Low temperature selective absorber research

NASA Astrophysics Data System (ADS)

Herzenberg, S. A.; Silberglitt, R.

1982-04-01

Research carried out since 1979 on selective absorbers is surveyed, with particular attention given to the low-temperature coatings seen as promising for flat plate and evacuated tube applications. The most thoroughly investigated absorber is black chrome, which is highly selective and is the most durable low-temperature absorber. It is believed that other materials, because of their low cost and lower content of strategic materials, may eventually supplant black chrome. Among these candidates are chemically converted black nickel; anodically oxidized nickel, zinc, and copper composites; and nickel or other low-cost multilayer coatings. In reviewing medium and high-temperature research, black chrome, multilayer coatings and black cobalt are seen as best medium-temperature candidates. For high temperatures, an Al2O3/Pt-Al203 multilayer composite or the zirconium diboride coating is preferred.

Predictive Models for Dynamic Brittle Fracture and Damage at High-velocity Impact in Multilayered Targets

DTIC Science & Technology

2016-11-01

layered glass/PC systems,Functionally Graded Materials (FGMs), polycrystalline AlON, and fiber-reinforced composite (FRC) materials. For the first time we...multi-layered glass/PC systems,Functionally Graded Materials (FGMs), polycrystalline AlON, and fiber-reinforced composite (FRC) materials. For the... Composite Lamina with Peridynamics, International Journal for Multiscale Computational Engineering, (12 2011): 0. doi: Florin Bobaru, Youn Doh Ha

Confine Clay in an Alternating Multilayered Structure through Injection Molding: A Simple and Efficient Route to Improve Barrier Performance of Polymeric Materials.

PubMed

Yu, Feilong; Deng, Hua; Bai, Hongwei; Zhang, Qin; Wang, Ke; Chen, Feng; Fu, Qiang

2015-05-20

Various methods have been devoted to trigger the formation of multilayered structure for wide range of applications. These methods are often complicated with low production efficiency or require complex equipment. Herein, we demonstrate a simple and efficient method for the fabrication of polymeric sheets containing multilayered structure with enhanced barrier property through high speed thin-wall injection molding (HSIM). To achieve this, montmorillonite (MMT) is added into PE first, then blended with PP to fabricate PE-MMT/PP ternary composites. It is demonstrated that alternating multilayer structure could be obtained in the ternary composites because of low interfacial tension and good viscosity match between different polymer components. MMT is selectively dispersed in PE phase with partial exfoliated/partial intercalated microstructure. 2D-WAXD analysis indicates that the clay tactoids in PE-MMT/PP exhibits an uniplanar-axial orientation with their surface parallel to the molded part surface, while the tactoids in binary PE-MMT composites with the same overall MMT contents illustrate less orientation. The enhanced orientation of nanoclay in PE-MMT/PP could be attributed to the confinement of alternating multilayer structure, which prohibits the tumbling and rotation of nanoplatelets. Therefore, the oxygen barrier property of PE-MMT/PP is superior to that of PE-MMT because of increased gas permeation pathway. Comparing with the results obtained for PE based composites in literature, outstanding barrier property performance (45.7% and 58.2% improvement with 1.5 and 2.5 wt % MMT content, respectively) is achieved in current study. Two issues are considered responsible for such improvement: enhanced MMT orientation caused by the confinement in layered structure, and higher local density of MMT in layered structure induced denser assembly. Finally, enhancement in barrier property by confining impermeable filler into alternating multilayer structure through such simple and efficient method could provide a novel route toward high-performance packaging materials and other functional materials require layered structure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Hongyi; Li, Yang; Zeng, Danielle

Process integration and optimization is the key enabler of the Integrated Computational Materials Engineering (ICME) of carbon fiber composites. In this paper, automated workflows are developed for two types of composites: Sheet Molding Compounds (SMC) short fiber composites, and multi-layer unidirectional (UD) composites. For SMC, the proposed workflow integrates material processing simulation, microstructure representation volume element (RVE) models, material property prediction and structure preformation simulation to enable multiscale, multidisciplinary analysis and design. Processing parameters, microstructure parameters and vehicle subframe geometry parameters are defined as the design variables; the stiffness and weight of the structure are defined as the responses. Formore » multi-layer UD structure, this work focuses on the discussion of different design representation methods and their impacts on the optimization performance. Challenges in ICME process integration and optimization are also summarized and highlighted. Two case studies are conducted to demonstrate the integrated process and its application in optimization.« less

Two-component end mills with multilayer composite nano-structured coatings as a viable alternative to monolithic carbide end mills

NASA Astrophysics Data System (ADS)

Vereschaka, Alexey; Mokritskii, Boris; Mokritskaya, Elena; Sharipov, Oleg; Oganyan, Maksim

2018-03-01

The paper deals with the challenges of the application of two-component end mills, which represent a combination of a carbide cutting part and a shank made of cheaper structural material. The calculations of strains and deformations of composite mills were carried out in comparison with solid carbide mills, with the use of the finite element method. The study also involved the comparative analysis of accuracy parameters of machining with monolithic mills and two-component mills with various shank materials. As a result of the conducted cutting tests in milling aluminum alloy with monolithic and two-component end mills with specially developed multilayer composite nano-structured coatings, it has been found that the use of such coatings can reduce strains and, correspondingly, deformations, which can improve the accuracy of machining. Thus, the application of two-component end mills with multilayer composite nano-structured coatings can provide a reduction in the cost of machining while maintaining or even improving the tool life and machining accuracy parameters.

Process Integration and Optimization of ICME Carbon Fiber Composites for Vehicle Lightweighting: A Preliminary Development

DOE PAGES

Xu, Hongyi; Li, Yang; Zeng, Danielle

2017-01-02

Process integration and optimization is the key enabler of the Integrated Computational Materials Engineering (ICME) of carbon fiber composites. In this paper, automated workflows are developed for two types of composites: Sheet Molding Compounds (SMC) short fiber composites, and multi-layer unidirectional (UD) composites. For SMC, the proposed workflow integrates material processing simulation, microstructure representation volume element (RVE) models, material property prediction and structure preformation simulation to enable multiscale, multidisciplinary analysis and design. Processing parameters, microstructure parameters and vehicle subframe geometry parameters are defined as the design variables; the stiffness and weight of the structure are defined as the responses. Formore » multi-layer UD structure, this work focuses on the discussion of different design representation methods and their impacts on the optimization performance. Challenges in ICME process integration and optimization are also summarized and highlighted. Two case studies are conducted to demonstrate the integrated process and its application in optimization.« less

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.

Reactive multilayers fabricated by vapor deposition. A critical review

DOE PAGES

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

Nanomembrane structures having mixed crystalline orientations and compositions

DOEpatents

Lagally, Max G.; Scott, Shelley A.; Savage, Donald E.

2014-08-12

The present nanomembrane structures include a multilayer film comprising a single-crystalline layer of semiconductor material disposed between two other single-crystalline layers of semiconductor material. A plurality of holes extending through the nanomembrane are at least partially, and preferably entirely, filled with a filler material which is also a semiconductor, but which differs from the nanomembrane semiconductor materials in composition, crystal orientation, or both.

Tribological Properties of Aluminium Alloy Composites Reinforced with Multi-Layer Graphene—The Influence of Spark Plasma Texturing Process

PubMed Central

Kostecki, Marek; Woźniak, Jarosław; Cygan, Tomasz; Petrus, Mateusz; Olszyna, Andrzej

2017-01-01

Self-lubricating composites are designed to obtain materials that reduce energy consumption, improve heat dissipation between moving bodies, and eliminate the need for external lubricants. The use of a solid lubricant in bulk composite material always involves a significant reduction in its mechanical properties, which is usually not an optimal solution. The growing interest in multilayer graphene (MLG), characterised by interesting properties as a component of composites, encouraged the authors to use it as an alternative solid lubricant in aluminium matrix composites instead of graphite. Aluminium alloy 6061 matrix composite reinforced with 2–15 vol % of MLG were synthesised by the spark plasma sintering process (SPS) and its modification, spark plasma texturing (SPT), involving deformation of the pre-sintered body in a larger diameter matrix. It was found that the application of the SPT method improves the density and hardness of the composites, resulting in improved tribological properties, particularly in the higher load regime. PMID:28796172

Properties of Exchange Coupled All-garnet Magneto-Optic Thin Film Multilayer Structures

PubMed Central

Nur-E-Alam, Mohammad; Vasiliev, Mikhail; Kotov, Viacheslav A.; Balabanov, Dmitry; Akimov, Ilya; Alameh, Kamal

2015-01-01

The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed. PMID:28788043

Self-assembled metal nano-multilayered film prepared by co-sputtering method

NASA Astrophysics Data System (ADS)

Xie, Tianle; Fu, Licai; Qin, Wen; Zhu, Jiajun; Yang, Wulin; Li, Deyi; Zhou, Lingping

2018-03-01

Nano-multilayered film is usually prepared by the arrangement deposition of different materials. In this paper, a self-assembled nano-multilayered film was deposited by simultaneous sputtering of Cu and W. The Cu/W nano-multilayered film was accumulated by W-rich layer and Cu-rich layer. Smooth interfaces with consecutive composition variation and semi-coherent even coherent relationship were identified, indicating that a spinodal-like structure with a modulation wavelength of about 20 nm formed during co-deposition process. The participation of diffusion barrier element, such as W, is believed the essential to obtain the nano-multilayered structure besides the technological parameters.

Influence of the composite material thermal expansion on embedded highly birefringent polymer microstructured optical fibers

NASA Astrophysics Data System (ADS)

SzelÄ g, M.; Lesiak, P.; Kuczkowski, M.; Domański, A. W.; Woliński, T. R.

2013-05-01

Results of our research on embedded highly birefringent polymer microstructured fibers are presented. A composite material sample with fibers embedded between two layers of a multi-layer composite structure is fabricated and characterized. Temperature sensitivities of the polymer fibers are measured in a free space and compared with the fibers embedded in the composite material. It appeared that highly birefringent polymer microstructured fibers exhibit a strong increase in temperature sensitivity when embedded in the composite material, which is due to the stress-induced changes in birefringence created by thermally-induced strain.

Ultrasonic Resonance Spectroscopy of Composite Rims for Flywheel Rotors

NASA Technical Reports Server (NTRS)

Harmon, Laura M.; Baaklini, George Y.

2002-01-01

Flywheel energy storage devices comprising multilayered composite rotor systems are being studied extensively for utilization in the International Space Station. These composite material systems were investigated with a recently developed ultrasonic resonance spectroscopy technique. The ultrasonic system employs a continuous swept-sine waveform and performs a fast Fourier transform (FFT) on the frequency response spectrum. In addition, the system is capable of equalizing the amount of energy at each frequency. Equalization of the frequency spectrum, along with interpretation of the second FFT, aids in the evaluation of the fundamental frequency. The frequency responses from multilayered material samples, with and without known defects, were analyzed to assess the capabilities and limitations of this nondestructive evaluation technique for material characterization and defect detection. Amplitude and frequency changes were studied from ultrasonic responses of thick composite rings and a multiring composite rim. A composite ring varying in thickness was evaluated to investigate the full thickness resonance. The frequency response characteristics from naturally occurring voids in a composite ring were investigated. Ultrasonic responses were compared from regions with and without machined voids in a composite ring and a multiring composite rim. Finally, ultrasonic responses from the multiring composite rim were compared before and after proof spin testing to 63,000 rpm.

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.

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.

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.

Ultrasonic Resonance Spectroscopy of Composite Rings for Flywheel Rotors

NASA Technical Reports Server (NTRS)

Harmon, Laura M.; Baaklini, George Y.

2001-01-01

Flywheel energy storage devices comprising multilayered composite rotor systems are being studied extensively for utilization in the International Space Station. These composite material systems were investigated with a recently developed ultrasonic resonance spectroscopy technique. The system employs a swept frequency approach and performs a fast Fourier transform on the frequency spectrum of the response signal. In addition. the system allows for equalization of the frequency spectrum, providing all frequencies with equal amounts of energy to excite higher order resonant harmonics. Interpretation of the second fast Fourier transform, along with equalization of the frequency spectrum, offers greater assurance in acquiring and analyzing the fundamental frequency, or spectrum resonance spacing. The range of frequencies swept in a pitch-catch mode was varied up to 8 MHz, depending on the material and geometry of the component. Single and multilayered material samples, with and without known defects, were evaluated to determine how the constituents of a composite material system affect the resonant frequency. Amplitude and frequency changes in the spectrum and spectrum resonance spacing domains were examined from ultrasonic responses of a flat composite coupon, thin composite rings, and thick composite rings. Also, the ultrasonic spectroscopy responses from areas with an intentional delamination and a foreign material insert, similar to defects that may occur during manufacturing malfunctions, were compared with those from defect-free areas in thin composite rings. A thick composite ring with varying thickness was tested to investigate the full-thickness resonant frequency and any possible bulk interfacial bond issues. Finally, the effect on the frequency response of naturally occurring single and clustered voids in a composite ring was established.

Imaging Arrays With Improved Transmit Power Capability

PubMed Central

Zipparo, Michael J.; Bing, Kristin F.; Nightingale, Kathy R.

2010-01-01

Bonded multilayer ceramics and composites incorporating low-loss piezoceramics have been applied to arrays for ultrasound imaging to improve acoustic transmit power levels and to reduce internal heating. Commercially available hard PZT from multiple vendors has been characterized for microstructure, ability to be processed, and electroacoustic properties. Multilayers using the best materials demonstrate the tradeoffs compared with the softer PZT5-H typically used for imaging arrays. Three-layer PZT4 composites exhibit an effective dielectric constant that is three times that of single layer PZT5H, a 50% higher mechanical Q, a 30% lower acoustic impedance, and only a 10% lower coupling coefficient. Application of low-loss multilayers to linear phased and large curved arrays results in equivalent or better element performance. A 3-layer PZT4 composite array achieved the same transmit intensity at 40% lower transmit voltage and with a 35% lower face temperature increase than the PZT-5 control. Although B-mode images show similar quality, acoustic radiation force impulse (ARFI) images show increased displacement for a given drive voltage. An increased failure rate for the multilayers following extended operation indicates that further development of the bond process will be necessary. In conclusion, bonded multilayer ceramics and composites allow additional design freedom to optimize arrays and improve the overall performance for increased acoustic output while maintaining image quality. PMID:20875996

High-performance multilayer composite membranes with mussel-inspired polydopamine as a versatile molecular bridge for CO2 separation.

PubMed

Li, Panyuan; Wang, Zhi; Li, Wen; Liu, Yanni; Wang, Jixiao; Wang, Shichang

2015-07-22

It is desirable to develop high-performance composite membranes for efficient CO2 separation in CO2 capture process. Introduction of a highly permeable polydimethylsiloxane (PDMS) intermediate layer between a selective layer and a porous support has been considered as a simple but efficient way to enhance gas permeance while maintaining high gas selectivity, because the introduced intermediate layer could benefit the formation of an ultrathin defect-free selective layer owing to the circumvention of pore penetration phenomenon. However, the selection of selective layer materials is unfavorably restricted because of the low surface energy of PDMS. Various highly hydrophilic membrane materials such as amino group-rich polyvinylamine (PVAm), a representative facilitated transport membrane material for CO2 separation, could not be facilely coated over the surface of the hydrophobic PDMS intermediate layer uniformly. Inspired by the hydrophilic nature and strong adhesive ability of polydopamine (PDA), PDA was therefore selected as a versatile molecular bridge between hydrophobic PDMS and hydrophilic PVAm. The PDA coating endows a highly compatible interface between both components with a large surface energy difference via multiple-site cooperative interactions. The resulting multilayer composite membrane with a thin facilitated transport PVAm selective layer exhibits a notably enhanced CO2 permeance (1887 GPU) combined with a slightly improved CO2/N2 selectivity (83), as well as superior structural stability. Similarly, the multilayer composite membrane with a hydrophilic CO2-philic Pebax 1657 selective layer was also developed for enhanced CO2 separation performance.

Asynchronous cracking with dissimilar paths in multilayer graphene.

PubMed

Jang, Bongkyun; Kim, Byungwoon; Kim, Jae-Hyun; Lee, Hak-Joo; Sumigawa, Takashi; Kitamura, Takayuki

2017-11-16

Multilayer graphene consists of a stack of single-atomic-thick monolayer graphene sheets bound with π-π interactions and is a fascinating model material opening up a new field of fracture mechanics. In this study, fracture behavior of single-crystalline multilayer graphene was investigated using an in situ mode I fracture test under a scanning electron microscope, and abnormal crack propagation in multilayer graphene was identified for the first time. The fracture toughness of graphene was determined from the measured load-displacement curves and the realistic finite element modelling of specimen geometries. Nonlinear fracture behavior of the multilayer graphene is discussed based on nonlinear elastic fracture mechanics. In situ scanning electron microscope images obtained during the fracture test showed asynchronous crack propagation along independent paths, causing interlayer shear stress and slippages. We also found that energy dissipation by interlayer slippages between the graphene layers is the reason for the enhanced fracture toughness of multilayer graphene. The asynchronous cracking with independent paths is a unique cracking and toughening mechanism for single-crystalline multilayer graphene, which is not observed for the monolayer graphene. This could provide a useful insight for the design and development of graphene-based composite materials for structural applications.

Multilayer ultra-high-temperature ceramic coatings

DOEpatents

Loehman, Ronald E [Albuquerque, NM; Corral, Erica L [Tucson, AZ

2012-03-20

A coated carbon-carbon composite material with multiple ceramic layers to provide oxidation protection from ultra-high-temperatures, where if the carbon-carbon composite material is uninhibited with B.sub.4C particles, then the first layer on the composite material is selected from ZrB.sub.2 and HfB.sub.2, onto which is coated a layer of SiC coated and if the carbon-carbon composite material is inhibited with B.sub.4C particles, then protection can be achieved with a layer of SiC and a layer of either ZrB.sub.2 and HfB.sub.2 in any order.

Investigation into Composites Property Effect on the Forming Limits of Multi-Layer Hybrid Sheets Using Hydroforming Technology

NASA Astrophysics Data System (ADS)

Liu, Shichen; Lang, Lihui; Guan, Shiwei; Alexandrov, Seigei; Zeng, Yipan

2018-04-01

Fiber-metal laminates (FMLs) such as Kevlar reinforced aluminum laminate (ARALL), Carbon reinforced aluminum laminate (CARALL), and Glass reinforced aluminum laminate (GLARE) offer great potential for weight reduction applications in automobile and aerospace construction. In order to investigate the feasibility for utilizing such materials in the form of laminates, sheet hydroforming technology are studied under the condition of uniform blank holder force for three-layered aluminum and aluminum-composite laminates using orthogonal carbon and Kevlar as well as glass fiber in the middle. The experimental results validate the finite element results and they exhibited that the forming limit of glass fiber in the middle is the highest among the studied materials, while carbon fiber material performs the worst. Furthermore, the crack modes are different for the three kinds of fiber materials investigated in the research. This study provides fundamental guidance for the selection of multi-layer sheet materials in the future manufacturing field.

Flaw detection in a multi-material multi-layered composite: using fem and air-coupled ut

DOE Office of Scientific and Technical Information (OSTI.GOV)

Livings, R. A.; Dayal, V.; Barnard, D. J.

Ceramic tiles are the main ingredient of a multi-layer multi-material composite being considered for the modernization of tank armors. The high stiffness, low attenuation, and precise dimensions of these uniform tiles make them remarkable resonators when driven to vibrate. This study is aimed at modeling the vibration modes of the tiles and the composite lay-up with finite element analysis and comparing the results with the resonance modes observed in air-coupled ultrasonic excitation of the tiles and armor samples. Defects in the tile, during manufacturing and/or after usage, are expected to change the resonance modes. The comparison of a pristine tile/lay-upmore » and a defective tile/lay-up will thus be a quantitative damage metric. The understanding of the vibration behavior of the tile, both by itself and in the composite lay-up, can provide useful guidance to the nondestructive evaluation of armor panels containing ceramic tiles.« less

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.

Multi-layer composite mechanical modeling for the inhomogeneous biofilm mechanical behavior.

PubMed

Wang, Xiaoling; Han, Jingshi; Li, Kui; Wang, Guoqing; Hao, Mudong

2016-08-01

Experiments showed that bacterial biofilms are heterogeneous, for example, the density, the diffusion coefficient, and mechanical properties of the biofilm are different along the biofilm thickness. In this paper, we establish a multi-layer composite model to describe the biofilm mechanical inhomogeneity based on unified multiple-component cellular automaton (UMCCA) model. By using our model, we develop finite element simulation procedure for biofilm tension experiment. The failure limit and biofilm extension displacement obtained from our model agree well with experimental measurements. This method provides an alternative theory to study the mechanical inhomogeneity in biological materials.

Changes of composition and microstructure of joint interface of tungsten coated carbon by high heat flux

NASA Astrophysics Data System (ADS)

Tokunaga, K.; Matsubara, T.; Miyamoto, Y.; Takao, Y.; Yoshida, N.; Noda, N.; Kubota, Y.; Sogabe, T.; Kato, T.; Plöchl, L.

