Three separate recycling strategies were also adopted. The first of these was the re-use of in-process polyester\\/glass prepreg offcuts, which were quantified and then reprocessed using a simple pressing technique. Three different panel types were pressed and subjected to comparative physical

  11. Nanostructure multilayer materials for capacitor energy storage for EH vehicles

    SciTech Connect

    Barbee, T.W. Jr.; Johnson, C.W.

    1995-02-01

    Acceleration and regenerative breaking for electric and hybrid vehicles require high power capacitors to complement energy sources. Large, flat nanostructure multilayer capacitors (NMCS) can provide load balancing capacitance in EHVs of the future. Additional uses include snubber capacitors for power electronics such as motor drives, energy discharge capacitors for lasers, and numerous industrial and military electronics applications [1]. In the present work, we demonstrate the effectiveness of LLNL`s multilayer materials technology by fabricating NMC test films with high energy and power density.

  12. Ski Technology And Composite Materials

    NSDL National Science Digital Library

    2010-01-01

    The following resource is from Lessonopoly, which has created student activities and lesson plans to support the video series, Science of the Olympic Winter Games, created by NBC Learn and the National Science Foundation. Featuring exclusive footage from NBC Sports and contributions from Olympic athletes and NSF scientists, the series will help teach your students valuable scientific concepts. Students will learn the basic engineering issues related to ski design. They will learn about composite materials and polymer materials. Also, students will create and test a composite material.

  13. Nanophase and Composite Optical Materials

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This talk will focus on accomplishments, current developments, and future directions of our work on composite optical materials for microgravity science and space exploration. This research spans the order parameter from quasi-fractal structures such as sol-gels and other aggregated or porous media, to statistically random cluster media such as metal colloids, to highly ordered materials such as layered media and photonic bandgap materials. The common focus is on flexible materials that can be used to produce composite or artificial materials with superior optical properties that could not be achieved with homogeneous materials. Applications of this work to NASA exploration goals such as terraforming, biosensors, solar sails, solar cells, and vehicle health monitoring, will be discussed.

  14. Multi-walled carbon nanotube\\/nanostructured zirconia composites: Outstanding mechanical properties in a wide range of temperature

    Microsoft Academic Search

    Mehdi Mazaheri; Daniele Mari; Zohreh Razavi Hesabi; Robert Schaller; Gilbert Fantozzi

    2011-01-01

    Multi-walled carbon nanotube (MWCNT)\\/nanostructured zirconia composites with a homogenous distribution of different MWCNT quantities (ranging within 0.5–5wt.%) were developed. By using Spark Plasma Sintering we succeeded in preserving the MWCNTs firmly attached to zirconia grains and in obtaining fully dense materials. Moreover, MWCNTs reduce grain growth and keep a nanosize structure. A significant improvement in room temperature fracture toughness and

  15. High-temperature composite materials

    Microsoft Academic Search

    Yu. L. Pilipovskii; L. G. Vishnevskii; T. V. Grudina; L. N. Pereselentseva

    1996-01-01

    In the second half of the 60's the development of composite materials extremely necessary in service under conditions of intense short-term action of high-temperature gas flows which bear a significant quantity of condensed phase was started in the Institute of Material Science under the leadership of I. N. Frantsevich and then D. M. Karpinos. These materials must possess high erosion-

  16. Composite materials for space applications

    NASA Technical Reports Server (NTRS)

    Rawal, Suraj P.; Misra, Mohan S.; Wendt, Robert G.

    1990-01-01

    The objectives of the program were to: generate mechanical, thermal, and physical property test data for as-fabricated advanced materials; design and fabricate an accelerated thermal cycling chamber; and determine the effect of thermal cycling on thermomechanical properties and dimensional stability of composites. In the current program, extensive mechanical and thermophysical property tests of various organic matrix, metal matrix, glass matrix, and carbon-carbon composites were conducted, and a reliable database was constructed for spacecraft material selection. Material property results for the majority of the as-fabricated composites were consistent with the predicted values, providing a measure of consolidation integrity attained during fabrication. To determine the effect of thermal cycling on mechanical properties, microcracking, and thermal expansion behavior, approximately 500 composite specimens were exposed to 10,000 cycles between -150 and +150 F. These specimens were placed in a large (18 cu ft work space) thermal cycling chamber that was specially designed and fabricated to simulate one year low earth orbital (LEO) thermal cycling in 20 days. With this rate of thermal cycling, this is the largest thermal cycling unit in the country. Material property measurements of the thermal cycled organic matrix composite laminate specimens exhibited less than 24 percent decrease in strength, whereas, the remaining materials exhibited less than 8 percent decrease in strength. The thermal expansion response of each of the thermal cycled specimens revealed significant reduction in hysteresis and residual strain, and the average CTE values were close to the predicted values.

  17. Structural and magnetic characterization of nanostructured iron composites formed in the presence of citrate

    Microsoft Academic Search

    Thomas F. Ekiert Jr.

    2009-01-01

    A variety of nanostructured iron composites have been prepared via the self-assembly of nanocrystalline iron particles formed in the presence of citrate ions. Through an appropriate choice of the ratio of citrate to iron ions, the self-assembled, nanostructured iron composites can be prepared so as to possess diminished coercivity, nearly the bulk magnetization of iron, and air-stability for many months,

  18. Nanomanufacturing : nano-structured materials made layer-by-layer.

    SciTech Connect

    Cox, James V.; Cheng, Shengfeng; Grest, Gary Stephen; Tjiptowidjojo, Kristianto (University of New Mexico); Reedy, Earl David, Jr.; Fan, Hongyou; Schunk, Peter Randall; Chandross, Michael Evan; Roberts, Scott A.

    2011-10-01

    Large-scale, high-throughput production of nano-structured materials (i.e. nanomanufacturing) is a strategic area in manufacturing, with markets projected to exceed $1T by 2015. Nanomanufacturing is still in its infancy; process/product developments are costly and only touch on potential opportunities enabled by growing nanoscience discoveries. The greatest promise for high-volume manufacturing lies in age-old coating and imprinting operations. For materials with tailored nm-scale structure, imprinting/embossing must be achieved at high speeds (roll-to-roll) and/or over large areas (batch operation) with feature sizes less than 100 nm. Dispersion coatings with nanoparticles can also tailor structure through self- or directed-assembly. Layering films structured with these processes have tremendous potential for efficient manufacturing of microelectronics, photovoltaics and other topical nano-structured devices. This project is designed to perform the requisite R and D to bring Sandia's technology base in computational mechanics to bear on this scale-up problem. Project focus is enforced by addressing a promising imprinting process currently being commercialized.

  19. Fiber composite materials technology development

    SciTech Connect

    Chiao, T.T.

    1980-10-23

    The FY1980 technical accomplishments from the Lawrence Livermore National laboratory (LLNL) for the Fiber Composite Materials Technology Development Task fo the MEST project are summarized. The task is divided into three areas: Engineering data base for flywheel design (Washington University will report this part separately), new materials evaluation, and time-dependent behavior of Kevlar composite strands. An epoxy matrix was formulated which can be used in composites for 120/sup 0/C service with good processing and mechanical properties. Preliminary results on the time-dependent properties of the Kevlar 49/epoxy strands indicate: Fatigue loading, as compared to sustained loading, drastically reduces the lifetime of a Kevlar composie; the more the number of on-off load cycles, the less the lifetime; and dynamic fatigue of the Kevlar composite can not be predicted by current damage theories such as Miner's Rule.

  20. Graphene-based semiconductor and metallic nanostructured materials

    NASA Astrophysics Data System (ADS)

    Zedan, Abdallah F.

    Exciting periods of scientific research are often associated with discoveries of novel materials. Such period was brought about by the successful preparation of graphene which is a 2D allotrope of carbon with remarkable electronic, optical and mechanical properties. Functional graphene-based nanocomposites have great promise for applications in various fields such as energy conversion, opteoelectronics, solar cells, sensing, catalysis and biomedicine. Herein, microwave and laser-assisted synthetic approaches were developed for decorating graphene with various semiconductor, metallic or magnetic nanostructures of controlled size and shape. We developed a scalable microwave irradiation method for the synthesis of graphene decorated with CdSe nanocrystals of controlled size, shape and crystalline structure. The efficient quenching of photoluminescence from the CdSe nanocrystals by graphene has been explored. The results provide a new approach for exploring the size-tunable optical properties of CdSe nanocrystals supported on graphene which could have important implications for energy conversion applications. We also extended this approach to the synthesis of Au-ceria-graphene nanocomposites. The synthesis is facilely conducted at mild conditions using ethylenediamine as a solvent. Results reveal significant CO conversion percentages between 60-70% at ambient temperatures. Au nanostructures have received significant attention because of the feasibility to tune their optical properties by changing size or shape. The coupling of the photothermal effects of these Au nanostructures of controlled size and shape with GO nanosheets dispersed in water is demonstrated. Our results indicate that the enhanced photothermal energy conversion of the Au-GO suspensions could to lead to a remarkable increase in the heating efficiency of the laser-induced melting and size reduction of Au nanostructures. The Au-graphene nanocomposites are potential materials for photothermolysis, thermochemical and thermomechanical applications. We developed a facile method for decorating graphene with magnetite nanocrystals of various shapes (namely, spheres, cubes and prisms) by the microwave-assisted-reduction of iron acetylacetonate in benzyl ether. The shape control was achieved by tuning the mole ratio between the oleic acid and the oleyamine. The structural, morphological and physical properties of graphene-based nanocomposites described herein were studied using standard characterization tools such as TEM, SEM, UV-Vis and PL spectroscopy, powder X-ray diffraction, XPS and Raman spectroscopy.

  1. Thermal Characterization of Nanostructures and Advanced Engineered Materials

    NASA Astrophysics Data System (ADS)

    Goyal, Vivek Kumar

    Continuous downscaling of Si complementary metal-oxide semiconductor (CMOS) technology and progress in high-power electronics demand more efficient heat removal techniques to handle the increasing power density and rising temperature of hot spots. For this reason, it is important to investigate thermal properties of materials at nanometer scale and identify materials with the extremely large or extremely low thermal conductivity for applications as heat spreaders or heat insulators in the next generation of integrated circuits. The thin films used in microelectronic and photonic devices need to have high thermal conductivity in order to transfer the dissipated power to heat sinks more effectively. On the other hand, thermoelectric devices call for materials or structures with low thermal conductivity because the performance of thermoelectric devices is determined by the figure of merit Z=S2sigma/K, where S is the Seebeck coefficient, K and sigma are the thermal and electrical conductivity, respectively. Nanostructured superlattices can have drastically reduced thermal conductivity as compared to their bulk counterparts making them promising candidates for high-efficiency thermoelectric materials. Other applications calling for thin films with low thermal conductivity value are high-temperature coatings for engines. Thus, materials with both high thermal conductivity and low thermal conductivity are technologically important. The increasing temperature of the hot spots in state-of-the-art chips stimulates the search for innovative methods for heat removal. One promising approach is to incorporate materials, which have high thermal conductivity into the chip design. Two suitable candidates for such applications are diamond and graphene. Another approach is to integrate the high-efficiency thermoelectric elements for on-spot cooling. In addition, there is strong motivation for improved thermal interface materials (TIMs) for heat transfer from the heat-generating chip to heat-sinking units. This dissertation presents results of the experimental investigation and theoretical interpretation of thermal transport in the advanced engineered materials, which include thin films for thermal management of nanoscale devices, nanostructured superlattices as promising candidates for high-efficiency thermoelectric materials, and improved TIMs with graphene and metal particles as fillers providing enhanced thermal conductivity. The advanced engineered materials studied include chemical vapor deposition (CVD) grown ultrananocrystalline diamond (UNCD) and microcrystalline diamond (MCD) films on Si substrates, directly integrated nanocrystalline diamond (NCD) films on GaN, free-standing polycrystalline graphene (PCG) films, graphene oxide (GOx) films, and "pseudo-superlattices" of the mechanically exfoliated Bi2Te3 topological insulator films, and thermal interface materials (TIMs) with graphene fillers.

  2. Strong and ductile nanostructured Cu-carbon nanotube composite Hongqi Li,1,a

    E-print Network

    Zhu, Yuntian T.

    properties make CNTs an ideal nanoscale reinforcement to tailor multifunctional composites with optimalStrong and ductile nanostructured Cu-carbon nanotube composite Hongqi Li,1,a Amit Misra,1 Zenji composite grain size 25 nm with high strength and good ductility was developed. Pillar testing reveals

  3. Fracture problems in composite materials

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1972-01-01

    A series of fracture problems in composite materials are identified, their methods of solution are briefly discussed, and some sample results are presented. The main problem of interest is the determination of the stress state in the neighborhood of localized imperfections such as cracks and inclusions which may exist in the composite. Particular emphasis is placed on the evaluation of quantities such as the stress intensity factors, the power of the stress singularity, and the strain energy release rate, which may be used directly or indirectly in connection with an appropriate fracture criterion for the prediction of fracture initiation and propagation load levels. The topics discussed include a crack in layered composites, a crack terminating at and going through a bi-material interface, a penny-shaped crack in a filament-reinforced elastic matrix, and inclusion problems in bonded materials.

  4. Composite material impregnation unit

    NASA Technical Reports Server (NTRS)

    Wilkinson, S. P.; Marchello, J. M.; Johnston, N. J.

    1993-01-01

    This memorandum presents an introduction to the NASA multi-purpose prepregging unit which is now installed and fully operational at the Langley Research Center in the Polymeric Materials Branch. A description of the various impregnation methods that are available to the prepregger are presented. Machine operating details and protocol are provided for its various modes of operation. These include, where appropriate, the related equations for predicting the desired prepreg specifications. Also, as the prepregger is modular in its construction, each individual section is described and discussed. Safety concerns are an important factor and a chapter has been included that highlights the major safety features. Initial experiences and observations for fiber impregnation are described. These first observations have given great insight into the areas of future work that need to be addressed. Future memorandums will focus on these individual processes and their related problems.

  5. High performance capacitors using nano-structure multilayer materials fabrication

    DOEpatents

    Barbee, Jr., Troy W. (Palo Alto, CA); Johnson, Gary W. (Livermore, CA); O'Brien, Dennis W. (Livermore, CA)

    1995-01-01

    A high performance capacitor fabricated from nano-structure multilayer materials, such as by controlled, reactive sputtering, and having very high energy-density, high specific energy and high voltage breakdown. The multilayer capacitors, for example, may be fabricated in a "notepad" configuration composed of 200-300 alternating layers of conductive and dielectric materials so as to have a thickness of 1 mm, width of 200 mm, and length of 300 mm, with terminals at each end of the layers suitable for brazing, thereby guaranteeing low contact resistance and high durability. The "notepad" capacitors may be stacked in single or multiple rows (series-parallel banks) to increase the voltage and energy density.

  6. High performance capacitors using nano-structure multilayer materials fabrication

    DOEpatents

    Barbee, T.W. Jr.; Johnson, G.W.; O`Brien, D.W.

    1996-01-23

    A high performance capacitor is described which is fabricated from nano-structure multilayer materials, such as by controlled, reactive sputtering, and having very high energy-density, high specific energy and high voltage breakdown. The multilayer capacitors, for example, may be fabricated in a ``notepad`` configuration composed of 200--300 alternating layers of conductive and dielectric materials so as to have a thickness of 1 mm, width of 200 mm, and length of 300 mm, with terminals at each end of the layers suitable for brazing, thereby guaranteeing low contact resistance and high durability. The ``notepad`` capacitors may be stacked in single or multiple rows (series-parallel banks) to increase the voltage and energy density. 5 figs.

  7. High performance capacitors using nano-structure multilayer materials fabrication

    DOEpatents

    Barbee, Jr., Troy W. (Palo Alto, CA); Johnson, Gary W. (Livermore, CA); O'Brien, Dennis W. (Livermore, CA)

    1996-01-01

    A high performance capacitor fabricated from nano-structure multilayer materials, such as by controlled, reactive sputtering, and having very high energy-density, high specific energy and high voltage breakdown. The multilayer capacitors, for example, may be fabricated in a "notepad" configuration composed of 200-300 alternating layers of conductive and dielectric materials so as to have a thickness of 1 mm, width of 200 mm, and length of 300 mm, with terminals at each end of the layers suitable for brazing, thereby guaranteeing low contact resistance and high durability. The "notepad" capacitors may be stacked in single or multiple rows (series-parallel banks) to increase the voltage and energy density.

  8. Fundamental study and practical applications of composite colloidal nanostructures

    NASA Astrophysics Data System (ADS)

    Goebl, James Andrew

    In recent years, nanomaterials, defined as materials with a size of < 100 nm in at least one axis, have attracted widespread interest due to their promise in many applications. Due to their small sizes, nanoparticles exhibit unique properties not found in their bulk counterparts, such as superparamagnetism in magnetic nanoparticles, as well as quantized plasma oscillations leading to well-defined extinction peaks in metal nanoparticles. Although many fabrication techniques exist to produce these unique materials, colloidal nanomaterials are of particular importance due to their low cost and ready scalability, and their easy suspension in solutions. Current research focuses on improving syntheses and developing new types of materials with novel properties, as well as studying the underlying mechanisms behind their growth in solution. One area of investigation involves producing composite nanomaterials, which contain two or more different nanoscale components. By making a composite material, it is possible to produce a material which possesses the properties of all of its components, or even a material with entirely new properties. Composite materials can also be produced as intermediates, often with one material acting as a sacrificial template which is later removed, to produce a material with a morphology unattainable with conventional synthesis. In this work, a variety of uses have been explored for colloidal nanoscale composites. First, the mechanism for the seeded growth of 2D silver nanoplates was studied through a marker experiment. Prior to growth, a thin layer of gold was deposited on the plate edges, which defined the original boundary of the nanoplate seed, allowing easy observation of the direction of growth and making it possible to explain previously observed shape transitions during this process. In later work, gold microplates were conjugated to amine-terminated magnetic nanoparticles to create a material which was both anisotropic, magnetic, and highly reflective. This composite was studied as a micron-size actuated mirror system, which was found to have a fast magnetic response and good optical contrast between the "on" and "off" states. Finally, a gold-titania core-shell composite was developed, which proved resistant to high-temperature sintering and was able to photocatalytically produce hydrogen from ethanol.

  9. Materials for Hydrogen Storage: From Complex Hydrides to Functionalized Nanostructures

    NASA Astrophysics Data System (ADS)

    Das, G. P.

    2011-07-01

    The world wide effort for a transition to renewable and clean (i.e. carbon-free) form of energy has resulted in an upsurge of interest in harnessing and utilizing Hydrogen. Apart from being the most abundant element in the universe, hydrogen offers many advantages over other fuels: it is non-toxic, clean to use, and packs more energy per mass than any other fuel. Hydrogen energy production, storage and distribution constitute a multi-disciplinary area of research. Coming to the material issues for solid state storage of hydrogen, the most desirable criteria are high storage capacity, satisfactory kinetics, and optimal thermodynamics. Complex hydrides involving light metals, such as Alanates, Imides, Borates, Amidoboranes etc. show impressive gravimetric efficiencies, although the hydrogen desorption temperatures turn out to be rather high. Apart from complex hydrides, there are other kinds of novel materials that have been investigated, e.g. carbon based materials activated with nano-catalysts, clathrate hydrates, metal-organic complexes, and more recently nanostructured cages viz. fullerenes and nanotubes decorated with simple or transition metals that serve to attract hydrogen in molecular form. In this talk, after giving a broad overview on hydrogen economy, I shall focus on first-principles design of materials for hydrogen storage, from complex hydrides to various kinds of functinalized nanostructures, and discuss the recent results obtained in our laboratory [1-6]. Some outstanding issues and challenges, like how to circumvent the problem of metal clustering on surface, or how to bring down the hydrogen desorption temperature etc. will be discussed.

  10. Impact response of composite materials

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Srinivasan, K.

    1991-01-01

    Composite materials composed of carbon fibers and resin matrices offer great promise in reducing the weight of aerospace structures. However they remain extremely vulnerable to out of plane impact loads, which lead to severe losses in strength and stiffness. The results of an experimental program, undertaken to investigate the low velocity impact damage tolerance of composite materials is presented. The objectives were to identify key neat resin/composite properties that lead to enhancement of composite impact damage tolerance and to find a small scale test that predicts compression after impact properties of panels. Five materials were selected for evaluation. These systems represented different classes of material behavior such as brittle epoxy, modified epoxies, and amorphous and semicrystalling thermoplastics. The influence of fiber properties on the impact performance was also studied in one material, i.e., in polyether ether ketone (PEEK). Several 24 and 48 ply quasi-isotropic and 24 ply orthotropic laminates were examined using an instrumented drop weight impactor. Correlations with post impact compression behavior were made.

  11. Cluster-assembled materials: a new class of nanostructured materials with original structures and properties

    NASA Astrophysics Data System (ADS)

    Perez, A.; Melinon, P.; Dupuis, V.; Tuaillon, J.; Prevel, Brigitte; Pellarin, M.; Vialle, J. L.; Broyer, Michel

    1996-04-01

    The low energy cluster beam deposition technique (LECBD) is used to produce nanostructured materials with original structures and properties. In this technique, clusters do not fragment upon impact on the substrate leading to the formation of granular films by nearly random stacking of incident clusters. Both nanostructured films and films of clusters embedded in various matrices are produced using this technique. The production and deposition of controlled size distributions of free clusters are briefly described as well as the specific nucleation and growth process characteristic of the LECBD. In the second part of the paper are presented some characteristic examples of novel materials prepared by this technique. The formation and properties of films of covalent materials (C, Si) and metallic materials (Fe, Co, Ni) are presented to emphasize the memory effect of the free cluster structure in the first case and the effect of the nanocrystalline film structure through the magnetic properties in the second case.

  12. Nanostructured nickel-free austenitic stainless steel/hydroxyapatite composites.

    PubMed

    Tulinski, Maciej; Jurczyk, Mieczyslaw

    2012-11-01

    In this work Ni-free austenitic stainless steels with nanostructure and their nanocomposites with hydroxyapatite are presented and characterized by means of X-ray diffraction and optical profiling. The samples were synthesized by mechanical alloying, heat treatment and nitriding of elemental microcrystalline powders with addition of hydroxyapatite (HA). In our work we wanted to introduce into stainless steel hydroxyapatite ceramics that have been intensively studied for bone repair and replacement applications. Such applications were chosen because of their high biocompatibility and ability to bond to bone. Since nickel-free austenitic stainless steels seem to have better mechanical properties, corrosion resistance and biocompatibility compared to 316L stainless steels, it is possible that composite made of this steel and HA could improve properties, as well. Mechanical alloying and nitriding are very effective technologies to improve the corrosion resistance of stainless steel. Similar process in case of nanocomposites of stainless steel with hydroxyapatite helps achieve even better mechanical properties and corrosion resistance. Hence nanocrystalline nickel-free stainless steels and nickel-free stainless steel/hydroxyapatite nanocomposites could be promising bionanomaterials for use as a hard tissue replacement implants, e.g., orthopedic implants. In such application, the surface roughness and more specifically the surface topography influences the proliferation of cells (e.g., osteoblasts). PMID:23421285

  13. Joining of polymer composite materials

    SciTech Connect

    Magness, F.H.

    1990-11-01

    Under ideal conditions load bearing structures would be designed without joints, thus eliminating a source of added weight, complexity and weakness. In reality the need for accessibility, repair, and inspectability, added to the size limitations imposed by the manufacturing process and transportation/assembly requirements mean that some minimum number of joints will be required in most structures. The designer generally has two methods for joining fiber composite materials, adhesive bonding and mechanical fastening. As the use of thermoplastic materials increases, a third joining technique -- welding -- will become more common. It is the purpose of this document to provide a review of the available sources pertinent to the design of joints in fiber composites. The primary emphasis is given to adhesive bonding and mechanical fastening with information coming from documentary sources as old as 1961 and as recent as 1989. A third, shorter section on composite welding is included in order to provide a relatively comprehensive treatment of the subject.

  14. Hugoniot Analysis of Composite Materials

    Microsoft Academic Search

    S. K. Garg; J. W. Kirsch

    1971-01-01

    A generalized set of conservation equations (i.e., the Hugoniot relations) across a disturbance propagating through a composite material with a steady velocity are derived within the framework of the Theory of Inter acting Continua. By providing a rational basis for comparison, the analysis clarifies the differences between the earlier studies in this field. In addition, the present development of the

  15. ADVANCED COMPOSITE MATERIALS HEAT BRIDGES

    Microsoft Academic Search

    A. B. Shopen; V. A. Golovanevskiy; O. A. Kivirenko

    Understanding heat transfer properties of advanced composite materials (CM) structures is gaining increasing importance in industries such as medicine and cryogenics, aerospace and electronics where structures made from advanced CM are being used as heat bridges. The main goal in such applications of advanced CM structures is achieving maximum load bearing capacity while maintaining heat transfer rate at a predetermined

  16. Durability of polymer composite materials

    Microsoft Academic Search

    Liu Liu

    2006-01-01

    The purpose of this research is to examine structural durability of advanced composite materials under critical loading conditions, e.g., combined thermal and mechanical loading and shear fatigue loading. A thermal buckling model of a burnt column, either axially restrained or under an axial applied force was developed. It was predicted that for a column exposed to the high heat flux

  17. Enzyme Stabilization in Nanostructured Materials, for Use in Organophosphorus Nerve Agent Detoxification and Prophylaxis

    Microsoft Academic Search

    R. J. Kernchen

    \\u000a Enzyme immobilization and encapsulation in various nanostructures has drawn great interest as it offers both increased stability\\u000a and reusability without significant loss in activity. Although we are still at the beginning of exploring the use of these\\u000a materials for biocatalysis, by now several nanostructures have been tested as hosts for enzyme immobilization. The beneficial\\u000a application of enzyme stabilization in nanostructured

  18. Composite WO3/TiO2 nanostructures for high electrochromic activity.

    SciTech Connect

    Reyes, Karla Rosa; Stephens, Zachary Dan.; Robinson, David B.

    2013-05-01

    A composite material consisting of TiO2 nanotubes (NTs) with WO3 electrodeposited homogeneously on its surface has been fabricated, detached from its substrate, and attached to a fluorine-doped tin oxide film on glass for application to electrochromic (EC) reactions. A paste of TiO2 made from commercially available TiO2 nanoparticles creates an interface for the TiO2 NT film to attach to the FTO glass, which is conductive and does not cause solution-phase ions in an electrolyte to bind irreversibly with the material. The effect of NT length on the current density and the EC contrast of the material were studied. The EC redox reaction seen in this material is diffusion- limited, having relatively fast reaction rates at the electrode surface. The composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast and longer memory time compared with the pure WO3 and TiO2.

  19. New wear resistant composite material

    SciTech Connect

    Angers, R.; Champagne, B.; Fiset, M.; Chollet, P.

    1983-01-01

    A composite material consisting of WC-Co particles in a steel matrix was fabricated by sintering mixtures of WC-Co particles and a steel powder and infiltrating the sintered pieces with a copper alloy. Its wear resistance and mechanical properties were studied as a function of the content in WC-Co particles and other characteristics of the composite material microstructure. Infiltration provided a simple means to obtain a strong cohesion between WC-Co particles and the steel matrix. An effective matrix protection against wear is obtained with relatively low additions of particles especially with a silica abrasive which is soft with respect to cemented carbide. The experimental results show that this material has good mechanical properties and wear resistance. Depending upon abrasion resistance, wear losses are reduced up to 10 times by a 30 vol% addition of cemented carbide particles.

  20. [Biocomposite nanostructured materials for the bone defects filling by osteomyelitis].

    PubMed

    Chekmazov, I A; Riabov, A L; Skalozub, O I; Lapin, R V

    2013-01-01

    Results of the use of the biocomposite nanostructured material "KollapAn" in the treatment of 374 patients with osteomyelitis were followed up. 412 operations were performed, depending on the stage of the inflammatory process and clinical picture. Majorly, operation was performed on the 5-7th day after primary necrosequestrectomy. Good early anatomic results were achieved in 86% patients. All patients demonstrated the good functional results of the treatment; the wound healing was on-time. The lethality rate was 1.2%; all these patients had severe sepsis. The long-term follow up (1.5 years) revealed the complete substitution of the bone defect by the autobone; no cases of the osteomyelitis recurrence were observed. PMID:23996041

  1. Characterization of nanostructured material images using fractal descriptors

    E-print Network

    Florindo, João B; Pereira, Ernesto C; Bruno, Odemir M

    2012-01-01

    This work presents a methodology to the morphology analysis and characterization of nanostructured material images acquired from FEG-SEM (Field Emission Gun-Scanning Electron Microscopy) technique. The metrics were extracted from the image texture (mathematical surface) by the volumetric fractal descriptors, a methodology based on the Bouligand-Minkowski fractal dimension, which considers the properties of the Minkowski dilation of the surface points. An experiment with galvanostatic anodic titanium oxide samples prepared in oxalyc acid solution using different conditions of applied current, oxalyc acid concentration and solution temperature was performed. The results demonstrate that the approach is capable of characterizing complex morphology characteristics such as those present in the anodic titanium oxide.

  2. Computational modeling of composite material fires

    Microsoft Academic Search

    Alexander L. Brown; Kenneth L. Erickson; Joshua Allen Hubbard; Amanda B. Dodd

    2010-01-01

    Composite materials behave differently from conventional fuel sources and have the potential to smolder and burn for extended time periods. As the amount of composite materials on modern aircraft continues to increase, understanding the response of composites in fire environments becomes increasingly important. An effort is ongoing to enhance the capability to simulate composite material response in fires including the

  3. A study of nanostructure and properties of mixed nanotube buckypaper materials: Fabrication, process modeling characterization, and property modeling

    NASA Astrophysics Data System (ADS)

    Yeh, Cherng-Shii

    2007-12-01

    Single-walled carbon nanotube buckypaper (SBP) is a thin film of preformed nanotube networks that possesses many excellent properties. SBP is considered to be very promising in the development of high-performance composite materials; however, the high cost of single-walled nanotubes (SWNTs) limits industrial applications of SBP materials. Mixed buckypaper (MBP) is a more affordable alternative that combines SWNTs with low-cost multi-walled nanotubes (MWNTs) or carbon nanofibers (CNFs) to retain most of the excellent properties of SBP while significantly reducing the cost. This study proposes a manufacturing process of MBPs. The process parameters were studied through experimental design and statistical analysis. The parameters included mixing material type, mixing ratio, sonication effect, surfactant amount, and cleaning effect. The effects of the parameters on nanostructure uniformity, purity, Brunauer-Emmett-Teller (BET) surface area and electrical conductivity of the resultant MBPs were revealed. Results of the study show that all those parameters and their interactions are influential to the dispersion and uniformity of nanostructure and purity, but only mixing material type and ratio are influential to the BET surface area and electrical conductivity. To systematically reveal the process-nanostructure-property relationship of SBP and MBP materials, the nanostructures of the buckypapers were characterized as rope size, length and pore size distributions of the nanomaterials in resultant buckypapers. These distributions featured bimodal phenomenon due to different material mixtures; therefore, the distributions were further separated into two individual ones and fitted into Weibull distributions. Two nanostructure-property models of buckypaper materials were developed. The specific surface area model was built upon the characterization and analysis of buckypaper nanostructures. The model showed that rope size distribution and mixed ratio of nanomaterials are governing factors for the resultant specific surface area of buckypaper. The electrical conductivity model captured multiscale electrical transport phenomenon of nanotube networks in buckypapers. The model considered chirality, contact area, contact type, diameter, length and orientation distributions of nanotubes in buckypapers. The proposed models not only can predict property trends correctly, but can also reveal the critical process-nanostructure-property relationships of buckypaper materials. The results are important for the further tailoring and optimization of the manufacturing process and properties of nanotube buckypapers. Key Words: Carbon nanotubes, buckypaper, statistical analysis, uniformity, surface area, electrical conductivity

  4. Fracture problems in composite materials.

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1972-01-01

    In this paper a series of fracture problems in composite materials are identified, their methods of solution are briefly discussed, and some sample results are presented. The main problem of interest is the determination of the stress state in the neighborhood of localized imperfections such as cracks and inclusions which may exist in the composite. Particular emphasis is placed on the evaluation of quantities such as the stress intensity factors, the power of the stress singularity, and the strain energy release rate, which may be used directly or indirectly in connection with an appropriate fracture criterion for the prediction of fracture initiation and propagation load levels.

  5. Novel nano-structured materials: Preparation by self- assembly techniques and study of physical properties by x-ray analysis and magnetic characterization

    Microsoft Academic Search

    Joan Ann K. Wiemann

    2000-01-01

    The properties and characteristics of nano-structured materials can be quite different from the bulk form of the material. By forming nano-particles, electrical and magnetic properties may be tailored or enhanced beyond that of bulk materials. In this work several single and composite nano-phase materials were prepared by chemical or physical methods. Techniques used for characterization include magnetometry, Mössbauer analysis, x-ray

  6. Nanostructured composites obtained by ATRP sleeving of bacterial cellulose nanofibers with acrylate polymers.

    PubMed

    Lacerda, Paula S S; Barros-Timmons, Ana M M V; Freire, Carmen S R; Silvestre, Armando J D; Neto, Carlos P

    2013-06-10

    Novel nanostructured composite materials based on bacterial cellulose membranes (BC) and acrylate polymers were prepared by in situ atom transfer radical polymerization (ATRP). BC membranes were functionalized with initiating sites, by reaction with 2-bromoisobutyryl bromide (BiBBr), followed by atom transfer radical polymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA), catalyzed by copper(I) bromide and N,N,N',N?,N?-pentamethyldiethylenetriamine (PMDETA), using two distinct initiator amounts and monomer feeds. The living characteristic of the system was proven by the growth of PBA block from the BC-g-PMMA membrane. The BC nanofiber sleeving was clearly demonstrated by SEM imaging, and its extent can be tuned by controlling the amount of initiating sites and the monomer feed. The ensuing nanocomposites showed high hydrophobicity (contact angles with water up to 134°), good thermal stability (initial degradation temperature in the range 241-275 °C), and were more flexible that the unmodified BC membranes. PMID:23692287

  7. Bioactivity and structural properties of nanostructured bulk composites containing Nb2O5 and natural hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Bonadio, T. G. M.; Sato, F.; Medina, A. N.; Weinand, W. R.; Baesso, M. L.; Lima, W. M.

    2013-06-01

    In this work, we investigate the bioactivity and structural properties of nanostructured bulk composites that are composed of Nb2O5 and natural hydroxyapatite (HAp) and are produced by mechanical alloying and powder metallurgy. X-ray diffraction and Raman spectroscopy data showed that the milling process followed by a heat treatment at 1000 °C induced chemical reactions along with the formation of the CaNb2O6, PNb9O25 and Ca3(PO4)2 phases. Rietveld refinement indicated significant changes in each phase weight fraction as a function of HAp concentration. These changes influenced the in vitro bioactivity of the material. XRD and FTIR analyses indicated that the composites exhibited bioactivity characteristics by forming a carbonated apatite layer when the composites were immersed in a simulated body fluid. The formed layers had a maximum thickness of 13 ?m, as measured by confocal Raman spectroscopy and as confirmed by scanning electron microscopy. The results of this work suggest that the tested bulk composites are promising biomaterials for use in implants.

  8. Nanostructured Composite Electrodes for Lithium Batteries (Final Technical Report)

    SciTech Connect

    Meilin Liu, James Gole

    2006-12-14

    The objective of this study was to explore new ways to create nanostructured electrodes for rechargeable lithium batteries. Of particular interests are unique nanostructures created by electrochemical deposition, etching and combustion chemical vapor deposition (CCVD). Three-dimensional nanoporous Cu6Sn5 alloy has been successfully prepared using an electrochemical co-deposition process. The walls of the foam structure are highly-porous and consist of numerous small grains. This represents a novel way of creating porous structures that allow not only fast transport of gas and liquid but also rapid electrochemical reactions due to high surface area. The Cu6Sn5 samples display a reversible capacity of {approx}400 mAhg-1. Furthermore, these materials exhibit superior rate capability. At a current drain of 10 mA/cm2(20C rate), the obtainable capacity was more than 50% of the capacity at 0.5 mA/cm2 (1C rate). Highly open and porous SnO2 thin films with columnar structure were obtained on Si/SiO2/Au substrates by CCVD. The thickness was readily controlled by the deposition time, varying from 1 to 5 microns. The columnar grains were covered by nanoparticles less than 20 nm. These thin film electrodes exhibited substantially high specific capacity. The reversible specific capacity of {approx}3.3 mAH/cm2 was demonstrated for up to 80 cycles at a charge/discharge rate of 0.3 mA/cm2. When discharged at 0.9 mA/cm2, the capacity was about 2.1 mAH/cm2. Tin dioxide box beams or tubes with square or rectangular cross sections were synthesized using CCVD. The cross-sectional width of the SnO2 tubules was tunable from 50 nm to sub-micrometer depending on synthesis temperature. The tubes are readily aligned in the direction perpendicular to the substrate surface to form tube arrays. Silicon wafers were electrochemically etched to produce porous silicon (PS) with honeycomb-type channels and nanoporous walls. The diameters of the channels are about 1 to 3 microns and the depth of the channels can be up to 100 microns. We have successfully used the PS as a matrix for Si-Li-based alloy. Other component(s) can be incorporated into the PS either by an electroless metallization or by kinetically controlled vapor deposition.

  9. Thermoelectric figure of merit for bulk nanostructured composites with distributed parameters

    SciTech Connect

    Snarskii, A. A. [National Technical University 'Kyiv Polytechnic Institute' (Ukraine); Sarychev, A. K. [Russian Academy of Sciences, Institute for Theoretical and Applied Electromagnetics (Russian Federation); Bezsudnov, I. V., E-mail: biv@akuan.ru ['Nauka-Service' Scientific and Production Company (Russian Federation); Lagarkov, A. N. [Russian Academy of Sciences, Institute for Theoretical and Applied Electromagnetics (Russian Federation)

    2012-05-15

    The effective properties of composites whose structure includes nanocontacts between bulk-phase macrocrystallites are considered. A model for such a nanostructured composite is constructed. Effective values of the thermoelectric power, thermal and electrical conductivities, and thermoelectric figure of merit are calculated in the mean-field approximation.

  10. Efficient and versatile fibrous adsorbent based on magnetic amphiphilic composites of chrysotile/carbon nanostructures for the removal of ethynilestradiol.

    PubMed

    Teixeira, Ana Paula C; Purceno, Aluir D; de Paula, Camila C A; da Silva, Julio César C; Ardisson, José D; Lago, Rochel M

    2013-03-15

    In this work, chrysotile was used as support to grow carbon nanotubes and nanofibers to produce fibrous amphiphilic magnetic nanostructured composites. Iron impregnated on the chrysotile surface at 1, 5 and 15 wt% was used as catalyst to grow carbon nanostructures by CVD (chemical vapor deposition) with ethanol at 800°C. Raman, TG/DTA, Mössbauer, XRD, BET, SEM, TEM, elemental analyses and contact angle measurements suggested the formation of a complex amphiphilic material containing up to 21% of nanostructured hydrophobic carbon supported on hydrophilic Mg silicate fibers with magnetic Fe cores protected by carbon coating. Adsorption tests for the hormone ethynilestradiol (EE), a hazardous water contaminant, showed remarkable adsorption capacities even compared to high surface area activated carbon and multiwall carbon nanotubes. These results are discussed in terms of the hydrophobic surface of the carbon nanotubes and nanofibers completely exposed and accessible for the adsorption of the EE molecules combined with the hydrophilic Mg silicate surface which allows good dispersion in water. The composites are magnetic and after adsorption the dispersed particles can be removed by a simple magnetic process. Moreover, the fibrous composites can be conformed as threads, screens and pellets to produce different filtering media. PMID:23399907

  11. Aeroelastic tailoring of composite materials 

    E-print Network

    Rogers, Jesse Byron

    1979-01-01

    LIST OF FIGURES IiiTRODUCTI ON ST!!UCTURAL RESPONSE Deformation of Uniformly Stressed Isotropic and Anisotropic Plates Characterization of Composite Laminates . Effect of Material Parameters APPLICATIONS Aircraft Propellers Ship Propell rs... com- pliances with laminate rotation 39 15 Variation of (A) extensional ard (8) bending compliances with 0' ply rotation . . . . . . . . . . . . . . . . 40 16 Incremental aerodynamic forces on a typical blade element 43 17 Propeller velocity...

  12. Development of nanostructured biocompatible materials for chemical and biological sensors

    NASA Astrophysics Data System (ADS)

    Curley, Michael; Chilvery, Ashwith K.; Kukhatreva, Tatiana; Sharma, Anup; Corda, John; Farley, Carlton

    2012-10-01

    This research is focused on the fabrication of thin films followed by Surface Enhanced Raman Spectroscopy (SERS) testing of these films for various applications. One technique involves the mixture of nanoparticles with twophoton material to be used as an indicator dye. Another method involved embedding silver nanoparticles in a ceramic nano-membrane. The substrates were characterized by both Atom Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). We applied the nanostructured substrate to measure the SERS spectra of 10-6 Mol/L Rhodomine 6G(Rh6G), e-coli bacteria and RDX explosive. Our results showed that silver coated ceramic membranes can serve as appropriate substrates to enhance Raman signals. In addition, we demonstrated that the in-house-made colloidal silver can work for enhancement of the Raman spectra for bacteria. We measured the Raman spectra of Rh6G molecules on a substrate absorbed by a nanofluid of silver. We observed several strong Raman bands - 613cm-1,768 cm-1,1308cm-1 1356 cm-1,1510cm-1, which correspond to Rh6G vibrational modes ?53,?65,?115,?117,?146 respectively, using a ceramic membrane coated by silver. The Raman spectra of Rh6G absorbed by silver nanofluid showed strong enhancement of Raman bands 1175cm-1 and 1529cm-1, 1590 cm-1. Those correspond to vibrational frequency modes - ?103,?151,152. We also measured the Raman spectra of e-coli bacteria, both absorbed by silver nanofluid, and on nanostructured substrate. In addition, the Fourier Transfer Infrared Spectra (FTIR) of the bacteria was measured.

