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Sample records for multilayer composite fabric

  1. Fabrication of multilayer nanowires

    NASA Astrophysics Data System (ADS)

    Kaur, Jasveer; Singh, Avtar; Kumar, Davinder; Thakur, Anup; Kaur, Raminder

    2016-05-01

    Multilayer nanowires were fabricated by potentiostate ectrodeposition template synthesis method into the pores of polycarbonate membrane. In present work layer by layer deposition of two different metals Ni and Cu in polycarbonate membrane having pore size of 600 nm were carried out. It is found that the growth of nanowires is not constant, it varies with deposition time. Scanning electron microscopy (SEM) is used to study the morphology of fabricated multilayer nanowires. An energy dispersive X-ray spectroscopy (EDS) results confirm the composition of multilayer nanowires. The result shows that multilayer nanowires formed is dense.

  2. Multilayered ceramic/metal composites by extrusion freeform fabrication

    NASA Astrophysics Data System (ADS)

    Kasichainula, Sridhar

    Metal layers within a laminar ceramic can improve damage tolerance of ceramics by arresting large cracks either by ductile bridging or by crack deflection at the ceramic/metal interface, which will allow engineers to design reliable ceramics for structural applications. At low volume fractions of the metal ductile bridging is not very effective, mainly owing to decreased distance between the crack tip and next ceramic layer. Significant increase in the energy absorption during fracture can come from delamination, but depends on the interfacial fracture resistance. A two-fold increase in energy absorption is realized in the case of glass-ceramic/silver laminates prepared by extrusion freeform fabrication. Interfacial fracture energy for glass-ceramic/silver is found to be 100 J/m2 in comparison to 15 J/m2 for glass-ceramic/SiC, which should explain the sporadic crack deflection in notched four-point bend. For a short beam flexural test shear failure is more favorable in four-point than in three-point bending. In four-point tests, the shear stresses between the outer and inner loading pins can precipitate shear delamination prior to tensile cracking of the layers. Damage modes under low velocity impact tests are similar to four-point bend showing delamination as primary energy dissipation mechanism.

  3. Some features of the fabrication of multilayer fiber composites by explosive welding

    NASA Technical Reports Server (NTRS)

    Kotov, V. A.; Mikhaylov, A. N.; Cabelka, D.

    1985-01-01

    The fabrication of multilayer fiber composites by explosive welding is characterized by intense plastic deformation of the matrix material as it fills the spaces between fibers and by high velocity of the collision between matrix layers due to acceleration in the channels between fibers. The plastic deformation of the matrix layers and fiber-matrix friction provide mechanical and thermal activation of the contact surfaces, which contributes to the formation of a bond. An important feature of the process is that the fiber-matrix adhesion strength can be varied over a wide range by varying the parameters of impulsive loading.

  4. Fabrication of graphene/polyaniline composite multilayer films by electrostatic layer-by-layer assembly

    SciTech Connect

    Cong, Jiaojiao; Chen, Yuze; Luo, Jing Liu, Xiaoya

    2014-10-15

    A novel graphene/polyaniline composite multilayer film was fabricated by electrostatic interactions induced layer-by-layer self-assembly technique, using water dispersible and negatively charged chemically converted graphene (CCG) and positively charged polyaniline (PANI) as building blocks. CCG was achieved through partly reduced graphene oxide, which remained carboxyl group on its surface. The remaining carboxyl groups not only retain the dispersibility of CCG, but also allow the growth of the multilayer films via electrostatic interactions between graphene and PANI. The structure and morphology of the obtained CCG/PANI multilayer film are characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Ultraviolet–visible absorption spectrum (UV–vis), scanning electron microscopy (SEM), Raman spectroscopy and X-Ray Diffraction (XRD). The electrochemical properties of the resulting film are studied using cyclic voltammetry (CV), which showed that the resulting CCG/PANI multilayer film kept electroactivity in neutral solution and showed outstanding cyclic stability up to 100 cycles. Furthermore, the composite film exhibited good electrocatalytic ability toward ascorbic acid (AA) with a linear response from 1×10{sup −4} to 1.2×10{sup −3} M with the detect limit of 5×10{sup −6} M. This study provides a facile and effective strategy to fabricate graphene/PANI nanocomposite film with good electrochemical property, which may find potential applications in electronic devices such as electrochemical sensor. - Graphical abstract: A novel graphene/polyaniline (CCG/PANI) film was prepared by layer-by-layer assembly. - Highlights: • A novel graphene/polyaniline (CCG/PANI) film was prepared by layer-by-layer assembly. • The water dispersible and negatively charged graphene (CCG) was used as building block. • CCG was achieved through partly reduced graphene oxide with carboxyl group on its surface. • CCG/PANI film kept

  5. Structure and mechanical properties of a multilayer carbide-hardened niobium composite material fabricated by diffusion welding

    NASA Astrophysics Data System (ADS)

    Korzhov, V. P.; Ershov, A. E.; Stroganova, T. S.; Prokhorov, D. V.

    2016-04-01

    The structure, the bending strength, and the fracture mechanism of an artificial niobium-based composite material, which is fabricated by high-pressure diffusion welding of multilayer stacks assembled from niobium foils with a two-sided carbon coating, are studied. The microstructure of the composite material is found to consist of alternating relatively plastic layers of the solid solution of carbon in niobium and hardening niobium carbide layers. The room-temperature proportional limit of the developed composite material is threefold that of the composite material fabricated from coating-free niobium foils using the proposed technology. The proportional limit of the developed composite material and the stress corresponding to the maximum load at 1100°C are 500 and 560 MPa, respectively. The developed material is considered as an alternative to Ni-Al superalloys.

  6. Multilayer Composite Pressure Vessels

    NASA Technical Reports Server (NTRS)

    DeLay, Tom

    2005-01-01

    A method has been devised to enable the fabrication of lightweight pressure vessels from multilayer composite materials. This method is related to, but not the same as, the method described in gMaking a Metal- Lined Composite-Overwrapped Pressure Vessel h (MFS-31814), NASA Tech Briefs, Vol. 29, No. 3 (March 2005), page 59. The method is flexible in that it poses no major impediment to changes in tank design and is applicable to a wide range of tank sizes. The figure depicts a finished tank fabricated by this method, showing layers added at various stages of the fabrication process. In the first step of the process, a mandrel that defines the size and shape of the interior of the tank is machined from a polyurethane foam or other suitable lightweight tooling material. The mandrel is outfitted with metallic end fittings on a shaft. Each end fitting includes an outer flange that has a small step to accommodate a thin layer of graphite/epoxy or other suitable composite material. The outer surface of the mandrel (but not the fittings) is covered with a suitable release material. The composite material is filament- wound so as to cover the entire surface of the mandrel from the step on one end fitting to the step on the other end fitting. The composite material is then cured in place. The entire workpiece is cut in half in a plane perpendicular to the axis of symmetry at its mid-length point, yielding two composite-material half shells, each containing half of the foam mandrel. The halves of the mandrel are removed from within the composite shells, then the shells are reassembled and bonded together with a belly band of cured composite material. The resulting composite shell becomes a mandrel for the subsequent steps of the fabrication process and remains inside the final tank. The outer surface of the composite shell is covered with a layer of material designed to be impermeable by the pressurized fluid to be contained in the tank. A second step on the outer flange of

  7. Superabsorbent Multilayer Fabric

    NASA Technical Reports Server (NTRS)

    Coreale, J. V.; Dawn, F. S.

    1982-01-01

    Material contains gel-forming polymer and copolymer that absorb from 70 to 200 times their weight of liquid. Superabsorbent Polymer and Copolymer form gels to bind and retain liquid in multiply fabric. Until reaction between liquid and absorbent masses forms gel, backing layer retains liquids within fabric; also allows material to "breathe." Possible applications include baby diapers, female hygiene napkins, and hospital bedpads. Might also have uses in improvement of dry soil.

  8. Correlation of Microstructure and Ballistic Performance of Multilayered Zr-based Amorphous Surface Composites Fabricated by High-Energy Electron-Beam Irradiation

    NASA Astrophysics Data System (ADS)

    Do, Jeonghyeon; Jeon, Changwoo; Nam, Duk-Hyun; Kim, Choongnyun Paul; Song, Young Buem; Lee, Sunghak

    2011-05-01

    In this study, multilayered, Zr-based amorphous surface composites were fabricated by high-energy electron-beam irradiation; the correlation of their microstructure, hardness, compressive properties, and fracture properties with ballistic performance was investigated. The mixture of Zr-based amorphous powders and LiF + MgF2 flux powders was deposited on a pure Ti substrate or a plain carbon steel substrate, and then an electron beam was irradiated on this powder mixture to fabricate a one-layered surface composite. The multilayered surface composite was fabricated by an irradiating electron beam several times again onto the powder mixture deposited on the one-layered surface composite. The microstructural analysis results indicated that a small amount of fine crystalline particles was distributed homogeneously in the surface composite layer. Because the surface composite layers absorbed the ballistic impact energy by forming many cracks or microcracks, the surface composite plates were not perforated during the ballistic impact test. On the one hand, in the surface composite without containing ductile β phases, the composite layer was cracked completely and fallen off from the substrate. On the other hand, a small amount of fragmentation was found in the impacted area of the composite containing β phases because it had the sufficient hardness and fracture toughness simultaneously for effectively blocking the traveling of a projectile, thereby improving ballistic performance.

  9. Fabrication and characteristics of a multilayered ionic polymer metal composite based on Nafion/tetraethyl orthosilicate and Nafion/MCNT nanocomposites.

    PubMed

    He, Qing-Song; Yu, Min; Ding, Yan; Dai, Zhen-Dong

    2014-10-01

    Nafion/multi-walled carbon nanotubes (Nafion/MCNT) and Nafion/tetraethyl orthosilicate (Nafion/TEOS) nanocomposites were prepared and used as starting materials in the fabrication of an ionic polymer metal composite (IPMC). Experimental data show that the Nafion/MCNT-based IPMC exhibited a blocking force that is two times higher than that of bare Nafion-based IPMC. This higher blocking force is due to the stable homogeneous dispersions of multiwalled carbon nanotubes as well as to their improved conductivity. Meanwhile, the Nafion/TEOS-based IPMC generated a blocking force that is more than two times higher than that of bare Nafion-based IPMC because of the induced channels and increased water content. In this paper, a novel Nafion membrane containing a primary Nafion/TEOS layer sandwiched between two outer Nafion/MCNT nanocomposite layers was prepared by consecutive casting of liquid solutions. By using the multilayered Nafion membrane, IPMC was carefully fabricated by electroless plating. In addition, the blocking force, displacement, and electric current of the IPMC were measured on the test apparatus. The multilayered IPMC exhibited a significantly improved blocking force of 6.5 gf as well as a long effective air-operating life time. Finally, this multilayered IPMC was successfully used to actuate the robotic fish. PMID:25942807

  10. Fabrication of wedged multilayer Laue lenses

    SciTech Connect

    Prasciolu, M.; Leontowich, A. F. G.; Krzywinski, J.; Andrejczuk, A.; Chapman, H. N.; Bajt, S.

    2015-01-01

    We present a new method to fabricate wedged multilayer Laue lenses, in which the angle of diffracting layers smoothly varies in the lens to achieve optimum diffracting efficiency across the entire pupil of the lens. This was achieved by depositing a multilayer onto a flat substrate placed in the penumbra of a straight-edge mask. The distance between the mask and the substrate was calibrated and the multilayer Laue lens was cut in a position where the varying layer thickness and the varying layer tilt simultaneously satisfy the Fresnel zone plate condition and Bragg’s law for all layers in the stack. This method can be used to extend the achievable numerical aperture of multilayer Laue lenses to reach considerably smaller focal spot sizes than achievable with lenses composed of parallel layers.

  11. Fabrication of wedged multilayer Laue lenses

    DOE PAGESBeta

    Prasciolu, M.; Leontowich, A. F. G.; Krzywinski, J.; Andrejczuk, A.; Chapman, H. N.; Bajt, S.

    2015-01-01

    We present a new method to fabricate wedged multilayer Laue lenses, in which the angle of diffracting layers smoothly varies in the lens to achieve optimum diffracting efficiency across the entire pupil of the lens. This was achieved by depositing a multilayer onto a flat substrate placed in the penumbra of a straight-edge mask. The distance between the mask and the substrate was calibrated and the multilayer Laue lens was cut in a position where the varying layer thickness and the varying layer tilt simultaneously satisfy the Fresnel zone plate condition and Bragg’s law for all layers in the stack.more » This method can be used to extend the achievable numerical aperture of multilayer Laue lenses to reach considerably smaller focal spot sizes than achievable with lenses composed of parallel layers.« less

  12. Boron containing multilayer coatings and method of fabrication

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1997-01-01

    Hard coatings are fabricated from multilayer boron/boron carbide, boron carbide/cubic boron nitride, and boron/boron nitride/boron carbide, and the fabrication thereof involves magnetron sputtering in a selected atmosphere. These hard coatings may be applied to tools and engine and other parts, as well to reduce wear on tribological surfaces and electronic devices. These boron coatings contain no morphological growth features. For example, the boron and boron carbide used in forming the multilayers are formed in an inert (e.g. argon) atmosphere, while the cubic boron nitride is formed in a reactive (e.g. nitrogen) atmosphere. The multilayer boron/boron carbide, and boron carbide/cubic boron nitride is produced by depositing alternate layers of boron, cubic boron nitride or boron carbide, with the alternate layers having a thickness of 1 nanometer to 1 micrometer, and at least the interfaces of the layers may be of a discrete or a blended or graded composition.

  13. Reactive multilayers fabricated by vapor deposition. A critical review

    DOE PAGESBeta

    Adams, D. P.

    2014-10-02

    The reactive multilayer thin films are a class of energetic materials that continue to attract attention for use in joining applications and as igniters. Generally composed of two reactants, these heterogeneous solids can be stimulated by an external source to promptly release stored chemical energy in a sudden emission of light and heat. In our critical review article, results from recent investigations of these materials are discussed. Discussion begins with a brief description of the vapor deposition techniques that provide accurate control of layer thickness and film composition. More than 50 reactive film compositions have been reported to date, withmore » most multilayers fabricated by magnetron sputter deposition or electron-beam evaporation. In later sections, we review how multilayer ignition threshold, reaction rate, and total heat are tailored via thin film design. For example, planar multilayers with nanometer-scale periodicity exhibit rapid, self-sustained reactions with wavefront velocities up to 100 m/s. Numeric and analytical models have elucidated many of the fundamental processes that underlie propagating exothermic reactions while demonstrating how reaction rates vary with multilayer design. Recent, time-resolved diffraction and imaging studies have further revealed the phase transformations and the wavefront dynamics associated with propagating chemical reactions. Many reactive multilayers (e.g., Co/Al) form product phases that are consistent with published equilibrium phase diagrams, yet a few systems, such as Pt/Al, develop metastable products. The final section highlights current and emerging applications of reactive multilayers. Examples include reactive Ni(V)/Al and Pd/Al multilayers which have been developed for localized soldering of heat-sensitive components.« less

  14. Reactive multilayers fabricated by vapor deposition. A critical review

    SciTech Connect

    Adams, D. P.

    2014-10-02

    The reactive multilayer thin films are a class of energetic materials that continue to attract attention for use in joining applications and as igniters. Generally composed of two reactants, these heterogeneous solids can be stimulated by an external source to promptly release stored chemical energy in a sudden emission of light and heat. In our critical review article, results from recent investigations of these materials are discussed. Discussion begins with a brief description of the vapor deposition techniques that provide accurate control of layer thickness and film composition. More than 50 reactive film compositions have been reported to date, with most multilayers fabricated by magnetron sputter deposition or electron-beam evaporation. In later sections, we review how multilayer ignition threshold, reaction rate, and total heat are tailored via thin film design. For example, planar multilayers with nanometer-scale periodicity exhibit rapid, self-sustained reactions with wavefront velocities up to 100 m/s. Numeric and analytical models have elucidated many of the fundamental processes that underlie propagating exothermic reactions while demonstrating how reaction rates vary with multilayer design. Recent, time-resolved diffraction and imaging studies have further revealed the phase transformations and the wavefront dynamics associated with propagating chemical reactions. Many reactive multilayers (e.g., Co/Al) form product phases that are consistent with published equilibrium phase diagrams, yet a few systems, such as Pt/Al, develop metastable products. The final section highlights current and emerging applications of reactive multilayers. Examples include reactive Ni(V)/Al and Pd/Al multilayers which have been developed for localized soldering of heat-sensitive components.

  15. Fabrication and nanoscale characterization of magnetic multilayer nanowires

    NASA Astrophysics Data System (ADS)

    Elawayeb, Mohamed

    Magnetic multilayers nanowires are scientifically fascinating and have potential industrial applications in many areas of advanced nanotechnology. These applications arise due to the nanoscale dimensions of nanostructures that lead to unique physical properties. Magnetic multilayer nanowires have been successfully produced by electrodeposition into templates. Anodic Aluminium Oxide (AAO) membranes were used as templates in this process; the templates were fabricated by anodization method in acidic solutions at a fixed voltage. The fabrication method of a range of magnetic multilayer nanowires is described in this study and their structure and dimensions were analyzed using scanning electron microscope (SEM), Transmission electron microscope (TEM) and scanning transmission electron microscopy (STEM). This study is focused on the first growth of NiFe/Pt and NiFe/Fe magnetic multilayer nanowires, which were successfully fabricated by pulse electrodeposition into the channels of porous anodic aluminium oxide (AAO) templates, and characterized at the nanoscale. Individual nanowires have uniform structure and regular periodicity. The magnetic and nonmagnetic layers are polycrystalline, with randomly oriented fcc lattice structure crystallites. Chemical compositions of the individual nanowires were analyzed using TEM equipped with energy-dispersive x-ray analysis (EDX) and electron energy loss spectrometry (EELS). The electrical and magnetoresistance properties of individual magnetic multilayer nanowires have been measured inside a SEM using two sharp tip electrodes attached to in situ nanomanipulators and a new electromagnet technique. The giant magnetoresistance (GMR) effect of individual magnetic multilayer nanowires was measured in the current - perpendicular to the plane (CPP) geometry using a new in situ method at variable magnetic field strength and different orientations..

  16. Explicit Finite Element Modeling of Multilayer Composite Fabric for Gas Turbine Engine Containment Systems. Part 2; Ballistic Impact Testing

    NASA Technical Reports Server (NTRS)

    Pereira, J. M.; Revilock, D. M.

    2004-01-01

    Under the Federal Aviation Administration's Airworthiness Assurance Center of Excellence and the Aircraft Catastrophic Failure Prevention Program, National Aeronautics and Space Administration Glenn Research Center collaborated with Arizona State University, Honeywell Engines, Systems and Services, and SRI International to develop improved computational models for designing fabric-based engine containment systems. In the study described in this report, ballistic impact tests were conducted on layered dry fabric rings to provide impact response data for calibrating and verifying the improved numerical models. This report provides data on projectile velocity, impact and residual energy, and fabric deformation for a number of different test conditions.

  17. Fabrication of multilayer pancakelike basic magnesium carbonate.

    PubMed

    Sun, Jinhe; Jia, Yongzhong; Yan Jing; Yao, Ying; Ma, Jun

    2014-10-01

    The properties of nanomaterials was strongly affected by their microstructures. Here Mg5(CO3)4(OH)2 x 4H2O multilayer pancakelike structures were fabricated successfully by reaction of MgCl2 and Na2CO3 in aqueous solution at 363 K. The growth process of nanostructures was observed by XRD and SEM. Several transition states of multilayer pancakelike basic magnesium carbonates were observed, which help to understand better the formation process of this hierarchical nanostructures. The formation mechanism of Mg5(CO3)4(OH)2 x 4H2O multilayer pancakelike structures was discussed and helical growth was proposed. The amorphous nanoparticles were formed firstly. Then nanopartilces aggregated and oriented assembly under the direction of chemical bonds with the help of water molecules. The multilayer pancakelike basic magnesium carbonates was formed by helical growth of wafers along (100) and (001) direction. The diameter and volume decreased with the increasing concentration of reactants. PMID:25942931

  18. Method of fabricating a multilayer insulation blanket

    DOEpatents

    Gonczy, John D.; Niemann, Ralph C.; Boroski, William N.

    1993-01-01

    An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

  19. Multilayer insulation blanket, fabricating apparatus and method

    DOEpatents

    Gonczy, John D.; Niemann, Ralph C.; Boroski, William N.

    1992-01-01

    An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

  20. Method of fabricating a multilayer insulation blanket

    DOEpatents

    Gonczy, J.D.; Niemann, R.C.; Boroski, W.N.

    1993-07-06

    An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

  1. Multilayer insulation blanket, fabricating apparatus and method

    DOEpatents

    Gonczy, J.D.; Niemann, R.C.; Boroski, W.N.

    1992-09-01

    An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel. 7 figs.

  2. Magnetic nanodiscs fabricated from multilayered nanowires.

    PubMed

    Min, Ji Hyun; Cho, Ji Ung; An, Boo Hyun; Choi, Daniel S; Kimlr, Young Keun

    2014-10-01

    We report a simple, high throughput synthesis method of producing magnetic nanodiscs, in which the diameter and thickness are easily controlled. This method consists of two steps: (1) Electrodeposition for growing multilayered nanowires and (2) Selective etching of sacrificial layers. The electrodeposition step results in a bundle of multilayered nanowires. The nanowires consist of alternating layers of magnetic (e.g., Co) and sacrificial materials (e.g., Cu) inside the nanometer-sized pores of an anodized aluminum oxide (AAO) template. The diameter of each layer is determined by pore size, while the thickness is controlled by electrodeposition time. The selective wet etching step removes sacrificial layers, leaving the magnetic nanodiscs. Through this process, the magnetic nanodiscs are fabricated with aspect ratios ranging from 0.25 to 2.0. PMID:25942895

  3. Impact on multilayered composite plates

    NASA Technical Reports Server (NTRS)

    Kim, B. S.; Moon, F. C.

    1977-01-01

    Stress wave propagation in a multilayer composite plate due to impact was examined by means of the anisotropic elasticity theory. The plate was modelled as a number of identical anisotropic layers and the approximate plate theory of Mindlin was then applied to each layer to obtain a set of difference-differential equations of motion. Dispersion relations for harmonic waves and correction factors were found. The governing equations were reduced to difference equations via integral transforms. With given impact boundary conditions these equations were solved for an arbitrary number of layers in the plate and the transient propagation of waves was calculated by means of a Fast Fourier Transform algorithm. The multilayered plate problem was extended to examine the effect of damping layers present between two elastic layers. A reduction of the interlaminar normal stress was significant when the thickness of damping layer was increased but the effect was mostly due to the softness of the damping layer. Finally, the problem of a composite plate with a crack on the interlaminar boundary was formulated.

  4. Boron containing multilayer coatings and method of fabrication

    DOEpatents

    Makowiecki, D.M.; Jankowski, A.F.

    1997-09-23

    Hard coatings are fabricated from multilayer boron/boron carbide, boron carbide/cubic boron nitride, and boron/boron nitride/boron carbide, and the fabrication thereof involves magnetron sputtering in a selected atmosphere. These hard coatings may be applied to tools and engine and other parts, as well to reduce wear on tribological surfaces and electronic devices. These boron coatings contain no morphological growth features. For example, the boron and boron carbide used in forming the multilayers are formed in an inert (e.g. argon) atmosphere, while the cubic boron nitride is formed in a reactive (e.g. nitrogen) atmosphere. The multilayer boron/boron carbide, and boron carbide/cubic boron nitride is produced by depositing alternate layers of boron, cubic boron nitride or boron carbide, with the alternate layers having a thickness of 1 nanometer to 1 micrometer, and at least the interfaces of the layers may be of a discrete or a blended or graded composition. 6 figs.

  5. Multilayer composites and manufacture of same

    DOEpatents

    Holesinger, Terry G.; Jia, Quanxi

    2006-02-07

    The present invention is directed towards a process of depositing multilayer thin films, disk-shaped targets for deposition of multilayer thin films by a pulsed laser or pulsed electron beam deposition process, where the disk-shaped targets include at least two segments with differing compositions, and a multilayer thin film structure having alternating layers of a first composition and a second composition, a pair of the alternating layers defining a bi-layer wherein the thin film structure includes at least 20 bi-layers per micron of thin film such that an individual bi-layer has a thickness of less than about 100 nanometers.

  6. Weaving multi-layer fabrics for reinforcement of engineering components

    NASA Technical Reports Server (NTRS)

    Hill, B. J.; Mcilhagger, R.; Mclaughlin, P.

    1993-01-01

    The performance of interlinked, multi-layer fabrics and near net shape preforms for engineering applications, woven on a 48 shaft dobby loom using glass, aramid, and carbon continuous filament yarns is assessed. The interlinking was formed using the warp yarns. Two basic types of structure were used. The first used a single warp beam and hence each of the warp yarns followed a similar path to form four layer interlinked reinforcements and preforms. In the second two warp beams were used, one for the interlinking yarns which pass from the top to the bottom layer through-the-thickness of the fabric and vice versa, and the other to provide 'straight' yarns in the body of the structure to carry the axial loading. Fabrics up to 15mm in thickness were constructed with varying amounts of through-the-thickness reinforcement. Tapered T and I sections were also woven, with the shaping produced by progressive removal of ends during construction. These fabrics and preforms were impregnated with resin and cured to form composite samples for testing. Using these two basic types of construction, the influence of reinforcement construction and the proportion and type of interlinking yarn on the performance of the composite was assessed.

  7. Natural Curaua Fiber-Reinforced Composites in Multilayered Ballistic Armor

    NASA Astrophysics Data System (ADS)

    Monteiro, Sergio Neves; Louro, Luis Henrique Leme; Trindade, Willian; Elias, Carlos Nelson; Ferreira, Carlos Luiz; de Sousa Lima, Eduardo; Weber, Ricardo Pondé; Miguez Suarez, João Carlos; da Silva Figueiredo, André Ben-Hur; Pinheiro, Wagner Anacleto; da Silva, Luis Carlos; Lima, Édio Pereira

    2015-10-01

    The performance of a novel multilayered armor in which the commonly used plies of aramid fabric layer were replaced by an equal thickness layer of distinct curaua fiber-reinforced composites with epoxy or polyester matrices was assessed. The investigated armor, in addition to its polymeric layer (aramid fabric or curaua composite), was also composed of a front Al2O3 ceramic tile and backed by an aluminum alloy sheet. Ballistic impact tests were performed with actual 7.62 caliber ammunitions. Indentation in a clay witness, simulating human body behind the back layer, attested the efficacy of the curaua-reinforced composite as an armor component. The conventional aramid fabric display a similar indentation as the curaua/polyester composite but was less efficient (deeper indentation) than the curaua/epoxy composite. This advantage is shown to be significant, especially in favor of the lighter and cheaper epoxy composite reinforced with 30 vol pct of curaua fiber, as possible substitute for aramid fabric in multilayered ballistic armor for individual protection. Scanning electron microscopy revealed the mechanism associated with the curaua composite ballistic performance.

  8. Photo-crosslinkable polymers for fabrication of photonic multilayer sensors

    NASA Astrophysics Data System (ADS)

    Chiappelli, Maria; Hayward, Ryan C.

    2013-03-01

    We have used photo-crosslinkable polymers to fabricate photonic multilayer sensors. Benzophenone is utilized as a covalently incorporated pendent photo-crosslinker, providing a convenient means of fabricating multilayer films by sequential spin-coating and crosslinking processes. Colorimetric temperature sensors were designed from thermally-responsive, low-refractive index poly(N-isopropylacrylamide) (PNIPAM) and high-refractive index poly(para-methyl styrene) (P pMS). Copolymer chemistries and layer thicknesses were selected to provide robust multilayer sensors which show color changes across nearly the full visible spectrum due to changes in temperature of the hydrated film stack. We have characterized the uniformity and interfacial broadening within the multilayers, the kinetics of swelling and de-swelling, and the reversibility over multiple hydration/dehydration cycles. We also describe how the approach can be extended to alternative sensor designs through the ability to tailor each layer independently, as well as to additional stimuli by selecting alternative copolymer chemistries.

  9. Continuous multilayered composite hydrogel as osteochondral substitute.

    PubMed

    Leone, G; Volpato, M D; Nelli, N; Lamponi, S; Boanini, E; Bigi, A; Magnani, A

    2015-08-01

    Cartilage is a highly organized avascular soft tissue that assembles from nano-to macro-scale to produce a complex structural network. To mimic cartilage tissue, we developed a stable multilayered composite material, characterized by a tailored gradient of mechanical properties. The optimized procedure implies chemical crosslinking of each layer directly onto the previous one and ensures a drastic reduction of the material discontinuities and brittleness. The multilayered composite was characterized by infrared spectroscopy, differential scanning calorimetry, thermogravimetry, and scanning electron microscopy in order to compare its physico-chemical characteristics with those of cartilage tissue. The rheological behavior of the multilayered composite was similar to that of human cartilage. Finally its cytocompatibility toward chondrocytes and osteoblasts was evaluated. PMID:25504681

  10. Computerized multilevel analysis for multilayered fiber composites

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1972-01-01

    A FORTRAN 4 computer code for the micromechanics, macromechanics, and laminate analysis of multilayered fiber composite structural components is described. The code can be used either individually or as a subroutine within a complex structural analysis/synthesis program. The inputs to the code are constituent materials properties, composite geometry, and loading conditions. The outputs are various properties for ply and composite; composite structural response, including bending-stretching coupling; and composite stress analysis, including comparisons with failure criteria for combined stress. The code was used successfully in the analysis and structural synthesis of flat panels, in the buckling analysis of flat panels, in multilayered composite material failure studies, and lamination residual stresses analysis.

  11. Multilayer Electroactive Polymer Composite Material

    NASA Technical Reports Server (NTRS)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2011-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  12. Desktop aligner for fabrication of multilayer microfluidic devices

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Yu, Zeta Tak For; Geraldo, Dalton; Weng, Shinuo; Alve, Nitesh; Dun, Wu; Kini, Akshay; Patel, Karan; Shu, Roberto; Zhang, Feng; Li, Gang; Jin, Qinghui; Fu, Jianping

    2015-07-01

    Multilayer assembly is a commonly used technique to construct multilayer polydimethylsiloxane (PDMS)-based microfluidic devices with complex 3D architecture and connectivity for large-scale microfluidic integration. Accurate alignment of structure features on different PDMS layers before their permanent bonding is critical in determining the yield and quality of assembled multilayer microfluidic devices. Herein, we report a custom-built desktop aligner capable of both local and global alignments of PDMS layers covering a broad size range. Two digital microscopes were incorporated into the aligner design to allow accurate global alignment of PDMS structures up to 4 in. in diameter. Both local and global alignment accuracies of the desktop aligner were determined to be about 20 μm cm-1. To demonstrate its utility for fabrication of integrated multilayer PDMS microfluidic devices, we applied the desktop aligner to achieve accurate alignment of different functional PDMS layers in multilayer microfluidics including an organs-on-chips device as well as a microfluidic device integrated with vertical passages connecting channels located in different PDMS layers. Owing to its convenient operation, high accuracy, low cost, light weight, and portability, the desktop aligner is useful for microfluidic researchers to achieve rapid and accurate alignment for generating multilayer PDMS microfluidic devices.