2000-12-01

Tungsten coatings of 0.5 and 1 mm thickness were successfully deposited by the vacuum plasma spraying (VPS) technique on carbon/carbon fiber composite (CFC), CX-2002U and isotropic fine grained graphite, IG-430U. High heat flux experiments by irradiation of electron beam with uniform profile were performed on the coated samples in order to prove the suitability and load limit of such coating materials. The cross-sectional composition and structure of the interface of VPS-W and carbon material samples were investigated. Compositional analyses showed that the Re/W multi-layer acts as diffusion barrier for carbon and suppresses tungsten carbide formation in the VPS-W layer at high temperature about 1300°C. Microstructure of the joint interface of the sample changed in the case of a peak temperature of about 2800°C. The multi-layer structure completely disappeared and compositional distribution was almost uniform in the interface of the sample after melting and resolidification. The diffusion barrier for carbon is not expected to act in this stage.

Metallic multilayers at the nanoscale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jankowski, A.F.

1994-11-01

The development of multilayer structures has been driven by a wide range of commercial applications requiring enhanced material behaviors. Innovations in physical vapor deposition technologies, in particular magnetron sputtering, have enabled the synthesis of metallic-based structures with nanoscaled layer dimensions as small as one-to-two monolayers. Parameters used in the deposition process are paramount to the Formation of these small layer dimensions and the stability of the structure. Therefore, optimization of the desired material properties must be related to assessment of the actual microstructure. Characterization techniques as x-ray diffraction and high resolution microscopy are useful to reveal the interface and layermore » structure-whether ordered or disordered crystalline, amorphous, compositionally abrupt or graded, and/or lattice strained Techniques for the synthesis of metallic multilayers with subnanometric layers will be reviewed with applications based on enhancing material behaviors as reflectivity and magnetic anisotropy but with emphasis on experimental studies of mechanical properties.« less

Proving the viability of manufacturing of multi-layer steel/vanadium alloy/steel composite tubes by numerical simulations and experiment

NASA Astrophysics Data System (ADS)

Nechaykina, T.; Nikulin, S.; Rozhnov, A.; Molotnikov, A.; Zavodchikov, S.; Estrin, Y.

2018-05-01

Vanadium alloys are promising structural materials for fuel cladding tubes for fast-neutron reactors. However, high solubility of oxygen and nitrogen in vanadium alloys at operating temperatures of 700 °C limits their application. In this work, we present a novel composite structure consisting of vanadium alloy V-4Ti-4Cr (provides high long-term strength of the material) and stainless steel Fe-0.2C-13Cr (as a corrosion resistant protective layer). It is produced by co-extrusion of these materials forming a three-layered tube. Finite element simulations were utilised to explore the influence of the various co-extrusion parameters on manufacturability of multi-layered tubes. Experimental verification of the numerical modelling was performed using co-extrusion with the process parameters suggested by the numerical simulations. Scanning electron microscopy and microhardness measurements revealed a defect-free diffusion layer at the interfaces between both materials indicating a good quality bonding for these co-extrusion conditions.

Prediction and characterization of heat-affected zone formation in tin-bismuth alloys due to nickel-aluminum multilayer foil reaction

DOE PAGES

Hooper, R. J.; Davis, C. G.; Johns, P. M.; ...

2015-06-26

Reactive multilayer foils have the potential to be used as local high intensity heat sources for a variety of applications. In this study, most of the past research effort concerning these materials have focused on understanding the structure-property relationships of the foils that govern the energy released during a reaction. To improve the ability of researchers to more rapidly develop technologies based on reactive multilayer foils, a deeper and more predictive understanding of the relationship between the heat released from the foil and microstructural evolution in the neighboring materials is needed. This work describes the development of a numerical modelmore » for the purpose of predicting heat affected zone size in substrate materials. The model is experimentally validated using a commercially available Ni-Al multilayer foils and alloys from the Sn-Bi binary system. To accomplish this, phenomenological models for predicting the variation of physical properties (i.e., thermal conductivity, density, and heat capacity) with temperature and composition in the Sn-Bi system were utilized using literature data.« less

Multilayer Electroactive Polymer Composite Material

NASA Technical Reports Server (NTRS)

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

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.

Effect of Ply Orientation and Crack Location on SIFs in Finite Multilayers with Aligned Cracks

NASA Astrophysics Data System (ADS)

Chen, Linfeng; Pindera, Marek-Jerzy

2008-02-01

An exact elasticity solution is presented for arbitrarily laminated finite multilayers in a state of generalized plane deformation under horizontally pinned end constraints that are weakened by aligned cracks. Based on half-range Fourier series and the local/global stiffness matrix approach, the mixed boundary-value problem is reduced to Cauchy-type singular integral equations in the unknown displacement discontinuities. Solution to these equations is obtained using the approach developed by Erdogan and co-workers. Numerical results quantify the thus-far undocumented geometric and material effects on Mode I, II and III stress intensity factors in composite multilayers with interacting cracks under uniform vertical displacement. These effects include finite dimensions, crack location, material anisotropy due to a unidirectional fiber-reinforced layer/s orientation, and orientational grading.

The design of a Li-ion full cell battery using a nano silicon and nano multi-layer graphene composite anode

NASA Astrophysics Data System (ADS)

Eom, KwangSup; Joshi, Tapesh; Bordes, Arnaud; Do, Inhwan; Fuller, Thomas F.

2014-03-01

In this study, a Si-graphene composite, which is composed of nano Si particles and nano-sized multi-layer graphene particles, and micro-sized multi-layer graphene plate conductor, was used as the anode for Li-ion battery. The Si-graphene electrode showed the high capacity and stable cyclability at charge/discharge rate of C/2 in half cell tests. Nickel cobalt aluminum material (NCA) was used as a cathode in the full cell to evaluate the practicality of the new Si-graphene material. Although the Si-graphene anode has more capacity than the NCA cathode in this designed full cell, the Si-graphene anode had a greater effect on the full-cell performance due to its large initial irreversible capacity loss and continuous SEI formation during cycling. When fluoro-ethylene carbonate was added to the electrolyte, the cyclability of the full cell was much improved due to less SEI formation, which was confirmed by the decreases in the 1st irreversible capacity loss, overpotential for the 1st lithiation, and the resistance of the SEI.

Thermal Insulation System for Non-Vacuum Applications Including a Multilayer Composite

NASA Technical Reports Server (NTRS)

Fesmire, James E. (Inventor)

2017-01-01

The thermal insulation system of the present invention is for non-vacuum applications and is specifically tailored to the ambient pressure environment with any level of humidity or moisture. The thermal insulation system includes a multilayered composite including i) at least one thermal insulation layer and at least one compressible barrier layer provided as alternating, successive layers, and ii) at least one reflective film provided on at least one surface of the thermal insulation layer and/or said compressible barrier layer. The different layers and materials and their combinations are designed to provide low effective thermal conductivity for the system by managing all modes of heat transfer. The thermal insulation system includes an optional outer casing surrounding the multilayered composite. The thermal insulation system is particularly suited for use in any sub-ambient temperature environment where moisture or its adverse effects are a concern. The thermal insulation system provides physical resilience against damaging mechanical effects including compression, flexure, impact, vibration, and thermal expansion/contraction.

Hybrid use of combined and sequential delivery of growth factors and ultrasound stimulation in porous multilayer composite scaffolds to promote both vascularization and bone formation in bone tissue engineering.

PubMed

Yan, Haoran; Liu, Xia; Zhu, Minghua; Luo, Guilin; Sun, Tao; Peng, Qiang; Zeng, Yi; Chen, Taijun; Wang, Yingying; Liu, Keliang; Feng, Bo; Weng, Jie; Wang, Jianxin

2016-01-01

In this study, a multilayer coating technology would be adopted to prepare a porous composite scaffold and the growth factor release and ultrasound techniques were introduced into bone tissue engineering to finally solve the problems of vascularization and bone formation in the scaffold whilst the designed multilayer composite with gradient degradation characteristics in the space was used to match the new bone growth process better. The results of animal experiments showed that the use of low intensity pulsed ultrasound (LIPUS) combined with growth factors demonstrated excellent capabilities and advantages in both vascularization and new bone formation in bone tissue engineering. The degradation of the used scaffold materials could match new bone formation very well. The results also showed that only RGD-promoted cell adhesion was insufficient to satisfy the needs of new bone formation while growth factors and LIPUS stimulation were the key factors in new bone formation. © 2015 Wiley Periodicals, Inc.

Active thermography in qualitative evaluation of protective materials.

PubMed

Gralewicz, Grzegorz; Wiecek, Bogusław

2009-01-01

This is a study of the possibilities of a qualitative evaluation of protective materials with active thermography. It presents a simulation of a periodic excitation of a multilayer composite material. Tests were conducted with lock-in thermography on Kevlar composite consisting of 16 layers of Kevlar fabric reinforced with formaldehyde resin with implanted delamination defects. Lock-in thermography is a versatile tool for nondestructive evaluation. It is a fast, remote and nondestructive procedure. Hence, it was used to detect delaminations in the composite structure of materials used in the production of components designed for personal protection. This method directly contributes to an improvement in safety.

Finite Element Modeling of Multilayer Orthogonal Auxetic Composites under Low-Velocity Impact

PubMed Central

Jiang, Lili; Hu, Hong

2017-01-01

The multilayer orthogonal auxetic composites have been previously developed and tested to prove that they own excellent energy absorption and impact protection characteristics in a specific strain range under low-velocity impact. In this study, a three dimensional finite element (FE) model in ANSYS LS-DYNA was established to simulate the mechanical behavior of auxetic composites under low-velocity drop-weight impact. The simulation results including the Poisson’s ratio versus compressive strain curves and the contact stress versus compressive strain curves were compared with those in the experiments. The clear deformation pictures of the FE models have provided a simple and effective way for investigating the damage mechanism and optimizing the material, as well as structure design. PMID:28783054

Room- and Low-Temperature Deformation of Multilayered Fiberglass Plastics Reinforced with a Fabric of Sateen Weave

NASA Astrophysics Data System (ADS)

Kucher, N. K.; Dveyrin, A. Z.; Zarazovskii, M. N.; Zemtsov, M. P.

2004-05-01

The regularities of elastic deformation of multilayered fiberglass plastics reinforced with a fabric of sateen weave are studied. The effect of cooling to 77 K on the averaged elastic characteristics of the orthotropic material is analyzed. The efficiency of mathematical modeling in calculating the stiffness and compliance parameters of the woven composites based on the geometry and mechanical properties of their constituents is investigated.

Layer-by-Layer Motif Architectures: Programmed Electrochemical Syntheses of Multilayer Mesoporous Metallic Films with Uniformly Sized Pores.

PubMed

Jiang, Bo; Li, Cuiling; Qian, Huayu; Hossain, Md Shahriar A; Malgras, Victor; Yamauchi, Yusuke

2017-06-26

Although multilayer films have been extensively reported, most compositions have been limited to non-catalytically active materials (e.g. polymers, proteins, lipids, or nucleic acids). Herein, we report the preparation of binder-free multilayer metallic mesoporous films with sufficient accessibility for high electrocatalytic activity by using a programmed electrochemical strategy. By precisely tuning the deposition potential and duration, multilayer mesoporous architectures consisting of alternating mesoporous Pd layers and mesoporous PdPt layers with controlled layer thicknesses can be synthesized within a single electrolyte, containing polymeric micelles as soft templates. This novel architecture, combining the advantages of bimetallic alloys, multilayer architectures, and mesoporous structures, exhibits high electrocatalytic activity for both the methanol oxidation reaction (MOR) and the ethanol oxidation reaction (EOR). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theoretical Design of Multilayer Dental Posts Using CAD-Based Approach and Sol-Gel Chemistry.

PubMed

Maietta, Saverio; De Santis, Roberto; Catauro, Michelina; Martorelli, Massimo; Gloria, Antonio

2018-05-07

A computer-aided design (CAD)-based approach and sol-gel chemistry were used to design a multilayer dental post with a compositional gradient and a Young’s modulus varying from 12.4 to 2.3 GPa in the coronal-apical direction. Specifically, we propose a theoretical multilayer post design, consisting of titanium dioxide (TiO₂) and TiO₂/poly(ε-caprolactone) (PCL) hybrid materials containing PCL up to 24% by weight obtained using the sol-gel method. The current study aimed to analyze the effect of the designed multilayer dental post in endodontically treated anterior teeth. Stress distribution was investigated along and between the post and the surrounding structures. In comparison to a metal post, the most uniform distributions with lower stress values and no significant stress concentration were found when using the multilayer post.

Thermogravimetric and microscopic analysis of SiC/SiC materials with advanced interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Windisch, C.F. Jr.; Jones, R.H.; Snead, L.L.

1997-04-01

The chemical stability of SiC/SiC composites with fiber/matrix interfaces consisting of multilayers of SiC/SiC and porous SiC have been evaluated using a thermal gravimetric analyzer (TGA). Previous evaluations of SiC/SiC composites with carbon interfacial layers demonstrated the layers are not chemically stable at goal use temperatures of 800-1100{degrees}C and O{sub 2} concentrations greater than about 1 ppm. No measureable mass change was observed for multilayer and porous SiC interfaces at 800-1100{degrees}C and O{sub 2} concentrations of 100 ppm to air; however, the total amount of oxidizable carbon is on the order of the sensitivity of the TGA. Further studies aremore » in progress to evaluate the stability of these materials.« less

Background-reducing X-ray multilayer mirror

DOEpatents

Bloch, Jeffrey J.; Roussel-Dupre', Diane; Smith, Barham W.

1992-01-01

Background-reducing x-ray multilayer mirror. A multiple-layer "wavetrap" deposited over the surface of a layered, synthetic-microstructure soft x-ray mirror optimized for reflectivity at chosen wavelengths is disclosed for reducing the reflectivity of undesired, longer wavelength incident radiation incident thereon. In three separate mirror designs employing an alternating molybdenum and silicon layered, mirrored structure overlaid by two layers of a molybdenum/silicon pair anti-reflection coating, reflectivities of near normal incidence 133, 171, and 186 .ANG. wavelengths have been optimized, while that at 304 .ANG. has been minimized. The optimization process involves the choice of materials, the composition of the layer/pairs as well as the number thereof, and the distance therebetween for the mirror, and the simultaneous choice of materials, the composition of the layer/pairs, and their number and distance for the "wavetrap."

Piezoelectric Actuator/Sensor Technology at Rockwell

NASA Technical Reports Server (NTRS)

Neurgaonkar, Ratnakar R.

1996-01-01

We describe the state-of-the art of piezoelectric materials based on perovskite and tungsten bronze families for sensor, actuator and smart structure applications. The microstructural defects in these materials have been eliminated to a large extent and the resulting materials exhibit exceedingly high performance for various applications. The performance of Rockwell actuators/sensors is at least 3 times better than commercially available products. These high performance actuators are being incorporated into various applications including, DOD, NASA and commercial. The multilayer actuator stacks fabricated from our piezoceramics are advantageous for sensing and high capacitance applications. In this presentation, we will describe the use of our high performance piezo-ceramics for actuators and sensors, including multilayer stacks and composite structures.

Cladding material, tube including such cladding material and methods of forming the same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garnier, John E.; Griffith, George W.

A multi-layered cladding material including a ceramic matrix composite and a metallic material, and a tube formed from the cladding material. The metallic material forms an inner liner of the tube and enables hermetic sealing of thereof. The metallic material at ends of the tube may be exposed and have an increased thickness enabling end cap welding. The metallic material may, optionally, be formed to infiltrate voids in the ceramic matrix composite, the ceramic matrix composite encapsulated by the metallic material. The ceramic matrix composite includes a fiber reinforcement and provides increased mechanical strength, stiffness, thermal shock resistance and highmore » temperature load capacity to the metallic material of the inner liner. The tube may be used as a containment vessel for nuclear fuel used in a nuclear power plant or other reactor. Methods for forming the tube comprising the ceramic matrix composite and the metallic material are also disclosed.« less

Modeling of layered anisotropic composite material based on effective medium theory

NASA Astrophysics Data System (ADS)

Bao, Yang; Song, Jiming

2018-04-01

In this paper, we present an efficient method to simulate multilayered anisotropic composite material with effective medium theory. Effective permittivity, permeability and orientation angle for a layered anisotropic composite medium are extracted with this equivalent model. We also derive analytical expressions for effective parameters and orientation angle with low frequency (LF) limit, which will be shown in detail. Numerical results are shown in comparing extracted effective parameters and orientation angle with analytical results from low frequency limit. Good agreements are achieved to demonstrate the accuracy of our efficient model.

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.

Two Dimensional (2D) P-Aramid Dry Multi-Layered Woven Fabrics Deformational Behaviour for Technical Applications

NASA Astrophysics Data System (ADS)

Abtew, M. A.; Loghin, C.; Cristian, I.; Boussu, F.; Bruniaux, P.; Chen, Y.; Wang, L.

2018-06-01

In today’s scenario for the various technical applications, from composites to body armour, the material mouldability along with its mechanical property become very important. In the present study, two dimensional (2D) woven fabrics made of para-aramid high performance fibres in multi-layer dry structure were used for investigating different forming characteristics. The different layers were arranged with 0°/90° orientation for deep drawing formability test to analyse the effect of number of layers and blank-holder pressure (BHP) during the test. Specific preforming device with low speed forming process and predefined hemispherical shape of punch has been applied. Using fine photographic analysis, some important 2D multi-layer fabrics forming characteristics i.e., material drawing-in, surface shear angle etc. from the imposed deformation have been observed, measured and analysed for better understanding and co MPa rison. The result revealed that the mouldability behaviour of the multi-layered dry textile fabric preforms is directional, and closely dependent on blank-holding pressure and number of layers. This indicates both parameters should be carefully considered while material deformation to avoid the formation of wrinkling and maintain other mechanical properties on final application.

Energy transfer through a multi-layer liner for shaped charges

DOEpatents

Skolnick, Saul; Goodman, Albert

1985-01-01

This invention relates to the determination of parameters for selecting materials for use as liners in shaped charges to transfer the greatest amount of energy to the explosive jet. Multi-layer liners constructed of metal in shaped charges for oil well perforators or other applications are selected in accordance with the invention to maximize the penetrating effect of the explosive jet by reference to four parameters: (1) Adjusting the explosive charge to liner mass ratio to achieve a balance between the amount of explosive used in a shaped charge and the areal density of the liner material; (2) Adjusting the ductility of each layer of a multi-layer liner to enhance the formation of a longer energy jet; (3) Buffering the intermediate layers of a multi-layer liner by varying the properties of each layer, e.g., composition, thickness, ductility, acoustic impedance and areal density, to protect the final inside layer of high density material from shattering upon impact of the explosive force and, instead, flow smoothly into a jet; and (4) Adjusting the impedance of the layers in a liner to enhance the transmission and reduce the reflection of explosive energy across the interface between layers.

Microwave absorption properties of carbon nanocoils coated with highly controlled magnetic materials by atomic layer deposition.

PubMed

Wang, Guizhen; Gao, Zhe; Tang, Shiwei; Chen, Chaoqiu; Duan, Feifei; Zhao, Shichao; Lin, Shiwei; Feng, Yuhong; Zhou, Lei; Qin, Yong

2012-12-21

In this work, atomic layer deposition is applied to coat carbon nanocoils with magnetic Fe(3)O(4) or Ni. The coatings have a uniform and highly controlled thickness. The coated nanocoils with coaxial multilayer nanostructures exhibit remarkably improved microwave absorption properties compared to the pristine carbon nanocoils. The enhanced absorption ability arises from the efficient complementarity between complex permittivity and permeability, chiral morphology, and multilayer structure of the products. This method can be extended to exploit other composite materials benefiting from its convenient control of the impedance matching and combination of dielectric-magnetic multiple loss mechanisms for microwave absorption applications.

Thin and Flexible Fe-Si-B/Ni-Cu-P Metallic Glass Multilayer Composites for Efficient Electromagnetic Interference Shielding.

PubMed

Zhang, Jijun; Li, Jiawei; Tan, Guoguo; Hu, Renchao; Wang, Junqiang; Chang, Chuntao; Wang, Xinmin

2017-12-06

Thin and flexible materials that can provide efficient electromagnetic interference (EMI) shielding are urgently needed, especially if they can be easily processed and withstand harsh environments. Herein, layer-structured Fe-Si-B/Ni-Cu-P metallic glass composites have been developed by simple electroless plating Ni-Cu-P coating on commercial Fe-Si-B metallic glasses. The 0.1 mm-thick composite shows EMI shielding effectiveness of 40 dB over the X-band frequency range, which is higher than those of traditional metals, metal oxides, and their polymer composites of larger thickness. Most of the applied electromagnetic waves are proved to be absorbed rather than bounced back. This performance originates from the combination of a superior soft magnetic property, excellent electrical conductivity, and multiple internal reflections from multilayer composites. In addition, the flexible composites also exhibit good corrosion resistance, high thermal stability, and excellent tensile strength, making them suitable for EMI shielding in harsh chemical or thermal environments.