  13. Single-Molecule Investigations of Morphology and Mass Transport Dynamics in Nanostructured Materials.

    PubMed

    Higgins, Daniel A; Park, Seok Chan; Tran-Ba, Khanh-Hoa; Ito, Takashi

    2015-07-22

    Nanostructured materials such as mesoporous metal oxides and phase-separated block copolymers form the basis for new monolith, membrane, and thin film technologies having applications in energy storage, chemical catalysis, and separations. Mass transport plays an integral role in governing the application-specific performance characteristics of many such materials. The majority of methods employed in their characterization provide only ensemble data, often masking the nanoscale, molecular-level details of materials morphology and mass transport. Single-molecule fluorescence methods offer direct routes to probing these characteristics on a single-molecule/single-nanostructure basis. This article provides a review of single-molecule studies focused on measurements of anisotropic diffusion, adsorption, partitioning, and confinement in nanostructured materials. Experimental methods covered include confocal and wide-field fluorescence microscopy. The results obtained promise to deepen our understanding of mass transport mechanisms in nanostructures, thus aiding in the realization of advanced materials systems. PMID:26132347

  14. Improved Silica Aerogel Composite Materials

    NASA Technical Reports Server (NTRS)

    Paik, Jong-Ah; Sakamoto, Jeffrey; Jones, Steven

    2008-01-01

    A family of aerogel-matrix composite materials having thermal-stability and mechanical- integrity properties better than those of neat aerogels has been developed. Aerogels are known to be excellent thermal- and acoustic-insulation materials because of their molecular-scale porosity, but heretofore, the use of aerogels has been inhibited by two factors: (1) Their brittleness makes processing and handling difficult. (2) They shrink during production and shrink more when heated to high temperatures during use. The shrinkage and the consequent cracking make it difficult to use them to encapsulate objects in thermal-insulation materials. The underlying concept of aerogel-matrix composites is not new; the novelty of the present family of materials lies in formulations and processes that result in superior properties, which include (1) much less shrinkage during a supercritical-drying process employed in producing a typical aerogel, (2) much less shrinkage during exposure to high temperatures, and (3) as a result of the reduction in shrinkage, much less or even no cracking.

  15. Nanostructured materials with biomimetic recognition abilities for chemical sensing

    NASA Astrophysics Data System (ADS)

    Bajwa, Sadia Zafar; Mustafa, Ghulam; Samardzic, Renata; Wangchareansak, Thipvaree; Lieberzeit, Peter A.

    2012-06-01

    Binding features found in biological systems can be implemented into man-made materials to design nanostructured artificial receptor matrices which are suitable, e.g., for chemical sensing applications. A range of different non-covalent interactions can be utilized based on the chemical properties of the respective analyte. One example is the formation of coordinative bonds between a polymerizable ligand (e.g., N-vinyl-2-pyrrolidone) and a metal ion (e.g., Cu(II)). Optimized molecularly imprinted sensor layers lead to selectivity factors of at least 2 compared to other bivalent ions. In the same way, H-bonds can be utilized for such sensing purposes, as shown in the case of Escherichia coli. The respective molecularly imprinted polymer leads to the selectivity factor of more than 5 between the W and B strains, respectively. Furthermore, nanoparticles with optimized Pearson hardness allow for designing sensors to detect organic thiols in air. The `harder' MoS2 yields only about 40% of the signals towards octane thiol as compared to the `softer' Cu2S. However, both materials strongly prefer molecules with -SH functionality over others, such as hydrocarbon chains. Finally, selectivity studies with wheat germ agglutinin (WGA) reveal that artificial receptors yield selectivities between WGA and bovine serum albumin that are only about a factor of 2 which is smaller than natural ligands.

  16. Dendrimer-modified solid supports: nanostructured materials with potential drug allergy diagnostic applications.

    PubMed

    Ruiz-Sanchez, A J; Montañez, M I; Mayorga, C; Torres, M J; Kehr, N S; Vida, Y; Collado, D; Najera, F; De Cola, L; Perez-Inestrosa, E

    2012-01-01

    Complex functional materials consisting of bioactive molecules immobilized on solid supports present potential applications in biosensoring. Advances in the fabrication of these surface materials are of growing interest for antibody-based diagnosis. This work exploits dendrimers as versatile nanostructures for templating sensor surfaces and the critical role of the immobilization protocol in the solid supports cellulose and zeolites, of organic and inorganic composition respectively. The fabrication and characterization, including the degree of functionalization and reproducibility, of different nanostructured materials are described. To validate the approach, the fabricated supports were further used as a solid phase for developing a radioimmunoassay to detect immunoglobulin E (IgE) specific to penicillin, the antibody involved in immediate allergy responses to this drug. The dendrimer-modified supports provide assays with significantly enhanced sensitivity, as well as increase the availability of biomolecules for specific interaction and minimize nonspecific adsorptions through appropriate functionalization protocols in each case. The manufacturing methodology involved the use of a long, flexible hydrophilic spacer in the cellulose materials, and a higher surface density of the immobilized dendrimers in the zeolite crystals. The ability of hybrid zeolite materials in such biosensing applications was evaluated for the first time. The assays were validated in human serum samples from patients allergic to penicillin and from non-allergic controls. The specificity and improved sensitivity of the dendrimer- modified supports make these strategies versatile for different bioactive molecules and could have significant implications for the quantification of a wide range of specific IgE antibodies and other biomolecules of diagnostic interest. PMID:22963628

  17. Properties of composite materials for cryogenic applications

    Microsoft Academic Search

    J. B Schutz

    1998-01-01

    Composite materials are used in a wide variety of cryogenic applications because of their unique and highly tailorable properties. These cryogenic applications of composites may be, for the sake of discussion, classified as support structures, vessels, or electrical insulation. Examples of these applications are presented, with a brief discussion of the critical material properties associated with each application. Composite material

  18. ULTRASONIC CHARACTERIZATION OF ADVANCED COMPOSITE MATERIALS

    Microsoft Academic Search

    B. Boro Djordjevic

    With increased use of composite materials in critical structural applications it is more important than ever to independently assure structural integrity. Complexity of the advanced composite materials including layered and bonded structures represents challenges in developing optimized ultrasonic tests. Traditional ultrasonic NDT methods are inappropriate and often misleading when applied to anisotropic and nonhomogeneous composite materials. In advanced technology applications

  19. Nanostructured Graphene-Titanium Dioxide Composites Synthesized by a Single-Step Aerosol Process for Photoreduction of Carbon Dioxide

    PubMed Central

    Wang, Wei-Ning; Jiang, Yi; Fortner, John D.; Biswas, Pratim

    2014-01-01

    Abstract Photocatalytic reduction of carbon dioxide (CO2) to hydrocarbons by using nanostructured materials activated by solar energy is a promising approach to recycling CO2 as a fuel feedstock. CO2 photoreduction, however, suffers from low efficiency mainly due to the inherent drawback of fast electron-hole recombination in photocatalysts. This work reports the synthesis of nanostructured composites of titania (TiO2) nanoparticles (NPs) encapsulated by reduced graphene oxide (rGO) nanosheets via an aerosol approach. The role of synthesis temperature and TiO2/GO ratio in CO2 photoreduction was investigated. As-prepared nanocomposites demonstrated enhanced CO2 conversion performance as compared with that of pristine TiO2 NPs due to the strong electron trapping capability of the rGO nanosheets. PMID:25053879

  20. Nanostructured Graphene-Titanium Dioxide Composites Synthesized by a Single-Step Aerosol Process for Photoreduction of Carbon Dioxide.

    PubMed

    Wang, Wei-Ning; Jiang, Yi; Fortner, John D; Biswas, Pratim

    2014-07-01

    Photocatalytic reduction of carbon dioxide (CO2) to hydrocarbons by using nanostructured materials activated by solar energy is a promising approach to recycling CO2 as a fuel feedstock. CO2 photoreduction, however, suffers from low efficiency mainly due to the inherent drawback of fast electron-hole recombination in photocatalysts. This work reports the synthesis of nanostructured composites of titania (TiO2) nanoparticles (NPs) encapsulated by reduced graphene oxide (rGO) nanosheets via an aerosol approach. The role of synthesis temperature and TiO2/GO ratio in CO2 photoreduction was investigated. As-prepared nanocomposites demonstrated enhanced CO2 conversion performance as compared with that of pristine TiO2 NPs due to the strong electron trapping capability of the rGO nanosheets. PMID:25053879

  1. Thermal stability and proton conductivity of silane based nanostructured composite membranes

    Microsoft Academic Search

    R. N. Jana; H. Bhunia

    2008-01-01

    A series of silane based nanostructured composite membranes were synthesized from 3-glycidoxy propyl trimethoxy silane (GPTMS) and 2(3, 4 epoxy cyclohexyl) ethyl triethoxy silane (EHTES) with varying proportion of aqueous orthophosphoric acid, nanoclay (Cloisite® 30B) and multi-walled carbon nanotubes (MWNTs) by sol–gel method. Thermal stability of the composite membranes studied by thermogravimetric analysis (TGA) showed that the composite membranes were

  2. Nonintrusive interfacial characterization of advanced composite materials

    Microsoft Academic Search

    Renee M. Kent

    1995-01-01

    It is well known that the fiber matrix interface plays the dominant role in the mechanical behavior of advanced composite materials. Engineering and control of the interface is paramount to producing the properties for desired mechanical performance of the ultimate composite structure. This is particularly critical for advanced composites (metal matrix composites, ceramic matrix composites) which are currently being investigated

  3. An Experimental Study of Deformation and Fracture of a Nanostructured Metallic Material 

    E-print Network

    Abdel Al, Nisrin Rizek

    2011-02-22

    capacity, thus favoring flow localization and loss of ductility and toughness. The deformation behavior of nanostructured metallic materials has been extensively studied in the literature. However, little is known of their fracture behavior. In this study...

  4. Methods for high volume production of nanostructured materials

    DOEpatents

    Ripley, Edward B. (Knoxville, TN); Morrell, Jonathan S. (Knoxville, TN); Seals, Roland D. (Oak Ridge, TN); Ludtka, Gerald M. (Oak Ridge, TN)

    2011-03-22

    A system and method for high volume production of nanoparticles, nanotubes, and items incorporating nanoparticles and nanotubes. Microwave, radio frequency, or infrared energy vaporizes a metal catalyst which, as it condenses, is contacted by carbon or other elements such as silicon, germanium, or boron to form agglomerates. The agglomerates may be annealed to accelerate the production of nanotubes. Magnetic or electric fields may be used to align the nanotubes during their production. The nanotubes may be separated from the production byproducts in aligned or non-aligned configurations. The agglomerates may be formed directly into tools, optionally in compositions that incorporate other materials such as abrasives, binders, carbon-carbon composites, and cermets.

  5. Covalent functionalization of metal oxide and carbon nanostructures with polyoctasilsesquioxane (POSS) and their incorporation in polymer composites

    SciTech Connect

    Gomathi, A.; Gopalakrishnan, K. [Chemistry and Physics of Materials Unit, New Chemistry Unit and CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560 064 (India)] [Chemistry and Physics of Materials Unit, New Chemistry Unit and CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560 064 (India); Rao, C.N.R., E-mail: cnrrao@jncasr.ac.in [Chemistry and Physics of Materials Unit, New Chemistry Unit and CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560 064 (India)] [Chemistry and Physics of Materials Unit, New Chemistry Unit and CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560 064 (India)

    2010-12-15

    Polyoctasilsesquioxane (POSS) has been employed to covalently functionalize nanostructures of TiO{sub 2}, ZnO and Fe{sub 2}O{sub 3} as well as carbon nanotubes, nanodiamond and graphene to enable their dispersion in polar solvents. Covalent functionalization of these nanostructures with POSS has been established by electron microscopy, EDAX analysis and infrared spectroscopy. On heating the POSS-functionalized nanostructures, silica-coated nanostructures are obtained. POSS-functionalized nanoparticles of TiO{sub 2}, Fe{sub 2}O{sub 3} and graphite were utilized to prepare polymer-nanostructure composites based on PVA and nylon-6,6.

  6. Effects of irradiation on the microstructure and mechanical properties of nanostructured materials

    Microsoft Academic Search

    N. Nita; R. Schaeublin; M. Victoria; R. Z. Valiev

    2005-01-01

    Nanostructured materials should present a good resistance to irradiation because the large volume fraction of grain boundaries can be an important sink for radiation-induced defects. The objective of the present study is to experimentally investigate the irradiation impact on the microstructure and mechanical properties in nanostructured materials.Nickel and Cu-0.5Al2O3 specimens were synthesized by electro deposition (ED) and severe plastic deformation

  7. Enhancing thermoelectric properties of organic composites through hierarchical nanostructures.

    PubMed

    Zhang, Kun; Zhang, Yue; Wang, Shiren

    2013-01-01

    Organic thermoelectric (TE) materials are very attractive due to easy processing, material abundance, and environmentally-benign characteristics, but their potential is significantly restricted by the inferior thermoelectric properties. In this work, noncovalently functionalized graphene with fullerene by ?-? stacking in a liquid-liquid interface was integrated into poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate). Graphene helps to improve electrical conductivity while fullerene enhances the Seebeck coefficient and hinders thermal conductivity, resulting in the synergistic effect on enhancing thermoelectric properties. With the integration of nanohybrids, the electrical conductivity increased from ~10,000 to ~70,000?S/m, the thermal conductivity changed from 0.2 to 2?W·K(-1)m(-1) while the Seebeck coefficient was enhanced by around 4-fold. As a result, nanohybrids-based polymer composites demonstrated the figure of merit (ZT) as high as 6.7 × 10(-2), indicating an enhancement of more than one order of magnitude in comparison to single-phase filler-based polymer composites with ZT at the level of 10(-3). PMID:24336319

  8. Supramolecular chirality in self-assembled soft materials: regulation of chiral nanostructures and chiral functions.

    PubMed

    Zhang, Li; Qin, Long; Wang, Xiufeng; Cao, Hai; Liu, Minghua

    2014-10-29

    Supramolecular chirality, which arises from the nonsymmetric spatial arrangement of components in the self-assembly systems, has gained great attention owing to its relation to the natural biological structures and the possible new functions in advanced materials. During the self-assembling process, both chiral and achiral components are possible to form chiral nanostructures. Therefore, it becomes an important issue how to fabricate these molecular components into chiral nanostructures. Furthermore, once the chiral nanostructure is obtained, will it show new functions that simple component molecule could not? In this research news, we report our recent development in the regulation of chiral nanostructures in soft gels or vesicle materials. We have further developed several new functions pertaining to the soft gel materials, which single chiral molecules could not perform, such as the chiroptical switch, chiral recognition and the asymmetry catalysis. PMID:24687217

  9. Composite material heat pipe radiator

    NASA Astrophysics Data System (ADS)

    Gernert, Nelson J.; Sarraf, David B.; Guenther, Richard J.; Hurlbert/, Kathryn Miller

    1996-03-01

    Organic matrix composite material is recognized for its significant strength to weight ratio when compared to metal and consequently was investigated for reducing the mass of heat pipes for future space missions. The particular heat pipe that was constructed and tested was made from an organic matrix composite material applied to a linear of titanium tubing spun to foil thickness (0.076 mm). The thin liner transitioned to heavier-walled ends which allowed the tubing to be sealed using conventional welding. More specifically, the heat pipe was 1.14 m long, 24 mm in diameter and had a mass of 0.165 kg. Water was the working fluid. The heat pipe was tested in a Thermacore thermal vacuum chamber under hot and cold wall operating conditions. The heat load dissipated ranged from 10 to 60 watts. Heat pipe operating temperatures varied from 278 K to 403 K. After testing, the heat pipe was delivered to NASA JSC where future thermal vacuum chamber tests are planned.

  10. Tuning energy transport in solar thermal systems using nanostructured materials

    E-print Network

    Lenert, Andrej

    2014-01-01

    Solar thermal energy conversion can harness the entire solar spectrum and theoretically achieve very high efficiencies while interfacing with thermal storage or back-up systems for dispatchable power generation. Nanostructured ...

  11. Morphology and composition controlled synthesis of flower-like silver nanostructures

    PubMed Central

    2014-01-01

    Flower-like silver nanostructures with controlled morphology and composition were prepared through wet-chemical synthesis. The reaction rate is simply manipulated by the amount of catalyzing agent ammonia added which is the key point to determine the ratio of hexagonal close-packed (HCP) to face-centered cubic (FCC) phase in silver nanostructures. The existence of formic acid that is the oxidation product of aldehyde group is demonstrated to play a crucial role in achieving the metastable HCP crystal structures by replacing ionic surfactants with polyvinylpyrrolidone (PVP). Utilizing flower-like silver nanostructures as surface-enhanced Raman scattering (SERS) substrates, Raman signal of Rhodamine 6G, or 4-aminothiophenol with concentration as low as 10?7 M was detected. Moreover, it is demonstrated that phase composition has no direct relation to the SERS enhancing factor which is mainly determined by the amount of hot spots. PMID:24994957

  12. Morphology and composition controlled synthesis of flower-like silver nanostructures

    NASA Astrophysics Data System (ADS)

    Zhou, Ning; Li, Dongsheng; Yang, Deren

    2014-06-01

    Flower-like silver nanostructures with controlled morphology and composition were prepared through wet-chemical synthesis. The reaction rate is simply manipulated by the amount of catalyzing agent ammonia added which is the key point to determine the ratio of hexagonal close-packed (HCP) to face-centered cubic (FCC) phase in silver nanostructures. The existence of formic acid that is the oxidation product of aldehyde group is demonstrated to play a crucial role in achieving the metastable HCP crystal structures by replacing ionic surfactants with polyvinylpyrrolidone (PVP). Utilizing flower-like silver nanostructures as surface-enhanced Raman scattering (SERS) substrates, Raman signal of Rhodamine 6G, or 4-aminothiophenol with concentration as low as 10-7 M was detected. Moreover, it is demonstrated that phase composition has no direct relation to the SERS enhancing factor which is mainly determined by the amount of hot spots.

  13. Nano-structured composite cathodes for intermediate temperature solid oxide fuel cells via an infiltration/impregnation technique

    SciTech Connect

    Jiang, Zhiyi; Xia, Changrong; Chen, Fanglin

    2010-04-01

    Solid oxide fuel cells (SOFCs) are high temperature energy conversion devices working efficiently and environmental friendly. SOFC requires a functional cathode with high electrocatalytic activity for the electrochemical reduction of oxygen. The electrode is often fabricated at high temperature to achieve good bonding between the electrode and electrolyte. The high temperature not only limits material choice but also results in coarse particles with low electrocatalytic activity. Nano-structured electrodes fabricated at low temperature by an infiltration/impregnation technique have shown many advantages including superior activity and wider range of material choices. The impregnation technique involves depositing nanoparticle catalysts into a pre-sintered electrode backbone. Two basic types of nano-structures are developed since the electrode is usually a composite consists of an electrolyte and an electrocatalyst. One is infiltrating electronically conducting nano-catalyst into a single phase ionic conducting backbone, while the other is infiltrating ionically conducting nanoparticles into a single phase electronically conducting backbone. In addition, nanoparticles of the electrocatalyst, electrolyte and other oxides have also been infiltrated into mixed conducting backbones. These nano-structured cathodes are reviewed here regarding the preparation methods, their electrochemical performance, and stability upon thermal cycling.

  14. Phase composition, structure, and properties of aluminum materials mechanically alloyed with boron

    Microsoft Academic Search

    G. F. Lovshenko; F. G. Lovshenko

    2007-01-01

    The paper focuses on the formation of phase composition, structure, and properties of high-strength aluminum materials that\\u000a are mechanically alloyed with boron and have a large effective thermal-neutron capture cross-section. A technology based on\\u000a reactive mechanical alloying is proposed. It is intended to produce dispersion-hardened nanostructured materials in the Al-B\\u000a system. Structural high-temperature materials with a low density and a

  15. Modeling and characterization of the elastic behavior of interfaces in nanostructured materials: From an atomistic description to a continuum approach

    NASA Astrophysics Data System (ADS)

    Dingreville, Remi

    Steady technological progresses in all fields of nanoscale technology and probe technology have enabled the synthesis, the assembly, the development, the characterization and the improvement of nanostructured materials. The lack of understanding of their macroscopic behavior is a major roadblock for inserting these materials into engineering applications. Partially due to these rapid advances in nano-scale and nano-structured materials, there has been a resurgence of interest in surface elastic properties such as surface energy, surface stresses, and surface elastic stiffness. Because of the large surface-to-volume ratio in nano-materials, surface elastic properties become more prominent. They have strong influence on the overall thermo-mechanical behavior of the nano-materials. In this dissertation, an innovative approach combining continuum mechanics and atomistic simulations is exposed to develop a nanomechanics theory for modeling and predicting the macroscopic behavior of nanomaterials. This nanomechanics theory exhibits the simplicity of the continuum formulation while taking into account the discrete atomic structure and interaction near surfaces/interfaces. There are four primary objectives to this dissertation. First, theory of interfaces is revisited to better understand its behavior and effects on the overall behavior of nanostructures. Second, atomistic tools are provided in order to efficiently determine the properties of free surfaces and interfaces. Interface properties are reported in this work, with comparison to both theoretical and experimental characterizations of interfaces. Specifically, we report surface elastic properties of groups 10--11 transition metals as well as properties for low-CSL grain boundaries in copper. Third, we propose a continuum framework that casts the atomic level information into continuum quantities that can be used to analyze, model and simulate macroscopic behavior of nanostructured materials. In particular, we study the effects of surface free energy on the effective modulus of nano-particles, nano-wires and nano-films as well as nanostructured crystalline materials and propose a general framework valid for any shape of nanostructural elements/nano-inclusions (integral forms) that characterizes the size-dependency of the elastic properties. This approach bridges the gap between discrete systems (atomic level interactions) and continuum mechanics. Finally this continuum outline is used to understand the effects of surfaces on the overall behavior of nano-size structural elements (particles, films, fibers, etc.) and nanostructured materials. More specifically we will discuss the impact of surface relaxation, surface elasticity and non-linearity of the underlying bulk on the properties nanostructured materials. In terms of engineering applications, this approach proves to be a useful tool for multi-scale modeling of heterogeneous materials with nanometer scale microstructures and provides insights on surface properties for several material systems; these will be very useful in many fields including surface science, tribology, fracture mechanics, adhesion science and engineering, and more. It will accelerate the insertion of nano-size structural elements, nano-composite and nanocrystalline materials into engineering applications.

  16. FEM analysis of spur gears forging from nano-structured materials

    NASA Astrophysics Data System (ADS)

    Salcedo, D.; Luis-Pérez, C. J.; Luri, R.; León, J.

    2012-04-01

    The ECAE process is a novel technology which allows us to obtain materials with sub-micrometric and/or nanometric grain size as a result of accumulating very high levels of plastic deformation in the presence of a high hydrostatic pressure. This avoids the fracture of the material and allows us to obtain very high values of plastic deformation (? >>1). Therefore, these nano-structured materials can be used as starting materials for other manufacturing processes such as: extrusion, rolling and forging, among others; with the advantage of providing nanostructure and hence, improved mechanical properties. In this present work, the forging by finite element method (FEM) of materials that have been previously processed by ECAE is analyzed. MSC. MarcTM software will be employed with the aim of analyzing the possibility of manufacturing mechanical components (spur gears) from materials nano-structured by ECAE.

  17. Theoretical analysis of electric, magnetic and magnetoelectric properties of nano-structured multiferroic composites

    Microsoft Academic Search

    Xiaoyan Lu; Hui Li; Biao Wang

    2011-01-01

    Electric, magnetic and magnetoelectric properties of the nano-structured multiferroic composites were studied by using an energy formulation with the consideration of the surface, interface, and size effect. Coupled thermodynamic evolution equations with respect to the spontaneous polarization and magnetization were established, in which the elastic fields in the matrix and inclusions were solved based on the Eshelby's equivalent inclusion concept

  18. Polyolefin composites containing a phase change material

    DOEpatents

    Salyer, Ival O. (Dayton, OH)

    1991-01-01

    A composite useful in thermal energy storage, said composite being formed of a polyolefin matrix having a phase change material such as a crystalline alkyl hydrocarbon incorporated therein, said polyolefin being thermally form stable; the composite is useful in forming pellets, sheets or fibers having thermal energy storage characteristics; methods for forming the composite are also disclosed.

  19. Vibrational Damping of Composite Materials

    E-print Network

    Biggerstaff, Janet M.

    2006-01-01

    polymeric composites composed of fibers (graphite, Kevlar,by Cape Composites, had intermediate modulus graphite fibersFiber and Resin on the Vibration Damping of Composites Reinforced wit Fiberglass, Graphite, and

  20. Near-field–induced tunability of surface plasmon polaritons in composite metallic nanostructures

    Microsoft Academic Search

    A. CHRIST; G. LÉVÊQUE; O. J. F. MARTIN; T. ZENTGRAF; J. KUHL; C. BAUER; H. GIESSEN; S. G. TIKHODEEV

    2008-01-01

    Summary We numerically study near-field-induced coupling effects in metal nanowire-based composite nanostructures. Our multi-layer system is composed of individual gold nanowires supporting localized particle plasmons at optical wavelengths, and a spatially separated homogeneous silver slab supporting delocalized surface plasmons. We show that the localized plasmon modes of the composite structure, forming so-called magnetic atoms, can be controlled over a large

  1. Reliable contact fabrication on nanostructured Bi2Te3-based thermoelectric materials.

    PubMed

    Feng, Shien-Ping; Chang, Ya-Huei; Yang, Jian; Poudel, Bed; Yu, Bo; Ren, Zhifeng; Chen, Gang

    2013-05-14

    A cost-effective and reliable Ni-Au contact on nanostructured Bi2Te3-based alloys for a solar thermoelectric generator (STEG) is reported. The use of MPS SAMs creates a strong covalent binding and more nucleation sites with even distribution for electroplating contact electrodes on nanostructured thermoelectric materials. A reliable high-performance flat-panel STEG can be obtained by using this new method. PMID:23531997

  2. Composite material and method of making

    DOEpatents

    Fryxell, Glen E.; Samuels, William D.; Simmons, Kevin L.

    2004-04-20

    The composite material and methods of making the present invention rely upon a fully dense monolayer of molecules attached to an oxygenated surface at one end, and an organic terminal group at the other end, which is in turn bonded to a polymer. Thus, the composite material is a second material chemically bonded to a polymer with fully dense monolayer there between.

  3. Nonlinear Dynamic Properties of Layered Composite Materials

    SciTech Connect

    Andrianov, Igor V.; Topol, Heiko; Weichert, Dieter [Institute of General Mechanics, RWTH Aachen University, Termplergraben 64, Aachen, D-52062 (Germany); Danishevs'kyy, Vladyslav V. [Prydniprovs'ka State Academy of Civil Engineering and Architecture, Dnipropetrovs'k, Chernishevs'kogo 24a, UA-49600 (Ukraine)

    2010-09-30

    We present an application of the asymptotic homogenization method to study wave propagation in a one-dimensional composite material consisting of a matrix material and coated inclusions. Physical nonlinearity is taken into account by considering the composite's components as a Murnaghan material, structural nonlinearity is caused by the bonding condition between the components.

  4. Design, fabrication, and testing of nanostructured carbons and composites

    NASA Astrophysics Data System (ADS)

    Wang, Zhiyong

    Many applications, such as catalysis, sensing, separation and energy storage and conversion, will benefit from the miniaturization of materials to nanometer length scales. This dissertation details my study of nanocomposites based on three-dimensionally ordered macroporous (3DOM) carbons and zirconia, and three-dimensionally ordered macroporous/mesoporous (3DOM/m) carbons. The macropores of these materials were produced using colloidal crystal templates while the mesopores were generated using surfactant templates. These solids are composed of close-packed and three-dimensionally interconnected spherical macropores surrounded by nanoscale solid or mesoporous wall skeletons. This unique architecture offers large surface areas, pore volumes, and good access into the bulk via a macroporous network. 3DOM carbons have been demonstrated as promising electrode materials for lithium ion batteries and sensors, but their electrochemical performance still needs to be improved. As a model system for the modification of the electrode, 3DOM C/TiO2 was synthesized by fabricating a conformal coating of TiO2 nanoparticles on the macropore walls of 3DOM C. My research further extended the micro-structural design of monolithic carbon from 3DOM to 3DOM/m. 3DOM/m C monoliths with high surface areas, controllable mesopore sizes, and mesopore ordering, were synthesized by three methods. One of the methods is simpler and more environment benign than previously reported methods. The mesopores in 3DOM/m C-based electrode provide room to accommodate secondary phases, such as graphitic carbon, SnO2 and Si which can improve the conductivity or lithium capacity of the electrode. Owing to this advantage, 3DOM/m C/C and 3DOM/m C/SnO2 exhibited significantly improved rate performance, lithium capacity and cycleability, compared with 3DOM C. To meet the demands of nano-sized functional materials in applications such as nano-device fabrication and drug delivery, mesoporous carbon nanoparticles with cubic, spherical and tetrapod shapes were also synthesized. In addition, new methods were developed to assemble nanocomposites of bifunctional catalyst components. These materials were designed for the potential direct conversion of synthesis gas to clean liquid fuels. Coatings of zeolite and cobalt nanoparticles were fabricated on 3DOM promoted zirconia. The 3DOM zirconia-based nanocomposites were characterized by a wide variety of techniques to illustrate their morphologies, internal structures, chemical compositions, porosity, and crystallographic phases.

  5. Resonant soft x-ray and extreme ultraviolet magnetic scattering in nanostructured magnetic materials: fundamentals and directions

    E-print Network

    Kortright, Jeffrey

    2014-01-01

    soft x-ray and extreme ultraviolet magnetic scattering in nanostructured magnetic materials:soft x-ray resonant scattering well-suited to study magnetic behavior in nanostructured materials,material systems. The ultimate utility of resonant soft x-ray magnetic

  6. Morphology and microstructure of composite materials

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Srinivansan, K.

    1991-01-01

    Lightweight continuous carbon fiber based polymeric composites are currently enjoying increasing acceptance as structural materials capable of replacing metals and alloys in load bearing applications. As with most new materials, these composites are undergoing trials with several competing processing techniques aimed at cost effectively producing void free consolidations with good mechanical properties. As metallic materials have been in use for several centuries, a considerable database exists on their morphology - microstructure; and the interrelationships between structure and properties have been well documented. Numerous studies on composites have established the crucial relationship between microstructure - morphology and properties. The various microstructural and morphological features of composite materials, particularly those accompanying different processing routes, are documented.

  7. Effect of interface structure on mechanical properties of advanced composite materials.

    PubMed

    Gan, Yong X

    2009-12-01

    This paper deals with the effect of interface structures on the mechanical properties of fiber reinforced composite materials. First, the background of research, development and applications on hybrid composite materials is introduced. Second, metal/polymer composite bonded structures are discussed. Then, the rationale is given for nanostructuring the interface in composite materials and structures by introducing nanoscale features such as nanopores and nanofibers. The effects of modifying matrices and nano-architecturing interfaces on the mechanical properties of nanocomposite materials are examined. A nonlinear damage model for characterizing the deformation behavior of polymeric nanocomposites is presented and the application of this model to carbon nanotube-reinforced and reactive graphite nanotube-reinforced epoxy composite materials is shown. PMID:20054466

  8. Effect of Interface Structure on Mechanical Properties of Advanced Composite Materials

    PubMed Central

    Gan, Yong X.

    2009-01-01

    This paper deals with the effect of interface structures on the mechanical properties of fiber reinforced composite materials. First, the background of research, development and applications on hybrid composite materials is introduced. Second, metal/polymer composite bonded structures are discussed. Then, the rationale is given for nanostructuring the interface in composite materials and structures by introducing nanoscale features such as nanopores and nanofibers. The effects of modifying matrices and nano-architecturing interfaces on the mechanical properties of nanocomposite materials are examined. A nonlinear damage model for characterizing the deformation behavior of polymeric nanocomposites is presented and the application of this model to carbon nanotube-reinforced and reactive graphite nanotube-reinforced epoxy composite materials is shown. PMID:20054466

  9. Composite structural materials. [fiber reinforced composites for aircraft structures

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberly, S. E.

    1981-01-01

    Physical properties of fiber reinforced composites; structural concepts and analysis; manufacturing; reliability; and life prediction are subjects of research conducted to determine the long term integrity of composite aircraft structures under conditions pertinent to service use. Progress is reported in (1) characterizing homogeneity in composite materials; (2) developing methods for analyzing composite materials; (3) studying fatigue in composite materials; (4) determining the temperature and moisture effects on the mechanical properties of laminates; (5) numerically analyzing moisture effects; (6) numerically analyzing the micromechanics of composite fracture; (7) constructing the 727 elevator attachment rib; (8) developing the L-1011 engine drag strut (CAPCOMP 2 program); (9) analyzing mechanical joints in composites; (10) developing computer software; and (11) processing science and technology, with emphasis on the sailplane project.

  10. NASA technology utilization survey on composite materials

    NASA Technical Reports Server (NTRS)

    Leeds, M. A.; Schwartz, S.; Holm, G. J.; Krainess, A. M.; Wykes, D. M.; Delzell, M. T.; Veazie, W. H., Jr.

    1972-01-01

    NASA and NASA-funded contractor contributions to the field of composite materials are surveyed. Existing and potential non-aerospace applications of the newer composite materials are emphasized. Economic factors for selection of a composite for a particular application are weight savings, performance (high strength, high elastic modulus, low coefficient of expansion, heat resistance, corrosion resistance,), longer service life, and reduced maintenance. Applications for composites in agriculture, chemical and petrochemical industries, construction, consumer goods, machinery, power generation and distribution, transportation, biomedicine, and safety are presented. With the continuing trend toward further cost reductions, composites warrant consideration in a wide range of non-aerospace applications. Composite materials discussed include filamentary reinforced materials, laminates, multiphase alloys, solid multiphase lubricants, and multiphase ceramics. New processes developed to aid in fabrication of composites are given.

  11. Self-Assembly and Headgroup Effect in Nanostructured Organogels via Cationic Amphiphile-Graphene Oxide Composites

    PubMed Central

    Jiao, Tifeng; Wang, Yujin; Zhang, Qingrui; Yan, Xuehai; Zhao, Xiaoqing; Zhou, Jingxin; Gao, Faming

    2014-01-01

    Self-assembly of hierarchical graphene oxide (GO)-based nanomaterials with novel functions has received a great deal of attentions. In this study, nanostructured organogels based on cationic amphiphile-GO composites were prepared. The gelation behaviors of amphiphile-GO composites in organic solvents can be regulated by changing the headgroups of amphiphiles. Ammonium substituted headgroup in molecular structures in present self-assembled composites is more favorable for the gelation in comparison to pyridinium headgroup. A possible mechanism for headgroup effects on self-assembly and as-prepared nanostructures is proposed. It is believed that the present amphiphile-GO self-assembled system will provide an alternative platform for the design of new GO nanomaterials and soft matters. PMID:24983466

  12. Band modulation and in-plane propagation of surface plasmons in composite nanostructures

    NASA Astrophysics Data System (ADS)

    Fan, Ren-Hao; Xu, Di-Hu; Zhang, Kun; Peng, Ru-Wen; Wang, Mu

    2015-03-01

    In this work, we have experimentally and theoretically studied band modulation and in-plane propagation of surface plasmons (SPs) in composite nanostructures with aperture arrays and metallic gratings. It is shown that the plasmonic band structure of the composite system can be significantly modulated because of coupling between the aperture and the grating. By changing the relative positions between these optical components, the resonant modes would shift or split. And the resonant SP modes launched on the structure surface can be effectively modified by the geometric parameters. Further, we provide an experimental observation to directly show the SP in-plane propagation by using far-field measurements. Our study offers a convenient way for observing the SP propagation in far field, and provides unique composite nanostructures for possible applications in subwavelength optodevices, such as optical sensors and detectors.

  13. Wave propagation and impact in composite materials

    NASA Technical Reports Server (NTRS)

    Moon, F. C.

    1975-01-01

    Anisotropic waves in composites are considered, taking into account wave speeds, wave surfaces, flexural waves in orthotropic plates, surface waves, edge waves in plates, and waves in coupled composite plates. Aspects of dispersion in composites are discussed, giving attention to pulse propagation and dispersion, dispersion in rods and plates, dispersion in a layered composite, combined material and structural dispersion, continuum theories for composites, and variational methods for periodic composites. The characteristics of attenuation and scattering processes are examined and a description is given of shock waves and impact problems in composites. A number of experiments are also reported.

  14. Author's Accepted Manuscript Hybrid nanostructured materials for high-

    E-print Network

    Cui, Yi

    nanomaterials; nanostructures; energy storage; pseudocapacitive; supercapacitors #12;2 Abstract: The exciting polymers for achieving high-performance ECs. This review starts with an overview of EES technologies nanomaterials and novel support structures for effective electrochemical utilization and high mass loading

  15. Engineering of nanostructured carbon materials with electron or ion beams

    Microsoft Academic Search

    A. V. Krasheninnikov; F. Banhart

    2007-01-01

    Irradiating solids with energetic particles is usually thought to introduce disorder, normally an undesirable phenomenon. But recent experiments on electron or ion irradiation of various nanostructures demonstrate that it can have beneficial effects and that electron or ion beams may be used to tailor the structure and properties of nanosystems with high precision. Moreover, in many cases irradiation can lead

  16. Nanostructured materials for lithium-ion batteries: Surface conductivity vs. bulk

    E-print Network

    Ryan, Dominic

    Nanostructured materials for lithium-ion batteries: Surface conductivity vs. bulk ion cathode materials for high capacity lithium-ion batteries. Owing to their inherently low electronic framework structures that host mobile interstitial Li+ ions is crucial in developing high capacity lithium-ion

  17. Switching of the natural nanostructure in Bi2Te3 materials by ion irradiation.

    PubMed

    Aabdin, Zainul; Peranio, Nicola; Eibl, Oliver

    2012-09-01

    In Bi(2)Te(3) materials the natural nanostructure (nns) with a wavelength of 10 nm can be reproducibly switched ON and OFF by Ar(+) ion irradiation at 1.5 and 1 keV. Controlled formation of the nns in Bi(2)Te(3) materials has potential for reducing its thermal conductivity and could increase the thermoelectric figure of merit. PMID:22718358

  18. Nanostructured thermoelectrics based on periodic composites from opals and opal replicas. I. Bi-infiltrated opals

    Microsoft Academic Search

    R. H. Baughman; A. A. Zakhidov; I. I. Khayrullin; I. A. Udod; C. Cui; G. U. Sumanasekera; L. Grigorian; P. C. Eklund; V. Browning; A. Ehrlich

    1998-01-01

    We have developed a variety of templating processes for the fabrication of three-dimensionally periodic, nanostructured thermoelectrics from opal and inverse opal matrices. These opals and inverse opals are periodic at optical wavelengths and have extremely high interfacial area. It was hoped that scattering processes at the interface between opal and infiltrated thermoelectric material would increase the thermoelectric figure of merit

  19. Clues for biomimetics from natural composite materials

    PubMed Central

    Lapidot, Shaul; Meirovitch, Sigal; Sharon, Sigal; Heyman, Arnon; Kaplan, David L; Shoseyov, Oded

    2013-01-01

    Bio-inspired material systems are derived from different living organisms such as plants, arthropods, mammals and marine organisms. These biomaterial systems from nature are always present in the form of composites, with molecular-scale interactions optimized to direct functional features. With interest in replacing synthetic materials with natural materials due to biocompatibility, sustainability and green chemistry issues, it is important to understand the molecular structure and chemistry of the raw component materials to also learn from their natural engineering, interfaces and interactions leading to durable and highly functional material architectures. This review will focus on applications of biomaterials in single material forms, as well as biomimetic composites inspired by natural organizational features. Examples of different natural composite systems will be described, followed by implementation of the principles underlying their composite organization into artificial bio-inspired systems for materials with new functional features for future medicine. PMID:22994958

  20. Composite materials and method of making

    DOEpatents

    Simmons, Kevin L [Kennewick, WA; Wood, Geoffrey M [North Saanich, CA

    2011-05-17

    A method for forming improved composite materials using a thermosetting polyester urethane hybrid resin, a closed cavity mold having an internal heat transfer mechanism used in this method, and the composite materials formed by this method having a hybrid of a carbon fiber layer and a fiberglass layer.

  1. Stress distribution in antifriction composite materials

    Microsoft Academic Search

    L. V. Zabolotnyi

    1979-01-01

    The optimum shape of hard inclusions in a composite material, irrespective of the magnitude of load and mode of its application to the surface, is a spheroid or ellipsoid of revolution. The characteristic linear size of a hard inclusion should be greater than the calculated diameter of a single spot of contact. If a composite material is to exhibit high

  2. Advanced composite materials: a strong growth industry

    Microsoft Academic Search

    Lees

    1987-01-01

    Advanced composites represent a material form that will see significant growth in structural applications. The authors notes that Du Pont sees a broad opportunity for these materials and proceeds to review reasons for the company's optimism as well as their approach to this technology. Substitution of composites for metals is shown graphically since 1960 and projected to 2025. Price reductions

  3. Nanostructured multilayered thin film barriers for Mg2Si thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Battiston, S.; Boldrini, S.; Fiameni, S.; Agresti, F.; Famengo, A.; Fabrizio, M.; Barison, S.

    2012-06-01

    The Mg2Si-based alloys are promising candidates for thermoelectric energy conversion in the middle-high temperature range in order to replace lead compounds. The main advantages of silicide-based thermoelectrics are the nontoxicity and the abundance of their constituent elements in the earth crust. The drawback of such kind of materials is their oxygen sensitivity at high temperature that entails their use under vacuum or inert atmosphere. In order to limit the corrosion phenomena, nanostructured multilayered molybdenum silicide-based materials were deposited via RF magnetron sputtering onto stainless steel, alumina and silicon (100) to set up the deposition process and then onto Mg2Si pellets. XRD, EDS, FE-SEM and electrical measurements at high temperature were carried out in order to obtain, respectively, the structural, compositional, morphological and electrical characterization of the deposited coatings. At the end, the mechanical behavior of the system thin film/Mg2Si-substrate as a function of temperature and the barrier properties for oxygen protection after thermal treatment in air at high temperature were qualitatively evaluated by FE-SEM.

  4. Nanostructured multilayered thin film barriers for Mg{sub 2}Si thermoelectric materials

    SciTech Connect

    Battiston, S.; Boldrini, S.; Fiameni, S.; Agresti, F.; Famengo, A.; Fabrizio, M.; Barison, S. [CNR - IENI, Corso Stati Uniti 4, 35127 Padova (Italy)

    2012-06-26

    The Mg{sub 2}Si-based alloys are promising candidates for thermoelectric energy conversion in the middle-high temperature range in order to replace lead compounds. The main advantages of silicide-based thermoelectrics are the nontoxicity and the abundance of their constituent elements in the earth crust. The drawback of such kind of materials is their oxygen sensitivity at high temperature that entails their use under vacuum or inert atmosphere. In order to limit the corrosion phenomena, nanostructured multilayered molybdenum silicide-based materials were deposited via RF magnetron sputtering onto stainless steel, alumina and silicon (100) to set up the deposition process and then onto Mg{sub 2}Si pellets. XRD, EDS, FE-SEM and electrical measurements at high temperature were carried out in order to obtain, respectively, the structural, compositional, morphological and electrical characterization of the deposited coatings. At the end, the mechanical behavior of the system thin film/Mg{sub 2}Si-substrate as a function of temperature and the barrier properties for oxygen protection after thermal treatment in air at high temperature were qualitatively evaluated by FE-SEM.