  13. Desktop aligner for fabrication of multilayer microfluidic devices

    PubMed Central

    Li, Xiang; Yu, Zeta Tak For; Geraldo, Dalton; Weng, Shinuo; Alve, Nitesh; Dun, Wu; Kini, Akshay; Patel, Karan; Shu, Roberto; Zhang, Feng; Li, Gang; Jin, Qinghui; Fu, Jianping

    2015-01-01

    Multilayer assembly is a commonly used technique to construct multilayer polydimethylsiloxane (PDMS)-based microfluidic devices with complex 3D architecture and connectivity for large-scale microfluidic integration. Accurate alignment of structure features on different PDMS layers before their permanent bonding is critical in determining the yield and quality of assembled multilayer microfluidic devices. Herein, we report a custom-built desktop aligner capable of both local and global alignments of PDMS layers covering a broad size range. Two digital microscopes were incorporated into the aligner design to allow accurate global alignment of PDMS structures up to 4 in. in diameter. Both local and global alignment accuracies of the desktop aligner were determined to be about 20 μm cm−1. To demonstrate its utility for fabrication of integrated multilayer PDMS microfluidic devices, we applied the desktop aligner to achieve accurate alignment of different functional PDMS layers in multilayer microfluidics including an organs-on-chips device as well as a microfluidic device integrated with vertical passages connecting channels located in different PDMS layers. Owing to its convenient operation, high accuracy, low cost, light weight, and portability, the desktop aligner is useful for microfluidic researchers to achieve rapid and accurate alignment for generating multilayer PDMS microfluidic devices. PMID:26233409

  14. Direct-write fabrication of integrated, multilayer ceramic components

    SciTech Connect

    Dimos, D.; Yang, P.; Garino, T.J.; Raymond, M.V.; Rodriguez, M.A.

    1997-08-01

    The need for advanced (electronic) ceramic components with smaller size, greater functionality, and enhanced reliability requires the ability to integrate electronic ceramics in complex 3-D architectures. For rapid prototyping and small-lot manufacturing, traditional tape casting and screen printing approaches are poorly suited. To address this need, the authors are developing a direct-write approach for fabricating highly integrated, multilayer components using a micropen to deposit slurries in precise patterns. With this technique, components can be constructed layer by layer, simplifying fabrication. It can also be used to produce structures combining several materials in a single layer. The parts are either cofired or sequentially fired, after each layer is deposited. Since differential shrinkage can lead to defects in these multilayer structures, they are characterizing the sintering behavior of individual layers. This technique has been used to fabricate devices such integrated RC filters, multilayer voltage transformers, and other passive components. The direct-write approach provides the ability to fabricate multifunctional, multimaterial integrated ceramic components (MMICCs) in an agile and rapid way.

  15. Thermal performance of multilayer insulations. [gas evacuation characteristics of three selected multilayer insulation composites

    NASA Technical Reports Server (NTRS)

    Keller, C. W.; Cunnington, G. R.; Glassford, A. P.

    1974-01-01

    Experimental and analytical studies were conducted in order to extend previous knowledge of the thermal performance and gas evacuation characteristics of three selected multilayer insulation (MLI) composites. Flat plate calorimeter heat flux measurements were obtained for 20- and 80- shield specimens using three representative layer densities over boundary temperatures ranging from 39 K (70 R) to 389 K (700 R). Laboratory gas evacuation tests were performed on representative specimens of each MLI composite after initially purging them with helium, nitrogen, or argon gases. In these tests, the specimens were maintained at temperatures between 128 K (230 R) and 300 K (540 R). Based on the results of the laboratory-scale tests, a composite MLI system consisting of 112 unperforated, double-aluminized Mylar reflective shields and 113 water preconditioned silk net spacer pairs was fabricated and installed on a 1.22-m-(4-ft-) diameter calorimeter tank.

  16. 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.

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

    DOEpatents

    Barbee, Jr., Troy W.; Johnson, Gary W.; O'Brien, Dennis W.

    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.

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

    DOEpatents

    Barbee, Jr., Troy W.; Johnson, Gary W.; O'Brien, Dennis W.

    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.

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

    DOEpatents

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

    1995-05-09

    A high performance capacitor 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.

  20. Fabrication of Transparent Multilayer Circuits by Inkjet Printing.

    PubMed

    Jiang, Jieke; Bao, Bin; Li, Mingzhu; Sun, Jiazhen; Zhang, Cong; Li, Yang; Li, Fengyu; Yao, Xi; Song, Yanlin

    2016-02-17

    Conductive microcables embedded in a transparent film are fabricated by inkjet printing silver-nanoparticle ink into a liquid poly(dimethylsiloxane) (PDMS) precursor substrate. By controlling the spreading of the ink droplet and the rheological properties of the liquid substrate, transparent multilayer circuits composed of high-resolution embedded cables are achieved using a commercial inkjet printer. This facile strategy provides a new avenue for inkjet printing of highly integrated and transparent electronics. PMID:26643356

  1. Explicit Finite Element Modeling of Multilayer Composite Fabric for Gas Turbine Engine Containment Systems, Phase II. Part 2; Ballistic Impact Testing

    NASA Technical Reports Server (NTRS)

    Revilock, D. M.; Pereira, J. M.

    2009-01-01

    This report summarizes the ballistic impact testing that was conducted to provide validation data for the development of numerical models of blade-out events in fabric containment systems. The ballistic impact response of two different fiber materials - Kevlar(TradeName) 49 and Zylon(TradeName) AS (as spun) was studied by firing metal projectiles into dry woven fabric specimens using a gas gun. The shape, mass, orientation, and velocity of the projectile were varied and recorded. In most cases, the tests were designed so the projectile would perforate the specimen, allowing measurement of the energy absorbed by the fabric. The results for both Zylon and Kevlar presented here represent a useful set of data for the purposes of establishing and validating numerical models to predict the response of fabrics under conditions that simulate those of a jet engine blade-release situation. In addition, some useful empirical observations were made regarding the effects of projectile orientation and the relative performance of the different fabric materials.

  2. Explicit Finite Element Modeling of Multilayer Composite Fabric for Gas Turbine Engine Containment Systems, Phase II. Part 3; Material Model Development and Simulation of Experiments

    NASA Technical Reports Server (NTRS)

    Simmons, J.; Erlich, D.; Shockey, D.

    2009-01-01

    A team consisting of Arizona State University, Honeywell Engines, Systems & Services, the National Aeronautics and Space Administration Glenn Research Center, and SRI International collaborated to develop computational models and verification testing for designing and evaluating turbine engine fan blade fabric containment structures. This research was conducted under the Federal Aviation Administration Airworthiness Assurance Center of Excellence and was sponsored by the Aircraft Catastrophic Failure Prevention Program. The research was directed toward improving the modeling of a turbine engine fabric containment structure for an engine blade-out containment demonstration test required for certification of aircraft engines. The research conducted in Phase II began a new level of capability to design and develop fan blade containment systems for turbine engines. Significant progress was made in three areas: (1) further development of the ballistic fabric model to increase confidence and robustness in the material models for the Kevlar(TradeName) and Zylon(TradeName) material models developed in Phase I, (2) the capability was improved for finite element modeling of multiple layers of fabric using multiple layers of shell elements, and (3) large-scale simulations were performed. This report concentrates on the material model development and simulations of the impact tests.

  3. Method for fabricating beryllium-based multilayer structures

    DOEpatents

    Skulina, Kenneth M.; Bionta, Richard M.; Makowiecki, Daniel M.; Alford, Craig S.

    2003-02-18

    Beryllium-based multilayer structures and a process for fabricating beryllium-based multilayer mirrors, useful in the wavelength region greater than the beryllium K-edge (111 .ANG. or 11.1 nm). The process includes alternating sputter deposition of beryllium and a metal, typically from the fifth row of the periodic table, such as niobium (Nb), molybdenum (Mo), ruthenium (Ru), and rhodium (Rh). The process includes not only the method of sputtering the materials, but the industrial hygiene controls for safe handling of beryllium. The mirrors made in accordance with the process may be utilized in soft x-ray and extreme-ultraviolet projection lithography, which requires mirrors of high reflectivity (>60%) for x-rays in the range of 60-140 .ANG. (60-14.0 nm).

  4. Sputter deposition system for controlled fabrication of multilayers

    SciTech Connect

    Di Nardo, R.P.; Takacs, P.Z.; Majkrzak, C.F.; Stefan, P.M.

    1985-06-01

    A detailed description of a sputter deposition system constructed specifically for the fabrication of x-ray and neutron multilayer monochromators and supermirrors is given. One of the principal design criteria is to maintain precise control of film thickness and uniformity over large substrate areas. Regulation of critical system parameters is fully automated so that response to feedback control information is rapid and complicated layer thickness sequences can be deposited accurately and efficiently. The use of either dc or rf magnetron sources makes it possible to satisfy the diverse material requirements of both x-ray and neutron optics.

  5. WSi2/Si multilayer sectioning by reactive ion etching for multilayer Laue lens fabrication

    NASA Astrophysics Data System (ADS)

    Bouet, N.; Conley, R.; Biancarosa, J.; Divan, R.; Macrander, A. T.

    2010-09-01

    Reactive ion etching (RIE) has been employed in a wide range of fields such as semiconductor fabrication, MEMS (microelectromechanical systems), and refractive x-ray optics with a large investment put towards the development of deep RIE. Due to the intrinsic differing chemistries related to reactivity, ion bombardment, and passivation of materials, the development of recipes for new materials or material systems can require intense effort and resources. For silicon in particular, methods have been developed to provide reliable anisotropic profiles with good dimensional control and high aspect ratios1,2,3, high etch rates, and excellent material to mask etch selectivity. A multilayer Laue lens4 is an x-ray focusing optic, which is produced by depositing many layers of two materials with differing electron density in a particular stacking sequence where the each layer in the stack satisfies the Fresnel zone plate law. When this stack is sectioned to allow side-illumination with radiation, the diffracted exiting radiation will constructively interfere at the focal point. Since the first MLLs were developed at Argonne in the USA in 20064, there have been published reports of MLL development efforts in Japan5, and, very recently, also in Germany6. The traditional technique for sectioning multilayer Laue lens (MLL) involves mechanical sectioning and polishing7, which is labor intensive and can induce delamination or structure damage and thereby reduce yield. If a non-mechanical technique can be used to section MLL, it may be possible to greatly shorten the fabrication cycle, create more usable optics from the same amount of deposition substrate, and perhaps develop more advanced structures to provide greater stability or flexibility. Plasma etching of high aspect-ratio multilayer structures will also expand the scope for other types of optics fabrication (such as gratings, zone plates, and so-on). However, well-performing reactive ion etching recipes have been developed

  6. Method of fabricating composite structures

    NASA Technical Reports Server (NTRS)

    Sigur, W. A. (Inventor)

    1990-01-01

    A method of fabricating structures formed from composite materials by positioning the structure about a high coefficient of thermal expansion material, wrapping a graphite fiber overwrap about the structure, and thereafter heating the assembly to expand the high coefficient of thermal expansion material to forcibly compress the composite structure against the restraint provided by the graphite overwrap. The high coefficient of thermal expansion material is disposed about a mandrel with a release system therebetween, and with a release system between the material having the high coefficient of thermal expansion and the composite material, and between the graphite fibers and the composite structure. The heating may occur by inducing heat into the assembly by a magnetic field created by coils disposed about the assembly through which alternating current flows. The method permits structures to be formed without the use of an autoclave.

  7. Controlling the optical properties of composite multilayered photonic structures: effect of superposition.

    PubMed

    Mukherjee, Anupam; Ariza-Flores, A David; Balderas-Valadez, R Fabiola; Agarwal, Vivechana

    2013-07-15

    Tunability of the optical response of multilayered photonic structures has been compared with sequential (SQ) and superposition (SP) addition of refractive index profile functions. The optical response of the composite multilayered structure, formed after the SP addition of the two Bragg type refractive index profile functions has been studied as a function of percentage overlap and relative shift between the profiles. Apart from the substantial advantage in terms of the reduced physical thickness of the SP composite structures (over the SQ addition), at certain optimum values of relative shift, photonic structures with better quality factor resonant modes or a broader PBG could be designed. Similar analysis has been extended for rugate filters as well. The experimental verification of the optical response, was carried out through multilayered dielectric porous silicon structures fabricated by electrochemical anodization. PMID:23938579

  8. Low cost damage tolerant composite fabrication

    NASA Technical Reports Server (NTRS)

    Palmer, R. J.; Freeman, W. T.

    1988-01-01

    The resin transfer molding (RTM) process applied to composite aircraft parts offers the potential for using low cost resin systems with dry graphite fabrics that can be significantly less expensive than prepreg tape fabricated components. Stitched graphite fabric composites have demonstrated compression after impact failure performance that equals or exceeds that of thermoplastic or tough thermoset matrix composites. This paper reviews methods developed to fabricate complex shape composite parts using stitched graphite fabrics to increase damage tolerance with RTM processes to reduce fabrication cost.

  9. Multilayered titanium-steel composite produced by explosive welding

    NASA Astrophysics Data System (ADS)

    Malyutina, Yu. N.; Skorohod, K. A.; Shevtsova, K. E.; Chesnokova, A. V.

    2015-10-01

    Multilayered titanium-steel composite consisting of alternating high-strength and ductile metallic materials were produced by explosive welding. Different types of weld joints formed in the composite were recognized by methods of microstructural analysis. Wave-shaped and flat geometry of welds are typical of steel and titanium layers, respectively. Structural features such as lack of penetration, shear bands, recrystallized metals and martensitic structure were detected in the vortex and weld-adjacent zones of impacted materials. The impact strength of the layered composite was 65% higher as compared to that of VT23 titanium alloy. A favorable role of interlayers in the multilayered composite has been confirmed by toughness tests.

  10. Guided waves in a multilayered composite and ultrasonic nondestructive evaluation

    NASA Technical Reports Server (NTRS)

    Datta, S. K.; Karunasena, W. M.; Shah, A. H.

    1991-01-01

    Analysis of wave propagation in a laminated composite plate with many layers is made difficult by the anisotropy of the laminae, different lay-ups, many layers and defects in the fabricated plate. A good understanding of the wave field in such a plate without defects is a prerequisite for use of ultrasonic techniques to evaluate the various defects that can substantially reduce the strength and service life of this structure. Results of modeling studies of wave propagation and scattering in a multilayered composite plate are presented. The analysis technique combines the finite element discretization through the thickness with wave form representation along the plate in order to calculate the dispersive modes of propagation in the plate. To study scattering of these waves by a matrix crack that grows into delaminations, a hybrid finite element representation of the field near the crack and the modal representation of the scattered exterior field are used. Results are presented showing the dependence of the reflection and transmission coefficients on the size of the crack with delamination which can be used to size the defect using ultrasonic techniques.

  11. Method for reinforcing threads in multilayer composite tubes and cylindrical structures

    SciTech Connect

    Romanoski, G.R.; Burchell, T.D.

    1996-04-01

    Multilayer techniques such as: tape wrapping, braiding, and filament winding represent versatile and economical routes for fabricating composite tubes and cylindrical structures. However, multilayer architectures lack the radial reinforcement required to retain threads when the desired means of connection or closure is a threaded joint. This issue was addressed in the development of a filament wound, carbon-carbon composite impact shell for the NASA radioisotope thermoelectric generator. The problem of poor thread shear strength was solved by incorporating a number of radial elements of triangular geometry around the circumference of the thread for the full length of thread engagement. The radial elements significantly increased the shear strength of the threaded joint by transmitting the applied force to the balance of composite structure. This approach is also applicable to ceramic composites.

  12. Fabrication and characterization of nanometric SiOx/SiOy multilayer structures obtained by LPCVD

    NASA Astrophysics Data System (ADS)

    Román-López, S.; Aceves-Mijares, M.; Carrillo-López, J.; Pedraza-Chávez, J.

    2014-05-01

    This work presents the fabrication of nanometric multilayer structures and their characterization by Atomic Force Microscopy, Photoluminescence and Fourier Transform Infra Red spectroscopy. The structures were deposited by Low Pressure Chemical Vapor Deposition (LPCVD). Three types of multilayer structure were fabricated. After the deposition some samples were annealed in N2 ambient for three hours. It was found that the structures keep the characteristics of each layer.

  13. Fabrication and characterization of nanometric SiOx/SiOy multilayer structures obtained by LPCVD

    SciTech Connect

    Román-López, S.; Aceves-Mijares, M.; Pedraza-Chávez, J.; Carrillo-López, J.

    2014-05-15

    This work presents the fabrication of nanometric multilayer structures and their characterization by Atomic Force Microscopy, Photoluminescence and Fourier Transform Infra Red spectroscopy. The structures were deposited by Low Pressure Chemical Vapor Deposition (LPCVD). Three types of multilayer structure were fabricated. After the deposition some samples were annealed in N{sub 2} ambient for three hours. It was found that the structures keep the characteristics of each layer.

  14. Fabrication, characterization, and biological assessment of multilayer laminin γ2 DNA coatings on titanium surfaces

    NASA Astrophysics Data System (ADS)

    Yang, Guoli; Zhang, Jing; Dong, Wenjing; Liu, Li; Shi, Jue; Wang, Huiming

    2016-03-01

    The purpose of this work was to fabricate a multilayer laminin γ2 DNA coating on a titanium surface and evaluate its biological properties. A multilayer laminin γ2 DNA coating was fabricated on titanium using a layer-by-layer assembly technique. The rate of coating degradation was evaluated by detecting the amount of cDNA remaining. Surface analysis using X-ray photoelectron spectroscopy, atomic force microscopy, and surface contact angle measurements revealed the multilayer structure to consist of cationic lipid and confirmed that a laminin γ2 DNA layer could be fabricated on titanium via the layer-by-layer assembly process. The transfection efficiency was highest for five layers in the multilayer structure. HEK293 cells cultured on the multilayer films displayed significantly higher adhesion activity than the control group. The expression of laminin γ2 and the co-localization of integrin β4 and plectin were more obvious in HN4 cells cultured on the multilayer laminin γ2 DNA coating, while weak immunoreactivities were observed in the control group. We concluded that the DNA-loaded multilayer provided a surface with good biocompatibility and that the multilayer laminin γ2 DNA coating might be effective in improving cell adhesion and the formation of hemidesmosomes on titanium surfaces.

  15. Fabrication, characterization, and biological assessment of multilayer laminin γ2 DNA coatings on titanium surfaces

    PubMed Central

    Yang, Guoli; Zhang, Jing; Dong, Wenjing; Liu, Li; Shi, Jue; Wang, Huiming

    2016-01-01

    The purpose of this work was to fabricate a multilayer laminin γ2 DNA coating on a titanium surface and evaluate its biological properties. A multilayer laminin γ2 DNA coating was fabricated on titanium using a layer-by-layer assembly technique. The rate of coating degradation was evaluated by detecting the amount of cDNA remaining. Surface analysis using X-ray photoelectron spectroscopy, atomic force microscopy, and surface contact angle measurements revealed the multilayer structure to consist of cationic lipid and confirmed that a laminin γ2 DNA layer could be fabricated on titanium via the layer-by-layer assembly process. The transfection efficiency was highest for five layers in the multilayer structure. HEK293 cells cultured on the multilayer films displayed significantly higher adhesion activity than the control group. The expression of laminin γ2 and the co-localization of integrin β4 and plectin were more obvious in HN4 cells cultured on the multilayer laminin γ2 DNA coating, while weak immunoreactivities were observed in the control group. We concluded that the DNA-loaded multilayer provided a surface with good biocompatibility and that the multilayer laminin γ2 DNA coating might be effective in improving cell adhesion and the formation of hemidesmosomes on titanium surfaces. PMID:26996815

  16. Multi-layered culture of human skin fibroblasts and keratinocytes through three-dimensional freeform fabrication.

    PubMed

    Lee, Wonhye; Debasitis, Jason Cushing; Lee, Vivian Kim; Lee, Jong-Hwan; Fischer, Krisztina; Edminster, Karl; Park, Je-Kyun; Yoo, Seung-Schik

    2009-03-01

    We present a method to create multi-layered engineered tissue composites consisting of human skin fibroblasts and keratinocytes which mimic skin layers. Three-dimensional (3D) freeform fabrication (FF) technique, based on direct cell dispensing, was implemented using a robotic platform that prints collagen hydrogel precursor, fibroblasts and keratinocytes. A printed layer of cell-containing collagen was crosslinked by coating the layer with nebulized aqueous sodium bicarbonate. The process was repeated in layer-by-layer fashion on a planar tissue culture dish, resulting in two distinct cell layers of inner fibroblasts and outer keratinocytes. In order to demonstrate the ability to print and culture multi-layered cell-hydrogel composites on a non-planar surface for potential applications including skin wound repair, the technique was tested on a poly(dimethylsiloxane) (PDMS) mold with 3D surface contours as a target substrate. Highly viable proliferation of each cell layer was observed on both planar and non-planar surfaces. Our results suggest that organotypic skin tissue culture is feasible using on-demand cell printing technique with future potential application in creating skin grafts tailored for wound shape or artificial tissue assay for disease modeling and drug testing. PMID:19108884

  17. 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.

  18. Formation of intermetallics at the interface of explosively welded Ni-Al multilayered composites during annealing

    NASA Astrophysics Data System (ADS)

    Ogneva, T. S.; Lazurenko, D. V.; Bataev, I. A.; Mali, V. I.; Esikov, M. A.; Bataev, A. A.

    2016-04-01

    The Ni-Al multilayer composite was fabricated using explosive welding. The zones of mixing of Ni and Al are observed at the composite interfaces after the welding. The composition of these zones is inhomogeneous. Continuous homogeneous intermetallic layers are formed at the interface after heat treatment at 620 °C during 5 h These intermetallic layers consist of NiAl3 and Ni2Al3 phases. The presence of mixed zones significantly accelerates the growth rate of intermetallic phases at the initial stages of heating.

  19. Doped SnO₂ transparent conductive multilayer thin films explored by continuous composition spread.

    PubMed

    Lee, Jin Ju; Ha, Jong-Yoon; Choi, Won-Kook; Cho, Yong Soo; Choi, Ji-Won

    2015-04-13

    Mn-doped SnO₂ thin films were fabricated by a continuous composition spread (CCS) method on a glass substrate at room temperature to find optimized compositions. The fabricated materials were found to have a lower resistivity than pure SnO₂ thin films because of oxygen vacancies generated by Mn doping. As Mn content was increased, resistivity was found to decrease for limited doping concentrations. The minimum thin film resistivity was 0.29 Ω-cm for a composition of 2.59 wt % Mn-doped SnO₂. The Sn-O vibrational stretching frequency in FT-IR showed a blue shift, consistent with oxygen deficiency. Mn-doped SnO₂/Ag/Mn-doped SnO₂ multilayer structures were fabricated using this optimized composition deposited by an on-axis radio frequency (RF) sputter. The multilayer transparent conducting oxide film had a resistivity of 7.35 × 10⁻⁵ Ω-cm and an average transmittance above 86% in the 550 nm wavelength region. PMID:25761303

  20. Space fabrication demonstration system composite beam cap fabricator

    NASA Technical Reports Server (NTRS)

    1982-01-01

    A detailed design for a prototype, composite beam cap fabricator was established. Inputs to this design included functional tests and system operating requirements. All required materials were procured, detail parts were fabricated, and one composite beam cap forming machine was assembled. The machine was demonstrated as a stand-alone system. Two 12-foot-long beam cap members were fabricated from laminates graphite/polysulfane or an equivalent material. One of these members, which as structurally tested in axial compression, failed at 490 pounds.

  1. Design, Fabrication and Characterization of Multilayered Chiral Metamaterials in Visible Frequency

    NASA Astrophysics Data System (ADS)

    Hung, Jenny

    In this thesis I report the design and fabrication of well aligned repeatable multilayered gold and silver chiral metamaterials of high uniformity in the 100nm scale which show significant circular dichroism in the visible range. Two layered Dolmen structure, two layered 3-4-5 right-angled-triangle structure and three layered 'V' structure are successfully fabricated, allowing possible applications in wave-plates and circular polarizers. These samples are produced by an e-beam direct write technique with a precise multi-layer alignment control and a lift-off process. The experimental results are well matched with simulations using a finite-integration technique from CST microwave studio. None of the structures show circular dichroism upon first layer fabrication due to the achiral property of single layer, except for the single layer 3-4-5 right-angled-triangle structure which processes 2-D chirality. All the multilayered structures exhibit circular dichroism showing qualitatively the same shape upon opposite incident direction because of the handedness of structures; and with deviations due to the presence of the substrate and buffer layers. For the 'V' structure within the first three layers the CD increases with number of layers, unveiling the importance between 3-D chirality and optical activity. The mastering of alignment technique is important for successful fabrication of multilayered optical metamaterials. This project achieves precise multi-layer alignment control which is difficult and challenging.

  2. Fabrication and characterization of ultra-high resolution multilayer-coated blazed gratings

    SciTech Connect

    Voronov,, Dmitriy; Anderson, Erik; Cambie, Rossana; Dhuey, Scott; Gullikson, Eric; Salmassi, Farhad; Yashchuk, Tony; Padmore, Howard

    2011-07-26

    Multilayer coated blazed gratings with high groove density are the most promising candidate for ultra-high resolution soft x-ray spectroscopy. They combine the ability of blazed gratings to concentrate almost all diffraction energy in a desired high diffraction order with high reflectance soft x-ray multilayers. However in order to realize this potential, the grating fabrication process should provide a near perfect groove profile with an extremely smooth surface of the blazed facets. Here we report on successful fabrication and testing of ultra-dense saw-tooth substrates with 5,000 and 10,000 lines/mm.

  3. Fabrication of thermoelectric wire-matrix composites using electrodeposition

    NASA Astrophysics Data System (ADS)

    Behnke, Joseph Frederick

    Thermoelectric materials have potential applications in a wide range of heating and cooling systems. Thermoelectric coolers, for example, are small, lightweight, and silent. They have no moving parts or fluids. What hinders a broader use of thermoelectric materials is their inefficiency when compared to compressor based systems. Theoretical studies have shown that there is a possible enhancement in thermoelectric properties through quantum confinement of the material. Recent studies have attempted to show this enhancement through the fabrication of multilayers, quantum wires and coupled quantum dots. In this study, the fabrication of thermoelectric wire-matrix composites is attempted. Porous anodic aluminum oxide was chosen as the matrix material because of its high porosity, its uniform pore diameter, its low thermal conductivity, and its compatibility with current thermoelectric device structures. CoSb 3 was chosen as the wire material because of its potential to show an enhancement in thermoelectric properties above bulk values at diameters greater than other commonly used thermoelectric materials. Electrodeposition was chosen as the method of fabrication, as it best allowed for infiltration of wire material into the matrix. It was found, however, that cobalt and antimony could not be electrodeposited into the porous matrix from the same bath. Therefore a two bath, multilayer approach was used to fabricate wires, using a post anneal to form the CoSb3 phase. The formation of CoSb3 was demonstrated by depositing alternating layers of cobalt from a CoS0 47H2O bath and antimony from an Sb2O3 bath. Both baths were aqueous and contained a supporting electrolyte of citric acid and potassium citrate. Depositing the antimony layer for 22 times the duration of the cobalt deposition gave the correct stoichiometry in the multilayers. To form CoSb3, the multilayers were annealed in an antimony ambient at temperatures greater than 575°C. The post annealing was found to

  4. Method of making multilayered titanium ceramic composites

    DOEpatents

    Fisher, II, George T.; Hansen, Jeffrey S.; Oden, Laurance L.; Turner, Paul C.; Ochs, Thomas L.

    1998-01-01

    A method making a titanium ceramic composite involves forming a hot pressed powder body having a microstructure comprising at least one titanium metal or alloy layer and at least one ceramic particulate reinforced titanium metal or alloy layer and hot forging the hot pressed body follwed by hot rolling to substantially reduce a thickness dimension and substantially increase a lateral dimension thereof to form a composite plate or sheet that retains in the microstructure at least one titanium based layer and at least one ceramic reinforced titanium based layer in the thickness direction of the composite plate or sheet.

  5. Method of making multilayered titanium ceramic composites

    DOEpatents

    Fisher, G.T. II; Hansen, J.S.; Oden, L.L.; Turner, P.C.; Ochs, T.L.

    1998-08-25

    A method making a titanium ceramic composite involves forming a hot pressed powder body having a microstructure comprising at least one titanium metal or alloy layer and at least one ceramic particulate reinforced titanium metal or alloy layer and hot forging the hot pressed body followed by hot rolling to substantially reduce a thickness dimension and substantially increase a lateral dimension thereof to form a composite plate or sheet that retains in the microstructure at least one titanium based layer and at least one ceramic reinforced titanium based layer in the thickness direction of the composite plate or sheet. 3 figs.

  6. Method of making multilayered titanium ceramic composites

    DOEpatents

    Fisher, George T., II; Hansen; Jeffrey S.; Oden; Laurance L.; Turner; Paul C.; Ochs; Thomas L.

    1998-08-25

    A method making a titanium ceramic composite involves forming a hot pressed powder body having a microstructure comprising at least one titanium metal or alloy layer and at least one ceramic particulate reinforced titanium metal or alloy layer and hot forging the hot pressed body follwed by hot rolling to substantially reduce a thickness dimension and substantially increase a lateral dimension thereof to form a composite plate or sheet that retains in the microstructure at least one titanium based layer and at least one ceramic reinforced titanium based layer in the thickness direction of the composite plate or sheet.

  7. Fabrication of Au/Ni Multilayered Nanowires by Electrochemical Deposition

    NASA Astrophysics Data System (ADS)

    Saidin, N. U.; Kok, K. Y.; Ng, I. K.; Ilias, S. H.

    2013-04-01

    Electrochemical deposition of Au/Ni multilayered nanowires using template-assisted growth technique from electrolyte containing nickel chloride and gold solution was studied in details. 60 μm-thick anodized aluminum oxide (AAO) with pore diameter of 200 nm was used as the template. Chronopotentiometry experiments were first carried out to determine the deposition conditions and the growth rate of individual Au and Ni layers. Scanning electron microscopy results revealed that the pore channels of AAO were completely filled with Au/Ni multisegmented nanowires. By selectively removing the Ni segments in the multilayered nanowires, high-yield of pure gold nanorods were obtained. Detailed studies on the nanostructures obtained were carried out using various microscopy and probe-based techniques for structural, morphological and chemical characterizations.

  8. Modifying of Cotton Fabric Surface with Nano-ZnO Multilayer Films by Layer-by-Layer Deposition Method.

    PubMed

    Uğur, Sule S; Sarıışık, Merih; Aktaş, A Hakan; Uçar, M Ciğdem; Erden, Emre

    2010-01-01

    ZnO nanoparticle-based multilayer nanocomposite films were fabricated on cationized woven cotton fabrics via layer-by-layer molecular self-assembly technique. For cationic surface charge, cotton fabrics were pretreated with 2,3-epoxypropyltrimethylammonium chloride (EP3MAC) by pad-batch method. XPS and SEM were used to examine the deposited nano-ZnO multilayer films on the cotton fabrics. The nano-ZnO films deposited on cotton fabrics exhibited excellent antimicrobial activity against Staphylococcus aureus bacteria. The results also showed that the coated fabrics with nano-ZnO multilayer films enhanced the protection of cotton fabrics from UV radiation. Physical tests (tensile strength of weft and warp yarns, air permeability and whiteness values) were performed on the fabrics before and after the treatment with ZnO nanoparticles to evaluate the effect of layer-by-layer (LbL) process on cotton fabrics properties. PMID:20596450

  9. Modifying of Cotton Fabric Surface with Nano-ZnO Multilayer Films by Layer-by-Layer Deposition Method

    PubMed Central

    2010-01-01

    ZnO nanoparticle–based multilayer nanocomposite films were fabricated on cationized woven cotton fabrics via layer-by-layer molecular self-assembly technique. For cationic surface charge, cotton fabrics were pretreated with 2,3-epoxypropyltrimethylammonium chloride (EP3MAC) by pad-batch method. XPS and SEM were used to examine the deposited nano-ZnO multilayer films on the cotton fabrics. The nano-ZnO films deposited on cotton fabrics exhibited excellent antimicrobial activity against Staphylococcus aureus bacteria. The results also showed that the coated fabrics with nano-ZnO multilayer films enhanced the protection of cotton fabrics from UV radiation. Physical tests (tensile strength of weft and warp yarns, air permeability and whiteness values) were performed on the fabrics before and after the treatment with ZnO nanoparticles to evaluate the effect of layer-by-layer (LbL) process on cotton fabrics properties. PMID:20596450

  10. Composite fabrication via resin transfer molding technology

    SciTech Connect

    Jamison, G.M.; Domeier, L.A.