Explicit Finite Element Method for Transparency Impact Analysis

DTIC Science & Technology

1991-06-01

investigators have employed a similar concept for fiber-reinforced composite laminates (Chow 1971, 1975; Noor 1975, 1989; Chatterjee, 1979). Consider...Intense Impulsive Loads, It. J. Nuon. Meth. Engng. 14, 1865- 1871. Jones, R. M. (1975), Mechanics of Composite Materials, Scripta Book Co., Washington, D...Structural Dynamics, J. Eng. Mech. Div. 85, 67-94. Noor, A. K. (1975), Stability of Multilayered Composite Plates, Fibre Sci. Tech. 8, 81-89. Noor, A. K

Microstructure and composition analysis of low-Z/low-Z multilayers by combining hard and resonant soft X-ray reflectivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, P. N., E-mail: pnrao@rrcat.gov.in; Rai, S. K.; Srivastava, A. K.

2016-06-28

Microstructure and composition analysis of periodic multilayer structure consisting of a low electron density contrast (EDC) material combination by grazing incidence hard X-ray reflectivity (GIXR), resonant soft X-ray reflectivity (RSXR), and transmission electron microscopy (TEM) are presented. Measurements of reflectivity at different energies allow combining the sensitivity of GIXR data to microstructural parameters like layer thicknesses and interfacing roughness, with the layer composition sensitivity of RSXR. These aspects are shown with an example of 10-period C/B{sub 4}C multilayer. TEM observation reveals that interfaces C on B{sub 4}C and B{sub 4}C on C are symmetric. Although GIXR provides limited structural informationmore » when EDC between layers is low, measurements using a scattering technique like GIXR with a microscopic technique like TEM improve the microstructural information of low EDC combination. The optical constants of buried layers have been derived by RSXR. The derived optical constants from the measured RSXR data suggested the presence of excess carbon into the boron carbide layer.« less

Energetic composite and system with enhanced mechanical sensitivity to initiation of self-sustained reaction

DOEpatents

Gash, Alexander E [Brentwood, CA; Barbee, Jr., Troy W.

2012-05-29

An energetic composition and system using amassed energetic multilayer pieces which are formed from the division, such as for example by cutting, scoring, breaking, crushing, shearing, etc., of a mechanically activatable monolithic energetic multilayer(s) (e.g. macro-scale sheets of multilayer films), for enhancing the sensitivity of the energetic composite and system to mechanical initiation of self-sustained reaction. In particular, mechanical initiation of the energetic composition may be achieved with significantly lower mechanical energy inputs than that typically required for initiating the monolithic energetic multilayers from which it is derived.

Attenuation of stress waves in single and multi-layered structures. [mitigation of elastic and plastic stress waves during spacecraft landing

NASA Technical Reports Server (NTRS)

Yang, J. C. S.; Tsui, C. Y.

1972-01-01

Analytical and experimental studies were made of the attenuation of the stress waves during passage through single and multilayer structures. The investigation included studies on elastic and plastic stress wave propagation in the composites and those on shock mitigating material characteristics such as dynamic stress-strain relations and energy absorbing properties. The results of the studies are applied to methods for reducing the stresses imposed on a spacecraft during planetary or ocean landings.

Reduction of thermal conductivity in MnSi{sub 1.7} multi-layered thin films with artificially inserted Si interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurosaki, Y., E-mail: yosuke.kurosaki.uy@hitachi.com; Yabuuchi, S.; Nishide, A.

We report a lowered lattice thermal conductivity in nm-scale MnSi{sub 1.7}/Si multilayers which were fabricated by controlling thermal diffusions of Mn and Si atoms. The thickness of the constituent layers is 1.5–5.0 nm, which is comparable to the phonon mean free path of both MnSi{sub 1.7} and Si. By applying the above nanostructures, we reduced the lattice thermal conductivity down to half that of bulk MnSi{sub 1.7}/Si composite materials. The obtained value of 1.0 W/K m is the experimentally observed minimum in MnSi{sub 1.7}-based materials without any heavy element doping and close to the minimum thermal conductivity. We attribute the reduced latticemore » thermal conductivity to phonon scattering at the MnSi{sub 1.7}/Si interfaces in the multilayers.« less

Supramolecular self-assembly of graphene oxide and metal nanoparticles into stacked multilayers by means of a multitasking protein ring.

PubMed

Ardini, Matteo; Golia, Giordana; Passaretti, Paolo; Cimini, Annamaria; Pitari, Giuseppina; Giansanti, Francesco; Di Leandro, Luana; Ottaviano, Luca; Perrozzi, Francesco; Santucci, Sandro; Morandi, Vittorio; Ortolani, Luca; Christian, Meganne; Treossi, Emanuele; Palermo, Vincenzo; Angelucci, Francesco; Ippoliti, Rodolfo

2016-03-28

Graphene oxide (GO) is rapidly emerging worldwide as a breakthrough precursor material for next-generation devices. However, this requires the transition of its two-dimensional layered structure into more accessible three-dimensional (3D) arrays. Peroxiredoxins (Prx) are a family of multitasking redox enzymes, self-assembling into ring-like architectures. Taking advantage of both their symmetric structure and function, 3D reduced GO-based composites are hereby built up. Results reveal that the "double-faced" Prx rings can adhere flat on single GO layers and partially reduce them by their sulfur-containing amino acids, driving their stacking into 3D multi-layer reduced GO-Prx composites. This process occurs in aqueous solution at a very low GO concentration, i.e. 0.2 mg ml(-1). Further, protein engineering allows the Prx ring to be enriched with metal binding sites inside its lumen. This feature is exploited to both capture presynthesized gold nanoparticles and grow in situ palladium nanoparticles paving the way to straightforward and "green" routes to 3D reduced GO-metal composite materials.

Two-dimensional Si(x)Ge(1-x) films with variable composition made via multilayer colloidal template-guided ionic liquid electrodeposition.

PubMed

Xin, Wuhong; Zhao, Jiupeng; Ge, Dengteng; Ding, Yanbo; Li, Yao; Endres, Frank

2013-02-21

The binary alloy system Si(x)Ge(1-x) provides a continuous series of materials with gradually varying properties. In this paper, we report on a fundamental basis a method to make large-area macroporous Si(x)Ge(1-x) films with variable Ge content by electrodeposition in an ionic liquid, with SiCl(4) and GeCl(4) as precursors. The chemical composition of the products can be modified by changing the molar ratio of the precursors. Periodical macroporous Si(x)Ge(1-x) was made by a multilayer polystyrene (PS) template assembled as face-centered cubic lattice. Two-dimensional (2-D) Si(x)Ge(1-x) bowl-like and fishing-net structures can be obtained by applying different deposition temperatures. The results highlight the potential applications, including photonic bandgap and battery materials, as well as ultra-thin gratings, due to the effect of modification of light and improved tunability of composition, although Si(x)Ge(1-x) made by our method is sensitive to oxidation by air.

Highly ductile multilayered films by layer-by-layer assembly of oppositely charged polyurethanes for biomedical applications.

PubMed

Podsiadlo, Paul; Qin, Ming; Cuddihy, Meghan; Zhu, Jian; Critchley, Kevin; Kheng, Eugene; Kaushik, Amit K; Qi, Ying; Kim, Hyoung-Sug; Noh, Si-Tae; Arruda, Ellen M; Waas, Anthony M; Kotov, Nicholas A

2009-12-15

Multilayered thin films prepared with the layer-by-layer (LBL) assembly technique are typically "brittle" composites, while many applications such as flexible electronics or biomedical devices would greatly benefit from ductile, and tough nanostructured coatings. Here we present the preparation of highly ductile multilayered films via LBL assembly of oppositely charged polyurethanes. Free-standing films were found to be robust, strong, and tough with ultimate strains as high as 680% and toughness of approximately 30 MJ/m(3). These results are at least 2 orders of magnitude greater than most LBL materials presented until today. In addition to enhanced ductility, the films showed first-order biocompatibility with animal and human cells. Multilayered structures incorporating polyurethanes open up a new research avenue into the preparation of multifunctional nanostructured films with great potential in biomedical applications.

Coupled multi-disciplinary simulation of composite engine structures in propulsion environment

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Singhal, Surendra N.

1992-01-01

A computational simulation procedure is described for the coupled response of multi-layered multi-material composite engine structural components which are subjected to simultaneous multi-disciplinary thermal, structural, vibration, and acoustic loadings including the effect of hostile environments. The simulation is based on a three dimensional finite element analysis technique in conjunction with structural mechanics codes and with acoustic analysis methods. The composite material behavior is assessed at the various composite scales, i.e., the laminate/ply/constituents (fiber/matrix), via a nonlinear material characterization model. Sample cases exhibiting nonlinear geometrical, material, loading, and environmental behavior of aircraft engine fan blades, are presented. Results for deformed shape, vibration frequency, mode shapes, and acoustic noise emitted from the fan blade, are discussed for their coupled effect in hot and humid environments. Results such as acoustic noise for coupled composite-mechanics/heat transfer/structural/vibration/acoustic analyses demonstrate the effectiveness of coupled multi-disciplinary computational simulation and the various advantages of composite materials compared to metals.

Optimizing Thermal-Elastic Properties of C/C–SiC Composites Using a Hybrid Approach and PSO Algorithm

PubMed Central

Xu, Yingjie; Gao, Tian

2016-01-01

Carbon fiber-reinforced multi-layered pyrocarbon–silicon carbide matrix (C/C–SiC) composites are widely used in aerospace structures. The complicated spatial architecture and material heterogeneity of C/C–SiC composites constitute the challenge for tailoring their properties. Thus, discovering the intrinsic relations between the properties and the microstructures and sequentially optimizing the microstructures to obtain composites with the best performances becomes the key for practical applications. The objective of this work is to optimize the thermal-elastic properties of unidirectional C/C–SiC composites by controlling the multi-layered matrix thicknesses. A hybrid approach based on micromechanical modeling and back propagation (BP) neural network is proposed to predict the thermal-elastic properties of composites. Then, a particle swarm optimization (PSO) algorithm is interfaced with this hybrid model to achieve the optimal design for minimizing the coefficient of thermal expansion (CTE) of composites with the constraint of elastic modulus. Numerical examples demonstrate the effectiveness of the proposed hybrid model and optimization method. PMID:28773343

Heat transfer and phase transitions of water in multi-layer cryolithozone-surface systems

NASA Astrophysics Data System (ADS)

Khabibullin, I. L.; Nigametyanova, G. A.; Nazmutdinov, F. F.

2018-01-01

A mathematical model for calculating the distribution of temperature and the dynamics of the phase transfor-mations of water in multilayer systems on permafrost-zone surface is proposed. The model allows one to perform calculations in the annual cycle, taking into account the distribution of temperature on the surface in warm and cold seasons. A system involving four layers, a snow or land cover, a top layer of soil, a layer of thermal-insulation materi-al, and a mineral soil, is analyzed. The calculations by the model allow one to choose the optimal thickness and com-position of the layers which would ensure the stability of structures built on the permafrost-zone surface.

Three-dimensional solutions for the free vibrations and buckling of thermally stressed multilayered angle-ply composite plates

NASA Technical Reports Server (NTRS)

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

1992-01-01

Analytic three-dimensional elasticity solutions are developed for the free vibration and buckling of thermally stressed rectangular multilayered angle-ply anisotropic plates which are assumed to have an antisymmetric lamination with respect to the middle plane. Sensitivity derivatives are evaluated and used to investigate the sensitivity of the vibration and buckling responses to variations in the different lamination and material parameters of the plate. A Duhamel-Neumann-type constitutive model is used, and the material properties are assumed to be independent of temperature. Numerical results are presented, showing the effects of variations in the material characteristics and fiber orientation of different layers, as well as the effect of initial thermal deformation on the vibrational and buckling responses of the plate.

Surface characteristics of spacecraft components affect the aggregation of microorganisms and may lead to different survival rates of bacteria on Mars landers.

PubMed

Schuerger, Andrew C; Richards, Jeffrey T; Hintze, Paul E; Kern, Roger G

2005-08-01

Layers of dormant endospores of Bacillus subtilis HA101 were applied to eight different spacecraft materials and exposed to martian conditions of low pressure (8.5 mbar), low temperature (-10 degrees C), and high CO(2) gas composition and irradiated with a Mars-normal ultraviolet (UV-visible- near-infrared spectrum. Bacterial layers were exposed to either 1 min or 1 h of Mars-normal UV irradiation, which simulated clear-sky conditions on equatorial Mars (0.1 tau). When exposed to 1 min of Mars UV irradiation, the numbers of viable endospores of B. subtilis were reduced three to four orders of magnitude for two brands of aluminum (Al), stainless steel, chemfilm-treated Al, clear-anodized Al, and black-anodized Al coupons. In contrast, bacterial survival was reduced only one to two orders of magnitude for endospores on the non-metal materials astroquartz and graphite composite when bacterial endospores were exposed to 1 min of Mars UV irradiation. When bacterial monolayers were exposed to 1 h of Mars UV irradiation, no viable bacteria were recovered from the six metal coupons listed above. In contrast, bacterial survival was reduced only two to three orders of magnitude for spore layers on astroquartz and graphite composite exposed to 1 h of Mars UV irradiation. Scanning electron microscopy images of the bacterial monolayers on all eight spacecraft materials revealed that endospores of B. subtilis formed large aggregates of multilayered spores on astroquartz and graphite composite, but not on the other six spacecraft materials. It is likely that the formation of multilayered aggregates of endospores on astroquartz and graphite composite is responsible for the enhanced survival of bacterial cells on these materials.

Surface characteristics of spacecraft components affect the aggregation of microorganisms and may lead to different survival rates of bacteria on Mars landers

NASA Technical Reports Server (NTRS)

Schuerger, Andrew C.; Richards, Jeffrey T.; Hintze, Paul E.; Kern, Roger G.

2005-01-01

Layers of dormant endospores of Bacillus subtilis HA101 were applied to eight different spacecraft materials and exposed to martian conditions of low pressure (8.5 mbar), low temperature (-10 degrees C), and high CO(2) gas composition and irradiated with a Mars-normal ultraviolet (UV-visible- near-infrared spectrum. Bacterial layers were exposed to either 1 min or 1 h of Mars-normal UV irradiation, which simulated clear-sky conditions on equatorial Mars (0.1 tau). When exposed to 1 min of Mars UV irradiation, the numbers of viable endospores of B. subtilis were reduced three to four orders of magnitude for two brands of aluminum (Al), stainless steel, chemfilm-treated Al, clear-anodized Al, and black-anodized Al coupons. In contrast, bacterial survival was reduced only one to two orders of magnitude for endospores on the non-metal materials astroquartz and graphite composite when bacterial endospores were exposed to 1 min of Mars UV irradiation. When bacterial monolayers were exposed to 1 h of Mars UV irradiation, no viable bacteria were recovered from the six metal coupons listed above. In contrast, bacterial survival was reduced only two to three orders of magnitude for spore layers on astroquartz and graphite composite exposed to 1 h of Mars UV irradiation. Scanning electron microscopy images of the bacterial monolayers on all eight spacecraft materials revealed that endospores of B. subtilis formed large aggregates of multilayered spores on astroquartz and graphite composite, but not on the other six spacecraft materials. It is likely that the formation of multilayered aggregates of endospores on astroquartz and graphite composite is responsible for the enhanced survival of bacterial cells on these materials.

Improved thermoelectric power output from multilayered polyethylenimine doped carbon nanotube based organic composites

NASA Astrophysics Data System (ADS)

Hewitt, Corey A.; Montgomery, David S.; Barbalace, Ryan L.; Carlson, Rowland D.; Carroll, David L.

2014-05-01

By appropriately selecting the carbon nanotube type and n-type dopant for the conduction layers in a multilayered carbon nanotube composite, the total device thermoelectric power output can be increased significantly. The particular materials chosen in this study were raw single walled carbon nanotubes for the p-type layers and polyethylenimine doped single walled carbon nanotubes for the n-type layers. The combination of these two conduction layers leads to a single thermocouple Seebeck coefficient of 96 ± 4 μVK-1, which is 6.3 times higher than that previously reported. This improved Seebeck coefficient leads to a total power output of 14.7 nW per thermocouple at the maximum temperature difference of 50 K, which is 44 times the power output per thermocouple for the previously reported results. Ultimately, these thermoelectric power output improvements help to increase the potential use of these lightweight, flexible, and durable organic multilayered carbon nanotube based thermoelectric modules in low powered electronics applications, where waste heat is available.

Cavitation resistance of surface composition "Steel-Ni-TiNi-TiNiZr-cBNCo", formed by High-Velocity Oxygen-Fuel spraying

NASA Astrophysics Data System (ADS)

Blednova, Zh. M.; Dmitrenko, D. V.; Balaev, E. U. O.

2018-01-01

The object of the study is a multilayered surface composition "Steel - a Multicomponent material with Shape Memory Effect - a wear-resistant layer" under conditions of cavitation effects in sea water. Multicomponent TiNi-based coatings with addition of alloying elements such as Zr in an amount up to 10% mass, allow to create a composite material with a gradient of properties at the interface of layers, which gives new properties to coatings and improves their performance significantly. The use of materials with shape memory effect (SME) as surface layers or in the composition of surface layered compositions allows to provide an effective reaction of materials to the influence of external factors and adaptation to external influences. The surface composite layer cBN-10%Co has high hardness and strength, which ensures its resistance to shock cyclic influences of collapsing caverns. The increased roughness of the surface of a solid surface composite in the form of strong columnar structures ensures the crushing of vacuum voids, redistributing their effect on the entire surface, and not concentrating them in certain zones. In addition, the gradient structure of the multilayer composite coating TiNi-Ti33Ni49Zr18-cBN-10%Co Co makes it possible to create conditions for the relaxation of stresses created by the variable impact load of cavitation caverns and the manifestation of compensating internal forces due to thermo-elastic martensitic transformations of SME materials. The cavitation resistance of the coating TiNi-Ti33Ni49Zr18-cBN-10%Co according to the criterion of mass wear is 15-20 times higher than that of the base material without coating and 10-12 times higher than that of the TiNi-TiNiZr coating. The proposed architecture of the multifunctional gradient composition, "steel-Ni-TiNi- Ti33Ni49Zr18-cBN-10%Co", each layer of which has its functional purpose, allows to increase the service life of parts operating under conditions of cavitation-fatigue loading in corrosive environments.

Multilayer Impregnated Fibrous Thermal Insulation Tiles

NASA Technical Reports Server (NTRS)

Tran, Huy K.; Rasky, Daniel J.; Szalai, Christine e.; Hsu, Ming-ta; Carroll, Joseph A.

2007-01-01

The term "secondary polymer layered impregnated tile" ("SPLIT") denotes a type of ablative composite-material thermal- insulation tiles having engineered, spatially non-uniform compositions. The term "secondary" refers to the fact that each tile contains at least two polymer layers wherein endothermic reactions absorb considerable amounts of heat, thereby helping to prevent overheating of an underlying structure. These tiles were invented to afford lighter-weight alternatives to the reusable thermal-insulation materials heretofore variously used or considered for use in protecting the space shuttles and other spacecraft from intense atmospheric-entry heating.

Supramolecular self-assembly of graphene oxide and metal nanoparticles into stacked multilayers by means of a multitasking protein ring

NASA Astrophysics Data System (ADS)

Ardini, Matteo; Golia, Giordana; Passaretti, Paolo; Cimini, Annamaria; Pitari, Giuseppina; Giansanti, Francesco; Leandro, Luana Di; Ottaviano, Luca; Perrozzi, Francesco; Santucci, Sandro; Morandi, Vittorio; Ortolani, Luca; Christian, Meganne; Treossi, Emanuele; Palermo, Vincenzo; Angelucci, Francesco; Ippoliti, Rodolfo

2016-03-01

Graphene oxide (GO) is rapidly emerging worldwide as a breakthrough precursor material for next-generation devices. However, this requires the transition of its two-dimensional layered structure into more accessible three-dimensional (3D) arrays. Peroxiredoxins (Prx) are a family of multitasking redox enzymes, self-assembling into ring-like architectures. Taking advantage of both their symmetric structure and function, 3D reduced GO-based composites are hereby built up. Results reveal that the ``double-faced'' Prx rings can adhere flat on single GO layers and partially reduce them by their sulfur-containing amino acids, driving their stacking into 3D multi-layer reduced GO-Prx composites. This process occurs in aqueous solution at a very low GO concentration, i.e. 0.2 mg ml-1. Further, protein engineering allows the Prx ring to be enriched with metal binding sites inside its lumen. This feature is exploited to both capture presynthesized gold nanoparticles and grow in situ palladium nanoparticles paving the way to straightforward and ``green'' routes to 3D reduced GO-metal composite materials.Graphene oxide (GO) is rapidly emerging worldwide as a breakthrough precursor material for next-generation devices. However, this requires the transition of its two-dimensional layered structure into more accessible three-dimensional (3D) arrays. Peroxiredoxins (Prx) are a family of multitasking redox enzymes, self-assembling into ring-like architectures. Taking advantage of both their symmetric structure and function, 3D reduced GO-based composites are hereby built up. Results reveal that the ``double-faced'' Prx rings can adhere flat on single GO layers and partially reduce them by their sulfur-containing amino acids, driving their stacking into 3D multi-layer reduced GO-Prx composites. This process occurs in aqueous solution at a very low GO concentration, i.e. 0.2 mg ml-1. Further, protein engineering allows the Prx ring to be enriched with metal binding sites inside its lumen. This feature is exploited to both capture presynthesized gold nanoparticles and grow in situ palladium nanoparticles paving the way to straightforward and ``green'' routes to 3D reduced GO-metal composite materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08632a

Far infrared filters for the Galileo-Jupiter and other missions

NASA Technical Reports Server (NTRS)

Seeley, J. S.; Hunneman, R.; Whatley, A.