  5. Composite Dielectric Materials for Electrical Switching

    SciTech Connect

    Modine, F.A.

    1999-04-25

    Composites that consist of a dielectric host containing a particulate conductor as a second phase are of interest for electrical switching applications. Such composites are "smart" materials that can function as either voltage or current limiters, and the difference in fimction depends largely upon whether the dielectric is filled to below or above the percolation threshold. It also is possible to combine current and voltage limiting in a single composite to make a "super-smart" material.

  6. Distribution patterns of different carbon nanostructures in silicon nitride composites.

    PubMed

    Tapasztó, Orsolya; Markó, Márton; Balázsi, Csaba

    2012-11-01

    The dispersion properties of single- and multi-walled carbon nanotubes as well as mechanically exfoliated few layer graphene flakes within the silicon nitride ceramic matrix have been investigated. Small angle neutron scattering experiments have been employed to gain information on the dispersion of the nano-scale carbon fillers throughout the entire volume of the samples. The neutron scattering data combined with scanning electron microscopy revealed strikingly different distribution patterns for different types of carbon nanostructures. The scattering intensities for single wall carbon nanotubes (SWCNTs) reveal a decay exponent characteristic to surface fractals, which indicate that the predominant part of nanotubes can be found in loose networks wrapping the grains of the polycrystalline matrix. By contrast, multi wall carbon nanotubes (MWCNTs) were found to be present mainly in the form of bulk aggregate structures, while few-layer graphene (FLG) flakes have been individually dispersed within the host matrix, under the very same preparation and processing conditions. PMID:23421284

  7. Synthesis and Electron Field-Emission of 1-D Carbon-Related Nanostructured Materials

    NASA Astrophysics Data System (ADS)

    Shih, Han C.

    2002-10-01

    Carbon nanotubes, a new stable form of carbon that was first identified in 1991 [1], are fullerene-related structures which consist of graphitic cylinders closed at either end with caps containing pentagonal rings. Although carbon nanotube structures are closely related to graphite, the curvature, symmetry and small size induce marked deviations from the graphitic behavior. Various methods have been used to produce carbon nanotubes, e.g., arc-discharge, laser-vaporization, catalytic chemical vapor deposition, but too many impurities also be produced, such as fullerenes, carbon nanoparticles and amorphous carbons. The microwave plasma enhanced chemical vapor deposition (MPECVD) system has been used to grow carbon nanotubes in this work and other 1-D carbon-related nanostructured materials was synthesized by the electron cyclotron resonance (ECR) plasma system. Plasma is generated by microwave excitation at 2.45 GHz by a magnetron passes through a waveguide and fed perpendicularly through a quartz dome into an 875 G magnetic field generated by the coils surrounding the resonance volume that creates the ECR condition. The deposition chamber was pumped down to the base pressure of 6.7X10-4 Pa (5X10-6 Torr) with a turbomolecular pump for ECR-plasma and subatmospheric pressures for MPECVD by a rotary mechanical pump. Well-aligned carbon-related nanostructures have been synthesized in nanoporous alumina or silicon with a uniform diameter of 30-100 nm by microwave excited plasma of CH_4, C_2H_2, N_2, H2 and Ar precursors. Nickel nanowires not only serve as catalysts to decompose hydrocarbons to form nanostructures but also function as an electrical conductor for other advanced applications. A negative dc bias is always applied to the substrate to promote the flow of ion fluxes through the nanochannels of the template materials that facilitate the physical adsorption and subsequent chemical absorption in the formation of carbon- and carbon-nitride nanotubes[2]. The electron field emission characteristics of the 1-D carbon-related nanostructures were measured by the conventional diode method at an ambient pressure of 1.3X10-3 Pa (10-5 Torr). The films (1X1-cm^2) were separated from the anode by ITO (indium tin oxide) coated glass, where a glass fiber spacer was maintained at 150 ?m from the cathode. The current density and electric field characteristics were measured using a Keithley 237 electrometer. A range of onset electron emission field from 3.5 to 1.5 V/?m and an emission current density up to 1 mA/cm^2 at 3V/?m have been achieved in this study, apparently superior to other carbon-based electron field emitters[3]. The results were reproducible over a period of weeks and the nanotubes did not degrade physically when exposing to a humid air of RH 90using the Fowler-Nordheim model, I=aV^2 exp (-b?_e^3/2/V) , where a and b are constants. The turn-on voltage was estimated as the voltage deviating from ln(I/V^2)-1/V curve. The effective work function (?_e=?/?) of the arrayed carbon nanotubes was calculated from the slope of the Fowler-Nordheim plot, where the value of ?, the field enhancement factor, was found to be 1517. This value increased to 3357 when nitrogen was doped, but decreased to 974 when boron was doped. The incorporation of nitrogen or boron into the carbon network apparently changes the original nanostructure and the chemical bonding. The structural and compositional modification by the incorporation of nitrogen, boron, or hydrogen into the 1-D carbon-related nanostructured materials were analyzed by FTIR , XPS , Raman spectroscopy , and FE-SEM . Various forms in connection with 1-D nanostructured materials applicable to the NEMS , e.g. , nanowelding of nanotubes[4], tubes on tube , open-end nanotubes and coils of nanofiber and nanotubes have been produced in this research depending on the plasma chemistry, catalytic effect and the design of template. [1]. S. Iijima, Nature 354, 56 (1991). [2]. S. L. Sung, S. H. Tsai, C. H. Tseng, X. W. Liu, and H. C. Shih, Appl. Phys. Lett. 74, 197 (1999). [3]. S. H. Tsai,

  8. Dispersive transport of charge carriers in disordered nanostructured materials

    NASA Astrophysics Data System (ADS)

    Sibatov, R. T.; Uchaikin, V. V.

    2015-07-01

    Dispersive transport of charge carriers in disordered nanostructured semiconductors is described in terms of integral diffusion equations nonlocal in time. Transient photocurrent kinetics is analyzed for different situations. Relation to the fractional differential approach is demonstrated. Using this relation provides specifications in interpretation of the time-of-flight data. Joint influence of morphology and energy distribution of localized states is described in frames of the trap-limited advection-diffusion on a comb structure modeling a percolation cluster.

  9. Magnetic and magneto-transport properties in nanostructured materials

    Microsoft Academic Search

    Fengyuan Yang

    2001-01-01

    Magneto-transport, magnetic and structural properties of three nanostructured systems: (1) single-crystal bismuth films with and without antidot arrays made by electrodeposition, (2) epitaxial half-metallic CrO2 films made by chemical vapor deposition (CVD), and (3) exchange-coupled Co\\/FeMn\\/permalloy trilayers prepared by magnetron sputtering are presented. Single-crystal Bi thin films have been made by electrodeposition followed by suitable annealing. X-ray diffraction verifies that

  10. High-resolution analytical TEM of nanostructured materials.

    PubMed

    Schneider, R

    2002-10-01

    This paper briefly reviews the potential applicability of analytical transmission electron microscopy (TEM) to elucidate both structural and chemical peculiarities of materials at high lateral resolution. Examples of analytical TEM investigations performed by energy-dispersive X-ray spectroscopy (EDXS), electron energy loss spectroscopy (EELS), and energy-filtered TEM (EFTEM) are presented for different materials systems including metals, ceramics, and compound semiconductors. In particular, results are given of imaging the element distribution in the interface region between gamma matrix and gamma' precipitate in the nickel-based superalloy SC16 by energy-filtered TEM. For core-shell structured BaTiO(3) particles the chemical composition and even the chemical bonding were revealed by EELS at a resolution of about 1 nm. A sub-nanometer resolution is demonstrated by energy-selective images of the Ga distribution in the surrounding of (In,Ga)As quantum dots. Moreover, the element distribution in (Al,Ga)As/AlAs multilayers with linear concentration gradients in a range of about 10 nm was investigated by EDXS line-profile analyses and EFTEM. PMID:12397484

  11. Nanostructured TiOx as a catalyst support material for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Phillips, Richard S.

    Recent interest in the development of new catalyst support materials for proton exchange membrane fuel cells (PEMFCs) has stimulated research into the viability of TiO2-based support structures. Specifically, substoichiometric TiO2 (TiOx) has been reported to exhibit a combination of high conductivity, stability, and corrosion resistance. These properties make TiOx-based support materials a promising prospect when considering the inferior corrosion resistance of traditional carbon-based supports. This document presents an investigation into the formation of conductive and stable TiOx thin films employing atomic layer deposition (ALD) and a post deposition oxygen reducing anneal (PDORA). Techniques for manufacturing TiOx-based catalyst support nanostructures by means of ALD in conjunction with carbon black (CB), anodic aluminum oxide (AAO) and silicon nanowires (SiNWs) will also be presented. The composition and thickness of resulting TiOx thin films was determined with the aid of Auger electron spectroscopy (AES), Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM). Film crystal structure was determined with X-ray diffraction (XRD) analysis. Film conductivity was calculated using four-point probe (4-PP) and film thickness measurement data. Resulting thin films show a significant decrease of oxygen in ALD TiOx films corresponding with a great increase in conductivity following the PDORA. The effectiveness of the PDORA was also found to be highly dependent on ALD process parameters. TiOx-based nanostructures were coated with platinum using one of three Pt deposition techniques. First, liquid phase deposition (LPD), which was performed at room temperature, provided equal access to catalyst support material surfaces which were suspended in solution. Second, plasma enhanced atomic layer deposition (PEALD), which was performed at 450°C, provided good Pt particle dispersion and particle size controllability. Third, physical vapor deposition (PVD), which was also performed at room temperature, was used as a low temperature vapor-phase deposition technique for comparison with PEALD Pt coated materials. The temperature of the Pt deposition technique is an important parameter to consider due to the potential adverse effects of the strong metal support interaction (SMSI) which may take place at temperatures above 200°C. Platinum coated nanostructures were analyzed electrochemically using cyclic voltammetry (CV), rotating disk electrode (RDE) and accelerated stress tests (ASTs). CV and RDE results generally show that platinum activity values are initially not as high as those typically observed for platinum on carbon; however, AST results indicate that TiO x-based materials are much more stable long-term and hence their level of activity is likely to overtake traditional platinum on carbon materials in a PEMFC system.

  12. New textile composite materials development, production, application

    NASA Technical Reports Server (NTRS)

    Mikhailov, Petr Y.

    1993-01-01

    New textile composite materials development, production, and application are discussed. Topics covered include: super-high-strength, super-high-modulus fibers, filaments, and materials manufactured on their basis; heat-resistant and nonflammable fibers, filaments, and textile fabrics; fibers and textile fabrics based on fluorocarbon poylmers; antifriction textile fabrics based on polyfen filaments; development of new types of textile combines and composite materials; and carbon filament-based fabrics.

  13. Novel high volumetric energy density nanostructured electrode materials for biomedical applications

    NASA Astrophysics Data System (ADS)

    Tong, Wei

    A definitive focus is being made to develop cathode materials of higher energy and good power for primary and rechargeable lithium batteries upon the development of implantable biomedical devices (cardiac defibrillators). In this thesis, novel electroactive nanostructured silver metal oxyfluoride perovskites, Ag1+3Mo6+(O3F 3) and Ag1+3Nb5+(O2F 4) have been successfully synthesized by a mechanochemical reaction. The formation of these perovskites was investigated throughout the Ag-Mo / Nb composition range with the use of either Ag1+ or Ag 2+ in the form of AgF and AgF2 as the reactant, respectively. The compositional study combined with XRD and extensive Raman investigation was utilized to determine structure and cation distribution and infer oxidation state. An electrochemical characterization of these silver metal oxyfluoride perovskite positive electrodes for Li batteries was investigated for the first time as a function of synthesis condition, stoichiometry and effect of Mo and Ag derived second phases. A detailed in-situ electrochemical study by XAS, Raman and XRD was performed, revealing a 3 electron silver displacement or conversion reaction at > 3 V and a 2 electron reduction of Mo6+ to Mo4+ in the region < 3 V. To further improve the rate capability of silver metal oxyfluorides, metallic Ag2F phase has been successfully synthesized through the mechanochemical reaction of Ag and AgF. Its unique metallic character within Ag layers lead to a very good electronic conductivity (7.89x10 -2 S/cm). The efficacy of SMOF composites consisting of conducting matrix (carbon black, Ag2F and Ag phase) for lithium battery was investigated through discharge rate studies. Results indicated that Ag 2F phase could be utilized as an alternative conductive additive with exceptional density.

  14. Thermal Characterization of Nanostructures and Advanced Engineered Materials

    E-print Network

    Goyal, Vivek Kumar

    2011-01-01

    promising candidates for high- efficiency thermoelectric materials.promising candidates for high-efficiency thermoelectric materials,promising candidates for high-efficiency thermoelectric materials [

  15. Advanced thermopower wave in novel ZnO nanostructures/fuel composite.

    PubMed

    Lee, Kang Yeol; Hwang, Hayoung; Choi, Wonjoon

    2014-09-10

    Thermopower wave is a new concept of energy conversion from chemical to thermal to electrical energy, produced from the chemical reaction in well-designed hybrid structures between nanomaterials and combustible fuels. The enhancement and optimization of energy generation is essential to make it useful for future applications. In this study, we demonstrate that simple solution-based synthesized zinc oxide (ZnO) nanostructures, such as nanorods and nanoparticles are capable of generating high output voltage from thermopower waves. In particular, an astonishing improvement in the output voltage (up to 3 V; average 2.3 V) was achieved in a ZnO nanorods-based composite film with a solid fuel (collodion, 5% nitrocellulose), which generated an exothermic chemical reaction. Detailed analyses of thermopower waves in ZnO nanorods- and cube-like nanoparticles-based hybrid composites have been reported in which nanostructures, output voltage profile, wave propagation velocities, and surface temperature have been characterized. The average combustion velocities for a ZnO nanorods/fuel and a ZnO cube-like nanoparticles/fuel composites were 40.3 and 30.0 mm/s, while the average output voltages for these composites were 2.3 and 1.73 V. The high output voltage was attributed to the amplified temperature in intermixed composite of ZnO nanostructures and fuel due to the confined diffusive heat transfer in nanostructures. Moreover, the extended interfacial areas between ZnO nanorods and fuel induced large amplification in the dynamic change of the chemical potential, and it resulted in the enhanced output voltage. The differences of reaction velocity and the output voltage between ZnO nanorods- and ZnO cube-like nanoparticles-based composites were attributed to variations in electron mobility and grain boundary, as well as thermal conductivities of ZnO nanorods and particles. Understanding this astonishing increase and the variation of the output voltage and reaction velocity, precise ZnO nanostructures, will help in formulating specific strategies for obtaining enhanced energy generation from thermopower waves. PMID:25133980

  16. Flame-retardant composite materials

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.

    1991-01-01

    The properties of eight different graphite composite panels fabricated using four different resin matrices and two types of graphite reinforcement are described. The resin matrices included: VPSP/BMI, a blend of vinylpolystyryl pyridine and bismaleimide; BMI, a bismaleimide; and phenolic and PSP, a polystyryl pyridine. The graphite fiber used was AS-4 in the form of either tape or fabric. The properties of these composites were compared with epoxy composites. It was determined that VPSP/BMI with the graphite tape was the optimum design giving the lowest heat release rate.

  17. Machining of Sitall-base composite materials

    Microsoft Academic Search

    L. F. Kolesnichenko; N. D. Nazarenko; A. I. Yuga; N. I. Vlasko; F. D. Ivashov; L. L. Sukhikh; G. A. Sedlyar

    1976-01-01

    Investigations have shown that in the grinding of Sitall with an abrasive tool removal of material is slow owing to poor heat transfer from the cutting zone and the high hardness of Sitall. By contrast, use of diamond disks in the grinding of Sitall-base composite materials enables high rates of material removal to be attained with a good surface finish.

  18. Materials research at Stanford University. [composite materials, crystal structure, acoustics

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Research activity related to the science of materials is described. The following areas are included: elastic and thermal properties of composite materials, acoustic waves and devices, amorphous materials, crystal structure, synthesis of metal-metal bonds, interactions of solids with solutions, electrochemistry, fatigue damage, superconductivity and molecular physics and phase transition kinetics.

  19. Oxygen Compatibility Testing of Composite Materials

    NASA Technical Reports Server (NTRS)

    Engel, Carl D.; Watkins, Casey N.

    2006-01-01

    Composite materials offer significant weight-saving potential for aerospace applications in propellant and oxidizer tanks. This application for oxygen tanks presents the challenge of being oxygen compatible in addition to complying with the other required material characteristics. This effort reports on the testing procedures and data obtained in examining and selecting potential composite materials for oxygen tank usage. Impact testing of composites has shown that most of these materials initiate a combustion event when impacted at 72 ft-lbf in the presence of liquid oxygen, though testing has also shown substantial variability in reaction sensitivities to impact. Data for screening of 14 potential composites using the Bruceton method is given herein and shows that the 50-percent reaction frequencies range from 17 to 67 ft-lbf. The pressure and temperature rises for several composite materials were recorded to compare the energy releases as functions of the combustion reactions with their respective reaction probabilities. The test data presented are primarily for a test pressure of 300 psia in liquid oxygen. The impact screening process is compared with oxygen index and autogenous ignition test data for both the composite and the basic resin. The usefulness of these supplemental tests in helping select the most oxygen compatible materials is explored. The propensity for mechanical impact ignition of the composite compared with the resin alone is also examined. Since an ignition-free composite material at the peak impact energy of 72 ft-lbf has not been identified, composite reactivity must be characterized over the impact energy level and operating pressure ranges to provide data for hazard analyses in selecting the best potential material for liquid tank usage.

  20. Nanostructured ceria-based materials: synthesis, properties, and applications Chunwen Sun,*ab

    E-print Network

    The controllable synthesis of nanostructured CeO2-based materials is an imperative issue for environment related to the CeO2-based nanomaterials, with a focus on the synthesis from one dimensional to mesoporous cerium(III) and cerium(IV). With a high abundance, cerium oxide (CeO2) is a technologically important

  1. Chemically modified and nanostructured porous silicon as a drug delivery material and device

    Microsoft Academic Search

    Emily Jessica Anglin

    2007-01-01

    This thesis describes the fabrication, chemical modification, drug release, and toxicity studies of nanostructured porous silicon for the purposes of developing a smart drug delivery device. The first chapter is an introductory chapter, presenting the chemical and physical properties of porous silicon, the concepts and issues of current drug delivery devices and materials, and how porous silicon can address the

  2. Post-doc position : Nanostructured materials for the realization of enhanced micro-supercapacitors

    E-print Network

    Ingrand, François

    Post-doc position : Nanostructured materials for the realization of enhanced micro-supercapacitors and temperature range. The integration of low-profile, miniaturized supercapacitors could, CDC, CNT, RuO2...) for the development of micro-supercapacitors. An attractive

  3. Synthesis and microwave absorption properties of graphene/nickel composite materials

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoxia; Yu, Mingxun; Zhang, Wei; Zhang, Baoqin; Dong, Lifeng

    2015-03-01

    Graphene/nickel composite materials were successfully prepared via a one-step in situ reduction from nickel chloride, graphene oxide, and hydrazine at 80 °C for 3 h. Face-centered cubic Ni nanostructures with uniform size and high dispersion assembled on graphene sheets. Through the measurement of complex relative permittivity and permeability, their microwave absorption properties were evaluated. In comparison with pure Ni nanoparticles and graphene, the composite materials demonstrated much better characteristics of microwave absorption. The lowest reflection loss value of the composites with a thickness of 3 mm can reach -23.3 dB at 7.5 GHz. Our research reveals that graphene/Ni composites are promising microwave absorption materials with desirable absorption properties and reduced material weight.

  4. Nanostructured inorganic materials: Synthesis and associated electrochemical properties

    NASA Astrophysics Data System (ADS)

    Yau, Shali Zhu

    Synthetic strategy for preparing potential battery materials at low temperature was developed. Magnetite (Fe3O4), silver hollandnite (AgxMn8O16), magnesium manganese oxide (MgxMnO 2?yH2O), and silver vanadium phosphorous oxide (Ag 2VO2PO4) were studied. Magnetite (Fe3O4) was prepared by coprecipitation induced by triethylamine from aqueous iron(II) and iron(III) chloride solutions of varying concentrations. Variation of the iron(II) and iron(III) concentrations results in crystallite size control of the Fe3O4 products. Materials characterization of the Fe3O4 samples is reported, including Brunauer-Emmitt-Teller (BET) surface area, x-ray powder diffraction (XRD), transmission electron microscopy (TEM), particle size, and saturation magnetization results. A strong correlation between discharge capacity and voltage recovery behavior versus crystallite size was observed when tested as an electrode material in lithium electrochemical cells. Silver hollandite (AgxMn8O16) was successfully synthesized through a low temperature reflux reaction. The crystallite size and silver content of AgxMn8O16 by varying the reactant ratio of silver permanganate (AgMnO4) and manganese sulfate monohydrate (MnSO4?H2O). Silver hollandite was characterized by Brunauer-Emmitt-Teller (BET) surface area, inductively coupled plasma-optical emission (ICP-OES) spectrometry, helium pycnometry, simultaneous thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), and x-ray powder diffraction (XRD). The crystallite size showed a strong correlation with silver content, BET surface area, and particle sizes. The silver hollandite cathode showed good discharge capacity retention in 30 cycles of discharge-charge. There were a good relationship between crystallite size and rate capability and pulse ability. Magnesium manganese oxide (MgxMnO2?yH 2O) was made by redox reaction by mixing sodium hydroxide (NaOH), manganese sulfate monohydrate (MnSO4?HO2), and potassium persulfate (K2S2O8). The solid samples were characterized by inductively coupled plasma-optical emission (ICP-OES) spectrometry, scanning electron microscopy (SEM), simultaneous thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), and X-ray powder diffraction (XRD). The solid had a plate-like morphology. The preliminary electrochemical results showed that MgxMnO2?yH2O had a very good cycliability and the capacity retention in 20 discharge-charge cycles. When the sample was dried at 100°C after collection, the discharge capacity would increase from 80 mAh/g to 155 mAh/g in the first discharge process in cycling test. Silver vanadium phosphorous oxide (SVPO, Ag2VO2PO 4) was prepared in various reaction temperatures. It was the first time that Ag2VO2PO4 was synthesized successfully at room temperature. The solid was characterized by Brunauer-Emmitt-Teller surface area (BET), inductively coupled plasma-optical emission (ICP-OES) spectroscopy, differential scanning calorimetry (DSC), magnetic susceptibility measurement, scanning electron microscope (SEM) and x-ray powder diffraction (XRD). Ag2VO2PO4 crystallite sizes showed a strong linear correlation with reaction temperature. The BET surface area was decreased as the crystallite size increased linearly. In addition, the acicular morphology started to develop at 50°C. The impact of silver deposition loading on the silver-polypyrrole composite electrode was studied using cyclic voltammetry. The minimum Ag loading of 0.08 mg/cm2 was determined to maximize the oxygen reduction activity for the Ag/Ppy composite catalyst. In addition, the Ag/Ppy coated carbon electrode showed higher oxygen reduction activities in both air and oxygen compared to the uncoated carbon electrode.

  5. Nanostructure, composition and mechanisms of bivalve shell growth

    NASA Astrophysics Data System (ADS)

    Jacob, D. E.; Soldati, A. L.; Wirth, R.; Huth, J.; Wehrmeister, U.; Hofmeister, W.

    2008-11-01

    Freshwater and marine cultured pearls form via identical processes to the shells of bivalves and can therefore serve as models for the biomineralization of bivalve shells in general. Their nanostructure consists of membrane-coated granules (vesicles) which contain amorphous calcium carbonate (ACC) at the beginning of the biomineralization sequence, preceding the crystallization of aragonite and vaterite. In contrast to the commonly accepted view, crystallization of ACC occurs rapidly and within the granular nano-compartments mediated by organic molecules much earlier than platelet formation. The interlamellar organic sheets in nacre that form the platelet structure of nacre themselves form by self-organization after the crystallization process of CaCO 3 is completed and, thus, cannot serve as a nucleation template for aragonite. Pores in the organic sheets are postulated to be a result of this process rather than to represent the pathways for CaCO 3 through pre-existing interlamellar sheets. The amorphous phase has the highest concentrations of Mg (5.8 mol%), Mn (6.6 mol%), S (4.7 mol%) and P (1 mol%) of the three CaCO 3-polymorphs. Mg/Ca and Mn/Ca ratios are found to decrease in the order ACC > vaterite > aragonite, corresponding to decreasing organic content in the different phases. This, as well as an observed enrichment of Mg in the organic-rich growth-banding of the pearls, suggests an at least partially organic speciation of Mg and Mn in bivalves and may be responsible for the observed physiological influence on Mg/Ca and Mn/Ca ratios in bivalves as a proxy for environmental parameters.

  6. Thermoelectric study of INSB secondary phase based nano composite materials

    NASA Astrophysics Data System (ADS)

    Zhu, Song

    In the past several decades there has been an intensive study in the field of thermoelectric study that is basically materials driven. As the simplest technology applicable in direct heat-electricity energy conversion, thermoelectricity utilizes the Seebeck effect to generate electricity from heat or conversely achieve the solid-state cooling via the Peltier effect. With many technical merits, thermoelectric devices can be used as spot-size generators or distributed refrigerators, however, their applications are restricted by the energy conversion efficiency, which is mainly determined by the figure of merit ZT of the thermoelectric materials that these devices are made of. A higher ZT (ZT=alpha2*sigma/kappa) entails a larger Seebeck coefficient (alpha), a higher electrical conductivity (sigma) and a lower thermal conductivity (kappa). However, it is challenging to simultaneously optimize these three material parameters because they are adversely correlated. To this end, a promising approach to answer this challenge is nano-compositing or microstructuring at multiple length scales. The numerous grain boundaries in nano-composite allow for significant reduction of lattice thermal conductivity via strong phonon scattering and as well an enhanced Seebeck coefficient via, carrier energy filtering effect. As the same grain boundaries also scatter carriers, a coherent interface between grains is needed to minimize the degradation of carrier mobilities. To this end,in-situ, instead of ex-situ, formation of nano-composite is preferred. It is noteworthy that electrical conductivity can be further enhanced by the injection of high-mobility carriers introduced by the secondary nano-phase. In view of the prevalent use of Antimony (Sb) in thermoelectric materials, Indium Antimonide (InSb) naturally becomes one of the most promising nano-inclusions since it possesses one of the largest carrier mobilities (˜7.8 m 2/V-s) in any semiconductors, while at the same time possesses a reasonably narrow band gap (˜0.17 eV at 300 K). In this dissertation, I experimentally investigate whether InSb could be a "good" nano-secondary phase in two thermoelectric bulk matrix materials, FeSb2 and half-Heusler compounds. In these in situ formed nano-composites, three mechanisms are utilized to decouple the otherwise adversely correlated Seebeck coefficient (alpha), electrical conductivity (sigma), and thermal conductivity (kappa). First, low energy carriers will be filtered out via the carrier energy filtering effect, enhancing the Seebeck coefficient without degrading the power factor (PF= alpha 2sigma). Second, high mobility carriers from the InSb nano-inclusions will be injected to the system to increase the electrical conductivity. Last, the numerous grain boundaries present in nano-composites allow for strong phonon scattering so as to reduce the thermal conductivity. After the initial in situ synthesis of nano-composites with the optimized composition, further nano-structuring processes are applied in the samples of FeSb2 with 0.5% atomic ratio of InSb. The results indicate that not all nano-structures are thermoelectrically favorable, multi-scale microstructures with the length scale comparable with the phonon mean free path are needed to effectively scatter phonons over a wide range of wavelength. In summary, the successful combination of the carrier energy filtering effect, high mobility carrier injection effect, and strong phonon scattering effect in the in situ synthesized FeSb2-InSb and half-Heusler-InSb nano-composites leads to a significantly enhanced ZT. This approach of in situ formation of nano-composites based on InSb secondary nano-phase may also be applied to other thermoelectric materials.

  7. In situ nanostructure generation and evolution within a bulk thermoelectric material to reduce lattice thermal conductivity.

    PubMed

    Girard, Steven N; He, Jiaqing; Li, Changpeng; Moses, Steven; Wang, Guoyu; Uher, Ctirad; Dravid, Vinayak P; Kanatzidis, Mercouri G

    2010-08-11

    We show experimentally the direct reduction in lattice thermal conductivity as a result of in situ nanostructure generation within a thermoelectric material. Solid solution alloys of the high-performance thermoelectric PbTe-PbS 8% can be synthesized through rapid cooling and subsequent high-temperature activation that induces a spontaneous nucleation and growth of PbS nanocrystals. The emergence of coherent PbS nanostructures reduces the lattice thermal conductivity from approximately 1 to approximately 0.4 W/mK between 400 and 500 K. PMID:20698594

  8. In situ nanostructure generation and evolution within a bulk thermoelectric material to reduce lattice thermal conductivity.

    SciTech Connect

    Girard, S. N.; He, J.; Li, C.; Moses, S.; Wang, G.; Uher, C.; Dravid, V. P.; Kanatzidis, M. G. (Materials Science Division); (Northwestern Univ.); (Univ. of Michigan)

    2010-07-26

    We show experimentally the direct reduction in lattice thermal conductivity as a result of in situ nanostructure generation within a thermoelectric material. Solid solution alloys of the high-performance thermoelectric PbTe-PbS 8% can be synthesized through rapid cooling and subsequent high-temperature activation that induces a spontaneous nucleation and growth of PbS nanocrystals. The emergence of coherent PbS nanostructures reduces the lattice thermal conductivity from {approx}1 to {approx}0.4 W/mK between 400 and 500 K.

  9. Controlled fabrication of sub-15nm nanostructures of an arbitrary conductive material

    NASA Astrophysics Data System (ADS)

    Hughes, Hannah; Morgan-Wall, Tyler; Hartman, Nikolaus; Markovic, Nina

    2015-03-01

    Traditional lithographic techniques that are used to produce low-dimensional nanostructures are often limited in both the minimum achievable size and the control over the final resistance of the device. To achieve such control, we had developed a wet etching method with in-situ monitoring of resistance, but this method relies on an oxide layer to electrically isolate the monitoring circuit from the etching solution. We will present a more general method for fabricating sub-15 nm nanostructures out of various conductive materials without a need for an oxide layer. This work was supported by NSF DMR-1106167.

  10. LIQUID PHASE SINTERED METAL MATRIX COMPOSITE MATERIALS

    Microsoft Academic Search

    S. J. Yankee; G. M. Janowski; B. J. Pletka

    1990-01-01

    Iron-base and aluminum-base composite materials reinforced with various ceramic particulates have been fabricated via powder metallurgy and liquid phase sintering. The advantage of this manufacturing route is that conventional powder metallurgy processing equipment can be used to fabricate metal matrix\\/ceramic composites. Furthermore, this approach makes it possible to manufacture these composites to near-net-shape. A number of matrix\\/ceramic combinations have been

  11. NASA Thermographic Inspection of Advanced Composite Materials

    NASA Technical Reports Server (NTRS)

    Cramer, K. Elliott

    2004-01-01

    As the use of advanced composite materials continues to increase in the aerospace community, the need for a quantitative, rapid, in situ inspection technology has become a critical concern throughout the industry. In many applications it is necessary to monitor changes in these materials over an extended period of time to determine the effects of various load conditions. Additionally, the detection and characterization of defects such as delaminations, is of great concern. This paper will present the application of infrared thermography to characterize various composite materials and show the advantages of different heat source types. Finally, various analysis methodologies used for quantitative material property characterization will be discussed.

  12. Composite Materials for Wind Power Turbine Blades

    Microsoft Academic Search

    Povl Brøndsted; Hans Lilholt; Aage Lystrup

    2005-01-01

    Renewable energy resources, of which wind energy is prominent, are part of the solution to the global energy problem. Wind turbine and the rotorblade concepts are reviewed, and loadings by wind and gravity as important factors for the fatigue performance of the materials are considered. Wood and composites are discussed as candidates for rotorblades. The fibers and matrices for composites

  13. Powder Metallurgy Composite Materials Strengthened with Fibers

    Microsoft Academic Search

    Suren G. Agbalyan

    2001-01-01

    The extrusion dynamics of high-strength powder metallurgy composite materials was studied. The extrusion parameters for porous compacts of copper fibers and Cu ? Mo composites were optimized. It was shown that orientation of fibers is possible only when they are sufficiently widely dispersed in the powder matrix and also when the fiber length is much greater than its diameter l

  14. Automotive applications for advanced composite materials

    Microsoft Academic Search

    Deutsch

    1978-01-01

    A description is presented of nonaerospace applications for advanced composite materials with special emphasis on the automotive applications. The automotive industry has to satisfy exacting requirements to reduce the average fuel consumption of cars. A feasible approach to accomplish this involves the development of composites cars with a total weight of 2400 pounds and a fuel consumption of 33 miles

  15. Self-healing structural composite materials

    Microsoft Academic Search

    M. R. Kessler; N. R. Sottos; S. R. White

    2003-01-01

    A self-healing fiber-reinforced structural polymer matrix composite material is demonstrated. In the composite, a microencapsulated healing agent and a solid chemical catalyst are dispersed within the polymer matrix phase. Healing is triggered by crack propagation through the microcapsules, which then release the healing agent into the crack plane. Subsequent exposure of the healing agent to the chemical catalyst initiates polymerization

  16. Method to fabricate layered material compositions

    DOEpatents

    Fleming, James G. (Albuquerque, NM); Lin, Shawn-Yu (Albuquerque, NM)

    2002-01-01

    A new class of processes suited to the fabrication of layered material compositions is disclosed. Layered material compositions are typically three-dimensional structures which can be decomposed into a stack of structured layers. The best known examples are the photonic lattices. The present invention combines the characteristic features of photolithography and chemical-mechanical polishing to permit the direct and facile fabrication of, e.g., photonic lattices having photonic bandgaps in the 0.1-20.mu. spectral range.

  17. Acoustic emission monitoring of polymer composite materials

    NASA Technical Reports Server (NTRS)

    Bardenheier, R.

    1981-01-01

    The techniques of acoustic emission monitoring of polymer composite materials is described. It is highly sensitive, quasi-nondestructive testing method that indicates the origin and behavior of flaws in such materials when submitted to different load exposures. With the use of sophisticated signal analysis methods it is possible the distinguish between different types of failure mechanisms, such as fiber fracture delamination or fiber pull-out. Imperfections can be detected while monitoring complex composite structures by acoustic emission measurements.

  18. Composite materials with improved phyllosilicate dispersion

    DOEpatents

    Chaiko, David J.

    2004-09-14

    The present invention provides phyllosilicates edge modified with anionic surfactants, composite materials made from the edge modified phyllosilicates, and methods for making the same. In various embodiments the phyllosilicates are also surface-modified with hydrophilic lipophilic balance (HLB) modifying agents, polymeric hydrotropes, and antioxidants. The invention also provides blends of edge modified phyllosilicates and semicrystalline waxes. The composite materials are made by dispersing the edge modified phyllosilicates with polymers, particularly polyolefins and elastomers.

  19. Composite materials: composition, properties and clinical applications. A literature review.

    PubMed

    Zimmerli, Brigitte; Strub, Matthias; Jeger, Franziska; Stadler, Oliver; Lussi, Adrian

    2010-01-01

    Various composite materials are available today for direct restorative techniques. The most well-known materials are the hybrid composites. This technology, based on methacrylates and different types of filler coupled with silanes, has been continuously improved. Disadvantages such as polymerisation shrinkage, bacterial adhesion and side effects due to monomer release still remain. The aim of material development is to eliminate or at least reduce these negative factors by adapting the individual components of the material. With ormocers, the methacrylate has been partially replaced by an inorganic network. According to recent studies, the biocompatibility was not improved in all cases. The development of compomer was an attempt to combine the positive properties of glassionomers with composite technology. This has only partially succeeded, because the fluoride release is low. In an in-situ study, a caries protective effect could be shown at least in the first days following filling placement with concurrent extra-oral demineralisation. By replacing the chain-monomers in the composite matrix by ring-shaped molecules, a new approach to reduce polymerisation shrinkage was investigated. A new group of materials, the siloranes, has been developed. Siloranes are hydrophobic and need to be bonded to the dental hard tissue using a special adhesive system. Long-term clinical studies are still needed to prove the superiority of this new group of materials over modern hybrid composites. PMID:21243545

  20. Ceramic composites: Enabling aerospace materials

    NASA Technical Reports Server (NTRS)

    Levine, S. R.

    1992-01-01

    Ceramics and ceramic matrix composites (CMC) have the potential for significant impact on the performance of aerospace propulsion and power systems. In this paper, the potential benefits are discussed in broad qualitative terms and are illustrated by some specific application case studies. The key issues in need of resolution for the potential of ceramics to be realized are discussed.

  1. Graphene-based Composite Materials

    NASA Astrophysics Data System (ADS)

    Rafiee, Mohammad Ali

    We investigated the mechanical properties, such as fracture toughness (KIc), fracture energy (GIc), ultimate tensile strength (UTS), Young¡¦s modulus (E), and fatigue crack propagation rate (FCPR) of epoxy-matrix composites with different weight fractions of carbon-based fillers, including graphene platelets (GPL), graphene nanoribbons (GNR), single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT), and fullerenes (C60). Only ˜0.125 wt.% GPL was found to increase the KIc of the pure epoxy by ˜65% and the GIc by ˜115%. To get similar improvement, CNT and nanoparticle epoxy composites required one to two orders of magnitude greater weight fraction of nanofillers. Moreover, ˜0.125% wt.% GPL also decreased the fatigue crack propagation rate in the epoxy by ˜30-fold. The E value of 0.1 wt.% GPL/epoxy nanocomposite was ˜31% larger than the pure epoxy while there was only an increase of ˜3% for the SWNT composites. The UTS of the pristine epoxy was improved by ˜40% with GPLs in comparison with ˜14% enhancement for the MWNTs. The KIc of the GPL nanocomposite enhanced by ˜53% over the pristine epoxy compared to a ˜20% increase for the MWNT-reinforced composites. The results of the FCPR tests for the GPL nanocomposites showed a different trend. While the CNT nanocomposites were not effective enough to suppress the crack growth at high values of the stress intensity factor (DeltaK), the reverse behavior is observed for the GPL nanocomposites. The advantage of the GPLs over CNTs in terms of mechanical properties enhancement is due to their enormous specific surface area, enhanced adhesion at filler/epoxy interface (because of the wrinkled surfaces of GPLs), as well as the planar structure of the GPLs. We also show that unzipping of MWNTs into graphene nanoribbons (GNRs) enhances the load transfer effectiveness in epoxy nanocomposites. For instance, at ˜0.3 wt.% of fillers, the Young's modulus (E) of the epoxy nanocomposite with GNRs increased by ˜30% compared to their MWNTs counterpart. The ultimate tensile strength (UTS) for ˜0.3 wt.% GNR composites showed ˜22% enhancement compared to the MWNT composites at the same loading fraction of fillers (at ˜0.3 wt.%). Our results show that unzipping effect can be used to transform carbon nanotubes into graphene nanoribbons, which are far more effective than the baseline nanotube as a nanofiller in nanocomposites. The mechanical properties of fullerence (C60) epoxy nanocomposites at different loading fractions (wt.%) of fullerene fillers in the pristine epoxy was also studied. Fullerene (C60) fillers demonstrated good potential to improve the mechanical properties of epoxy composites. However the required C60 loading fractions were ˜1% which are still an order of magnitude higher than that for graphene platelets (˜0.1%). This again illustrates the superiority of graphene as a structural reinforcement additive for epoxy polymers at low nanofiller loadings. While the main focus of this work has been on epoxy polymers, initial results with ceramic matrix and metal (aluminum) matrix composites were also generated. These results demonstrate that GPL are highly effective in enahncing the fracture properties of silicon nitride ceramics. The fracture toughness of the baseline silicon nitride matrix increased by ˜235% (from ˜2.8 to ˜6.6 MPa.m1/2) at ˜1.5% GPL volume fraction. However the results were disappointing for aluminim matrix composites. Compared to the pure aluminum, the graphene-aluminum composites showed decreased strength and hardness. This is explained in the context of enhanced aluminum carbide formation with the graphene filler. These results indicate that Graphene Platelets (GPL) show strong potential as a nanofiller for epoxy nanocomposites and can provide a performance comparable to other forms of nanofillers at a significantly lower nanofiller loading fraction.

  2. Crustacean-derived biomimetic components and nanostructured composites.

    PubMed

    Grunenfelder, Lessa Kay; Herrera, Steven; Kisailus, David

    2014-08-27

    Over millions of years, the crustacean exoskeleton has evolved into a rigid, tough, and complex cuticle that is used for structural support, mobility, protection of vital organs, and defense against predation. The crustacean cuticle is characterized by a hierarchically arranged chitin fiber scaffold, mineralized predominately by calcium carbonate and/or calcium phosphate. The structural organization of the mineral and organic within the cuticle occurs over multiple length scales, resulting in a strong and tough biological composite. Here, the ultrastructural details observed in three species of crustacean are reviewed: the American lobster (Homarus americanus), the edible crab (Cancer pagurus), and the peacock mantis shrimp (Odontodactylus scyllarus). The Review concludes with a discussion of recent advances in the development of biomimetics with controlled organic scaffolding, mineralization, and the construction of nanoscale composites, inspired by the organization and formation of the crustacean cuticle. PMID:24833136

  3. A review of nanostructured lithium ion battery materials via low temperature synthesis.

    PubMed

    Chen, Jiajun

    2013-01-01

    Nanostructured materials afford us new opportunities to improve the current technology for synthesizing Li ion batteries. Generating nanomaterials with new properties via an inexpensive approach offers a tremendous potential for realizing high performance Li-ion batteries. In this review, I mainly summarize some of the recent progress made, and describe the patents awarded on synthesizing nanostructured cathode materials for these batteries via low temperature wet- chemistry methods. From an economical view, such syntheses, especially hydrothermal synthesis, may offer the opportunities for significantly lowering the cost of manufacturing battery materials, while conferring distinct environmental advantages. Recent advances in in-situ (real time) X-ray diffraction for studying hydrothermal synthesis have great potential for bettering the rational design of advanced lithium-electrode materials. The development of this technique also will be discussed. PMID:22747718

  4. Composite multifunctional nanostructures based on ZnO tetrapods and superparamagnetic Fe3O4 nanoparticles.

    PubMed

    Villani, M; Rimoldi, T; Calestani, D; Lazzarini, L; Chiesi, V; Casoli, F; Albertini, F; Zappettini, A

    2013-04-01

    A nanocomposite material is obtained by coupling superparamagnetic magnetite nanoparticles (Fe3O4 NP) and vapor phase grown zinc oxide nanostructures with 'tetrapod' morphology (ZnO TP). The aim is the creation of a multifunctional material which retains the attractive features of ZnO (e.g. surface reactivity, strong UV emission, piezoelectricity) together with added magnetism. Structural, morphological, optical, magnetic and functional characterization are performed. In particular, the high saturation magnetization of Fe3O4 NP (above 50 A m(2) kg(-1)), the strong UV luminescence and the enhanced photocatalytic activity of coupled nanostructures are discussed. Thus the nanocomposite turns out to be suitable for applications in energy harvesting and conversion, gas- and bio-sensing, bio-medicine and filter-free photocatalysis. PMID:23478269

  5. Composite multifunctional nanostructures based on ZnO tetrapods and superparamagnetic Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Villani, M.; Rimoldi, T.; Calestani, D.; Lazzarini, L.; Chiesi, V.; Casoli, F.; Albertini, F.; Zappettini, A.