    1996-04-01

    The IMPReS (Integrated Modeling and Processing of Resin-based Structures) Program was funded in FY95 to consolidate, evaluate and enhance Sandia`s capabilities in the design and fabrication of composite structures. A key driver of this and related programs was the need for more agile product development processes and for model based design and fabrication tools across all of Sandia`s material technologies. A team of polymer, composite and modeling personnel was assembled to benchmark Sandia`s existing expertise in this area relative to industrial and academic programs and to initiate the tasks required to meet Sandia`s future needs. RTM (Resin Transfer Molding) was selected as the focus composite fabrication technology due to its versatility and growing use in industry. Modeling efforts focused on the prediction of composite mechanical properties and failure/damage mechanisms and also on the uncured resin flow processes typical of RTM. Appropriate molds and test composites were fabricated and model validation studies begun. This report summarizes and archives the modeling and fabrication studies carried out under IMPReS and evaluates the status of composite technology within Sandia. It should provide a complete and convenient baseline for future composite technology efforts within Sandia.

  11. Investigation of fatigue strength of multilayer advanced fiber composites

    NASA Technical Reports Server (NTRS)

    Thornton, H. R.; Kozik, T. J.

    1974-01-01

    The analytical characterization of a multilayer fiber composite plate (without hole) was accomplished for both static and dynamic loading conditions using the finite difference technique. Thornel 300/5208 composites with and without holes were subjected to static and tensile fatigue testing. Five (5) fiber orientations were submitted to test. Tensile fatigue testing also included three (3) loading conditions and two (2) frequencies. The low-cycle test specimens demonstrated a shorter tensile fatigue life than the high-cycle test specimens. Failure surfaces demonstrated effect of testing conditions. Secondary failure mechanisms, such as: delamination, fiber breakage, and edge fiber delamination were present. Longitudinal delamination between plies also occurred in these specimens.

  12. Mechanical Behavior of Cu/Al multilayers fabricated by Accumulative Roll-Bonding (ARB) processing

    NASA Astrophysics Data System (ADS)

    Zhang, Qiwei

    For many years, there have been long-standing interests in studying multilayer metals. And many kinds of multilayers are fabricated via a variety of methods. Recently, in an effort to obtain ultrafine grains, a novel technique, namely, accumulative roll-bonding (ARB) is created, which is a kind of severe plastic deformation (SPD) process [1]. Via this technique extremely high strain can be obtained when metal materials are processed; and the properties of original metals can also be largely changed. However, ARB process is rarely applied to multilayer fabrication, especially the fabrication of multilayer bimetals. This thesis focuses on how to obtain Al/Cu multilayers via ARB process, and also examines the microstructure evolution with the increasing number of layers, and the metal properties of the obtained multilayers. This thesis first reviews the development and mechanism of rolling, one of the most important metal forming processes, and the application of rolling in metal fabrication in recent years. Then the formation and the development of ARB process are introduced, followed by current studies on ARB process. Among all the methods of fabricating multilayers, ARB process features high efficiency and continuous production of sheet materials, etc., because it is based on the rolling principle. This thesis examines a mass of unique metal properties and the microstructure of the products that experienced ARB process. In this research, a great numbers of conditions for the roll-bonding of aluminum and copper sheets were studied. Besides, aluminum and copper sheets were rolled to 1.1 mm, 0.8 mm, 0.58 mm and 0.5 mm thick as initial samples. Then the Al/Cu multilayer sheets experienced ARB process for up to 10 cycles at most, at various heat treatment temperatures under various annealing conditions, with various reductions in thickness per cycles and different thickness ratio of aluminum and copper layers. Altogether 11 groups were obtained. In this thesis, the

  13. Temperature responsive behavior of polymer brush/polyelectrolyte multilayer composites.

    PubMed

    Micciulla, Samantha; Soltwedel, Olaf; Löhmann, Oliver; von Klitzing, Regine

    2016-01-28

    The complex interaction of polyelectrolyte multilayers (PEMs) physisorbed onto end-grafted polymer brushes with focus on the temperature-responsive behavior of the system is addressed in this work. The investigated brush/multilayer composite consists of a poly(styrene sulfonate)/poly(diallyldimethylammonium chloride) (PSS/PDADMAC) multilayer deposited onto the poly(N-isopropylacrylamide-b-dimethylaminoethyl methacrylate) P(NIPAM-b-DMAEMA) brush. Ellipsometry and neutron reflectometry were used to monitor the brush collapse with the thickness decrease as a function of temperature and the change in the monomer distribution perpendicular to the substrate at temperatures below, across and above the phase transition, respectively. It was found that the adsorption of PEMs onto polymer brushes had a hydrophobization effect on PDMAEMA, inducing the shift of its phase transition to lower temperatures, but without suppressing its temperature-responsiveness. Moreover, the diffusion of the free polyelectrolyte chains inside the charged brush was proved by comparing the neutron scattering length density profile of pure and the corresponding PEM-capped brushes, eased by the enhanced contrast between hydrogenated brushes and deuterated PSS chains. The results presented herein demonstrate the possibility of combining a temperature-responsive brush with polyelectrolyte multilayers without quenching the responsive behavior, even though significant interpolyelectrolyte interactions are present. This is of importance for the design of multicompartment coatings, where the brush can be used as a reservoir for the controlled release of substances and the multilayer on the top as a membrane to control the diffusion in/out by applying different stimuli. PMID:26612742

  14. Nondestructive characterization of woven fabric ceramic composites

    SciTech Connect

    Hsu, D.K.; Saini, V.; Liaw, P.K.; Yu, N.; Miriyala, N.; McHargue, C.J.; Snead, L.L.; Lowden, R.A.

    1995-10-01

    Woven fabric ceramic composites fabricated by the chemical vapor infiltration method are susceptible to high void content and inhomogeneity. The condition of such materials may be characterized nondestructively with ultrasonic methods. In this work, longitudinal and shear waves were used in the quantitative determination of elastic constants of Nicalon{trademark}/SiC composites as a function of volume percent of porosity. Elastic stiffness constants were obtained for both the in-plane and out-of-plane directions with respect to fiber fabric. The effect of porosity on the modulus of woven fabric composites was also modeled and compared to the measured results. Scan images based on the amplitude and time-of-flight of radio frequency (RF) ultrasonic pulses were used for evaluating the material homogeneity for the purpose of optimizing the manufacturing process and for correlation with the mechanical testing results.

  15. Free form fabrication of thermoplastic composites

    SciTech Connect

    Kaufman, S.G.; Spletzer, B.L.; Guess, T.R.

    1998-02-01

    This report describes the results of composites fabrication research sponsored by the Laboratory Directed Research and Development (LDRD) program at Sandia National Laboratories. They have developed, prototyped, and demonstrated the feasibility of a novel robotic technique for rapid fabrication of composite structures. Its chief innovation is that, unlike all other available fabrication methods, it does not require a mold. Instead, the structure is built patch by patch, using a rapidly reconfigurable forming surface, and a robot to position the evolving part. Both of these components are programmable, so only the control software needs to be changed to produce a new shape. Hence it should be possible to automatically program the system to produce a shape directly from an electronic model of it. It is therefore likely that the method will enable faster and less expensive fabrication of composites.

  16. Optimization of multilayered composite pressure vessels using exact elasticity solution

    SciTech Connect

    Adali, S.; Verijenko, V.E.; Tabakov, P.Y.; Walker, M.

    1995-11-01

    An approach for the optimal design of thick laminated cylindrical pressure vessels is given. The maximum burst pressure is computed using an exact elasticity solution and subject to the Tsai-Wu failure criterion. The design method is based on an accurate 3-D stress analysis. Exact elasticity solutions are obtained using the stress function approach where the radial, circumferential and shear stresses are determined taking the closed ends of the cylindrical shell into account. Design optimization of multilayered composite pressure vessels are based on the use of robust multidimensional methods which give fast convergence. Two methods are used to determine the optimum ply angles, namely, iterative and gradient methods. Numerical results are given for optimum fiber orientation of each layer for thick and thin-walled multilayered pressure vessels.

  17. Fabrication and characterization of a new high density Sc/Si multilayer sliced grating

    NASA Astrophysics Data System (ADS)

    Voronov, Dmitriy L.; Cambie, Rossana; Gullikson, Eric M.; Yashchuk, Valeriy V.; Padmore, Howard A.; Pershin, Yuri P.; Ponomarenko, Alexander G.; Kondratenko, Valeriy V.

    2008-08-01

    State of the art soft x-ray spectroscopy techniques like Resonant Inelastic X-ray Scattering (RIXS) require diffraction gratings which can provide extremely high spectral resolution of 105-106. This problem may be addressed with a sliced multilayer grating with an ultra-high groove density (up to 50,000 mm-1) proposed in the recent publication [Voronov, D. L., et al., Proc. SPIE 6705, 67050E (2007)]. It has been suggested to fabricate such a grating by deposition of a soft x-ray multilayer on a substrate which is a blazed saw-tooth grating (echellette) with low groove density. Subsequent polishing applied to the coated grating removes part of the coating and forms an oblique-cut multiline structure that is a sliced multilayer grating. The resulting grating has a short-scale periodicity of lines (bilayers), which is defined by the multilayer period and the oblique-cut angle. We fabricated and tested a Sc/Si multilayer sliced grating suitable for EUV applications, which is a first prototype based on the suggested technique. In order to fabricate an echellette substrate, we used anisotropic KOH etching of a Si wafer. The etching regime was optimized to obtain smooth and flat echellette facets. A Sc/Si multilayer was deposited by dc-magnetron sputtering, and after that it was mechanically polished using a number of diamond pastes. The resulting sliced grating prototype with ~270 nm line period has demonstrated a dispersive ability in the 41-49 nm photon wavelength range with a diffraction efficiency of ~7% for the optimized 38th order assigned to the echellette grating of 10 μm period.

  18. Fabrication and characterization of a new high density Sc/Si multilayer sliced grating

    SciTech Connect

    Advanced Light Source; Voronov, Dmitriy L.; Cambie, Rossana; Gullikson, Eric; Yashchuk, Valeriy; Padmore, Howard; Pershin, Yuri; Ponomarenko, Alexander; Kondratenko, Valeriy

    2008-07-21

    State of the art soft x-ray spectroscopy techniques like Resonant Inelastic X-ray Scattering (RIXS) require diffraction gratings which can provide extremely high spectral resolution of 105-106. This problem may be addressed with a sliced multilayer grating with an ultra-high groove density (up to 50,000 mm-1) proposed in the recent publication [Voronov, D. L., Cambie, R., Feshchenko, R. M., Gullikson, E., Padmore, H. A., Vinogradov, A. V., Yashchuk, V. V., Proc. SPIE 6705, 67050E (2007)]. It has been suggested to fabricate such a grating by deposition of a soft x-ray multilayer on a substrate which is a blazed saw-tooth grating (echellette) with low groove density. Subsequent polishing applied to the coated grating removes part of the coating and forms an oblique-cut multiline structure that is a sliced multilayer grating. The resulting grating has a short-scale periodicity of lines (bilayers), which is defined by the multilayer period and the oblique-cut angle. We fabricated and tested a Sc/Si multilayer sliced grating suitable for EUV applications, which is a first prototype based on the suggested technique. In order to fabricate an echellette substrate, we used anisotropic KOH etching of a Si wafer. The etching regime was optimized to obtain smooth and flat echellette facets. A Sc/Si multilayer was deposited by dc-magnetron sputtering, and after that it was mechanically polished using a number of diamond pastes. The resulting sliced grating prototype with ~;;270 nm line period has demonstrated a dispersive ability in the 41-49 nm photon wavelength range with a diffraction efficiency of ~;;7percent for the optimized 38th order assigned to the echellette grating of 10 mu m period.

  19. Thermal Performance of a Customized Multilayer Insulation (MLI). Design and Fabrication of Test Facility Hardware

    NASA Technical Reports Server (NTRS)

    Leonhard, K. E.

    1975-01-01

    The design, fabrication, and assembly of hardware for testing the performance of a customized multilayer insulation are discussed. System components described include the thermal payload simulator, the modified cryoshroud, and a tank back pressure control device designed to maintain a constant liquid boiling point during the thermal evaluation of the multilayer insulation. The thermal payload simulator will provide a constant temperature surface in the range of 20.5 to 417K (37 to 750R) for the insulated tank to view. The cryoshroud was modified to establish a low temperature black body cavity while limiting liquid hydrogen usage to a minimum feasible rate.

  20. Numerical simulation of multi-layered textile composite reinforcement forming

    NASA Astrophysics Data System (ADS)

    Wang, P.; Hamila, N.; Boisse, P.

    2011-05-01

    One important perspective in aeronautics is to produce large, thick or/and complex structural composite parts. The forming stage presents an important role during the whole manufacturing process, especially for LCM processes (Liquid Composites Moulding) or CFRTP (Continuous Fibre Reinforcements and Thermoplastic resin). Numerical simulations corresponding to multi-layered composite forming allow the prediction for a successful process to produce the thick parts, and importantly, the positions of the fibres after forming to be known. This paper details a set of simulation examples carried out by using a semi-discrete shell finite element made up of unit woven cells. The internal virtual work is applied on all woven cells of the element taking into account tensions, in-plane shear and bending effects. As one key problem, the contact behaviours of tool/ply and ply/ply are described in the numerical model. The simulation results not only improve our understanding of the multi-layered composite forming process but also point out the importance of the fibre orientation and inter-ply friction during formability.

  1. Numerical simulation of multi-layered textile composite reinforcement forming

    SciTech Connect

    Wang, P.; Hamila, N.; Boisse, P.

    2011-05-04

    One important perspective in aeronautics is to produce large, thick or/and complex structural composite parts. The forming stage presents an important role during the whole manufacturing process, especially for LCM processes (Liquid Composites Moulding) or CFRTP (Continuous Fibre Reinforcements and Thermoplastic resin). Numerical simulations corresponding to multi-layered composite forming allow the prediction for a successful process to produce the thick parts, and importantly, the positions of the fibres after forming to be known. This paper details a set of simulation examples carried out by using a semi-discrete shell finite element made up of unit woven cells. The internal virtual work is applied on all woven cells of the element taking into account tensions, in-plane shear and bending effects. As one key problem, the contact behaviours of tool/ply and ply/ply are described in the numerical model. The simulation results not only improve our understanding of the multi-layered composite forming process but also point out the importance of the fibre orientation and inter-ply friction during formability.

  2. Fabrication and characterization of novel multilayered structures by stereocomplexion of poly(D-lactic acid)/poly(L-lactic acid) and self-assembly of polyelectrolytes.

    PubMed

    Dellacasa, Elena; Zhao, Li; Yang, Gesheng; Pastorino, Laura; Sukhorukov, Gleb B

    2016-01-01

    The enantiomers poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) were alternately adsorbed directly on calcium carbonate (CaCO3) templates and on poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) multilayer precursors in order to fabricate a novel layer-by-layer (LBL) assembly. A single layer of poly(L-lysine) (PLL) was used as a linker between the (PDLA/PLLA) n stereocomplex and the cores with and without the polymeric (PSS/PAH) n /PLL multilayer precursor (PEM). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) were used to characterize the chemical composition and molecular weight of poly(lactic acid) polymers. Both multilayer structures, with and without polymeric precursor, were firstly fabricated and characterized on planar supports. A quartz crystal microbalance (QCM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and ellipsometry were used to evaluate the thickness and mass of the multilayers. Then, hollow, spherical microcapsules were obtained by the removal of the CaCO3 sacrificial template. The chemical composition of the obtained microcapsules was confirmed by differential scanning calorimetry (DSC) and wide X-ray diffraction (WXRD) analyses. The microcapsule morphology was evaluated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. The experimental results confirm the successful fabrication of this innovative system, and its full biocompatibility makes it worthy of further characterization as a promising drug carrier for sustained release. PMID:26925356

  3. Fabrication and characterization of novel multilayered structures by stereocomplexion of poly(D-lactic acid)/poly(L-lactic acid) and self-assembly of polyelectrolytes

    PubMed Central

    Yang, Gesheng; Pastorino, Laura

    2016-01-01

    Summary The enantiomers poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) were alternately adsorbed directly on calcium carbonate (CaCO3) templates and on poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) multilayer precursors in order to fabricate a novel layer-by-layer (LBL) assembly. A single layer of poly(L-lysine) (PLL) was used as a linker between the (PDLA/PLLA)n stereocomplex and the cores with and without the polymeric (PSS/PAH)n/PLL multilayer precursor (PEM). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) were used to characterize the chemical composition and molecular weight of poly(lactic acid) polymers. Both multilayer structures, with and without polymeric precursor, were firstly fabricated and characterized on planar supports. A quartz crystal microbalance (QCM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and ellipsometry were used to evaluate the thickness and mass of the multilayers. Then, hollow, spherical microcapsules were obtained by the removal of the CaCO3 sacrificial template. The chemical composition of the obtained microcapsules was confirmed by differential scanning calorimetry (DSC) and wide X-ray diffraction (WXRD) analyses. The microcapsule morphology was evaluated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. The experimental results confirm the successful fabrication of this innovative system, and its full biocompatibility makes it worthy of further characterization as a promising drug carrier for sustained release. PMID:26925356

  4. Fabrication of multilayered thin films via spin-assembly

    DOEpatents

    Chiarelli, Peter A.; Robinson, Jeanne M.; Casson, Joanna L.; Johal, Malkiat S.; Wang, Hsing-Lin

    2007-02-20

    An process of forming multilayer thin film heterostructures is disclosed and includes applying a solution including a first water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species onto a substrate to form a first coating layer on the substrate, drying the first coating layer on the substrate, applying a solution including a second water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species onto the substrate having the first coating layer to form a second coating layer on the first coating layer wherein the second water-soluble polymer is of a different material than the first water-soluble polymer, and drying the second coating layer on the first coating layer so as to form a bilayer structure on the substrate. Optionally, one or more additional applying and drying sequences can be repeated with a water-soluble polymer from the group of polyanionic species, polycationic species and uncharged polymer species, so that a predetermined plurality of layers are built up upon the substrate.

  5. Application of low-coherence interferometry for in situ nondestructive evaluation of thin and thick multilayered transparent composites

    NASA Astrophysics Data System (ADS)

    Khomenko, Anton; Cloud, Gary Lee; Haq, Mahmoodul

    2015-12-01

    Multilayered transparent composites having laminates with polymer interlayers and backing sheets are commonly used in a wide range of applications where visibility, transparency, impact resistance, and safety are essential. Manufacturing flaws or damage during operation can seriously compromise both safety and performance. Most fabrication defects are not discernible until after the entire multilayered transparent composite assembly has been completed, and in-the-field inspection for damage is a problem not yet solved. A robust and reliable nondestructive evaluation (NDE) technique is needed to evaluate structural integrity and identify defects that result from manufacturing issues as well as in-service damage arising from extreme environmental conditions in addition to normal mechanical and thermal loads. Current optical techniques have limited applicability for NDE of such structures. This work presents a technique that employs a modified interferometer utilizing a laser diode or femtosecond fiber laser source to acquire in situ defect depth location inside a thin or thick multilayered transparent composite, respectively. The technique successfully located various defects inside examined composites. The results show great potential of the technique for defect detection, location, and identification in multilayered transparent composites.

  6. Fabrication and Characterization of SMA Hybrid Composites

    NASA Technical Reports Server (NTRS)

    Turner, Travis L.; Lach, Cynthia L.; Cano, Robert J.

    2001-01-01

    Results from an effort to fabrication shape memory alloy hybrid composite (SMAHC) test specimens and characterize the material system are presented in this study. The SMAHC specimens are conventional composite structures with an embedded SMA constituent. The fabrication and characterization work was undertaken to better understand the mechanics of the material system, address fabrication issues cited in the literature, and provide specimens for experimental validation of a recently developed thermomechanical model for SMAHC structures. Processes and hardware developed for fabrication of the SMAHC specimens are described. Fabrication of a SMA14C laminate with quasi-isotropic lamination and ribbon-type Nitinol actuators embedded in the 0' layers is presented. Beam specimens are machined from the laminate and are the focus of recent work, but the processes and hardware are readily extensible to more practical structures. Results of thermomechanical property testing on the composite matrix and Nitinol ribbon are presented. Test results from the Nitinol include stress-strain behavior, modulus versus temperature. and constrained recovery stress versus temperature and thermal cycle. Complex thermomechanical behaviors of the Nitinol and composite matrix are demonstrated, which have significant implications for modeling of SMAHC structures.

  7. Multi-layer hierarchical array fabricated with diatom frustules for highly sensitive bio-detection applications

    NASA Astrophysics Data System (ADS)

    Li, Aobo; Cai, Jun; Pan, Junfeng; Wang, Yu; Yue, Yue; Zhang, Deyuan

    2014-02-01

    Diatoms have delicate porous structures which are very beneficial in improving the absorbing ability in the bio-detection field. In this study, multi-layered hierarchical arrays were fabricated by packing Nitzschia soratensis (N. soratensis) frustules into Cosinodiscus argus (C. argus) frustules to achieve advanced sensitivity in bio-detection chips. Photolithographic patterning was used to obtain N. soratensis frustule arrays, and the floating behavior of C. argus frustules was employed to control their postures for packing N. soratensis frustule array spots. The morphology of the multi-layer C. argus-N. soratensis package array was investigated by scanning electron microscopy, demonstrating that the overall and sub-structures of the diatom frustules were retained. The signal enhancing effect of multi-layer C. argus-N. soratensis packages was demonstrated by fluorescent antibody test results. The mechanism of the enhancement was also analyzed, indicating that both complex hierarchical frustule structures and optimized posture of C. argus frustules were important for improving bio-detection sensitivities. The technique for fabricating multi-layer diatom frustules arrays is also useful for making multi-functional biochips and controllable drug delivery systems.

  8. Rapid fabrication of flight worthy composite parts

    NASA Astrophysics Data System (ADS)

    Jouin, Pierre H.; Heigl, John C.; Youtsey, Timothy L.

    A 3D surfaced-model representation of aircraft composite structural components can be used to generate machining paths in a system which reduces paperwork and errors, and enhances accuracy and speed. Illustrative cases are presented for the use of such a system in the design and production of the Longbow radar housing, the fabrication of the flight test hardware for the 'no tail-rotor' helicopter control system, and the machining of a honeycomb core structure for a composite helicopter rotor blade.

  9. Fabrication of multi-layered absorption structure for high quantum efficiency photon detectors

    SciTech Connect

    Fujii, Go; Fukuda, Daiji; Numata, Takayuki; Yoshizawa, Akio; Tsuchida, Hidemi; Fujino, Hidetoshi; Ishii, Hiroyuki; Itatani, Taro; Zama, Tatsuya; Inoue, Shuichiro

    2009-12-16

    We report on some efforts to improve a quantum efficiency of titanium-based optical superconducting transition edge sensors using the multi-layered absorption structure for maximizing photon absorption in the Ti layer. Using complex refractive index values of each film measured by a Spectroscopic Ellipsometry, we designed and optimized by a simulation code. An absorption measurement of fabricated structure was in good agreement with the design and was higher than 99% at optimized wavelength of 1550 nm.

  10. CAD for 4-step braided fabric composites

    SciTech Connect

    Pandey, R.; Hahn, H.T.

    1994-12-31

    A general framework is provided to predict thermoelastic properties of three dimensional 4-step braided fabric composites. Three key steps involved are (1) the development of a CAD model for yarn architecture, (2) the extraction of a unit cell (3) the prediction of the thermoelastic properties based on micromechanics. Main features of each step are summarized and experimental correlations are provided in the paper.

  11. WSi2/Si Multilayer Sectioning by Reactive Ion Etching for Multilayer Laue Lens Fabrication

    SciTech Connect

    Bouet, N.; Conley, R.; Biancarosaa, J.; Divanc, R.; Macrander, A. T.

    2010-08-01

    SPIE Conference paper/talk presentation: Introduction: Reactive ion etching (RIE) has been employed in a wide range of fields such as semiconductor fabrication, MEMS (microelectromechanical systems), and refractive x-ray optics with a large investment put towards the development of deep RIE. Due to the intrinsic differing chemistries related to reactivity, ion bombardment, and passivation of materials, the development of recipes for new materials or material systems can require intense effort and resources. For silicon in particular, methods have been developed to provide reliable anisotropic profiles with good dimensional control and high aspect ratios1,2,3, high etch rates, and excellent material to mask etch selectivity...

  12. Photoreactive azido-containing silica nanoparticle/polycation multilayers: durable superhydrophobic coating on cotton fabrics.

    PubMed

    Zhao, Yan; Xu, Zhiguang; Wang, Xungai; Lin, Tong

    2012-04-17

    In this study, we report the functionalization of silica nanoparticles with highly photoreactive phenyl azido groups and their utility as a negatively charged building block for layer-by-layer (LbL) electrostatic assembly to produce a stable silica nanoparticle coating. Azido-terminated silica nanoparticles were prepared by the functionalization of bare silica nanoparticles with 3-aminopropyltrimethoxysilane followed by the reaction with 4-azidobenzoic acid. The azido functionalization was confirmed by FTIR and XPS. Poly(allylamine hydrochloride) was also grafted with phenyl azido groups and used as photoreactive polycations for LbL assembly. For the photoreactive silica nanoparticle/polycation multilayers, UV irradiation can induce the covalent cross-linking within the multilayers as well as the anchoring of the multilayer film onto the organic substrate, through azido photochemical reactions including C-H insertion/abstraction reactions with surrounding molecules and dimerization of azido groups. Our results show that the stability of the silica nanoparticle/polycation multilayer film was greatly improved after UV irradiation. Combined with a fluoroalkylsilane post-treatment, the photoreactive LbL multilayers were used as a coating for superhydrophobic modification of cotton fabrics. Herein the LbL assembly method enables us to tailor the number of the coated silica nanoparticles through the assembly cycles. The superhydrophobicity of cotton fabrics was durable against acids, bases, and organic solvents, as well as repeated machine wash. Because of the unique azido photochemistry, the approach used here to anchor silica nanoparticles is applicable to almost any organic substrate. PMID:22462539

  13. Method for fabricating laminated uranium composites

    DOEpatents

    Chapman, L.R.

    1983-08-03

    The present invention is directed to a process for fabricating laminated composites of uranium or uranium alloys and at least one other metal or alloy. The laminated composites are fabricated by forming a casting of the molten uranium with the other metal or alloy which is selectively positioned in the casting and then hot-rolling the casting into a laminated plate in or around which the casting components are metallurgically bonded to one another to form the composite. The process of the present invention provides strong metallurgical bonds between the laminate components primarily since the bond disrupting surface oxides on the uranium or uranium alloy float to the surface of the casting to effectively remove the oxides from the bonding surfaces of the components.

  14. Electrical properties of polypropylene-based composites controlled by multilayered distribution of conductive particles.

    PubMed

    Gao, Wanli; Zheng, Yu; Shen, Jiabin; Guo, Shaoyun

    2015-01-28

    Materials consisting of alternating layers of pure polypropylene (PP) and carbon black filled polypropylene (PPCB) were fabricated in this work. The electrical behaviors of the multilayered composites were investigated from two directions: (1) Parallel to interfaces. The confined layer space allowed for a more compact connection between CB particles, while the conductive pathways tended to be broken up with increasing number of layers leading to a distinct enhancement of the electrical resistivity due to the separation of insulated PP layers. (2) Vertical to interfaces. The alternating assemblies of insulated and conductive layers like a parallel-plate capacitor made the electrical conductivity become frequency dependent. Following the layer multiplication process, the dielectric permittivity was significantly enhanced due to the accumulation of electrical charges at interfaces. Thus, as a microwave was incident on the dielectric medium, the interfacial polarization made the main contribution to inherent dissipation of microwave energy, so that the absorbing peak became strengthened when the material had more layers. Furthermore, the layer interfaces in the multilayered system were also effective to inhibit the propagation of cracks in the stretching process, leading to a larger elongation at the break than that of the PP/CB conventional system, which provided a potential route to fabricate electrical materials with optimal mechanical properties. PMID:25549245

  15. Design and fabrication of ultrafine piezoelectric composites.

    PubMed

    Yin, J; Lukacs, M; Harasiewicz, K A; Foster, F S

    2005-01-01

    Making fine scale (< 20 microm) piezoelectric composites for high frequency (> 50 MHz) ultrasound transducers remains challenging. Interdigital phase bonding (IPhB), described in this paper, presents a new technique developed to make piezoelectric composites at the ultrafine scale using a conventional dicing saw. Using the IPhB technique, a composite structure with a pitch that is less than the dicing saw blade thickness can be created. The approach is flexible enough to make composites of different combination of pitch and volume ratio. Using a conventional dicing saw with a 50 microm thick blade, composite with a 25 microm pitch and a volume ratio of 61 percent are fabricated. Such a composite is suitable for fabrication of ultrasonic transducers and arrays with central frequencies of up to 85 MHz. Single element transducers working at central frequencies of 50-60 MHz were made of these composites as a mean to characterize the acoustic performance. Measurement results of the transducers show that the longitudinal electromechanical coupling coefficient is greater than 0.6 and that there are no noticeable lateral resonances in the frequency range of 55-150 MHz. Design criteria for fine scale elements are also discussed based on theoretical results from finite element analysis (FEA). PMID:16003926

  16. Continuous unidirectional fiber reinforced composites: Fabrication and testing

    NASA Technical Reports Server (NTRS)

    Weber, M. D.; Spiegel, F. X.; West, Harvey A.

    1994-01-01

    The study of the anisotropic mechanical properties of an inexpensively fabricated composite with continuous unidirectional fibers and a clear matrix was investigated. A method has been developed to fabricate these composites with aluminum fibers and a polymer matrix. These composites clearly demonstrate the properties of unidirectional composites and cost less than five dollars each to fabricate.

  17. Composite multilayer insulations for thermal protection of aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.; Pitts, William C.

    1989-01-01

    Composite flexible multilayer insulation systems (MLI), consisting of alternating layers of metal foil and scrim cloth or insulation quilted together using ceramic thread, were evaluated for thermal performance and compared with a silica fibrous (baseline) insulation system. The systems studied included: (1) alternating layers of aluminoborosilicate (ABS) scrim cloth and stainless steel foil, with silica, ABS, or alumina insulation; (2) alternating layers of scrim cloth and aluminum foil, with silica or ABS insulation; (3) alternating layers of aluminum foil and silica or ABS insulation; and (4) alternating layers of aluminum-coated polyimide placed on the bottom of the silica insulation. The MLIs containing aluminum were the most efficient, measuring as little as half the backface temperature increase of the baseline system.

  18. Fabrication of tungsten wire reinforced nickel-base alloy composites

    NASA Technical Reports Server (NTRS)

    Brentnall, W. D.; Toth, I. J.

    1974-01-01

    Fabrication methods for tungsten fiber reinforced nickel-base superalloy composites were investigated. Three matrix alloys in pre-alloyed powder or rolled sheet form were evaluated in terms of fabricability into composite monotape and multi-ply forms. The utility of monotapes for fabricating more complex shapes was demonstrated. Preliminary 1093C (2000F) stress rupture tests indicated that efficient utilization of fiber strength was achieved in composites fabricated by diffusion bonding processes. The fabrication of thermal fatigue specimens is also described.