1981-01-01

Progress in the development of FIR multilayer interference filters for the net flux radiometer and photopolarizing radiometer to be carried on board the Galileo mission to Jupiter is reported. The multilayer interference technique has been extended to the region above 40 microns by the use of PbTe/II-VI materials in hard-coated combination, with the thickest layers composed of CdSe QWOT at 74 microns and PbTe QWOT. Improvements have also been obtained in filters below 20 microns on the basis of the Chebyshev stack design. A composite filter cutting on steeply at 40 microns has been designed which employs a thin crystal quartz substrate, shorter wavelength absorption in ZnS and As2S3 thin films, and supplementary multilayer interference. Finally, absorptive filters have been developed based on II-VI compounds in multilayer combination with KRS-5 (or 6) on a KRS-5 (or 6) substrate

Graphical method to design multilayer phase retarders.

PubMed

Apfel, J H

1981-03-15

When multilayer reflectors are used at nonnormal incidence, the two planes of polarization generally have different phase shifts. This difference, known as phase retardance, depends on the multilayer design, the incidence angle, and the wavelength. Heretofore, the design of reflectors with specific phase retardance has been carried out by computer optimization except for the case of a single layer on a metal substrate. A graph of phase retardance D vs the average phase shift A as a function of layer thickness provides a means for visualization that is useful in reflector designs. A D-A graph predicts the phase properties of a reflector as a function of the index and thickness of an added layer. Graphs of phase retardance vs average phase for two different materials can be superposed to predict the composite performance of a multilayer reflector. This graphical technique is employed to design and analyze reflectors with specified phase retardance.

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.

The Behaviour of Naturally Debonded Composites Due to Bending Using a Meso-Level Model

NASA Astrophysics Data System (ADS)

Lord, C. E.; Rongong, J. A.; Hodzic, A.

2012-06-01

Numerical simulations and analytical models are increasingly being sought for the design and behaviour prediction of composite materials. The use of high-performance composite materials is growing in both civilian and defence related applications. With this growth comes the necessity to understand and predict how these new materials will behave under their exposed environments. In this study, the displacement behaviour of naturally debonded composites under out-of-plane bending conditions has been investigated. An analytical approach has been developed to predict the displacement response behaviour. The analytical model supports multi-layered composites with full and partial delaminations. The model can be used to extract bulk effective material properties in which can be represented, later, as an ESL (Equivalent Single Layer). The friction between each of the layers is included in the analytical model and is shown to have distinct behaviour for these types of composites. Acceptable agreement was observed between the model predictions, the ANSYS finite element model, and the experiments.

Combinatorial investigation of Fe–B thin-film nanocomposites

PubMed Central

Brunken, Hayo; Grochla, Dario; Savan, Alan; Kieschnick, Michael; Meijer, Jan D; Ludwig, Alfred

2011-01-01

Combinatorial magnetron sputter deposition from elemental targets was used to create Fe–B composition spread type thin film materials libraries on thermally oxidized 4-in. Si wafers. The materials libraries consisting of wedge-type multilayer thin films were annealed at 500 or 700 °C to transform the multilayers into multiphase alloys. The libraries were characterized by nuclear reaction analysis, Rutherford backscattering, nanoindentation, vibrating sample magnetometry, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Young's modulus and hardness values were related to the annealing parameters, structure and composition of the films. The magnetic properties of the films were improved by annealing in a H2 atmosphere, showing a more than tenfold decrease in the coercive field values in comparison to those of the vacuum-annealed films. The hardness values increased from 8 to 18 GPa when the annealing temperature was increased from 500 to 700 °C. The appearance of Fe2B phases, as revealed by XRD and TEM, had a significant effect on the mechanical properties of the films. PMID:27877435

High-performance asymmetric supercapacitors based on multilayer MnO2 /graphene oxide nanoflakes and hierarchical porous carbon with enhanced cycling stability.

PubMed

Zhao, Yufeng; Ran, Wei; He, Jing; Huang, Yizhong; Liu, Zhifeng; Liu, Wei; Tang, Yongfu; Zhang, Long; Gao, Dawei; Gao, Faming

2015-03-18

In this work, MnO(2)/GO (graphene oxide) composites with novel multilayer nanoflake structure, and a carbon material derived from Artemia cyst shell with genetic 3D hierarchical porous structure (HPC), are prepared. An asymmetric supercapacitor has been fabricated using MnO(2)/GO as positive electrode and HPC as negative electrode material. Because of their unique structures, both MnO(2)/GO composites and HPC exhibit excellent electrochemical performances. The optimized asymmetric supercapacitor could be cycled reversibly in the high voltage range of 0-2 V in aqueous electrolyte, which exhibits maximum energy density of 46.7 Wh kg(-1) at a power density of 100 W kg(-1) and remains 18.9 Wh kg(-1) at 2000 W kg(-1). Additionally, such device also shows superior long cycle life along with ∼100% capacitance retention after 1000 cycles and ∼93% after 4000 cycles. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An Investigation on Low Velocity Impact Response of Multilayer Sandwich Composite Structures

PubMed Central

Jedari Salami, S.; Sadighi, M.; Shakeri, M.; Moeinfar, M.

2013-01-01

The effects of adding an extra layer within a sandwich panel and two different core types in top and bottom cores on low velocity impact loadings are studied experimentally in this paper. The panel includes polymer composite laminated sheets for faces and the internal laminated sheet called extra layer sheet, and two types of crushable foams are selected as the core material. Low velocity impact tests were carried out by drop hammer testing machine to the clamped multilayer sandwich panels with expanded polypropylene (EPP) and polyurethane rigid (PUR) in the top and bottom cores. Local displacement of the top core, contact force and deflection of the sandwich panel were obtained for different locations of the internal sheet; meanwhile the EPP and PUR were used in the top and bottom cores alternatively. It was found that the core material type has made significant role in improving the sandwich panel's behavior compared with the effect of extra layer location. PMID:24453804

Multi-layer structures with thermal and acoustic properties for building rehabilitation

NASA Astrophysics Data System (ADS)

Bessa, J.; Mota, C.; Cunha, F.; Merino, F.; Fangueiro, R.

2017-10-01

This work compares the use of different sustainable materials in the design of multilayer structures for the rehabilitation of buildings in terms of thermal and acoustic properties. These structures were obtained by compression moulding and thermal and acoustic tests were further carried out for the quantification of the respective insulation properties of composite materials obtained. The experimental results show that the use of polyurethane (PUR) foams and jute fabric reinforcing biocomposites promotes interesting properties of thermal and acoustic insulation. A multi-layer structure composed by PUR foam on the intermediate layer revealed thermal resistances until 0.272 m2 K W-1. On the other hand, the use of jute fabric reinforcing biocomposites on exterior layer promoted a noise reduction at 500 Hz until 8.3 dB. These results allow to conclude that the use of PUR foams and jute fabric reinforcing biocomposites can be used successfully in rehabilitation of buildings, when the thermal and acoustic insulation is looked for.

High Temperature Multilayer Environmental Barrier Coatings Deposited Via Plasma Spray-Physical Vapor Deposition

NASA Technical Reports Server (NTRS)

Harder, Bryan James; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

2014-01-01

Si-based ceramic matrix composites (CMCs) require environmental barrier coatings (EBCs) in combustion environments to avoid rapid material loss. Candidate EBC materials have use temperatures only marginally above current technology, but the addition of a columnar oxide topcoat can substantially increase the durability. Plasma Spray-Physical Vapor Deposition (PS-PVD) allows application of these multilayer EBCs in a single process. The PS-PVD technique is a unique method that combines conventional thermal spray and vapor phase methods, allowing for tailoring of thin, dense layers or columnar microstructures by varying deposition conditions. Multilayer coatings were deposited on CMC specimens and assessed for durability under high heat flux and load. Coated samples with surface temperatures ranging from 2400-2700F and 10 ksi loads using the high heat flux laser rigs at NASA Glenn. Coating morphology was characterized in the as-sprayed condition and after thermomechanical loading using electron microscopy and the phase structure was tracked using X-ray diffraction.

Steel bonded dense silicon nitride compositions and method for their fabrication

DOEpatents

Landingham, R.L.; Shell, T.E.

1985-05-20

A two-stage bonding technique for bonding high density silicon nitride and other ceramic materials to stainless steel and other hard metals, and multilayered ceramic-metal composites prepared by the technique are disclosed. The technique involves initially slurry coating a surface of the ceramic material at about 1500/sup 0/C in a vacuum with a refractory material and the stainless steel is then pressure bonded to the metallic coated surface by brazing it with nickel-copper-silver or nickel-copper-manganese alloys at a temperature in the range of about 850/sup 0/ to 950/sup 0/C in a vacuum. The two-stage bonding technique minimizes the temperature-expansion mismatch between the dissimilar materials.

Steel bonded dense silicon nitride compositions and method for their fabrication

DOEpatents

Landingham, Richard L.; Shell, Thomas E.

1987-01-01

A two-stage bonding technique for bonding high density silicon nitride and other ceramic materials to stainless steel and other hard metals, and multilayered ceramic-metal composites prepared by the technique are disclosed. The technique involves initially slurry coating a surface of the ceramic material at about 1500.degree. C. in a vacuum with a refractory material and the stainless steel is then pressure bonded to the metallic coated surface by brazing it with nickel-copper-silver or nickel-copper-manganese alloys at a temperature in the range of about 850.degree. to 950.degree. C. in a vacuum. The two-stage bonding technique minimizes the temperature-expansion mismatch between the dissimilar materials.

Development and computer implementation of design/analysis techniques for multilayered composite structures. Probabilistic fiber composite micromechanics. M.S. Thesis, Mar. 1987 Final Report, 1 Sep. 1984 - 1 Oct. 1990

NASA Technical Reports Server (NTRS)

Stock, Thomas A.

1995-01-01

Probabilistic composite micromechanics methods are developed that simulate expected uncertainties in unidirectional fiber composite properties. These methods are in the form of computational procedures using Monte Carlo simulation. The variables in which uncertainties are accounted for include constituent and void volume ratios, constituent elastic properties and strengths, and fiber misalignment. A graphite/epoxy unidirectional composite (ply) is studied to demonstrate fiber composite material property variations induced by random changes expected at the material micro level. Regression results are presented to show the relative correlation between predictor and response variables in the study. These computational procedures make possible a formal description of anticipated random processes at the intraply level, and the related effects of these on composite properties.

Microstructure, mechanical and tribological characterization of CrN/DLC/Cr-DLC multilayer coating with improved adhesive wear resistance

NASA Astrophysics Data System (ADS)

Sui, Xudong; Liu, Jinyu; Zhang, Shuaituo; Yang, Jun; Hao, Junying

2018-05-01

Adhesive wear is one of the major reasons for the failure of components during various tribological application, especially for rubbing with viscous materials. This study presents CrN/DLC/Cr-DLC multilayer composite coatings prepared on a plasma enhanced chemical vapor deposition (PECVD) device with the close field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique. SEM, XRD and Raman spectroscopy were used to determine the structure of multilayer coatings. It was found that the multilayer coatings are composed by the alternating CrN and DLC layers. Compared with the single CrN coatings, the friction coefficient of the CrN/DLC/Cr-DLC multilayer coating decreases about more than seven times after sliding a distance of 500 m. This helps to reduce the adhesive wear of multilayer coatings. Compared with the single CrN and DLC coating, the wear rate of the CrN/DLC/Cr-DLC multilayer coating is reduced by an order of magnitude to 7.10 × 10-17 (sliding with AISI 440C) and 2.64 × 10-17 (sliding with TC4) m3/(N m). The improved tribological performance of multilayer coatings mainly attributes to the introduction of lubricant DLC and hard support CrN layers, the enhancement of crack propagation inhibition, and the increment of elastic recovery value We (71.49%) by multilayer design method.

Quantitative diagnostics of multilayered composite structures with ultrasonic guided waves

NASA Astrophysics Data System (ADS)

Bunget, Gheorghe; Friedersdorf, Fritz; Na, Jeong K.

2015-03-01

The main objective of the current work is to develop a practical nondestructive inspection methodology for a highly sound absorbing composite structural system consisting of polymeric and metallic materials. Due to constraints in geometrical shapes and thicknesses of the composite system used in this work, ultrasonic guided wave approach has been chosen. Since the polymer coatings have high damping properties, less energy is dissipated into the adjacent media in the presence of interface delaminations. Experimental measurements performed on a targeted composite system, whether it has an aluminum, carbon-fiber-composite, or steel outer casing, show promising results.

LC Circuits for Diagnosing Embedded Piezoelectric Devices

NASA Technical Reports Server (NTRS)

Chattin, Richard L.; Fox, Robert Lee; Moses, Robert W.; Shams, Qamar A.

2005-01-01

A recently invented method of nonintrusively detecting faults in piezoelectric devices involves measurement of the resonance frequencies of inductor capacitor (LC) resonant circuits. The method is intended especially to enable diagnosis of piezoelectric sensors, actuators, and sensor/actuators that are embedded in structures and/or are components of multilayer composite material structures.

Structure and tribological behavior of Pb-Ti/MoS2 nanoscaled multilayer films deposited by magnetron sputtering method

NASA Astrophysics Data System (ADS)

Li, Hao; Xie, Mingling; Zhang, Guangan; Fan, Xiaoqiang; Li, Xia; Zhu, Minhao; Wang, Liping

2018-03-01

The Pb-Ti/MoS2 nanoscaled multilayer films with different bilayer period were deposited by unbalanced magnetron sputtering system. The morphology, microstructure, mechanical and tribological properties of the films were investigated. It was found that the film changed from multilayer structure to composite structure as the bilayer period decreased from 25 nm to 6 nm, due to the diffusion effect. The multilayer film showed a pronounced (002) diffraction peak, the growth of the MoS2 platelets below the interface were affected by Pb and Ti, and the c-axis of MoS2 platelets were inclined to the substrate at an angle of -30° to 30°. The hardness of the film ranged from 5.9 to 7.2 GPa depending on the bilayer period. The tribological behavior of the films was performed under vacuum, and the friction coefficient were typically below 0.25. Furthermore, the nanoscale multilayer film with a bilayer period of 20 nm exhibits much better mechanical and tribological properties than pure MoS2. The result indicates that the nanoscale multilayer is a design methodology for developing high basal plane oriented and vacuum solid lubricating MoS2 based materials.

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 each end fitting accommodates this layer. Depending on the application, this layer could be, for example, a layer of rubber, a polymer film, or an electrodeposited layer of metal. If the fluid to be contained in the tank is a gas, then the best permeation barrier is electrodeposited metal (typically copper or nickel), which can be effective at a thickness of as little as 0.005 in (.0.13 mm). The electrodeposited metal becomes molecularly bonded to the second step on each metallic end fitting. The permeation-barrier layer is covered with many layers of filament-wound composite material, which could be the same as, or different from, the composite material of the inner shell. Finally, the filament-wound composite material is cured in an ov

Multilayer composition coatings for cutting tools: formation and performance properties

NASA Astrophysics Data System (ADS)

Tabakov, Vladimir P.; Vereschaka, Anatoly S.; Vereschaka, Alexey A.

2018-03-01

The paper considers the concept of a multi-layer architecture of the coating in which each layer has a predetermined functionality. Latest generation of coatings with multi-layered architecture for cutting tools secure a dual nature of the coating, in which coatings should not only improve the mechanical and physical characteristics of the cutting tool material, but also reduce the thermo-mechanical effect on the cutting tool determining wear intensity. Here are presented the results of the development of combined methods of forming multi-layer coatings with improved properties. Combined method of forming coatings using a pulsed laser allowed reducing excessively high levels of compressive residual stress and increasing micro hardness of the multilayered coatings. The results in testing coated HSS tools showed that the use of additional pulse of laser processing increases tool life up to 3 times. Using filtered cathodic vacuum arc deposition for the generation of multilayer coatings based on TiAlN compound has increased the wear-resistance of carbide tools by 2 fold compared with tool life of cutting tool with commercial TiN coatings. The aim of this study was to develop an innovative methodological approach to the deposition of multilayer coatings for cutting tools with functional architectural selection, properties and parameters of the coating based on sound knowledge of coating failure in machining process.

Magnetic damping phenomena in ferromagnetic thin-films and multilayers

NASA Astrophysics Data System (ADS)

Azzawi, S.; Hindmarch, A. T.; Atkinson, D.

2017-11-01

Damped ferromagnetic precession is an important mechanism underpinning the magnetisation processes in ferromagnetic materials. In thin-film ferromagnets and ferromagnetic/non-magnetic multilayers, the role of precession and damping can be critical for spintronic device functionality and as a consequence there has been significant research activity. This paper presents a review of damping in ferromagnetic thin-films and multilayers and collates the results of many experimental studies to present a coherent synthesis of the field. The terms that are used to define damping are discussed with the aim of providing consistent definitions for damping phenomena. A description of the theoretical basis of damping is presented from early developments to the latest discussions of damping in ferromagnetic thin-films and multilayers. An overview of the time and frequency domain methods used to study precessional magnetisation behaviour and damping in thin-films and multilayers is also presented. Finally, a review of the experimental observations of magnetic damping in ferromagnetic thin-films and multilayers is presented with the most recent explanations. This brings together the results from many studies and includes the effects of ferromagnetic film thickness, the effects of composition on damping in thin-film ferromagnetic alloys, the influence of non-magnetic dopants in ferromagnetic films and the effects of combining thin-film ferromagnets with various non-magnetic layers in multilayered configurations.

Improved thermoelectric power output from multilayered polyethylenimine doped carbon nanotube based organic composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hewitt, Corey A.; Montgomery, David S.; Barbalace, Ryan L.

2014-05-14

By appropriately selecting the carbon nanotube type and n-type dopant for the conduction layers in a multilayered carbon nanotube composite, the total device thermoelectric power output can be increased significantly. The particular materials chosen in this study were raw single walled carbon nanotubes for the p-type layers and polyethylenimine doped single walled carbon nanotubes for the n-type layers. The combination of these two conduction layers leads to a single thermocouple Seebeck coefficient of 96 ± 4 μVK{sup −1}, which is 6.3 times higher than that previously reported. This improved Seebeck coefficient leads to a total power output of 14.7 nW permore » thermocouple at the maximum temperature difference of 50 K, which is 44 times the power output per thermocouple for the previously reported results. Ultimately, these thermoelectric power output improvements help to increase the potential use of these lightweight, flexible, and durable organic multilayered carbon nanotube based thermoelectric modules in low powered electronics applications, where waste heat is available.« less

Graphene-Reinforced Metal and Polymer Matrix Composites

NASA Astrophysics Data System (ADS)

Kasar, Ashish K.; Xiong, Guoping; Menezes, Pradeep L.

2018-03-01

Composites have tremendous applicability due to their excellent capabilities. The performance of composites mainly depends on the reinforcing material applied. Graphene is successful as an efficient reinforcing material due to its versatile as well as superior properties. Even at very low content, graphene can dramatically improve the properties of polymer and metal matrix composites. This article reviews the fabrication followed by mechanical and tribological properties of metal and polymer matrix composites filled with different kinds of graphene, including single-layer, multilayer, and functionalized graphene. Results reported to date in literature indicate that functionalized graphene or graphene oxide-polymer composites are promising materials offering significantly improved strength and frictional properties. A similar trend of improved properties has been observed in case of graphene-metal matrix composites. However, achieving higher graphene loading with uniform dispersion in metal matrix composites remains a challenge. Although graphene-reinforced composites face some challenges, such as understanding the graphene-matrix interaction or fabrication techniques, graphene-reinforced polymer and metal matrix composites have great potential for application in various fields due to their outstanding properties.

Graphene-Reinforced Metal and Polymer Matrix Composites

NASA Astrophysics Data System (ADS)

Kasar, Ashish K.; Xiong, Guoping; Menezes, Pradeep L.