    2013-04-01

    A nanocomposite material is obtained by coupling superparamagnetic magnetite nanoparticles (Fe3O4 NP) and vapor phase grown zinc oxide nanostructures with ‘tetrapod’ morphology (ZnO TP). The aim is the creation of a multifunctional material which retains the attractive features of ZnO (e.g. surface reactivity, strong UV emission, piezoelectricity) together with added magnetism. Structural, morphological, optical, magnetic and functional characterization are performed. In particular, the high saturation magnetization of Fe3O4 NP (above 50 A m2 kg-1), the strong UV luminescence and the enhanced photocatalytic activity of coupled nanostructures are discussed. Thus the nanocomposite turns out to be suitable for applications in energy harvesting and conversion, gas- and bio-sensing, bio-medicine and filter-free photocatalysis.

  6. Nanostructured materials for selective recognition and targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Kotrotsiou, O.; Kotti, K.; Dini, E.; Kammona, O.; Kiparissides, C.

    2005-01-01

    Selective recognition requires the introduction of a molecular memory into a polymer matrix in order to make it capable of rebinding an analyte with a very high specificity. In addition, targeted drug delivery requires drug-loaded vesicles which preferentially localize to the sites of injury and avoid uptake into uninvolved tissues. The rapid evolution of nanotechnology is aiming to fulfill the goal of selective recognition and optimal drug delivery through the development of molecularly imprinted polymeric (MIP) nanoparticles, tailor-made for a diverse range of analytes (e.g., pharmaceuticals, pesticides, amino acids, etc.) and of nanostructured targeted drug carriers (e.g., liposomes and micelles) with increased circulation lifetimes. In the present study, PLGA microparticles containing multilamellar vesicles (MLVs), and MIP nanoparticles were synthesized to be employed as drug carriers and synthetic receptors respectively.

  7. Novel applications exploiting the thermal properties of nanostructured materials.

    SciTech Connect

    Eastman, J. A.

    1998-11-20

    A new class of heat transfer fluids, termed nanofluids, has been developed by suspending nanocrystalline particles in liquids. Due to the orders-of-magnitude larger thermal conductivities of solids compared to those of liquids such as water, significantly enhanced thermal properties are obtained with nanofluids. The use of nanofluids could impact many industrial sectors, including transportation, energy supply and production, electronics, textiles, and paper production by, for example, decreasing pumping power needs or reducing heat exchanger sizes. In contrast to the enhancement in effective thermal transport rates that is obtained when nanoparticles are suspended in fluids, nanocrystalline coatings are expected to exhibit reduced thermal conductivities compared to coarse-grained coatings. Reduced thermal conductivities are predicted to arise because of a reduction in the mean free path of phonons due to presence of grain boundaries. This behavior, combined with improved mechanical properties, makes nanostructured zirconia coatings excellent candidates for future applications as thermal barriers.

  8. High-performance, nanostructure LiMnPO4/C composites synthesized via one-step solid state reaction

    NASA Astrophysics Data System (ADS)

    Zheng, Jugong; Ni, Liang; Lu, Yanwen; Qin, Cancan; Liu, Panxing; Wu, Tongfu; Tang, Yuefeng; Chen, Yanfeng

    2015-05-01

    LiMnPO4 is proposed as more promising cathode material as LiFePO4, while poor electronic conductivity and Jahn-Teller effects during charge/discharge processes hinder the electrochemical performance. To overcome these problems, one-step solid state reaction method is developed to synthesize LiMnPO4/C composites, which is with nanostructure, high crystallinity and good carbon coating. Manganese oxide sources and calcination temperature are investigated as factors for preparing high-performance LiMnPO4/C for Li-ion batteries. The results show that the LiMnPO4/C composites prepared with mixed manganese oxide deliver a superior initial capacity of 153 mAh g-1 at 0.05 C and high rate performance with discharge capacities of 123 mAh g-1 at 1 C and 103 mAh g-1 at 2 C. And the LiMnPO4/C composites synthesized at 600 °C can retain 94% of the initial capacity after 200 cycles at 1 C, revealing a stable cycling stability. Therefore, one-step solid state reaction brings to light the synthesis of high performance LiMnPO4/C cathode materials and is suitable for large scale production.

  9. Effect of aspect ratio and water contamination on the electric properties of nanostructured insulating materials

    Microsoft Academic Search

    Davide Fabiani; Gian Carlo Montanari; Luigi Testa

    2010-01-01

    Organically-modified nanofiller clays can have significantly different aspect ratios as well as accumulate a relatively large amount of water in the composite bulk due to the contribution of the filler itself and the interaction between filler and polymer matrix. This paper investigates the effect of water absorption in a nanostructured thermoplastic polymer, namely ethylene-vinyl-acetate (EVA), on electrical property modifications considering

  10. Comparison of the structural and chemical composition of two unique micro/nanostructures produced by femtosecond laser interactions on nickel

    SciTech Connect

    Zuhlke, Craig A.; Anderson, Troy P.; Alexander, Dennis R. [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)] [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)

    2013-09-16

    The structural and chemical composition of two unique microstructures formed on nickel, with nanoscale features, produced using femtosecond laser surface processing (FLSP) techniques is reported in this paper. These two surface morphologies, termed mounds and nanoparticle-covered pyramids, are part of a larger class of self-organized micro/nanostructured surfaces formed using FLSP. Cross-sections of the structures produced using focused ion beam milling techniques were analyzed with a transmission electron microscope. Both morphologies have a solid core with a layer of nanoparticles on the surface. Energy dispersive X-ray spectroscopy by scanning transmission electron microscopy studies reveal that the nanoparticles are a nickel oxide, while the core material is pure nickel.

  11. Oxygen Compatibility Testing of Composite Materials

    NASA Technical Reports Server (NTRS)

    Graf, Neil A.; Hudgins, Richard J.; McBain, Michael

    2000-01-01

    The development of polymer composite liquid oxygen LO2 tanks is a critical step in creating the next generation of launch vehicles. Future launch vehicles need to minimize the gross liftoff weight (GLOW), which is possible due to the 25%-40% reduction in weight that composite materials could provide over current aluminum technology. Although a composite LO2 tank makes these weight savings feasible, composite materials have not historically been viewed as "LO2 compatible." To be considered LO2 compatible, materials must be selected that will resist any type of detrimental, combustible reaction when exposed to usage environments. This is traditionally evaluated using a standard set of tests. However, materials that do not pass the standard tests can be shown to be safe for a particular application. This paper documents the approach and results of a joint NASA/Lockheed Martin program to select and verify LO2 compatible composite materials for liquid oxygen fuel tanks. The test approach developed included tests such as mechanical impact, particle impact, puncture, electrostatic discharge, friction, and pyrotechnic shock. These tests showed that composite liquid oxygen tanks are indeed feasible for future launch vehicles.

  12. Nonmetallic materials and composites at low temperatures

    SciTech Connect

    Hartwig, G.; Evans, D.

    1982-01-01

    This book presents articles by leading scientists who explore the cryogenic behavior of such materials as epoxies, polyethylenes, polymers, various composites, and glasses. Examines the thermal and dielectric properties of these materials, as well as their elasticity, cohesive strength, resistance to strain and fracturing, and applications. Topics include thermal properties of crystalline polymers; thermal conductivity in semicrystalline polymers; ultrasonic absorption in polymethylmethacrylate; radiation damage in thin sheet fiberglass; epoxide resins; dynamic mechanical properties of poly (methacrylates); dielectric loss due to antioxidants in polyolefins; fracture measurements on polyethylene in comparison with epoxy resins; fatigue testing of epoxide resins; lap testing of epoxide resins; thermal conductivity and thermal expansion of non-metallic composite materials; nonlinear stresses and displacements of the fibers and matrix in a radially loaded circular composite ring; the strain energy release rate of glass fiber-reinforced polyester composites; charpy impact testing of cloth reinforced epoxide resin; nonmetallic and composite materials as solid superleaks; carbon fiber reinforced expoxide resins; standardizing nonmetallic composite materials.

  13. Interfacial interaction and adhesion in composite materials

    Microsoft Academic Search

    R. Y. Yee; E. C. Martin

    1984-01-01

    The interfacial interaction of composites plays an important role in the properties of material such as structural materials, solid propellants, and explosives. To study the interfacial interaction, surface and interfacial free energies were investigated. The wettability of solids was determined by the Wilhelmy plate method using a series of reference liquids. The surface free energies of these solids were calculated

  14. Structured Piezoelectric Composites: Materials and Applications

    Microsoft Academic Search

    D. A. Van den Ende

    2012-01-01

    The piezoelectric effect, which causes a material to generate a voltage when it deforms, is very suitable for making integrated sensors, and (micro-) generators. However, conventional piezoelectric materials are either brittle ceramics or certain polymers with a low thermal stability, which limits their practical application to certain specific fields. Piezoelectric composites, which contain an active piezoelectric (ceramic) phase in a

  15. NASA Thermographic Inspection of Advanced Composite Materials

    Microsoft Academic Search

    K. Elliott Cramer

    As the use of advanced composite materials continues to increase in the aerospace community, the need for a quantitative, rapid, in situ inspection technology has become a critical concern throughout the industry. In many applications it is necessary to monitor changes in these materials over an extended period of time to determine the effects of various load conditions. Additionally, the

  16. [The application of the nanostructured bioplastic material for the plastic reconstruction of perforations in the nasal septum].

    PubMed

    Grigor'eva, M V; Akimov, A V; Bagautdinov, A A

    2014-01-01

    The objective of the present work was to estimate the effectiveness of the application of the nanostructured bioplastic material for the plastic reconstruction of perforations in the nasal septum. A total of 80 patients were recruited for the study. Half of them underwent plastic reconstruction of perforations in the nasal septum with the application of the nanostructured bioplastic material. Forty patients were treated using no biotransplants. The functional state of nasal cavity mucosa was evaluated before and after surgery. It is concluded that the nanostructured bioplastic material used in the present study ensures efficacious reconstruction of nasal septum integrity after plastic correction of septal perforations. PMID:25588475

  17. NANOSTRUCTURED CERAMICS AND COMPOSITES FOR REFRACTORY APPLICATIONS IN COAL GASIFICATION

    SciTech Connect

    Paul Brown

    2005-01-31

    A class of ceramics, capable of exhibiting low coefficients of thermal expansion and catalytic properties was investigated. Investigations were directed towards nanoengineering of NZP ceramics and NZP-based composites by chemical means by controlling their compositions and processing variables. NaZr{sub 2}(PO{sub 4}){sub 3} (NZP) was synthesized by combining water-soluble precursors leading to the precipitation of a gel that was dried, calcined, pressed into pellets, then fired at 850 C. Without chemical additives, the resulting ceramic comprised pores ranging in size from approximately 25 to 50 nm and a surface area of about 30m{sup 2}/g. Hydroxyapatite, which has a needle-like morphology, was mechanically mixed with the calcined gel to template NZP crystallization. What resulted was a coarsening of the pore structure and a decrease in surface area. When copper nitrate was added to the solution during synthesis, the resulting ceramic underwent shrinkage upon firing as well as an increase in strength. HAp and copper additions combined resulted in 40% volume shrinkage and a doubling of the tensile strength to 16MPa. A very different type of porosity was achieved when silica was partly substituted for phosphorous in the NZP structure. Na{sub 3}Zr{sub 2}(Si{sub 2}P)O{sub 12} (NASCION) was synthesized in the same manner as NZP, but the fired ceramic possessed a reticulated pore structure comprising large cavities ranging in size from 5 to 50 {micro}m. The NASCION ceramic either shrank or expanded upon firing depending on when the silica was added during synthesis. When the silica precursor (amorphous, precipitated silica) was added before the calcining step, the pressed pellets expanded during firing, whereas they shrank when the silica was added after the gel was calcined. The observed dilation increased with increasing calcining temperature and particle size, up to 26%. The contraction of the ceramic when fired increased with increasing calcining temperature and a greater surface area of the gel. Direct addition of Silica fiber was only modestly beneficial. Fiber addition combined with controlled densification resulted in the greatest improvement in strength. Ion exchange properties of NASICON were established for Cs, Pb, and Cd. It was found that the extent of ion exchange depended on ion size and that Cd could be fully exchanged into NASICON. Catalytic activity of Cu and Ag substituted compositions were determined and it was found that Ag substitution reduced the temperature at which carbon black could be oxidized. However, Ag substitution results in the formation of zircon. Ion conductivity of NASCION was determined and it was found to compare well with other ionic conductors.

  18. Nanostructured thin film-based near-infrared tunable perfect absorber using phase-change material

    NASA Astrophysics Data System (ADS)

    Kocer, Hasan

    2015-01-01

    Nanostructured thin film absorbers embedded with phase-change thermochromic material can provide a large level of absorption tunability in the near-infrared region. Vanadium dioxide was employed as the phase-change material in the designed structures. The optical absorption properties of the designed structures with respect to the geometric and material parameters were systematically investigated using finite-difference time-domain computations. Absorption level of the resonance wavelength in the near-IR region was tuned from the perfect absorption level to a low level (17%) with a high positive dynamic range of near-infrared absorption intensity tunability (83%). Due to the phase transition of vanadium dioxide, the resonance at the near-infrared region is being turned on and turned off actively and reversibly under the thermal bias, thereby rendering these nanostructures suitable for infrared camouflage, emitters, and sensors.

  19. Challenges in Applying Surface Analysis Methods to Nanoparticles and Nanostructured Materials

    SciTech Connect

    Baer, Donald R.; Engelhard, Mark H.; Gaspar, Dan J.; Matson, Dean W.; Pecher, Klaus H.; Williams, Josh R.; Wang, Chong M.

    2005-03-01

    Nanostructured materials of various types and forms are formulated in a variety of novel ways and increasingly subject to many types of chemical and physical analysis. Since nanomaterial systems contain a relatively large amount of surface or interface area, it should be natural to characterize them using tools designed to analyze surfaces and interfaces. We have found that nanoparticles and other nanostructured materials present a variety of challenges. This paper reviews environmental effects on measurements of Ce-oxide nanoparticles and nanoporous silica films and focuses on efforts to quantify the ion damage and sputter rates for the Fe-oxide nanoparticles. We have found that nanoparticles appear more readily damaged and to have sputter rates that exceed “bulk” materials. To verify such effects, we need to know many details about size, size distribution, density, and shape that are not always easily obtained.

  20. Aerosol Route Synthesis and Applications of Doped Nanostructured Materials

    Microsoft Academic Search

    Manoranjan Sahu

    2011-01-01

    Nanotechnology presents an attractive opportunity to address various challenges in air and water purification, energy, and other environment issues. Thus, the development of new nanoscale materials in low-cost scalable synthesis processes is important. Furthermore, the ability to independently manipulate the material properties as well as characterize the material at different steps along the synthesis route will aide in product optimization.

  1. Dental applications of nanostructured bioactive glass and its composites

    PubMed Central

    Polini, Alessandro; Bai, Hao; Tomsia, Antoni P.

    2013-01-01

    To improve treatments for bone or dental trauma, and for diseases such as osteoporosis, cancer, and infections, scientists who perform basic research are collaborating with clinicians to design and test new biomaterials for the regeneration of lost or injured tissue. Developed some 40 years ago, bioactive glass (BG) has recently become one of the most promising biomaterials, a consequence of discoveries that its unusual properties elicit specific biological responses inside the body. Among these important properties are the capability of BG to form strong interfaces with both hard and soft tissues, and its release of ions upon dissolution. Recent developments in nanotechnology have introduced opportunities for materials sciences to advance dental and bone therapies. For example, the applications for BG expand as it becomes possible to finely control structures and physicochemical properties of materials at the molecular level. Here we review how the properties of these materials have been enhanced by the advent of nanotechnology; and how these developments are producing promising results in hard-tissue regeneration and development of innovative BG-based drug-delivery systems. PMID:23606653

  2. Structural and magnetic characterization of nanostructured iron composites formed in the presence of citrate

    NASA Astrophysics Data System (ADS)

    Ekiert, Thomas F., Jr.

    A variety of nanostructured iron composites have been prepared via the self-assembly of nanocrystalline iron particles formed in the presence of citrate ions. Through an appropriate choice of the ratio of citrate to iron ions, the self-assembled, nanostructured iron composites can be prepared so as to possess diminished coercivity, nearly the bulk magnetization of iron, and air-stability for many months, without resorting to air-free production techniques. The self-assembled particles do not agglomerate into the chains typically produced by chemical reduction, and were prepared with widely tunable sizes (75 -- 375 nm), grain sizes (18 -- 4 nm), or crystallinity (60 -- 0.5 %). Powder compacts prepared from these particles possess coercivities as low as 40 Oe and saturation magnetizations as high as 178 emu/g at room temperature. One powder with moderately high crystallinity and saturation magnetization was selected for a detailed structural and magnetic study and was consolidated into pellets at moderate pressure. TEM measurements reveal the presence of a 3.5 nm shell on these approximately 100 nm particles with an internal grain structure of approximately five nanometers. Magnetization measurements estimate that the core of this sample is essentially pure iron. The pellets were annealed under flow of forming gas in a differential scanning calorimeter by scanning to final temperatures between 300 and 600 °C, and two shallow exotherms centered at 350 and 575 °C are observed along with a deep exotherm centered at about 485 °C. The particles show no evidence of sintering until the onset of this latter peak, at which point the x-ray diffraction (XRD) determined grain size, coercivity and remanence show sharp increases. Higher anneals produce a porous network with increased particle size, and decreased porosity and coercivity. The coercivity changes nearly linearly with the grain size until the onset of sintering, as opposed to the D6 trend observed previously for nanocrystalline materials. The effective anisotropy of these samples is fit to a surface to volume relationship that indicates the particles possess a bulk anisotropy that comparable with previously established work and a negative surface anisotropy while a the estimated exchange length is minimal when approximately equal to the XRD determined grain size in accord without invoking a second magnetic phase. Zero-field cooled/field cooled magnetization measurements for samples annealed below 480 °C show behavior consistent with a high blocking temperature and broad blocking temperature distribution, while those annealed to higher temperatures show a decrease in the field-cooled magnetization with decreasing temperature consistent with spin-glass behavior. High-field measurements reveal a gradual increase in the spin stiffness and exchange stiffness constants from approximately half the bulk value through the bulk value as the annealing temperature increases, while the spin-spin interaction distance is approximately 30 percent larger than the bulk lattice constant.

  3. Low-temperature relaxation processes in a Cu-Nb nanostructured fiber composite

    NASA Astrophysics Data System (ADS)

    Vatazhuk, E. N.; Pal-Val, P. P.; Pal-Val, L. N.; Natsik, V. D.; Tikhonovsky, M. A.; Kupriyanov, A. A.

    2009-05-01

    The elastic and dissipative properties of nanostructured superconducting fiber composites Cu-32 vol.% Nb at frequencies of the order of 70kHz are investigated in the temperature range 2-320K. The composites, prepared by the method of intensive plastic deformation, consist of a fragmented copper matrix uniformly filled with niobium fibers having diameters of 200-500nm. It is found that the acoustic properties of the composite are mainly determined by the properties of the copper matrix. Near 90K a relaxation peak of the internal friction is observed, with activational parameters close to those of the Bordoni peak in copper. Below 12K the temperature dependence of the dynamic Young's modulus is described by the thermally activated relaxation of two-level systems in a highly disordered medium. The influence of high-temperature annealing on the observed effects is investigated.

  4. Effective load transfer by a chromium carbide nanostructure in a multi-walled carbon nanotube/copper matrix composite

    NASA Astrophysics Data System (ADS)

    Cho, Seungchan; Kikuchi, Keiko; Kawasaki, Akira; Kwon, Hansang; Kim, Yangdo

    2012-08-01

    Multi-walled carbon nanotube (MWCNT) reinforced copper (Cu) matrix composites, which exhibit chromium (Cr) carbide nanostructures at the MWCNT/Cu interface, were prepared through a carbide formation using CuCr alloy powder. The fully densified and oriented MWCNTs dispersed throughout the composites were prepared using spark plasma sintering (SPS) followed by hot extrusion. The tensile strengths of the MWCNT/CuCr composites increased with increasing MWCNTs content, while the tensile strength of MWCNT/Cu composite decreased from that of monolithic Cu. The enhanced tensile strength of the MWCNT/CuCr composites is a result of possible load-transfer mechanisms of the interfacial Cr carbide nanostructures. The multi-wall failure of MWCNTs observed in the fracture surface of the MWCNT/CuCr composites indicates an improvement in the load-bearing capacity of the MWCNTs. This result shows that the Cr carbide nanostructures effectively transferred the tensile load to the MWCNTs during fracture through carbide nanostructure formation in the MWCNT/Cu composite.

  5. Nanostructure and Composition of Tribo-Boundary Films Formed in Ionic Liquid Lubrication

    SciTech Connect

    Qu, Jun [ORNL; Chi, Miaofang [ORNL; Meyer III, Harry M [ORNL; Blau, Peter Julian [ORNL; Dai, Sheng [ORNL; Luo, Huimin [ORNL

    2011-01-01

    Since the idea of using ionic liquids (ILs) as lubricants was raised in 2001, many studies have been conducted in this area and results have demonstrated superior lubricating performance for a variety of ionic liquids. It is widely believed that tribochemical reactions occur between the metal surface and the IL during the wear process to form a protective tribo-boundary film on the contact area that reduces friction and wear. However, the study of this critical boundary film has been limited to top surface two-dimensional topography examination and chemical analysis in the literature. A more comprehensive characterization is needed to help understand the film formation process and the lubricating mechanism. This study demonstrated a multi-technique three-dimensional approach to characterize the IL-formed boundary films, including top surface morphology examination, cross section nanostructure characterization, and layered chemical analysis. Characterization was carried out on both ferrous and aluminum surfaces lubricated by an ammonium IL. The focused-ion-beam (FIB) technique enabled TEM/EDS examination on the cross section of the boundary film to provide direct measurement of the film thickness, visualization of the nanostructure, and analysis of composition. In addition, composition-depth profiles were generated using XPS aided by ion-sputtering to reveal the composition change at different levels of the boundary film to investigate the film formation process.

  6. Method of producing catalytic materials for fabricating nanostructures

    DOEpatents

    Seals, Roland D; Menchhofer, Paul A; Howe, Jane Y; Wang, Wei

    2013-02-19

    Methods of fabricating nano-catalysts are described. In some embodiments the nano-catalyst is formed from a powder-based substrate material and is some embodiments the nano-catalyst is formed from a solid-based substrate material. In some embodiments the substrate material may include metal, ceramic, or silicon or another metalloid. The nano-catalysts typically have metal nanoparticles disposed adjacent the surface of the substrate material. The methods typically include functionalizing the surface of the substrate material with a chelating agent, such as a chemical having dissociated carboxyl functional groups (--COO), that provides an enhanced affinity for metal ions. The functionalized substrate surface may then be exposed to a chemical solution that contains metal ions. The metal ions are then bound to the substrate material and may then be reduced, such as by a stream of gas that includes hydrogen, to form metal nanoparticles adjacent the surface of the substrate.

  7. Impact testing of textile composite materials

    NASA Technical Reports Server (NTRS)

    Portanova, Marc

    1995-01-01

    The objectives of this report were to evaluate the impact damage resistance and damage tolerance of a variety of textile composite materials. Static indentation and impact tests were performed on the stitched and unstitched uniweave composites constructed from AS4/3501-6 Carbon/Epoxy with a fiberglass yarn woven in to hold the fibers together while being stitched. Compression and tension were measured after the tests to determine the damage resistance, residual strength and the damage tolerance of the specimens.

  8. Magnetic and magneto-transport properties in nanostructured materials

    NASA Astrophysics Data System (ADS)

    Yang, Fengyuan

    2001-08-01

    Magneto-transport, magnetic and structural properties of three nanostructured systems: (1) single-crystal bismuth films with and without antidot arrays made by electrodeposition, (2) epitaxial half-metallic CrO2 films made by chemical vapor deposition (CVD), and (3) exchange-coupled Co/FeMn/permalloy trilayers prepared by magnetron sputtering are presented. Single-crystal Bi thin films have been made by electrodeposition followed by suitable annealing. X-ray diffraction verifies that the films are trigonal axis oriented single-crystal films. High resolution transmission electron microscope reveals the expected six-fold symmetry of the atomic structure of Bi(001) films. These films exhibit very large magnetoresistance (MR) at both low temperature and room temperature, as well as strong anisotropy among the perpendicular, transverse, and longitudinal geometries. At very low temperature, the MR of Bi films shows Shubnikov-de Haas oscillations, further confirming the high quality of the films. Bi films with ordered antidot arrays patterned by optical lithography exhibit pronounced angular dependence in magnetoresistance, in agreement with theoretical calculations. X-ray diffraction studies of epitaxial CrO2 films, made by CVD on TiO2(100) substrates demonstrate single-crystal quality of the films. These films exhibit a strong uniaxial magnetocrystalline anisotropy with a unique switching behavior, which can be described by a simple model. Critical behavior of the CrO2 films, determined by magnetometry with the magnetic field along the uniaxial anisotropy axis, indicates that CrO2 is a Heisenberg ferromagnet with long-range interaction. Trilayers of permalloy/FeMn/Co with various thicknesses t AF of the antiferromagnetic FeMn layer prepared by magnetron sputtering have been designed to reveal the spin structure within FeMn. A spiraling spin structure has been observed in such trilayers.

  9. Nanostructured multiferroic materials for optoelectronics and energy-related nanodevices

    Microsoft Academic Search

    Riad Nechache; Enrico Traversa; Silvia Licoccia; Federico Rosei

    2011-01-01

    Combining properties into multifunctional materials is one of innovative ways explored by the modern technology to achieve high miniaturization of integrated devices. In this context, besides their exciting physics, multiferroic materials hich combine two or more ferroic order offer opportunities for potential applications in emerging fields of spintronics, optoelectronics and data storage. For such applications, successful integration of these multifunctional

  10. Group Members Synthesis of Nanostructured Materials Advanced Characterization Techniques

    E-print Network

    modulation of diameter and composition along individual III-V nitride nanowires", Nano Letters 13, 331 for modulating nanowire diameter via particle-mediated growth", Nano Letters 13, 226-232 (2013). 3. H. Park, S) core-shell structures, imaged with scanning transmission electron microscopy (STEM). Axial

  11. Computational modeling of composite material fires.

    SciTech Connect

    Brown, Alexander L.; Erickson, Kenneth L.; Hubbard, Joshua Allen; Dodd, Amanda B.

    2010-10-01

    Composite materials behave differently from conventional fuel sources and have the potential to smolder and burn for extended time periods. As the amount of composite materials on modern aircraft continues to increase, understanding the response of composites in fire environments becomes increasingly important. An effort is ongoing to enhance the capability to simulate composite material response in fires including the decomposition of the composite and the interaction with a fire. To adequately model composite material in a fire, two physical model development tasks are necessary; first, the decomposition model for the composite material and second, the interaction with a fire. A porous media approach for the decomposition model including a time dependent formulation with the effects of heat, mass, species, and momentum transfer of the porous solid and gas phase is being implemented in an engineering code, ARIA. ARIA is a Sandia National Laboratories multiphysics code including a range of capabilities such as incompressible Navier-Stokes equations, energy transport equations, species transport equations, non-Newtonian fluid rheology, linear elastic solid mechanics, and electro-statics. To simulate the fire, FUEGO, also a Sandia National Laboratories code, is coupled to ARIA. FUEGO represents the turbulent, buoyantly driven incompressible flow, heat transfer, mass transfer, and combustion. FUEGO and ARIA are uniquely able to solve this problem because they were designed using a common architecture (SIERRA) that enhances multiphysics coupling and both codes are capable of massively parallel calculations, enhancing performance. The decomposition reaction model is developed from small scale experimental data including thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) in both nitrogen and air for a range of heating rates and from available data in the literature. The response of the composite material subject to a radiant heat flux boundary condition is examined to study the propagation of decomposition fronts of the epoxy and carbon fiber and their dependence on the ambient conditions such as oxygen concentration, surface flow velocity, and radiant heat flux. In addition to the computational effort, small scaled experimental efforts to attain adequate data used to validate model predictions is ongoing. The goal of this paper is to demonstrate the progress of the capability for a typical composite material and emphasize the path forward.

  12. School of Mechanical and Materials Engineering Composites Materials and Engineering Center

    E-print Network

    Collins, Gary S.

    program, classroom teaching in the area of mechanical or materials engineering, and serviceSchool of Mechanical and Materials Engineering and Composites Materials and Engineering Center and Materials Engineering (MME) in collaboration with the Composites Materials and Engineering Center (CMEC

  13. Preparation of Nanostructured Materials and Electrical Conductance in Complex Physical Systems

    NASA Astrophysics Data System (ADS)

    Cai, Weilong

    Production of materials with controlled physical characteristics presents a fundamentally new method for materials science. A new facility has been designed and built using evaporation onto a moving liquid surface. Using this technique metallic particles with diameters less than 200 A with well-characterized surfaces can be prepared. The applications of these nanostructured particles to fundamental investigations is discussed. Particular attention has been given to the investigations of electrical transport in three complex physical systems. Aqueous colloidal dispersions of alpha - Fe_2O_3 particles (average diameter 65 nm) have been prepared at different volume concentrations. The electrical conduction of these composites has been investigated as a function of particle concentration, temperature (from 77 K to 300 K), frequency (including the d.c. case) of the applied electric field, and the strength (up to 7 kOe) of the applied magnetic field. The conductivity increases with particle concentration and with temperature. The frequency dependence of conductivity obeys a power law with an index slightly less than unity and decreasing somewhat with increasing temperature. These observations are interpreted with a model of conduction by electron hopping between localized states. The composites also show an increase in conductivity with the application of a magnetic field. This conductivity enhancement is believed to result from field -induced agglomeration and particle chaining. The ferromagnetic Curie temperature (T _{c}) has been determined for Fe -Ge alloys as a function of Ge concentration (up to ~10 at.%) using electrical resistivity studies. The investigation shows that addition of Ge to Fe causes a small, gradual increase in T_{c} , reaching the maximum value of ~ 1050 K at ~1.5 at.%Ge, followed by a gradual decrease with higher Ge concentrations. This behavior is in sharp contrast with the usual theories which predict decrease of T_{c} with increasing the concentration of non-magnetic particles. At present time, there are no theories capable of explaining this phenomenon. The electrical conductivity of polypyrrole as a function of temperature has been investigated. The observed temperature dependence can be described by lnsigma ~ T^{-{1over 4} }. The experimental results are quantitatively analyzed in the framework of Mott's variable range hopping model. Although this model gives a reasonable description of the conductivity, it does not afford a complete description of the transport properties of polypyrrole.

  14. Thermal expansion properties of composite materials

    NASA Technical Reports Server (NTRS)

    Johnson, R. R.; Kural, M. H.; Mackey, G. B.

    1981-01-01

    Thermal expansion data for several composite materials, including generic epoxy resins, various graphite, boron, and glass fibers, and unidirectional and woven fabric composites in an epoxy matrix, were compiled. A discussion of the design, material, environmental, and fabrication properties affecting thermal expansion behavior is presented. Test methods and their accuracy are discussed. Analytical approaches to predict laminate coefficients of thermal expansion (CTE) based on lamination theory and micromechanics are also included. A discussion is included of methods of tuning a laminate to obtain a near-zero CTE for space applications.

  15. Structure-Property Relations in Nanostructured Materials: From Solar Cells to Gecko Adhesion

    E-print Network

    Rong, Zhuxia

    2014-05-27

    Structure-Property Relations in Nanostructured Materials: From Solar Cells to Gecko Adhesion Zhuxia Rong Supervisor: Prof. Ullrich Steiner Jesus College Department of Physics University of Cambridge This dissertation is submitted for the degree... in teaching me new experimental tech- niques or advising me through enlightening discussions; Alessandro Sepe and Kai Scherer for the productive collaboration; Pola Goldberg-Oppenheimer for her efforts on the gecko project; Stefan Guldin for the open...

  16. The optical applications of 3D sub-wavelength block-copolymer nanostructured functional materials

    E-print Network

    Poole, Zsolt; Ohodnicki, Paul; Chen, Kevin

    2015-01-01

    A method to engineer the refractive indices of functional materials (TiO2, ZnO, SnO2, SiO2), by nanostructuring in the deep sub-wavelength regime (light reflections from 38% down to ~3% with a wide angular span, are demonstrated with the developed wet processing route. A high temperature oxygen free fiber optic hydrogen sensor realized by accessing nano-engine...

  17. Wetting, superhydrophobicity, and icephobicity in biomimetic composite materials

    NASA Astrophysics Data System (ADS)

    Hejazi, Vahid

    Recent developments in nano- and bio-technology require new materials. Among these new classes of materials which have emerged in the recent years are biomimetic materials, which mimic structure and properties of materials found in living nature. There are a large number of biological objects including bacteria, animals and plants with properties of interest for engineers. Among these properties is the ability of the lotus leaf and other natural materials to repel water, which has inspired researchers to prepare similar surfaces. The Lotus effect involving roughness-induced superhydrophobicity is a way to design nonwetting, self-cleaning, omniphobic, icephobic, and antifouling surfaces. The range of actual and potential applications of superhydrophobic surfaces is diverse including optical, building and architecture, textiles, solar panels, lab-on-a-chip, microfluidic devices, and applications requiring antifouling from biological and organic contaminants. In this thesis, in chapter one, we introduce the general concepts and definitions regarding the wetting properties of the surfaces. In chapter two, we develop novel models and conduct experiments on wetting of composite materials. To design sustainable superhydrophobic metal matrix composite (MMC) surfaces, we suggest using hydrophobic reinforcement in the bulk of the material, rather than only at its surface. We experimentally study the wetting properties of graphite-reinforced Al- and Cu-based composites and conclude that the Cu-based MMCs have the potential to be used in the future for the applications where the wear-resistant superhydrophobicity is required. In chapter three, we introduce hydrophobic coating at the surface of concrete materials making them waterproof to prevent material failure, because concretes and ceramics cannot stop water from seeping through them and forming cracks. We create water-repellant concretes with CA close to 160o using superhydrophobic coating. In chapter four, experimental data are collected in terms of oleophobicity especially when underwater applications are of interest. We develop models for four-phase rough interface of underwater oleophobicity and develop a novel approach to predict the CA of organic liquid on the rough surfaces immersed in water. We investigate wetting transition on a patterned surface in underwater systems, using a phase field model. We demonstrated that roughening on an immersed solid surface can drive the transition from Wenzel to Cassie-Baxter state. This discovery improves our understanding of underwater systems and their surface interactions during the wetting phenomenon and can be applied for the development of underwater oil-repellent materials which are of interest for various applications in the water industry, and marine devices. In chapter five, we experimentally and theoretically investigate the icephobicity of composite materials. A novel comprehensive definition of icephobicity, broad enough to cover a variety of situations including low adhesion strength, delayed ice crystallization, and bouncing is determined. Wetting behavior and ice adhesion properties of various samples are theoretically and experimentally compared. We conclude superhydrophobic surfaces are not necessarily icephobic. The models are tested against the experimental data to verify the good agreement between them. The models can be used for the design of novel superhydrophobic, oleophobic, omniphobic and icephobic composite materials. Finally we conclude that creating surface micro/nanostructures using mechanical abrasion or chemical etching as well as applying low energy materials are the most simple, inexpensive, and durable techniques to create superhydrophobic, oleophobic, and icephobic materials.

  18. Frictional Ignition Testing of Composite Materials

    NASA Technical Reports Server (NTRS)

    Peralta, Steve; Rosales, Keisa; Robinson, Michael J.; Stoltzfus, Joel

    2006-01-01

    The space flight community has been investigating lightweight composite materials for use in propellant tanks for both liquid and gaseous oxygen for space flight vehicles. The use of these materials presents some risks pertaining to ignition and burning hazards in the presence of oxygen. Through hazard analysis process, some ignition mechanisms have been identified as being potentially credible. One of the ignition mechanisms was reciprocal friction; however, test data do not exist that could be used to clear or fail these types of materials as "oxygen compatible" for the reciprocal friction ignition mechanism. Therefore, testing was performed at White Sands Test Facility (WSTF) to provide data to evaluate this ignition mechanism. This paper presents the test system, approach, data results, and findings of the reciprocal friction testing performed on composite sample materials being considered for propellant tanks.

  19. Testing of NCSX Composite Coil Material Properties

    SciTech Connect

    Kozub, Thomas; Jurczynski, Stephan; Chrzanowski, James [Princeton Plasma Physics Laboratory (United States)

    2005-05-15

    The National Compact Stellarator Experiment (NCSX) is now in design and requires 18 modular coils that are constructed to a highly complex geometry. The modular coil conductors are designed as a composite of a fine gauge stranded copper cable shaped to the required geometry and vacuum impregnated with a resin. These composite conductors exhibit unique material properties that must be determined and verified through testing. The conductor material properties are necessary for design modeling and performance validation. This paper will present the methods used to test and measure the coil conductor material properties, the unique challenges in measuring these complex materials at both room and liquid nitrogen temperatures and the results of those tests.

  20. Ground exposure of composite materials for helicopters

    NASA Technical Reports Server (NTRS)

    Baker, D. J.

    1984-01-01

    Residual strength results are presented on four composite material systems that were exposed for three years at locations on the North American Continent. The exposure locations are near the areas where Bell Model 206L Helicopters, that are in a NSA/U.S. Army sponsored flight service program, are flying in daily commercial service. The composite systems are: (1) Kevlar-49 fabric/F-185 epoxy; (2) Kevlar-49 fabric/LRF-277 epoxy; (3) Kevlar-49 fabric/CE-306 epoxy; and (4) T-300 Graphite/E-788 epoxy. All material systems exhibited good strength retention in compression and short beam shear. The Kevlar-49/LRF-277 epoxy retained 88 to 93 percent of the baseline strength while the other material systems exceeded 95 percent of baseline strength. Residual tensile strength of all materials did not show a significant reduction. The available moisture absorption data is also presented.

  1. Early Fatigue Damage Detection in Composite Materials

    Microsoft Academic Search

    J. J. Nevadunsky; J. J. Lucas; M. J. Salkind

    1975-01-01

    Detection of early fatigue damage in composite materials by nondestructive inspection (NDI) techniques has been demonstrated for ±45° Glass\\/Epoxy, and ±45°\\/0° Graphite\\/Glass\\/Epoxy. Dynamic axial modulus and temperature were monitored continuously with a correlation between temperature rise and modulus decrease observed. The modulus decrease and temperature rise are indicative of irreversible damage in these materials.Torsional modulus measurements and coin tap tests

  2. High capacitive performance of nanostructured Mn-Ni-Co oxide composites for supercapacitor

    SciTech Connect

    Luo Jianmin [Institute of Applied Chemistry, Xinjiang University, Urumqi 830046 (China); Gao Bo [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Zhang Xiaogang [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)], E-mail: azhangxg@163.com

    2008-05-06

    Nanostructured Mn-Ni-Co oxide composites (MNCO) were prepared by thermal decomposition of the precursor obtained by chemical co-precipitation of Mn, Ni and Co salts. The chemical composition and morphology were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The electrochemical capacitance of MNCO electrode was examined by cyclic voltammetry, impedance and galvanostatic charge-discharge measurements. The results showed that MNCO electrode exhibited the good electrochemical characteristics. A maximum capacitance value of 1260 F g{sup -1} could be obtained within the potential range of -0.1 to 0.4 V versus saturated calomel electrode (SCE) in 6 mol L{sup -1} KOH electrolyte.

  3. Electromagnetic and Microwave Absorption Properties of Carbonyl Tetrapod-Shaped Zno Nanostructures Composite Coatings

    NASA Astrophysics Data System (ADS)

    Yu, Haibo; Qin, Hui; Huang, Yunhua

    2012-08-01

    CIP/T-ZnO/EP composite coatings with carbonyl iron powders (CIP) and tetrapodshaped ZnO (T-ZnO) nanostructures as absorbers, and epoxy resin (EP) as matrix were prepared. The complex permittivity, permeability and microwave absorption properties of the coatings were investigated in the frequency range of 2-18 GHz. The effects of the weight ratio (CIP/T-ZnO/EP), the thickness and the solidification temperature on microwave absorption properties were discussed. When the weight ratio (CIP/TZnO/ EP), the thickness and the solidification temperature is 28:2:22, 1.8 mm, and 10°C, respectively, the optimal wave absorption with the minimum reflection loss (RL) value of -22.38 dB at 15.67 GHz and the bandwidth (RL<-10 dB) of 5.74 GHz was obtained, indicating that the composite coatings may have a promising application in Ku-band (12-18 GHz).

  4. Composite materials for rail transit systems

    NASA Technical Reports Server (NTRS)

    Griffin, O. Hayden, Jr.; Guerdal, Zafer; Herakovich, Carl T.

    1987-01-01

    The potential is explored for using composite materials in urban mass transit systems. The emphasis was to identify specific advantages of composite materials in order to determine their actual and potential usage for carbody and guideway structure applications. The literature was reviewed, contacts were made with major domestic system operators, designers, and builders, and an analysis was made of potential composite application to railcar construction. Composites were found to be in use throughout the transit industry, usually in secondary or auxiliary applications such as car interior and nonstructural exterior panels. More recently, considerable activity has been initiated in the area of using composites in the load bearing elements of civil engineering structures such as highway bridges. It is believed that new and improved manufacturing refinements in pultrusion and filament winding will permit the production of beam sections which can be used in guideway structures. The inherent corrosion resistance and low maintenance characteristics of composites should result in lowered maintenance costs over a prolonged life of the structure.