  19. High Tc superconductors - Composite wire fabrication

    NASA Astrophysics Data System (ADS)

    Jin, S.; Sherwood, R. C.; van Dover, R. B.; Tiefel, T. H.; Johnson, D. W., Jr.

    1987-07-01

    The fabrication of fine-wire, composite superconductors consisting of a high-conductivity normal metal shell, such as Ag or Cu/Ni/Au, and a superconducting core of Ba2YCu3O oxide is described. The functions of the normal metal shell and the importance of using the proper diffusion barrier metals are discussed. A resistivity-temperature curve for the composite wire Ag/Ba2YCu3O7 is examined, and the compound inside the finished wire is analyzed using X-ray diffraction. It is observed that the zero-field critical current density of the wire at 77 K is about 175 A/sq cm and the superconducting core is continuous and retains phase composition after wire drawing and heat treatment. The supplying of oxygen to the core of the long wire during heat treatments is studied. The data reveal that it is possible to process ceramic superconductors into a desirable composite wire form.

  20. Novel soft magnetic composites fabricated by electrodeposition

    NASA Astrophysics Data System (ADS)

    Yu, R. H.; Ren, L.; Basu, S.; Unruh, K. M.; Parvizi-Majidi, A.; Xiao, John Q.

    2000-05-01

    Soft magnetic composites have been fabricated by electrodepositing FeNi and FeCo onto W fibers with a diameter of 20 and 100 μm. Structural and compositional characterizations indicate that FeNi and FeCo-based composites are of fcc and bcc structure, respectively. The mechanical strengths are significantly improved depending on the volume fraction of W fibers. To further improve the mechanical properties of these composites, we have codeposited soft magnets and Al2O3 powders, resulting in an increase in Vickers hardness of more than 100%. Magnetic measurements show that as-deposited fibers are not magnetically soft. After proper thermal annealing, the samples exhibit excellent soft magnetic properties.

  1. Fabrication of graphite/polyimide composite structures.

    NASA Technical Reports Server (NTRS)

    Varlas, M.

    1972-01-01

    Selection of graphite/polyimide composite as a prime candidate for high-temperature structural applications involving long-duration temperature environments of 400 to 600 F. A variety of complex graphite/polyimide components has been fabricated, using a match-metal die approach developed for making fiber-reinforced resin composites. Parts produced include sections of a missile adapter skin flange, skin frame section, and I-beam and hat-section stringers, as well as unidirectional (0 deg) and plus or minus 45 deg oriented graphite/polyimide tubes in one-, two-, and six-inch diameters.

  2. Physical vapor deposition of multilayered lead-zirconate-titanate films for ultrasonic transducer fabrication

    NASA Astrophysics Data System (ADS)

    Kline-Schoder, Robert J.; Kynor, David B.; Jaeger, Michael D.; Winder, Alan A.; Desilets, Charles S.

    1999-06-01

    Creare is developing microfabrication techniques to manufacture low-cost, multi-dimensional ultrasonic transducer arrays with single- and multi-layer piezoelectric elements for low impedance and high sensitivity. The manufacturing approach is scaleable for fabrication of transducer arrays in the frequency range of 10 - 50 MHz in dense or sparse array configurations. Our approach employs the following processes: (1) Physical Vapor Deposition (PVD or sputtering) of high-quality, piezoelectric films using reactive sputtering of metallic targets and (2) Novel use of state-of-the-art photolithography and masking to provide the interlayer electrodes, element interconnections, and array element fabrication. To date, Creare has successfully demonstrated that piezoelectrically active thick films of PZT material can be deposited by using a reactive sputtering approach. In addition, these thick, multi-layer PZT films have been formed into high aspect ratio elements using dicing to fabricate a 12 MHz transducer. Array designs based on these films show that expected performance should meet the requirements for high resolution biomedical imaging.

  3. Nanointaglio fabrication of optical lipid multilayer diffraction gratings with applications in biosensing

    NASA Astrophysics Data System (ADS)

    Lowry, Troy Warren

    The dynamic self-organization of lipids in biological systems is a highly regulated process that enables the compartmentalization of living systems at microscopic and nanoscopic levels. Exploiting the self-organization and innate biofunctionality of lyotropic liquid crystalline phospholipids, a novel nanofabrication process called "nanointaglio" was invented in order to rapidly and scalably integrate lipid nanopatterns onto the surface. The work presented here focuses on using nanointaglio fabricated lipid diffraction micro- and nanopatterns for the development of new sensing and bioactivity studies. The lipids are patterned as diffraction gratings for sensor functionality. The lipid multilayer gratings operate as nanomechanical sensor elements that are capable of transducing molecular binding to fluid lipid multilayers into optical signals in a label free manner due to shape changes in the lipid nanostructures. To demonstrate the label free detection capabilities, lipid nanopatterns are shown to be suitable for the integration of chemically different lipid multilayer gratings into a sensor array capable of distinguishing vapors by means of an optical nose. Sensor arrays composed of six different lipid formulations are integrated onto a surface and their optical response to three different vapors (water, ethanol and acetone) in air as well as pH under water is monitored as a function of time. Principal component analysis of the array response results in distinct clustering, indicating the suitability of the arrays for distinguishing these analytes. Importantly, the nanointaglio process used is capable of producing lipid gratings out of different materials with sufficiently uniform heights for the fabrication of an optical nose. A second main application is demonstrated for the study of membrane binding proteins. Although in vitro methods for assaying the catalytic activity of individual enzymes are well established, quantitative methods for assaying the kinetics of

  4. Nanorods of Co/Pd multilayers fabricated by glancing angle deposition for advanced media

    NASA Astrophysics Data System (ADS)

    Su, Hao; Natarajarathinam, Anusha; Gupta, Subhadra

    2013-05-01

    Perpendicular anisotropy magnetic nanorods composed of Co/Pd multilayers have been successfully fabricated by glancing angle deposition (GLAD) in a planetary sputtering system. Co and Pd layer thickness, ratio, and bilayer number were optimized for both normal and GLAD depositions. Scanning electron micrographs estimated the nanorods to be about 12 nm in diameter. M-H loops showed that the coercivity for the GLAD nanorods increased from 1.3 kOe for the normally deposited continuous films to 2.9 kOe for the GLAD nanorod array, a 123% increase.

  5. Nanorods of Co/Pd multilayers fabricated by glancing angle deposition for advanced media

    SciTech Connect

    Su, Hao; Gupta, Subhadra; Natarajarathinam, Anusha

    2013-05-28

    Perpendicular anisotropy magnetic nanorods composed of Co/Pd multilayers have been successfully fabricated by glancing angle deposition (GLAD) in a planetary sputtering system. Co and Pd layer thickness, ratio, and bilayer number were optimized for both normal and GLAD depositions. Scanning electron micrographs estimated the nanorods to be about 12 nm in diameter. M-H loops showed that the coercivity for the GLAD nanorods increased from 1.3 kOe for the normally deposited continuous films to 2.9 kOe for the GLAD nanorod array, a 123% increase.

  6. Method of fabricating composite superconducting wire

    DOEpatents

    Strauss, Bruce P.; Reardon, Paul J.; Remsbottom, Robert H.

    1977-01-01

    An improvement in the method for preparing composite rods of superconducting alloy and normal metal from which multifilament composite superconducting wire is fabricated by bending longitudinally a strip of normal metal around a rod of superconductor alloy and welding the edges to form the composite rod. After the rods have preferably been provided with a hexagonal cross-sectional shape, a plurality of the rods are stacked into a normal metal extrusion can, sealed and worked to reduce the cross-sectional size and form multifilament wire. Diffusion barriers and high-electrical resistance barriers can easily be introduced into the wire by plating or otherwise coating the faces of the normal metal strip with appropriate materials.

  7. Multilayer soft lithography of perfluoropolyether based elastomer for microfluidic device fabrication.

    PubMed

    Devaraju, Naga Sai Gopi Krishna; Unger, Marc Alexander

    2011-06-01

    The compatibility of microfluidic devices with solvents and other chemicals is extremely important for many applications such as organic synthesis in microreactors and drug screening. We report the successful fabrication of microfluidic devices from a novel perfluoropolyether based polymer utilizing the Multilayer Soft Lithography™ (MSL) technique with simple, straightforward processing. The perfluorinated polymer SIFEL X-71 8115 is a highly chemically resistant elastomeric material. We demonstrate fabrication of a microfluidic device using an off-ratio bonding technique to bond multiple SIFEL layers, each patterned lithographically. The mechanical properties of the SIFEL MSL valves (including actuation pressures) are similar to PDMS MSL valves of the same geometry. Chemical compatibility tests highlight SIFEL's remarkable resistance to organic solvents, acids and alkalis. PMID:21503367

  8. Kinetic inductance as a microwave circuit design variable by multilayer fabrication

    NASA Astrophysics Data System (ADS)

    Adamyan, A. A.; de Graaf, S. E.; Kubatkin, S. E.; Danilov, A. V.

    2015-08-01

    We report on the development of a reliable NbN/Al/Nb/NbN multilayer fabrication technique for combining design elements with and without kinetic inductance in superconducting microwave circuits. As a proof-of-concept we demonstrate the application of the proposed technique to build a slow microwave propagation line matched to 50 Ω terminals. Fabrication details along with the design and measurements are discussed. At 8 GHz the presented device operates as a dc controllable full-turn phase shifter. We suggest that by exploiting the kinetic inductance as a design variable one can greatly improve operation parameters for a variety of standard microwave designs such as step-impedance filters and resonators.

  9. Fabrication of multilayer passive electric components using inkjet printing and low temperature laser processing on polymer

    NASA Astrophysics Data System (ADS)

    Ko, Seung Hwan; Chung, Jaewon; Pan, Heng; Grigoropoulos, Costas P.; Poulikakos, Dimos

    2006-02-01

    The low temperature fabrication of passive electrical components (conductor, capacitor) on the flexible polymer substrate is presented in this paper. A drop-on-demand (DOD) ink-jetting system was used to print gold nano-particles suspended in Alpha-Terpineol solvent and PVP in PGMEA solvent to fabricate passive electrical components on flexible polymer substrate. Short pulsed laser ablation enabled finer electrical components to overcome limitation of inkjet process. Continuous Argon ion laser was irradiated locally to evaporate carrier solvent as well as to sinter gold nano-particles. In addition, a self alignment technique for PVP layer was demonstrated taking advantage of the deliberate modification of surface wetting characteristics. Finally, a new selective ablation of multilayered gold nanoparticle film was demonstrated using the ablation threshold difference for sintered and non sintered gold nanoparticles.

  10. Mass fabrication and delivery of 3D multilayer μTags into living cells

    PubMed Central

    Chen, Lisa Y.; Parizi, Kokab B.; Kosuge, Hisanori; Milaninia, Kaveh M.; McConnell, Michael V.; Wong, H.-S. Philip; Poon, Ada S. Y.

    2013-01-01

    Continuous monitoring of in vivo biological processes and their evolution at the cellular level would enable major advances in our understanding of biology and disease. As a stepping stone towards chronic cellular monitoring, we demonstrate massively parallel fabrication and delivery of 3D multilayer micro-Tags (μTags) into living cells. Both 10 μm × 10 μm × 1.5 μm and 18 μm × 7 μm × 1.5 μm devices containing inductive and capacitive structures were designed and fabricated as potential passive radio-frequency identification tags. We show cellular internalization and persistence of μTags over a 5-day period. Our results represent a promising advance in technologies for studying biology and disease at the cellular level. PMID:23887586

  11. Fabrication of polyelectrolyte multilayered nano-capsules using a continuous layer-by-layer approach.

    PubMed

    Elizarova, Iuliia S; Luckham, Paul F

    2016-05-15

    The layer-by-layer approach is a highly versatile method for the fabrication of multilayered polymeric films and capsules. It has been widely investigated in research for various polyelectrolyte pairs and core template particles. However, the fabrication of nano-sized capsules at the larger scale is difficult and time consuming, due to the necessity of washing and centrifugation steps before the deposition of each polyelectrolyte layer. This results not only in a very long fabrication time, but also in the partial loss of particles during those intermediate steps. In this study, we introduced a continuous approach for the fabrication of multilayer polyelectrolyte based nano-capsules using calcium phosphate core nanoparticles and a tubular flow type reactor with the potential for synthesizing tens of milligrams of capsules per hour. Adsorption of the polyelectrolyte layer occurred in the tubing where particles and polyelectrolyte solution of choice were mixed, creating a layer of polyelectrolyte on the particles. After this, these newly surfaced-modified particles passed into the next segment of tubing, where they were mixed with a second polyelectrolyte of opposite charge. This process can be continuously repeated until the desired number of layers is achieved. One potential problem with this method concerned the presence of any excess polyelectrolyte in the tubing, so careful control of the amount of polymer added was crucial. It was found that slightly under dosing the amount of added polyelectrolyte ensured that negligible unadsorbed polyelectrolyte remained in solution. The particles created at each deposition step were stable, as they all had a zeta potential of greater than ±25mV. Furthermore the zeta potential measurements showed that charge reversal occurred at each stage. Having achieved the necessary number of polyelectrolyte layers, the calcium phosphate cores were easily removed via dissolution in either hydrochloric or acetic acid. PMID:26939072

  12. Fabrication and testing of composite ring specimens

    NASA Technical Reports Server (NTRS)

    Liber, T.; Daniel, I. M.; Labedz, R.; Niiro, T.

    1979-01-01

    The tooling and techniques used in the fabrication of composite laminate tubes of any desired ply orientation and stacking sequence are described along with techniques for cutting ring specimens under internal pressure. The method consists of laying up the tube on a central circular mandrel, and by means of internal pressure, expanding the prepreg tube against the cavity wall of an external mold tool, which forms the geometric curing envelope for the tube. Tube quality is assessed by laminate wall thickness measurement, by hoop strength measurement on rings cut from the ends of the tube, and by ultrasonic inspection.

  13. Design and fabrication of multilayer dielectric gratings for spectral beam combining

    NASA Astrophysics Data System (ADS)

    Cho, Hyun-Ju; Kim, Hyun-Tae; Lee, Yong-Soo

    2015-08-01

    Metal gratings are mostly used on low energy optics, but it has low laser damage threshold. Spectral beam combining is a method to make high power laser beam using diffraction gratings. Multilayer dielectric (MLD) high reflectance mirror is designed for high efficiency gratings using HfO2 and SiO2 for high laser damage threshold. On the top of the mirror, polarization dependent SiO2 grating structure is simulated by finite domain time division (FDTD) method at 1055nm for spectral beam combining. To estimate the far field diffraction characteristics, we first calculate near field electromagnetic wave properties at the substrate region and these are transformed to angular diffraction characteristics at about 1 meter apart from the grating. Multilayer dielectric mirror is deposited by electron beam evaporation method at the substrate temperature 250°C. Four types of high efficiency MLD gratings are selected and these are fabricated by lithography and reactive ion etching method. To fabricate the designed submicron structure, 4X stepper is used for pattern formation on the photo resistor. We use fused silica as a substrate and additional dummy silicon wafer substrates are used for grating structure confirmation using scanning electron microscope. The diffraction efficiencies are measured and these are compared with simulated results.

  14. Solution-Based Fabrication of Perovskite Multilayers and Superlattices Using Nanosheet Process

    NASA Astrophysics Data System (ADS)

    Li, Bao-Wen; Osada, Minoru; Akatsuka, Kosho; Ebina, Yasuo; Ozawa, Tadashi C.; Sasaki, Takayoshi

    2011-09-01

    We report a solution-based fabrication of perovskite multilayers and superlattices using perovskite nanosheets. Perovskite nanosheets (LaNb2O7, Ca2Nb3O10, and Sr2Nb3O10) were prepared by delaminating layered perovskites. A layer-by-layer approach using Langmuir-Blodgett deposition was effective for fabricating high-quality nanofilms of perovskite nanosheets on various substrates, such as quartz glass, Si, and SrRuO3. Structural characterizations by X-ray diffraction, transmission electron microscopy, and hard X-ray photoelectron spectroscopy revealed that these perovskite nanofilms are composed of a well-ordered lamellar structure with an atomically sharp interface. The multilayer films exhibited a stable dielectric response inherent to the perovskite nanosheet. We also found that the superlattices of (LaNb2O7/Ca2Nb3O10)5 and (Sr2Nb3O10/Ca2Nb3O10)5 possess strong interface coupling, which gives rise to enhanced dielectric constant.

  15. Advanced composites: Fabrication processes for selected resin matrix materials

    NASA Technical Reports Server (NTRS)

    Welhart, E. K.

    1976-01-01

    This design note is based on present state of the art for epoxy and polyimide matrix composite fabrication technology. Boron/epoxy and polyimide and graphite/epoxy and polyimide structural parts can be successfully fabricated. Fabrication cycles for polyimide matrix composites have been shortened to near epoxy cycle times. Nondestructive testing has proven useful in detecting defects and anomalies in composite structure elements. Fabrication methods and tooling materials are discussed along with the advantages and disadvantages of different tooling materials. Types of honeycomb core, material costs and fabrication methods are shown in table form for comparison. Fabrication limits based on tooling size, pressure capabilities and various machining operations are also discussed.

  16. Fabrication of nylon-6/carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Xu, C.; Jia, Z.; Wu, D.; Han, Q.; Meek, T.

    2006-05-01

    A new technique to fabricate nylon-6/carbon nanotube (PA6/CNT) composites is presented. The method involves a pretreatment of carbon nanotubes synthesized by catalytic pyrolysis of hydrocarbon and an improved in-situ process for mixing nanotubes with the nylon 6 matrix. A good bond between carbon nanotubes and the nylon-6 matrix is obtained. Mechanical property measurements indicate that the tensile strength of PA6/CNT composites is improved significantly while the toughness and elongation are somewhat compromised. Scanning electron microscopy (SEM) analysis of the fractured tensile specimens reveals cracking initiated at the wrapping of the CNTs PA6 layer/PA6 matrix interface rather than at the PA6/CNT interface.

  17. Composite material fabrication techniques. CRADA final report

    SciTech Connect

    Frame, B J; Paulauskas, F L; Miller, J; Parzych, W

    1996-09-30

    This report describes a low cost method of fabricating components for mockups and training simulators used in the transportation industry. This technology was developed jointly by the Oak Ridge National Laboratory (ORNL) and Metters Industries, Incorporated (MI) as part of a Cooperative Research and Development Agreement (CRADA) ORNL94-0288 sponsored by the Department of Energy (DOE) Office of Economic Impace and Diversity Minority Business Technology Transfer Consortium. The technology involves fabricating component replicas from fiberglass/epoxy composites using a resin transfer molding (RTM) process. The original components are used as masters to fabricate the molds. The molding process yields parts that duplicate the significant dimensional requirements of the original component while still parts that duplicate the significant dimensional requirements of the original component while still providing adequate strength and stiffness for use in training simulators. This technology permits MI to overcome an acute shortage in surplus military hardware available to them for use in manufacturing training simulators. In addition, the cost of the molded fiberglass components is expected to be less than that of procuring the original components from the military.

  18. Fabric geometry distortion during composites processing

    NASA Technical Reports Server (NTRS)

    Chen, Julie

    1994-01-01

    Waviness and tow misalignment are often cited as possible causes of data scatter and lower compression stiffness and strength in textile composites. Strength differences of as much as 40 percent have been seen in composites that appear to have the same basic material and structural properties -- i.e., yarn orientation, yarn size, interlacing geometry. Fabric geometry distortion has been suggested as a possible reason for this discrepancy, but little quantitative data or substantial evidence exists. The focus of this research is to contribute to the present understanding of the causes and effects of geometric distortion in textile composites. The initial part of the study was an attempt to gather qualitative information on a variety of textile structures. Existing and new samples confirmed that structures with a significant direction presence would be more susceptible to distortion due to the compaction process. Thus, uniweaves (fiber vol frac: 54-72 percent) biaxial braids (vf: 34-58 percent) demonstrated very little fabric geometry distortion. In stitched panels, only slight buckling of z-direction stitches was observed, primarily near the surface. In contrast, for structures with high compaction ratios -- e.g., large cylindrical yarns (2.5:1) orpowder towpreg (4:1) -- there were visible distortions where previously smooth and periodic undulations were transformed to abrupt changes in direction. A controlled study of the effect of forming pressure on distortion was conducted on type 162 glass plain weave fabrics. Panels (6 x 6 in) were produced via a resin infusion type setup, but with an EPON 815 epoxy resin. Pressures ranging from hand layup to 200 psi were used (vf: 34-54 percent). Photomicrographs indicated that at pressures up to 50 psi, large changes in thickness were due primarily to resin squeeze out. At higher pressures, when intimate contact was made between the layers, there was some tow flattening and in-plane shifting to optimize nesting. However

  19. Analysis of thermal stresses in composite laminates by assumed stress hybrid multilayer element

    SciTech Connect

    Wang Liangzhong; Wang Cheng )

    1993-03-01

    Based on Hellinger-Reissner principle, a hybrid multilayer element is presented in this article. This element can be used for analyzing thermoelastic stresses in composite laminates induced by nonuniform temperature distribution. The thermal loads are derived from the functional directly in the element model. Numerical results show that this multilayer element model is suitable for thermal stress analysis of laminated composite structures. 9 refs.

  20. A fabrication and characterictics of microbolometer detectors using VOx/ZnO/VOx multilayer thin film processing

    NASA Astrophysics Data System (ADS)

    Han, Myung-Soo; Kim, Dae Hyeon; Ko, Hang Ju; Shin, Jae Chul; Kim, Hyo Jin; Kim, Do Gun

    2014-06-01

    In this work, a novel fabrication method for VOx-ZnO multilayers with mixed phase of the VO2 and V2O3 through the diffusion of oxygen by annealing at low temperature is presented. A stable sandwich structure of a VOx/ZnO/VOx multilayer was deposited at room temperature, through the oxygen gas flow rate, by RF sputtering system, and the mixed phase was formed through oxygen diffusion by annealing at O2 atmosphere. The results show that the single phase like multilayer formed by this process has a high TCR of more than -2.5%/K and low resistance of about 100 kohm at room temperature. XRD results for the as-deposited VOx/ZnO/VOx multilayer.

  1. Design, Fabrication and Testing of Multilayer Coated X-Ray Optics for the Water Window Imaging X-Ray Microscope

    NASA Technical Reports Server (NTRS)

    Spencer, Dwight C.

    1996-01-01

    Hoover et. al. built and tested two imaging Schwarzschild multilayer microscopes. These instruments were constructed as prototypes for the "Water Window Imaging X-Ray Microscope," which is a doubly reflecting, multilayer x-ray microscope configured to operate within the "water window." The "water window" is the narrow region of the x-ray spectrum between the K absorption edges of oxygen (lamda = 23.3 Angstroms) and of carbon (lamda = 43.62 Angstroms), where water is relatively highly transmissive and carbon is highly absorptive. This property of these materials, thus permits the use of high resolution multilayer x-ray microscopes for producing high contrast images of carbon-based structures within the aqueous physiological environments of living cells. We report the design, fabrication and testing of multilayer optics that operate in this regime.

  2. Fabrication and characterization of reactive nanoscale multilayer systems for low-temperature bonding in microsystem technology

    NASA Astrophysics Data System (ADS)

    Boettge, Bianca; Braeuer, Joerg; Wiemer, Maik; Petzold, Matthias; Bagdahn, Joerg; Gessner, Thomas

    2010-06-01

    Reactive bonding is a still new low-temperature joining process that is based on reactive nanoscale multilayer systems. The heat required for the bonding process is generated by a self-propagating exothermic reaction within the multilayer system while the adhesive interconnect is supported by solder films. For microsystem applications, the approach is particularly useful if temperature-sensitive components and materials with high differences in coefficient of thermal expansion have to be joined. In this paper, this is successfully demonstrated for bonding a quartz strain gauge onto a stainless steel membrane and an IR-emitter onto a covar socket by using commercially available nickel/aluminum NanoFoils©. The quality of the bond interface of both demonstrators was investigated by scanning electron microscopy and the strength was determined by a tensile test. On the other hand, integrated microsystem applications beyond die attachment require patterned bond structures, e.g. to form bond frames. Thus, alternative materials were additionally considered that can be directly deposited on silicon substrates by magnetron sputtering, such as aluminum/titanium as well as titanium/amorphous silicon (Ti/a-Si) bilayer systems. The properties of these basic multilayer systems and their reaction products were characterized by differential scanning calorimetry and high-resolution electron microscopy. It is shown that specifically the Ti/a-Si system has substantial potential for direct microsystem technology integration provided the remaining open technological issues can be addressed during future research. In general, the results obtained in this study demonstrate the high potential of the reactive bonding process as a new advantageous assembly technology for the fabrication of future microsystems.

  3. MOVPE of GaSb/InGaAsSb Multilayers and Fabrication of Dual Band Photodetectors

    NASA Technical Reports Server (NTRS)

    Xiao, Ye-Gao; Bhat, Ishwara; Refaat, Tamer F.; Abedin, M. Nurul; Shao, Qing-Hui

    2005-01-01

    Metalorganic vapor phase epitaxy (MOVPE) of GaSb/InGaAsSb multilayer thin films and fabrication of bias-selectable dual band photodetectors are reported. For the dual band photodetectors the short wavelength detector, or the upper p- GaSb/n-GaSb junction photodiode, is placed optically ahead of the long wavelength one, or the lower photodiode. The latter is based on latticed-matched In0.13Ga0.87As0.11Sb0.89 with bandgap near 0.6 eV. Specifically, high quality multilayer thin films are grown sequentially from top to bottom as p+-GaSb/p-GaSb/n-GaSb/n-InGaAsSb/p-InGaAsSb/p-GaSb on undoped p-type GaSb substrate, and as n-GaSb/p-GaSb/p-InGaAsSb/n-InGaAsSb/n-GaSb on Te-doped n-type GaSb substrate respectively. The multilayer thin films are characterized by optical microscope, atomic force microscope (AFM), electron microprobe analyses etc. The photodiode mesa steps are patterned by photolithography with wet chemical etching and the front metallization is carried out by e-beam evaporation with Pd/Ge/Au/Ti/Au to give ohmic contact on both n- and p-type Sb based layer surfaces. Dark I-V measurements show typical diode behavior for both the upper and lower photodiodes. The photoresponsivity measurements indicate that both the upper and lower photodiodes can sense the infrared illumination corresponding to their cutoff wavelengths respectively, comparable with the simulation results. More work is underway to bring the long wavelength band to the medium infrared wavelength region near 4 micrometers.

  4. Method of Fabricating a Piezoelectric Composite Apparatus

    NASA Technical Reports Server (NTRS)

    Wilkie, W. Keats (Inventor); Bryant, Robert (Inventor); Fox, Robert L. (Inventor); Hellbaum, Richard F. (Inventor); High, James W. (Inventor); Jalink, Antony, Jr. (Inventor); Little, Bruce D. (Inventor); Mirick, Paul H. (Inventor)

    2003-01-01

    A method for fabricating a piezoelectric macro-fiber composite actuator comprises providing a piezoelectric material that has two sides and attaching one side upon an adhesive backing sheet. The method further comprises slicing the piezoelectric material to provide a plurality of piezoelectric fibers in juxtaposition. A conductive film is then adhesively bonded to the other side of the piezoelectric material, and the adhesive backing sheet is removed. The conductive film has first and second conductive patterns formed thereon which are electrically isolated from one another and in electrical contact with the piezoelectric material. The first and second conductive patterns of the conductive film each have a plurality of electrodes to form a pattern of interdigitated electrodes. A second film is then bonded to the other side of the piezoelectric material. The second film may have a pair of conductive patterns similar to the conductive patterns of the first film.

  5. Method of Fabricating a Composite Apparatus

    NASA Technical Reports Server (NTRS)

    Wilkie, W. Keats (Inventor); Bryant, Robert G. (Inventor); Fox, Robert L. (Inventor); Hellbaum, Richard F. (Inventor); High, James W. (Inventor); Jalink, Antony, Jr. (Inventor)

    2007-01-01

    A method for fabricating a piezoelectric macro-fiber composite actuator comprises making a piezoelectric fiber sheet by providing a plurality of wafers of piezoelectric material, bonding the wafers together with an adhesive material to from a stack of alternating layers of piezoelectric material and adhesive material, and cutting through the stack in a direction substantially parallel to the thickness of the stack and across the alternating layers of piezoelectric material and adhesive material to provide at least one piezoelectric fiber sheet having two sides comprising a plurality of piezoelectric fibers in juxtaposition to the adhesive material. The method further comprises bonding two electrically conductive films to the two sides of the piezoelectric fiber sheet. At least one conductive film has first and second conductive patterns formed thereon which are electrically isolated from one another and in electrical contact with the piezoelectric fiber sheet.

  6. Apparatus for fabricating composite ceramic members

    DOEpatents

    Roy, P.; Simpson, J.L.; Aitken, E.A.

    1975-10-28

    Methods and apparatus for fabrication of composite ceramic members having particular application for measuring oxygen activities in liquid sodium are described. The method involves the simultaneous deposition of ThO$sub 2$: 15 percent Y$sub 2$O$sub 3$ on a sintered stabilized zirconia member by decomposition of gaseous ThCl$sub 4$ and YCl$sub 3$ and by reacting with oxygen gas. Means are provided for establishing an electrical potential gradient across the zirconia member whereby oxygen ions, from a source on one side of the member portion to be coated, are migrated to the opposite side where a reaction and said decomposition and deposition are effected.

  7. Fabrication and evolution of multilayer silver nanofilms for surface-enhanced Raman scattering sensing of arsenate

    PubMed Central

    2011-01-01

    Surface-enhanced Raman scattering (SERS) has recently been investigated extensively for chemical and biomolecular sensing. Multilayer silver (Ag) nanofilms deposited on glass slides by a simple electroless deposition process have been fabricated as active substrates (Ag/GL substrates) for arsenate SERS sensing. The nanostructures and layer characteristics of the multilayer Ag films could be tuned by varying the concentrations of reactants (AgNO3/BuNH2) and reaction time. A Ag nanoparticles (AgNPs) double-layer was formed by directly reducing Ag+ ions on the glass surfaces, while a top layer (3rd-layer) of Ag dendrites was deposited on the double-layer by self-assembling AgNPs or AgNPs aggregates which had already formed in the suspension. The SERS spectra of arsenate showed that characteristic SERS bands of arsenate appear at approximately 780 and 420 cm-1, and the former possesses higher SERS intensity. By comparing the peak heights of the approximately 780 cm-1 band of the SERS spectra, the optimal Ag/GL substrate has been obtained for the most sensitive SERS sensing of arsenate. Using this optimal substrate, the limit of detection (LOD) of arsenate was determined to be approximately 5 μg·l-1. PMID:21711772

  8. COMMAND: A FORTRAN program for simplified composite analysis and design. [computerized design of multilayered composite panels

    NASA Technical Reports Server (NTRS)

    Vanderplaats, G. N.

    1976-01-01

    A FORTRAN program is presented for preliminary analysis and design of multilayered composite panels subjected to inplane loads. All plys are of the same material. The composite is assumed symmetric about the midplane, but need not be balanced. Failure criterion includes limit ply strains and lower bounds on composite inplane stiffnesses. Multiple load conditions are considered. The required input data is defined and examples are provided to aid the use in making the program operational. Average panel design times are two seconds on an IBM 360/67 computer. Results are compared with published literature. A complete FORTRAN listing of program COMAND is provided. In addition, the optimization program CONMIN is required for design.