2018-06-01

Composites have tremendous applicability due to their excellent capabilities. The performance of composites mainly depends on the reinforcing material applied. Graphene is successful as an efficient reinforcing material due to its versatile as well as superior properties. Even at very low content, graphene can dramatically improve the properties of polymer and metal matrix composites. This article reviews the fabrication followed by mechanical and tribological properties of metal and polymer matrix composites filled with different kinds of graphene, including single-layer, multilayer, and functionalized graphene. Results reported to date in literature indicate that functionalized graphene or graphene oxide-polymer composites are promising materials offering significantly improved strength and frictional properties. A similar trend of improved properties has been observed in case of graphene-metal matrix composites. However, achieving higher graphene loading with uniform dispersion in metal matrix composites remains a challenge. Although graphene-reinforced composites face some challenges, such as understanding the graphene-matrix interaction or fabrication techniques, graphene-reinforced polymer and metal matrix composites have great potential for application in various fields due to their outstanding properties.

Multi-layer articles and methods of making same

DOEpatents

Fritzemeier, Leslie G.; Zhang, Wei; Palm, Walter C.; Rupich, Martin W.

2005-05-17

The invention relates to superconductor articles, and compositions and methods for making superconductor articles. The methods can include using a precursor solution having a relatively small concentration of total free acid. The articles can include more than one layer of superconductor material in which at least one layer of superconductor material can be formed by a solution process, such as a solution process involving the use of metalorganic precursors.

Carbon Nanotube-Multilayered Graphene Edge Plane Core-Shell Hybrid Foams for Ultrahigh-Performance Electromagnetic-Interference Shielding.

PubMed

Song, Qiang; Ye, Fang; Yin, Xiaowei; Li, Wei; Li, Hejun; Liu, Yongsheng; Li, Kezhi; Xie, Keyu; Li, Xuanhua; Fu, Qiangang; Cheng, Laifei; Zhang, Litong; Wei, Bingqing

2017-08-01

Materials with an ultralow density and ultrahigh electromagnetic-interference (EMI)-shielding performance are highly desirable in fields of aerospace, portable electronics, and so on. Theoretical work predicts that 3D carbon nanotube (CNT)/graphene hybrids are one of the most promising lightweight EMI shielding materials, owing to their unique nanostructures and extraordinary electronic properties. Herein, for the first time, a lightweight, flexible, and conductive CNT-multilayered graphene edge plane (MLGEP) core-shell hybrid foam is fabricated using chemical vapor deposition. MLGEPs are seamlessly grown on the CNTs, and the hybrid foam exhibits excellent EMI shielding effectiveness which exceeds 38.4 or 47.5 dB in X-band at 1.6 mm, while the density is merely 0.0058 or 0.0089 g cm -3 , respectively, which far surpasses the best values of reported carbon-based composite materials. The grafted MLGEPs on CNTs can obviously enhance the penetration losses of microwaves in foams, leading to a greatly improved EMI shielding performance. In addition, the CNT-MLGEP hybrids also exhibit a great potential as nano-reinforcements for fabricating high-strength polymer-based composites. The results provide an alternative approach to fully explore the potentials of CNT and graphene, for developing advanced multifunctional materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dental ceramics: a review of new materials and processing methods.

PubMed

Silva, Lucas Hian da; Lima, Erick de; Miranda, Ranulfo Benedito de Paula; Favero, Stéphanie Soares; Lohbauer, Ulrich; Cesar, Paulo Francisco

2017-08-28

The evolution of computerized systems for the production of dental restorations associated to the development of novel microstructures for ceramic materials has caused an important change in the clinical workflow for dentists and technicians, as well as in the treatment options offered to patients. New microstructures have also been developed by the industry in order to offer ceramic and composite materials with optimized properties, i.e., good mechanical properties, appropriate wear behavior and acceptable aesthetic characteristics. The objective of this literature review is to discuss the main advantages and disadvantages of the new ceramic systems and processing methods. The manuscript is divided in five parts: I) monolithic zirconia restorations; II) multilayered dental prostheses; III) new glass-ceramics; IV) polymer infiltrated ceramics; and V) novel processing technologies. Dental ceramics and processing technologies have evolved significantly in the past ten years, with most of the evolution being related to new microstructures and CAD-CAM methods. In addition, a trend towards the use of monolithic restorations has changed the way clinicians produce all-ceramic dental prostheses, since the more aesthetic multilayered restorations unfortunately are more prone to chipping or delamination. Composite materials processed via CAD-CAM have become an interesting option, as they have intermediate properties between ceramics and polymers and are more easily milled and polished.

Determination of the mechanical indices of composite materials by testing multilayered samples

NASA Astrophysics Data System (ADS)

Teregulov, I. G.; Kayumov, R. A.; Butenko, Yu. I.; Safiullin, D. Kh.

1996-09-01

The mechanical indices of materials such as composites reinforced by braids and ribbons are difficult to determine by standard methods. Moreover, the indices of such materials may be greatly altered when they are converted into various structures. It has been suggested that these indices be determined by analyzing the structure testing data. The determination of linear and nonlinear elastic, plastic, and viscoelastic parameters of reinforced materials is discussed. A very simple structure, namely, cylindrical shells made by symmetric winding, is studied as an example. Equilibrium conditions are used to obtain resolving equations relative to the mechanical indices. Convergence of iteration methods is examined. The effect of the scatter of experimental data on the calculated results is analyzed.

Detection of defects in multi-layered aramid composites by ultrasonic IR thermography

NASA Astrophysics Data System (ADS)

Pracht, Monika; Swiderski, Waldemar

2017-10-01

In military applications, laminates reinforced with aramid, carbon, and glass fibers are used for the construction of protection products against light ballistics. Material layers can be very different by their physical properties. Therefore, such materials represent a difficult inspection task for many traditional techniques of non-destructive testing (NDT). Defects which can appear in this type of many-layered composite materials usually are inaccuracies in gluing composite layers and stratifications or delaminations occurring under hits of fragments and bullets. IR thermographic NDT is considered as a candidate technique to detect such defects. One of the active IR thermography methods used in nondestructive testing is vibrothermography. The term vibrothermography was created in the 1990s to determine the thermal test procedures designed to assess the hidden heterogeneity of structural materials based on surface temperature fields at cyclical mechanical loads. A similar procedure can be done with sound and ultrasonic stimulation of the material, because the cause of an increase in temperature is internal friction between the wall defect and the stimulation mechanical waves. If the cyclic loading does not exceed the flexibility of the material and the rate of change is not large, the heat loss due to thermal conductivity is small, and the test object returns to its original shape and temperature. The most commonly used method is ultrasonic stimulation, and the testing technique is ultrasonic infrared thermography. Ultrasonic IR thermography is based on two basic phenomena. First, the elastic properties of defects differ from the surroundings, and acoustic damping and heating are always larger in the damaged regions than in the undamaged or homogeneous areas. Second, the heat transfer in the sample is dependent on its thermal properties. In this paper, both modelling and experimental results which illustrate the advantages and limitations of ultrasonic IR thermography in inspecting multi-layered aramide composite materials will be presented.

TOPICAL REVIEW: Progress in engineering high strain lead-free piezoelectric ceramics

NASA Astrophysics Data System (ADS)

Leontsev, Serhiy O.; Eitel, Richard E.

2010-08-01

Environmental concerns are strongly driving the need to replace the lead-based piezoelectric materials currently employed as multilayer actuators. The current review describes both compositional and structural engineering approaches to achieve enhanced piezoelectric properties in lead-free materials. The review of the compositional engineering approach focuses on compositional tuning of the properties and phase behavior in three promising families of lead-free perovskite ferroelectrics: the titanate, alkaline niobate and bismuth perovskites and their solid solutions. The 'structural engineering' approaches focus instead on optimization of microstructural features including grain size, grain orientation or texture, ferroelectric domain size and electrical bias field as potential paths to induce large piezoelectric properties in lead-free piezoceramics. It is suggested that a combination of both compositional and novel structural engineering approaches will be required in order to realize viable lead-free alternatives to current lead-based materials for piezoelectric actuator applications.

Progress in engineering high strain lead-free piezoelectric ceramics

PubMed Central

Leontsev, Serhiy O; Eitel, Richard E

2010-01-01

Environmental concerns are strongly driving the need to replace the lead-based piezoelectric materials currently employed as multilayer actuators. The current review describes both compositional and structural engineering approaches to achieve enhanced piezoelectric properties in lead-free materials. The review of the compositional engineering approach focuses on compositional tuning of the properties and phase behavior in three promising families of lead-free perovskite ferroelectrics: the titanate, alkaline niobate and bismuth perovskites and their solid solutions. The ‘structural engineering’ approaches focus instead on optimization of microstructural features including grain size, grain orientation or texture, ferroelectric domain size and electrical bias field as potential paths to induce large piezoelectric properties in lead-free piezoceramics. It is suggested that a combination of both compositional and novel structural engineering approaches will be required in order to realize viable lead-free alternatives to current lead-based materials for piezoelectric actuator applications. PMID:27877343

FEM-based strain analysis study for multilayer sheet forming process

NASA Astrophysics Data System (ADS)

Zhang, Rongjing; Lang, Lihui; Zafar, Rizwan

2015-12-01

Fiber metal laminates have many advantages over traditional laminates (e.g., any type of fiber and resin material can be placed anywhere between the metallic layers without risk of failure of the composite fabric sheets). Furthermore, the process requirements to strictly control the temperature and punch force in fiber metal laminates are also less stringent than those in traditional laminates. To further explore the novel method, this study conducts a finite element method-based (FEM-based) strain analysis on multilayer blanks by using the 3A method. Different forming modes such as wrinkling and fracture are discussed by using experimental and numerical studies. Hydroforming is used for multilayer forming. The Barlat 2000 yield criteria and DYNAFORM/LS-DYNA are used for the simulations. Optimal process parameters are determined on the basis of fixed die-binder gap and variable cavity pressure. The results of this study will enhance the knowledge on the mechanics of multilayer structures formed by using the 3A method and expand its commercial applications.

An Experimental Study on Slurry Erosion Resistance of Single and Multilayered Deposits of Ni-WC Produced by Laser-Based Powder Deposition Process

NASA Astrophysics Data System (ADS)

Balu, Prabu; Hamid, Syed; Kovacevic, Radovan

2013-11-01

Single and multilayered deposits containing different mass fractions of tungsten carbide (WC) in nickel (Ni)-matrix (NT-20, NT-60, NT-80) are deposited on a AISI 4140 steel substrate using a laser-based powder deposition process. The transverse cross section of the coupons reveals that the higher the mass fraction of WC in Ni-matrix leads to a more uniform distribution through Ni-matrix. The slurry erosion resistance of the fabricated coupons is tested at three different impingement angles using an abrasive water jet cutting machine, which is quantified based on the erosion rate. The top layer of a multilayered deposit (i.e., NT-60 in a two-layer NT-60 over NT-20 deposit) exhibits better erosion resistance at all three tested impingement angles when compared to a single-layer (NT-60) deposit. A definite increase in the erosion resistance is noted with an addition of nano-size WC particles. The relationship between the different mass fractions of reinforcement (WC) in the deposited composite material (Ni-WC) and their corresponding matrix (Ni) hardness on the erosion rate is studied. The eroded surface is analyzed in the light of a three-dimensional (3-D) profilometer and a scanning electron microscope (SEM). The results show that a volume fraction of approximately 62% of WC with a Ni-matrix hardness of 540 HV resulting in the gouging out of WC from the Ni-matrix by the action of slurry. It is concluded that the slurry erosion resistance of the AISI 4140 steel can be significantly enhanced by introducing single and multilayered deposits of Ni-WC composite material fabricated by the laser-based powder deposition process.

Ceramic insulation/multifoil composite for thermal protection of reentry spacecraft

NASA Technical Reports Server (NTRS)

Pitts, W. C.; Kourtides, D. A.

1989-01-01

A new type of insulation blanket called Composite Flexible Blanket Insulation is proposed for thermal protection of advanced spacecraft in regions where the maximum temperature is not excessive. The blanket is a composite of two proven insulation materials: ceramic insulation blankets from Space Shuttle technology and multilayer insulation blankets from spacecraft thermal control technology. A potential heatshield weight saving of up to 500 g/sq m is predicted. The concept is described; proof of concept experimental data are presented; and a spaceflight experiment to demonstrate its actual performance is discussed.

Synthesis and processing of nanostructured BN and BN/Ti composites

NASA Astrophysics Data System (ADS)

Horvath, Robert Steven

Superhard materials, such as cubic-BN, are widely used in machine tools, grinding wheels, and abrasives. Low density combined with high hardness makes c-BN and its composites attractive candidate materials for personnel and vehicular armor. However, improvements in toughness, and ballistic-impact performance, are needed to meet anticipated performance requirements. To achieve such improvements, we have targeted for development nanostructured c-BN, and its composites with Ti. Current research utilizes an experimental high pressure/high temperature (HPHT) method to produce these materials on a laboratory scale. Results from this work should transfer well into the industrial arena, utilizing high-tonnage presses used in the production of synthetic diamond and c-BN. Progress has been made in: (1) HPHT synthesis of cBN powder using Mg as catalyst; (2) HPHT consolidation of cBN powder to produce nanostructured cBN; (3) reactive-HPHT consolidation of mixed cBN/Ti powder to produce nanostructured Ti- or TiB2/TiN-bonded cBN; and (4) reactive-HPHT consolidation of mixed hBN/Ti powder to produce nanostructured Ti-bonded TiB2/TiN or TiB2/TiN. Even so, much remains to be done to lay a firm scientific foundation to enable the reproducible fabrication of large-area panels for armor applications. To this end, Rutgers has formed a partnership with a major producer of hard and superhard materials. The ability to produce hard and superhard nanostructured composites by reacting cBN or hBN with Ti under high pressure also enables multi-layered structures to be developed. Such structures may be designed to satisfy impedance-mismatch requirements for high performance armor, and possibly provide a multi-hit capability. A demonstration has been made of reactive-HPHT processing of multi-layered composites, consisting of alternating layers of superhard Ti-bonded cBN and tough Ti. It is noteworthy that the pressure requirements for processing Ti-bonded cBN, Ti-bonded TiB2/TiN, and their corresponding multi-layered structures are in the 0.1-1.0 GPa range, well within the capabilities of today's hot-pressing technologies; thus scaling this new reactive-HPHT processing technology seems assured. Future research will focus on establishing mechanisms and kinetics of the various phase transformations observed during reactive-HPHT processing, with the objective of being able to optimize processing parameters to generate nanostructured cBN-based and TiB2/TiN-based composites that display superior mechanical properties, particularly under high-strain-rate conditions.

Tailor-Made Electrospun Multilayer Composite Polymer Electrolytes for High-Performance Lithium Polymer Batteries.

PubMed

Lim, Du-Hyun; Haridas, Anupriya K; Figerez, Stelbin Peter; Raghavan, Prasanth; Matic, Aleksandar; Ahn, Jou-Hyeon

2018-09-01

A novel tailor-made multilayer composite polymer electrolyte, consisting of two outer layers of electrospun polyacrylonitrile (PAN) and one inner layer of poly(vinyl acetate) (PVAc)/poly(methyl methacrylate) (PMMA)/poly(ethylene oxide) (PEO) fibrous membrane, was prepared using continuous electrospinning. These membranes, which are made up of fibers with diameters in the nanometer range, were stacked in layers to produce interconnected pores that result in a high porosity. Gel polymer electrolytes (GPEs) were prepared by entrapping a liquid electrolyte (1 M LiPF6 in ethylene carbonate/dimethyl carbonate) in the membranes. The composite membranes exhibited a high electrolyte uptake of 450-510%, coupled with an improved room temperature ionic conductivity of up to 4.72 mS cm-1 and a high electrochemical stability of 4.6 V versus Li/Li+. Electrochemical investigations of a composite membrane of PAN-PVAc-PAN, with a LiFePO4 cathode synthesized in-house, showed a high initial discharge capacity of 145 mAh g-1, which corresponds to 85% utilization of the active material, and displayed stable cycle performance.

Advanced electromagnetic methods for aerospace vehicles

NASA Technical Reports Server (NTRS)

Balanis, Constantine A.; Sun, Weimin; El-Sharawy, El-Budawy; Aberle, James T.; Birtcher, Craig R.; Peng, Jian; Tirkas, Panayiotis A.

1992-01-01

The Advanced Helicopter Electromagnetics (AHE) Industrial Associates Program continues its research on variety of main topics identified and recommended by the Advisory Task Force of the program. The research activities center on issues that advance technology related to helicopter electromagnetics. While most of the topics are a continuation of previous works, special effort has been focused on some of the areas due to recommendations from the last annual conference. The main topics addressed in this report are: composite materials, and antenna technology. The area of composite materials continues getting special attention in this period. The research has focused on: (1) measurements of the electrical properties of low-conductivity materials; (2) modeling of material discontinuity and their effects on the scattering patterns; (3) preliminary analysis on interaction of electromagnetic fields with multi-layered graphite fiberglass plates; and (4) finite difference time domain (FDTD) modeling of fields penetration through composite panels of a helicopter.

A simple design of an artificial electromagnetic black hole

NASA Astrophysics Data System (ADS)

Lu, Wanli; Jin, JunFeng; Lin, Zhifang; Chen, Huanyang

2010-09-01

We conduct a rigorous study on the properties of an artificial electromagnetic black hole for transverse magnetic modes. A multilayered structure of such a black hole is then proposed as a reduced variety for easy experimental implementations. An actual design of composite materials based on the effective medium theory is given with only five kinds of real isotropic materials. The finite element method confirms the functionality of such a simple design.

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.

On a high-potential variable flexural stiffness device

NASA Astrophysics Data System (ADS)

Henke, Markus; Gerlach, Gerald

2013-05-01

There are great efforts in developing effective composite structures for lightweight constructions for nearly every field of engineering. This concerns for example aeronautics and spacecrafts, but also automotive industry and energy harvesting applications. Modern concepts of lightweight components try to make use of structures with properties which can be adjusted in a controllable was. However, classic composite materials can only slightly adapt to varying environmental conditions because most materials, like carbon or glass-fiber composites show properties which are time-constant and not changeable. This contribution describes the development, the potential and the limitations of novel smart, self-controlling structures which can change their mechanical properties - e.g. their flexural stiffness - by more then one order of magnitude. These structures use a multi-layer approach with a 10-layer stack of 0.75 mm thick polycarbonate. The set-up is analytically described and its mechanical behavior is predicted by finite element analysis done with ABAQUS. The layers are braided together by an array of shape memory alloy (SMA) wires, which can be activated independently. Depending on the temperature applied by the electrical current flowing through the wires and the corresponding contraction the wires can tightly clamp the layers so that they cannot slide against each other due to friction forces. In this case the multilayer acts as rigid beam with high stiffness. If the friction-induced shear stress is smaller than a certain threshold, then the layers can slide over each other and the multilayer becomes compliant under bending load. The friction forces between the layers and, hence, the stiffness of the beam is controlled by the electrical current through the wires. The more separate parts of SMA wires the structure has the larger is the number of steps of stiffness changes of the flexural beam.

Advanced Multilayer Composite Heavy-Oxide Scintillator Detectors for High Efficiency Fast Neutron Detection

NASA Astrophysics Data System (ADS)

Ryzhikov, Vladimir D.; Naydenov, Sergei V.; Pochet, Thierry; Onyshchenko, Gennadiy M.; Piven, Leonid A.; Smith, Craig F.

2018-01-01

We have developed and evaluated a new approach to fast neutron and neutron-gamma detection based on large-area multilayer composite heterogeneous detection media consisting of dispersed granules of small-crystalline scintillators contained in a transparent organic (plastic) matrix. Layers of the composite material are alternated with layers of transparent plastic scintillator material serving as light guides. The resulting detection medium - designated as ZEBRA - serves as both an active neutron converter and a detection scintillator which is designed to detect both neutrons and gamma-quanta. The composite layers of the ZEBRA detector consist of small heavy-oxide scintillators in the form of granules of crystalline BGO, GSO, ZWO, PWO and other materials. We have produced and tested the ZEBRA detector of sizes 100x100x41 mm and greater, and determined that they have very high efficiency of fast neutron detection (up to 49% or greater), comparable to that which can be achieved by large sized heavy-oxide single crystals of about Ø40x80 cm3 volume. We have also studied the sensitivity variation to fast neutron detection by using different types of multilayer ZEBRA detectors of 100 cm2 surface area and 41 mm thickness (with a detector weight of about 1 kg) and found it to be comparable to the sensitivity of a 3He-detector representing a total cross-section of about 2000 cm2 (with a weight of detector, including its plastic moderator, of about 120 kg). The measured count rate in response to a fast neutron source of 252Cf at 2 m for the ZEBRA-GSO detector of size 100x100x41 mm3 was 2.84 cps/ng, and this count rate can be doubled by increasing the detector height (and area) up to 200x100 mm2. In summary, the ZEBRA detectors represent a new type of high efficiency and low cost solid-state neutron detector that can be used for stationary neutron/gamma portals. They may represent an interesting alternative to expensive, bulky gas counters based on 3He or 10B neutron detection technologies.

Multilayer Insulation Material Guidelines

NASA Technical Reports Server (NTRS)

Finckenor, M. M.; Dooling, D.

1999-01-01

Multilayer Insulation Material Guidelines provides data on multilayer insulation materials used by previous spacecraft such as Spacelab and the Long-Duration Exposure Facility and outlines other concerns. The data presented in the document are presented for information only. They can be used as guidelines for multilayer insulation design for future spacecraft provided the thermal requirements of each new design and the environmental effects on these materials are taken into account.