  5. Processing and nanostructure influences on mechanical properties of thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Schmidt, Robert David

    Thermoelectric (TE) materials are materials that can generate an electric current from a thermal gradient, with possible service in recovery of waste heat such as engine exhaust. Significant progress has been made in improving TE conversion efficiency, typically reported according to the figure of merit, ZT, with several recent papers publishing ZT values above 2. Furthermore, cost reductions may be made by the use of lower cost elements such as Mg, Si, Sn, Pb, Se and S in TE materials, while achieving ZT values between 1.3 and 1.8. To be used in a device, the thermoelectric material must be able to withstand the applied thermal and mechanical forces without failure. However, these materials are brittle, with low fracture toughness typically less than 1.5 MPa-m1/2, and often less than 0.5 MPa-m1/2. For comparison, window glass is approximately 0.75 MPa-m1/2. They have been optimized with nanoprecipitates, nanoparticles, doping, alterations in stoichiometry, powder processing and other techniques, all of which may alter the mechanical properties. In this study, the effect of SiC nanoparticle additions in Mg2Si, SnTe and Ag nanoparticle additions in the skutterudite Ba0.3Co 4Sb12 on the elastic moduli, hardness and fracture toughness are measured. Large changes (˜20%) in the elastic moduli in SnTe 1+x as a function of x at 0 and 0.016 are shown. The effect on mechanical properties of doping and precipitates of CdS or ZnS in a PbS or PbSe matrix have been reported. Changes in sintering behavior of the skutterudite with the Ag nanoparticle additions were explored. Possible liquid phase sintering, with associated benefits in lower processing temperature, faster densification and lower cost, has been shown. A technique has been proposed for determining additional liquid phase sintering aids in other TE materials. The effects of porosity, grain size, powder processing method, and sintering method were explored with YbAl3 and Ba0.3Co4Sb 12, with the porosity dependence of the elastic moduli reported. Only one other TE material has the porosity dependence of the elastic moduli previously reported in the literature, lead-antimony-silver-tellurium (LAST), and the effect of different powder processing and sintering methods has never been reported previously on TE materials.

  6. Characterization of self-healing composite materials

    Microsoft Academic Search

    Kevin John Ford

    2006-01-01

    Damage occurs in almost every composite material in the form of microcracks that develop in the epoxy matrix that binds the fibers together. Researchers at the University of Illinois Urbana Champaign have recently developed a method to reverse the effects of, or heal, damage in the epoxy matrix. Their in-situ self-healing system uses embedded microcapsules and a catalyst that trigger

  7. Computer aided design of multifunctional composite materials

    Microsoft Academic Search

    V. V. Kafarov; I. N. Dorokhov; A. Ramirez; N. I. Kafarova

    1996-01-01

    This paper deal with a multicriterion compromise problem of production of a multifunctional material on the basis of a stochastic composite with several mutually distributed phases. A formal technique for solving this problem is proposed based on the methods of topological feedback, mathematical morphology, percolation theory, and the theory of discrete phase mappings. By way of illustration, this formal technique

  8. Plastic working of laminated composite materials

    Microsoft Academic Search

    S. V. Voronov; D. G. Devoino

    1982-01-01

    Plastic working can be successfully employed for increasing the strength of the joint in a laminated composite material whose components react with each other during high-speed cladding, with the formation of brittle intermetallic compouds. At the same time, by suitable choice of reduction and mismatch, it is possible to produce straight bimetallic strips by rolling them with mismatched peripheral roll

  9. Mechanical properties of some composite materials

    Microsoft Academic Search

    S. A. Golovin; V. S. Zuev

    1976-01-01

    It is commonly believed that steels and alloys based on heat-resistant metals have low damping properties and limited endurance. However, the development of new composite materials (based on these metals) with heterogeneous structure, consisting of a rigid matrix and soft inclusions, has made it possible to obtain alloys with special properties. Sintering and impregnation are particularly important during production of

  10. Moisture Absorption and Desorption of Composite Materials

    Microsoft Academic Search

    Chi-Hung Shen; George S. Springer

    1976-01-01

    Expressions are presented for the moisture distribution and the mois ture content as a function of time of one dimensional homogeneous and composite materials exposed either on one side or on both sides to humid air or to water. The results apply during both moisture absorption and desorption when the moisture content and the temperature of the environ ment are

  11. Composite materials in flexible multibody systems

    Microsoft Academic Search

    Maria Augusta Neto; Jorge A. C. Ambrósio; Rogério P. Leal

    2006-01-01

    In this work the flexible multibody dynamics formulations of complex models are extended to include elastic components made of laminated composite materials. The only limitation for the deformation of a structural member is that it must be elastic and linear when described in a body fixed frame. A finite element model for each flexible body is obtained such that the

  12. INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS 1 Introduction

    E-print Network

    Boyer, Edmond

    are injected by a low viscosity resin. During this process, we have to pay particular attention to the void materials can be elaborated by Liquid Composite Molding (LCM), a family of processes where fibrous preforms flow rates. Liquid is injected in the T- shaped junction by two syringe compressors in setting two

  13. Nanostructured material for advanced energy storage : magnesium battery cathode development

    Microsoft Academic Search

    Wolfgang M. Sigmund; Karran V. Woan; Nelson Simmons Bell

    2010-01-01

    Magnesium batteries are alternatives to the use of lithium ion and nickel metal hydride secondary batteries due to magnesium's abundance, safety of operation, and lower toxicity of disposal. The divalency of the magnesium ion and its chemistry poses some difficulties for its general and industrial use. This work developed a continuous and fibrous nanoscale network of the cathode material through

  14. Nanostructured materials for advanced energy conversion and storage devices

    Microsoft Academic Search

    Antonino Salvatore Aricò; Peter Bruce; Bruno Scrosati; Jean-Marie Tarascon; Walter van Schalkwijk

    2005-01-01

    New materials hold the key to fundamental advances in energy conversion and storage, both of which are vital in order to meet the challenge of global warming and the finite nature of fossil fuels. Nanomaterials in particular offer unique properties or combinations of properties as electrodes and electrolytes in a range of energy devices. This review describes some recent developments

  15. Synthesis and characterization of novel nanostructured thermoelectric materials

    Microsoft Academic Search

    Xiaofeng Qiu; Clemens Burda

    2005-01-01

    Having been hibernated for almost 50 years, research in thermoelectric materials is beginning to regain activity because of the recent advances in nanoscience and nanotechnology. Thermoelectric is an old topic, which was discovered as early as 1821 by Thomas Johann Seebeck. During the following 120 years, great advances in both the theories and experiments were achieved. Since the 1950s, studies

  16. Thermal properties of graphene and nanostructured carbon materials

    Microsoft Academic Search

    Alexander A. Balandin

    2011-01-01

    Recent years have seen a rapid growth of interest by the scientific and engineering communities in the thermal properties of materials. Heat removal has become a crucial issue for continuing progress in the electronic industry, and thermal conduction in low-dimensional structures has revealed truly intriguing features. Carbon allotropes and their derivatives occupy a unique place in terms of their ability

  17. Autophagous spacecraft composite materials for orbital propulsion

    NASA Astrophysics Data System (ADS)

    Joshi, Prakash; Upschulte, Bernard L.; Gelb, Alan H.; Green, B. David; Lester, Dean M.; Wallace, Ingvar; Starrett, W. David; Marshall, David W.

    2002-07-01

    We are developing structural polymer composite materials that can be converted into fuels and combusted with oxidizers for orbital propulsion of spacecraft. We have identified candidate materials and demonstrated sustained combustion with nitrogen tetroxide (NTO) as an oxidizer. To improve reaction chemistry we have evaluated several energetic additives. Detailed material compatibility tests were conducted to identify stable combinations of structural polymer and energetic additives. We have also demonstrated sustained combustion of structural polymeric materials with embedded additives and NTO. In the next phase of research, we plan to investigate hydrogen peroxide as the oxidizer. Samples of composites comprising thin metallic facesheets, structural polymer propellant matrix, and metallic mesh reinforcements (that also serve as electrical heaters/igniters for pyrolysis) were fabricated and their mechanical properties were measured. Concept of a spacecraft structural stringer, which also functions as a thruster, was developed using the composite material formulation. Both all solid and hybrid stringer-thruster designs have been developed. Prototype stringer-thrusters will be fabricated and tested in Phase II.

  18. Nanostructured high-energy cathode materials for advanced lithium batteries

    NASA Astrophysics Data System (ADS)

    Sun, Yang-Kook; Chen, Zonghai; Noh, Hyung-Joo; Lee, Dong-Ju; Jung, Hun-Gi; Ren, Yang; Wang, Steve; Yoon, Chong Seung; Myung, Seung-Taek; Amine, Khalil

    2012-11-01

    Nickel-rich layered lithium transition-metal oxides, LiNi1-xMxO2 (M?=?transition metal), have been under intense investigation as high-energy cathode materials for rechargeable lithium batteries because of their high specific capacity and relatively low cost. However, the commercial deployment of nickel-rich oxides has been severely hindered by their intrinsic poor thermal stability at the fully charged state and insufficient cycle life, especially at elevated temperatures. Here, we report a nickel-rich lithium transition-metal oxide with a very high capacity (215?mA?h?g-1), where the nickel concentration decreases linearly whereas the manganese concentration increases linearly from the centre to the outer layer of each particle. Using this nano-functional full-gradient approach, we are able to harness the high energy density of the nickel-rich core and the high thermal stability and long life of the manganese-rich outer layers. Moreover, the micrometre-size secondary particles of this cathode material are composed of aligned needle-like nanosize primary particles, resulting in a high rate capability. The experimental results suggest that this nano-functional full-gradient cathode material is promising for applications that require high energy, long calendar life and excellent abuse tolerance such as electric vehicles.

  19. Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion

    NASA Technical Reports Server (NTRS)

    Kang, Jinho; Marshall, I. A.; Torrico, M. N.; Taylor, C. R.; Ely, Jeffry; Henderson, Angel Z.; Kim, J.-W.; Sauti, G.; Gibbons, L. J.; Park, C.; Lowther, S. E.; Lillehei, P. T.; Bryant, R. G.

    2012-01-01

    Tailoring the solar absorptivity (alpha(sub s)) and thermal emissivity (epsilon(sub T)) of materials constitutes an innovative approach to solar energy control and energy conversion. Numerous ceramic and metallic materials are currently available for solar absorbance/thermal emittance control. However, conventional metal oxides and dielectric/metal/dielectric multi-coatings have limited utility due to residual shear stresses resulting from the different coefficient of thermal expansion of the layered materials. This research presents an alternate approach based on nanoparticle-filled polymers to afford mechanically durable solar-absorptive and thermally-emissive polymer nanocomposites. The alpha(sub s) and epsilon(sub T) were measured with various nano inclusions, such as carbon nanophase particles (CNPs), at different concentrations. Research has shown that adding only 5 wt% CNPs increased the alpha(sub s) and epsilon(sub T) by a factor of about 47 and 2, respectively, compared to the pristine polymer. The effect of solar irradiation control of the nanocomposite on solar energy conversion was studied. The solar irradiation control coatings increased the power generation of solar thermoelectric cells by more than 380% compared to that of a control power cell without solar irradiation control coatings.

  20. Nanostructured solar irradiation control materials for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Kang, Jin Ho; Marshall, Iseley A.; Torrico, Mattew N.; Taylor, Chase R.; Ely, Jeffry; Henderson, Angel; Sauti, Godfrey; Gibbons, Luke J.; Kim, Jae-Woo; Park, Cheol; Lowther, Sharon E.; Lillehei, Peter T.; Bryant, Robert G.

    2012-10-01

    Tailoring the solar absorptivity (?s) and thermal emissivity (?T) of materials constitutes an innovative approach to solar energy control and energy conversion. Numerous ceramic and metallic materials are currently available for solar absorbance/thermal emittance control. However, conventional metal oxides and dielectric/metal/dielectric multi-coatings have limited utility due to residual shear stresses resulting from the different coefficient of thermal expansion of the layered materials. This research presents an alternate approach based on nanoparticle-filled polymers to afford mechanically durable solar-absorptive and thermally-emissive polymer nanocomposites. The ?s and ?T were measured with various nano inclusions, such as carbon nanophase particles (CNPs), at different concentrations. Research has shown that adding only 5 wt% CNPs increased the ?s and ?T by a factor of about 47 and 2, respectively, compared to the pristine polymer. The effect of solar irradiation control of the nanocomposite on solar energy conversion was studied. The solar irradiation control coatings increased the power generation of solar thermoelectric cells by more than 380% compared to that of a control power cell without solar irradiation control coatings.

  1. A risk forecasting process for nanostructured materials, and nanomanufacturing

    NASA Astrophysics Data System (ADS)

    Wiesner, Mark R.; Bottero, Jean-Yves

    2011-09-01

    Nanomaterials exhibit novel properties that enable new applications ranging from molecular electronics to energy production. Proactive consideration of the potential impacts on human health and the environment resulting from nanomaterial production and use requires methods for forecasting risk associated with of these novel materials. However, the potential variety of nanomaterials is virtually infinite and a case-by-case analysis of the risks these materials may pose is not possible. The challenge of forecasting risk for a broad number of materials is further complicated by large degrees of uncertainty concerning production amounts, the characteristics and uses of these materials, exposure pathways, and a scarcity of data concerning the relationship between nanomaterial characteristics and their effects on organisms and ecosystems. A traditional risk assessment on nanomaterials is therefore not possible at this time. In its place, an evolving process is needed for analyzing the risks associated with emerging nanomaterials-related industries. In this communication, we propose that such a process should include the following six key features: (1) the ability to generate forecasts and associated levels of uncertainty for questions of immediate concern; (2) a consideration of all pertinent sources of nanomaterials; (3) an inclusive consideration of the impacts of activities stemming from nanomaterial use and production that extends beyond the boundaries of toxicology and include full life cycle impacts; (4) the ability to adapt and update risk forecasts as new information becomes available; (5) feedback to improve information gathering; and (6) feedback to improve nanomaterial design. Feature #6 implies that the potential risks of nanomaterials must ultimately be determined as a function of fundamental, quantifiable properties of nanomaterials, so that when these properties are observed in a new material, they can be recognized as indicators of risk. Thus, the required risk assessment process for nanomaterials addresses needs that span from urgent, short-term questions dealing with nanomaterials currently in commerce, to longer-term issues that will require basic research and advances in theory. In the following sections we outline issues surrounding each of these six features and discuss.

  2. ACEE Composite Structures Technology: Review of selected NASA research on composite materials and structures

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The NASA Aircraft Energy Efficiency (ACEE) Composite Primary Aircraft Structures Program was designed to develop technology for advanced composites in commercial aircraft. Research on composite materials, aircraft structures, and aircraft design is presented herein. The following parameters of composite materials were addressed: residual strength, damage tolerance, toughness, tensile strength, impact resistance, buckling, and noise transmission within composite materials structures.

  3. New Composite Thermoelectric Materials for Macro-size Applications (APS Colloquium, 2008)

    SciTech Connect

    Dresselhaus, Mildred (MIT) [MIT

    2008-09-03

    A review will be given of several important recent advances in both thermoelectrics research and industrial thermoelectric applications, which have attracted much attention, increasing incentives for developing advanced materials appropriate for large-scale applications of thermoelectric devices. One promising strategy is the development of materials with a dense packing of random nanostructures as a route for the sacle-up of thermoelectrics applications. The concepts involved in designing composite materials containing nanostructures for thermoelectric applications will be discussed in general terms. Specific application is made to the Bi{sub 2}Te{sub 3} nanocomposite system for use in power generation. Also emphasized are the scientific advantages of the nanocomposite approach for the simultaneous increase in the power factor and decrease of the thermal conductivity, along with the practical advantages of having bulk samples for property measurements and device applications. A straightforward path is identified for the scale-up of thermoelectric materials synthesis containing nanostructured constituents for use in thermoelectric applications. We end with some vision of where the field of thermoelectrics is now heading.

  4. Elementary damping properties in braided composite materials

    NASA Astrophysics Data System (ADS)

    Dion, Bernard L.; Sadler, Robert; Silverberg, Larry

    1994-05-01

    This paper investigates the damping level trends of three-dimensionally braided composites as a function of matrix material, fiber-matrix interface, fiber braid angle, fiber volume, and axial fiber tow size. With knowledge of such trends, designers may increase the structural damping in a 3-D braided composite component, thereby reducing component vibration, shock response, and fatigue. The logarithmic decrements of the fundamental mode response of cantilevered, 3-D braided composite beam specimens were calculated for comparison. Although the logarithmic decrements of two specimens, differing only in their matrix materials (Tactix 123 and Epon 828), were essentially identical, both were considerably larger than that for steel. The value for the decrement of these two composite specimens' response was taken as a reference. Altering the nature of the fiber-matrix interface by lubricating the fibers before specimen consolidation greatly increased the damping relative to the baseline. Trends of increasing damping were measured with both increasing fiber braid angle and fiber volume. Finally, increasing levels of damping are reported for decreases in axial fiber tow size. Explanations for these trends, based on the possible microscopic and macroscopic nature of the braided composites, are offered.

  5. Conversion of cellulose materials into nanostructured ceramics by biomineralization

    SciTech Connect

    Shin, Yongsoon; Exarhos, Gregory J.

    2007-06-01

    Synthesis of hierarchically ordered silica materials having ordered wood cellular structures has been demonstrated through in-situ mineralization of wood by means of surfactant-directed mineralization in solutions of different pH. At low pH, silicic acid penetrates the buried interfaces of the wood cellular structure without clogging the pores to subsequently “molecularly paint” the interfaces thereby forming a positive replica following calcinations. At high pH, the hydrolyzed silica rapidly condenses to fill the open cells and pits within the structure resulting in a negative replica of the structure. Surfactant-templated mineralization in acid solutions leads to the formation of micelles that hexagonally pack at the wood interfaces preserving structural integrity while integrating hexagonally ordered nanoporosity into the structure of the cell walls following thermal treatment in air. The carbothermal reduction of mineralized wood with silica at high temperature produces biomorphic silicon carbide (SiC) materials, which are typical aggregations of ?-SiC nanoparticles. To understand the roles of each component (lignin, crystalline cellulose, amorphous cellulose) comprising the natural biotemplates in the transformation to SiC rods, three different cellulose precursors including unbleached and bleached pulp, and cellulose nanocrystals have been utilized. Lignin in unbleached pulp blocked homogeneous penetration of silica into the pores between cellulose fibers resulting in non-uniform SiC fibers containing thick silica layers. Bleached pulp produced uniform SiC rods with camelback structures (80nm in diameter; ~50?m in length), indicating that more silica infiltrates into the amorphous constituent of cellulose to form chunky rather than straight rod structures. The cellulose nanocrystal (CNXL) material produced clean and uniform SiC nanowires (70nm in diameter; >100?m in length) without the camelback structure.

  6. Aluminum composite materials for multichip modules

    NASA Astrophysics Data System (ADS)

    Premkumar, M. K.; Hunt, W. H.; Sawtell, R. R.

    1992-07-01

    In the intensive materials development activities for electronic packaging and thermal management applications, the subclass of materials in which SiC particles reinforce aluminum alloy matrices has emerged as one with an especially attractive combination of physical properties, manufacturing flexibility, and cost. One benefit of these materials is the ability to tailor the physical properties through the selection of both reinforcement and alloy variables to match the thermal expansion coefficient of other electronic materials. In addition, the manufacturing flexibility of the various processes allows for shape complexity as well as selective reinforcement placement in the component to optimize system producibility. Finally, because raw materials are inherently inexpensive and low-cost production routes have been identified, aluminum composites may offer a range of cost-effective solutions to emerging problems in electronic packaging and thermal-management applications.

  7. Fabrication of poly(ethylene glycol): gelatin methacrylate composite nanostructures with tunable stiffness and degradation for vascular tissue engineering.

    PubMed

    Kim, Peter; Yuan, Alex; Nam, Ki-Hwan; Jiao, Alex; Kim, Deok-Ho

    2014-06-01

    Although synthetic polymers are desirable in tissue engineering applications for the reproducibility and tunability of their properties, synthetic small diameter vascular grafts lack the capability to endothelialize in vivo. Thus, synthetically fabricated biodegradable tissue scaffolds that reproduce important aspects of the extracellular environment are required to meet the urgent need for improved vascular grafting materials. In this study, we have successfully fabricated well-defined nanopatterned cell culture substrates made of a biodegradable composite hydrogel consisting of poly(ethylene glycol) dimethacrylate (PEGDMA) and gelatin methacrylate (GelMA) by using UV-assisted capillary force lithography. The elasticity and degradation rate of the composite PEG-GelMA nanostructures were tuned by varying the ratios of PEGDMA and GelMA. Human umbilical vein endothelial cells (HUVECs) cultured on nanopatterned PEG-GelMA substrates exhibited enhanced cell attachment compared with those cultured on unpatterned PEG-GelMA substrates. Additionally, HUVECs cultured on nanopatterned PEG-GelM substrates displayed well-aligned, elongated morphology similar to that of native vascular endothelial cells and demonstrated rapid and directionally persistent migration. The ability to alter both substrate stiffness and degradation rate and culture endothelial cells with increased elongation and alignment is a promising next step in recapitulating the properties of native human vascular tissue for tissue engineering applications. PMID:24717683

  8. NANOSTRUCTURES nanostructures

    E-print Network

    Post, Olaf

    ­structures (including graphene and all types of single­wall nano­tubes) is provided. 1. Introduction Carbon nano­structures, in particular fullerenes (buckyballs), carbon nano­ tubes, and graphene have attracted a lot of attention operators on zig­zag carbon nano­tubes was conducted in [26, 27]. In this paper, we take a di#erent from [26

  9. Shock wave interactions with nano-structured materials: a molecular dynamics approach

    NASA Astrophysics Data System (ADS)

    Al-Qananwah, A. K.; Koplik, J.; Andreopoulos, Y.

    2013-02-01

    Porous materials have long been known to be effective in blast mitigation strategies. Nano-structured materials appear to have an even greater potential for blast mitigation because of their high surface-to-volume ratio, a geometric factor which substantially attenuates shock wave propagation. A molecular dynamics approach was used to explore the effects of this remarkable property on the behavior of traveling shocks impacting on solid materials. The computational setup included a moving piston, a gas region, and a target solid wall with and without a porous structure. The materials involved were represented by realistic interaction potentials. The results indicate that the presence of a nano-porous material layer in front of the target wall reduced the stress magnitude and the energy deposited inside the solid by about 30 %, while at the same time substantially decreasing the loading rate.

  10. Toward designer magnetite/polystyrene colloidal composite microspheres with controllable nanostructures and desirable surface functionalities.

    PubMed

    Xu, Shuai; Ma, Wan-Fu; You, Li-Jun; Li, Ju-Mei; Guo, Jia; Hu, Jack J; Wang, Chang-Chun

    2012-02-14

    An effective method was developed for synthesizing magnetite/polymer colloidal composite microspheres with controllable variations in size and shape of the nanostructures and desirable interfacial chemical functionalities, using surfactant-free seeded emulsion polymerization with magnetite (Fe(3)O(4)) colloidal nanocrystal clusters (CNCs) as the seed, styrene (St) as the monomer, and potassium persulfate (KPS) as the initiator. The sub-micrometer-sized citrate-acid-stabilized Fe(3)O(4) CNCs were first obtained via ethylene glycol (EG)-mediated solvothermal synthesis, followed by 3-(trimethoxysilyl)propyl methacrylate (MPS) modification to immobilize the active vinyl groups onto the surfaces, and then the hydrophobic St monomers were polymerized at the interfaces to form the polymer shells by seeded emulsion radical polymerization. The morphology of the composite microspheres could be controlled from raspberry- and flower-like shapes, to eccentric structures by simply adjusting the feeding weight ratio of the seed to the monomer (Fe(3)O(4)/St) and varying the amount of cross-linker divinyl benzene (DVB). The morphological transition was rationalized by considering the viscosity of monomer-swollen polymer matrix and interfacial tension between the seeds and polymer matrix. Functional groups, such as carboxyl, hydroxyl, and epoxy, can be facilely introduced onto the composite microspheres through copolymerization of St with other functional monomers. The resultant microspheres displayed a high saturation magnetization (46 emu/g), well-defined core-shell nanostructures, and surface chemical functionalities, as well as a sustained colloidal stability, promising for further biomedical applications. PMID:22288525

  11. Conductor-polymer composite electrode materials

    DOEpatents

    Ginley, D.S.; Kurtz, S.R.; Smyrl, W.H.; Zeigler, J.M.

    1984-06-13

    A conductive composite material useful as an electrode, comprises a conductor and an organic polymer which is reversibly electrochemically dopable to change its electrical conductivity. Said polymer continuously surrounds the conductor in intimate electrical contact therewith and is prepared by electrochemical growth on said conductor or by reaction of its corresponding monomer(s) on said conductor which has been pre-impregnated or pre-coated with an activator for said polymerization. Amount of the conductor is sufficient to render the resultant composite electrically conductive even when the polymer is in an undoped insulating state.

  12. Dielectric breakdown model for composite materials.

    PubMed

    Peruani, F; Solovey, G; Irurzun, I M; Mola, E E; Marzocca, A; Vicente, J L

    2003-06-01

    This paper addresses the problem of dielectric breakdown in composite materials. The dielectric breakdown model was generalized to describe dielectric breakdown patterns in conductor-loaded composites. Conducting particles are distributed at random in the insulating matrix, and the dielectric breakdown propagates according to new rules to take into account electrical properties and particle size. Dielectric breakdown patterns are characterized by their fractal dimension D and the parameters of the Weibull distribution. Studies are carried out as a function of the fraction of conducting inhomogeneities, p. The fractal dimension D of electrical trees approaches the fractal dimension of a percolation cluster when the fraction of conducting particles approximates the percolation limit. PMID:16241318

  13. Compression Testing of Textile Composite Materials

    NASA Technical Reports Server (NTRS)

    Masters, John E.

    1996-01-01

    The applicability of existing test methods, which were developed primarily for laminates made of unidirectional prepreg tape, to textile composites is an area of concern. The issue is whether the values measured for the 2-D and 3-D braided, woven, stitched, and knit materials are accurate representations of the true material response. This report provides a review of efforts to establish a compression test method for textile reinforced composite materials. Experimental data have been gathered from several sources and evaluated to assess the effectiveness of a variety of test methods. The effectiveness of the individual test methods to measure the material's modulus and strength is determined. Data are presented for 2-D triaxial braided, 3-D woven, and stitched graphite/epoxy material. However, the determination of a recommended test method and specimen dimensions is based, primarily, on experimental results obtained by the Boeing Defense and Space Group for 2-D triaxially braided materials. They evaluated seven test methods: NASA Short Block, Modified IITRI, Boeing Open Hole Compression, Zabora Compression, Boeing Compression after Impact, NASA ST-4, and a Sandwich Column Test.

  14. Poly(3-hexylthiophene) nanostructured materials for organic electronics applications.

    PubMed

    Bhatt, M P; Magurudeniya, H D; Rainbolt, E A; Huang, P; Dissanayake, D S; Biewer, M C; Stefan, M C

    2014-02-01

    Semiconducting polymers have been developed during the last few decades and are currently used in various organic electronics applications. Regioregular poly(3-hexylthiophene) (P3HT) is the most employed semiconducting polymer for organic electronics applications. The development of living Grignard metathesis polymerization (GRIM) allowed the synthesis of P3HT with well-defined molecular weights and functional end groups. A large number of block copolymers containing P3HT have been reported, and their opto-electronic properties have been investigated. The performance of P3HT homopolymer and block copolymers in field-effect transistors and bulk heterojunction solar cells are discussed in this review. The morphology of the P3HT materials is also discussed. PMID:24749411

  15. Nanostructure multilayer dielectric materials for capacitors and insulators

    DOEpatents

    Barbee, Jr., Troy W. (Palo Alto, CA); Johnson, Gary W. (Livermore, CA)

    1998-04-21

    A capacitor is formed of at least two metal conductors having a multilayer dielectric and opposite dielectric-conductor interface layers in between. The multilayer dielectric includes many alternating layers of amorphous zirconium oxide (ZrO.sub.2) and alumina (Al.sub.2 O.sub.3). The dielectric-conductor interface layers are engineered for increased voltage breakdown and extended service life. The local interfacial work function is increased to reduce charge injection and thus increase breakdown voltage. Proper material choices can prevent electrochemical reactions and diffusion between the conductor and dielectric. Physical vapor deposition is used to deposit the zirconium oxide (ZrO.sub.2) and alumina (Al.sub.2 O.sub.3) in alternating layers to form a nano-laminate.

  16. Nanostructured material for advanced energy storage : magnesium battery cathode development.

    SciTech Connect

    Sigmund, Wolfgang M. (University of Florida, Gainesville, FL); Woan, Karran V. (University of Florida, Gainesville, FL); Bell, Nelson Simmons

    2010-11-01

    Magnesium batteries are alternatives to the use of lithium ion and nickel metal hydride secondary batteries due to magnesium's abundance, safety of operation, and lower toxicity of disposal. The divalency of the magnesium ion and its chemistry poses some difficulties for its general and industrial use. This work developed a continuous and fibrous nanoscale network of the cathode material through the use of electrospinning with the goal of enhancing performance and reactivity of the battery. The system was characterized and preliminary tests were performed on the constructed battery cells. We were successful in building and testing a series of electrochemical systems that demonstrated good cyclability maintaining 60-70% of discharge capacity after more than 50 charge-discharge cycles.

  17. Multifunctional composite materials for catalysis and chemical mechanical planarization

    Microsoft Academic Search

    Cecil A. Coutinho

    2009-01-01

    Composite materials formed from two or more functionally different materials offer a versatile avenue to create a tailored material with well defined traits. Within this dissertation research, multi-functional composites were synthesized based on organic and inorganic materials. The functionally of these composites was experimentally tested and a semi-empirical model describing the sedimentation behavior of these particles was developed. This first

  18. Research Progress on Intercalation Composite Materials based on Kaolin

    Microsoft Academic Search

    Pan Xiaobing; Li Yanfeng; Liu Gang; Men Xuehu

    2004-01-01

    Kaolin is a nonmetal resource with abundant storage, and it would be changed into one of organic\\/inorganic composite materials by means of intercalating modification. Comparing with general composite materials, intercalation composite material is formed by intercalating one or more layers either organic molecules or polymers into inorganic materials with stratum shape, its mechanical properties could be modified markedly. The characteristics

  19. Reflective and magnetic properties of photonic polymer composite materials based on porous silicon and magnetite nanoparticles.

    PubMed

    Kim, Jihoon; Koh, Youngdae; Jang, Seunghyun; Jung, Kyoungsun; Woo, Hee-Gweon; Kim, Sungsoo; Sohn, Honglae

    2010-05-01

    Photonic polymer composite materials exhibiting both reflective and magnetic properties were prepared by the replication of rugate porous silicon (PS) using polystyrene and magnetite nanoparticle (Fe3O4). Rugate PS prepared by applying a computer-generated pseudo-sinusoidal current waveform resulted in a mirror with high reflectivity in a specific narrow spectral region and served as a template for replicating its nanostructure with polystyrene containing the magnetic nanoparticles of magnetite. The composite films replicated a sharp photonic resonance with full-width at half maximum (FWHM) of 20 nm from rugate PS in the reflectivity spectrum as well as displayed a magnetic property of magnetite nanoparticles in SQUID magnetometry. Optical characteristics of composite films indicated that the surface of polymer film had a negative structure of rugate PS. The composite films were stable in aqueous solutions for several days without any degradation. PMID:20358975

  20. Stressed environmental degradation of automotive composite materials

    SciTech Connect

    Henshaw, J.M.; Meyer, L.J. [Univ. of Tulsa, OK (United States); Houston, D.Q.; Hagerman, E.M.

    1997-12-31

    The degradation of mechanical properties due to exposure to various automotive environments during constant stress or constant strain loading is investigated. Two composites are studied. Each is a polyurethane reinforced with continuous strand E-glass mat, manufactured by the SRIM process. Novel fixtures apply tensile loads to dogbone-specimens while exposed to automotive fluids. After 300 hours, the specimens are tensile tested to failure in air. The effects of five fluids: distilled water, windshield washer fluid, brake fluid, gasoline, and sulfuric acid are examined on the first material. Extensive testing of both materials in distilled water gives a good comparison of the two materials and the effects of loading. Degradation in mechanical properties typically increases with stress level but is independent of the type of loading. This result is discussed in terms of damage and deformation mechanisms in the material.

  1. Novel Cryogenic Insulation Materials: Aerogel Composites

    NASA Technical Reports Server (NTRS)

    White, Susan

    2001-01-01

    New insulation materials are being developed to economically and reliably insulate future reusable spacecraft cryogenic tanks over a planned lifecycle of extreme thermal challenges. These insulation materials must prevent heat loss as well as moisture and oxygen condensation on the cryogenic tanks during extended groundhold, must withstand spacecraft launch conditions, and must protect a partly full or empty reusable cryogenic tank from significant reentry heating. To perform over such an extreme temperature range, novel composites were developed from aerogels and high-temperature matrix material such as Space Shuttle tile. These materials were fabricated and tested for use both as cryogenic insulation and as high-temperature insulation. The test results given in this paper were generated during spacecraft re-entry heating simulation tests using cryogenic cooling.

  2. Using Composite Materials in a Cryogenic Pump

    NASA Technical Reports Server (NTRS)

    Batton, William D.; Dillard, James E.; Rottmund, Matthew E.; Tupper, Michael L.; Mallick, Kaushik; Francis, William H.

    2008-01-01

    Several modifications have been made to the design and operation of an extended-shaft cryogenic pump to increase the efficiency of pumping. In general, the efficiency of pumping a cryogenic fluid is limited by thermal losses which is itself caused by pump inefficiency and leakage of heat through the pump structure. A typical cryogenic pump includes a drive shaft and two main concentric static components (an outer pressure containment tube and an intermediate static support tube) made from stainless steel. The modifications made include replacement of the stainless-steel drive shaft and the concentric static stainless-steel components with components made of a glass/epoxy composite. The leakage of heat is thus reduced because the thermal conductivity of the composite is an order of magnitude below that of stainless steel. Taking advantage of the margin afforded by the decrease in thermal conductivity, the drive shaft could be shortened to increase its effective stiffness, thereby increasing the rotordynamic critical speeds, thereby further making it possible to operate the pump at a higher speed to increase pumping efficiency. During the modification effort, an analysis revealed that substitution of the shorter glass/epoxy shaft for the longer stainless-steel shaft was not, by itself, sufficient to satisfy the rotordynamic requirements at the desired increased speed. Hence, it became necessary to increase the stiffness of the composite shaft. This stiffening was accomplished by means of a carbon-fiber-composite overwrap along most of the length of the shaft. Concomitantly with the modifications described thus far, it was necessary to provide for joining the composite-material components with metallic components required by different aspects of the pump design. An adhesive material formulated specially to bond the composite and metal components was chosen as a means to satisfy these requirements.

  3. Immobilization of lipase and keratinase on functionalized SBA-15 nanostructured materials

    NASA Astrophysics Data System (ADS)

    Le, Hy G.; Vu, Tuan A.; Tran, Hoa T. K.; Dang, Phuong T.

    2013-12-01

    SBA-15 nanostructured materials were synthesized via hydrothermal treatment and were functionalized with 3- aminopropyltriethoxysilane (APTES). The obtained samples were characterized by different techniques such as XRD, BET, TEM, IR and DTA. After functionalization, it showed that these nanostrucrured materials still maintained the hexagonal pore structure of the parent SBA-15. The model enzyms chosen in this study were lipase and keratinase. Lipase was a biocatalyst for hydrolyzation of long chain triglycerides or methyl esters of long chain alcohols and fatty acids; keratinase is a proteolytic enzyme that catalyzes the cleavage of keratin. The functionalized SBA-15 materials were used to immobilize lipase and keratinase, exhibiting higher activity than that of the unfunctionalized pure silica SBA-15 ones. This might be due to the enhancing of surface hydrophobicity upon functionalization. The surface functionalization of the nanostructured silicas with organic groups can favor the interaction between enzyme and the supports and consequently increasing the operational stability of the immobilized enzymes. The loading of lipase on functionalized SBA-15 materials was higher than that of keratinase. This might be rationalized by the difference in size of enzyms.

  4. Nonequilibrium molecular dynamics for bulk materials and nanostructures

    NASA Astrophysics Data System (ADS)

    Dayal, Kaushik; James, Richard D.

    2010-02-01

    We describe a method of constructing exact solutions of the equations of molecular dynamics in non-equilibrium settings. These solutions correspond to some viscometric flows, and to certain analogs of viscometric flows for fibers and membranes that have one or more dimensions of atomic scale. This work generalizes the method of objective molecular dynamics (OMD) ( Dumitric? and James, 2007). It allows us to calculate viscometric properties from a molecular-level simulation in the absence of a constitutive equation, and to relate viscometric properties directly to molecular properties. The form of the solutions is partly independent of the form of the force laws between atoms, and therefore these solutions have implications for coarse-grained theories. We show that there is an exact reduction of the Boltzmann equation corresponding to one family of OMD solutions. This reduction includes most known exact solutions of the equations of the moments for special kinds of molecules and gives the form of the molecular density function corresponding to such flows. This and other consequences leads us to propose an addition to the principle of material frame indifference, a cornerstone of nonlinear continuum mechanics. The method is applied to the failure of carbon nanotubes at an imposed strain rate, using the Tersoff potential for carbon. A large set of simulations with various strain rates, initial conditions and two choices of fundamental domain (unit cell) give the following unexpected results: Stone-Wales defects play no role in the failure (though Stone-Wales partials are sometimes seen just prior to failure), a variety of failure mechanisms is observed, and most simulations give a strain at failure of 15-20%, except those done with initial temperature above about 1200 K and at the lower strain rates. The latter have a strain at failure of 1-2%.

  5. Advanced Technology Composite Fuselage - Materials and Processes

    NASA Technical Reports Server (NTRS)

    Scholz, D. B.; Dost, E. F.; Flynn, B. W.; Ilcewicz, L. B.; Nelson, K. M.; Sawicki, A. J.; Walker, T. H.; Lakes, R. S.

    1997-01-01

    The goal of Boeing's Advanced Technology Composite Aircraft Structures (ATCAS) program was to develop the technology required for cost and weight efficient use of composite materials in transport fuselage structure. This contractor report describes results of material and process selection, development, and characterization activities. Carbon fiber reinforced epoxy was chosen for fuselage skins and stiffening elements and for passenger and cargo floor structures. The automated fiber placement (AFP) process was selected for fabrication of monolithic and sandwich skin panels. Circumferential frames and window frames were braided and resin transfer molded (RTM'd). Pultrusion was selected for fabrication of floor beams and constant section stiffening elements. Drape forming was chosen for stringers and other stiffening elements. Significant development efforts were expended on the AFP, braiding, and RTM processes. Sandwich core materials and core edge close-out design concepts were evaluated. Autoclave cure processes were developed for stiffened skin and sandwich structures. The stiffness, strength, notch sensitivity, and bearing/bypass properties of fiber-placed skin materials and braided/RTM'd circumferential frame materials were characterized. The strength and durability of cocured and cobonded joints were evaluated. Impact damage resistance of stiffened skin and sandwich structures typical of fuselage panels was investigated. Fluid penetration and migration mechanisms for sandwich panels were studied.

  6. Alkali metal protective garment and composite material

    SciTech Connect

    Ballif, J.L.; Yuan, W.W.

    1980-09-16

    A protective garment and composite material providing satisfactory heat resistance and physical protection for articles and personnel exposed to hot molten alkali metals, such as sodium are described. Physical protection is provided by a continuous layer of nickel foil. Heat resistance is provided by an underlying backing layer of thermal insulation. Overlying outer layers of fireproof woven ceramic fibers are used to protect the foil during storage and handling.

  7. Mechanics Methodology for Textile Preform Composite Materials

    NASA Technical Reports Server (NTRS)

    Poe, Clarence C., Jr.

    1996-01-01

    NASA and its contractors have completed a program to develop a basic mechanics underpinning for textile composites. Three major deliverables were produced by the program: 1. A set of test methods for measuring material properties and design allowables; 2. Mechanics models to predict the effects of the fiber preform architecture and constituent properties on engineering moduli, strength, damage resistance, and fatigue life; and 3. An electronic data base of coupon type test data. This report describes these three deliverables.

  8. Fiber Reinforced Composite Materials Used for Tankage

    NASA Technical Reports Server (NTRS)

    Cunningham, Christy

    2005-01-01

    The Nonmetallic Materials and Processes Group is presently working on several projects to optimize cost while providing effect materials for the space program. One factor that must be considered is that these materials must meet certain weight requirements. Composites contribute greatly to this effort. Through the use of composites the cost of launching payloads into orbit will be reduced to one-tenth of the current cost. This research project involved composites used for aluminum pressure vessels. These tanks are used to store cryogenic liquids during flight. The tanks need some type of reinforcement. Steel was considered, but added too much weight. As a result, fiber was chosen. Presently, only carbon fibers with epoxy resin are wrapped around the vessels as a primary source of reinforcement. Carbon fibers are lightweight, yet high strength. The carbon fibers are wet wound onto the pressure vessels. This was done using the ENTEC Filament Winding Machine. It was thought that an additional layer of fiber would aid in reinforcement as well as containment and impact reduction. Kevlar was selected because it is light weight, but five times stronger that steel. This is the same fiber that is used to make bullet-proof vests trampolines, and tennis rackets.

  9. Impact of solids on composite materials

    NASA Technical Reports Server (NTRS)

    Bronson, Arturo; Maldonado, Jerry; Chern, Tzong; Martinez, Francisco; Mccord-Medrano, Johnnie; Roschke, Paul N.

    1987-01-01

    The failure modes of composite materials as a result of low velocity impact were investigated by simulating the impact with a finite element analysis. An important facet of the project is the modeling of the impact of a solid onto cylindrical shells composed of composite materials. The model under development will simulate the delamination sustained when a composite material encounters impact from another rigid body. The computer equipment was installed, the computer network tested, and a finite element method model was developed to compare results with known experimental data. The model simulated the impact of a steel rod onto a rotating shaft. Pre-processing programs (GMESH and TANVEL) were developed to generate node and element data for the input into the three dimensional, dynamic finite element analysis code (DYNA3D). The finite element mesh was configured with a fine mesh near the impact zone and a coarser mesh for the impacting rod and the regions surrounding the impacting zone. For the computer simulation, five impacting loads were used to determine the time history of the stresses, the scribed surface areas, and the amount of ridging. The processing time of the computer codes amounted from 1 to 4 days. The calculated surface area were within 6-12 percent, relative error when compated to the actual scratch area.

  10. Plasma-based ion implantation: a valuable technology for the elaboration of innovative materials and nanostructured thin films

    NASA Astrophysics Data System (ADS)

    Vempaire, D.; Pelletier, J.; Lacoste, A.; Béchu, S.; Sirou, J.; Miraglia, S.; Fruchart, D.