  9. A study on various fabrication routes for preparing multilayered cubic boron nitride films and sp(3)-like boron nitride films

    NASA Astrophysics Data System (ADS)

    Wong, Sing Fai

    Cubic boron nitride (cBN) has a sp3-bonded structure which leads to excellent mechanical properties. Though cBN-rich films have been successfully fabricated by many techniques, the adhesion of the films is still unsatisfactory due to the high stresses. The maximum sustainable thickness of cBN-rich films with good adhesion is widely reported to be around 200 nm, so many practical applications of cBN coatings are hindered. In this study, we designed a series of deposition schemes in a logical sequence, in order to explore whether stress can be released, or other structural forms of BN with potential applications can be made, and to gain more fundamental understanding on the growth mechanisms of various phases observed in the films. Various fabrication processes were employed according to the following sequence: (1) A single-step process. It was showed that the maximum tolerable thickness of the cBN-rich films prepared by our system (183nm) was compatible with the result in literatures (200nm). (2) A multilayered deposition process. A thick sp2-bonded boron nitride (sP2-BN) buffer layer which was relatively deformable was added, and hence some stresses were released so as to allow a 643nm-thick, 87vol.% cBN-rich layer with acceptable adhesion to grow on top. (3) An advanced multilayer process with subsequent annealing process. A zirconium layer was pre-deposited to remove the soft buffer layer after postannealing. The interface could be strengthened as the zirconium-boride/nitride was formed. (4) Ion assist deposition at unheated condition. Composite BN films containing sp3 nanoclusters embedded in a sp2-BN matrix were fabricated. The IR technique was not sensitive enough to detect spa nanoclusters, but their presence was verified by the results of other measurements. In particular, the sp3 content can be over 30vo1.%, with a hardness 20GPa. The influences of the assist beam energy and substrate temperature on the generation of the sp3 nanoclusters were investigated

  10. Polyelectrolyte multilayer-assisted fabrication of non-periodic silicon nanocolumn substrates for cellular interface applications

    NASA Astrophysics Data System (ADS)

    Lee, Seyeong; Kim, Dongyoon; Kim, Seong-Min; Kim, Jeong-Ah; Kim, Taesoo; Kim, Dong-Yu; Yoon, Myung-Han

    2015-08-01

    Recent advances in nanostructure-based biotechnology have resulted in a growing demand for vertical nanostructure substrates with elaborate control over the nanoscale geometry and a high-throughput preparation. In this work, we report the fabrication of non-periodic vertical silicon nanocolumn substrates via polyelectrolyte multilayer-enabled randomized nanosphere lithography. Owing to layer-by-layer deposited polyelectrolyte adhesives, uniformly-separated polystyrene nanospheres were securely attached on large silicon substrates and utilized as masks for the subsequent metal-assisted silicon etching in solution. Consequently, non-periodic vertical silicon nanocolumn arrays were successfully fabricated on a wafer scale, while each nanocolumn geometric factor, such as the diameter, height, density, and spatial patterning, could be fully controlled in an independent manner. Finally, we demonstrate that our vertical silicon nanocolumn substrates support viable cell culture with minimal cell penetration and unhindered cell motility due to the blunt nanocolumn morphology. These results suggest that vertical silicon nanocolumn substrates may serve as a useful cellular interface platform for performing a statistically meaningful number of cellular experiments in the fields of biomolecular delivery, stem cell research, etc.Recent advances in nanostructure-based biotechnology have resulted in a growing demand for vertical nanostructure substrates with elaborate control over the nanoscale geometry and a high-throughput preparation. In this work, we report the fabrication of non-periodic vertical silicon nanocolumn substrates via polyelectrolyte multilayer-enabled randomized nanosphere lithography. Owing to layer-by-layer deposited polyelectrolyte adhesives, uniformly-separated polystyrene nanospheres were securely attached on large silicon substrates and utilized as masks for the subsequent metal-assisted silicon etching in solution. Consequently, non-periodic vertical

  11. Fabrication of 200 nanometer period centimeter area hard x-ray absorption gratings by multilayer deposition.

    PubMed

    Lynch, S K; Liu, C; Morgan, N Y; Xiao, X; Gomella, A A; Mazilu, D; Bennett, E E; Assoufid, L; de Carlo, F; Wen, H

    2012-10-01

    We describe the design and fabrication trials of x-ray absorption gratings of 200 nm period and up to 100:1 depth-to-period ratios for full-field hard x-ray imaging applications. Hard x-ray phase-contrast imaging relies on gratings of ultra-small periods and sufficient depth to achieve high sensitivity. Current grating designs utilize lithographic processes to produce periodic vertical structures, where grating periods below 2.0 μm are difficult due to the extreme aspect ratios of the structures. In our design, multiple bilayers of x-ray transparent and opaque materials are deposited on a staircase substrate, and mostly on the floor surfaces of the steps only. When illuminated by an x-ray beam horizontally, the multilayer stack on each step functions as a micro-grating whose grating period is the thickness of a bilayer. The array of micro-gratings over the length of the staircase works as a single grating over a large area when continuity conditions are met. Since the layers can be nanometers thick and many microns wide, this design allows sub-micron grating periods and sufficient grating depth to modulate hard x-rays. We present the details of the fabrication process and diffraction profiles and contact radiography images showing successful intensity modulation of a 25 keV x-ray beam. PMID:23066175

  12. Fabrication of 200 nanometer period centimeter area hard x-ray absorption gratings by multilayer deposition

    PubMed Central

    Lynch, S K; Liu, C; Morgan, N Y; Xiao, X; Gomella, A A; Mazilu, D; Bennett, E E; Assoufid, L; de Carlo, F; Wen, H

    2012-01-01

    We describe the design and fabrication trials of x-ray absorption gratings of 200 nm period and up to 100:1 depth-to-period ratios for full-field hard x-ray imaging applications. Hard x-ray phase-contrast imaging relies on gratings of ultra-small periods and sufficient depth to achieve high sensitivity. Current grating designs utilize lithographic processes to produce periodic vertical structures, where grating periods below 2.0 μm are difficult due to the extreme aspect ratios of the structures. In our design, multiple bilayers of x-ray transparent and opaque materials are deposited on a staircase substrate, and mostly on the floor surfaces of the steps only. When illuminated by an x-ray beam horizontally, the multilayer stack on each step functions as a micro-grating whose grating period is the thickness of a bilayer. The array of micro-gratings over the length of the staircase works as a single grating over a large area when continuity conditions are met. Since the layers can be nanometers thick and many microns wide, this design allows sub-micron grating periods and sufficient grating depth to modulate hard x-rays. We present the details of the fabrication process and diffraction profiles and contact radiography images showing successful intensity modulation of a 25 keV x-ray beam. PMID:23066175

  13. Making Skew-Resistant Fabrics For Composite Layups

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    1994-01-01

    Fabrics used in curved composite-material structures prevented from skewing during composite layup by weaving them in modified process in which warp and fill yarns bonded together at their points of contact. (Bonding concept may prove similarly beneficial for braided and knitted fabrics.) In modified weaving process, adhesives prevent excessive shifting of warp and fill yarns with respect to each other.

  14. Joining and fabrication of metal-matrix composite materials

    NASA Technical Reports Server (NTRS)

    Royster, D. M.; Wiant, H. R.; Bales, T. T.

    1975-01-01

    Manufacturing technology associated with developing fabrication processes to incorporate metal-matrix composites into flight hardware is studied. The joining of composite to itself and to titanium by innovative brazing, diffusion bonding, and adhesive bonding is examined. The effects of the fabrication processes on the material properties and their influence on the design of YF-12 wing panels are discussed.

  15. Determining micro- and macro- geometry of fabric and fabric reinforced composites

    NASA Astrophysics Data System (ADS)

    Huang, Lejian

    Textile composites are made from textile fabric and resin. Depending on the weaving pattern, composite reinforcements can be characterized into two groups: uniform fabric and near-net shape fabric. Uniform fabric can be treated as an assembly of its smallest repeating pattern also called a unit cell; the latter is a single component with complex structure. Due to advantages of cost savings and inherent toughness, near-net shape fabric has gained great success in composite industries, for application such as turbine blades. Mechanical properties of textile composites are mainly determined by the geometry of the composite reinforcements. The study of a composite needs a computational tool to link fabric micro- and macro-geometry with the textile weaving process and composite manufacturing process. A textile fabric consists of a number of yarns or tows, and each yarn is a bundle of fibers. In this research, a fiber-level approach known as the digital element approach (DEA) is adopted to model the micro- and macro-geometry of fabric and fabric reinforced composites. This approach determines fabric geometry based on textile weaving mechanics. A solver with a dynamic explicit algorithm is employed in the DEA. In modeling a uniform fabric, the topology of the fabric unit cell is first established based on the weaving pattern, followed by yarn discretization. An explicit algorithm with a periodic boundary condition is then employed during the simulation. After its detailed geometry is obtained, the unit cell is then assembled to yield a fabric micro-geometry. Fabric micro-geometry can be expressed at both fiber- and yarn-levels. In modeling a near-net shape fabric component, all theories used in simulating the uniform fabric are kept except the periodic boundary condition. Since simulating the entire component at the fiber-level requires a large amount of time and memory, parallel program is used during the simulation. In modeling a net-shape composite, a dynamic molding

  16. Fabrication and characterization of ZnO/AI/ZnO multilayers by simultaneous DC and RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Nagaraja, K. K.; Santhosh Kumar, A.; Nagaraja, H. S.

    2015-02-01

    The present investigation reports the fabrication and characterization of multilayered transparent electrodes by simultaneous DC and RF magnetron sputtering on glass substrates. The multilayer structure consists of three layers (ZnO/Al/ZnO). The influence of Al layer thickness on the electrical and optical properties was investigated. Optimum thickness of Al was determined for high transmittance and good electrical conductivity. High quality films having resistance as low as 25 Ω/sq with optical transmittance upto 65% were obtained at room temperature.

  17. Design and fabrication of far ultraviolet filters based on π-multilayer technology in high-k materials

    PubMed Central

    Wang, Xiao-Dong; Chen, Bo; Wang, Hai-Feng; He, Fei; Zheng, Xin; He, Ling-Ping; Chen, Bin; Liu, Shi-Jie; Cui, Zhong-Xu; Yang, Xiao-Hu; Li, Yun-Peng

    2015-01-01

    Application of π-multilayer technology is extended to high extinction coefficient materials, which is introduced into metal-dielectric filter design. Metal materials often have high extinction coefficients in far ultraviolet (FUV) region, so optical thickness of metal materials should be smaller than that of the dielectric material. A broadband FUV filter of 9-layer non-periodic Al/MgF2 multilayer was successfully designed and fabricated and it shows high reflectance in 140–180 nm, suppressed reflectance in 120–137 nm and 181–220 nm. PMID:25687255

  18. Bone formation: The rules for fabricating a composite ceramic

    SciTech Connect

    Caplan, A.I. )

    1990-01-01

    Bone, teeth and shells are complex composite ceramics which are fabricated at low temperature by living organisms. The detailed understanding of this fabrication process is required if we are to attempt to mimic this low temperature assembly process. The guiding principles and major components are outlined with the intent of establishing non-vital fabrication schemes to form a complex composite ceramic consisting of an organix matrix inorganic crystalline phase. 19 refs.

  19. Fabrication and testing of fire resistant graphite composite panels

    NASA Technical Reports Server (NTRS)

    Roper, W. D.

    1986-01-01

    Eight different graphite composite panels were fabricated using four different resin matrices. The resin matrices included Hercules 71775, a blend of vinylpolystyrpyridine and bismaleimide, H795, a bismaleimide, Cycom 6162, a phenolic, and PSP 6022m, a polystyrylpyridine. Graphite panels were fabricated using fabric or unidirectional tape. Described are the processes for preparing these panels and some of their mechanical, thermal and flammability properties. Panel properties are compared with state-of-the-art epoxy fiberglass composite panels.

  20. Zone compensated multilayer laue lens and apparatus and method of fabricating the same

    DOEpatents

    Conley, Raymond P.; Liu, Chian Qian; Macrander, Albert T.; Yan, Hanfei; Maser, Jorg; Kang, Hyon Chol; Stephenson, Gregory Brian

    2015-07-14

    A multilayer Laue Lens includes a compensation layer formed in between a first multilayer section and a second multilayer section. Each of the first and second multilayer sections includes a plurality of alternating layers made of a pair of different materials. Also, the thickness of layers of the first multilayer section is monotonically increased so that a layer adjacent the substrate has a minimum thickness, and the thickness of layers of the second multilayer section is monotonically decreased so that a layer adjacent the compensation layer has a maximum thickness. In particular, the compensation layer of the multilayer Laue lens has an in-plane thickness gradient laterally offset by 90.degree. as compared to other layers in the first and second multilayer sections, thereby eliminating the strict requirement of the placement error.

  1. Investigating Deformation and Failure Mechanisms in Nanoscale Multilayer Metallic Composites

    SciTech Connect

    Zbib, Hussein M; Bahr, David F

    2014-10-22

    Over the history of materials science there are many examples of materials discoveries that have made superlative materials; the strongest, lightest, or toughest material is almost always a goal when we invent new materials. However, often these have been a result of enormous trial and error approaches. A new methodology, one in which researchers design, from the atoms up, new ultra-strong materials for use in energy applications, is taking hold within the science and engineering community. This project focused on one particular new classification of materials; nanolaminate metallic composites. These materials, where two metallic materials are intimately bonded and layered over and over to form sheets or coatings, have been shown over the past decade to reach strengths over 10 times that of their constituents. However, they are not yet widely used in part because while extremely strong (they don’t permanently bend), they are also not particularly tough (they break relatively easily when notched). Our program took a coupled approach to investigating new materials systems within the laminate field. We used computational materials science to explore ways to institute new deformation mechanisms that occurred when a tri-layer, rather than the more common bi-layer system was created. Our predictions suggested that copper-nickel or copper-niobium composites (two very common bi-layer systems) with layer thicknesses on the order of 20 nm and then layered 100’s of times, would be less tough than a copper-nickel-niobium metallic composite of similar thicknesses. In particular, a particular mode of permanent deformation, cross-slip, could be activated only in the tri-layer system; the crystal structure of the other bi-layers would prohibit this particular mode of deformation. We then experimentally validated this predication using a wide range of tools. We utilized a DOE user facility, the Center for Integrated Nanotechnology (CINT), to fabricate, for the first time, these

  2. Automated Fabrication Technologies for High Performance Polymer Composites

    NASA Technical Reports Server (NTRS)

    Shuart , M. J.; Johnston, N. J.; Dexter, H. B.; Marchello, J. M.; Grenoble, R. W.

    1998-01-01

    New fabrication technologies are being exploited for building high graphite-fiber-reinforced composite structure. Stitched fiber preforms and resin film infusion have been successfully demonstrated for large, composite wing structures. Other automatic processes being developed include automated placement of tacky, drapable epoxy towpreg, automated heated head placement of consolidated ribbon/tape, and vacuum-assisted resin transfer molding. These methods have the potential to yield low cost high performance structures by fabricating composite structures to net shape out-of-autoclave.

  3. Fabrication of multi-layer polymeric micro-sieve having narrow slot pores with conventional ultraviolet-lithography and micro-fabrication techniques

    PubMed Central

    Ebrahimi Warkiani, Majid; Lou, Chao-Ping; Gong, Hai-Qing

    2011-01-01

    Fast detection of waterborne pathogens is important for securing the hygiene of drinking water. Detection of pathogens in water at low concentrations and minute quantities demands rapid and efficient enrichment methods in order to improve the signal-to-noise ratio of bio-sensors. We propose and demonstrate a low cost and rapid method to fabricate a multi-layer polymeric micro-sieve using conventional lithography techniques. The micro-fabricated micro-sieves are made of several layers of SU-8 photoresist using multiple coating and exposure steps and a single developing process. The obtained micro-sieves have good mechanical properties, smooth surfaces, high porosity (≈40%), and narrow pore size distribution (coefficient of variation < 3.33%). Sample loading and back-flushing using the multi-layer micro-sieve resulted in more than 90% recovery of pathogens, which showed improved performance than current commercial filters. PMID:22662051

  4. Composition and method for making polyimide resin-reinforced fabric

    NASA Technical Reports Server (NTRS)

    Serafini, T. T.; Delvigs, P. (Inventor)

    1981-01-01

    A composition for making polyimide resin reinforced fibers or fabric is discussed. The composition includes a polyfunctional ester, a polyfunctional amine, and an end capping agent. The composition is impregnated into fibers or fabric and heated to form prepreg material. The tack retention characteristics of this prepreg material are improved by incorporating into the composition a liquid olefinic material compatible with the other ingredients of the composition. The prepreg material is heated at a higher temperature to effect formation of the polyimide resin and the monomeric additive is incorporated in the polyimide polymer structure.

  5. Composite metal foil and ceramic fabric materials

    DOEpatents

    Webb, B.J.; Antoniak, Z.I.; Prater, J.T.; DeSteese, J.G.

    1992-03-24

    The invention comprises new materials useful in a wide variety of terrestrial and space applications. In one aspect, the invention comprises a flexible cloth-like material comprising a layer of flexible woven ceramic fabric bonded with a layer of metallic foil. In another aspect, the invention includes a flexible fluid impermeable barrier comprising a flexible woven ceramic fabric layer having metal wire woven therein. A metallic foil layer is incontinuously welded to the woven metal wire. In yet another aspect, the invention includes a material comprising a layer of flexible woven ceramic fabric bonded with a layer of an organic polymer. In still another aspect, the invention includes a rigid fabric structure comprising a flexible woven ceramic fabric and a resinous support material which has been hardened as the direct result of exposure to ultraviolet light. Inventive methods for producing such material are also disclosed. 11 figs.

  6. Composite metal foil and ceramic fabric materials

    DOEpatents

    Webb, Brent J.; Antoniak, Zen I.; Prater, John T.; DeSteese, John G.

    1992-01-01

    The invention comprises new materials useful in a wide variety of terrestrial and space applications. In one aspect, the invention comprises a flexible cloth-like material comprising a layer of flexible woven ceramic fabric bonded with a layer of metallic foil. In another aspect, the invention includes a flexible fluid impermeable barrier comprising a flexible woven ceramic fabric layer having metal wire woven therein. A metallic foil layer is incontinuously welded to the woven metal wire. In yet another aspect, the invention includes a material comprising a layer of flexible woven ceramic fabric bonded with a layer of an organic polymer. In still another aspect, the invention includes a rigid fabric structure comprising a flexible woven ceramic fabric and a resinous support material which has been hardened as the direct result of exposure to ultraviolet light. Inventive methods for producing such material are also disclosed.

  7. Interphase layer optimization for metal matrix composites with fabrication considerations

    NASA Technical Reports Server (NTRS)

    Morel, M.; Saravanos, D. A.; Chamis, C. C.

    1991-01-01

    A methodology is presented to reduce the final matrix microstresses for metal matrix composites by concurrently optimizing the interphase characteristics and fabrication process. Application cases include interphase tailoring with and without fabrication considerations for two material systems, graphite/copper and silicon carbide/titanium. Results indicate that concurrent interphase/fabrication optimization produces significant reductions in the matrix residual stresses and strong coupling between interphase and fabrication tailoring. The interphase coefficient of thermal expansion and the fabrication consolidation pressure are the most important design parameters and must be concurrently optimized to further reduce the microstresses to more desirable magnitudes.

  8. Fabrication of toroidal composite pressure vessels. Final report

    SciTech Connect

    Dodge, W.G.; Escalona, A.

    1996-11-24

    A method for fabricating composite pressure vessels having toroidal geometry was evaluated. Eight units were fabricated using fibrous graphite material wrapped over a thin-walled aluminum liner. The material was wrapped using a machine designed for wrapping, the graphite material was impregnated with an epoxy resin that was subsequently thermally cured. The units were fabricated using various winding patterns. They were hydrostatically tested to determine their performance. The method of fabrication was demonstrated. However, the improvement in performance to weight ratio over that obtainable by an all metal vessel probably does not justify the extra cost of fabrication.

  9. Fabrication and in vitro evaluation of stable collagen/hyaluronic acid biomimetic multilayer on titanium coatings

    PubMed Central

    Ao, Haiyong; Xie, Youtao; Tan, Honglue; Yang, Shengbing; Li, Kai; Wu, Xiaodong; Zheng, Xuebin; Tang, Tingting

    2013-01-01

    Layer-by-layer (LBL) self-assembly technique has been proved to be a highly effective method to immobilize the main components of the extracellular matrix such as collagen and hyaluronic acid on titanium-based implants and form a polyelectrolyte multilayer (PEM) film by electrostatic interaction. However, the formed PEM film is unstable in the physiological environment and affects the long-time effectiveness of PEM film. In this study, a modified LBL technology has been developed to fabricate a stable collagen/hyaluronic acid (Col/HA) PEM film on titanium coating (TC) by introducing covalent immobilization. Scanning electron microscopy, diffuse reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the PEM film. Results of Sirius red staining demonstrated that the chemical stability of PEM film was greatly improved by covalent cross-linking. Cell culture assays further illustrated that the functions of human mesenchymal stem cells, such as attachment, spreading, proliferation and differentiation, were obviously enhanced by the covalently immobilized Col/HA PEM on TCs compared with the absorbed Col/HA PEM. The improved stability and biological properties of the Col/HA PEM covalently immobilized TC may be beneficial to the early osseointegration of the implants. PMID:23635490

  10. Fabrication of Optical Multilayer Devices from Porous Silicon Coatings with Closed Porosity by Magnetron Sputtering.

    PubMed

    Caballero-Hernández, Jaime; Godinho, Vanda; Lacroix, Bertrand; Jiménez de Haro, Maria C; Jamon, Damien; Fernández, Asunción

    2015-07-01

    The fabrication of single-material photonic-multilayer devices is explored using a new methodology to produce porous silicon layers by magnetron sputtering. Our bottom-up methodology produces highly stable amorphous porous silicon films with a controlled refractive index using magnetron sputtering and incorporating a large amount of deposition gas inside the closed pores. The influence of the substrate bias on the formation of the closed porosity was explored here for the first time when He was used as the deposition gas. We successfully simulated, designed, and characterized Bragg reflectors and an optical microcavity that integrates these porous layers. The sharp interfaces between the dense and porous layers combined with the adequate control of the refractive index and thickness allowed for excellent agreement between the simulation and the experiments. The versatility of the magnetron sputtering technique allowed for the preparation of these structures for a wide range of substrates such as polymers while also taking advantage of the oblique angle deposition to prepare Bragg reflectors with a controlled lateral gradient in the stop band wavelengths. PMID:26046812

  11. Process for fabricating high reflectance-low stress Mo--Si multilayer reflective coatings

    DOEpatents

    Montcalm, Claude; Mirkarimi, Paul B.

    2001-01-01

    A high reflectance-low stress Mo--Si multilayer reflective coating particularly useful for the extreme ultraviolet (EUV) wavelength region. While the multilayer reflective coating has particular application for EUV lithography, it has numerous other applications where high reflectance and low stress multilayer coatings are utilized. Multilayer coatings having high near-normal incidence reflectance (R.gtoreq.65%) and low residual stress (.ltoreq.100 MPa) have been produced using thermal and non-thermal approaches. The thermal approach involves heating the multilayer coating to a given temperature for a given time after deposition in order to induce structural changes in the multilayer coating that will have an overall "relaxation" effect without reducing the reflectance significantly.

  12. Synthetic, Multi-Layer, Self-Oscillating Vocal Fold Model Fabrication

    PubMed Central

    Murray, Preston R.; Thomson, Scott L.

    2011-01-01

    , however, have either been homogenous (one-layer models) or have been fabricated using two materials of differing stiffness (two-layer models). This approach does not allow for representation of the actual multi-layer structure of the human vocal folds 1 that plays a central role in governing vocal fold flow-induced vibratory response. Consequently, one- and two-layer synthetic vocal fold models have exhibited disadvantages 3,6,8 such as higher onset pressures than what are typical for human phonation (onset pressure is the minimum lung pressure required to initiate vibration), unnaturally large inferior-superior motion, and lack of a "mucosal wave" (a vertically-traveling wave that is characteristic of healthy human vocal fold vibration). In this paper, fabrication of a model with multiple layers of differing material properties is described. The model layers simulate the multi-layer structure of the human vocal folds, including epithelium, superficial lamina propria (SLP), intermediate and deep lamina propria (i.e., ligament; a fiber is included for anterior-posterior stiffness), and muscle (i.e., body) layers 1. Results are included that show that the model exhibits improved vibratory characteristics over prior one- and two-layer synthetic models, including onset pressure closer to human onset pressure, reduced inferior-superior motion, and evidence of a mucosal wave. PMID:22157812

  13. Synthetic, multi-layer, self-oscillating vocal fold model fabrication.

    PubMed

    Murray, Preston R; Thomson, Scott L

    2011-01-01

    been homogenous (one-layer models) or have been fabricated using two materials of differing stiffness (two-layer models). This approach does not allow for representation of the actual multi-layer structure of the human vocal folds that plays a central role in governing vocal fold flow-induced vibratory response. Consequently, one- and two-layer synthetic vocal fold models have exhibited disadvantages such as higher onset pressures than what are typical for human phonation (onset pressure is the minimum lung pressure required to initiate vibration), unnaturally large inferior-superior motion, and lack of a "mucosal wave" (a vertically-traveling wave that is characteristic of healthy human vocal fold vibration). In this paper, fabrication of a model with multiple layers of differing material properties is described. The model layers simulate the multi-layer structure of the human vocal folds, including epithelium, superficial lamina propria (SLP), intermediate and deep lamina propria (i.e., ligament; a fiber is included for anterior-posterior stiffness), and muscle (i.e., body) layers. Results are included that show that the model exhibits improved vibratory characteristics over prior one- and two-layer synthetic models, including onset pressure closer to human onset pressure, reduced inferior-superior motion, and evidence of a mucosal wave. PMID:22157812

  14. Adhesive Wear and Frictional Behavior of Multilayered Polyester Composite Based on Betelnut Fiber Mats Under Wet Contact Conditions

    NASA Astrophysics Data System (ADS)

    Yousif, B. F.; Devadas, Alvin; Yusaf, Talal F.

    In the current study, a multilayered polyester composite based on betelnut fiber mats is fabricated. The adhesive wear and frictional performance of the composite was studied against a smooth stainless steel at different sliding distances (0-6.72 km) and applied loads (20-200 N) at 2.8 m/s sliding velocity. Variations in specific wear rate and friction coefficient were evaluated at two different orientations of fiber mat; namely parallel (P-O) and normal (N-O). Results obtained were presented against sliding distance. The worn surfaces of the composite were studied using an optical microscope. The effect of the composite sliding on the stainless steel counterface roughness was investigated. The results revealed that the wear performance of betelnut fiber reinforced polyester (BFRP) composite under wet contact condition was highly dependent on test parameters and fiber mat orientation. The specific wear rate performance for each orientation showed an inverse relationship to sliding distance. BFRP composite in N-O exhibited better wear performance compared with P-O. However, the friction coefficient in N-O was higher than that in P-O at lower range of applied load. The predominant wear mechanism was debonding of fiber with no pullout or ploughing. Moreover, at higher applied loads, micro- and macrocracking and fracture were observed in the resinous region.

  15. The Design, Fabrication, and Testing of Composite Heat Exchange Coupons

    NASA Technical Reports Server (NTRS)

    Quade, Derek J.; Meador, Michael A.; Shin, Euy-Sik; Johnston, James C.; Kuczmarski, Maria A.

    2011-01-01

    Several heat exchanger (HX) test panels were designed, fabricated and tested at the NASA Glenn Research Center to explore the fabrication and performance of several designs for composite heat exchangers. The development of these light weight, high efficiency air-liquid test panels was attempted using polymer composites and carbon foam materials. The fundamental goal of this effort was to demonstrate the feasibility of the composite HX for various space exploration and thermal management applications including Orion CEV and Altair. The specific objectives of this work were to select optimum materials, designs, and to optimize fabrication procedures. After fabrication, the individual design concept prototypes were tested to determine their thermal performance and to guide the future development of full-size engineering development units (EDU). The overall test results suggested that the panel bonded with pre-cured composite laminates to KFOAM Grade L1 scored above the other designs in terms of ease of manufacture and performance.

  16. Degradable Polymer Composites Fabricated from Starch and Alkyl Cyanoacrylate Monomer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Degradable polymer composites are fabricated from alkyl cyanoacrylate monomer and starch without special equipment. Alkyl cyanoacrylate, which is a major component of “super glue”, is a monomer that polymerizes at room temperature in the presence of initiators. During the fabrication of polymer com...

  17. Piezoelectric Sol-Gel Composite Film Fabrication by Stencil Printing.

    PubMed

    Kaneko, Tsukasa; Iwata, Kazuki; Kobayashi, Makiko

    2015-09-01

    Piezoelectric films using sol-gel composites could be useful as ultrasonic transducers in various industrial fields. For sol-gel composite film fabrication, the spray coating technique has been used often because of its adaptability for various substrates. However, the spray technique requires multiple spray coating processes and heating processes and this is an issue of concern, especially for on-site fabrication in controlled areas. Stencil printing has been developed to solve this issue because this method can be used to fabricate thick sol-gel composite films with one coating process. In this study, PbTiO3 (PT)/Pb(Zr,Ti)O3 (PZT) films, PZT/PZT films, and Bi4Ti3O12 (BiT)/PZT films were fabricated by stencil printing, and PT/ PZT films were also fabricated using the spray technique. After fabrication, a thermal cycle test was performed for the samples to compare their ultrasonic performance. The sensitivity and signal-to-noise-ratio (SNR) of the ultrasonic response of PT/PZT fabricated by stencil printing were equivalent to those of PT/PZT fabricated by the spray technique, and better than those of other samples between room temperature and 300°C. Therefore, PT/PZT films fabricated by stencil printing could be a good candidate for nondestructive testing (NDT) ultrasonic transducers from room temperature to 300°C. PMID:26688872

  18. Multilayer ceramic oxide solid electrolyte for fuel cells and electrolysis cells and method for fabrication thereof

    NASA Technical Reports Server (NTRS)

    Schroeder, James E. (Inventor); Anderson, Harlan U. (Inventor)

    1990-01-01

    An unitary layered ceramic structure is disclosed which comprises co-sintered layers. The co-sintered structure comprises a sintered central layer of yttria stabilized zirconia (YSZ) which is about 8 mole percent yttria and having a density of at least about 95% of theoretical, and sintered outer layers of strontium lanthanum manganite (LSM) having the approximate molecular composition La.sub.0.8 Sr.sub.0.2 MnO.sub.3, having a density from about 50 to about 60% of theoretical, and having interconnected porosity from about 40 to 50% with an interconnected pore diameter from about one micron to about five microns. The sintered central layer is sandwiched by and bonded and sintered to the outer layers and is essentially free of significant amounts of manganese. A process for making the unitary composition-of-matter is also disclosed which involves tape casting a LSM tape and then on top thereof casting a YSZ tape. The process comprises presintering LSM powder at 1250.degree. F., crushing the presintered commercially available LSM powder, forming a slurry with the crushed LSM, a binder and solvent, tape casting the slurry and allowing the slurry to air dry. A mixture of commercially available submicron size particle YSZ powder is milled with a dispersant and solvent to disperse the YSZ particles thereby forming a dispersed YSZ slurry. The YSZ slurry is then tape cast on the dried LSM tape. If desired, a third layer of LSM can be cast on top of the dried YSZ layer. After drying the composite LSM/YSZ and LSM/YSZ/LSM tapes are fired at 1300.degree. C. No migration of manganese into the YSZ layer was observed with scanning electron microscope/edax in the sintered multilayer tape.

  19. Fabrication and optical properties of conjugated polymer composited multi-arrays of TiO2 nanowires via sequential electrospinning.