Facile solvothermal synthesis of NaTi2(PO4)3/C porous plates as electrode materials for high-performance sodium ion batteries

NASA Astrophysics Data System (ADS)

Huang, Zhifeng; Liu, Li; Yi, Lingguang; Xiao, Wei; Li, Min; Zhou, Qian; Guo, Guoxiong; Chen, Xiaoying; Shu, Hongbo; Yang, Xiukang; Wang, Xianyou

2016-09-01

NaTi2(PO4)3/C porous plates have been successfully synthesized via solvothermal approach with ammonia as inductive agent combined in-situ carbon coating. It reveals that the inductive agent plays a critical role in morphology-controllable fabrication. The morphology, structure, and electrochemical properties of NaTi2(PO4)3/C composites with multilayered plates, single-layered plate, porous multilayered plates all have been investigated, which are prepared by using urea, triethylamine, and ammonia, respectively. Among these samples, NaTi2(PO4)3/C porous multilayered plates with ammonia addition exhibit the best electrochemical properties due to their unique mesoporous structure. NaTi2(PO4)3/C porous multilayered plates deliver an initial specific capacity of 125 and 110 mAh g-1 at 0.1 and 1 C, respectively. Furthermore, NaTi2(PO4)3/C porous multilayered plates show a good rate capability, whose capacity and corresponding capacity retention reach 85 mAh g-1 and 82.4%, respectively, after 120 cycles under the high rate of 10 C. The excellent results indicate that the NaTi2(PO4)3/C porous multilayered plates are a promising electrode candidate for sodium ion battery.

Three-dimensional solutions for the thermal buckling and sensitivity derivatives of temperature-sensitive multilayered angle-ply plates

NASA Technical Reports Server (NTRS)

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

1992-01-01

Analytic three-dimensional thermoelasticity solutions are presented for the thermal buckling of multilayered angle-ply composite plates with temperature-dependent thermoelastic properties. Both the critical temperatures and the sensitivity derivatives are computed. The sensitivity derivatives measure the sensitivity of the buckling response to variations in the different lamination and material parameters of the plate. The plates are assumed to have rectangular geometry and an antisymmetric lamination with respect to the middle plane. The temperature is assumed to be independent of the surface coordinates, but has an arbitrary symmetric variation through the thickness of the plate. The prebuckling deformations are accounted for. Numerical results are presented, for plates subjected to uniform temperature increase, showing the effects of temperature-dependent material properties on the prebuckling stresses, critical temperatures, and their sensitivity derivatives.

Hazards protection for space suits and spacecraft

NASA Technical Reports Server (NTRS)

Kosmo, Joseph J. (Inventor); Dawn, Frederic S. (Inventor)

1990-01-01

A flexible multi-layered covering article for protection against the hazards of exposure to the environment of outer space is disclosed. The covering includes an outer layer section comprising an outermost lamina of woven expanded tetrafluoroethylene yarns (Gore Tex) for protecting against abrasion and tearing, an underlying weave of meta-aramid yarns (Nomex) and para-aramid yarns (Kevlar) for particle impart protection, and electrostatic charge dissipation and control system incorporated therein, and a chemical contaminants control barrier applied as a coating. A middle section includes a succession of thermal insulating layers of polymeric thermoplastic or thermoforming material, each of which is coated with a metal deposit of high infra-red emissivity and low solar radiation absorption characteristics and separated from adjacent insulating layers by a low thermal conductance material. The covering further includes a radiation attenuating layer of a tungsten-loaded polymeric elastomer binder for protecting against bremsstrahlung radiation and an inner layer of rip-stop polyester material for abrasion protection. A chloroprene coating may be supplied the polyester-material for added micrometeroid protection. Securing means of low heat conductance material secures the multi-layers together as a laminar composite.

Compositionally Graded Multilayer Ceramic Capacitors.

PubMed

Song, Hyun-Cheol; Zhou, Jie E; Maurya, Deepam; Yan, Yongke; Wang, Yu U; Priya, Shashank

2017-09-27

Multilayer ceramic capacitors (MLCC) are widely used in consumer electronics. Here, we provide a transformative method for achieving high dielectric response and tunability over a wide temperature range through design of compositionally graded multilayer (CGML) architecture. Compositionally graded MLCCs were found to exhibit enhanced dielectric tunability (70%) along with small dielectric losses (<2.5%) over the required temperature ranges specified in the standard industrial classifications. The compositional grading resulted in generation of internal bias field which enhanced the tunability due to increased nonlinearity. The electric field tunability of MLCCs provides an important avenue for design of miniature filters and power converters.

Characterisation of anti-erosive properties of nanocomposite coatings by the methods of sclerometry

NASA Astrophysics Data System (ADS)

Kudryakov, O. V.; Varavka, V. N.; Ilyasov, V. V.

2017-05-01

Results of research of coatings of the different metal-ceramics systems are given. Coatings were received by ion-plasma sedimentation in vacuum in the form of multilayered composite material, which had a thickness of layers within nanometric range. Selection of composite systems is determined by applied research problem - namely designing of the anti-erosive coatings durable in the condition of drop impingement impacts. For this purpose the sclerometric studies, the bench erosive tests and optimization of the obtained data were done.

MUSIC imaging method for electromagnetic inspection of composite multi-layers

NASA Astrophysics Data System (ADS)

Rodeghiero, Giacomo; Ding, Ping-Ping; Zhong, Yu; Lambert, Marc; Lesselier, Dominique

2015-03-01

A first-order asymptotic formulation of the electric field scattered by a small inclusion (with respect to the wavelength in dielectric regime or to the skin depth in conductive regime) embedded in composite material is given. It is validated by comparison with results obtained using a Method of Moments (MoM). A non-iterative MUltiple SIgnal Classification (MUSIC) imaging method is utilized in the same configuration to locate the position of small defects. The effectiveness of the imaging algorithm is illustrated through some numerical examples.

Ultra-thin layer packaging for implantable electronic devices

NASA Astrophysics Data System (ADS)

Hogg, A.; Aellen, T.; Uhl, S.; Graf, B.; Keppner, H.; Tardy, Y.; Burger, J.

2013-07-01

State of the art packaging for long-term implantable electronic devices generally uses reliable metal and glass housings; however, these are limited in the miniaturization potential and cost reduction. This paper focuses on the development of biocompatible hermetic thin-film packaging based on poly-para-xylylene (Parylene-C) and silicon oxide (SiOx) multilayers for smart implantable microelectromechanical systems (MEMS) devices. For the fabrication, a combined Parylene/SiOx single-chamber deposition system was developed. Topological aspects of multilayers were characterized by atomic force microscopy and scanning electron microscopy. Material compositions and layer interfaces were analyzed by Fourier transform infrared spectrometry and x-ray photoelectron spectroscopy. To evaluate the multilayer corrosion protection, water vapor permeation was investigated using a calcium mirror test. The calcium mirror test shows very low water permeation rates of 2 × 10-3 g m-2 day-1 (23 °C, 45% RH) for a 4.7 µm multilayer, which is equivalent to a 1.9 mm pure Parylene-C coating. According to the packaging standard MIL-STD-883, the helium gas tightness was investigated. These helium permeation measurements predict that a multilayer of 10 µm achieves the hermeticity acceptance criterion required for long-term implantable medical devices.

Ferroelectric-ferromagnetic multilayers: A magnetoelectric heterostructure with high output charge signal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prokhorenko, S.; Kohlstedt, H.; Pertsev, N. A., E-mail: pertsev.domain@mail.ioffe.ru

2014-09-21

Multiferroic composites and heterostructures comprising ferroelectric and ferromagnetic materials exhibit room-temperature magnetoelectric (ME) effects greatly exceeding those of single-phase magnetoelectrics known to date. Since these effects are mediated by the interfacial coupling between ferroic constituents, the ME responses may be enhanced by increasing the density of interfaces and improving their quality. A promising material system providing these features is a ferroelectric-ferromagnetic multilayer with epitaxial interfaces. In this paper, we describe theoretically the strain-mediated direct ME effect exhibited by free-standing multilayers composed of single-crystalline ferroelectric nanolayers interleaved by conducting ferromagnetic slabs. Using a nonlinear thermodynamic approach allowing for specific mechanical boundarymore » conditions of the problem, we first calculate the polarization states and dielectric properties of ferroelectric nanolayers in dependence on the lattice mismatch between ferroic constituents and their volume fractions. In these calculations, the ferromagnetic component is described by a model which combines linear elastic behavior with magnetic-field-dependent lattice parameters. Then the quasistatic ME polarization and voltage coefficients are evaluated using the theoretical strain sensitivity of ferroelectric polarization and measured effective piezomagnetic coefficients of ferromagnets. For Pb(Zr₀.₅Ti₀.₅)O₃-FeGaB and BaTiO₃-FeGaB multilayers, the ME coefficients are calculated numerically as a function of the FeGaB volume fraction and used to evaluate the output charge and voltage signals. It is shown that the multilayer geometry of a ferroelectric-ferromagnetic nanocomposite opens the way for a drastic enhancement of the output charge signal. This feature makes biferroic multilayers advantageous for the development of ultrasensitive magnetic-field sensors for technical and biomedical applications.« less

Tribological Performance of Ni3Al Matrix Self-Lubricating Composites Containing Multilayer Graphene Prepared by Additive Manufacturing

NASA Astrophysics Data System (ADS)

Yan, Zhao; Shi, Xiaoliang; Huang, Yuchun; Deng, Xiaobin; Liu, Xiyao; Yang, Kang

2018-01-01

In order to improve tribological performance of Ni3Al-based alloy, Ni3Al matrix composites containing 1.5 wt.% multilayer graphene (MLG) are prepared through additive manufacturing (AM) and spark plasma sintering (SPS), which are denoted as NMAM and NMSPS, respectively. Tribological behaviors of NMAM and NMSPS against Si3N4 balls are researched under constant speed (0.2 m/s) and varied loads (from 4 to 16 N) for evaluating the tribological properties of NMAM and NMSPS. The results present that NMAM exhibits the excellent tribological properties [low friction coefficients (0.26-0.40) and considerable wear resistance (2.8-4.6 × 10-5 mm3 N-1 m-1)] as compared to NMSPS, which attributes to the uniform enrichment of MLG with properties of high tensile strength and being easily sheared off on the worn surfaces. Owing to the use of spherical prealloyed powder containing multilayer graphene and the characteristics of layer by layer depositing in the AM process, NMAM has a more compact and uniform substrate, which persistently provides a source of the formation of continuous and stable frictional layer. Due to the characteristics of AM rapid solidification, NMAM has the small grain size and well-compacted microstructure, which can effectively reduce the probability of spalling wear and lead to the increase in wear resistance of materials. The research can offer the reference for self-lubricating materials prepared by AM technology.

Disentangling the co-structure of multilayer interaction networks: degree distribution and module composition in two-layer bipartite networks.

PubMed

Astegiano, Julia; Altermatt, Florian; Massol, François

2017-11-13

Species establish different interactions (e.g. antagonistic, mutualistic) with multiple species, forming multilayer ecological networks. Disentangling network co-structure in multilayer networks is crucial to predict how biodiversity loss may affect the persistence of multispecies assemblages. Existing methods to analyse multilayer networks often fail to consider network co-structure. We present a new method to evaluate the modular co-structure of multilayer networks through the assessment of species degree co-distribution and network module composition. We focus on modular structure because of its high prevalence among ecological networks. We apply our method to two Lepidoptera-plant networks, one describing caterpillar-plant herbivory interactions and one representing adult Lepidoptera nectaring on flowers, thereby possibly pollinating them. More than 50% of the species established either herbivory or visitation interactions, but not both. These species were over-represented among plants and lepidopterans, and were present in most modules in both networks. Similarity in module composition between networks was high but not different from random expectations. Our method clearly delineates the importance of interpreting multilayer module composition similarity in the light of the constraints imposed by network structure to predict the potential indirect effects of species loss through interconnected modular networks.

Nanoscale deformation mechanism of TiC/a-C nanocomposite thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C. Q.; Pei, Y. T.; Shaha, K. P.

2009-06-01

This paper concentrates on the deformation behavior of amorphous diamondlike carbon composite materials. Combined nanoindentation and ex situ cross-sectional transmission electron microscopy investigations are carried out on TiC/a-C nanocomposite films, with and without multilayered structures deposited by pulse dc magnetron sputtering. It is shown that by controlling the distribution of nanocrystallites forming nanoscale multilayers, the system can be used as a 'microstructural ruler' that is able to distinguish various deformation patterns, which can be hardly detected otherwise in a homogeneous structure. It is shown that rearrangement of nanocrystallites and displacement of a-C matrix occur at length scales from tens ofmore » nanometer down to 1 nm. At submicrometer scale homogeneous nucleation of multiple shear bands has been observed within the nanocomposites. The multilayered structure in the TiC/a-C nanocomposite film contributes to an enhanced toughness.« less

Materials Development for Hypersonic Flight Vehicles

NASA Technical Reports Server (NTRS)

Glass, David E.; Dirling, Ray; Croop, Harold; Fry, Timothy J.; Frank, Geoffrey J.

2006-01-01

The DARPA/Air Force Falcon program is planning to flight test several hypersonic technology vehicles (HTV) in the next several years. A Materials Integrated Product Team (MIPT) was formed to lead the development of key thermal protection system (TPS) and hot structures technologies. The technologies being addressed by the MIPT are in the following areas: 1) less than 3000 F leading edges, 2) greater than 3000 F refractory composite materials, 3) high temperature multi-layer insulation, 4) acreage TPS, and 5) high temperature seals. Technologies being developed in each of these areas are discussed in this paper.

Compositionally Graded Multilayer Ceramic Capacitors

DOE PAGES

Song, Hyun-Cheol; Zhou, Jie E.; Maurya, Deepam; ...

2017-09-27

Multilayer ceramic capacitors (MLCC) are widely used in consumer electronics. In this paper, we provide a transformative method for achieving high dielectric response and tunability over a wide temperature range through design of compositionally graded multilayer (CGML) architecture. Compositionally graded MLCCs were found to exhibit enhanced dielectric tunability (70%) along with small dielectric losses (<2.5%) over the required temperature ranges specified in the standard industrial classifications. The compositional grading resulted in generation of internal bias field which enhanced the tunability due to increased nonlinearity. The electric field tunability of MLCCs provides an important avenue for design of miniature filters andmore » power converters.« less

Thermal Performance Testing of Order Dependancy of Aerogels Multilayered Insulation

NASA Technical Reports Server (NTRS)

Johnson, Wesley L.; Fesmire, James E.; Demko, J. A.

2009-01-01

Robust multilayer insulation systems have long been a goal of many research projects. Such insulation systems must provide some degree of structural support and also mechanical integrity during loss of vacuum scenarios while continuing to provide insulative value to the vessel. Aerogel composite blankets can be the best insulation materials in ambient pressure environments; in high vacuum, the thermal performance of aerogel improves by about one order of magnitude. Standard multilayer insulation (MU) is typically 50% worse at ambient pressure and at soft vacuum, but as much as two or three orders of magnitude better at high vacuum. Different combinations of aerogel and multilayer insulation systems have been tested at Cryogenics Test Laboratory of NASA Kennedy Space Center. Analysis performed at Oak Ridge National Laboratory showed an importance to the relative location of the MU and aerogel blankets. Apparent thermal conductivity testing under cryogenic-vacuum conditions was performed to verify the analytical conclusion. Tests results are shown to be in agreement with the analysis which indicated that the best performance is obtained with aerogel layers located in the middle of the blanket insulation system.

Stress Compensating Multilayers

NASA Technical Reports Server (NTRS)

Broadway, David M.; Ramsey, Brian D.; O'dell, Stephen; Gurgew, Danielle

2017-01-01

We present in-situ stress measurement results for single and multilayer thin-films deposited by magnetron sputtering. In particular, we report on the influence of the material interfaces on the ensuing stress in both the transient and steady-state regimes of film growth. This behavior is used to determine the appropriate thicknesses of the constituent layers that will result in a net tensile stress in multilayers composed of various material combinations. These multilayers can then be used to compensate the compressive integrated stress in single and multilayer EUV and x-ray optical coatings. The use of multilayers to compensate the integrated stress might be advantageous because, unlike single layers of chromium, the roughness is not expected to increase with the total thickness of the multilayer. In this paper, we demonstrate the technique for W/Si and Mo/Si multilayers and discuss its application to other material combinations.

Multi-layer imager design for mega-voltage spectral imaging

NASA Astrophysics Data System (ADS)

Myronakis, Marios; Hu, Yue-Houng; Fueglistaller, Rony; Wang, Adam; Baturin, Paul; Huber, Pascal; Morf, Daniel; Star-Lack, Josh; Berbeco, Ross

2018-05-01

The architecture of multi-layer imagers (MLIs) can be exploited to provide megavoltage spectral imaging (MVSPI) for specific imaging tasks. In the current work, we investigated bone suppression and gold fiducial contrast enhancement as two clinical tasks which could be improved with spectral imaging. A method based on analytical calculations that enables rapid investigation of MLI component materials and thicknesses was developed and validated against Monte Carlo computations. The figure of merit for task-specific imaging performance was the contrast-to-noise ratio (CNR) of the gold fiducial when the CNR of bone was equal to zero after a weighted subtraction of the signals obtained from each MLI layer. Results demonstrated a sharp increase in the CNR of gold when the build-up component or scintillation materials and thicknesses were modified. The potential for low-cost, prompt implementation of specific modifications (e.g. composition of the build-up component) could accelerate clinical translation of MVSPI.

Detection of delamination defects in CFRP materials using ultrasonic signal processing.

PubMed

Benammar, Abdessalem; Drai, Redouane; Guessoum, Abderrezak

2008-12-01

In this paper, signal processing techniques are tested for their ability to resolve echoes associated with delaminations in carbon fiber-reinforced polymer multi-layered composite materials (CFRP) detected by ultrasonic methods. These methods include split spectrum processing (SSP) and the expectation-maximization (EM) algorithm. A simulation study on defect detection was performed, and results were validated experimentally on CFRP with and without delamination defects taken from aircraft. Comparison of the methods for their ability to resolve echoes are made.

Numerical Analysis of Deflections of Multi-Layered Beams

NASA Astrophysics Data System (ADS)

Biliński, Tadeusz; Socha, Tomasz

2015-03-01

The paper concerns the rheological bending problem of wooden beams reinforced with embedded composite bars. A theoretical model of the behaviour of a multi-layered beam is presented. The component materials of this beam are described with equations for the linear viscoelastic five-parameter rheological model. Two numerical analysis methods for the long-term response of wood structures are presented. The first method has been developed with SCILAB software. The second one has been developed with the finite element calculation software ABAQUS and user subroutine UMAT. Laboratory investigations were conducted on sample beams of natural dimensions in order to validate the proposed theoretical model and verify numerical simulations. Good agreement between experimental measurements and numerical results is observed.

Multilayer Membranes of Glycosaminoglycans and Collagen I Biomaterials Modulate the Function and Microvesicle Release of Endothelial Progenitor Cells.

PubMed

Dai, Bingyan; Pan, Qunwen; Li, Zhanghua; Zhao, Mingyan; Liao, Xiaorong; Wu, Keng; Ma, Xiaotang

2016-01-01

Multilayer composite membrane of biomaterials can increase the function of adipose stem cells or osteoprogenitor cells. Recent evidence indicates endothelial progenitor cells (EPCs) and EPCs released microvesicles (MVs) play important roles in angiogenesis and vascular repair. Here, we investigated the effects of biomaterial multilayer membranes of hyaluronic acid (HA) or chondroitin sulfate (CS) and Collagen I (Col I) on the functions and MVs release of EPCs. Layer-by-layer (LBL) technology was applied to construct the multilayer composite membranes. Four types of the membranes constructed by adsorbing either HA or CS and Col I alternatively with different top layers were studied. The results showed that all four types of multilayer composite membranes could promote EPCs proliferation and migration and inhibit cell senility, apoptosis, and the expression of activated caspase-3. Interestingly, these biomaterials increased the release and the miR-126 level of EPCs-MVs. Moreover, the CS-Col I membrane with CS on the top layer showed the most effects on promoting EPCs proliferation, EPCs-MV release, and miR-126 level in EPCs-MVs. In conclusion, HA/CS and Collagen I composed multilayer composite membranes can promote EPCs functions and release of miR-126 riched EPCs-MVs, which provides a novel strategy for tissue repair treatment.

Chitosan/alginate multilayer film for controlled release of IDM on Cu/LDPE composite intrauterine devices.