    2005-05-01

    Plasma-based ion implantation (PBII), invented in 1987, can now be considered as a mature technology for thin film modification. After a brief recapitulation of the principle and physics of PBII, its advantages and disadvantages, as compared to conventional ion beam implantation, are listed and discussed. The elaboration of thin films and the modification of their functional properties by PBII have already been achieved in many fields, such as microelectronics (plasma doping/PLAD), biomaterials (surgical implants, bio- and blood-compatible materials), plastics (grafting, surface adhesion) and metallurgy (hard coatings, tribology), to name a few. The major advantages of PBII processing lie, on the one hand, in its flexibility in terms of ion implantation energy (from 0 to 100 keV) and operating conditions (plasma density, collisional or non-collisional ion sheath), and, on the other hand, in the easy transferrability of processes from the laboratory to industry. The possibility of modifying the composition and physical nature of the films, or of drastically changing their physical properties over several orders of magnitude makes this technology very attractive for the elaboration of innovative materials, including metastable materials, and the realization of micro- or nanostructures. A review of the state of the art in these domains is presented and illustrated through a few selected examples. The perspectives opened up by PBII processing, as well as its limitations, are discussed.

  11. One-dimensional nanostructured materials for lithium-ion battery and supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Chan, Candace Kay

    The need for improved electrochemical storage devices has necessitated research on new and advanced electrode materials. One-dimensional nanomaterials such as nanowires, nanotubes, and nanoribbons, can provide a unique opportunity to engineer electrochemical devices to have improved electronic and ionic conductivity as well as electrochemical and structural transformations. Silicon and germanium nanowires (NWs) were studied as negative electrode materials for lithiumion batteries because of their ability to alloy with large amounts of lithium, leading to 4-10 times higher specific capacities than the graphite standard. These nanowires could be grown vertically off of metallic current collector substrates using the gold-catalyzed vapor-liquid-solid synthesis. Electrochemical measurements of the SiNWs showed that capacities greater than 3,500 mAh/g could be obtained for tens of cycles, while hundreds of cycles could be obtained at lower capacities. As opposed to bulk Si, the SiNWs were observed to maintain their morphology during cycling and did not pulverize due to the large volume changes. Detailed TEM and XRD characterization showed that the SiNWs became amorphous during the first lithiation (charge) and formed a two-phase region between crystalline Si and amorphous Li xSi. Afterwards, the SiNWs remained amorphous and subsequent reaction was through a single-phase cycling of amorphous Si. The good cycling behavior compared to bulk and micron-sized Si particles was attributed to the nanowire morphology and electrode design. The surface chemistry and solid-electrolyte interphase (SEI) were studied using XPS as a function of charge and discharge potential. The common reduction productions expected in the electrolyte (1 M LiPF6 in 1:1 EC/DEC) were observed, with the main component being Li2CO3. The morphology of the SEI was found to change at different potentials, indicating a dynamic process involving deposition, dissolution, and re-deposition on the SiNWs. Longterm cycling performance of the SiNWs in different electrolytes, with various surface modifications and coatings, and other experimental parameters were evaluated. The electrochemical reaction of GeNWs with lithium resulted in capacities of ˜1000 mAh/g for tens of cycles. The GeNWs were also observed to become amorphous after the first charge. Interestingly, very large irreversible capacities were observed in the GeNWs, indicating surface instabilities or reactivity with the electrolyte. To passivate the surface, a thin layer of amorphous Si was used to coat the GeNWs and make Ge-Si coreshell nanowires. This passivation helped to reduce the irreversibly capacity loss and gave reversible capacities typical for the GeNWs. Two positive electrode materials for Li-ion batteries were synthesized in nano-morphologies and characterized. Transformation of layered structured V2O5 nanoribbons into the fully lithiated o-Li 3V2O5 phase was found to depend not only on the width but also the thickness of the nanoribbons. For the first time, complete delithiation of o-Li3V2O5 back to the single-crystalline, pristine V2O5 nanoribbon was observed, indicating a 30% higher energy density. Nanostructured BiOCl, a conversion material, was also synthesized and characterized for its Li insertion properties. Networks of silver nanowires (AgNWs) and single-walled carbon nanotubes (SWNTs) were explored as highly conducting, high surface area, and printable materials for flexible, light-weight supercapacitors. Use of the solution-processible AgNWs and SWNTs, as well as a polymer electrolyte, facilitated the fabrication of an entirely printable device on plastic substrates. The devices showed promising results for high energy and power density supercapacitors, with energy and power densities reaching 24 Wh/kg and 42 kW/kg for the AgNW/SWNT composite.

  12. Industry to Education Technical Transfer Program & Composite Materials. Composite Materials Course. Fabrication I Course. Fabrication II Course. Composite Materials Testing Course. Final Report.

    ERIC Educational Resources Information Center

    Massuda, Rachel

    These four reports provide details of projects to design and implement courses to be offered as requirements for the associate degree program in composites and reinforced plastics technology. The reports describe project activities that led to development of curricula for four courses: composite materials, composite materials fabrication I,…

  13. Electrospray neutralization process and apparatus for generation of nano-aerosol and nano-structured materials

    DOEpatents

    Bailey, Charles L. (Cross Junction, VA); Morozov, Victor (Manassas, VA); Vsevolodov, Nikolai N. (Kensington, MD)

    2010-08-17

    The claimed invention describes methods and apparatuses for manufacturing nano-aerosols and nano-structured materials based on the neutralization of charged electrosprayed products with oppositely charged electrosprayed products. Electrosprayed products include molecular ions, nano-clusters and nano-fibers. Nano-aerosols can be generated when neutralization occurs in the gas phase. Neutralization of electrospan nano-fibers with molecular ions and charged nano-clusters may result in the formation of fibrous aerosols or free nano-mats. Nano-mats can also be produced on a suitable substrate, forming efficient nano-filters.

  14. Phase evolution in carbide dispersion strengthened nanostructured copper composite by high energy ball milling

    NASA Astrophysics Data System (ADS)

    Hussain, Zuhailawati; Nur Hawadah, M. S.

    2012-09-01

    In this study, high-energy ball milling was applied to synthesis in situ nanostructured copper based composite reinforced with metal carbides. Cu, M (M=W or Ti) and graphite powder mixture were mechanically alloyed for various milling time in a planetary ball mill with composition of Cu-20vol%WC and Cu-20vol%TiC. Then the as-milled powder were compacted at 200 to 400 MPa and sintered in a vacuum furnace at 900°C. The results of X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis showed that formation of tungsten carbides (W2C and WC phases) was observed after sintering of Cu-W-C mixture while TiC precipitated in as-milled powder of Cu-Ti-C composite after 5 h and become amorphous with longer milling. Mechanism of MA explained the cold welding and fracturing event during milling. Cu-W-C system shows fracturing event is more dominant at early stage of milling and W particle still existed after milling up to 60 h. While in Cu-Ti-C system, cold welding is more dominant and all Ti particles dissolved into Cu matrix.

  15. Phase evolution in carbide dispersion strengthened nanostructured copper composite by high energy ball milling

    SciTech Connect

    Hussain, Zuhailawati; Nur Hawadah, M. S. [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2012-09-06

    In this study, high-energy ball milling was applied to synthesis in situ nanostructured copper based composite reinforced with metal carbides. Cu, M (M=W or Ti) and graphite powder mixture were mechanically alloyed for various milling time in a planetary ball mill with composition of Cu-20vol%WC and Cu-20vol%TiC. Then the as-milled powder were compacted at 200 to 400 MPa and sintered in a vacuum furnace at 900 Degree-Sign C. The results of X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis showed that formation of tungsten carbides (W{sub 2}C and WC phases) was observed after sintering of Cu-W-C mixture while TiC precipitated in as-milled powder of Cu-Ti-C composite after 5 h and become amorphous with longer milling. Mechanism of MA explained the cold welding and fracturing event during milling. Cu-W-C system shows fracturing event is more dominant at early stage of milling and W particle still existed after milling up to 60 h. While in Cu-Ti-C system, cold welding is more dominant and all Ti particles dissolved into Cu matrix.

  16. Dimensional dependence of photomechanical response in carbon nanostructure composites: a case for carbon-based mixed-dimensional systems.

    PubMed

    Loomis, James; Panchapakesan, Balaji

    2012-06-01

    This paper reports dimensional dependence of the mechanical response in carbon nanostructure composites to near-infrared (NIR) light. Using polydimethylsiloxane, a common silicone elastomer, composites were fabricated with one-dimensional multi-wall carbon nanotubes (MWNTs), two-dimensional single-layer graphene, two-and-a-half-dimensional graphene nanoplatelets and three-dimensional highly ordered pyrolytic graphite. An evaporative mixing technique was utilized to achieve homogeneous dispersions of carbon in the polymer composites, and their photomechanical responses to NIR illumination were studied. For a given carbon concentration, both steady-state photomechanical stress response and energy conversion efficiency were found to be directly related to the dimensional state of the carbon nanostructure additive. A maximum observed stress change of ~60 kPa and ~5 × 10(-3)% efficiency were obtained with just 1 wt% MWNT loading. Actuation and relaxation kinetic responses were found to be related not to dimensionality, but to the percolation threshold of the carbon nanostructure additive in the polymer. Establishing a connective network of the carbon nanostructure additive allowed for energy transduction responsible for the photomechanical effect to activate carbon beyond the NIR illumination point, resulting in enhanced actuation. For samples greater than percolation threshold, photoconductivity of the nanocomposite structure as a function of applied pre-strain was measured. Photoconductive response was found to be inversely proportional to applied pre-strain, demonstrating mechanical coupling. Mechanical response dependence to the carbon nanostructure dimensional state could have significance in developing new types of carbon-based mixed-dimensional composites for sensor and actuator systems. PMID:22551654

  17. Use of advanced composite materials for innovative building design solutions/

    E-print Network

    Lau, Tak-bun, Denvid

    2009-01-01

    Advanced composite materials become popular in construction industry for the innovative building design solutions including strengthening and retrofitting of existing structures. The interface between different materials ...

  18. Bottom-up nanostructured bulk silicon: a practical high-efficiency thermoelectric material.

    PubMed

    Yusufu, Aikebaier; Kurosaki, Ken; Miyazaki, Yoshinobu; Ishimaru, Manabu; Kosuga, Atsuko; Ohishi, Yuji; Muta, Hiroaki; Yamanaka, Shinsuke

    2014-11-21

    The effectiveness of thermoelectric (TE) materials is quantified by the dimensionless figure of merit (zT). An ideal way to enhance zT is by scattering phonons without scattering electrons. Here we show that, using a simple bottom-up method, we can prepare bulk nanostructured Si that exhibits an exceptionally high zT of 0.6 at 1050 K, at least three times higher than that of the optimized bulk Si. The nanoscale precipitates in this material connected coherently or semi-coherently with the Si matrix, effectively scattering heat-carrying phonons without significantly influencing the material's electron transport properties, leading to the high zT. PMID:25311105

  19. Composite materials for thermal energy storage

    DOEpatents

    Benson, David K. (Golden, CO); Burrows, Richard W. (Conifer, CO); Shinton, Yvonne D. (Northglenn, CO)

    1986-01-01

    The present invention discloses composite material for thermal energy storage based upon polyhydric alcohols, such as pentaerythritol, trimethylol ethane (also known as pentaglycerine), neopentyl glycol and related compounds including trimethylol propane, monoaminopentaerythritol, diamino-pentaerythritol and tris(hydroxymethyl)acetic acid, separately or in combinations, which provide reversible heat storage through crystalline phase transformations. These phase change materials do not become liquid during use and are in contact with at least one material selected from the group consisting of metals, carbon siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, porous rock, and mixtures thereof. Particulate additions, such as aluminum or graphite powders, as well as metal and carbon fibers can also be incorporated therein. Particulate and/or fibrous additions can be introduced into molten phase change materials which can then be cast into various shapes. After the phase change materials have solidified, the additions will remain dispersed throughout the matrix of the cast solid. The polyol is in contact with at least one material selected from the group consisting of metals, carbon siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, and mixtures thereof.

  20. Development of collagen-hydroxyapatite nanostructured composites via a calcium phosphate precursor mechanism

    NASA Astrophysics Data System (ADS)

    Jee, Sang Soo

    Bone is an interpenetrating inorganic/organic composite that consists of mineralized collagen fibrils, which is hierarchically organized into various structures. The structure of mineralized collagen fibril, in which nano-crystals of hydroxyapatite are embedded within the collagen fibrils, provides remarkable mechanical and bio-resorptive properties. Therefore, there have been many attempts to produce collagen-hydroxyapatite composites having a bone-like structure. However, duplication of even the most fundamental level of bone structure has not been easily achieved by conventional nucleation and growth techniques, which are based on the most widely accepted hypothesis of bone mineralization. In nature, the collagen fibril is mineralized via intrafibrillar mineralization, which produces preferentially oriented hydroxyapatite nano-crystals occupying the interstices in collagen fibrils. Our group has demonstrated that intrafibrillar mineralization can be achieved by using a new method based on the Polymer-Induced Liquid-Precursor (PILP) mineralization process. In the PILP process, a poly-anionic additive can produce an amorphous calcium phosphate precursor which enables us to achieve intrafibrillar mineralization of collagen. It is thought that the precursor is pulled into the interstices of the collagen fibrils via capillary forces, and upon solidification and crystallization of the precursor produces an interpenetrating composite with the nanostructured architecture of bone. In this dissertation, to demonstrate the effectiveness of the PILP process on the intrafibrillar mineralization of collagen fibril, various collagen scaffolds, such as turkey tendon, bovine tendon and synthetic collagen sponge, were mineralized by the PILP process. Various poly-aspartates with different molecular weight were also used for the optimization of the PILP process for the mineralization of the collagen scaffolds. With the systematic researches, we discovered that the molecular weight of poly-aspartic acid affects the degree of intrafibrillar mineralization of collagen scaffolds. High molecular weight poly-aspartic acid could produce a stable and dispersed amorphous precursor, leading to a high degree of intrafibrillar mineralization. The mineral content of the collagen sponge mineralized using high molecular weight poly-aspartic acid was equivalent to the mineral content of bone. According to X-ray diffraction analysis of the mineralized collagen, the size and composition of the intrafibrillar hydroxyapatite produced by the PILP process were almost identical to carbonated hydroxyapatite in bone. The selective area electron diffraction patterns indicated that the [001] direction of hydroxyapatite is roughly aligned along the c-axis of collagen fibril, leading to the formation 002 arcs. Using dark field imaging, it was possible to visualize the preferentially oriented hydroxyapatite in TEM. Thermal analysis of mineralized collagen also showed a reduction in the thermal stability of collagen, which is similar to that observed in the collagen in bone, due to the presence of intrafibrillar hydroxyapatite. Now, we confidently suggest that the PILP process can provide a new way to develop synthetic bone-like composites whose nano-structure is very close to the nano-structure of natural bone. Moreover, we hope that our successful intrafibrillar mineralization of collagen via the precursor mechanism revives discussion of hypothesis of bone mineralization via the amorphous calcium phosphate phase.

  1. Synergistic manipulation of micro-nanostructures and composition: anatase/rutile mixed-phase TiO2 hollow micro-nanospheres with hierarchical mesopores for photovoltaic and photocatalytic applications

    NASA Astrophysics Data System (ADS)

    Zhu, Qing; Qian, Jieshu; Pan, Hao; Tu, Luo; Zhou, Xingfu

    2011-09-01

    The construction of nanocrystals with controllable composition and desirable micro-nanostructures is a well-known challenge. A combination of favorable composition and optimized micro-nanostructures can enhance the performance of a material significantly. Using TiO2 as an example, we demonstrate here a facile approach to prepare anatase/rutile mixed-phase TiO2 hollow micro-nanospheres with hierarchical mesopores. Our strategy relies on polymer-assisted assembly of ~ 5 nm nano-building blocks into three-dimensional hierarchical hollow micro-nanospheres in a mixed alcohol-water solution. This superior micro-nanostructure endows the sample with hierarchical mesopores and a high surface area of 106 m2 g - 1. We also show that, due to the synergetic effects of the mixed-phase composition and the micro-nanostructures, the sample exhibited significantly improved photovoltaic performance and similar photocatalytic performance compared with the commercial Degussa P25. These results suggested that our sample has great potential for future photovoltaic and photocatalytic applications.

  2. Combustion synthesis of advanced composite materials

    SciTech Connect

    Moore, J.J. (Colorado School of Mines, Golden (United States))

    1993-01-01

    Self-propagating high temperature (combustion) synthesis (SHS), has been investigated as a means of producing both dense and expanded (foamed) ceramic and ceramic-metal composites, ceramic powders and whiskers. Several model exothermic combustion synthesis reactions were used to establish the importance of certain reaction parameters, e.g., stoichiometry, green density, combustion mode, particle size, etc. on the control of the synthesis reaction, product morphology and properties. The use of an in situ liquid infiltration technique and the effect of varying the reactants and their stoichiometry to provide a range of reactant and product species i.e., solids, liquids and gases, with varying physical properties e.g., volatility and thermal conductivity, on the microstructure and morphology of synthesized composite materials is discussed. Conducting the combustion synthesis reaction in a reactive gas environment to take advantage of the synergistic effects of combustion synthesis and vapor phase transport is also examined. 10 refs.

  3. Glasses, ceramics, and composites from lunar materials

    NASA Astrophysics Data System (ADS)

    Beall, George H.

    1992-02-01

    A variety of useful silicate materials can be synthesized from lunar rocks and soils. The simplest to manufacture are glasses and glass-ceramics. Glass fibers can be drawn from a variety of basaltic glasses. Glass articles formed from titania-rich basalts are capable of fine-grained internal crystallization, with resulting strength and abrasion resistance allowing their wide application in construction. Specialty glass-ceramics and fiber-reinforced composites would rely on chemical separation of magnesium silicates and aluminosilicates as well as oxides titania and alumina. Polycrystalline enstatite with induced lamellar twinning has high fracture toughness, while cordierite glass-ceramics combine excellent thermal shock resistance with high flexural strengths. If sapphire or rutile whiskers can be made, composites of even better mechanical properties are envisioned.

  4. Combustion synthesis of advanced composite materials

    NASA Technical Reports Server (NTRS)

    Moore, John J.

    1993-01-01

    Self-propagating high temperature (combustion) synthesis (SHS), has been investigated as a means of producing both dense and expanded (foamed) ceramic and ceramic-metal composites, ceramic powders and whiskers. Several model exothermic combustion synthesis reactions were used to establish the importance of certain reaction parameters, e.g., stoichiometry, green density, combustion mode, particle size, etc. on the control of the synthesis reaction, product morphology and properties. The use of an in situ liquid infiltration technique and the effect of varying the reactants and their stoichiometry to provide a range of reactant and product species i.e., solids, liquids and gases, with varying physical properties e.g., volatility and thermal conductivity, on the microstructure and morphology of synthesized composite materials is discussed. Conducting the combustion synthesis reaction in a reactive gas environment to take advantage of the synergistic effects of combustion synthesis and vapor phase transport is also examined.

  5. Synthesis of hard nano-structured metal matrix composite boride coatings using combined laser and sol–gel technology

    Microsoft Academic Search

    A Roy Choudhury; Tamer Ezz; Lin Li

    2007-01-01

    This paper reports the synthesis of nano-structured boride metal matrix composite (MMC) coatings obtained by laser melting of a pre-placed mixture of B4C+Ti–6Al–4V powders and sol–gel derived nano-particulate Ti(OH)4. The resulting nano-composite coatings have been characterised in terms of microhardness, microstructure and constituent phase composition. The coatings show evidence of micro-level FeB phases and nano-particulate TiB phases in a (Fe+Fe2B)

  6. Nanostructured hybrid layered-spinel cathode material synthesized by hydrothermal method for lithium-ion batteries.

    PubMed

    Liu, Cong; Wang, Zhiyuan; Shi, Chunsheng; Liu, Enzuo; He, Chunnian; Zhao, Naiqin

    2014-06-11

    Nanostructured spinel LiMn1.5Ni0.5O4, layered Li1.5Mn0.75Ni0.25O2.5 and layered-spinel hybrid particles have been successfully synthesized by hydrothermal methods. It is found that the nanostructured hybrid cathode contains both spinel and layered components, which could be expressed as Li1.13Mn0.75Ni0.25O2.32. Diffraction-contrast bright-field (BF) and dark-field (DF) images illustrate that the hybrid cathode has well dispersed spinel component. Electrochemical measurements reveal that the first-cycle efficiency of the layered-spinel hybrid cathode is greatly improved (up to 90%) compared with that of the layered material (71%) by integrating spinel component. Our investigation demonstrates that the spinel containing hybrid material delivers a high capacity of 240 mAh g(-1) with good cycling stability between 2.0 and 4.8 V at a current rate of 0.1 C. PMID:24828946

  7. Composite materials for thermal energy storage

    DOEpatents

    Benson, D.K.; Burrows, R.W.; Shinton, Y.D.

    1985-01-04

    A composite material for thermal energy storage based upon polyhydric alcohols, such as pentaerythritol, trimethylol ethane (also known as pentaglycerine), neopentyl glycol and related compounds including trimethylol propane, monoaminopentaerythritol, diamino-pentaerythritol and tris(hydroxymethyl)acetic acid, separately or in combinations, which provide reversible heat storage through crystalline phase transformations. These PCM's do not become liquid during use and are in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, porous rock, and mixtures thereof. Particulate additions such as aluminum or graphite powders, as well as metal and carbon fibers can also be incorporated therein. Particulate and/or fibrous additions can be introduced into molten phase change materials which can then be cast into various shapes. After the phase change materials have solidified, the additions will remain dispersed throughout the matrix of the cast solid. The polyol is in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, and mixtures thereof.

  8. Temporal Evolution of the Nanostructure and Phase Compositions in a Model Ni-Al-Cr Alloy

    NASA Technical Reports Server (NTRS)

    Sudbrack, Chantal K.; Yoon, Kevin E.; Seidman, David N.; Seidman, David N.

    2006-01-01

    In a Ni-5.2 Al-14.2 Cr at.% alloy with moderate solute supersaturations and a very small gamma/gamma prime lattice parameter misfit, the nanostructural and compositional pathways during gamma prime(L12) precipitation at 873 K are investigated using atom-probe tomography, conventional transmission electron microscopy, and hardness measurements. Nucleation of high number densities (N(sub v) greater than 10(sup 23) per cubic meters) of solute-rich precipitates (mean radius = [R] = 0.75 nm), with a critical nucleus composition of Ni-18.3 plus or minus 0.9 Al-9.3 plus or minus 0.7 Cr at.%, initiates between 0.0833 and 0.167 h. With increasing aging time (a) the solute concentrations decay in spheroidal precipitates ([R] less than 10 nm); (b) the observed early-stage coalescence peaks at maximum N(sub v) in coincidence with the smallest interprecipitate spacing; and (c) the reaction enters a quasi-stationary regime where growth and coarsening operate concomitantly. During this quasi-stationary regime, the c (face-centered cubic)-matrix solute supersaturations decay with a power-law dependence of about -1/3, while the dependencies of [R] and N(sub v) are 0.29 plus or minus 0.05 and -0.64 plus or minus 0.06 at a coarsening rate slower than model predications. Coarsening models allow both equilibrium phase compositions to be determined from the compositional measurements. The observed early-stage coalescence is discussed in further detail.

  9. In vivo and in vitro investigations of a nanostructured coating material - a preclinical study.

    PubMed

    Adam, Martin; Ganz, Cornelia; Xu, Weiguo; Sarajian, Hamid-Reza; Götz, Werner; Gerber, Thomas

    2014-01-01

    Immediate loading of dental implants is only possible if a firm bone-implant anchorage at early stages is developed. This implies early and high bone apposition onto the implant surface. A nanostructured coating material based on an osseoinductive bone grafting is investigated in relation to the osseointegration at early stages. The goal is to transmit the structure (silica matrix with embedded hydroxyapatite) and the properties of the bone grafting into a coating material. The bone grafting substitute offers an osseoinductive potential caused by an exchange of the silica matrix in vivo accompanied by vascularization. X-ray diffraction and transmission electron microscopy analysis show that the coating material consists of a high porous silica matrix with embedded nanocrystalline hydroxyapatite with the same morphology as human hydroxyapatite. An in vitro investigation shows the early interaction between coating and human blood. Energy-dispersive X-ray analysis showed that the silica matrix was replaced by an organic matrix within a few minutes. Uncoated and coated titanium implants were inserted into the femora of New Zealand White rabbits. The bone-to-implant contact (BIC) was measured after 2, 4, and 6 weeks. The BIC of the coated implants was increased significantly at 2 and 4 weeks. After 6 weeks, the BIC was decreased to the level of the control group. A histological analysis revealed high bone apposition on the coated implant surface after 2 and 4 weeks. Osteoblastic and osteoclastic activities on the coating material indicated that the coating participates in the bone-remodeling process. The nanostructure of the coating material led to an exchange of the silica matrix by an autologous, organic matrix without delamination of the coating. This is the key issue in understanding initial bone formation on a coated surface. PMID:24627631

  10. Estimating Weibull parameters for composite materials.

    NASA Technical Reports Server (NTRS)

    Robinson, E. Y.

    1972-01-01

    This paper deals with the statistical analysis of strength and fracture of materials in general, with application to fiber composites. The 'weakest link' model is considered in a fairly general form, and the resulting equations are demonstrated by using a Weibull distribution for flaws. This distribution appears naturally in a variety of problems, and therefore additional attention is devoted to analysis and statistical estimation connected with this distribution. Special working charts are included to facilitate interpretation of observed data and estimation of parameters. Implications of the size effect are considered for various kinds of flaw distributions. The paper describes failure and damage in a fiber-reinforced systems.

  11. Photochemical decoration of magnetic composites with silver nanostructures for determination of creatinine in urine by surface-enhanced Raman spectroscopy.

    PubMed

    Alula, Melisew Tadele; Yang, Jyisy

    2014-12-01

    In this study, silver nanostructures decorated magnetic nanoparticles for surface-enhanced Raman scattering (SERS) measurements were prepared via photoreduction utilizing the catalytic activity of ZnO nanostructure. The ZnO/Fe3O4 composite was first prepared by dispersing pre-formed magnetic nanoparticles into alkaline zinc nitrate solutions. After annealing of the precipitates, the formed ZnO/Fe3O4 composites were successfully decorated with silver nanostructures by soaking the composites into silver nitrate/ethylene glycol solution following UV irradiations. To find the optimal condition when preparing Ag@ZnO/Fe3O4 composites for SERS measurements, factors such as the reaction conditions, photoreduction time, concentration of zinc nitrate and silver nitrate were studied. Results indicated that the photoreduction efficiency was significantly improved with the assistance of ZnO but the amount of ZnO in the composite is not critical. The concentration of silver nitrate and UV irradiation time affected the morphologies of the formed composites and optimal condition in preparation of the composites for SERS measurement was found using 20mM of silver nitrate with an irradiation time of 90 min. Under the optimized condition, the obtained SERS intensities were highly reproducible with a SERS enhancement factor in the order of 7. Quantitative analyses showed that a linear range up to 1 µM with a detection limit lower than 0.1 µM in the detection of creatinine in aqueous solution could be obtained. Successful applying of these prepared composites to determine creatinine in urine sample was obtained. PMID:25159379

  12. Impact ignition of aluminum-teflon based energetic materials impregnated with nano-structured carbon additives

    NASA Astrophysics Data System (ADS)

    Kappagantula, Keerti; Pantoya, Michelle L.; Hunt, Emily M.

    2012-07-01

    The inclusion of graphene into composite energetic materials to enhance their performance is a new area of interest. Studies have shown that the addition of graphene significantly enhances the thermal transport properties of an energetic composite, but how graphene influences the composite's ignition sensitivity has not been studied. The objective of this study is to examine the influence of carbon additives in composite energetic material composed of aluminum and polytetrafluoroethylene (Teflon™) on ignition sensitivity due to low velocity, drop weight impact. Specifically, three forms of carbon additives were investigated and selected based on different physical and structural properties: spherically shaped amorphous nano particles of carbon, cylindrically shaped multi walled carbon nanotubes, and sheet like graphene flakes. Results show an interesting trend: composites consisting of carbon nanotubes are significantly more sensitive to impact ignition and require the lowest ignition energy. In contrast, graphene is least sensitive to ignition exhibiting negligible reduction in ignition energy with low concentrations of graphene additive. While graphene does not significantly sensitize the energetic composite to ignition, graphene does, however, result in greater overall reactivity as observed through images of the reaction. The enhanced thermal transport properties of graphene containing composites may promote greater energy transport once ignited, but those properties do not also increase ignition sensitivity. These results and the understanding of the structural arrangement of particles within a composite as a key parameter affecting impact ignition sensitivity will have an impact on the safe handling and use of composite energetic materials.

  13. High thermal conductivity epoxy-silver composites based on self-constructed nanostructured metallic networks

    NASA Astrophysics Data System (ADS)

    Pashayi, Kamyar; Fard, Hafez Raeisi; Lai, Fengyuan; Iruvanti, Sushumna; Plawsky, Joel; Borca-Tasciuc, Theodorian

    2012-05-01

    We demonstrate epoxy-silver nanoparticle composites with high thermal conductivity ? enabled by self-constructed nanostructured networks (SCNN) forming during the curing process at relatively low temperatures (150 °C). The networks formation mechanism involves agglomeration of the polyvinylpyrrolidone (PVP) coated nanoparticles, PVP removal, and sintering of the nanoparticles at suppressed temperatures induced by their small diameters (20-80 nm). Sintering and the SCNN formation are supported by differential scanning calorimetry and electron microscopy investigations. The formation of SCNN with high aspect ratio structures leads to enhancements in the measured thermal conductivity ? of the composite by more than two orders of magnitude versus the pure epoxy. However, ? enhancements are modest if microparticles (1.8-4.2 ?m) are employed instead of PVP coated nanoparticles. The ? trends are qualitatively explained using a percolating threshold thermal conductivity model for the microcomposites. For the nanocomposites the measured ? is ˜14% of the upper limit value predicted by the Hashin and Shtrikman (H-S) theory for an ideally connected network, a measure of the non-ideal network inside the nanocomposites.

  14. Morphological and structural characterization of SiC based composite nanostructures

    NASA Astrophysics Data System (ADS)

    Filipescu, M.; Stokker-Cheregi, F.; Colceag, D.; Nedelcea, A.; Birjega, R.; Nistor, L. C.; Dinescu, M.

    2013-08-01

    This paper reports on producing SiC based nanostructures (SiC, W-SiC, CNS-SiC) by pulsed laser deposition (PLD) and radio-frequency plasma assisted PLD. Simple and composite targets (SiC, 3/4 SiC + 1/4 tungsten and 3/4 SiC + 1/4 graphite) were irradiated by a 266 nm pulsed laser beam having a pulse duration of 7 ns. The silicon substrates were kept either at room temperature or heated up to 600 °C. The depositions were performed in argon at various pressures, ranging from 0.05 mbar up to 2 mbar. The influence of deposition parameters on the structure, surface morphology and composition of different SiC based structures was studied by atomic force microscopy, scanning electron microscopy, secondary ion mass spectrometry, transmission electron microscopy and selected area electron diffraction. Fibers, tubes, nanoparticles and rolled sheets structures were obtained by varying laser fluence, substrate temperature, gas pressure and radio-frequency power.

  15. Nano-structured polyaniline-ionic liquid composite film coated steel wire for headspace solid-phase microextraction of organochlorine pesticides in water

    Microsoft Academic Search

    Zhanqi Gao; Wenchao Li; Benzhi Liu; Feng Liang; Huan He; Shaogui Yang; Cheng Sun

    2011-01-01

    A novel nano-structured polyaniline-ionic liquid (i.e. 1-butyl-3-methylimidazolium hexafluorophosphate, BMIPF6) composite (BPAN) film coated steel wire was prepared by electrochemical deposition. Scanning electron microscopy images showed that the obtained porous BPAN coating consisted of nanofibers, whose diameter ranged from 50 to 80nm. Furthermore, the novel nano-structured composite coating was very stable at relatively high temperatures (up to 350°C) and it could

  16. Mild Synthesis Route to Nanostructured ?-MnO2 as Electrode Materials for Electrochemical Energy Storage

    NASA Astrophysics Data System (ADS)

    Zhang, Yuanjian; Xue, Dongfeng

    2012-09-01

    ?-MnO2 electrode materials with sphere-, rod- and flower-like nanostructures were for the first time fabricated by a redox reaction between KMnO4 and NaHSO3 in chemical bath. Crystal structure and morphology of the as-crystallized samples were characterized by X-ray diffraction and scanning electron microscopy. The influence of reaction temperature and H+ concentration on both morphology and crystalline nature was investigated. Their electrochemical behaviors were investigated by cycling voltammetry and galvanostatic charge/discharge measurements in a three-electrode glass cell. Depending upon different synthesis conditions of ?-MnO2 electrodes, their specific capacitance values varied in the range of 43 to 197 F g-1 at the current density of 1 A g-1. Moreover, their specific capacitance values decrease with increasing crystallinity and particle size. In this work, we conclude that the energy storage mechanism is closely related to the particle aggregation state of electrode materials.

  17. Highlights of The School of Materials

    E-print Network

    Lin, Zhiqun

    ) 2010 ­ Complete integration of all materials by merger of PTFE with Ceramics & Metallurgy, and measurements as our tools, we work on all materials forms including metals, ceramics, polymers, textiles, fibers, composites, nanostructures, & biomolecular solids We study material response under various

  18. Some strength properties of graphite-zirconium carbide composite materials

    Microsoft Academic Search

    V. S. Dergunova; A. N. Shurshakov; G. D. Posos'eva; L. N. Lutsenko

    1972-01-01

    1.Some factors influencing the strength of composite materials were examined.2.A study was made of the strength properties of graphite-zirconium carbide and graphite-zirconium carbide-zirconium composite materials having varying structures and compositions. It was found that, at 2500‡C, the tensile strength of TsG-25 type composite material is 30% higher than that of dense VPP constructional graphite.3.It was established that, by varying the

  19. Method for preparing dielectric composite materials

    DOEpatents

    Lauf, Robert J.; Anderson, Kimberly K.; Montgomery, Frederick C.; Collins, Jack L.; Felten, John J.

    2004-11-23

    The invention allows the fabrication of small, dense beads of dielectric materials with selected compositions, which are incorporated into a polymeric matrix for use in capacitors, filters, and the like. A porous, generally spherical bead of hydrous metal oxide containing titanium or zirconium is made by a sol-gel process to form a substantially rigid bead having a generally fine crystallite size and correspondingly finely distributed internal porosity. The resulting gel bead may be washed and hydrothermally reacted with a soluble alkaline earth salt (typically Ba or Sr) at elevated temperature and pressure to convert the bead into a mixed hydrous titanium- or zirconium-alkaline earth oxide while retaining the generally spherical shape. Alternatively, the gel bead may be made by coprecipitation. This mixed oxide bead is then washed, dried and calcined to produce the desired (BaTiO.sub.3, PbTiO.sub.3, SrZrO.sub.3) structure. The sintered beads are incorporated into a selected polymer matrix. The resulting dielectric composite material may be electrically "poled" if desired.

  20. Piezoelectric Nanoparticle-Polymer Composite Materials

    NASA Astrophysics Data System (ADS)

    McCall, William Ray

    Herein we demonstrate that efficient piezoelectric nanoparticle-polymer composite materials can be synthesized and fabricated into complex microstructures using sugar-templating methods or optical printing techniques. Stretchable foams with excellent tunable piezoelectric properties are created by incorporating sugar grains directly into polydimethylsiloxane (PDMS) mixtures containing barium titanate (BaTiO3 -- BTO) nanoparticles and carbon nanotubes (CNTs), followed by removal of the sugar after polymer curing. Porosities and elasticity are tuned by simply adjusting the sugar/polymer mass ratio and the electrical performance of the foams showed a direct relationship between porosity and the piezoelectric outputs. User defined 2D and 3D optically printed piezoelectric microstructures are also fabricated by incorporating BTO nanoparticles into photoliable polymer solutions such as polyethylene glycol diacrylate (PEGDA) and exposing to digital optical masks that can be dynamically altered. Mechanical-to-electrical conversion efficiency of the optically printed composite is enhanced by chemically altering the surface of the BTO nanoparticles with acrylate groups which form direct covalent linkages with the polymer matrix under light exposure. Both of these novel materials should find exciting uses in a variety of applications including energy scavenging platforms, nano- and microelectromechanical systems (NEMS/MEMS), sensors, and acoustic actuators.

  1. Synthesis and characterization of cyclotriphosphazenes containing silicon as single solid-state precursors for the formation of silicon/phosphorus nanostructured materials.

    PubMed

    Díaz, Carlos; Valenzuela, Maria Luisa; Bravo, Daniel; Lavayen, Vladimir; O'Dwyer, Colm

    2008-12-15

    The synthesis and characterization of new organosilicon derivatives of N(3)P(3)Cl(6), N(3)P(3)[NH(CH(2))(3)Si(OEt)(3)](6) (1), N(3)P(3)[NH(CH(2))(3)Si(OEt)(3)](3)[NCH(3)(CH(2))(3)CN](3) (2), and N(3)P(3)[NH(CH(2))(3)Si(OEt)(3)](3)[HOC(6)H(4)(CH(2))CN](3) (3) are reported. Pyrolysis of 1, 2, and 3 in air and at several temperatures results in nanostructured materials whose composition and morphology depend on the temperature of pyrolysis and the substituents of the phosphazenes ring. The products stem from the reaction of SiO(2) with P(2)O(5), leading to either crystalline Si(5)(PO(4))(6)O, SiP(2)O(7) or an amorphous phase as the glass Si(5)(PO(4))(6)O/3SiO(2).2P(2)O(5), depending on the temperature and nature of the trimer precursors. From 1 at 800 degrees C, core-shell microspheres of SiO(2) coated with Si(5)(PO(4))(6)O are obtained, while in other cases, mesoporous or dense structures are observed. Atomic force microscopy examination after deposition of the materials on monocrystalline silicon wafers evidences morphology strongly dependent on the precursors. Isolated islands of size approximately 9 nm are observed from 1, whereas dense nanostructures with a mean height of 13 nm are formed from 3. Brunauer-Emmett-Teller measurements show mesoporous materials with low surface areas. The proposed growth mechanism involves the formation of cross-linking structures and of vacancies by carbonization of the organic matter, where the silicon compounds nucleate. Thus, for the first time, unique silicon nanostructured materials are obtained from cyclic phosphazenes containing silicon. PMID:18975936

  2. Nanostructured pseudocapacitive materials decorated 3D graphene foam electrodes for next generation supercapacitors.

    PubMed

    Patil, Umakant; Lee, Su Chan; Kulkarni, Sachin; Sohn, Ji Soo; Nam, Min Sik; Han, Suhyun; Jun, Seong Chan

    2015-04-01

    Nowadays, advancement in performance of proficient multifarious electrode materials lies conclusively at the core of research concerning energy storage devices. To accomplish superior capacitance performance the requirements of high capacity, better cyclic stability and good rate capability can be expected from integration of electrochemical double layer capacitor based carbonaceous materials (high power density) and pseudocapacitive based metal hydroxides/oxides or conducting polymers (high energy density). The envisioned three dimensional (3D) graphene foams are predominantly advantageous to extend potential applicability by offering a large active surface area and a highly conductive continuous porous network for fast charge transfer with decoration of nanosized pseudocapacitive materials. In this article, we review the latest methodologies and performance evaluation for several 3D graphene based metal oxides/hydroxides and conducting polymer electrodes with improved electrochemical properties for next-generation supercapacitors. The most recent research advancements of our and other groups in the field of 3D graphene based electrode materials for supercapacitors are discussed. To assess the studied materials fully, a careful interpretation and rigorous scrutiny of their electrochemical characteristics is essential. Auspiciously, both nano-structuration as well as confinement of metal hydroxides/oxides and conducting polymers onto a conducting porous 3D graphene matrix play a great role in improving the performance of electrodes mainly due to: (i) active material access over large surface area with fast charge transportation; (ii) synergetic effect of electric double layer and pseudocapacitive based charge storing. PMID:25807279

  3. Thermophysical Analysis of High Modulus Composite Materials for Space Vehicles

    NASA Astrophysics Data System (ADS)

    Lee, Ho-Sung

    2009-01-01

    High modulus composite materials are used extensively in aerospace vehicles mainly for the purpose of increasing strength and reducing weight. However, thermal properties have become essential design information with the use of composite materials in the thermal design of spacecraft and spacecraft electronics packages. This is because the localized heat from closely packed devices can lead to functional failure of the aerospace system unless the heat is dissipated. In this study, thermal responses of high modulus advanced materials are considered for aerospace thermal design. The advanced composite material is composed of a continuous high modulus pitch based fiber and epoxy resin. In order to compare this advanced composite material with conventional aerospace composite materials, the thermophysical analysis of both materials was performed. The results include thermal conductivity measurements of composite materials and various thermal analytical techniques with DSC, TGA, TMA and DMA.

  4. Nonequilibrium molecular dynamics for bulk materials and nanostructures (to appear in J. Mech. Phys. Solids., doi: 10.1016/j.jmps.2009.10.008) Kaushik Dayal and Richard D. James Nonequilibrium molecular dynamics for bulk materials and

    E-print Network

    McGaughey, Alan

    to the Principle of Material Frame Indifference, a cornerstone of nonlinear continuum mechanics. The methodNonequilibrium molecular dynamics for bulk materials and nanostructures (to appear in J. Mech. Phys dynamics for bulk materials and nanostructures Kaushik Dayal Department of Civil and Environmental

  5. Sonoelectrochemical Approach Towards Nanostructures

    NASA Astrophysics Data System (ADS)

    Burda, Clemens; Qiu, Xiaofeng

    2006-03-01

    We will report on the sonoelectrochemical synthesis of nanostructured semiconductor materials. The talk will focus on the control of the nanostructure size, shape, and composition using sonolectrochemistry as a versatile synthesis tool. The synthesis of targeted nanostructures requires thorough control of the redox chemistry during the growth process. The composition of the product can be controlled by changing the initial metal-ligand concentration. Futhermore, the properties of the novel materials will be discussed. Powder X-ray diffraction of the products confirmed the compositional change in the nanomaterials. Control of the involved sonoelectrochemistry also allows for the formation of highly monodispersed 1-D Nanorods. Qiu, Xiaofeng; Lou, Yongbing; Samia, Anna C. S.; Devadoss, Anando; Burgess, James D.; Dayal, Smita; Burda, Clemens. PbTe nanorods by sonoelectrochemistry. Angewandte Chemie, International Edition (2005), 44(36), 5855-5857. Qiu, Xiaofeng; Burda, Clemens; Fu, Ruiling; Pu, Lin; Chen, Hongyuan; Zhu, Junjie. Heterostructured Bi2Se3 Nanowires with Periodic Phase Boundaries. Journal of the American Chemical Society (2004), 126(50), 16276-16277.