    PubMed

    Shim, Hee-Sang; Kim, Jeong Won; Kim, Won Bae

    2009-08-01

    We report here a simple method of fabricating multi-layered architectures of cross-aligned inorganic nanowires via sequential electrospinning method equipped with a newly devised collector that is able to prepare aligned inorganic nanowires. The multi-layers of aligned TiO2 nanowires can be deposited in a proportional increment of weight with collecting time and reveal a large reduction of electrical resistance by at least 30% compared to a randomly collected TiO2 nanowire structure. The solar cell performance of the cross-aligned TiO2 nanowire layers composited with a conjugated polymer of poly[2-methoxy, 5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEH-PPV) is significantly enhanced by 70% or greater in the organic-inorganic hybrid photovoltaic devices than that fabricated with the randomly-collected TiO2 nanowire photoanode. PMID:19928140

  20. Investigation on mechanical properties of basalt composite fabrics (experiment study)

    NASA Astrophysics Data System (ADS)

    Talebi Mazraehshahi, H.; Zamani, H.

    2010-06-01

    To fully appreciate the role and application of composite materials to structures, correct understanding of mechanical behaviors required for selection of optimum material. Fabric reinforced composites are composed of a matrix that is reinforced with pliable fabric, glass fabric is most popular reinforcement for different application specially in aircraft structure, although other fabric material are also used. At this study new fabric material called basalt with epoxy resin introduced and mechanical behaviors of this material investigated from view point of testing. For this study two type of fabric with different thickness used. Comparison between this composite reinforcement with popular reinforcement as carbon, glass, kevlar performed. To determine mechanical properties of epoxy based basalt fabric following test procedure performed : 1). Tensile testing according to ASTM D3039 in 0° and 90° direction to find ultimate strength in tension and shear, modulus of elasticity, elangation and ultimate strain. 2). Compression testing according to EN 2850 ultimate compression strength and maximum deformation under compression loading. 3). Shear testing according to ASTM D3518-94 to find in plane shear response of polymer matrix composites materials. 4). Predict flexural properties of sandwich construction which manufactured from basalt facing with PVC foam core according to ASTM C393-94. Material strength properties must be based on enough tests of material to meet the test procedure specifications [1]. For this reason six specimens were manufactured for testing and the tests were performed on them using an INSTRON machine model 5582. In the study, the effect of percent of resin in basalt reinforced composite was investigated. Also the weights of the ballast based composites with different percent of resin were measured with conventional composites. As the weight is an important parameter in aerospace industry when the designer wants to replace one material with

  1. Controllable synthesis of molybdenum tungsten disulfide alloy for vertically composition-controlled multilayer

    PubMed Central

    Song, Jeong-Gyu; Ryu, Gyeong Hee; Lee, Su Jeong; Sim, Sangwan; Lee, Chang Wan; Choi, Taejin; Jung, Hanearl; Kim, Youngjun; Lee, Zonghoon; Myoung, Jae-Min; Dussarrat, Christian; Lansalot-Matras, Clement; Park, Jusang; Choi, Hyunyong; Kim, Hyungjun

    2015-01-01

    The effective synthesis of two-dimensional transition metal dichalcogenides alloy is essential for successful application in electronic and optical devices based on a tunable band gap. Here we show a synthesis process for Mo1−xWxS2 alloy using sulfurization of super-cycle atomic layer deposition Mo1−xWxOy. Various spectroscopic and microscopic results indicate that the synthesized Mo1−xWxS2 alloys have complete mixing of Mo and W atoms and tunable band gap by systematically controlled composition and layer number. Based on this, we synthesize a vertically composition-controlled (VCC) Mo1−xWxS2 multilayer using five continuous super-cycles with different cycle ratios for each super-cycle. Angle-resolved X-ray photoemission spectroscopy, Raman and ultraviolet–visible spectrophotometer results reveal that a VCC Mo1−xWxS2 multilayer has different vertical composition and broadband light absorption with strong interlayer coupling within a VCC Mo1−xWxS2 multilayer. Further, we demonstrate that a VCC Mo1−xWxS2 multilayer photodetector generates three to four times greater photocurrent than MoS2- and WS2-based devices, owing to the broadband light absorption. PMID:26204328

  2. Multilayer Graphene Enables Higher Efficiency in Improving Thermal Conductivities of Graphene/Epoxy Composites.

    PubMed

    Shen, Xi; Wang, Zhenyu; Wu, Ying; Liu, Xu; He, Yan-Bing; Kim, Jang-Kyo

    2016-06-01

    The effects of number of graphene layers (n) and size of multilayer graphene sheets on thermal conductivities (TCs) of their epoxy composites are investigated. Molecular dynamics simulations show that the in-plane TCs of graphene sheets and the TCs across the graphene/epoxy interface simultaneously increase with increasing n. However, such higher TCs of multilayer graphene sheets will not translate into higher TCs of bulk composites unless they have large lateral sizes to maintain their aspect ratios comparable to the monolayer counterparts. The benefits of using large, multilayer graphene sheets are confirmed by experiments, showing that the composites made from graphite nanoplatelets (n > 10) with over 30 μm in diameter deliver a TC of ∼1.5 W m(-1) K(-1) at only 2.8 vol %, consistently higher than those containing monolayer or few-layer graphene at the same graphene loading. Our findings offer a guideline to use cost-effective multilayer graphene as conductive fillers for various thermal management applications. PMID:27140423

  3. Multilayer transfer printing of electroactive thin film composites.

    PubMed

    Cebeci, Fevzi Ç; Schmidt, Daniel J; Hammond, Paula T

    2014-11-26

    We demonstrate the high fidelity transfer printing of an electroactive polymer nanocomposite thin film onto a conductive electrode. Polyelectrolyte multilayer thin films of thickness ∼200 nm containing 68 vol % Prussian Blue nanoparticles are assembled on a UV-curable photopolymer stamp and transferred in their entirety onto ITO-coated glass creating ∼2.5 μm-wide line patterns with ∼1.25 μm spacing. AFM and SEM are used to investigate pattern fidelity and morphology, while cyclic voltammetry confirms the electroactive nature of the film and electrical connectivity with the electrode. The patterning strategy presented here could be used to pattern electroactive thin films containing a high density of nanoparticles onto individually addressable microelectrodes for a variety of applications ranging from biosensor arrays to flexible electronics. PMID:25372508

  4. Structure of multilayered Cr(Al)N/SiO{sub x} nanocomposite coatings fabricated by differential pumping co-sputtering

    SciTech Connect

    Kawasaki, Masahiro; Nose, Masateru; Onishi, Ichiro; Shiojiri, Makoto

    2013-11-11

    A Cr(Al)N/38 vol. % SiO{sub x} hard coating was prepared on a (001) Si substrate at 250 °C in a differential pumping co-sputtering system, which has two chambers for radio frequency (RF) sputtering and a substrate holder rotating on the chambers. The composite coating was grown by alternate sputter-depositions from CrAl and SiO{sub 2} targets with flows of N{sub 2}+Ar and Ar at RF powers of 200 and 75 W, respectively, on transition layers grown on the substrate. Analytical electron microscopy reveled that the Cr(Al)N/SiO{sub x} coating had a multilayered structure of Cr(Al)N crystal layers ∼1.6 nm thick and two-dimensionally dispersed amorphous silicon oxide (a-SiO{sub x}) particles with sizes of ∼1 nm or less. The a-SiO{sub x} particles were enclosed with the Cr(Al)N layers. The coating had a low indentation hardness of ∼25 GPa at room temperature, due to a high oxide fraction of 38 vol. % and a low substrate rotational speed of 1 rpm. Faster rotation and lower oxide fraction would make a-SiO{sub x} particles smaller, resulting in the formation of Cr(Al)N crystal including the very fine a-SiO{sub x} particles with small number density. They would work as obstacles for the lattice deformation of the Cr(Al)N crystals. We have fabricated a superhard coating of Cr(Al)N/17 vol. % SiO{sub x} with a hardness of 46 GPa prepared at 12 rpm.

  5. Structure of multilayered Cr(Al)N/SiOx nanocomposite coatings fabricated by differential pumping co-sputtering

    NASA Astrophysics Data System (ADS)

    Kawasaki, Masahiro; Nose, Masateru; Onishi, Ichiro; Shiojiri, Makoto

    2013-11-01

    A Cr(Al)N/38 vol. % SiOx hard coating was prepared on a (001) Si substrate at 250 °C in a differential pumping co-sputtering system, which has two chambers for radio frequency (RF) sputtering and a substrate holder rotating on the chambers. The composite coating was grown by alternate sputter-depositions from CrAl and SiO2 targets with flows of N2+Ar and Ar at RF powers of 200 and 75 W, respectively, on transition layers grown on the substrate. Analytical electron microscopy reveled that the Cr(Al)N/SiOx coating had a multilayered structure of Cr(Al)N crystal layers ˜1.6 nm thick and two-dimensionally dispersed amorphous silicon oxide (a-SiOx) particles with sizes of ˜1 nm or less. The a-SiOx particles were enclosed with the Cr(Al)N layers. The coating had a low indentation hardness of ˜25 GPa at room temperature, due to a high oxide fraction of 38 vol. % and a low substrate rotational speed of 1 rpm. Faster rotation and lower oxide fraction would make a-SiOx particles smaller, resulting in the formation of Cr(Al)N crystal including the very fine a-SiOx particles with small number density. They would work as obstacles for the lattice deformation of the Cr(Al)N crystals. We have fabricated a superhard coating of Cr(Al)N/17 vol. % SiOx with a hardness of 46 GPa prepared at 12 rpm.

  6. Fabrication Routes for Continuous Fiber-Reinforced Ceramic Composites (CFCC)

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A.; Bansal, Narottam P.

    1998-01-01

    The primary approaches used for fabrication of continuous fiber-reinforced ceramic composite (CFCC) components have been reviewed. The CFCC fabrication issues related to fiber, interface, and matrix have been analyzed. The capabilities. advantages and limitations of the five matrix-infiltration routes have been compared and discussed. Today. the best fabrication route for the CFCC end-user is not clear and compromises need to be made depending on the details of the CFCC application. However, with time, this problem should be reduced as research continues to develop advanced CFCC constituents and fabrication routes.

  7. Fabrication Routes for Continuous Fiber-Reinforced Ceramic Composites (CFCC)

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A.; Bansal, Narottam P.

    1998-01-01

    The primary approaches used for fabrication of continuous fiber-reinforced ceramic composite (CFCC) components have been reviewed. The CFCC fabrication issues related to fiber, interface, and matrix have been analyzed. The capabilities, advantages and limitations of the five matrix-infiltration routes have been compared and discussed. Today, the best fabrication route for the CFCC end-user is not clear and compromises need to be made depending on the details of the CFCC application. However, with time, this problem should be reduced as research continues to develop advanced CFCC constituents and fabrication routes.

  8. Multilayered composite proton exchange membrane and a process for manufacturing the same

    DOEpatents

    Santurri, Pasco R; Duvall, James H; Katona, Denise M; Mausar, Joseph T; Decker, Berryinne

    2015-05-05

    A multilayered membrane for use with fuel cells and related applications. The multilayered membrane includes a carrier film, at least one layer of an undoped conductive polymer electrolyte material applied onto the carrier film, and at least one layer of a conductive polymer electrolyte material applied onto the adjacent layer of polymer electrolyte material. Each layer of conductive polymer electrolyte material is doped with a plurality of nanoparticles. Each layer of undoped electrolyte material and doped electrolyte material may be applied in an alternating configuration, or alternatively, adjacent layers of doped conductive polymer electrolyte material is employed. The process for producing a multilayered composite membrane includes providing a carrier substrate and solution casting a layer of undoped conductive polymer electrolyte material and a layer of conductive polymer electrolyte material doped with nanoparticles in an alternating arrangement or in an arrangement where doped layers are adjacent to one another.

  9. Influence of the Geometric Parameters on the Mechanical Behaviour of Fabric Reinforced Composite Laminates

    NASA Astrophysics Data System (ADS)

    Axinte, Andrei; Taranu, Nicolae; Bejan, Liliana

    2016-05-01

    A polymer fabric reinforced composite is a high performance material, which combines strength of the fibres with the flexibility and ductility of the matrix. For a better drapeability, the tows of fibres are interleaved, resulting the woven fabric, used as reinforcement. The complex geometric shape of the fabric is of paramount importance in establishing the deformability of the textile reinforced composite laminates. In this paper, an approach based on Classical Lamination Theory (CLT), combined with Finite Element Methods (FEM), using Failure Analysis and Internal Load Redistribution, is utilised, in order to compare the behaviour of the material under specific loads. The main goal is to analyse the deformability of certain types of textile reinforced composite laminates, using carbon fibre satin as reinforcement and epoxy resin as matrix. This is accomplished by studying the variation of the in-plane strains, given the fluctuation of several geometric parameters, namely the width of the reinforcing tow, the gap between two consecutive tows, the angle of laminae in a multi-layered configuration and the tows fibre volume fraction.

  10. Multilayered film microreactors fabricated by a one-step thermal bonding technique with high reproducibility and their applications.

    PubMed

    Min, Kyoung-Ik; Kim, Jin-Oh; Kim, Heejin; Im, Do Jin; Kim, Dong-Pyo

    2016-03-21

    We report the versatile uses of multilayered polyimide (PI) film microreactors with various functions including pressure tolerance, three-dimensional mixing and multistep membrane emulsification. Such PI film microreactors were fabricated by a simple one-step thermal bonding technique with high reproducibility. Upon bonding at 300 °C for 1 hour, the thin and flexible film microdevices could withstand pressure up to 8.6 MPa and 16.3 MPa with PI adhesive film or fluoropolymer adhesive, respectively, due to differences in wettability. The hydrophilic and hydrophobic microchannel devices were used to generate monodisperse oil-in-water (O/W) and water-in-oil (W/O) droplets, and polymer micro/nanoparticles at a high generation frequency. A monolithic and chemical resistant film microreactor with a three-dimensional serpentine microchannel was used for the selective reduction of ester to aldehyde by efficient mixing and quenching in a flash chemistry manner, within a several 10(1) millisecond time scale. Furthermore, a novel multilayered film microreactor for organic-aqueous biphasic interfacial reactions was devised by embedding a membrane layer to induce chaotic mixing in both the interface and emulsified phase by flowing through multiple numbers of meshed structures along the hydrophobic channel. This simple and economic fabrication technique significantly facilitates mass production of multilayered film devices that could be useful as a platform for various microfluidic applications in chemistry and biology. PMID:26886679

  11. Increased Multilayer Fabrication and RF Characterization of a High-Density Stacked MIM Capacitor Based on Selective Etching

    SciTech Connect

    Tseng, VFG; Xie, HK

    2014-07-01

    This paper presents the fabrication and characterization of a high-density multilayer stacked metal-insulator-metal (MIM) capacitor based on a novel process of depositing the MIM multilayer on pillars followed by polishing and selective etching steps to form a stacked capacitor with merely three photolithography steps. In this paper, the pillars were made of glass to prevent substrate loss, whereas an oxide-nitride-oxide dielectric was employed for lower leakage, better voltage/frequency linearity, and better stress compensation. MIM capacitors with six dielectric layers were successfully fabricated, yielding capacitance density of 3.8 fF/mu m(2), maximum capacitance of 2.47 nF, and linear and quadratic voltage coefficients of capacitance below 21.2 ppm/V and 2.31 ppm/V-2. The impedance was measured from 40 Hz to 3 GHz, and characterized by an analytically derived equivalent circuit model to verify the radio frequency applicability. The multilayer stacking-induced plate resistance mismatch and its effect on the equivalent series resistance (ESR) and effective capacitance was also investigated, which can be counteracted by a corrected metal thickness design. A low ESR of 800 m Omega was achieved, whereas the self-resonance frequency was >760 MHz, successfully demonstrating the feasibility of this method to scale up capacitance densities for high-quality-factor, high-frequency, and large-value MIM capacitors.

  12. Multilayer Electroactive Polymer Composite Material Comprising Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2009-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  13. Calculation of compositional dependence of stresses in GaInAs/GaAs strained multilayer heterostructures

    NASA Astrophysics Data System (ADS)

    Nakajima, Kazuo

    1993-02-01

    A theoretical model was proposed to calculate the stress in strained multilayer heterostructures. In this model, each composed crystal layer is divided into many imaginary thin layers. The face force, moment and strained balance were considered over all the imaginary thin layers with coherent interfaces. The accurate bending moment for multilayer heterostructures was derived by expanding Davidenkov's expression of a two-phase composite layer, and it was used in the model. Using this model, the stresses at 25°C were calculated for both the GaInAs/GaAs strained multilayer heterostructure and the GaInAs/GaAs single layer heterostructure, and were compared with each other. In this calculation, the relative thickness of GaInAs layers in the GaInAs/GaAs strained multilayer heterostructure is set up to be equal to that of the GaInAs layer in the GaInAs/GaAs single layer heterostructure. The stress in both the structures was calculated over the entire GaInAs layer composition range. The relative stress in the GaInAs/GaAs bottom heterointerface of the multilayer heterostructure is smaller than that in the GaInAs/GaAs heterointerface of the single layer heterostructure especially for In-rich GaInAs. However, the absolute stress in the GaInAs layer at the bottom heterointerface of the multilayer heterostructure is larger than that in the GaInAs layer at the heterointerface of the single layer heterostructure over the entire GaInAs composition range. The difference between the stresses of both heterostructures increases as the thickness of the GaInAs layer increases. The total thickness of GaInAs layers in the multilayer heterostructure corresponding to a constant interfacial relative stress decreases as the Ga composition in the GaInAs layers decreases and it abruptly decreases when the Ga composition is smaller than 0.4. The relative stress in the GaInAs/GaAs bottom heterointerface of the multilayer heterostructure decreases as the thickness of the GaAs barrier layer

  14. Fabrication of Multi-Ply Birefringent Fibrous Composite Laminates

    NASA Technical Reports Server (NTRS)

    Daniel, I.; Niiro, T.

    1984-01-01

    Fabrication method produces unidirectional, multi-ply, transparent birefringent fibrous composite laminates for use in macromechanical stress analysis conducted by means of anisotropic photoelasticity. New laminates glass-fiber-reinforced plastics for which matrix and fibers have same index of refraction. Method utilized in structural applications of composites.

  15. Laser-Generated Lamb Waves Propagation in Multilayered Plates Composed of Viscoelastic Fiber-reinforced Composite Materials

    NASA Astrophysics Data System (ADS)

    Sun, Hong-xiang; Zhang, Shu-yi; Yuan, Shou-qi; Guan, Yi-jun; Ge, Yong

    2016-07-01

    The propagation characteristics of laser-generated Lamb waves in multilayered fiber-reinforced composite plates with different fiber orientations and number of layers have been investigated quantitatively. Considering the viscoelasticity of the composite materials, we have set up finite element models for simulating the laser-generated Lamb waves in two types of the multilayered composite plates. In the first type, different fiber orientations are adopted. In the second one, different number of layers are considered. The results illustrate the occurrence of attenuation and dispersion, which is induced by the viscoelasticity and multilayer structure, respectively.

  16. Recent developments in multi-layer flat knitting technology for waste free production of complex shaped 3D-reinforcing structures for composites

    NASA Astrophysics Data System (ADS)

    Trümper, W.; Lin, H.; Callin, T.; Bollengier, Q.; Cherif, C.; Krzywinski, S.

    2016-07-01

    Constantly increasing prices for raw materials and energy as well as the current discourse on the reduction of CO2-emissions places a special emphasis on the advantages of lightweight constructions and its resource conserving production methods. Fibre-reinforced composites are already seeing a number of applications in automobile, energy and mechanical engineering. Future applications within the named areas require greater material and energy efficiency and therefore manufacturing methods for textile preforms and lightweight constructions enabling an optimal arrangement of the reinforcing fibres while in the same time limiting waste to a minimum. One manufacturing method for textile reinforced preforms fulfilling quite many of the named requirements is the multilayer weft knitting technology. Multilayer weft knitted fabrics containing straight reinforcing yarns at least in two directions. The arrangement of these yarns is fixed by the loop yarn. Used yarn material in each knitting row is adaptable e. g. according to the load requirements or for the local integration of sensors. Draping properties of these fabrics can be varied within a great range and through this enabling draping of very complex shaped 3D-preforms without wrinkles from just one uncut fabric. The latest developments at ITM are concentrating on the development of a full production chain considering the 3D-CAD geometry, the load analysis, the generation of machine control programs as well as the development of technology and machines to enable the manufacturing of innovative net shape 3D-multilayer weft knitted fabrics such as complex shaped spacer fabrics and tubular fabrics with biaxial reinforcement.

  17. Fabrication of thick multilayered steel structure using A516 Grade 70 by multipass friction stir welding †

    DOE PAGESBeta

    Lim, Y. C.; Sanderson, S.; Mahoney, M.; Wang, Y.; Chen, J.; David, S. A.; Feng, Z.

    2016-04-06

    Here, we fabricated a thick-sectioned multilayered steel structure by multipass friction stir welding on A516 Grade 70 steel. Tensile strength of the multilayered samples was comparable to that of the base metal. Failure was located in the base metal when a defect-free sample was tested. Charpy impact toughness was higher in the stir zone and heat affected zone than in the base metal. For higher microhardness values were found in the stir zone and heat affected zone than the base metal due to grain refinement and modification of the microstructures. As a result, improved mechanical properties compared to the basemore » metal were found in the weld zones of friction stir welded A516 Grade 70 steel.« less

  18. Nano-structure multilayer technology fabrication of high energy density capacitors for the power electronic building book

    SciTech Connect

    Barbee, T.W.; Johnson, G.W.; Wagner, A.V.

    1997-10-21

    Commercially available capacitors do not meet the specifications of the Power Electronic Building Block (PEBB) concept. We have applied our propriety nanostructure multilayer materials technology to the fabrication of high density capacitors designed to remove this impediment to PEBB progress. Our nanostructure multilayer capacitors will also be enabling technology in many industrial and military applications. Examples include transient suppression (snubber capacitors), resonant circuits, and DC filtering in PEBB modules. Additionally, weapon applications require compact energy storage for detonators and pulsed-power systems. Commercial applications run the gamut from computers to lighting to communications. Steady progress over the last five years has brought us to the threshold of commercial manufacturability. We have demonstrated a working dielectric energy density of > 11 J/cm3 in 20 nF devices designed for 1 kV operation.

  19. Properties of light-emitting diodes fabricated from self-assembled multilayer heterostructures of poly(p-pyridyl vinylene)

    NASA Astrophysics Data System (ADS)

    Onoda, Mitsuyoshi; Chuma, Akihiro; Nakayama, Hiroshi; Yamaue, Takahiro; Tada, Kazuya; Yoshino, Katsumi

    1997-08-01

    Heterostructure multilayer thin films of electroactive polymers such as protonated poly(p-pyridyl vinylene) (PHPyV) and sulphonated polyaniline (SPAn) have been fabricated via processes based on the spontaneous self-assembly of conjugated poly-ions on to a substrate. The heterostructure thin films formed from these polymers exhibited a perfectly linear relationship between the absorbance and the number of SPAn/PHPyV bilayers deposited. A greenish - yellow electroluminescent (EL) diode utilizing a SPAn/PHPyV multilayer thin film has been fabricated and the EL properties of this device are discussed. The EL emission of this device can be qualitatively interpreted in terms of radiative recombination of the singlet polaron exciton formed by the injection of electrons and holes. The EL intensity of this light-emitting diode is weak. This result is discussed in terms of the quenching centre of cationic sites on the PHPyV polymer's main chain at the heterojunction. The Stokes shift due to the absorption and emission of a phonon is clearly observed in the EL spectrum of this device. A small shift between the EL and PL spectra of SPAn/PHPyV is observed. It was assumed that the EL emission takes place in a narrow region at the interface whereas the PL emission probes the bulk of the film. The SPAn/PHPyV monolayer LED emits yellow light, but the SPAn/PHPyV multilayer LED emits greenish - yellow light and there is a slight shift between the two spectra of these devices. These results can be interpreted in terms of the effect of confinement of carriers in the superlattice structure constituting the SPAn/PHPyV multilayer system.

  20. Multilayer Coextrusion of Polymer Composites to Develop Organic Capacitors

    SciTech Connect

    Mondy, L.; Mrozek, R.; Rao, R.; Lenhart, J.; Bieg, L.; Spangler, S.; Stavig, M.; Schroeder, J.; Winter, M.; Diantonio, C.; Collins, R.

    2015-05-29

    Multilayer coextrusion is applied to produce a tape containing layers of alternating electrical properties to demonstrate the potential for using coextrusion to manufacture capacitors. To obtain the desired properties, we develop two filled polymer systems, one for conductive layers and one for dielectric layers. We describe numerical models used to help determine the material and processing parameters that impact processing and layer stability. These models help quantify the critical ratios of densities and viscosities of the two layers to maintain stable layers, as well as the effect of increasing the flow rate of one of the two materials. The conducting polymer is based on polystyrene filled with a blend of low-melting-point eutectic metal and nickel particulate filler, as described by Mrozek et al. (2010). The appropriate concentrations of fillers are determined by balancing measured conductivity with processability in a twin screw extruder. Based on results of the numerical models and estimates of the viscosity of emulsions and suspensions, a dielectric layer composed of polystyrene filled with barium titanate is formulated. Despite the fact that the density of the dielectric filler is less than the metallic filler of the conductive phase, as well as rheological measurements that later showed that the dielectric formulation is not an ideal match to the viscosity of the conductive material, the two materials can be successfully coextruded if the flow rates of the two materials are not identical. A measurable capacitance of the layered structure is obtained.

  1. Multilayer Coextrusion of Polymer Composites to Develop Organic Capacitors

    DOE PAGESBeta

    Mondy, L.; Mrozek, R.; Rao, R.; Lenhart, J.; Bieg, L.; Spangler, S.; Stavig, M.; Schroeder, J.; Winter, M.; Diantonio, C.; et al

    2015-05-29

    Multilayer coextrusion is applied to produce a tape containing layers of alternating electrical properties to demonstrate the potential for using coextrusion to manufacture capacitors. To obtain the desired properties, we develop two filled polymer systems, one for conductive layers and one for dielectric layers. We describe numerical models used to help determine the material and processing parameters that impact processing and layer stability. These models help quantify the critical ratios of densities and viscosities of the two layers to maintain stable layers, as well as the effect of increasing the flow rate of one of the two materials. The conductingmore » polymer is based on polystyrene filled with a blend of low-melting-point eutectic metal and nickel particulate filler, as described by Mrozek et al. (2010). The appropriate concentrations of fillers are determined by balancing measured conductivity with processability in a twin screw extruder. Based on results of the numerical models and estimates of the viscosity of emulsions and suspensions, a dielectric layer composed of polystyrene filled with barium titanate is formulated. Despite the fact that the density of the dielectric filler is less than the metallic filler of the conductive phase, as well as rheological measurements that later showed that the dielectric formulation is not an ideal match to the viscosity of the conductive material, the two materials can be successfully coextruded if the flow rates of the two materials are not identical. A measurable capacitance of the layered structure is obtained.« less

  2. Method for Fabricating Composite Structures Using Pultrusion Processing

    NASA Technical Reports Server (NTRS)

    Farley, Gary L. (Inventor)

    2000-01-01

    A method for fabricating composite structures at a low-cost, moderate-to-high production rate. A first embodiment of the method includes employing a continuous press forming fabrication process. A second embodiment of the method includes employing a pultrusion process for obtaining composite structures. The methods include coating yarns with matrix material, weaving the yarn into fabric to produce a continuous fabric supply and feeding multiple layers of net-shaped fabrics having optimally oriented fibers into a debulking tool to form an undebulked preform. The continuous press forming fabrication process includes partially debulking the preform, cutting the partially debulked preform and debulking the partially debulked preform to form a netshape. An electron-beam or similar technique then cures the structure. The pultrusion fabric process includes feeding the undebulked preform into a heated die and gradually debulking the undebulked preform. The undebulked preform in the heated die changes dimension until a desired cross-sectional dimension is achieved. This process further includes obtaining a net-shaped infiltrated uncured preform, cutting the uncured preform to a desired length and electronbeam curing (or similar technique) the uncured preform. These fabrication methods produce superior structures formed at higher production rates, resulting in lower cost and high structural performance.

  3. Method for Fabricating Composite Structures Using Pultrusion Processing

    NASA Technical Reports Server (NTRS)

    Farley, Gary L. (Inventor)

    2000-01-01

    A method for fabricating composite structures at a low-cost, moderate-to-high production rate. A first embodiment of the method includes employing a continuous press forming fabrication process. A second embodiment of the method includes employing a pultrusion process for obtaining composite structures. The methods include coating yarns with matrix material, weaving the yarn into fabric to produce a continuous fabric supply and feeding multiple layers of net-shaped fabrics having optimally oriented fibers into a debulking tool to form an undebulked preform. The continuous press forming fabrication process includes partially debulking the preform, cutting the partially debulked preform and debulking the partially debulked preform to form a net-shape. An electron-beam or similar technique then cures the structure. The pultrusion fabric process includes feeding the undebulked preform into a heated die and gradually debulking the undebulked preform. The undebulked preform in the heated die changes dimension until a desired cross-sectional dimension is achieved. This process further includes obtaining a net-shaped infiltrated uncured preform, cutting the uncured preform to a desired length and electron-beam curing (or similar technique) the uncured preform. These fabrication methods produce superior structures formed at higher production rates, resulting in lower cost and high structural performance.

  4. Method for Fabricating Composite Structures Using Continuous Press Forming

    NASA Technical Reports Server (NTRS)

    Farley, Gary L. (Inventor)

    1997-01-01

    A method for fabricating composite structures at a low-cost. moderate-to-high production rate. A first embodiment of the method includes employing a continuous press forming fabrication process. A second embodiment of the method includes employing a pultrusion process for obtaining composite structures. The methods include coating yarns with matrix material, weaving the yarn into fabric to produce a continuous fabric supply and feeding multiple layers of net-shaped fabrics having optimally oriented fibers into a debulking tool to form an undebulked preform. The continuous press forming fabrication process includes partially debulking the preform, cutting the partially debulked preform and debulking the partially debulked preform to form a net-shape. An electron-beam or similar technique then cures the structure. The pultrusion fabric process includes feeding the undebulked preform into a heated die and gradually debulking the undebulked preform. The undebulked preform in the heated die changes dimension until a desired cross-sectional dimension is achieved. This process further includes obtaining a net-shaped infiltrated uncured preform, cutting the uncured preform to a desired length and electron-beam curing (or similar technique) the uncured preform. These fabrication methods produce superior structures formed at higher production rates. resulting in lower cost and high structural performance.

  5. Organic-inorganic composites for THz device fabrication

    NASA Astrophysics Data System (ADS)

    Cai, B.; Ye, T. M.; Bo, G.; Wang, X. C.; Li, Y. Z.; Zhu, Y. M.; Sugihara, O.

    2016-02-01

    In this paper, several organic-inorganic composites were prepared for Terahertz (THz) devices fabrication. First, a two-layer structure was designed for femtosecond (fs) laser/THz radiation separation. The top layer was made by sintered 20-40 nm hollow quartz particles which can diffuse the incident fs laser thus decrease the power intensity. The bottom layer comprised of silicon 100 nm particles and cycle-olefine polymer (COP), by which the fs laser light can be greatly scattered and absorbed but THz radiation can propagate insusceptibly. With this two-layer structure a high efficient fs-laser/THz filter was fabricated successfully. Second, titania-polymer composites with a very high refractiveindex tunability and high transparency in the THz region were prepared. By controlling the blending ratio of the titania particle, a broad refractive-index tuning range from 1.5 to 3.1 was realized. Then, the composites were used to fabricate antireflective (AR) layers on a high-resistivity silicon (HR-Si) substrate. By utilizing the thermoplasticity of the titania- polymer composite, a graded-index structure was fabricated via a hot-embossing method. Because of the good refractive-index matching between the composite and the HR-Si substrate, a broadband AR layer was fabricated.