PubMed

Tian, Kuan; Xie, Changsheng; Xia, Xianping

2013-09-01

To reduce such side effects as pain and bleeding caused by copper-containing intrauterine device (Cu-IUD), a novel medicated intrauterine device, which is coated with an indomethacin (IDM) delivery system on the surface of copper/low-density polyethylene (Cu/LDPE) composite intrauterine device, has been proposed and developed in the present work. The IDM delivery system is a polyelectrolyte multilayer film, which is composed of IDM containing chitosan and alginate layer by layer, is prepared by using self-assembled polyelectrolyte multilayer method, and the number of the layers of this IDM containing chitosan/alginate multilayer film can be tailored by controlling the cyclic repetition of the deposition process. After the IDM containing chitosan/alginate multilayer film is obtained on the surface of Cu/LDPE composite intrauterine device, its release behavior of both IDM and cupric ion has been studied in vitro. The results show that the release duration of IDM increase with the increasing of thickness of the IDM containing chitosan/alginate multilayer film, and the initial burst release of cupric ion cannot be found in this novel medicated Cu/LDPE composite IUD. These results can be applied to guide the design of novel medicated Cu-IUD with minimal side effects for the future clinical use. Copyright © 2013 Elsevier B.V. All rights reserved.

Tunable structural color in organisms and photonic materials for design of bioinspired materials

NASA Astrophysics Data System (ADS)

Fudouzi, Hiroshi

2011-12-01

In this paper, the key topics of tunable structural color in biology and material science are overviewed. Color in biology is considered for selected groups of tropical fish, octopus, squid and beetle. It is caused by nanoplates in iridophores and varies with their spacing, tilting angle and refractive index. These examples may provide valuable hints for the bioinspired design of photonic materials. 1D multilayer films and 3D colloidal crystals with tunable structural color are overviewed from the viewpoint of advanced materials. The tunability of structural color by swelling and strain is demonstrated on an example of opal composites.

Tunable structural color in organisms and photonic materials for design of bioinspired materials

PubMed Central

Fudouzi, Hiroshi

2011-01-01

In this paper, the key topics of tunable structural color in biology and material science are overviewed. Color in biology is considered for selected groups of tropical fish, octopus, squid and beetle. It is caused by nanoplates in iridophores and varies with their spacing, tilting angle and refractive index. These examples may provide valuable hints for the bioinspired design of photonic materials. 1D multilayer films and 3D colloidal crystals with tunable structural color are overviewed from the viewpoint of advanced materials. The tunability of structural color by swelling and strain is demonstrated on an example of opal composites. PMID:27877454

Application of an Instrumental and Computational Approach for Improving the Vibration Behavior of Structural Panels Using a Lightweight Multilayer Composite

PubMed Central

Sánchez, Alberto; García, Manuel; Sebastián, Miguel Angel; Camacho, Ana María

2014-01-01

This work presents a hybrid (experimental-computational) application for improving the vibration behavior of structural components using a lightweight multilayer composite. The vibration behavior of a flat steel plate has been improved by the gluing of a lightweight composite formed by a core of polyurethane foam and two paper mats placed on its faces. This composite enables the natural frequencies to be increased and the modal density of the plate to be reduced, moving about the natural frequencies of the plate out of excitation range, thereby improving the vibration behavior of the plate. A specific experimental model for measuring the Operating Deflection Shape (ODS) has been developed, which enables an evaluation of the goodness of the natural frequencies obtained with the computational model simulated by the finite element method (FEM). The model of composite + flat steel plate determined by FEM was used to conduct parametric study, and the most influential factors for 1st, 2nd and 3rd mode were identified using a multifactor analysis of variance (Multifactor-ANOVA). The presented results can be easily particularized for other cases, as it may be used in cycles of continuous improvement as well as in the product development at the material, piece, and complete-system levels. PMID:24618779

Process-Parameter-Dependent Optical and Structural Properties of ZrO2MgO Mixed-Composite Films Evaporated from the solid Solution

NASA Technical Reports Server (NTRS)

Sahoo, N. K.; Shapiro, A. P.

1998-01-01

The process-parameter-dependent optical and structural properties of ZrO2MgO mixed-composite material have been investigated. Optical properties were derived from spectrophotometric measurements. By use of atomic force microscopy, x-ray diffraction analysis, and energy-dispersive x-ray (EDX) analysis, the surface morphology, grain size distributions, crystallographic phases, and process-dependent material composition of films have been investigated. EDX analysis made evident the correlation between the oxygen enrichment in the films prepared at a high level of oxygen pressure and the very low refractive index. Since oxygen pressure can be dynamically varied during a deposition process, coatings constructed of suitable mixed-composite thin films can benefit from continuous modulation of the index of refraction. A step modulation approach is used to develop various multilayer-equivalent thin-film devices.

In-situ stress measurement of single and multilayer thin-films used in x-ray astronomy optics applications

NASA Astrophysics Data System (ADS)

Broadway, David M.; Ramsey, Brian D.; O'Dell, Stephen L.; Gurgew, Danielle

2017-09-01

We present in-situ stress measurement results for single and multilayer thin-films deposited by magnetron sputtering. In particular, we report on the influence of the material interfaces on the ensuing stress in both the transient and steady-state regimes of film growth. This behavior is used to determine the appropriate thicknesses of the constituent layers that will result in a net tensile stress in multilayers composed of various material combinations. These multilayers can then be used to compensate the compressive integrated stress in single and multilayer EUV and x-ray optical coatings. The use of multilayers to compensate the integrated stress might be advantageous because, unlike single layers of chromium, the roughness is not expected to increase with the total thickness of the multilayer. In this paper, we demonstrate the technique for W/Si and Mo/Si multilayers and discuss its application to other material combinations.

An experimental study on laser drilling and cutting of composite materials for the aerospace industry using excimer and CO2 sources

NASA Astrophysics Data System (ADS)

dell'Erba, M.; Galantucci, L. M.; Miglietta, S.

This paper reports on the results of research which investigated the potential for the application of an excimer laser in the field of composite material drilling and cutting, by comparing this technology with that using CO2 sources. In particular, the scope of the work was to check whether the interaction between excimer lasers and composite materials, whose characteristic feature is the absence of thermal transfer, could yield better results than those obtainable with CO2 sources once heat transfer-induced difficulties had been eliminated. The materials selected for the experiments were multilayer composites having an epoxy resin matrix (65 percent in volume), with aramid fiber (Kevlar), carbon fiber and glass fiber as reinforcing materials, all of considerable interest for the aerospace industry. Optimal operational parameters were identified in relation to each source with a view to obtaining undersize holes or through cuts exhibiting severed areas of good quality. A comparison between the two types of processing carried out show that rims processed by excimer lasers are of better quality - particularly so with Kevlar - whereas the ablation rate is undoubtedly rather low compared with the CO2 technology.

Artificial multilayers and nanomagnetic materials.

PubMed

Shinjo, Teruya

2013-01-01

The author has been actively engaged in research on nanomagnetic materials for about 50 years. Nanomagnetic materials are comprised of ferromagnetic systems for which the size and shape are controlled on a nanometer scale. Typical examples are ultrafine particles, ultrathin films, multilayered films and nano-patterned films. In this article, the following four areas of the author's studies are described.(1) Mössbauer spectroscopic studies of nanomagnetic materials and interface magnetism.(2) Preparation and characterization of metallic multilayers with artificial superstructures.(3) Giant magnetoresistance (GMR) effect in magnetic multilayers.(4) Novel properties of nanostructured ferromagnetic thin films (dots and wires).A subject of particular interest in the author's research was the artificially prepared multilayers consisting of metallic elements. The motivation to initiate the multilayer investigation is described and the physical properties observed in the artificial multilayers are introduced. The author's research was initially in the field of pure physical science and gradually extended into applied science. His achievements are highly regarded not only from the fundamental point of view but also from the technological viewpoint.

Cryogenic Vacuum Insulation for Vessels and Piping

NASA Technical Reports Server (NTRS)

Kogan, A.; Fesmire, J.; Johnson, W.; Minnick, J.

2010-01-01

Cryogenic vacuum insulation systems, with proper materials selection and execution, can offer the highest levels of thermal performance. Three areas of consideration are vital to achieve the optimum result: materials, representative test conditions, and engineering approach for the particular application. Deficiency in one of these three areas can prevent optimum performance and lead to severe inefficiency. Materials of interest include micro-fiberglass, multilayer insulation, and composite arrangements. Cylindrical liquid nitrogen boil-off calorimetry methods were used. The need for standard thermal conductivity data is addressed through baseline testing. Engineering analysis and design factors such as layer thickness, density, and practicality are also considered.

Experimental correlation between nonlinear optical and magnetotransport properties observed in Au-Co thin films

DOE PAGES

Yang, Kaida; Kryutyanskiy, Victor; Kolmychek, Irina; ...

2016-01-01

Magnetic materials where at least one dimension is in the nanometer scale typically exhibit different magnetic, magnetotransport, and magnetooptical properties compared to bulk materials. Composite magnetic thin films where the matrix composition, magnetic cluster size, and overall composite film thickness can be experimentally tailored via adequate processing or growth parameters offer a viable nanoscale platform to investigate possible correlations between nonlinear magnetooptical and magnetotransport properties, since both types of properties are sensitive to the local magnetization landscape. As a result, it has been shown that the local magnetization contrast affects the nonlinear magnetooptical properties as well as the magnetotransport propertiesmore » in magnetic-metal/nonmagnetic metal multilayers; thus, nanocomposite films showcase another path to investigate possible correlations between these distinct properties which may prove useful for sensing applications.« less

Integrated Composite Analyzer (ICAN): Users and programmers manual

NASA Technical Reports Server (NTRS)

Murthy, P. L. N.; Chamis, C. C.

1986-01-01

The use of and relevant equations programmed in a computer code designed to carry out a comprehensive linear analysis of multilayered fiber composites is described. The analysis contains the essential features required to effectively design structural components made from fiber composites. The inputs to the code are constituent material properties, factors reflecting the fabrication process, and composite geometry. The code performs micromechanics, macromechanics, and laminate analysis, including the hygrothermal response of fiber composites. The code outputs are the various ply and composite properties, composite structural response, and composite stress analysis results with details on failure. The code is in Fortran IV and can be used efficiently as a package in complex structural analysis programs. The input-output format is described extensively through the use of a sample problem. The program listing is also included. The code manual consists of two parts.

Mechanical Behavior of Fabric-Film Laminates

NASA Technical Reports Server (NTRS)

Said, Magdi S.

1999-01-01

Inflatable structures are gaining wide support in planetary scientific missions as well as commercial applications. For such applications a new class of materials made of laminating thin homogenous films to lightweight fabrics are being considered us structura1 gas envelops. The emerging composite materials are a result of recent advances in the manufacturing cf 1ightweight, high strength fibers, fabrics and scrims. The lamination of these load-carrying members with the proper gas barrier film results in wide range of materials suitable for various loading and environmental conditions. Polyester - based woven fabrics laminated to thin homogeneus film of polyester (Maylar) is an example of this class. This fabric/ film laminate is being considered for the development a material suitable for building large gas envelopes for use in the NASA Ultra Long Duration Balloon Program (ULDB). Compared to commercial homogeneus films, the material provides relatively high strength to weight ratio as well as better resistance to crack and tear propagation. The purpose of this papers is to introduce the mechanical behavior of this class of multi-layers composite and to highlight some of the concerns observed during the characterization of these laminate composites.

Comparison of InGaAs(100) Grown by Chemical Beam Epitaxy and Metal Organic Chemical Vapor Deposition

NASA Technical Reports Server (NTRS)

Williams, M. D.; Greene, A. L.; Daniels-Race, T.; Lum, R. M.

2000-01-01

Secondary ion mass spectrometry is used to study the effects of substrate temperature on the composition and growth rate of InGaAs/InP(100) multilayers grown by chemical beam epitaxy, metal-organic chemical vapor deposition and solid source molecular beam epitaxy. The growth kinetics of the material grown by the different techniques are analyzed and compared.

Sputter-Coated Microparticle Additives for Tailored Optical Properties

DTIC Science & Technology

2016-09-01

hour at best). The microspheres coated in this work will be incorporated into a polymer matrix for composite and large-area coating applications...demonstrated, they will be incorporated into a polymer matrix for further testing. 15. SUBJECT TERMS fluidized bed, thin film, microparticles, coating...films of metals, ceramics , and multilayered materials.1 This is a practical method for the batch production of microparticles with tailored optical

Improving the tribological and corrosive properties of MoS2-based coatings by dual-doping and multilayer construction

NASA Astrophysics Data System (ADS)

Shang, Kedong; Zheng, Shaoxian; Ren, Siming; Pu, Jibin; He, Dongqing; Liu, Shuan

2018-04-01

The pure MoS2 coating always performs high friction coefficient and short service life when used in high humidity or after long-time storage in humid atmospheric environment. In this study, the MoS2/Pb-Ti composite and MoS2/Pb-Ti multilayer coatings are deposited to improve the corrosion resistance in 3.5 wt% NaCl solution and tribological performance in high humidity condition. The electrochemical impedance spectra and salt spray test shown that the MoS2/Pb-Ti composite and multilayer coatings can inhibit the permeation of oxygen and other corrosive elements, thus resulting a high corrosion resistance. Furthermore, compared with pure MoS2 coating, the tribological performance of the MoS2/Pb-Ti composite and multilayer coatings is also improved significantly owing to the high mechanical properties and compact structure. Moreover, the heterogenous interfaces in MoS2/Pb-Ti multilayer coating play an important role to improve the corrosion resistance and tribological performance of coatings. Overall, the dual-doping and multilayer construction are promising approaches to design the MoS2 coatings as the environmentally adaptive lubricants.

The Energetics of Oxide Multilayer Systems: SOFC Cathode and Electrolyte Materials

NASA Astrophysics Data System (ADS)

Kemik, Nihan

Complex oxides are evoking a surge of scientific and technological interest due to the unexpected properties of their interfaces which have been shown to differ from the constituent materials. Layered oxide structures have found wide use in applications ranging from electronic and magnetic devices to solid oxide fuel cells (SOFCs). For devices such as SOFCs which utilize multilayers at elevated temperatures, it is critical to know the relative stabilities of these interfaces since they directly influence the device performance. In this work, we explored the energetics of two oxide multilayer systems which are relevant for SOFCs components using high temperature solution calorimetry and differential scanning calorimetry (DSC). The fundamental understanding of the interfacial and structural properties of multilayers combined with the information about phase stabilities is essential in materials selection for components for intermediate temperature SOFC's. For cathode materials, we investigated the family of perovskite oxides, La0.7Sr0.3MO3, where M=Mn and Fe, as well as their solid solution phase. Manganites have been the most investigated cathode material, while the ferrites are also being considered for future use due to their thermodynamic stability and close thermal expansion coefficient with the commonly used electrolyte materials. For the bulk La0.7Sr0.3FexMn1-xO 3 solid solution, high temperature oxide melt drop solution calorimetry was performed to determine the enthalpies of formation from binary oxides and the enthalpy of mixing. It was shown that the symmetry of the perovskite structure, the valence of transition metal, and the energetics are highly interdependent and the balance between the different valence states of the Mn and Fe ions is the main factor in determining the energetics. The energetics of interfaces in multilayered structures was investigated by high temperature oxide melt solution calorimetry for the first time. The drop solution calorimetry results of La0.7Sr0.3MnO3(LSMO)/La0.7 Sr0.3FeO3(LSFO) multilayers and LSMO film are highly exothermic and differ from the bulk material with the same composition. The magnetic and electronic properties of LSMO/LSFO superlattices are highly dependent on the thickness and the structure of the individual layers. Resonant X-Ray reflectivity (XRR) technique was utilized to characterize the structure of the LSMO/LSFO superlattices. It was shown that the XRR spectra taken at the Mn and Fe absorption edges can provide more structural information than the spectra at the X-ray energy of a conventional Cu source. With this non-destructive technique, we demonstrated the ability to compare the intermixing behavior and thickness regularity throughout the thickness of different superlattice structures. For electrolyte materials, we studied the yttria stabilized zirconia (YSZ) /Al2O3 multilayer system. Differential scanning calorimetry (DSC) was used to study the crystallization of the YSZ layers to explore the effect of the interfaces on phase stabilities. It was observed that the crystallization temperature increased and the enthalpy became more exothermic as the interfacial area increased. This work demonstrated that DSC is a promising technique to study the thin film reactions and explore the interfacial enthalpies in oxide multilayer systems.

Characterization of the dimensional stability of advanced metallic materials using an optical test bench structure

NASA Technical Reports Server (NTRS)

Hsieh, Cheng; O'Donnell, Timothy P.

1991-01-01

The dimensional stability of low-density high specific-strength metal-matrix composites (including 30 vol pct SiC(p)/SXA 24-T6 Al, 25 vol pct SiC(p)/6061-T6 Al, 40 vol pct graphite P100 fiber/6061 Al, 50 vol pct graphite P100 fiber/6061 Al, and 40 vol pct P100 graphite fiber/AZ91D Mg composites) and an Al-Li-Mg metal alloy was evaluated using a specially designed five-strut optical test bench structure. The structure had 30 thermocouple locations, one retroreflector, one linear interferometer multilayer insulation, and various strip heaters. It was placed in a 10 exp -7 torr capability vacuum chamber with a laser head positioned at a window port, and a laser interferometer system for collecting dimensional change data. It was found that composite materials have greater 40-C temporal dimensional stability than the AL-Li-Mg alloy. Aluminum-based composites demonstrated better 40-C temporal stability than Mg-based composites.

Review: mechanical behavior of metal/ceramic interfaces in nanolayered composites—experiments and modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Nan; Liu, Xiang-Yang

In this study, recent experimental and modeling studies in nanolayered metal/ceramic composites are reviewed, with focus on the mechanical behaviors of metal/nitrides interfaces. The experimental and modeling studies of the slip systems in bulk TiN are reviewed first. Then, the experimental studies of interfaces, including co-deformation mechanism by micropillar compression tests, in situ TEM straining tests for the dynamic process of the co-deformation, thickness-dependent fracture behavior, and interrelationship among the interfacial bonding, microstructure, and mechanical response, are reviewed for the specific material systems of Al/TiN and Cu/TiN multilayers at nanoscale. The modeling studies reviewed cover first-principles density functional theory-based modeling,more » atomistic molecular dynamics simulations, and mesoscale modeling of nanolayered composites using discrete dislocation dynamics. The phase transformation between zinc-blende and wurtzite AlN phases in Al/AlN multilayers at nanoscale is also reviewed. Finally, a summary and perspective of possible research directions and challenges are given.« less

Review: mechanical behavior of metal/ceramic interfaces in nanolayered composites—experiments and modeling

DOE PAGES

Li, Nan; Liu, Xiang-Yang

2017-11-03

In this study, recent experimental and modeling studies in nanolayered metal/ceramic composites are reviewed, with focus on the mechanical behaviors of metal/nitrides interfaces. The experimental and modeling studies of the slip systems in bulk TiN are reviewed first. Then, the experimental studies of interfaces, including co-deformation mechanism by micropillar compression tests, in situ TEM straining tests for the dynamic process of the co-deformation, thickness-dependent fracture behavior, and interrelationship among the interfacial bonding, microstructure, and mechanical response, are reviewed for the specific material systems of Al/TiN and Cu/TiN multilayers at nanoscale. The modeling studies reviewed cover first-principles density functional theory-based modeling,more » atomistic molecular dynamics simulations, and mesoscale modeling of nanolayered composites using discrete dislocation dynamics. The phase transformation between zinc-blende and wurtzite AlN phases in Al/AlN multilayers at nanoscale is also reviewed. Finally, a summary and perspective of possible research directions and challenges are given.« less

Biomolecular hybrid material and process for preparing same and uses for same

DOEpatents

Kim, Jungbae [Richland, WA

2010-11-23

Disclosed is a composition and method for fabricating novel hybrid materials comprised of, e.g., carbon nanotubes (CNTs) and crosslinked enzyme clusters (CECs). In one method, enzyme-CNT hybrids are prepared by precipitation of enzymes which are subsequently crosslinked, yielding crosslinked enzyme clusters (CECs) on the surface of the CNTs. The CEC-enzyme-CNT hybrids exhibit high activity per unit area or mass as well as improved enzyme stability and longevity over hybrid materials known in the art. The CECs in the disclosed materials permit multilayer biocatalytic coatings to be applied to surfaces providing hybrid materials suitable for use in, e.g., biocatalytic applications and devices as described herein.

Development of Flexible Multilayer Circuits and Cables

NASA Technical Reports Server (NTRS)

Barnes, Kevin N.; Bryant, Robert; Holloway, Nancy; Draughon, Fred

2005-01-01

A continuing program addresses the development of flexible multilayer electronic circuits and associated flexible cables. This development is undertaken to help satisfy aerospace-system-engineering requirements for efficient, lightweight electrical and electronic subsystems that can fit within confined spaces, adhere to complexly shaped surfaces, and can be embedded within composite materials. Heretofore, substrate layers for commercial flexible circuitry have been made from sheets of Kapton (or equivalent) polyimide and have been bonded to copper conductors and to other substrate layers by means of adhesives. The substrates for the present developmental flexible circuitry are made from thin films of a polyimide known as LaRC(TM)-SI. This polyimide is thermoplastic and, therefore, offers the potential to eliminate delamination and the need for adhesives. The development work undertaken thus far includes experiments in the use of several techniques of design and fabrication (including computer-aided design and fabrication) of representative flexible circuits. Anticipated future efforts would focus on multilayer bonding, fabrication of prototypes, and overcoming limitations.