  6. Polymer and Composite Materials Used in Hydrogen Service

    E-print Network

    ), Fuel Cell Technologies Office, to discuss issues associated with polymer and composite materials used1 Polymer and Composite Materials Used in Hydrogen Service MEETING PROCEEDINGS Polymer This report1 describes the results from an information-sharing meeting on the use of polymer and composite

  7. Structural Health Monitoring of Smart Composite Material by Acoustic Emission

    E-print Network

    Paris-Sud XI, Université de

    Structural Health Monitoring of Smart Composite Material by Acoustic Emission S. Masmoudia , A. El fabricated in E-glass fibre/epoxy with a unidirectional play laminate. The composite specimens with sensors composite structures gives the opportunity to develop smart materials for health monitoring systems

  8. The production and application of metal matrix composite materials

    Microsoft Academic Search

    J. W. Kaczmar; K. Pietrzak; W. W?osi?ski

    2000-01-01

    The production methods and properties of metal matrix composite materials reinforced with dispersion particles, platelets, non-continuous (short) and continuous (long) fibres are discussed in this paper. The most widely applied methods for the production of composite materials and composite parts are based on casting techniques such as the squeeze casting of porous ceramic preforms with liquid metal alloys and powder

  9. Optimisation of a multiphase intermetallic metal metal composite material

    E-print Network

    Cambridge, University of

    Optimisation of a multiphase intermetallic metal ± metal composite material J. D. Robson, N to as metal ± metal composites (MeMeCs). In these materials the strong but brittle b and b9 phases act. Duvauchelle, A. Lugan, J. Street, and H. K. D. H. Bhadeshia Metal ± metal composites (MeMeCs) manufactured

  10. Thermal expansion of two-phase texturized composite materials

    Microsoft Academic Search

    R. F. Kozlova; V. B. Rabkin

    1972-01-01

    Theoretical and experimental studies were made of the effects of temperature and composition on the thermal expansion of deformed (texturized) Mo-Cu two-phase composite materials, whose component phases differ markedly in their properties. The anisotropy of thermal expansion of such composite materials was investigated, and it was established that their volume expansion shows very little variation with deformation. It is demonstrated

  11. Review on advanced composite materials boring mechanism and tools

    Microsoft Academic Search

    Runping Shi; Chengyong Wang

    2010-01-01

    With the rapid development of aviation and aerospace manufacturing technology, advanced composite materials represented by carbon fibre reinforced plastics (CFRP) and super hybrid composites (fibre\\/metal plates) are more and more widely applied. The fibres are mainly carbon fibre, boron fibre, Aramid fiber and Sic fibre. The matrixes are resin matrix, metal matrix and ceramic matrix. Advanced composite materials have higher

  12. Viscoelastic models for polymeric composite materials

    SciTech Connect

    Bardenhagen, S.G.; Harstad, E.N. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Foster, J.C. Jr. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)]|[Wright Laboratory, Armament Directorate, Eglin AFB, Florida 32542 (United States); Maudlin, P.J. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1996-05-01

    An improved model of the mechanical properties of the explosive contained in conventional munitions is needed to accurately simulate performance and accident scenarios in weapons storage facilities. A specific class of explosives can be idealized as a mixture of two components: energetic crystals randomly suspended in a polymeric matrix (binder). Strength characteristics of each component material are important in the macroscopic behavior of the composite (explosive). Of interest here is the determination of an appropriate constitutive law for a polyurethane binder material. A Taylor Cylinder impact test, and uniaxial stress tension and compression tests at various strain rates, have been performed on the polyurethane. Evident from time resolved Taylor Cylinder profiles, the material undergoes very large strains ({gt}100{percent}) and yet recovers its initial configuration. A viscoelastic constitutive law is proposed for the polyurethane and was implemented in the finite element, explicit, continuum mechanics code EPIC. The Taylor Cylinder impact experiment was simulated and the results compared with experiment. Modeling improvements are discussed. {copyright} {ital 1996 American Institute of Physics.}

  13. Method for preparing polyolefin composites containing a phase change material

    DOEpatents

    Salyer, Ival O. (Dayton, OH)

    1990-01-01

    A composite useful in thermal energy storage, said composite being formed of a polyolefin matrix having a phase change material such as a crystalline alkyl hydrocarbon incorporated therein. The composite is useful in forming pellets, sheets or fibers having thermal energy storage characteristics; methods for forming the composite are also disclosed.

  14. Multifunctional iron-based metal oxide nanostructured materials: Synthesis, characterization, and properties

    Microsoft Academic Search

    Tae-Jin Park

    2007-01-01

    Iron-based metal oxides, such as iron oxides, iron-containing perovskites, and iron-containing perovskite composites or solid solutions, are promising materials for the design and synthesis of technologically important multifunctional materials. They are noteworthy for their unique and diverse properties including electronic, magnetic, and elastic ones. Stimulated by interest in the bulk properties of these materials as well as scientific potential and

  15. In-situ TEM - a tool for quantitative observations of deformation behavior in thin films and nano-structured materials

    SciTech Connect

    Stach, E.A.

    2001-09-04

    This paper highlights future developments in the field of in-situ transmission electron microscopy, as applied specifically to the issues of deformation in thin films and nanostructured materials. Emphasis is place on the forthcoming technical advances that will aid in extraction of improved quantitative experimental data using this technique.

  16. Method of preparing corrosion resistant composite materials

    DOEpatents

    Kaun, Thomas D. (320 Willow St., New Lenox, IL 60451)

    1993-01-01

    Method of manufacture of ceramic materials which require stability in severely-corrosive environment having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These surfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  17. Hybrid nanocolloids with programmed three-dimensional shape and material composition.

    PubMed

    Mark, Andrew G; Gibbs, John G; Lee, Tung-Chun; Fischer, Peer

    2013-09-01

    Tuning the optical, electromagnetic and mechanical properties of a material requires simultaneous control over its composition and shape. This is particularly challenging for complex structures at the nanoscale because surface-energy minimization generally causes small structures to be highly symmetric. Here we combine low-temperature shadow deposition with nanoscale patterning to realize nanocolloids with anisotropic three-dimensional shapes, feature sizes down to 20 nm and a wide choice of materials. We demonstrate the versatility of the fabrication scheme by growing three-dimensional hybrid nanostructures that contain several functional materials with the lowest possible symmetry, and by fabricating hundreds of billions of plasmonic nanohelices, which we use as chiral metafluids with record circular dichroism and tunable chiroptical properties. PMID:23793159

  18. Fiber optics in composite materials: materials with nerves of glass

    NASA Astrophysics Data System (ADS)

    Measures, Raymond M.

    1990-08-01

    A Fiber Optic BasedSmart Structure wiipossess a structurally integrated optical microsensor system for determining its state. This built-in sensor system should, in real-time, be able to: evaluate the strain or deformation of a structure, monitor if its vibrating or subject to excessive loads, check its temperature and warn of the appearance of any hot spots. In addition a Smart Structure should maintain a vigilant survelliance over its structural integrity. The successful development of Smart StructureTechnolgy could lead to: aircraft that are safer, lighter, more efficient, easier to maintain and to service; pipelines, pressure vessels and storage tanks that constantly monitor their structuralintegrity and immediately issue an alert ifany problem is detected; space platforms that check forpressure leaks, unwanted vibration, excess thermal buildup, and deviation from some preassigned shape.This technology is particularly appropriate for composite materials where internal damage generated by: impacts, manufacturing flaws, excessive loading or fatigue could be detected and assessed. In service monitoring of structural loads, especially in regions like wing roots of aircraft, could be ofconsiderable benefit in helping to avoid structural overdesign and reduce weight. Structurally imbedded optical fibers sensors might also serve to monitor the cure state of composite thermosets during their fabrication and thereby contribute to improved quality control of these products.

  19. In-situ nanostructure generation and evolution within a bulk thermoelectric material to reduce lattice thermal conductivity

    SciTech Connect

    Girard, Steven; He, Jiaqing; Li, Chang-Peng; Moses, Steven; Wang, Guoyu Y; Uher, Ctirad; Dravid, Vinayak; Kanatzidis, Mercouri G.

    2010-01-01

    We show experimentally the direct reduction in lattice thermal conductivity as a result of in situ nanostructure generation within a thermoelectric material. Solid solution alloys of the high-performance thermoelectric PbTe?PbS 8% can be synthesized through rapid cooling and subsequent high-temperature activation that induces a spontaneous nucleation and growth of PbS nanocrystals. The emergence of coherent PbS nanostructures reduces the lattice thermal conductivity from ?1 to ?0.4 W/mK between 400 and 500 K.

  20. Controlling the synthetic pathways of TiO2-derived nanostructured materials.

    PubMed

    Lim, San Hua; Ji, Wei; Lin, Jianyi

    2007-09-01

    A comprehensive study of the hydrothermal synthesis of TiO2-derived nanostructured materials, including layered protonic trititanate (H2Ti3O7), metal-ion exchangeable titanate (Na(x)H(2-x)Ti3O7), TiO2(B) and anatase nanotubes and TiO2-anatase nanowires, was conducted. Nanoscaled tubular structures were found to be already present in the samples derived from prolonged hydrothermal process of bulk anatase TiO2 and could be converted to various types of nanotubes, nanowires or nanorodes by post-synthesis treatments. 0.1 M HCI acid wash and air annealing were the two key parameters to select the types of nanotubes/nanowires as the final products. XRD, Raman, TG, and XPS core level and valence band studies were carried out to elucidate our proposed synthetic pathways. PMID:18019163

  1. Ternary eutectic growth of nanostructured thermoelectric Ag-Pb-Te materials

    SciTech Connect

    Wu, Hsin-jay; Chen, Sinn-wen [Department of Chemical Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Rd., Hsin-Chu 300, Taiwan (China); Foo, Wei-jian [Engineering Science Programme, National University of Singapore, Blk EA, 06-10, 9 Engineering Drive, Singapore 117576 (Singapore); Jeffrey Snyder, G. [Materials Science, California Institute of Technology, 1200 California Blvd., Pasadena, California 91125 (United States)

    2012-07-09

    Nanostructured Ag-Pb-Te thermoelectric materials were fabricated by unidirectionally solidifying the ternary Ag-Pb-Te eutectic and near-eutectic alloys using the Bridgeman method. Specially, the Bridgman-grown eutectic alloy exhibited a partially aligned lamellar microstructure, which consisted of Ag{sub 5}Te{sub 3} and Te phases, with additional 200-600 nm size particles of PbTe. The self-assembled interfaces altered the thermal and electronic transport properties in the bulk Ag-Pb-Te eutectic alloy. Presumably due to phonon scattering from the nanoscale microstructure, a low thermal conductivity ({kappa} = 0.3 W/mK) was achieved of the eutectic alloy, leading to a zT peak of 0.41 at 400 K.

  2. Developing polymer composite materials: carbon nanotubes or graphene?

    PubMed

    Sun, Xuemei; Sun, Hao; Li, Houpu; Peng, Huisheng

    2013-10-01

    The formation of composite materials represents an efficient route to improve the performances of polymers and expand their application scopes. Due to the unique structure and remarkable mechanical, electrical, thermal, optical and catalytic properties, carbon nanotube and graphene have been mostly studied as a second phase to produce high performance polymer composites. Although carbon nanotube and graphene share some advantages in both structure and property, they are also different in many aspects including synthesis of composite material, control in composite structure and interaction with polymer molecule. The resulting composite materials are distinguished in property to meet different applications. This review article mainly describes the preparation, structure, property and application of the two families of composite materials with an emphasis on the difference between them. Some general and effective strategies are summarized for the development of polymer composite materials based on carbon nanotube and graphene. PMID:23813859

  3. Tungsten-based composite materials for fusion reactor shields

    Microsoft Academic Search

    E. Greenspan; Y. Karni

    1985-01-01

    Composite tungsten-based materials were recently proposed for the heavy constituent of compact fusion reactor shields. These composite materials will enable the incorporation of tungsten - the most efficient nonfissionable inelastic scattering (as well as good neutron absorbing and very good photon attenuating) material - in the shield in a relatively cheap way and without introducing voids (so as to enable

  4. Composite materials with metallic matrix and ceramic porous filler

    Microsoft Academic Search

    V. I. Bakarinova; V. K. Portnoi

    1995-01-01

    Composite materials with a reduced density reinforced with hollow corundum particles can be of interest as damping and abrasive materials for decreasing the mass of a structure. Methods for mixing powders and their hot pressing are suggested in order to produce such composite materials without fracture of the brittle hollow particles of the filler.

  5. High-porosity powder-fiber composite materials

    Microsoft Academic Search

    A. G. Kostornov; N. E. Fedorova; L. I. Chernyshev

    1983-01-01

    The feasibility is demonstrated of substantially reducing volume changes during the sintering of high-porosity materials by the addition of fibers to a powder mixture. The mechanism of sintering of powder-fiber composites containing more than 25% of fibers is similar to the mechanism of sintering of pure fiber materials. The mechanical properties of permeable composite materials are determined by the fiber

  6. Molecular level assessment of thermal transport and thermoelectricity in materials: From bulk alloys to nanostructures

    NASA Astrophysics Data System (ADS)

    Kinaci, Alper

    The ability to manipulate material response to dynamical processes depends on the extent of understanding of transport properties and their variation with chemical and structural features in materials. In this perspective, current work focuses on the thermal and electronic transport behavior of technologically important bulk and nanomaterials. Strontium titanate is a potential thermoelectric material due to its large Seebeck coefficient. Here, first principles electronic band structure and Boltzmann transport calculations are employed in studying the thermoelectric properties of this material in doped and deformed states. The calculations verified that excessive carrier concentrations are needed for this material to be used in thermoelectric applications. Carbon- and boron nitride-based nanomaterials also offer new opportunities in many applications from thermoelectrics to fast heat removers. For these materials, molecular dynamics calculations are used to evaluate lattice thermal transport. To do this, first, an energy moment term is reformulated for periodic boundary conditions and tested to calculate thermal conductivity from Einstein relation in various systems. The influences of the structural details (size, dimensionality) and defects (vacancies, Stone-Wales defects, edge roughness, isotopic disorder) on the thermal conductivity of C and BN nanostructures are explored. It is observed that single vacancies scatter phonons stronger than other type of defects due to unsatisfied bonds in their structure. In pristine states, BN nanostructures have 4-6 times lower thermal conductivity compared to C counterparts. The reason of this observation is investigated on the basis of phonon group velocities, life times and heat capacities. The calculations show that both phonon group velocities and life times are smaller in BN systems. Quantum corrections are also discussed for these classical simulations. The chemical and structural diversity that could be attained by mixing hexagonal boron nitride and graphene provide further avenues for tuning thermal and electronic properties. In this work, the thermal conductivity of hybrid graphene/hexagonal-BN structures: stripe superlattices and BN (graphene) dots embedded in graphene (BN) are studied. The largest reduction in thermal conductivity is observed at 50% chemical mixture in dot superlattices. The dot radius appears to have little effect on the magnitude of reduction around large concentrations while smaller dots are more influential at dilute systems.

  7. Computational study of energy filtering effects in one-dimensional composite nano-structures

    NASA Astrophysics Data System (ADS)

    Kim, Raseong; Lundstrom, Mark S.

    2012-01-01

    Possibilities to improve the Seebeck coefficient S versus electrical conductance G trade-off of diffusive composite nano-structures are explored using an electro-thermal simulation framework based on the non-equilibrium Green's function method for quantum electron transport and the lattice heat diffusion equation. We examine the role of the grain size d, potential barrier height ?B, grain doping, and the lattice thermal conductivity ?L using a one-dimensional model structure. For a uniform ?L, simulation results show that the power factor of a composite structure may be improved over bulk with the optimum ?B being about kBT, where kB and T are the Boltzmann constant and the temperature, respectively. An optimum ?B occurs because the current flow near the Fermi level is not obstructed too much while S still improves due to barriers. The optimum grain size dopt is significantly longer than the momentum relaxation length ?p so that G is not seriously degraded due to the barriers, and dopt is comparable to or somewhat larger than the energy relaxation length ?E so that the carrier energy is not fully relaxed within the grain and |S| remains high. Simulation results also show that if ?L in the barrier region is smaller than in the grain, S and power factor are further improved. In such cases, the optimum ?B and dopt increase, and the power factor may improve even for ?B (d) significantly higher (longer) than kBT (?E). We find that the results from this quantum mechanical approach are readily understood using a simple, semi-classical model.

  8. Chemically modified and nanostructured porous silicon as a drug delivery material and device

    NASA Astrophysics Data System (ADS)

    Anglin, Emily Jessica

    This thesis describes the fabrication, chemical modification, drug release, and toxicity studies of nanostructured porous silicon for the purposes of developing a smart drug delivery device. The first chapter is an introductory chapter, presenting the chemical and physical properties of porous silicon, the concepts and issues of current drug delivery devices and materials, and how porous silicon can address the issues regarding localized and controlled drug therapies. The second chapter discusses chemical modifications of nanostructured porous Si for stabilizing the material in biologically relevant media while providing an extended release of a therapeutic in vitro. This chapter also demonstrates the utility of the porous silicon optical signatures for effectively monitoring drug release from the system and its applications for development of a self-reporting drug delivery device. In chapter three, the concept of providing a triggered release of a therapeutic from porous silicon microparticles through initiation by an external stimulus is demonstrated. The microparticles are chemically modified, and the release is enhanced by a short application of ultrasound to the particulate system. The effect of ultrasound on the drug release and particle size is discussed. Chapter four presents a new method for sustaining the release of a monoclonal antibody from the porous matrix of porous SiO2. The therapeutic is incorporated into the films through electrostatic adsorption and a slow release is observed in vitro. A new method of quantifying the extent of drug loading is monitored with interferometry. The last chapter of the thesis provides a basic in vivo toxicity study of various porous Si microparticles for intraocular applications. Three types of porous Si particles are fabricated and studied in a rabbit eye model. The toxicity studies were conducted by collaborators at the Shiley Eye Center, La Jolla, CA. This work, demonstrates the feasibility of developing a self-reporting, extended release drug delivery system using porous Si microparticles for intraocular applications.

  9. Natural frequency and damping behavior of composite materials

    E-print Network

    Duggan, Matthew Brace

    1990-01-01

    . The goal is to be able to control and predict the vibration and damping of a composite structure in the design phase. 2. REVIEW OF LITERATURE Many models of composite plates have been proposed, but the effects of the stacking sequence, material system... to gain a data base for static and dynamic response of composite components. This project focuses on the vibration and damping characterization of composites in the presence of damage. The effects of selection of material system, size, stacking...

  10. Attenuation of shock waves propagating through nano-structured porous materials

    NASA Astrophysics Data System (ADS)

    Al-Qananwah, Ahmad K.; Koplik, Joel; Andreopoulos, Yiannis

    2013-07-01

    Porous materials have long been known to be effective in energy absorption and shock wave attenuation. These properties make them attractive in blast mitigation strategies. Nano-structured materials have an even greater potential for blast mitigation because of their high surface-to-volume ratio, a geometric parameter which substantially attenuates shock wave propagation. A molecular dynamics approach was used to explore the effects of this remarkable property on the behavior of traveling shocks impacting on solid materials. The computational setup included a moving piston, a gas region and a target solid wall with and without a porous structure. The gas and porous solid were modeled by Lennard-Jones-like and effective atom potentials, respectively. The shock wave is resolved in space and time and its reflection from a solid wall is gradual, due to the wave's finite thickness, and entails a self-interaction as the reflected wave travels through the incoming incident wave. Cases investigated include a free standing porous structure, a porous structure attached to a wall and porous structures with graded porosity. The effects of pore shape and orientation have been also documented. The results indicate that placing a nano-porous material layer in front of the target wall reduced the stress magnitude and the energy deposited inside the solid by about 30 percent, while at the same time substantially decreasing the loading rate.

  11. Shape memory materials and hybrid composites for smart systems: Part II Shape-memory hybrid composites

    Microsoft Academic Search

    Z. G. Wei; R. Sandstrom; S. Miyazaki

    1998-01-01

    By hybridizing or incorporating shape-memory materials with other functional materials or structural materials, smart composites can be fabricated which may utilize the unique functions or properties of the individual bulk materials to achieve multiple responses and optimal properties, or, to tune their properties to adapt to environmental changes. A variety of shape-memory hybrid composites have been designed and manufactured, with

  12. Millimeter-wave imaging of composite materials

    SciTech Connect

    Gopalsami, N.; Bakhtiari, S.; Dieckman, S.L.; Raptis, A.C.; Lepper, M.J.

    1993-09-01

    This work addresses the application and evaluates the potential of mm-wave imaging in the W-band (75-110 GHz) using samples of low-loss dielectric and composite materials with artificial defects. The initial focus is on the measurement of amplitude changes in the back scattered and forward-scattered fields. The c-scan system employs a focused beam antenna to provide spatial resolution of about one wavelength. A plane-wave model is used to calculate the effective reflection (or transmission) coefficient of multilayer test sample geometry. Theoretical analysis is used to optimize the measurement frequency for higher image contrast and to interpret the experimental results. Both reflection and transmission images, based on back scattered and forward-scattered powers, were made with Plexiglas and Kevlar/epoxy samples containing artificially introduced defects such as subsurface voids and disbonds. The results clearly indicate that mm-wave imaging has high potential for non-contact interrogation of low-loss materials.

  13. Liquid crystal alignment in electro-responsive nanostructured thermosetting materials based on block copolymer dispersed liquid crystal

    NASA Astrophysics Data System (ADS)

    Tercjak, A.; Garcia, I.; Mondragon, I.

    2008-07-01

    Novel well-defined nanostructured thermosetting systems were prepared by modification of a diglicydylether of bisphenol-A epoxy resin (DGEBA) with 10 or 15 wt% amphiphilic poly(styrene-b-ethylene oxide) block copolymer (PSEO) and 30 or 40 wt% low molecular weight liquid crystal 4'-(hexyl)-4-biphenyl-carbonitrile (HBC) using m-xylylenediamine (MXDA) as a curing agent. The competition between well-defined nanostructured materials and the ability for alignment of the liquid crystal phase in the materials obtained has been studied by atomic and electrostatic force microscopy, AFM and EFM, respectively. Based on our knowledge, this is the first time that addition of an adequate amount (10 wt%) of a block copolymer to 40 wt% HBC-(DGEBA/MXDA) leads to a well-organized nanostructured thermosetting system (between a hexagonal and worm-like ordered structure), which is also electro-responsive with high rate contrast. This behavior was confirmed using electrostatic force microscopy (EFM), by means of the response of the HBC liquid crystal phase to the voltage applied to the EFM tip. In contrast, though materials containing 15 wt% PSEO and 30 wt% HBC also form a well-defined nanostructured thermosetting system, they do not show such a high contrast between the uncharged and charged surface.

  14. Strain-driven oxygen deficiency in self-assembled, nanostructured, composite oxide films.

    PubMed

    Cantoni, Claudia; Gao, Yanfei; Wee, Sung Hun; Specht, Eliot D; Gazquez, Jaume; Meng, Jianyong; Pennycook, Stephen J; Goyal, Amit

    2011-06-28

    Oxide self-assembly is a promising bottom-up approach for fabricating new composite materials at the nanometer length scale. Tailoring the properties of such systems for a wide range of electronic applications depends on the fundamental understanding of the interfaces between the constituent phases. We show that the nanoscale strain modulation in self-assembled systems made of high-T(c) superconducting films containing nanocolumns of BaZrO(3) strongly affects the oxygen composition of the superconductor. Our findings explain the observed reduction of the superconducting critical temperature. PMID:21604819

  15. Possibility of obtaining monolithic composite materials based on niobium carbide

    Microsoft Academic Search

    V. V. Ploshkin; I. Yu. Ul'yanina; V. P. Filonenko

    1984-01-01

    1.Specimens of composite material based on niobium carbide obtained by hydrostatic pressing had minimum porosity compared with specimens obtained by the normal powder metallurgy method.2.Basic phases of the composite material consisting of copper and niobium carbide are uniformly distributed throughout the specimen cross section and they do not react with each other under any conditions.3.The composite material obtained exhibits sufficient

  16. New Micro Structural Design Concept for Polycrystalline Composite Materials

    Microsoft Academic Search

    A. N. RYBJANETS; A. V. NASEDKIN; A. V. TURIK

    2004-01-01

    A new concept of microstructural designing of polymer-free polycrystalline composite materials is offered. The concept based on controllable substitution during composite formation of separate crystallites making a polycrystal by pores, crystallites with other composition and\\/or structure or amorphous substances with preliminary FEM modeling of polycrystalline composite properties. A line of precursor small-scale production technologies and polycrystalline composites with unique and

  17. Co-evaporation of transition metal salt and SiO powder toward copper(or nickel)/silicon-contained composite nanostructures

    SciTech Connect

    Zhou, Gang [Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Zhongguancundonglu 29, Haidianqu, Beijing 100190 (China) [Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Zhongguancundonglu 29, Haidianqu, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Cao, Yang [Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Zhongguancundonglu 29, Haidianqu, Beijing 100190 (China)] [Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Zhongguancundonglu 29, Haidianqu, Beijing 100190 (China); He, Junhui, E-mail: jhhe@mail.ipc.ac.cn [Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Zhongguancundonglu 29, Haidianqu, Beijing 100190 (China)] [Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Zhongguancundonglu 29, Haidianqu, Beijing 100190 (China)

    2013-01-15

    Graphical abstract: Copper(or nickel)/silicon-contained composite nanostructures were successfully synthesized by co-evaporating SiO powder and corresponding transition metal salts (nickel formate and copper sulfate). Display Omitted Highlights: ? Novel nanostructures were synthesized by co-evaporating SiO and metal salts. ? A pre-sintering process was used in the synthesis of copper/silicon nanocomposites. ? A Ni{sub 31}Si{sub 12}/Si/SiO{sub 2} nanocomposite was obtained. ? Peapod-like copper/silicon-contained nanocomposites were obtained. ? On the basis of experimental results, the formation mechanism was discussed. -- Abstract: We demonstrate that several novel copper(or nickel)/silicon-contained composite nanostructures were successfully synthesized by co-evaporating SiO powder and corresponding transition metal salts (transition metal organic salt and transition metal inorganic salt), including nickel formate, cobalt acetate, and copper sulfate. The morphologies, compositions, and crystal structures of products were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The results indicate that the morphology and composition of formed copper(or nickel)/silicon-contained composite nanostructures are dramatically influenced by the distance between SiO powder and transition metal salts, or by the pre-sintering temperature of the reactants. The possible formation mechanisms of these composite nanostructures were discussed on the basis of experimental observations.

  18. Self-propagating high-temperature synthesis of promising ceramic materials for deposition technologies of functional nanostructured coatings

    Microsoft Academic Search

    E. A. Levashov; V. V. Kurbatkina; E. I. Patsera; Yu. S. Pogozhev; S. I. Rupasov; A. S. Rogachev

    2010-01-01

    Taking into account the demand for composite targets or precursors for ion-plasma technologies for the deposition of functional\\u000a nanostructured coatings, this work is a review of recently obtained and previously unpublished results of synthesis in the\\u000a combustion mode of a series of chemical classes of systems differing in regards to the mechanisms of combustion and structure\\u000a formation. The experimental results

  19. POLYDIMETHYLSILOXANE-BASED SELF-HEALING COMPOSITE AND COATING MATERIALS

    E-print Network

    Braun, Paul

    POLYDIMETHYLSILOXANE-BASED SELF-HEALING COMPOSITE AND COATING MATERIALS BY SOO HYOUN CHO B-healing polymers by introducing tin catalyzed polycondensation of hydroxyl end- functionalized polydimethylsiloxane

  20. Design and assembly of nanostructured complex metal oxide materials for the construction of batteries and thermoelectric devices

    NASA Astrophysics Data System (ADS)

    Yadav, Gautam Ganapati

    Thermoelectric devices and lithium-ion batteries are among the fastest growing energy technologies. Thermoelectric devices generate energy from waste heat, whereas lithium-ion batteries store energy for use in commercial applications. Two different topics are bound with a common thread in this thesis - nanotechnology! In fact, nanostructuring is a more preferred term for the approach I have taken herein. Another commonality between these two topics is the material system I have used to prove my hypotheses - complex metal oxides. Complex metal oxides can be used for both energy generation and storage as they are stable at high temperatures, are benign and inexpensive, and are chemically stable. . Nevertheless, complex metal oxide-based materials have drawbacks when they are used in thermoelectric devices. Since they have high thermal conductivities and low power factors, they have lower thermoelectric figures of merit (ZT). This affects their performance as thermoelectric materials. Nanostructuring can solve this critical problem as thermal conductivity, electrical conductivity and Seebeck coefficient become quasi-independent of each other under these conditions. However, oxide-based materials have proven to be greatly recalcitrant to forming nanostructures when traditional synthetic methods such as solid-state reactions have been employed. Solid-state reactions usually proceed at extremely high temperatures that are not particularly conducive to forming nanostructures. The first part of this thesis presents novel solution-based synthetic methods that were developed in order to produce novel nanostructured complex metal oxides. Typical structures include nanowires. The second part of this thesis extends this methodology to study the effect of nanostructuring on the thermal conductivity of strontium titanate (SrTiO3), a promising high temperature thermoelectric material. Ultrathin nanowires of SrTiO3 were synthesized using a novel hydrothermal reaction. These ultrathin nanowires were compressed into a `nanostructured' bulk pellet through spark plasma sintering. The thermal conductivity measured on the nanostructured bulk pellet showed a drastic decrease compared to bulk SrTiO3. Through theoretical modeling it was realized that drastic decrease in thermal conductivity was due to scattering of phonons, which contribute to the lattice thermal conductivity, at the interface of the nanowires. Another aspect of the thermoelectric research presented herein includes the development of a new phase of misfit layered oxide, calcium cobalt oxide (Ca9Co12O28), for high temperature applications. This phase had hardly been researched in literature because of its high thermal conductivity, thus limiting its use in thermoelectric devices. Through a unique single source precursor-based technique, porous nanowire structures of Ca9Co12O28 were prepared at much lower temperatures than conventional solid-state techniques. Significantly improved ZT were observed in our nanowire system up to 700K due to reduced thermal conductivity and enhanced Seebeck coefficient. The synthetic approach was also applied to prepare different nanostructures (porous nanowires and nanoparticles) of lithium cobalt oxide (LiCoO2) by tuning individual reaction parameters. The importance of reaction temperature and the role of nanostructures on the final electrochemical performance of LiCoO2 was also deduced. Saliently, the nanostructured electrodes so prepared can withstand high cycling rates and achieve capacities that are close to the theoretical capacity of LiCoO2 at 0.1C.

  1. High thermoelectric performance of nonequilibrium synthesized CeFe4Sb12 composite with multi-scaled nanostructures

    NASA Astrophysics Data System (ADS)

    Tan, Gangjian; Zheng, Yun; Tang, Xinfeng

    2013-10-01

    High thermoelectric performance p-type CeFe4Sb12 composite with rich nanostructures are rapidly prepared by a melt spinning coupled with spark plasma sintering technique. Melt spinning markedly refines the matrix grain size (200-500 nm). We also find evenly distributed FeSb2 nanodots (<50 nm) inside the skutterudite grains due to the inherent structural instability of Fe-containing skutterudites. Meanwhile, by adding excessive Ce into the CeFe4Sb12 matrix, unique CeSb2 nanoinclusions (50-150 nm) are in-situ formed on the grain boundaries. The multi-scaled nanostructures scatter a broad spectrum of heat-carrying phonons, leading to a maximum thermoelectric figure of merit ZT above unity in the skutterudite nanocomposite.

  2. Development of Nano-structured Electrode Materials for High Performance Energy Storage System

    NASA Astrophysics Data System (ADS)

    Huang, Zhendong

    Systematic studies have been done to develop a low cost, environmental-friendly facile fabrication process for the preparation of high performance nanostructured electrode materials and to fully understand the influence factors on the electrochemical performance in the application of lithium ion batteries (LIBs) or supercapacitors. For LIBs, LiNi1/3Co1/3Mn1/3O2 (NCM) with a 1D porous structure has been developed as cathode material. The tube-like 1D structure consists of inter-linked, multi-facet nanoparticles of approximately 100-500nm in diameter. The microscopically porous structure originates from the honeycomb-shaped precursor foaming gel, which serves as self-template during the stepwise calcination process. The 1D NCM presents specific capacities of 153, 140, 130 and 118mAh·g-1 at current densities of 0.1C, 0.5C, 1C and 2C, respectively. Subsequently, a novel stepwise crystallization process consisting of a higher crystallization temperature and longer period for grain growth is employed to prepare single crystal NCM nanoparticles. The modified sol-gel process followed by optimized crystallization process results in significant improvements in chemical and physical characteristics of the NCM particles. They include a fully-developed single crystal NCM with uniform composition and a porous NCM architecture with a reduced degree of fusion and a large specific surface area. The NCM cathode material with these structural modifications in turn presents significantly enhanced specific capacities of 173.9, 166.9, 158.3 and 142.3mAh·g -1 at 0.1C, 0.5C, 1C and 2C, respectively. Carbon nanotube (CNT) is used to improve the relative low power capability and poor cyclic stability of NCM caused by its poor electrical conductivity. The NCM/CNT nanocomposites cathodes are prepared through simply mixing of the two component materials followed by a thermal treatment. The CNTs were functionalized to obtain uniformly-dispersed MWCNTs in the NCM matrix. The electrochemical tests found reduced inner electron resistance and improved rate capability of the nanocomposite cathodes compared to the neat NCM, which were attributed to the 3D spatial conductive network formed by MWCNTs and Super p carbon black in the nanocomposites. The capacity retention ratios after 100 cycles of Li/NCM-CNTs cell were about 81%, much higher than that of Li/NCM cell (˜72%). As for supercapacitor, the annealed GO/CNT films or papers the binder-free electrodes are prepared and use for high performance supercapacitors. The amphiphilic nature of graphene oxide (GO) sheets allows adsorption of CNTs onto their surface in water, capable of forming highly stable dispersion. Thus, the GO/CNT hybrid films or papers are self-assembled via simple casting or vacuum filtration of aqueous dispersion. The hybrid thin film electrode with a moderate CNT content, typically 12.5wt%, give rise to remarkable electrochemical performance with extremely high specific capacitances of 428 and 145 F·g -1 at current densities of 0.5 and 100 A·g-1, respectively, as well as a remarkable retention rate 98% of the initial value after 10,000 charge/discharge cycles. The same as film type electrode, the rGO/CNT sandwich papers gives rise to an excellent specific capacitance of 151 F·g-1 at a current density of 0.5 A·g -1, as well as a remarkable retention ratio of 86 % of the initial value after 6,000 charge/discharge cycles at 5 A·g-1. These improvements arise from the synergistic effects of the increased electronic conductivity and effective surface area associated with large electrochemical active sites. The synergistic effects arising from i) the enlarged surface area of electrodes due to the intercalation of CNTs between the stacked GO sheets with associated large electrochemical active sites and ii) the improved conductivity through the formation of 3D network aided by CNTs, are mainly responsible for these findings. The effects of reduction process are also studied on the supercapacitive behavior of electrodes made from flexible graphene oxide (GO) papers. It is found that the s

  3. Nanostructured materials and their role as heterogeneous catalysts in the conversion of biomass to biofuels

    NASA Astrophysics Data System (ADS)

    Cadigan, Chris

    Prior to the discovery of inexpensive and readily available fossil fuels, the world relied heavily on biomass to provide its energy needs. Due to a worldwide growth in demand for fossil fuels coupled with the shrinkage of petroleum resources, and mounting economic, political, and environmental concerns, it has become more pressing to develop sustainable fuels and chemicals from biomass. The present dissertation studies multiple nanostructured catalysts investigated in various processes related to gasification of biomass into synthesis gas, and further upgrading to biofuels and value added chemicals. These reactions include: syngas conditioning, alcohol synthesis from carbon monoxide hydrogenation, and steam reforming ethanol to form higher hydrocarbons. Nanomaterials were synthesized, characterized, studied in given reactions, and then further characterized post-reaction. Overall goals were aimed at determining catalytic activities towards desired products and determining which material properties were most desirable based on experimental results. Strategies to improve material design for second-generation materials are suggested based on promising reaction results coupled with pre and post reaction characterization analysis.

  4. NiO-silica based nanostructured materials obtained by microemulsion assisted sol-gel procedure

    SciTech Connect

    Mihaly, M.; Comanescu, A.F. [University POLITEHNICA Bucharest, Faculty of Applied Chemistry and Materials Science, 1 Polizu, 011061 Bucharest (Romania)] [University POLITEHNICA Bucharest, Faculty of Applied Chemistry and Materials Science, 1 Polizu, 011061 Bucharest (Romania); Rogozea, A.E. [ILIE MURGULESCU Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania)] [ILIE MURGULESCU Institute of Physical Chemistry of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Vasile, E. [METAV Research and Development, 31 C.A. Rosetti, 020011 Bucharest (Romania)] [METAV Research and Development, 31 C.A. Rosetti, 020011 Bucharest (Romania); Meghea, A., E-mail: a.meghea@gmail.com [University POLITEHNICA Bucharest, Faculty of Applied Chemistry and Materials Science, 1 Polizu, 011061 Bucharest (Romania)

    2011-10-15

    Graphical abstract: TEM micrograph of NiO/SiO{sub 2} nanoparticles. Highlights: {yields} Microemulsion assisted sol-gel procedure for NiO silica nanomaterials synthesis. {yields} Controlling the size and shape of nanoparticles and avoiding their aggregation. {yields} Narrow band-gap semiconductors (energies <3 eV) absorbing VIS or near-UV light biologically and chemically inert semiconductors entrapping/coating in silica network. {yields} Low cost as the microemulsion is firstly used in water metallic cation extraction. -- Abstract: NiO-silica based materials have been synthesized by microemulsion assisted sol-gel procedure. The versatility of these soft nanotechnology techniques has been exploited in order to obtain different types of nanostructures, such as NiO nanoparticles, NiO silica coated nanoparticles and NiO embedded in silica matrix. These materials have been characterized by adequate structural and morphology techniques: DLS, HR-TEM/SAED, BET, AFM. Optical and semiconducting properties (band-gap values) of the synthesized materials have been quantified by means of VIS-NIR diffuse reflectance spectra, thus demonstrating their applicative potential in various electron transfer phenomena such as photocatalysis, electrochromic thin films, solid oxide fuel cells.

  5. ISOTOPIC COMPOSITIONS OF URANIUM REFERENCE MATERIALS

    SciTech Connect

    Jacobsen, B; Borg, L; Williams, R; Brennecka, G; Hutcheon, I

    2009-09-03

    Uranium isotopic compositions of a variety of U standard materials were measured at Lawrence Livermore National Laboratory and are reported here. Both thermal ionization mass spectrometry (TIMS) and multi-collector inductively couple plasma mass spectrometry (MC-ICPMS) were used to determine ratios of the naturally occurring isotopes of U. Establishing an internally coherent set of isotopic values for a range of U standards is essential for inter-laboratory comparison of small differences in {sup 238}U/{sup 235}U, as well as the minor isotopes of U. Differences of {approx} 1.3{per_thousand} are now being observed in {sup 238}U/{sup 235}U in natural samples, and may play an important role in understanding U geochemistry where tracing the origin of U is aided by U isotopic compositions. The {sup 238}U/{sup 235}U ratios were measured with a TRITON TIMS using a mixed {sup 233}U-{sup 236}U isotopic tracer to correct for instrument fractionation. this tracer was extremely pure and resulted in only very minor corrections on the measured {sup 238}U/{sup 235}U ratios of {approx} 0.03. The values obtained for {sup 238}U/{sup 235}U are: IRMM184 = 137.698 {+-} 0.020 (n = 15), SRM950a = 137.870 {+-} 0.018 (n = 8), and CRM112a = 137.866 {+-} 0.030 (n = 16). Uncertainties represent 2 s.d. of the population. The measured value for IRMM184 is in near-perfect agreement with the certified value of 137.697 {+-} 0.042. However, the U isotopic compositions of SRM950a and CRM112a are not certified. Minor isotopes of U were determined with a Nu Plasma HR MC-ICPMS and mass bias was corrected by sample/standard bracketing to IRMM184, using its certified {sup 238}U/{sup 235}U ratio. Thus, the isotopic compositions determined using both instruments are compatible. The values obtained for {sup 234}U/{sup 235}U are: SRM950a = (7.437 {+-} 0.043) x 10{sup -3} (n = 18), and CRM112a = (7.281 {+-} 0.050) x 10{sup -3} (n = 16), both of which are in good agreement with published values. The value for {sup 236}U/{sup 235}U in SRM950a was determined to be (8.48 {+-} 2.63) x 10{sup -6}, whereas {sup 236}U was not detected in CRM112a. They are currently obtaining the U isotopic composition of CRM129a. Preliminary results suggest that the {sup 238}U/{sup 235}U ratio is within error, but slightly lower than the certified value of 137.71.

  6. Synthesis of nanostructured MnO2, SnO2, and Co3O4: graphene composites with enhanced microwave absorption properties

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoxia; Yu, Jianhua; Dong, Hongzhou; Yu, Mingxun; Zhang, Baoqin; Wang, Wen; Dong, Lifeng

    2015-06-01

    In this work, metal oxide (MnO2, SnO2 and Co3O4)-graphene composite materials were successfully prepared via different synthesis methods. Uniform metal oxide nanoparticles were well dispersed on graphene sheets, and transmission electron microscopy characterizations showed that the average sizes of MnO2, SnO2, and Co3O4 particles were about 60, 5, and 10 nm, respectively. Reflection losses of graphene composites and pure graphene were systematically evaluated between 2 and 18 GHz, which revealed that all composites exhibited enhanced microwave absorption properties compared to pure graphene. The minimum reflection losses of MnO2-graphene, SnO2-graphene, and Co3O4-graphene composites with a thickness of 2.0 mm were -20.9, -15.28, and -7.3 dB at the frequency of 14.8, 15.94, and 9.6 GHz, respectively, whereas -4.5 dB for pure graphene. The enhanced absorption ability probably originated from the combined advantage of metal oxide particles and graphene, which proved beneficial to improve the impedance matching of permittivity and permeability. Besides, the intrinsic characteristics of MnO2, SnO2, and Co3O4 nanoparticles, the interface between nanostructured metal oxides and graphene sheets, and the multi-dielectric relaxation processes are all influence factors to improve the properties of microwave absorption.

  7. Polyoxometalate-conductive polymer composites for energy conversion, energy storage and nanostructured sensors.

    PubMed

    Herrmann, Sven; Ritchie, Chris; Streb, Carsten

    2015-04-28

    The exchange of electric charges between a chemical reaction centre and an external electrical circuit is critical for many real-life technologies. This perspective explores the "wiring" of highly redox-active molecular metal oxide anions, so-called polyoxometalates (POMs) to conductive organic polymers (CPs). The major synthetic approaches to these organic-inorganic hybrid materials are reviewed. Typical applications are highlighted, emphasizing the current bottlenecks in materials development. Utilization of the composites in the fields of energy conversion, electrochemical energy storage, sensors and nanoparticle "wiring" into conductive materials are discussed. The outlook section presents the authors' views on emerging fields of research where the combination of POMs and CPs can be expected to provide novel materials for groundbreaking new technologies. These include light-weight energy storage, high-sensitivity toxin sensors, artificial muscles, photoelectrochemical devices and components for fuel cells. PMID:25787774

  8. (Proceedings of the 5th Technical Conference on Composite Materials, American Society of Composites,

    E-print Network

    Nairn, John A.