  6. The mechanical deformation mechanisms in knitted fabric composites

    SciTech Connect

    Kelay, M.S.; Bader, D.L.; Reed, P.E.

    1994-12-31

    Knitted fabric composites have certain advantages over woven composites, particularly in their ability to conform to complicated contours. As a consequence, they demonstrate inferior mechanical characteristics compared to woven materials as a direct result of the presence of bent fibers. Such a knitted fabric composite made from, for example, glass fibers in a polyurethane matrix, can be used as an orthopaedic splinting bandage for immobilizing fractures of the upper and lower limbs. Relatively little research has been reported on knitted fabric composites was initiated. It was observed that knit patterns, type of fiber, size of fibers used, size of loops, coatings and lay-up procedure were all variables that could affect the structure/property relationship of knitted fabric composites. Tensile testing with optical measurement of strain was performed on knitted substrate and coated bandages in both course and wale directions. Results indicated that the knitted fabrics function as link mechanisms at the microscopic level, with knitted loops straightening and bending before the individual elements of the knitted yarn take up significant load and material deformation. Theoretical modeling of the glass knit structure, in both course and wale directions, agrees well with experimental testing.

  7. Molecular Design of Strong SWNT/Polyelectrolyte Multilayers Composites

    NASA Astrophysics Data System (ADS)

    Kotov, Nicholas

    2003-03-01

    The mechanical failure of hybrid materials made from polymers and single wall carbon nanotubes (SWNT) is primarily attributed to poor matrix-SWNT connectivity and severe phase segregation. Both problems can be successfully mitigated when the SWNTcomposite is made following the protocol of layer-by-layer assembly. This deposition technique prevents phase segregation of the polymer/SWNT binary system, and after subsequent cross-linking, the nm-scale-uniform composite with SWNT loading as high as 50 wtmembranes delaminated from the substrate were found to be exceptionally strong with tensile strength approaches that of hard ceramics. Considering the light-weight nature of SWNT composites the prepared free-standing membranes can serve as unique components for a variety of long-life-time devices. The assembly process also affords preparation of aligned SWNT composites. Laminar flow adsorption shows gradual untangling of the nanotube agglomerates and the formation of parallel ribbons.

  8. Frequency control of sol–gel composite films fabricated by stencil printing for nondestructive testing applications

    NASA Astrophysics Data System (ADS)

    Kaneko, Tsukasa; Kibe, Taiga; Kimoto, Keisuke; Nishimura, Ryota; Kobayashi, Makiko

    2016-07-01

    Ultrasonic transducers made of sol–gel composites have been developed for nondestructive testing (NDT) applications in various industrial fields. Stencil printing of sol–gel composite films has been developed for the reduction of fabrication time and cost. However, it was necessary to develop low frequency (<10 MHz) ultrasonic transducers for inspecting industrial structures under severe high-temperature conditions, because high-frequency components suffer attenuation effect caused by high temperature. To realize this, increasing the thickness of Pb(Zr,Ti)O3 (PZT)/PZT films fabricated by stencil printing was attempted in this study. The samples were fabricated by single-layer stencil printing with a thick stencil mask and multilayer pure stencil printing with prespraying and postspraying. The film thicknesses were 150–185 µm, and the center frequencies of ultrasonic responses were 6.0–6.4 MHz. Throughout three thermal cycles of up to 370 K, the ultrasonic performance was stable, and the frequency characteristics were not markedly different from the beginning to the end of the test. Therefore, low-frequency ultrasonic transducers were successfully manufactured using a stencil-printing-based technique.

  9. Fabrication and evaluation of advanced titanium and composite structural panels

    NASA Technical Reports Server (NTRS)

    Bales, T. T.; Hoffman, E. L.; Payne, L.; Carter, A. L.

    1976-01-01

    Advanced manufacturing methods for titanium and composite material structures are being developed and evaluated. The focus for the manufacturing effort is the fabrication of full-scale structural panels which replace an existing shear panel on the upper wing surface of the NASA YF-12 aircraft. The program involves design, fabrication, ground testing, and Mach 3 flight service of full-scale structural panels and laboratory testing of representative structural element specimens.

  10. Dynamic characteristics of an axially polarized multilayer piezoelectric/elastic composite cylindrical transducer.

    PubMed

    Wang, Jianjun; Shi, Zhifei

    2013-10-01

    An analytical model of the dynamic characteristics of an axially polarized multilayer piezoelectric/elastic composite cylindrical transducer is proposed in this paper. Based on the plane stress assumption, the dynamic analytical solution of the transducer under an external harmonic voltage load is obtained, and the electric admittance is also derived analytically. Inherent properties of the transducer, such as resonance and anti-resonance frequencies, are presented and discussed. In addition, comparisons with other related investigations are also given, and good agreement is found. The present investigation is very helpful for the design of axially polarized multilayer piezoelectric/elastic composite cylindrical transducers, which can be used in applications related to ultrasonic and underwater sound waves. PMID:24081268

  11. The propagation of coupled Lamb waves in multilayered arbitrary anisotropic composite laminates

    NASA Astrophysics Data System (ADS)

    Cunfu, He; Hongye, Liu; Zenghua, Liu; Bin, Wu

    2013-12-01

    Based on linear three-dimensional elasticity theory, the wave equations of coupled Lamb waves in multilayered arbitrary anisotropic composite laminates are derived using a Legendre orthogonal polynomial approach. The elastodynamic solution for the propagation of coupled Lamb waves in composite plates is also presented to determine the characteristics of coupled Lamb waves. To verify the applicability and validity of the method, two cases of bi-layered plates formed with isotropic components and anisotropic components, respectively, are primarily manipulated for comparison with earlier known results. Next, the dispersion curves, displacements and stress distributions of Lamb waves in multilayered anisotropic laminates are calculated. The effects of coupling and fiber orientation on the characteristics of the Lamb waves are illustrated. The potential usefulness of the fundamental modes of the coupled Lamb waves is discussed in detail.

  12. Subwavelength imaging from a multilayered structure containing interleaved nonspherical metal-dielectric composites

    NASA Astrophysics Data System (ADS)

    Shi, Lihong; Gao, Lei

    2008-05-01

    A thin multilayered structure with interleaved nonspherical metal-dielectric composites slices and dielectric slices may be modeled as the metamaterial with anisotropic permittivity. The signs of diagonal elements of the permittivity tensor can be controlled by the particles’ shape, the volume fraction of metal particles, and the incidental wavelengths. To one’s interest, when the spheroidal nanoparticles are oblate in shape, the wavelength range in which components of the permittivity have different signs is widened, and the magnitude of optical absorption band becomes weak. Since both physical anisotropy and low absorption are helpful for improving the subwavelength image resolution, the multilayered structure containing metal-dielectric composite layer of nonspherical particles may be designed as a superlens device. In addition, the incident wavelength and the number of nanolayers are found to play crucial roles in enhancing the evanescent field performance too.

  13. Fabricating porous materials using interpenetrating inorganic-organic composite gels

    DOEpatents

    Seo, Dong-Kyun; Volosin, Alex

    2016-06-14

    Porous materials are fabricated using interpenetrating inorganic-organic composite gels. A mixture or precursor solution including an inorganic gel precursor, an organic polymer gel precursor, and a solvent is treated to form an inorganic wet gel including the organic polymer gel precursor and the solvent. The inorganic wet gel is then treated to form a composite wet gel including an organic polymer network in the body of the inorganic wet gel, producing an interpenetrating inorganic-organic composite gel. The composite wet gel is dried to form a composite material including the organic polymer network and an inorganic network component. The composite material can be treated further to form a porous composite material, a porous polymer or polymer composite, a porous metal oxide, and other porous materials.

  14. Method for fabricating composite carbon foam

    DOEpatents

    Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

    2001-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy.

  15. Structural and magnetic properties of Co-C composite films and Co/C multilayer films

    NASA Astrophysics Data System (ADS)

    Shi, J.; Azumi, M.; Nittono, O.

    CoC composite films and Co/C multilayer films have been prepared by a method incorporating ion beam sputtering and plasma chemical vapor deposition. It has been found that the structure and magnetic properties of both the Co-C composite and the Co/C multilayer films depend strongly on the substrate temperature during deposition. The Co-C composite film deposited at room temperature is amorphous, with relatively low saturation magnetization and coercivity. On the other hand, the film deposited at 250 °C is composed of fine Co crystallites separated by amorphous C or Co-C phase. As a result, both the saturation magnetization and coercivity are increased compared with the film deposited at room temperature. When deposited at room temperature, the Co/C multilayer film exhibits good periodicity, with a period of 70 nm (Co: 40 nm, C: 30 nm) and sharp and flat Co-C interfaces. High magnetization (602 emu/cm3) and low coercivity (1.6 Oe) are obtained for such a film. However, increasing the substrate temperature to 250 °C was found to be detrimental to the magnetic properties due to the formation of cobalt carbide at the Co-C interface.

  16. Interfacial reactions in titanium/SCS fiber composites during fabrication

    NASA Technical Reports Server (NTRS)

    Warrier, S. G.; Lin, R. Y.

    1993-01-01

    The objectrive of the study was to determine the effect of titanium concentration and different pyrocarbon fiber coatings on the morphology and the extent of fiber-matrix reactions in Ti/SiC composites fabricated by rapid infrared forming (RIF). It is found that the extent of fiber-matrix reactions in Ti/SiC composites fabricated by the RIF technique is noticeably affected by both an increase in Ti content and by the processing temperature. Uncoated SiC fibers extensively react with the titanium alloy matrix at 1200 C, whereas no reaction occurs when coated SiC fibers are used.

  17. Damage-Tolerant Composites Made By Stitching Carbon Fabrics

    NASA Technical Reports Server (NTRS)

    Dow, Marvin B.; Smith, Donald L.

    1992-01-01

    Work conducted at NASA Langley Research Center to investigate stitching combined with resin transfer molding to make composites more tolerant of damage and potentially cost competitive with metals. Composite materials tailored for damage tolerance by stitching layers of dry carbon fabric with closely spaced threads to provide reinforcement through thickness. Epoxy resin then infused into stitched preforms, and epoxy was cured. Various stitching patterns and thread materials evaluated by use of flat plate specimens. Also, blade-stiffened structural elements fabricated and tested. Stitched flat laminates showed outstanding damage tolerance, excellent compression strength in notched specimens, and acceptable fatigue behavior. Development of particular interest to aircraft and automotive industries.

  18. Finite element analysis of the stiffness of fabric reinforced composites

    NASA Technical Reports Server (NTRS)

    Foye, R. L.

    1992-01-01

    The objective of this work is the prediction of all three dimensional elastic moduli of textile fabric reinforced composites. The analysis is general enough for use with complex reinforcing geometries and capable of subsequent improvements. It places no restrictions on fabric microgeometry except that the unit cell be determinate and rectangular. The unit cell is divided into rectangular subcells in which the reinforcing geometries are easier to define and analyze. The analysis, based on inhomogeneous finite elements, is applied to a variety of weave, braid, and knit reinforced composites. Some of these predictions are correlated to test data.

  19. Fabrication of Ketjen black-polybenzoxazine superhydrophobic conductive composite coatings

    NASA Astrophysics Data System (ADS)

    Shen, Lie; Ding, Hongliang; Wang, Wen; Guo, Qipeng

    2013-03-01

    Superhydrophobic conductive Ketjen black-polybenzoxazine (KB-PBZ) composite coatings were prepared by a simple drop casting method with high static water contact angle (˜160°), low sliding angle (˜3°), and low sheet resistance (103 Ω/sq). The relationship between Ketjen black amounts and the structure and properties of the composite coatings was investigated. Under appropriate conditions, the composite coatings showed hierarchically structured roughness and possessed superhydrophobicity over the whole range of pH values. These coatings exhibited excellent thermal and environmental stability. Moreover, the superhydrophobic conductive composite coatings also can be obtained on various substrates such as wood, aluminum foil, paper, polyethylene terephthalate film and fabric.

  20. Fabrication of Carbon Nanotube - Chromium Carbide Composite Through Laser Sintering

    NASA Astrophysics Data System (ADS)

    Liu, Ze; Gao, Yibo; Liang, Fei; Wu, Benxin; Gou, Jihua; Detrois, Martin; Tin, Sammy; Yin, Ming; Nash, Philip; Tang, Xiaoduan; Wang, Xinwei

    2016-03-01

    Ceramics often have high hardness and strength, and good wear and corrosion resistance, and hence have many important applications, which, however, are often limited by their poor fracture toughness. Carbon nanotubes (CNTs) may enhance ceramic fracture toughness, but hot pressing (which is one typical approach of fabricating CNT-ceramic composites) is difficult to apply for applications that require localized heat input, such as fabricating composites as surface coatings. Laser beam may realize localized material sintering with little thermal effect on the surrounding regions. However, for the typical ceramics for hard coating applications (as listed in Ref.[1]), previous work on laser sintering of CNT-ceramic composites with mechanical property characterizations has been very limited. In this paper, research work has been reported on the fabrication and characterization of CNT-ceramic composites through laser sintering of mixtures of CNTs and chromium carbide powders. Under the studied conditions, it has been found that laser-sintered composites have a much higher hardness than that for plasma-sprayed composites reported in the literature. It has also been found that the composites obtained by laser sintering of CNTs and chromium carbide powder mixtures have a fracture toughness that is ~23 % higher than the material obtained by laser sintering of chromium carbide powders without CNTs.

  1. A blanket design, apparatus, and fabrication techniques for the mass production of multilayer insulation blankets for the Superconducting Super Collider

    SciTech Connect

    Gonczy, J.D.; Boroski, W.N.; Niemann, R.C.; Otavka, J.G.; Ruschman, M.K.; Schoo, C.J.

    1989-09-01

    The multilayer insulation (MLI) system for the Superconducting Super Collider (SSC) consists of full cryostat length assemblies of aluminized polyester film fabricated in the form of blankets and installed as blankets to the 4.5K cold mass and the 20K and 80K thermal radiation shields. Approximately 40,000 MLI blankets will be required in the 10,000 cryogenic devices comprising the SSC accelerator. Each blanket is nearly 17 meters long and 1.8 meters wide. This paper reports the blanket design, an apparatus, and the fabrication method used to mass produce pre-fabricated MLI blankets. Incorporated in the blanket design are techniques which automate quality control during installation of the MLI blankets in the SSC cryostat. The apparatus and blanket fabrication method insure consistency in the mass produced blankets by providing positive control of the dimensional parameters which contribute to the thermal performance of the MLI blanket. By virtue of the fabrication process, the MLI blankets have inherent features of dimensional stability three-dimensional uniformity, controlled layer density, layer-to-layer registration, interlayer cleanliness, and interlayer material to accommodate thermal contraction differences. 11 refs., 6 figs., 1 tab.

  2. Fabrication and characterization of micro-structures created by direct laser writing in multi-layered chalcogenide glasses

    NASA Astrophysics Data System (ADS)

    Schwarz, Casey M.; Grabill, Chris N.; Gleason, Benn; Richardson, Gerald D.; Lewis, Anna M.; Vyas, Aadit; Rivero-Baleine, Clara; Richardson, Kathleen A.; Pogrebnyakov, Alexej; Mayer, Theresa S.; Kuebler, Stephen M.

    2015-03-01

    Arsenic trisulfide (As2S3) is a chalcogenide (ChG) material with excellent infrared (IR) transparency (620 nm to 11 μm), low phonon energies, and large nonlinear refractive indices. These properties directly relate to commercial and industrial applications including sensors, photonic waveguides, and acousto-optics. Multi-photon exposure can be used to photopattern thermally deposited As2S3 ChG glassy films of molecular clusters. Immersing the photo-patterned cross-linked material into a polar-solvent removes the unexposed material leaving behind a structure that is a negative-tone replica of the photo-pattern. Nano-structure arrays that were photo-patterned in single-layered As2S3 films through multi-photon direct laser writing (DLW) resulted in the production of nano-beads as a consequence of a standing wave effect. To overcome this effect, an anti-reflective (AR) layer of arsenic triselenide (As2Se3) was thermally deposited between the silicon substrate and the As2S3 layer, creating a multi-layered film. The chemical composition of the unexposed and photo-exposed multi-layered film was examined through Raman spectroscopy. Nano-structure arrays were photopatterned in the multi-layered film and the resulting structure, morphology, and chemical composition were characterized, compared to results from the single-layered film, and correlated with the conditions of the thermal deposition, patterned irradiation, and etch processing.

  3. Sialon ceramic compositions and methods of fabrication

    DOEpatents

    O'Brien, Michael H.; Park, Blair H.

    1994-01-01

    A method of fabricating a SiAlON ceramic body includes: a) combining quantities of Si.sub.3 N.sub.4, Al.sub.2 O.sub.3 and CeO.sub.2 to produce a mixture; b) forming the mixture into a desired body shape; c) heating the body to a densification temperature of from about 1550.degree. C. to about 1850.degree. C.; c) maintaining the body at the densification temperature for a period of time effective to densify the body; d) cooling the densified body to a devitrification temperature of from about 1200.degree. C. to about 1400.degree. C.; and e) maintaining the densified body at the devitrification temperature for a period of time effective to produce a .beta.'-SiAlON crystalline phase in the body having elemental or compound form Ce incorporated in the .beta.'-SiAlON crystalline phase. Further, a SiAlON ceramic body comprises: a) an amorphous phase; and b) a crystalline phase, the crystalline phase comprising .beta.'-SiAlON having lattice substituted elemental or compound form Ce.

  4. Chiral braided and woven composites: design, fabrication, and electromagnetic characterization

    NASA Astrophysics Data System (ADS)

    Wheeland, Sara; Bayatpur, Farhad; Amirkhizi, Alireza V.; Nemat-Nasser, Sia

    2011-04-01

    This work presents a new chiral composite composed of copper wires braided with Kevlar and nylon to form conductive coils integrated among structural fiber. To create a fabric, these braids were woven with plain Kevlar fiber. This yielded a composite with all coils possessing the same handedness, producing a chiral material. The electromagnetic response of this fabric was first simulated using a finite element full-wave simulation. For the electromagnetic measurement, the sample was placed between two lens-horn antennas connected to a Vector Network Analyzer. The frequency response of the sample was scanned between 5.5 and 8GHz. The measured scattering parameters were then compared to those of the simulated model. The measured parameters agreed well with the simulation results, showing a considerable chirality within the measured frequency band. The new composite combines the strength and durability of traditional composites with an electromagnetic design to create a multifunctional material.

  5. Process for fabricating composite material having high thermal conductivity

    DOEpatents

    Colella, Nicholas J.; Davidson, Howard L.; Kerns, John A.; Makowiecki, Daniel M.

    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.

  6. Fabrication and characterization of AZ91/CNT magnesium matrix composites

    NASA Astrophysics Data System (ADS)

    Park, Yong-Ha; Park, Yong-Ho; Park, Ik-Min; Oak, Jeong-jung; Kimura, Hisamichi; Cho, Kyung-Mox

    2008-12-01

    Carbon Nano Tube (CNT) reinforced AZ91 metal matrix composites (MMC) were fabricated by the squeeze infiltrated method. Properties of magnesium alloys have been improved by impurity reduction, surface treatment and alloy design, and thus the usage for the magnesium alloys has been extended recently. However there still remain barriers for the adaption of magnesium alloys for engineering materials. In this study, we report light-weight, high strength heat resistant magnesium matrix composites. Microstructural study and tensile test were performed for the squeeze infiltrated magnesium matrix composites. The wear properties were characterized and the possibility for the application to automotive power train and engine parts was investigated. It was found that the squeeze infiltration technique is a proper method to fabricate magnesium matrix composites reducing casting defects such as pores and matrix/reinforcement interface separation etc. Improved tensile and mechanical properties were obtained with CNT reinforcing magnesium alloys

  7. Mass Conservation in Modeling Moisture Diffusion in Multi-Layer Carbon Composite Structures

    NASA Technical Reports Server (NTRS)

    Nurge, Mark A.; Youngquist, Robert C.; Starr, Stanley O.

    2009-01-01

    Moisture diffusion in multi-layer carbon composite structures is difficult to model using finite difference methods due to the discontinuity in concentrations between adjacent layers of differing materials. Applying a mass conserving approach at these boundaries proved to be effective at accurately predicting moisture uptake for a sample exposed to a fixed temperature and relative humidity. Details of the model developed are presented and compared with actual moisture uptake data gathered over 130 days from a graphite epoxy composite sandwich coupon with a Rohacell foam core.

  8. Design and fabrication of a high-density multilayer metal-insulator-metal capacitor based on selective etching

    SciTech Connect

    Tseng, VFG; Xie, H

    2013-02-06

    This paper presents a novel and cost-effective method for fabricating high-density multilayer metal-insulator-metal (MIM) integrated capacitors. To eliminate the usage of numerous photolithography steps when parallel stacking multiple capacitors layers, a unique process has been developed based on depositing the MIM layers onto a substrate with two protruding pillars, polishing down the pillars to expose the multilayer cross sections and then selectively etching the metal layers on each pillar to form the alternating capacitor plate electrodes. For demonstration purpose, only capacitors with two dielectric layers were fabricated, and the measurement results were verified by a compact analytical model together with finite element simulations. With 200 nm thick silicon nitride/oxide dielectric layers, a capacitance density of 0.6 fF mu m(-2) was achieved, which can be easily increased by scaling down the layer thicknesses and/or stacking more layers. A low equivalent series resistance (ESR) of 300-700 m Omega was measured, and the self-resonance frequency was above measurement limits (> 100 MHz). Further design optimization shows that the ESR can be reduced to below 80 m Omega, while the operation frequency extended to above 2.6 GHz.

  9. A biomimetic multilayer nanofiber fabric fabricated by electrospinning and textile technology from polylactic acid and Tussah silk fibroin as a scaffold for bone tissue engineering.

    PubMed

    Shao, Weili; He, Jianxin; Han, Qiming; Sang, Feng; Wang, Qian; Chen, Li; Cui, Shizhong; Ding, Bin

    2016-10-01

    To engineer bone tissue, a scaffold with good biological properties should be provided to approximate the hierarchical structure of collagen fibrils in natural bone. In this study, we fabricated a novel scaffold consisting of multilayer nanofiber fabrics (MLNFFs) by weaving nanofiber yarns of polylactic acid (PLA) and Tussah silk fibroin (TSF). The yarns were fabricated by electrospinning, and we found that spinnability, as well as the mechanical properties of the resulting scaffold, was determined by the ratio between polylactic acid and Tussah silk fibroin. In particular, a 9:1 mixture can be spun continuously into nanofiber yarns with narrow diameter distribution and good mechanical properties. Accordingly, woven scaffolds based on this mixture had excellent mechanical properties, with Young's modulus 417.65MPa and tensile strength 180.36MPa. For nonwoven scaffolds fabricated from the same materials, the Young's modulus and tensile strength were 2- and 4-fold lower, respectively. Woven scaffolds also supported adhesion and proliferation of mouse mesenchymal stem cells, and promoted biomineralization via alkaline phosphatase and mineral deposition. Finally, the scaffolds significantly enhanced the formation of new bone in damaged femoral condyle in rabbits. Thus, the scaffolds are potentially suitable for bone tissue engineering because of biomimetic architecture, excellent mechanical properties, and good biocompatibility. PMID:27287159

  10. Mechanically fastened joints in woven fabric composites

    NASA Technical Reports Server (NTRS)

    Wilson, D. W.; Bozarth, M. J.; Pipes, R. B.

    1983-01-01

    Strength analysis for composite bolted joints involves the mating of a stress analysis with an appropriate mode specific failure criterion for each of the primary failure modes. The stress analysis and failure criteria are independent of each other and can be manipulated separately in order to optimize the strength analysis package formed by their coupling. Material properties tests were conducted on rubber toughened graphite-epoxy material to measure the basic strength and stiffness in the warp and fill directions and in shear. Test matrices are summarized for investigations of laminate configuration, stacking sequence, fastener diameter, edge distance, fastener half spacing, laminate thickness, and fastener torque. A three dimensional finite element analysis computer program was written and failure criteria for net tension, shearout, and bearing were determined.

  11. Processes for fabricating composite reinforced material

    DOEpatents

    Seals, Roland D.; Ripley, Edward B.; Ludtka, Gerard M.

    2015-11-24

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  12. Self-healing multilayer polyelectrolyte composite film with chitosan and poly(acrylic acid).

    PubMed

    Zhu, Yanxi; Xuan, Hongyun; Ren, Jiaoyu; Ge, Liqin

    2015-11-21

    If self-healing materials can be prepared via simple technology and methods using nontoxic materials, this would be a great step forward in the creation of environmentally friendly self-healing materials. In this paper, the specific structural parameters of the various hydrogen bonds between chitosan (CS) and polyacrylic acid (PAA) were calculated. Then, multilayer polyelectrolyte films were fabricated with CS and PAA based on layer-by-layer (LbL) self-assembly technology at different pH values. The possible influence of pH on the (CS/PAA) × 30 multilayer polyelectrolyte film was investigated. The results show that the interactions between CS and PAA, swelling capacity, microstructure, wettability, and self-healing ability are all governed by the pH of the CS solution. When the pH value of the CS solution is 3.0, the prepared multilayer polyelectrolyte film (CS3.0/PAA2.8) × 30 has fine-tuned interactions, a network-like structure, good swelling ability, good hydrophilicity, and excellent self-healing ability. This promises to greatly widen the future applications of environmentally friendly materials and bio-materials. PMID:26364567

  13. Solid freeform fabrication of highly loaded composite materials

    NASA Astrophysics Data System (ADS)

    Souvignier, Chad William

    Composites are known for their unique blend of modulus, strength, and toughness. This study focuses on two types of composites; organic-inorganic hybrids and the mineralization of highly swollen polymer gels. Both of these composite systems mimic the biological process of composite formation, known as biomineralization. Biomineralization allows for the control of the precipitating phase through an interaction with the organic matrix. This allows higher volume fractions of inorganic material than can be achieved by many traditional processing techniques. Solid freeform fabrication is a processing method that builds materials by the sequential addition of thin layers. As long as the material can easily be converted from a liquid to a solid, it should be amenable for this processing technique. Freeform fabrication has three distinctions from traditional processing techniques that may enable the formation of composite materials with improved mechanical properties. These are the sequential addition of layers, which allows a layer by layer influence of chemistry, the ability to form complex geometries, and finally, extrusion freeform fabrication has been shown to align fibers due to the extrusion of the slurry through a needle. Cracking and shrinkage still play a major role in forming solid parts. The use of an open mesh structure in combination with proper materials selection allowed the formation of highly loaded composite materials without cracking. The modulus values of these materials ranged from 0.1 GPa to 6.0 GPa. The mechanical properties of these materials were modeled.

  14. Thermomechanical postbuckling of multilayered composite panels with cutouts

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Peters, Jeanne M.; Starnes, James H., Jr.

    1995-01-01

    The results of a study of the detailed thermomechanical postbuckling response characteristics of flat unstiffened composite panels with central circular cutouts are presented. The panels are subjected to combined temperature changes and applied edge loading (or edge displacements). The analysis is based on a first-order shear deformation plate theory. A mixed formulation is used with the fundamental unknowns consisting of the generalized displacements and the stress resultants of the plate. The postbuckling displacements, transverse shear stresses, transverse shear strain energy density, and their sensitivity coefficients are evaluated. The sensitivity coefficients measure the sensitivity of the post-buckling response to variations in the different lamination and material parameters of the panel. Numerical results are presented showing the effects of the variations in the hole diameter, laminate stacking sequence, fiber orientation, and aspect ratio of the panel on the thermomechanical postbuckling response and its sensitivity to changes in panel parameters.

  15. Thermomechanical buckling of multilayered composite panels with cutouts

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Starnes, James H., Jr.; Peters, Jeanne M.

    1994-01-01

    A study is made of the thermomechanical buckling of flat unstiffened composite panels with central circular cutouts. The panels are subjected to combined temperature changes and applied edge loading (or edge displacements). The analysis is based on a first-order shear deformation plate theory. A mixed formulation is used with the fundamental unknowns consisting of the generalized displacements and the stress resultants of the plate. Both the stability boundary and the sensitivity coefficients are evaluated. The sensitivity coefficients measure the sensitivity of the buckling response to variations in the different lamination and material parameters of the panel. Numerical results are presented showing the effects of the variations in the hole diameter, laminate stacking sequence, fiber orientation, and aspect ratio of the panel on the thermomechanical buckling response and its sensitivity coefficients.

  16. Thermomechanical buckling of multilayered composite panels with cutouts

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Starnes, James H., Jr.; Peters, Jeanne M.

    1993-01-01

    A study is made of the thermomechanical buckling of flat unstiffened composite panels with central circular cutouts. The panels are subjected to combined temperature changes and applied edge loading (or edge displacements). The analysis is based on a first-order shear deformation plate theory. A mixed formulation is used with the fundamental unknowns consisting of the generalized displacements and the stress resultants of the plate. Both the stability boundary and the sensitivity coefficients are evaluated. The sensitivity coefficients measure the sensitivity of the buckling response to variations in the different lamination and material parameters of the panel. Numerical results are presented showing the effects of the variations in the hole diameter, laminate stacking sequence, fiber orientation, and aspect ratio of the panel on the thermomechanical buckling response and its sensitivity coefficients.

  17. Finite element buckling and postbuckling solutions for multilayered composite panels

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Peters, Jeanne M.

    1995-01-01

    A study is made of the buckling and postbuckling responses of flat, unstiffened composite panels subjected to various combinations of mechanical and thermal loads. The analysis is based on a first-order shear deformation von Karman-type plate theory. A mixed formulation is used with the fundamental unknowns consisting of the strain components, stress resultants and the generalized displacements of the plate. The stability boundary, postbuckling response and the sensitivity coefficients are evaluated. The sensitivity coefficients measure the sensitivity of the buckling and postbuckling responses to variations in the different lamination and material parameters of the panel. Numerical results are presented for both solid panels and panels with central circular cutouts. The results show the effects of the variations in the fiber orientation angels, aspect ratio of the panel, and the hole diameter (for panels with cutouts) on the stability boundary, postbuckling response and sensitivity coefficients.

  18. Multilayered Glass Fibre-reinforced Composites In Rotational Moulding

    NASA Astrophysics Data System (ADS)

    Chang, W. C.; Harkin-Jones, E.; Kearns, M.; McCourt, M.

    2011-05-01

    The potential of multiple layer fibre-reinforced mouldings is of growing interest to the rotational moulding industry because of their cost/performance ratio. The particular problem that arises when using reinforcements in this process relate to the fact that the process is low shear and good mixing of resin and reinforcement is not optimum under those conditions. There is also a problem of the larger/heavier reinforcing agents segregating out of the powder to lay up on the inner part surface. In this study, short glass fibres were incorporated and distributed into a polymer matrix to produce fibre-reinforced polymer composites using the rotational moulding process and characterised in terms of morphology and mechanical properties.

  19. Freeform fabrication of polymer-matrix composite structures

    SciTech Connect

    Kaufman, S.G.; Spletzer, B.L.; Guess, T.L.

    1997-05-01

    The authors have developed, prototyped, and demonstrated the feasibility of a novel robotic technique for rapid fabrication of composite structures. Its chief innovation is that, unlike all other available fabrication methods, it does not require a mold. Instead, the structure is built patch by patch, using a rapidly reconfigurable forming surface, and a robot to position the evolving part. Both of these components are programmable, so only the control software needs to be changed to produce a new shape. Hence it should be possible to automatically program the system to produce a shape directly from an electronic model of it. It is therefore likely that the method will enable faster and less expensive fabrication of composites.

  20. Fabrication of Composite Combustion Chamber/Nozzle for Fastrac Engine

    NASA Technical Reports Server (NTRS)

    Lawerence, T.; Beshears, R.; Burlingame, S.; Peters, W.; Prince, M.; Suits, M.; Tillery, S.; Burns, L.; Kovach, M.; Roberts, K.; Clinton, R. G., Jr. (Technical Monitor)

    2000-01-01

    The Fastrac Engine developed by the Marshall Space Flight Center for the X-34 vehicle began as a low cost engine development program for a small booster system. One of the key components to reducing the engine cost was the development of an inexpensive combustion chamber/nozzle. Fabrication of a regeneratively cooled thrust chamber and nozzle was considered too expensive and time consuming. In looking for an alternate design concept, the Space Shuttle's Reusable Solid Rocket Motor Project provided an extensive background with ablative composite materials in a combustion environment. An integral combustion chamber/nozzle was designed and fabricated with a silica/phenolic ablative liner and a carbon/epoxy structural overwrap. This paper describes the fabrication process and developmental hurdles overcome for the Fastrac engine one-piece composite combustion chamber/nozzle.

  1. Fabrication of Composite Combustion Chamber/Nozzle for Fastrac Engine

    NASA Technical Reports Server (NTRS)

    Lawrence, T.; Beshears, R.; Burlingame, S.; Peters, W.; Prince, M.; Suits, M.; Tillery, S.; Burns, L.; Kovach, M.; Roberts, K.

    2001-01-01

    The Fastrac Engine developed by the Marshall Space Flight Center for the X-34 vehicle began as a low cost engine development program for a small booster system. One of the key components to reducing the engine cost was the development of an inexpensive combustion chamber/nozzle. Fabrication of a regeneratively cooled thrust chamber and nozzle was considered too expensive and time consuming. In looking for an alternate design concept, the Space Shuttle's Reusable Solid Rocket Motor Project provided an extensive background with ablative composite materials in a combustion environment. An integral combustion chamber/nozzle was designed and fabricated with a silica/phenolic ablative liner and a carbon/epoxy structural overwrap. This paper describes the fabrication process and developmental hurdles overcome for the Fastrac engine one-piece composite combustion chamber/nozzle.

  2. Using template/hotwire cutting to demonstrate moldless composite fabrication

    NASA Technical Reports Server (NTRS)

    Coleman, J. Mario

    1990-01-01

    The objective of this experiment is to provide a simple, inexpensive composite fabrication technique which can be easily performed with a minimum of equipment and facilities. This process eliminates expensive female molds and uses only male molds which are easily formed from foam blocks. Once the mold is shaped, it is covered with fiberglass and becomes a structural component of the product.

  3. Fabrication and testing of prestressed composite rotor blade spar specimens

    NASA Technical Reports Server (NTRS)

    Gleich, D.

    1974-01-01

    Prestressed composite spar specimens were fabricated and evaluated by crack propagation and ballistic penetration tests. The crack propagation tests on flawed specimens showed that the prestressed composite spar construction significantly suppresses crack growth. Damage from three high velocity 30 caliber projectile hits was confined to three small holes in the ballistic test specimen. No fragmentation or crack propagation was observed indicating good ballistic damage resistance. Rotor attachment approaches and improved structural performance configurations were identified. Design theory was verified by tests. The prestressed composite spar configuration consisted of a compressively prestressed high strength ARDEFORM 301 stainless steel liner overwrapped with pretensioned S-994 fiberglass.

  4. 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,…

  5. Nano-fabricated superconducting radio-frequency composites, method for producing nano-fabricated superconducting rf composites

    DOEpatents

    Norem, James H.; Pellin, Michael J.

    2013-06-11

    Superconducting rf is limited by a wide range of failure mechanisms inherent in the typical manufacture methods. This invention provides a method for fabricating superconducting rf structures comprising coating the structures with single atomic-layer thick films of alternating chemical composition. Also provided is a cavity defining the invented laminate structure.

  6. Development and fabrication of bismaleimide-graphite composites

    NASA Technical Reports Server (NTRS)

    Stenzenberger, H.; Herzog, M.; Roemer, W.; Scheiblich, R.

    1979-01-01

    The successful fabrication of high temperature resistant composites depends mainly on the processability of the resin binder matrix. For two new bismaleimide type resins the processing of graphite fabric prepregs to composites is described. One resin coded M 751 has to be processed from N-Methylpyrrolidone, the other resin evaluated is a so-called hot melt solvent-less system. Commercial T300/3000 Graphite fabrics were used as reinforcement. The M 751 - Resin is a press grade material and laminates are therefore moulded in high pressure conditions (400 N/sq cm). The solvent-less resin system H 795 is an autoclave grade material and can be cured at 40 N/sq cm. The cure cycles for both the press grade and the autoclave grade material (Fiberite W 143 fabric prepregs) are provided and the mechanical properties of laminates at low (23 C) and high (232 C) temperatures were measured. For comparison, the neat resin flexural properties are also presented. The water absorption for the neat resins and the graphite fabric laminates after a 1000 hour period was evaluated.

  7. Ultrasonic detection and identification of fabrication defects in composites

    NASA Technical Reports Server (NTRS)

    Long, Edward R., Jr.; Kullerd, Susan M.; Johnston, Patrick H.; Madaras, Eric I.

    1991-01-01

    Methods for deliberate fabrication of porosity into carbon/epoxy composite panels and the influence of three-dimensional stitching on the detection of porosity were investigated. Two methods of introducing porosity were investigated. Porosity was simulated by inclusion of glass microspheres, and a more realistic form of porosity was introduced by using low pressure during consolidation. The panels were ultrasonically scanned and the frequency slope of the ultrasonic attenuation coefficient was used to evaluate the two forms of porosity. The influence of stitching on the detection of porosity was studied using panels which were resin transfer molded from stitched plies of knitted carbon fabric and epoxy resin.

  8. Net-Shape Tailored Fabrics For Complex Composite Structures

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    1995-01-01

    Proposed novel looms used to make fabric preforms for complex structural elements, both stiffening elements and skin, from continuous fiber-reinforced composite material. Components of looms include custom reed and differential fabric takeup system. Structural parts made best explained by reference to curved "I" cross-section frame. Technology not limited to these fiber orientations or geometry; fiber angles, frame radius of curvature, frame height, and flange width changed along length of structure. Weaving technology equally applicable to structural skins, such as wing of fuselage skins.

  9. Fabrication of an Electrically-Resistive, Varistor-Polymer Composite

    PubMed Central

    Ahmad, Mansor Bin; Fatehi, Asma; Zakaria, Azmi; Mahmud, Shahrom; Mohammadi, Sanaz A.

    2012-01-01

    This study focuses on the fabrication and electrical characterization of a polymer composite based on nano-sized varistor powder. The polymer composite was fabricated by the melt-blending method. The developed nano-composite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FeSEM), and energy-dispersive X-ray spectroscopy (EDAX). The XRD pattern revealed the crystallinity of the composite. The XRD study also showed the presence of secondary phases due to the substitution of zinc by other cations, such as bismuth and manganese. The TEM picture of the sample revealed the distribution of the spherical, nano-sized, filler particles throughout the matrix, which were in the 10–50 nm range with an average of approximately 11 nm. The presence of a bismuth-rich phase and a ZnO matrix phase in the ZnO-based varistor powder was confirmed by FeSEM images and EDX spectra. From the current-voltage curves, the non-linear coefficient of the varistor polymer composite with 70 wt% of nano filler was 3.57, and its electrical resistivity after the onset point was 861 KΩ. The non-linear coefficient was 1.11 in the sample with 100 wt% polymer content. Thus, it was concluded that the composites established a better electrical non-linearity at higher filler amounts due to the nano-metric structure and closer particle linkages. PMID:23443085

  10. Steady-state heat conduction in multilayered composite plates and shells

    NASA Technical Reports Server (NTRS)

    Noor, A. K.; Burton, W. S.

    1991-01-01

    A study is made of a predictor-corrector procedure for the accurate determination of the temperature and heat flux distributions in thick multilayered composite plates and shells. A linear through-the-thickness temperature distribution is used in the predictor phase. The functional dependence of temperature on the thickness coordinate is then calculated a posteriori and used in the corrector phase. Extensive numerical results are presented for linear steady-state heat conduction problems, showing the effects of variation in the geometric and lamination parameters on the accuracy of the thermal response predictions of the predictor-corrector approach. Both antisymmetrically laminated anisotropic plates and multilayered orthotropic cylinders are considered. The solutions are assumed to be periodic in the surface coordinates. For each problem the standard of comparison is taken to be the analytic three-dimensional solution based on treating each layer as a homogeneous anisotropic medium. The potential of the predictor-corrector approach for predicting the thermal response of multilayered plates and shells with complicated geometry is discussed.

  11. Optical properties of organic films, multilayers and plasmonic metal-organic waveguides fabricated by organic molecular beam deposition

    NASA Astrophysics Data System (ADS)

    Wickremasinghe, Niranjala D.

    In this thesis, the optical properties of tris (8-hydroxyquinoline) aluminum (Alq3) and 3,5,9,10-perylentetracarboxylic dianhydride (PTCDA) organic films, PTCDA/ Alq3 multilayers and plasmonic Alq3 -metal waveguides are investigated. The organic films and heterostructures used for this work were fabricated by organic molecular beam deposition (OMBD). We investigated the quenching of the light emission in Alq3 films grown on a Si substrate as a function of cw laser excitation intensity at varying temperatures from 15 to 300 K. The saturation of the singlet-singlet annihilation coefficient was measured with spectrally-integrated (SI) photoluminescence (PL) using a photodiode. The bimolecular quenching coefficient was further studied with time-resolved (TR) PL as a function of 100 fs pulse fluences. The PL quenching is attributed to the annihilation of trapped excitons at Alq3 nanocrystal grain boundaries. The saturation is explained by the limited density of available trapping states at the grain boundaries. Our interpretation is supported by structural investigations of ultrathin Alq3 films with atomic force microscopy (AFM), scanning electron microscopy (SEM) and by comparing the experimental data with calculations using a coupled rate equation model. The wavelength dispersion of the refractive indices of PTCDA and Alq 3 layers and of PTCDA/Alq3 multilayer waveguides grown on Pyrex substrates was investigated. The m-line technique, an evanescent prism coupling technique, was used to determine the layers' thickness and the in-plane (TE modes) and normal (TM modes) refractive indices. The potential for controlling the refractive index dispersion and anisotropy by tailored organic multilayer waveguides is discussed.

  12. Fabrication of Composite Material Using Gettou Fiber by Injection Molding

    NASA Astrophysics Data System (ADS)

    Setsuda, Roy; Fukumoto, Isao; Kanda, Yasuyuki

    This study investigated the mechanical properties of composite using gettou (shell ginger) fiber as reinforcement fabricated from injection molding. Gettou fiber is a natural fiber made from gettou, a subtropical plant that is largely abundant in Okinawa, Japan. We used the stem part of gettou plant and made the gettou fiber by crushing the stem. The composite using gettou fiber contributed to low shrinkage ratio, high bending strength and high flexural modulus. The mechanical strength of composite using long gettou fiber showed higher value than composite using short gettou fiber. Next, because gettou is particularly known for its anti-mold characteristic, we investigated the characteristic in gettou plastic composite. The composite was tested against two molds: aspergillius niger and penicillium funiculosum. The 60% gettou fiber plastic composite was found to satisfy the JISZ2801 criterion. Finally, in order to predict the flexural modulus of composite using gettou fiber by Halpin-Tsai equation, the tensile elastic modulus of single gettou fiber was measured. The tendency of the experimental results of composite using gettou fiber was in good agreement with Halpin-Tsai equation.

  13. Nonlinear analysis for high-temperature multilayered fiber composite structures. M.S. Thesis; [turbine blades

    NASA Technical Reports Server (NTRS)

    Hopkins, D. A.

    1984-01-01

    A unique upward-integrated top-down-structured approach is presented for nonlinear analysis of high-temperature multilayered fiber composite structures. Based on this approach, a special purpose computer code was developed (nonlinear COBSTRAN) which is specifically tailored for the nonlinear analysis of tungsten-fiber-reinforced superalloy (TFRS) composite turbine blade/vane components of gas turbine engines. Special features of this computational capability include accounting of; micro- and macro-heterogeneity, nonlinear (stess-temperature-time dependent) and anisotropic material behavior, and fiber degradation. A demonstration problem is presented to mainfest the utility of the upward-integrated top-down-structured approach, in general, and to illustrate the present capability represented by the nonlinear COBSTRAN code. Preliminary results indicate that nonlinear COBSTRAN provides the means for relating the local nonlinear and anisotropic material behavior of the composite constituents to the global response of the turbine blade/vane structure.

  14. Ceramic matrix composite article and process of fabricating a ceramic matrix composite article

    DOEpatents

    Cairo, Ronald Robert; DiMascio, Paul Stephen; Parolini, Jason Robert

    2016-01-12

    A ceramic matrix composite article and a process of fabricating a ceramic matrix composite are disclosed. The ceramic matrix composite article includes a matrix distribution pattern formed by a manifold and ceramic matrix composite plies laid up on the matrix distribution pattern, includes the manifold, or a combination thereof. The manifold includes one or more matrix distribution channels operably connected to a delivery interface, the delivery interface configured for providing matrix material to one or more of the ceramic matrix composite plies. The process includes providing the manifold, forming the matrix distribution pattern by transporting the matrix material through the manifold, and contacting the ceramic matrix composite plies with the matrix material.

  15. Numerical simulation of shock initiation of Ni/Al multilayered composites

    SciTech Connect

    Sraj, Ihab; Knio, Omar M.; Specht, Paul E.; Thadhani, Naresh N.; Weihs, Timothy P.

    2014-01-14

    The initiation of chemical reaction in cold-rolled Ni/Al multilayered composites by shock compression is investigated numerically. A simplified approach is adopted that exploits the disparity between the reaction and shock loading timescales. The impact of shock compression is modeled using CTH simulations that yield pressure, strain, and temperature distributions within the composites due to the shock propagation. The resulting temperature distribution is then used as initial condition to simulate the evolution of the subsequent shock-induced mixing and chemical reaction. To this end, a reduced reaction model is used that expresses the local atomic mixing and heat release rates in terms of an evolution equation for a dimensionless time scale reflecting the age of the mixed layer. The computations are used to assess the effect of bilayer thickness on the reaction, as well as the impact of shock velocity and orientation with respect to the layering. Computed results indicate that initiation and evolution of the reaction are substantially affected by both the shock velocity and the bilayer thickness. In particular, at low impact velocity, Ni/Al multilayered composites with thick bilayers react completely in 100 ms while at high impact velocity and thin bilayers, reaction time was less than 100 μs. Quantitative trends for the dependence of the reaction time on the shock velocity are also determined, for different bilayer thickness and shock orientation.

  16. Fiber/matrix interfaces for SiC/SiC composites: Multilayer SiC coatings

    SciTech Connect

    Halverson, H.; Curtin, W.A.

    1996-08-01

    Tensile tests have been performed on composites of CVI SiC matrix reinforced with 2-d Nicalon fiber cloth, with either pyrolitic carbon or multilayer CVD SiC coatings [Hypertherm High-Temperature Composites Inc., Huntington Beach, CA.] on the fibers. To investigate the role played by the different interfaces, several types of measurements are made on each sample: (i) unload-reload hysteresis loops, and (ii) acoustic emission. The pyrolitic carbon and multilayer SiC coated materials are remarkably similar in overall mechanical responses. These results demonstrate that low-modulus, or compliant, interface coatings are not necessary for good composite performance, and that complex, hierarchical coating structures may possibly yield enhanced high-temperature performance. Analysis of the unload/reload hysteresis loops also indicates that the usual {open_quotes}proportional limit{close_quotes} stress is actually slightly below the stress at which the 0{degrees} load-bearing fibers/matrix interfaces slide and are exposed to atmosphere.

  17. Intumescent all-polymer multilayer nanocoating capable of extinguishing flame on fabric

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton fabric was treated with flame-retardant coatings composed of poly (sodium phosphate), PSP, which acts as the acid source, and poly (allylamine), PAAm, which is used as the blowing agent, prepared via layer-by-layer (LbL) assembly. By applying these thin coating on fabric, after-glow is elimi...

  18. Iosipescu shear properties of graphite fabric/epoxy composite laminates

    NASA Technical Reports Server (NTRS)

    Walrath, D. E.; Adams, D. F.

    1985-01-01

    The Iosipescu shear test method is used to measure the in-plane and interlaminar shear properties of four T300 graphite fabric/934 epoxy composite materials. Different weave geometries tested include an Oxford weave, a 5-harness satin weave, an 8-harness satin weave, and a plain weave with auxiliary warp yarns. Both orthogonal and quasi-isotropic layup laminates were tested. In-plane and interlaminar shear properties are obtained for laminates of all four fabric types. Overall, little difference in shear properties attributable to the fabric weave pattern is observed. The auxiliary warp material is significantly weaker and less stiff in interlaminar shear parallel to its fill direction. A conventional strain gage extensometer is modified to measure shear strains for use with the Iosipescu shear test. While preliminary results are encouraging, several design iterations failed to produce a reliable shear transducer prototype. Strain gages are still the most reliable shear strain transducers for use with this test method.

  19. Axisymmetric transient thermal stress analysis of a multilayered composite hollow cylinder

    SciTech Connect

    Ootao, Y.; Tanigawa, Y.; Fukuda, T. Osaka Prefecture, University, Sakai Hitachi, Ltd., Yokohama )

    1991-06-01

    This article is concerned with axisymmetric, transient, thermal stress analysis of a hollow cylinder composed of multilayered composite laminates with temperature changes in the radial and axial directions due to axisymmetric heating from the outer and/or inner surfaces. The methods of Fourier cosine transform and Laplace transform are applied to the temperature field and the thermoelastic potential function, and Love's displacement function is applied to the thermoelastic field. Exact solutions are obtained for the temperature and thermal stress distributions in a transient state. Moreover, the theoretical developments proposed in the present article are applied to the analysis of a hollow cylinder with nonhomogeneous material properties, such as a functionally gradient material.

  20. Fabrication of robust multilayer films by triggering the coupling reaction between phenol and primary amine groups with visible light irradiation.

    PubMed

    Yu, You; Zhang, Hui; Cui, Shuxun

    2011-09-01

    We prepared robust cross-linked (x-linked) multilayer films under visible light irradiation with the catalysis of a Ru(ii) complex. The x-linking is achieved by the coupling reaction between phenol group and primary amine group within the self-assembled multilayer films that were prepared beforehand. Three kinds of polymers, i.e., poly(4-vinylphenol), poly(allylamine) and poly(ethyleneimine), were selected as the model system to illustrate the concept of this strategy. Upon visible light irradiation, the chemical stability of the x-linked films towards solution etching was greatly enhanced. In previous studies, horseradish peroxidase (HRP) is often utilized to catalyze the C-C, C-O and C-N coupling structures, which is useful to prepare polymers, capsules and bulk hydrogels. We also tried to prepare the x-linked films by the catalysis of HRP. The comparison of the two methods suggests that the Ru(ii) complex method is more ideal for fabricating x-linked films. In addition, the photo-triggered chemical reaction within the films was confirmed by the solid-state (13)C NMR, XPS and FT-IR measurements. Without UV light irradiation or thermal treatment, this strategy brings many advantages. It is anticipated that this approach can be easily extended to the applications of the biological related fields in the future. PMID:21837325

  1. Fabrication and temperature-dependent magnetic properties of one-dimensional multilayer Au–Ni–Au–Ni–Au nanowires

    SciTech Connect

    Ishrat, S.; Maaz, K.; Lee, Kyu-Joon; Jung, Myung-Hwa; Kim, Gil-Ho

    2014-02-15

    Multilayer Au–Ni–Au–Ni–Au nanowires with a controlled diameter of ∼100 nm were synthesized by electrochemical deposition in porous alumina templates. The length of each Ni-segment was controlled up to ∼230 nm, while the length of the Au segment sandwiched between two Ni segments was ∼180 nm. X-ray diffraction patterns and energy-dispersive X-ray spectra confirmed the formation of purely crystalline nanowires. The magnetic properties of the multilayer Au–Ni–Au–Ni–Au nanowires were investigated in the temperature range 2–300 K. Room-temperature magnetic hysteresis confirmed the ferromagnetic nature of the nanowires. The plot of coercivity as a function of temperature (from 2 to 300 K) followed law applicable for ferromagnetic nanostructures. The magnetization tended to increase as the temperature decreased, following the modified Bloch's law similar to ferromagnetic nanoparticles. - Graphical abstract: (a) SEM image of Au–Ni–Au–Ni–Au nanowire with 230 nm Ni segment length and 180 nm Au sandwiched between Ni segments (b) Kneller's law (c) Bloch's law Display Omitted - Highlights: • Electrochemical fabrication of Au–Ni–Au–Ni–Au nanowires in alumina templates. • Formation of beadlike structure of Ni segments. • Coercivity versus T follows Kneller's law for ferromagnetic materials. • Magnetization as a function of temperature follows the modified Bloch's law.

  2. Supercapacitors based on carbon nanotube fuzzy fabric structural composites

    NASA Astrophysics Data System (ADS)

    Alresheedi, Bakheet Awad

    Supercapacitors used in conjunction with batteries offer a solution to energy storage and delivery problems in systems where high power output is required, such as in fully electric cars. This project aimed to enhance current supercapacitor technology by fabricating activated carbon on a substrate consisting of carbon nanotubes (CNTs) grown on a carbon fiber fabric (fuzzy fabric). The fuzzy surface of CNTs lowers electrical resistance and increases porosity, resulting in a flexible fabric with high specific capacitance. Experimental results confirm that the capacitance of activated carbon fabricated on the fuzzy fiber composite is significantly higher than when activated carbon is formed simply on a bare carbon fiber substrate, indicating the usefulness of CNTs in supercapacitor technology. The fabrication of the fuzzy fiber based carbon electrode was fairly complex. The processing steps included composite curing, stabilization, carbonization and activation. Ratios of the three basic ingredients for the supercapacitor (fiber, CNT and polymer matrix) were investigated through experimentation and Grey relational analysis. The aim of Grey relational analysis was to examine factors that affect the overall performance of the supercapacitor. It is based on finding relationships in both independent and interrelated data series (parameters). Using this approach, it was determined that the amount of CNTs on the fiber surface plays a major role in the capacitor properties. An increased amount of CNTs increases the surface area and electrical conductivity of the substrate, while also reducing the required time of activation. Technical advances in the field of Materials and Structures are usually focused on attaining superior performance while reducing weight and cost. To achieve such combinations, multi-functionality has become essential; namely, to reduce weight by imparting additional functions simultaneously to a single material. In this study, a structural composite with

  3. Sputter deposition of multilayer thermoelectric films: An approach to the fabrication of two-dimensional quantum wells

    NASA Astrophysics Data System (ADS)

    Farmer, Joseph C.; Barbee, Troy W.; Chapline, George C.; Foreman, Ronald J.; Summers, Leslie J.; Dresselhaus, Mildred S.; Hicks, Lyndon D.

    1994-08-01

    The relative efficiency of a thermoelectric material is measured in terms of a dimensionless figure of merit, ZT. Though all known thermoelectric materials are believed to have ZT≤1, recent theoretical results predict that thermoelectric devices fabricated as two-dimensional quantum wells (2D QWs) or one-dimensional (1D) quantum wires could have ZT≥3. Multilayers with the dimensions of 2D QWs have been synthesized by alternately sputtering Bi0.9Sb0.1 and PbTe0.8Se0.2 onto a moving single-crystal sapphire substrate from dual magnetrons. These materials have been used to test the thermoelectric quantum-well concept and gain insight into relevant transport mechanisms. If successful, this research could lead to thermoelectric devices that have efficiencies close to that of an ideal Carnot engine. Ultimately, such devices could be used to replace conventional heat engines and mechanical refrigeration systems.

  4. Nanosilica-Chitosan Composite Coating on Cotton Fabrics

    NASA Astrophysics Data System (ADS)

    Maharani, Dina Kartika; Kartini, Indriana; Aprilita, Nurul Hidayat

    2010-10-01

    Nanosilica-chitosan composite coating on cotton fabrics has been prepared by sol-gel method. The sol-gel procedure allows coating of material on nanometer scale, which several commonly used coating procedure cannot achieve. In addition, sol-gel coating technique can be applied to system without disruption of their structure functionaly. The coating were produced via hidrolysis and condensation of TEOS and GPTMS and then mixed with chitosan. The composite coating on cotton fabrics were characterized with X-Ray Diffraction and Scanning Electron microscopy (SEM) method. The result showed that the coating not changed or disrupted the cotton stucture. The coating result in a clear transparent thin layer on cotton surface. The nanocomposite coating has new applications in daily used materials, especially those with low heat resistance, such as textiles and plastics, and as an environmentally friendly water-repellent substitute for fluorine compounds.

  5. Ultrasonic waves for fabricating lattice structure in composite materials

    NASA Astrophysics Data System (ADS)

    Saito, Mitsunori; Itagaki, Kazuhiro; Imanishi, Yoshihiro

    1999-09-01

    Ultrasonic waves are useful for arranging small particles in liquid, since the acoustic pressure exerts a sufficient trapping force on the particles. A composite material with layered structure can be fabricated by solidifying a particle suspension during the process of ultrasonic standing wave excitation. Fabrication of a 2D or 3D lattice structure is also possible by simultaneous excitation of two or three orthogonal ultrasonic standing waves. A polysiloxane resin is appropriate as a host material of such composite materials, since it is easily synthesized from a solution and its yields a small-periodicity structure due to its low sound velocity. Acrylic spheres, glass rods, and metal particles have been successfully arranged in polysiloxane resin forming layers or lattice structures. The spacing of particles was approximately 60 micrometers , which was half of the ultrasonic wavelength used. For heavy particles, a sample cell was continually rotated during the solidification process in order to prevent sedimentation.

  6. Slurry-based fabrication of chopped fiberglass composite preforms

    SciTech Connect

    Moore, G.A.; Johnson, R.W.; Landon, M.D.; Stoots, C.M.; Anderson, J.L.

    1995-12-01

    A water-based process for the fabrication of chopped fiberglass preforms is being developed in collaboration with the Automotive Composite Consortium (ACC) and The Budd Company. This slurry process uses hydraulic pressure to form highly compacted fiberglass preforms on contoured, perforated metal screens. The preforms will be used in the development of structural automotive composites. A key objective is to produce preforms having uniform areal density. Computational simulation of variable open area screens, and areal density mapping using a gamma densitometer are discussed.

  7. Analysis of woven fabrics for reinforced composite materials

    NASA Technical Reports Server (NTRS)

    Dow, Norris F.; Ramnath, V.; Rosen, B. Walter

    1987-01-01

    The use of woven fabrics as reinforcements for composites is considered. Methods of analysis of properties are reviewed and extended, with particular attention paid to three-dimensional constructions having through-the-thickness reinforcements. Methodology developed is used parametrically to evaluate the performance potential of a wide variety of reinforcement constructions including hybrids. Comparisons are made of predicted and measured properties of representative composites having biaxial and triaxial woven, and laminated tape lay-up reinforcements. Overall results are incorporated in advanced weave designs.

  8. Fabrication and Selective Functionalization of Amine-Reactive Polymer Multilayers on Topographically Patterned Microwell Cell Culture Arrays

    PubMed Central

    Broderick, Adam H.; Azarin, Samira M.; Buck, Maren E.; Palecek, Sean P.

    2011-01-01

    We report an approach to the fabrication and selective functionalization of amine-reactive polymer multilayers on the surfaces of three-dimensional (3-D) polyurethane-based microwell cell culture arrays. ‘Reactive’ layer-by-layer assembly of multilayers using branched polyethyleneimine (BPEI) and the azlactone-functionalized polymer poly(2-vinyl-4,4’-dimethylazlactone) (PVDMA) yielded film-coated microwell arrays that could be chemically functionalized post-fabrication by treatment with different amine-functionalized macromolecules or small molecule primary amines. Treatment of film-coated arrays with the small molecule amine D-glucamine resulted in microwell surfaces that resisted the adhesion and proliferation of mammalian fibroblast cells in vitro. These and other experiments demonstrated that it was possible to functionalize different structural features of these arrays in a spatially resolved manner to create dual-functionalized substrates (e.g., to create arrays having either (i) azlactone-functionalized wells, with regions between the wells functionalized with glucamine, or (ii) substrates with spatially resolved regions of two different cationic polymers). In particular, spatial control over glucamine functionalization yielded 3-D substrates that could be used to confine cell attachment and growth to microwells for periods of up to 28 days and support the 3-D culture of arrays of cuboidal cell clusters. These approaches to dual functionalization could prove useful for the long-term culture and maintenance of cell types for which the presentation of specific and chemically well-defined 3-D culture environments is required for control over cell growth, differentiation, and other important behaviors. More generally, our approach provides methods for the straightforward chemical functionalization of otherwise unreactive topographically patterned substrates that could prove useful in a range of other fundamental and applied contexts. PMID:21504222

  9. Fabrication of Fiber-Reinforced Celsian Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Setlock, John A.

    2000-01-01

    A method has been developed for the fabrication of small diameter, multifilament tow fiber reinforced ceramic matrix composites. Its application has been successfully demonstrated for the Hi-Nicalon/celsian system. Strong and tough celsian matrix composites, reinforced with BN/SiC-coated Hi-Nicalon fibers, have been fabricated by infiltrating the fiber tows with the matrix slurry, winding the tows on a drum, cutting and stacking of the prepreg tapes in the desired orientation, and hot pressing. The monoclinic celsian phase in the matrix was produced in situ, during hot pressing, from the 0.75BaO-0.25SrO-Al2O3-2SiO2 mixed precursor synthesized by solid state reaction from metal oxides. Hot pressing resulted in almost fully dense fiber-reinforced composites. The unidirectional composites having approx. 42 vol% of fibers exhibited graceful failure with extensive fiber pullout in three-point bend tests at room temperature. Values of yield stress and strain were 435 +/- 35 MPa and 0.27 +/- 0.01 percent, respectively, and ultimate strengths of 900 +/- 60 MPa were observed. The Young's modulus of the composites was measured to be 165 +/- 5 GPa.

  10. Evaluation of Double-Vacuum-Bag Process For Composite Fabrication

    NASA Technical Reports Server (NTRS)

    Hou, T. H.; Jensen, B. J.

    2004-01-01

    A non-autoclave vacuum bag process using atmospheric pressure alone that eliminates the need for external pressure normally supplied by an autoclave or a press is an attractive method for composite fabrication. This type of process does not require large capital expenditures for tooling and processing equipment. In the molding cycle (temperature/pressure profile) for a given composite system, the vacuum application point has to be carefully selected to achieve the final consolidated laminate net shape and resin content without excessive resin squeeze-out. The traditional single-vacuum- bag (SVB) process is best suited for molding epoxy matrix based composites because of their superior flow and the absence of reaction by-products or other volatiles. Other classes of materials, such as polyimides and phenolics, generate water during cure. In addition, these materials are commonly synthesized as oligomers using solvents to facilitate processability. Volatiles (solvents and reaction byproducts) management therefore becomes a critical issue. SVB molding, without additional pressure, normally fails to yield void-free quality composites for these classes of resin systems. A double-vacuum- bag (DVB) process for volatile management was envisioned, designed and built at the NASA Langley Research Center. This experimental DVB process affords superior volatiles management compared to the traditional SVB process. Void-free composites are consistently fabricated as measured by C-scan and optical photomicroscopy for high performance polyimide and phenolic resins.