    ]s. The first material system was supplied by DuPont and consisted of AvimidR K Polymer/IM6 graphite fiber(Proceedings of the 5th Technical Conference on Composite Materials, American Society of Composites, East Lansing, Michigan, June 11-14, 1990). Fracture Mechanics Analysis of Composite Microcracking

  9. [The emergency plastic reconstruction of the tympanic membrane defects of post-traumatic and iatrogenic etiology with the application of the nanostructured bioplastic material].

    PubMed

    Zabirov, R A; Kar'kaeva, S M; Shchetinin, V N; Akimov, A V

    2014-01-01

    The objective of the present study was to estimate the effectiveness of the application of the nanostructured bioplastic material for the plastic reconstruction of tympanic defects of post-traumatic and iatrogenic etiology. The authors report the results of the emergency plastic reconstruction of tympanic defects of post-traumatic and iatrogenic nature with the application of the nanostructured bioplastic material (giamatrix). The analysis of the results of the study prfovidd definitive evidence of the effectiveness of plastic reconstruction of tympanic defects with the application of the nanostructured bioplastic material. PMID:25588474

  10. Attaching Strain Gages to Composite Materials

    NASA Technical Reports Server (NTRS)

    Penn, B.; Clemons, J. M.; Ledbetter, F. E., III; White, W.

    1984-01-01

    Polyurethane adhesive bonds strain gages reliably to graphite/epoxy composites. Adhesive easy to apply, used over wide temperature range (ambient to cryogenic), and applied in short time. Tests on gages bonded to composite with adhesive demonstrated reliability of attachment.

  11. Some functional properties of composite material based on scrap tires

    NASA Astrophysics Data System (ADS)

    Plesuma, Renate; Malers, Laimonis

    2013-09-01

    The utilization of scrap tires still obtains a remarkable importance from the aspect of unloading the environment from non-degradable waste [1]. One of the most prospective ways for scrap tires reuse is a production of composite materials [2] This research must be considered as a continuation of previous investigations [3, 4]. It is devoted to the clarification of some functional properties, which are considered important for the view of practical applications, of the composite material. Some functional properties of the material were investigated, for instance, the compressive stress at different extent of deformation of sample (till 67% of initial thickness) (LVS EN 826) [5] and the resistance to UV radiation (modified method based on LVS EN 14836) [6]. Experiments were realized on the purposefully selected samples. The results were evaluated in the correlation with potential changes of Shore C hardness (Shore scale, ISO 7619-1, ISO 868) [7, 8]. The results showed noticeable resistance of the composite material against the mechanical influence and ultraviolet (UV) radiation. The correlation with the composition of the material, activity of binder, definite technological parameters, and the conditions supported during the production, were determined. It was estimated that selected properties and characteristics of the material are strongly dependent from the composition and technological parameters used in production of the composite material, and from the size of rubber crumb. Obtained results show possibility to attain desirable changes in the composite material properties by changing both the composition and technological parameters of examined material.

  12. Multifunctional Structural Materials for Monitoring and Vibration Plenary Talk: ASME 3-24 Multifunctional Composite Materials

    E-print Network

    Chung, Deborah D.L.

    Plenary Talk: ASME 3-24 Multifunctional Composite Materials Wednesday, 1-1:30 pmMultifunctional Structural Materials for Monitoring and Vibration Damping. November 14, 2012 Abstract Multifunctional structural materials in the form

  13. Improved Damage Resistant Composite Materials Incorporating Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Paine, Jeffrey S. N.; Rogers, Craig A.

    1996-01-01

    Metallic shape memory alloys (SMA) such as nitinol have unique shape recovery behavior and mechanical properties associated with a material phase change that have been used in a variety of sensing and actuation applications. Recent studies have shown that integrating nitinol-SMA actuators into composite materials increases the composite material's functionality. Hybrid composites of conventional graphite/epoxy or glass/epoxy and nitinol-SMA elements can perform functions in applications where monolithic composites perform inadequately. One such application is the use of hybrid composites to function both in load bearing and armor capacities. While monolithic composites with high strength-to-weight ratios function efficiently as loadbearing structures, because of their brittle nature, impact loading can cause significant catastrophic damage. Initial composite failure modes such as delamination and matrix cracking dissipate some impact energy, but when stress exceeds the composite's ultimate strength, fiber fracture and material perforation become dominant. One of the few methods that has been developed to reduce material perforation is hybridizing polymer matrix composites with tough kevlar or high modulus polyethynylene plies. The tough fibers increase the impact resistance and the stiffer and stronger graphite fibers carry the majority of the load. Similarly, by adding nitinol-SMA elements that absorb impact energy through the stress-induced martensitic phase transformation, the composites' impact perforation resistance can be greatly enhanced. The results of drop-weight and high velocity gas-gun impact testing of various composite materials will be presented. The results demonstrate that hybridizing composites with nitinol-SMA elements significantly increases perforation resistance compared to other traditional toughening elements. Inspection of the composite specimens at various stages of perforation by optical microscope illustrates the mechanisms by which perforation is initiated. Results suggest that the out-of-plane transverse shear properties of the composite and nitinol elements have a significant effect on the perforation resistance. Applications that can utilize the hybrid composites effectively will also be presented with the experimental studies.

  14. Active Nano-Structured Composite Coatings for Corrosion and Wear Protection of Steel 

    E-print Network

    Kim, Yoo Sung

    2013-08-06

    In order to obtain sustainable engineering systems, this research investigates surface and interface properties of metals and active nanostructured coatings. The goal is to develop new approaches in order to improve the ...

  15. Active Nano-Structured Composite Coatings for Corrosion and Wear Protection of Steel

    E-print Network

    Kim, Yoo Sung

    2013-08-06

    In order to obtain sustainable engineering systems, this research investigates surface and interface properties of metals and active nanostructured coatings. The goal is to develop new approaches in order to improve the corrosion resistance...

  16. Controlled synthesis of organic nanophotonic materials with specific structures and compositions.

    PubMed

    Cui, Qiu Hong; Zhao, Yong Sheng; Yao, Jiannian

    2014-10-29

    Organic nanomaterials have drawn great interest for their potential applications in high-speed miniaturized photonic integration due to their high photoluminescence quantum efficiency, structural processability, ultrafast photoresponse, and excellent property engineering. Based on the rational design on morphological and componential levels, a series of organic nanomaterials have been controllably synthesized in recent years, and their excitonic/photonic behaviors has been fine-tuned to steer the light flow for specific optical applications. This review presents a comprehensive summary of recent breakthroughs in the controlled synthesis of organic nanomaterials with specific structures and compositions, whose tunable photonic properties would provide a novel platform for multifunctional applications. First, we give a general overview of the tailored construction of novel nanostructures with various photonic properties. Then, we summarize the design and controllable synthesis of composite materials for the modulation of their functionalities. Subsequently, special emphasis is put on the fabrication of complex nanostructures towards wide applications in isolated photonic devices. We conclude with our personal viewpoints on the development directions in the novel design and controllable construction of organic nanomaterials for future applications in highly integrated photonic devices and chips. PMID:24782347

  17. Elastoplastic analysis of thermal cycling: layered materials with compositional gradients

    Microsoft Academic Search

    A. E. Giannakopoulos; S. Suresh; M. Finot; M. Olsson

    1995-01-01

    Elastopllastic analyses are presented for the cyclic thermal response in multi-layered materials which comprise layers of fixed compositions of a metal and a ceramic, and a compositionally graded interface. Analytical solutions for the characteristic temperature at which the onset of thermally induced plastic deformation occurs are derived for the layered composite. Solutions for the evolution of curvature and thermal strains,

  18. Controlled intermittent interfacial bond concept for composite materials

    NASA Technical Reports Server (NTRS)

    Marston, T. U.; Atkins, A. G.

    1975-01-01

    Concept will enhance fracture resistance of high-strength filamentary composite without degrading its tensile strength or elastic modulus. Concept provides more economical composite systems, tailored for specific applications, and composite materials with mechanical properties, such as tensile strength, fracture strain, and fracture toughness, that can be optimized.

  19. Advanced composite structures. [metal matrix composites - structural design criteria for spacecraft construction materials

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A monograph is presented which establishes structural design criteria and recommends practices to ensure the design of sound composite structures, including composite-reinforced metal structures. (It does not discuss design criteria for fiber-glass composites and such advanced composite materials as beryllium wire or sapphire whiskers in a matrix material.) Although the criteria were developed for aircraft applications, they are general enough to be applicable to space vehicles and missiles as well. The monograph covers four broad areas: (1) materials, (2) design, (3) fracture control, and (4) design verification. The materials portion deals with such subjects as material system design, material design levels, and material characterization. The design portion includes panel, shell, and joint design, applied loads, internal loads, design factors, reliability, and maintainability. Fracture control includes such items as stress concentrations, service-life philosophy, and the management plan for control of fracture-related aspects of structural design using composite materials. Design verification discusses ways to prove flightworthiness.

  20. Process for fabricating composite material having high thermal conductivity

    DOEpatents

    Colella, Nicholas J. (Livermore, CA); Davidson, Howard L. (San Carlos, CA); Kerns, John A. (Livermore, CA); Makowiecki, Daniel M. (Livermore, CA)

    2001-01-01

    A process for fabricating a composite material such as that having high thermal conductivity and having specific application as a heat sink or heat spreader for high density integrated circuits. The composite material produced by this process has a thermal conductivity between that of diamond and copper, and basically consists of coated diamond particles dispersed in a high conductivity metal, such as copper. The composite material can be fabricated in small or relatively large sizes using inexpensive materials. The process basically consists, for example, of sputter coating diamond powder with several elements, including a carbide forming element and a brazeable material, compacting them into a porous body, and infiltrating the porous body with a suitable braze material, such as copper-silver alloy, thereby producing a dense diamond-copper composite material with a thermal conductivity comparable to synthetic diamond films at a fraction of the cost.

  1. Facile synthesis of metastable Ni-P nanostructured materials by a novel bottom-up strategy

    NASA Astrophysics Data System (ADS)

    Bousnina, M. A.; Schoenstein, F.; Smiri, L. S.; Jouini, N.

    2015-02-01

    A novel bottom-up strategy combining chimie douce and non-conventional consolidation process to elaborate Ni-P metastable alloy is described here. The chimie douce method consists on the polyol process, modified by the addition of hypophosphite (strong reducing agent). It allows elaborating Ni-P nanopowder. The consolidation of the as-obtained nanoparticles is carried out by Spark Plasma Sintering (SPS). The microstructure of the powder and nanostructured dense sample was studied and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), thermogravimetric analysis (TGA), differential thermal analysis (DTA) and FTIR spectroscopy. The nanopowder is formed of the metastable Ni-P alloy, with a composition of about 3.44% in phosphorus. Unlike Ni-P alloys prepared by electroless or electrodeposition, the nanoparticles developed show good crystallinity. They have spherical morphologies with a size of about 100 nm and are formed by aggregation of crystallites about 8 nm in diameter. Various analysis techniques showed that SPS treatment induced the transformation of the metastable Ni-P alloy in a two phases: almost pure nickel and a new phase with chemical formula Ni3P. This latter is in form of spherical particles with about 130 nm in diameter, while the nickel grains have a polygonal shape with 330 nm in diameter.

  2. Characterization and prediction of abrasive wear of powder composite materials

    Microsoft Academic Search

    R. Veinthal; P. Kulu; J. Pirso; H. Käerdi

    2009-01-01

    Composite materials produced by powder metallurgy provide a solution in many engineering applications where materials with high abrasion and erosion resistance are required. The actual wear behaviour of the material is associated with many external factors (particle size, velocity, angularity, etc.) and intrinsic material properties (hardness, toughness, Young modulus, etc.). Hardness and toughness properties of such tribomaterials are highly dependent

  3. Characterization of a High Strain Composite Material I. Maqueda

    E-print Network

    Pellegrino, Sergio

    and developed a high-strain composite material consisting of car- bon fibers embedded in a silicone matrixCharacterization of a High Strain Composite Material I. Maqueda and S. Pellegrino California) to provide elastically foldable connections. In this case the stored strain energy in the tape springs

  4. Pistons and Cylinders Made of Carbon-Carbon Composite Materials

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)

    2000-01-01

    An improved reciprocating internal combustion engine has a plurality of engine pistons, which are fabricated from carbon---carbon composite materials, in operative association with an engine cylinder block, or an engine cylinder tube, or an engine cylinder jug, all of which are also fabricated from carbon-carbon composite materials.

  5. Pistons and Cylinders Made of Carbon-Carbon Composite Materials

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)

    2000-01-01

    An improved reciprocating internal combustion engine has a plurality of engine pistons, which are fabricated from carbon-carbon composite materials, in operative association with an engine cylinder block, or an engine cylinder tube, or an engine cylinder jug, all of which are also fabricated from carbon-carbon composite materials.

  6. CFRP\\/titanium hybrid material for improving composite bolted joints

    Microsoft Academic Search

    B. Kolesnikov; L. Herbeck; A. Fink

    2008-01-01

    The structural joining remains an essential challenge for the development of composite aerospace structures: every structural interconnection means a disturbance of an optimized structure resulting in an increase in overall structural weight. The lightweight potential of advanced, high-performance fiber composite materials is affected more strongly by mechanical fastening techniques than by conventional metallic materials due to the low shear and

  7. Industry technology assessment of graphite-polymide composite materials. [conferences

    NASA Technical Reports Server (NTRS)

    1975-01-01

    An assessment of the current state of the art and the future prospects for graphite polyimide composite material technology is presented. Presentations and discussions given at a minisymposium of major issues on the present and future use, availability, processing, manufacturing, and testing of graphite polyimide composite materials are summarized.

  8. Intelligent signal processing for damage detection in composite materials

    Microsoft Academic Search

    W. J. Staszewski

    2002-01-01

    Signal processing is an important element of any structural health monitoring system. The paper addresses the importance of intelligent signal processing for damage identification in composite materials. After an initial discussion as to what constitutes the overall signal processing, a number of examples of damage detection in composite materials are presented for illustration. These include: data denoising techniques, feature extraction

  9. Research on damage detection of composite materials based on RBFNN

    Microsoft Academic Search

    Dong Xiaoma; Sun Qingzhen

    2010-01-01

    A dynamic method based on hybrid algorithm RBFNN for damage identification of composite materials was proposed. By using wavelet series, the features of signals were extracted and input to hybrid algorithm RBFNN for training the network and identifying the damages. Finally, the experiment results show that this method can exactly identify the faults of composite materials.

  10. Damage detection in composite materials using frequency response methods

    Microsoft Academic Search

    Seth S. Kessler; S. Mark Spearing; Mauro J. Atalla; Carlos E. S. Cesnik; Constantinos Soutis

    2002-01-01

    Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents part of an experimental and analytical survey of candidate methods for the in situ detection of damage in composite materials. The experimental results are presented for the application of modal analysis techniques applied to graphite\\/epoxy specimens containing representative damage modes. Changes in natural frequencies

  11. Conducting polyaniline composite: a reusable sensor material for aqueous ammonia

    Microsoft Academic Search

    Sarswati Koul; R Chandra; S. K Dhawan

    2001-01-01

    The present paper reports about polyaniline–(acrylonitrile–butadiene–styrene) composite film as a sensor material for aqueous ammonia. The resistance change of the composite film on exposure to different concentrations of aqueous ammonia shows its utility as a sensor material. The composite film on exposure to 10?4 and 10?5N aqueous ammonia shows a well-defined response behaviour and this aspect has been utilized in

  12. NASA's Reusable Launch Vehicle Technologies: A Composite Materials Overview

    NASA Technical Reports Server (NTRS)

    Clinton, R. G., Jr.; Cook, Steve; Effinger, Mike; Smith, Dennis; Swint, Shayne

    1999-01-01

    A materials overview of the NASA's Earth-to-Orbit Space Transportation Program is presented. The topics discussed are: Earth-to-Orbit Goals and Challenges; Space Transportation Program Structure; Generations of Reusable Launch Vehicles; Space Transportation Derived Requirements; X 34 Demonstrator; Fastrac Engine System; Airframe Systems; Propulsion Systems; Cryotank Structures; Advanced Materials, Fabrication, Manufacturing, & Assembly; Hot and Cooled Airframe Structures; Ceramic Matrix Composites; Ultra-High Temp Polymer Matrix Composites; Metal Matrix Composites; and PMC Lines Ducts and Valves.

  13. Chromatographic behavior of silica-polymer composite molecularly imprinted materials.

    PubMed

    Tóth, B; László, K; Horvai, G

    2005-12-23

    Molecularly imprinted polymers (MIP) have recently been prepared inside the pores of silica based HPLC packing materials. Detailed physical and chromatographic characterization of such a silica-MIP composite material is presented. The chromatographic peak shape obtained with the uniformly sized spherical silica-MIP composite is mainly determined by the nonlinear adsorption isotherm. Comparison of the composite with the conventional sieved and grinded bulk MIP is therefore based on the nonlinear isotherm and not on retention factors and plate numbers. PMID:16188268

  14. Modeling and simulation of manufacturing processes of advanced composite materials

    NASA Astrophysics Data System (ADS)

    Lee, Woo I.; Springer, George S.

    Models for autoclave curing of thermosetting matrix composites are briefly described along with models of manufacturing process models for thermoplastic matrix composites. These models can be used to obtain optimum cure cycles of composite materials. They are particularly useful since the cure cycle must be modified to account for the effect of internal heat generation at the thickness of composite laminate changes. They can be indispensable tools in finding appropriate rules for optimum cure cycles via expert systems.

  15. Advances in thermoplastic matrix composite materials

    SciTech Connect

    Newaz, G.M.

    1989-01-01

    Accounts are given of the development status of thermoplastic composite processing methods, as well as their current thermal and mechanical behavior and delamination properties. Attention is given to the thermoplastic coating of carbon fibers, pultrusion-process modeling, the high temperature behavior of graphite/PEEK, the thermal conductivity of composites for electronic packaging, a FEM analysis of mode I and II thermoplastic-matrix specimens, and reinforcements' resin-impregnation behavior during thermoplastic composite manufacture. Also discussed are the mechanical properties of carbon fiber/PEEK for structural applications, moisture-content mechanical property effects in PPS-matrix composites, the interlaminar fracture toughness of thermoplastic composites, and thermoplastic composite delamination growth under elevated temperature cyclic loading.

  16. Environmental effects on composite materials. Volume 3

    SciTech Connect

    Springer, G.S.

    1988-01-01

    The present collection of papers, each of which has previously been abstracted in International Aerospace Abstracts, discusses the accelerated environmental testing of composites, moisture solubility and diffusion in epoxy and epoxy-glass composites, the influence of internal and external factors affecting moisture absorption in polymer composites, long-tern moisture absorption in graphite/epoxy angle-ply laminates, the effect of UV light on Kevlar 49-reinforced composites, and temperature and moisture induced deformation in composite sandwich panels. Also discussed are the orthotropic thermoelastic problem of uniform heat flow distributed by a central crack, the effect of microcracks on composite laminate thermal expansion, the stress analysis of wooden structures exposed to elevated temperatures, and the deflection of plastic beams at elevated temperatures.

  17. Recent progress of smart composite material in HIT

    NASA Astrophysics Data System (ADS)

    Leng, Jinsong; Yu, Kai; Liu, Yanju

    2009-12-01

    Recent progresses of smart composite material in our ongoing research are presented in this paper. In recent years, shape memory polymers (SMPs) and electroactive polymers (EAPs) attract more and more attention in the world. In our researching work, different kinds of reinforcement are embedded into SMPs and EAPs to form smart composite materials, aiming to improve the properties or strengthen the materials. Based on the unique properties of SMP based smart composite materials, primary application in the deployable morphing wing are also studied, which provide meaningful guidance for further researching works in this area.

  18. Recent progress of smart composite material in HIT

    NASA Astrophysics Data System (ADS)

    Leng, Jinsong; Yu, Kai; Liu, Yanju

    2010-03-01

    Recent progresses of smart composite material in our ongoing research are presented in this paper. In recent years, shape memory polymers (SMPs) and electroactive polymers (EAPs) attract more and more attention in the world. In our researching work, different kinds of reinforcement are embedded into SMPs and EAPs to form smart composite materials, aiming to improve the properties or strengthen the materials. Based on the unique properties of SMP based smart composite materials, primary application in the deployable morphing wing are also studied, which provide meaningful guidance for further researching works in this area.

  19. Corrosion inhibiting composition for treating asbestos containing materials

    DOEpatents

    Hartman, Judithann Ruth (Columbia, MD)

    1998-04-21

    A composition for transforming a chrysotile asbestos-containing material into a non-asbestos material is disclosed, wherein the composition comprises water, at least about 30% by weight of an acid component, optionally a source of fluoride ions, and a corrosion inhibiting amount of thiourea, a lower alkylthiourea, a C.sub.8 -C.sub.15 alkylpyridinium halide or mixtures thereof. A method of transforming an asbestos-containing building material, while part of a building structure, into a non-asbestos material by using the present composition also is disclosed.

  20. Composite materials: Fatigue and fracture. Vol. 3

    NASA Technical Reports Server (NTRS)

    O'Brien, T. K. (editor)

    1991-01-01

    The present volume discusses topics in the fields of matrix cracking and delamination, interlaminar fracture toughness, delamination analysis, strength and impact characteristics, and fatigue and fracture behavior. Attention is given to cooling rate effects in carbon-reinforced PEEK, the effect of porosity on flange-web corner strength, mode II delamination in toughened composites, the combined effect of matrix cracking and free edge delamination, and a 3D stress analysis of plain weave composites. Also discussed are the compression behavior of composites, damage-based notched-strength modeling, fatigue failure processes in aligned carbon-epoxy laminates, and the thermomechanical fatigue of a quasi-isotropic metal-matrix composite.

  1. A low temperature Co-fired ceramic-based dielectrophoretic device for manipulating micro and nanostructure materials.

    PubMed

    Seon, Ji-Yun; Yoon, Young Joon; Choi, Jaekyoung; Kim, Hyo Tae; Kim, Chang-Yeoul; Kim, Jong-Hee; Baik, Hong Koo

    2013-11-01

    A dielectophoretic (DEP) device fabricated by a conventional low temperature co-fired ceramic (LTCC) process, for manipulating micro and nanostructure materials, such as spherical polystyrene microspheres, titanium dioxide (TiO2) nanotubes, and silver (Ag) nanowires, is described. To generate a non-uniform electric field, a castellated electrode configuration was applied to the LTCC-based DEP device using a screen printing method. The actual motions of the micro and nanostructure materials under both a positive and a negative DEP force were observed in detail and the findings compared with numerical simulation data for the electric field distribution. The performance of the LTCC-based DEP device for separating and trapping was evaluated and potential applications are discussed. PMID:24245288

  2. Nanostructures for Energy Application: Synthesis, Characterization and Advanced Applications

    E-print Network

    Vardi, Amichay

    , shape, and composition. The synthesis of 1-dimensional nanostructures is conducted by gas- and solution and composition Control of nanostructures Synthesis of nanowires and other structures using gas phase techniquesNanostructures for Energy Application: Synthesis, Characterization and Advanced Applications

  3. Predictive rendering of composite materials: a multi-scale approach

    NASA Astrophysics Data System (ADS)

    Muller, T.; Callet, P.; da Graça, F.; Paljic, A.; Porral, P.; Hoarau, R.

    2015-03-01

    Predictive rendering of material appearance means going deep into the understanding of the physical interaction between light and matter and how these interactions are perceived by the human brain. In this paper we describe our approach to predict the appearance of composite materials by relying on the multi-scale nature of the involved phenomena. Using recent works on physical modeling of complex materials, we show how to predict the aspect of a composite material based on its composition and its morphology. Specifically, we focus on the materials whose morphological structures are defined at several embedded scales. We rely on the assumption that when the inclusions in a composite material are smaller than the considered wavelength, the optical constants of the corresponding effective media can be computed by a homogenization process (or analytically for special cases) to be used into the Fresnel formulas.

  4. Wear resistance of composite materials. (Latest citations from Engineered Materials abstracts). Published Search

    SciTech Connect

    Not Available

    1994-09-01

    The bibliography contains citations concerning wear resistance of composite materials. References discuss polymer, ceramic and metal composites. Tribological testing and failure analyses are included. (Contains a minimum of 200 citations and includes a subject term index and title list.)

  5. Multilayer composite material and method for evaporative cooling

    NASA Technical Reports Server (NTRS)

    Buckley, Theresa M. (Inventor)

    2002-01-01

    A multilayer composite material and method for evaporative cooling of a person employs an evaporative cooling liquid that changes phase from a liquid to a gaseous state to absorb thermal energy. The evaporative cooling liquid is absorbed into a superabsorbent material enclosed within the multilayer composite material. The multilayer composite material has a high percentage of the evaporative cooling liquid in the matrix. The cooling effect can be sustained for an extended period of time because of the high percentage of phase change liquid that can be absorbed into the superabsorbent. Such a composite can be used for cooling febrile patients by evaporative cooling as the evaporative cooling liquid in the matrix changes from a liquid to a gaseous state to absorb thermal energy. The composite can be made with a perforated barrier material around the outside to regulate the evaporation rate of the phase change liquid. Alternatively, the composite can be made with an imperveous barrier material or semipermeable membrane on one side to prevent the liquid from contacting the person's skin. The evaporative cooling liquid in the matrix can be recharged by soaking the material in the liquid. The multilayer composite material can be fashioned into blankets, garments and other articles.

  6. Characterization of nanostructured photosensitive (NiS){sub x}(CdS){sub (1-x)} composite thin films grown by successive ionic layer adsorption and reaction (SILAR) route

    SciTech Connect

    Ubale, A.U., E-mail: ashokuu@yahoo.com [Nanostructured Thin Film Materials Laboratory, Department of Physics, Govt. Vidarbha Institute of Science and Humanities, Amravati 444604, Maharashtra (India); Bargal, A.N. [Nanostructured Thin Film Materials Laboratory, Department of Physics, Govt. Vidarbha Institute of Science and Humanities, Amravati 444604, Maharashtra (India)] [Nanostructured Thin Film Materials Laboratory, Department of Physics, Govt. Vidarbha Institute of Science and Humanities, Amravati 444604, Maharashtra (India)

    2011-07-15

    Highlights: {yields} Thin films of (NiS){sub x}(CdS){sub (1-x)} with variable composition (x = 1 to 0) were deposited onto glass substrates by the successive ionic layer adsorption and reaction (SILAR) method. {yields} The structural, surface morphological and electrical characterizations of the as deposited and annealed films were studied. {yields} The bandgap and activation energy of annealed (NiS){sub x}(CdS){sub (1-x)} film decrease with improvement in photosensitive nature. -- Abstract: Recently ternary semiconductor nanostructured composite materials have attracted the interest of researchers because of their photovoltaic applications. Thin films of (NiS){sub x}(CdS){sub (1-x)} with variable composition (x = 1-0) had been deposited onto glass substrates by the successive ionic layer adsorption and reaction (SILAR) method. As grown and annealed films were characterised by X-ray diffraction, scanning electron microscopy and EDAX to investigate structural and morphological properties. The (NiS){sub x}(CdS){sub (1-x)} films were polycrystalline in nature having mixed phase of rhombohedral and hexagonal crystal structure due to NiS and CdS respectively. The optical and electrical properties of (NiS){sub x}(CdS){sub (1-x)} thin films were studied to determine compsition dependent bandgap, activation energy and photconductivity. The bandgap and activation energy of annealed (NiS){sub x}(CdS){sub (1-x)} film decrease with improvement in photosensitive nature.

  7. Fluorescent-Magnetic Hybrid Nanostructures: Preparation, Properties, and Applications in Biology

    Microsoft Academic Search

    Alessandra Quarta; Riccardo Di Corato; Liberato Manna; Andrea Ragusa

    2007-01-01

    Research on nanocomposite materials aims at developing nanoscale composites with innovative optical, chemical, and magnetic properties, all combined in one single nanostructure. In this scenario, nanostructures which show simultaneously fluorescent and magnetic features are of particular interest for pharmaceutical and biomedical applications. In this review, we will focus our attention on magnetic-fluorescent nanocomposite based on colloidal iron oxide nanocrystals combined

  8. SOFC ANODE MATERIALS Most common SOFC anode materials are Ni-YSZ composites

    E-print Network

    Mease, Kenneth D.

    MATERIALS SOFC ANODE MATERIALS OVERVIEW Most common SOFC anode materials are Ni-YSZ composites for the anode of a reversible SOFC · Develop a novel sol-gel process for synthesis of SYT · Use the novel sol for use in reversible SOFC anodes · Manufacture composite SYT anodes (with LDC, LSGMC) and test them

  9. High power 4.7 V nanostructured spinel lithium manganese nickel oxide lithium-ion battery cathode materials

    Microsoft Academic Search

    Muharrem Kunduraci

    2007-01-01

    Nanostructured LiMn1.5+deltaNi0.5-deltaO 4 spinel powders were synthesized by a solution based chemistry method called modified Pechini. The impacts of processing parameters such as synthesis temperature, oxygen-partial-pressure and mole ratio of ethylene glycol to citric acid on the morphology, structure and properties of spinel materials have been studied thoroughly via various in-situ and ex-situ characterization techniques. Later, these parameters were tied

  10. Functional ceria–salt-composite materials for advanced ITSOFC applications

    Microsoft Academic Search

    Bin Zhu

    2003-01-01

    This paper reports our current material research and development for advanced intermediate temperature (IT, 400–700°C) solid oxide fuel cells (SOFCs). The materials reported in this work are based on ceria–salt-composites, which have super function, e.g. displaying ionic conductivity of 0.01–1Scm?1 in the IT region. They are functional ceramic materials for advanced ITSOFC applications. When these new composites are used as

  11. Polymeric compositions incorporating polyethylene glycol as a phase change material

    Microsoft Academic Search

    Ival O. Salyer; Charles W. Griffen

    1989-01-01

    A polymeric composition comprising a polymeric material and polyethylene glycol or end-capped polyethylene glycol as a phase change material, said polyethylene glycol and said end-capped polyethylene glycol having a molecular weight greater than about 400 and a heat of fusion greater than about 30 cal\\/g; the composition is useful in making molded and\\/or coated materials such as flooring, tiles, wall

  12. Converting environmentally hazardous materials into clean energy using a novel nanostructured photoelectrochemical fuel cell

    SciTech Connect

    Gan, Yong X., E-mail: yong.gan@utoledo.edu [Department of Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, Toledo, OH 43606 (United States); Gan, Bo J. [Ottawa Hills High School, 2532 Evergreen Road, Toledo, OH 43606 (United States)] [Ottawa Hills High School, 2532 Evergreen Road, Toledo, OH 43606 (United States); Clark, Evan; Su, Lusheng [Department of Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, Toledo, OH 43606 (United States)] [Department of Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, Toledo, OH 43606 (United States); Zhang, Lihua [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973 (United States)] [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2012-09-15

    Highlights: ? A photoelectrochemical fuel cell has been made from TiO{sub 2} nanotubes. ? The fuel cell decomposes environmentally hazardous materials to produce electricity. ? Doping the anode with a transition metal oxide increases the visible light sensitivity. ? Loading the anode with a conducting polymer enhances the visible light absorption. -- Abstract: In this work, a novel photoelectrochemical fuel cell consisting of a titanium dioxide nanotube array photosensitive anode and a platinum cathode was made for decomposing environmentally hazardous materials to produce electricity and clean fuel. Titanium dioxide nanotubes (TiO{sub 2} NTs) were prepared via electrochemical oxidation of pure Ti in an ammonium fluoride and glycerol-containing solution. Scanning electron microscopy was used to analyze the morphology of the nanotubes. The average diameter, wall thickness and length of the as-prepared TiO{sub 2} NTs were determined. The photosensitive anode made from the highly ordered TiO{sub 2} NTs has good photo-catalytic property, as proven by the decomposition tests on urea, ammonia, sodium sulfide and automobile engine coolant under ultraviolet (UV) radiation. To improve the efficiency of the fuel cell, doping the TiO{sub 2} NTs with a transition metal oxide, NiO, was performed and the photosensitivity of the doped anode was tested under visible light irradiation. It is found that the NiO-doped anode is sensitive to visible light. Also found is that polyaniline-doped photosensitive anode can harvest photon energy in the visible light spectrum range much more efficiently than the NiO-doped one. It is concluded that the nanostructured photoelectrochemical fuel cell can generate electricity and clean fuel by decomposing hazardous materials under sunlight.

  13. Magnetic studies of mesoporous nanostructured iron oxide materials synthesized by one-step soft-templating.

    PubMed

    Jin, Jing; Hines, William A; Kuo, Chung-Hao; Perry, David M; Poyraz, Altug S; Xia, Yan; Zaidi, Taha; Nieh, Mu-Ping; Suib, Steven L

    2015-07-14

    A combined magnetization and (57)Fe spin-echo nuclear magnetic resonance (NMR) study has been carried out on mesoporous nanostructured materials consisting of the magnetite (Fe3O4) and maghemite (?-Fe2O3) phases. Two series of samples were synthesized using a recently developed one-step soft-templating approach with systematic variations in calcination temperature and reaction atmosphere. Nuclear magnetic resonance has been shown to be a valuable tool for distinguishing between the two magnetic iron oxide spinel phases, Fe3O4 and ?-Fe2O3, on the nanoscale as well as monitoring phase transformation resulting from oxidation. For the Fe3O4 and ?-Fe2O3 phases, peaks in the NMR spectra are attributed to Fe in the tetrahedral (A) sites and octahedral (B) sites. The magnetic field dependence of the peaks was observed and confirmed the site assignments. Fe3O4 on a nanoscale readily oxidizes to form ?-Fe2O3 and this was clearly evident in the NMR spectra. As evidenced by transmission electron microscope (TEM) images, the porous mesostructure for the iron oxide materials is formed by a random close-packed aggregation of nanoparticles; correspondingly, superparamagnetic behavior was observed in the magnetic measurements. Although X-ray diffraction (XRD) shows the spinel structure for the Fe3O4 and ?-Fe2O3 phases, unlike NMR, it is difficult to distinguish between the two phases with XRD. Nitrogen sorption isotherms characterize the mesoporous structures of the materials, and yield BET surface area values and limited BJH pore size distribution curves. PMID:26067028

  14. Automobile leaf springs from composite materials

    Microsoft Academic Search

    H. A. Al-Qureshi

    2001-01-01

    The automobile industry has shown increased interest in the replacement of steel springs with fiberglass reinforced composite leaf springs. Therefore, the aim of this paper is to present a general study on the analysis, design and fabrication of composite springs. From this viewpoint, the suspension spring of a compact car, “a jeep” was selected as a prototype.A single leaf, variable

  15. ADVANCEMENTS IN ENGINEERED COMPOSITE SANDWICH CORE MATERIALS

    Microsoft Academic Search

    Eric J. Lang

    Results are presented for product and design innova tions involving TYCOR ® fiber-reinforced- foam (FRF) core technology for composite sandwich construction. Low-cost FRF core-preforms used with infusion molding processes provide light, stiff composite sandwich panels and structures. Product design innovations were tested that provide more balanced primary (\\

  16. Novel composite materials synthesized by the high-temperature interaction of pyrrole with layered oxide matrices

    NASA Astrophysics Data System (ADS)

    Pavel, Alexandru Cezar

    The initial goal of the research presented herein was to develop the very first synthetic metal---high-temperature superconductor ceramic composite material, in the specific form of a polypyrrole---Bi2Sr2CaCu 2O8+delta nanocomposite. In the course of scientific investigation, this scope was broadened to encompass structurally and compositionally similar layered bismuthates and simpler layered oxides. The latter substrates were prepared through novel experimental procedures that enhanced the chance of yielding nanostructured morphologies. The designed novel synthesis approaches yielded a harvest of interesting results that may be further developed upon their dissemination in the scientific community. High-temperature interaction of pyrrole with molybdenum trioxide substrates with different crystalline phases and morphologies led to the formation of the first members of a new class of heterogeneous microcomposites characterized by incomplete occupancy by the metal oxide core of the volume encapsulated by the rigid, amorphous permeable polymeric membrane that reproduces the volume of the initial grain of precursor substrate. The method may be applied for various heterogeneous catalyst substrates for the precise determination of the catalytically active crystallographic planes. In a different project, room-temperature, templateless impregnation of molybdenum trioxide substrates with different crystalline phases and morphologies by a large excess of silver (I) cations led to the formation of 1-D nanostructured novel Ag-Mo-O ternary phase in what may be the simplest experimental procedure available to date that has yielded a 1-D nanostructure, regardless the nature of the constituent material. Interaction of this novel ternary phase with pyrrole vapors at high reaction temperatures led to heterogeneous nanostructured composites that exhibited a silver nanorod core. Nanoscrolls of vanadium pentoxide xerogel were synthesized through a novel, facile reflux-based method that employed very acidic pH levels and long reaction times. The nanoscrolls proved to be an excellent precursor for the synthesis of reduced vanadium oxide nanosheets by the redox intercalation of long chain monoamine molecules. In a related development, the very first synthetic metal---mixed-valence polyoxovanadate salt hybrid material was synthesized in the form of a polypyrrole---tetrammonium hexavanadate microcomposite by a redox simultaneous co-precipitation in an aqueous solution. The novel material displayed good mechanical properties towards solid lubricant applications and tunable electronic conductivity. Nanocomposites of polypyrrole---layered bismuthates were produced by the topotactic intercalation of pyrrole and its subsequent in situ polymerization. Insulating and superconducting layered bismuthates were used in a similar experimental procedure that used pre-intercalated iodine species as sacrificial topotactic oxidizing agents. A novel method of iodine intercalation by a solution-based transport procedure was used in the process. Interaction of pyrrole with layered bismuthates at high reaction temperatures led to the formation of polymer-covered metal nanorods as a result of intrinsic lattice templating effect. The successful synthesis of the 1-D heterogeneous nanostructures represents the first example in which nanocomposites were used as precursors. Appropriate doping of the initial layered ceramic substrates led to polymer-covered metal alloy nanorods.

  17. Modeling of self-healing composite materials

    Microsoft Academic Search

    Alexander Dementsov

    2008-01-01

    In this thesis modeling approaches have been considered to describe healing process in self-healing materials. These materials can partially restore their mechanical properties as microcracks develop inside the material. The interest in modeling of self-healing materials comes from recent experiments [1] that show possible perspective applications in many fields of industry. Following the idea of bio-materials that can heal its

  18. Nondestructive inspection and evaluation of composite-material flywheels

    SciTech Connect

    Reifsnider, K.L.; Boyd, D.M.; Kulkarni, S.V.

    1982-02-24

    It has been demonstrated that flywheels made from composite materials are capable of storing energy with a significantly higher energy density than those made from conventional metals. Since composite materials are also very durable and inherently safer for such applications, it would appear that they will play a major role in flywheel energy-storage systems. This report addresses the question of how flywheels made from composite materials can be inspected with nondestructive test methods to establish their initial quality and their subsequent integrity during service. A variety of methods is discussed in the context of special requirements for the examination of composite flywheel structures and the results of several example nondestructive evaluations before and after spin testing are presented. Recommendations for general nondestructive testing and evaluation of composite-material flywheels are made.

  19. Synthesis, characterization and physical properties of CDW material niobium selenide and superconducting niobium nitride nanostructures

    NASA Astrophysics Data System (ADS)

    Patel, Umeshkumar

    Nanostructures are an important system by which to study electronic properties in confined geometries. This dissertation describes synthesis and properties of both charge-density-wave (CDW) (NbSe3) and superconducting (NbN) nanostructures. NbSe3 nanostructures were synthesized using stoichiometric amounts of niobium and selenium powders in an evacuated quartz tube at 700°C. These nanostructures were subsequently transformed into superconducting NbN nanostructures through annealing under ammonia gas atmosphere at temperatures up to 1000°C. Morphological characterizations were conducted with scanning electron microscopy. X-ray diffractions were used to identify the phases of the synthesized nanostructures. Four-probe resistive measurements on individual nanostructures were utilized to explore their CDW and superconducting properties in confined geometries. Magnetization measurements were also applied to reveal the superconductivity of NbN nanostructure bundles. The physical properties of both individual NbSe3 nanoribbons and bulk NbSe3 crystals (for comparison) were studied. In bulk NbSe3, Shubnikov-de Hass (SdH) oscillations were seen at low temperatures when the applied field was along the c-axis, whereas negative magnetoresistance due to confinement of electron trajectories in a magnetic field was observed in nanoribbons. The observed anisotropy of magnetoresistance in NbSe 3 for magnetic fields perpendicular and parallel to b-axis of lower temperature CDW phase was explained in terms of the ellipsoidal shape of the Fermi surface and hence the mass anisotropy. Transport studies on individual superconducting NbN nanostructures revealed interesting oscillations in the magnetoresistance and critical current. The oscillations were periodic with more than one frequency. Comparisons with other reported work on magnetoresistance oscillations led to the conclusion that the oscillations were due to quantized flux passing through phase coherent loops of grains.

  20. Computer Code for Nanostructure Simulation

    NASA Technical Reports Server (NTRS)

    Filikhin, Igor; Vlahovic, Branislav

    2009-01-01

    Due to their small size, nanostructures can have stress and thermal gradients that are larger than any macroscopic analogue. These gradients can lead to specific regions that are susceptible to failure via processes such as plastic deformation by dislocation emission, chemical debonding, and interfacial alloying. A program has been developed that rigorously simulates and predicts optoelectronic properties of nanostructures of virtually any geometrical complexity and material composition. It can be used in simulations of energy level structure, wave functions, density of states of spatially configured phonon-coupled electrons, excitons in quantum dots, quantum rings, quantum ring complexes, and more. The code can be used to calculate stress distributions and thermal transport properties for a variety of nanostructures and interfaces, transport and scattering at nanoscale interfaces and surfaces under various stress states, and alloy compositional gradients. The code allows users to perform modeling of charge transport processes through quantum-dot (QD) arrays as functions of inter-dot distance, array order versus disorder, QD orientation, shape, size, and chemical composition for applications in photovoltaics and physical properties of QD-based biochemical sensors. The code can be used to study the hot exciton formation/relation dynamics in arrays of QDs of different shapes and sizes at different temperatures. It also can be used to understand the relation among the deposition parameters and inherent stresses, strain deformation, heat flow, and failure of nanostructures.