Artificial multilayers and nanomagnetic materials

PubMed Central

SHINJO, Teruya

2013-01-01

The author has been actively engaged in research on nanomagnetic materials for about 50 years. Nanomagnetic materials are comprised of ferromagnetic systems for which the size and shape are controlled on a nanometer scale. Typical examples are ultrafine particles, ultrathin films, multilayered films and nano-patterned films. In this article, the following four areas of the author’s studies are described. (1) Mössbauer spectroscopic studies of nanomagnetic materials and interface magnetism. (2) Preparation and characterization of metallic multilayers with artificial superstructures. (3) Giant magnetoresistance (GMR) effect in magnetic multilayers. (4) Novel properties of nanostructured ferromagnetic thin films (dots and wires). A subject of particular interest in the author’s research was the artificially prepared multilayers consisting of metallic elements. The motivation to initiate the multilayer investigation is described and the physical properties observed in the artificial multilayers are introduced. The author’s research was initially in the field of pure physical science and gradually extended into applied science. His achievements are highly regarded not only from the fundamental point of view but also from the technological viewpoint. PMID:23391605

Boosting the power performance of multilayer graphene as lithium-ion battery anode via unconventional doping with in-situ formed Fe nanoparticles

PubMed Central

Raccichini, Rinaldo; Varzi, Alberto; Chakravadhanula, Venkata Sai Kiran; Kübel, Christian; Passerini, Stefano

2016-01-01

Graphene is extensively investigated and promoted as a viable replacement for graphite, the state-of-the-art material for lithium-ion battery (LIB) anodes, although no clear evidence is available about improvements in terms of cycling stability, delithiation voltage and volumetric capacity. Here we report the microwave-assisted synthesis of a novel graphene-based material in ionic liquid (i.e., carved multilayer graphene with nested Fe3O4 nanoparticles), together with its extensive characterization via several physical and chemical techniques. When such a composite material is used as LIB anode, the carved paths traced by the Fe3O4 nanoparticles, and the unconverted metallic iron formed in-situ upon the 1st lithiation, result in enhanced rate capability and, especially at high specific currents (i.e., 5 A g−1), remarkable cycling stability (99% of specific capacity retention after 180 cycles), low average delithiation voltage (0.244 V) and a substantially increased volumetric capacity with respect to commercial graphite (58.8 Ah L−1 vs. 9.6 Ah L−1). PMID:27026069

Nanoscale Engineering of Efficient Oxygen Reduction Electrocatalysts by Tailoring the Local Chemical Environment of Pt Surface Sites

DOE PAGES

Cleve, Tim Van; Moniri, Saman; Belok, Gabrielle; ...

2016-11-16

The oxygen reduction reaction is the limiting half-reaction in hydrogen fuel cells. While Pt is the most active single component electrocatalyst for the reaction, it is hampered by high cost and low reaction rates. Most research to overcome these limitations has focused on Pt/3d alloys, which offer higher rates and lower cost. Here, we have synthesized, characterized, and tested alloy materials belonging to a multilayer family of electrocatalysts. The multilayer alloy materials contain an AuCu alloy core of precise composition, surrounded by Au layers and covered by a catalytically active Pt surface layer. Their performance relative to that of themore » commercial Pt standards reaches up to 4 times improved area-specific activity. Characterization studies support the hypothesis that the activity improvement originates from a combination of Au–Pt ligand effects and local strain effects manipulated through the AuCu alloy core. The approach we present to control the strain and ligand effects in the synthesis of Pt-based alloys for the ORR is very general and could lead to promising alloy materials.« less

Release-rate calorimetry of multilayered materials for aircraft seats

NASA Technical Reports Server (NTRS)

Fewell, L. L.; Duskin, F. E.; Spieth, H.; Trabold, E.; Parker, J. A.

1979-01-01

Multilayered samples of contemporary and improved fire resistant aircraft seat materials (foam cushion, decorative fabric, slip sheet, fire blocking layer, and cushion reinforcement layer) were evaluated for their rates of heat release and smoke generation. Top layers (decorative fabric, slip sheet, fire blocking, and cushion reinforcement) with glass fiber block cushion were evaluated to determine which materials based on their minimum contributions to the total heat release of the multilayered assembly may be added or deleted. Top layers exhibiting desirable burning profiles were combined with foam cushion materials. The smoke and heat release rates of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/sq cm. Choices of contact and silicone adhesives for bonding multilayered assemblies were based on flammability, burn and smoke generation, animal toxicity tests, and thermal gravimetric analysis. Abrasion tests were conducted on the decorative fabric covering and slip sheet to ascertain service life and compatibility of layers.

Dual-Use Applications of Infrared Sensitive Materials

DTIC Science & Technology

1993-06-01

only limit to MCT-based detectors’ market potential is in price. Specialty systems for subsurface imaging (such as buried storage tanks, toxic wastes...and assessment of automotive paint damaged by rust or stone impacts. Since automotive paint is a multi-layered coating, it lends itself to subsurface ... imaging , as well as aerospace aluminum and epoxy composites. Another family of non-destructive evaluation techniques which could use infrared detectors

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

Development of extreme ultraviolet and soft x-ray multilayer optics for scientific studies with femtosecond/attosecond sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aquila, Andrew Lee

The development of multilayer optics for extreme ultraviolet (EUV) radiation has led to advancements in many areas of science and technology, including materials studies, EUV lithography, water window microscopy, plasma imaging, and orbiting solar physics imaging. Recent developments in femtosecond and attosecond EUV pulse generation from sources such as high harmonic generation lasers, combined with the elemental and chemical specificity provided by EUV radiation, are opening new opportunities to study fundamental dynamic processes in materials. Critical to these efforts is the design and fabrication of multilayer optics to transport, focus, shape and image these ultra-fast pulses This thesis describes themore » design, fabrication, characterization, and application of multilayer optics for EUV femtosecond and attosecond scientific studies. Multilayer mirrors for bandwidth control, pulse shaping and compression, tri-material multilayers, and multilayers for polarization control are described. Characterization of multilayer optics, including measurement of material optical constants, reflectivity of multilayer mirrors, and metrology of reflected phases of the multilayer, which is critical to maintaining pulse size and shape, were performed. Two applications of these multilayer mirrors are detailed in the thesis. In the first application, broad bandwidth multilayers were used to characterize and measure sub-100 attosecond pulses from a high harmonic generation source and was performed in collaboration with the Max-Planck institute for Quantum Optics and Ludwig- Maximilians University in Garching, Germany, with Professors Krausz and Kleineberg. In the second application, multilayer mirrors with polarization control are useful to study femtosecond spin dynamics in an ongoing collaboration with the T-REX group of Professor Parmigiani at Elettra in Trieste, Italy. As new ultrafast x-ray sources become available, for example free electron lasers, the multilayer designs described in this thesis can be extended to higher photon energies, and such designs can be used with those sources to enable new scientific studies, such as molecular bonding, phonon, and spin dynamics.« less

Parametric study using modal analysis of a bi-material plate with defects

NASA Astrophysics Data System (ADS)

Esola, S.; Bartoli, I.; Horner, S. E.; Zheng, J. Q.; Kontsos, A.

2015-03-01

Global vibrational method feasibility as a non-destructive inspection tool for multi-layered composites is evaluated using a simulated parametric study approach. A finite element model of a composite consisting of two, isotropic layers of dissimilar materials and a third, thin isotropic layer of adhesive is constructed as the representative test subject. Next, artificial damage is inserted according to systematic variations of the defect morphology parameters. A free-vibrational modal analysis simulation is executed for pristine and damaged plate conditions. Finally, resultant mode shapes and natural frequencies are extracted, compared and analyzed for trends. Though other defect types may be explored, the focus of this research is on interfacial delamination and its effects on the global, free-vibrational behavior of a composite plate. This study is part of a multi-year research effort conducted for the U.S. Army Program Executive Office - Soldier.

Nanolaminated FeCoB/FeCo and FeCoB/NiFe soft magnetic thin films with tailored magnetic properties deposited by magnetron sputtering

NASA Astrophysics Data System (ADS)

Hida, Rachid; Falub, Claudiu V.; Perraudeau, Sandrine; Morin, Christine; Favier, Sylvie; Mazel, Yann; Saghi, Zineb; Michel, Jean-Philippe

2018-05-01

Thin films based on layers of Fe52Co28B20 (at%), Fe65Co35 (at%), and Ni80Fe20 (at%) were deposited by sputtering on 8″ bare Si and Si/200 nm-thermal-SiO2 wafers by simultaneous use of two or more cathodes. Due to the continuous rotation of the substrate cage, such that the substrates faced different targets alternately, the multilayers consisted of stacks of alternating, nanometer-thick regular layers. The composition of the films was determined by Rutherford Backscattering Spectrometry (RBS) and Nuclear Reactive Analysis (NRA), whereas Plasma Profiling Time of Flight Mass Spectrometry (PP-TOFMS) analysis gave depth profile information about the chemical elements. The structural and magnetic properties of the films were investigated by X-ray Diffraction and by TEM analysis, B-H loop tracer and high frequency single coil technique permeametry, respectively. The linear dependence of the coercivity of these thin films versus the grain size can be explained by the random anisotropy model. These novel, composite soft magnetic multilayers, with tunable in-plane anisotropy, allow operation at tunable frequencies, as shown by broadband (between 100 MHz and 10 GHz) RF measurements that exhibit a classical Landau-Lifschitz-Gilbert (LLG) behavior and, combine the magnetic properties of the individual materials in an advantageous way. This article presents a method to produce nanostructured soft magnetic multilayers, the properties of which can easily be tuned by choosing the ratio of the individual nanolayers. In this way it's possible to combine soft magnetic materials with complementary properties, e.g. high saturation magnetization, low coercivity, high specific resistivity and low magnetostriction

Environmentally Benign Stab Detonators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gash, A

2005-12-21

Many energetic systems can be activated via mechanical means. Percussion primers in small caliber ammunition and stab detonators used in medium caliber ammunition are just two examples. Current medium caliber (20-60mm) munitions are detonated through the use of impact sensitive stab detonators. Stab detonators are very sensitive and must be small, as to meet weight and size limitations. A mix of energetic powders, sensitive to mechanical stimulus, is typically used to ignite such devices. Stab detonators are mechanically activated by forcing a firing pin through the closure disc of the device and into the stab initiating mix. Rapid heating causedmore » by mechanically driven compression and friction of the mixture results in its ignition. The rapid decomposition of these materials generates a pressure/temperature pulse that is sufficient to initiate a transfer charge, which has enough output energy to detonate the main charge. This general type of ignition mix is used in a large variety of primers, igniters, and detonators.[1] Common primer mixes, such as NOL-130, are made up of lead styphnate (basic) 40%, lead azide (dextrinated) 20%, barium nitrate 20%, antimony sulfide 15%, and tetrazene 5%.[1] These materials pose acute and chronic toxicity hazards during mixing of the composition and later in the item life cycle after the item has been field functioned. There is an established need to replace these mixes on toxicity, health, and environmental hazard grounds. This effort attempts to demonstrate that environmentally acceptable energetic solgel coated flash metal multilayer nanocomposites can be used to replace current impact initiated devices (IIDs), which have hazardous and toxic components. Successful completion of this project will result in IIDs that include innocuous compounds, have sufficient output energy for initiation, meet current military specifications, are small, cost competitive, and perform as well as or better than current devices. We expect flash metal multilayer and sol-gel to be generic technologies applicable to a wide range of devices, especially in small caliber ammunition and sub-munitions. We will replace the NOL-130 mixture with a nanocomposite that consists of a mechanically robust energetic multilayer foil that has been coated with a sol-gel energetic material. The exothermic reactions are activated in this nanocomposite are the transformation of the multilayer material to its respective intermetallic alloy and the thermite reaction, which is characterized by very high temperatures, a small pressure pulse, and hot particle ejection. The proposed materials and their reaction products consist of, but are not limited to aluminum, nickel, iron, aluminum oxide, titanium, iron oxide and boron. These materials have much more desirable environmental and health characteristics than the NOL-130 composition.« less

Influence of surface topography on RBS measurements: case studies of (Cu/Fe/Pd) multilayers and FePdCu alloys nanopatterned by self-assembly

NASA Astrophysics Data System (ADS)

Krupinski, M.; Perzanowski, M.; Zabila, Y.; Zarzycki, A.; Marszałek, M.

2017-03-01

In this paper the influence of surface topography on Rutherford backscattering spectrometry (RBS) is discussed. (Cu/Fe/Pd) multilayers with total thickness of about 10 nm were deposited by physical vapor deposition on self-organized array of SiO2 nanoparticles with the size of 50 nm and 100 nm. As a reference, the multilayered systems were also prepared on flat substrates under the same conditions. After the deposition, morphology of the systems was studied by scanning electron microscopy (SEM), while chemical analysis was performed using Rutherford backscattering spectrometry. It was found that the RBS spectra and determined compositions for flat and patterned multilayers differ. The difference is discussed by taking into account the effect of additional inelastic scattering and energy straggling occurring due to developed topography of patterned systems. Then, the multilayers were annealed in 600 °C in order to obtain FePdCu alloy. The phenomenon of solid-state dewetting resulted in the formation of isolated alloy islands on the top of SiO2 nanoparticles. The SEM and RBS analysis were repeated showing correlation between the size distribution of obtained alloy islands and broadening of peaks appearing in RBS spectra. Invited talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8-12 November 2016, Ha Long City, Vietnam.

Etched-multilayer phase shifting masks for EUV lithography

DOEpatents

Chapman, Henry N.; Taylor, John S.

2005-04-05

A method is disclosed for the implementation of phase shifting masks for EUV lithography. The method involves directly etching material away from the multilayer coating of the mask, to cause a refractive phase shift in the mask. By etching into the multilayer (for example, by reactive ion etching), rather than depositing extra material on the top of the multilayer, there will be minimal absorption loss associated with the phase shift.

Controlled synthesis of MnOOH multilayer nanowires as anode materials for lithium-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Yue; Yue, Kaiqiang; Wang, Yuanxin

MnOOH multilayer nanowires have been successfully synthesized by a hydrothermal method. It is found that the uniform multilayer structure of nanowires ran through the entire nanowire, which is formed via a layer by layer. The electrochemical properties of MnOOH multilayer nanowires as an anode material for Li-ion batteries (LIB) were investigated, and excellent capacity retention, superior cycling performance, and high rate capability were achieved. Specifically, the reversible capacity of MnOOH multilayer nanowires is 521 mAh/g after 500 cycles at 0.1 C, with excellent electrochemical stability. The multilayer nanowire electrodes exhibit short electron path lengths, high internal dislocation densities and largemore » surface to volume ratio, resulting in increased specific capacity, cycling stability and rate performance in the energy storage devices, which serves as an indication of their potential application in LIBs. - Highlights: •MnOOH multilayer nanowires were synthesized by a hydrothermal method. •The uniform multilayer structure of nanowires was formed via layer by layer. •The reversible capacity of product shows 521 mAh/g after 500 cycles at 0.1 C. •MnOOH multilayer nanowires showed higher property as anode material in LIB.« less

Biomineralized poly (l-lactic-co-glycolic acid)-tussah silk fibroin nanofiber fabric with hierarchical architecture as a scaffold for bone tissue engineering.

PubMed

Gao, Yanfei; Shao, Weili; Qian, Wang; He, Jianxin; Zhou, Yuman; Qi, Kun; Wang, Lidan; Cui, Shizhong; Wang, Rui

2018-03-01

In bone tissue engineering, the fabrication of a scaffold with a hierarchical architecture, excellent mechanical properties, and good biocompatibility remains a challenge. Here, a solution of polylactic acid (PLA) and Tussah silk fibroin (TSF) was electrospun into nanofiber yarns and woven into multilayer fabrics. Then, composite scaffolds were obtained by mineralization in simulated body fluid (SBF) using the multilayer fabrics as a template. The structure and related properties of the composite scaffolds were characterized using different techniques. PLA/TSF (mass ratio, 9:1) nanofiber yarns with uniform diameters of 72±9μm were obtained by conjugated electrospinning; the presence of 10wt% TSF accelerated the nucleation and growth of hydroxyapatite on the surface of the composite scaffolds in SBF. Furthermore, the compressive mechanical properties of the PLA/TSF multilayer nanofiber fabrics were improved after mineralization; the compressive modulus and stress of the mineralized composite scaffolds were 32.8 and 3.0 times higher than that of the composite scaffolds without mineralization, respectively. Interestingly, these values were higher than those of scaffolds containing random nanofibers. Biological assay results showed that the mineralization and multilayer fabric structure of the composite nanofiber scaffolds significantly increased cell adhesion and proliferation and enhanced the mesenchymal stem cell differentiation toward osteoblasts. Our results indicated that the mineralized nanofiber scaffolds with multilayer fabrics possessed excellent cytocompatibility and good osteogenic activity, making them versatile biocompatible scaffolds for bone tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

Numerical modeling of mechanical behavior of multilayered composite plates with defects under static loading

NASA Astrophysics Data System (ADS)

Korepanov, V. V.; Serovaev, G. S.

2017-06-01

Evaluation of the mechanical state of a structure or its components in the process of operation based on detection of internal damages (damage detection) becomes especially important in such rapidly developing spheres of production as machine building, aerospace industry, etc. One of the most important features of these industries is the application of new types of materials among which polymer based composite materials occupy a significant position. Hence, they must have sufficient operational rigidity and strength. However, defects of various kinds may arise during the manufacture. Delamination is the most common defect in structures made from composite materials and represents a phenomenon that involves the complex fracture of layers and interlayer compounds. Among the reasons of delamination occurrence are: disposition of anti-adhesive lubricants, films; insufficient content of binder, high content of volatile elements; violation of the molding regime; poor quality of anti-adhesive coating on the surface of the tooling. One of the effective methods for analyzing the influence of defects is numerical simulation. With the help of numerical methods, it is possible to track the evolution of various parameters when the defect size and quantity change. In the paper, a multilayered plate of an equally resistant carbon fiber reinforced plastic was considered, with a thickness of each layer equal to 0.2 mm. Various static loading cases are studied: uniaxial tension, three and four-point bending. For each type of loading, a numerical calculation of the stress-strain state was performed for healthy and delaminated plates, with different number and size of the defects. Contact interaction between adjacent surfaces in the zone of delamination was taken into account.

Self-assembled Li 3V 2(PO 4) 3/reduced graphene oxide multilayer composite prepared by sequential adsorption

DOE PAGES

Kim, Myeong-Seong; Bak, Seong-Min; Lee, Suk-Woo; ...

2017-09-26

Here in this paper, we report on Li 3V 2(PO 4) 3 (LVP)/reduced graphene oxide (rGO) multilayer composites prepared via a sequential adsorption method and subsequent heat treatment, and their use as cathodes for high-rate lithium-ion batteries. The sequential adsorption process includes adsorbing oppositely charged components of anionic inorganic species and cationic head of a surfactant adsorbed to graphite oxide sheets, which is a key step in the fabrication of the LVP/rGO multilayer composites. The multilayer structure has open channels between the highly conductive rGO layers while achieving a relatively high tap density, which could effectively improve the rate capability.more » Consequently, the LVP/rGO multilayer composites exhibit a high tap density (0.6 g cm -3) and good electrochemical properties. Specifically, in the voltage range of 3.0–4.3 V, the composite exhibits a specific capacity of 131 mAh g -1 at 0.1C, a good rate capabilities (88% capacity retention at 60C), and long cycling performance (97% capacity retention after 500 cycles at 10C). Moreover, in the extended voltage range of 3.0–4.8 V, it exhibits a high specific capacity of 185 mAh g -1 at 0.2C, a good rate capability (66% capacity retention at 30C), and stable cycling performance (96% capacity retention after 500 cycles at 10C).« less

Self-assembled Li 3V 2(PO 4) 3/reduced graphene oxide multilayer composite prepared by sequential adsorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Myeong-Seong; Bak, Seong-Min; Lee, Suk-Woo

Here in this paper, we report on Li 3V 2(PO 4) 3 (LVP)/reduced graphene oxide (rGO) multilayer composites prepared via a sequential adsorption method and subsequent heat treatment, and their use as cathodes for high-rate lithium-ion batteries. The sequential adsorption process includes adsorbing oppositely charged components of anionic inorganic species and cationic head of a surfactant adsorbed to graphite oxide sheets, which is a key step in the fabrication of the LVP/rGO multilayer composites. The multilayer structure has open channels between the highly conductive rGO layers while achieving a relatively high tap density, which could effectively improve the rate capability.more » Consequently, the LVP/rGO multilayer composites exhibit a high tap density (0.6 g cm -3) and good electrochemical properties. Specifically, in the voltage range of 3.0–4.3 V, the composite exhibits a specific capacity of 131 mAh g -1 at 0.1C, a good rate capabilities (88% capacity retention at 60C), and long cycling performance (97% capacity retention after 500 cycles at 10C). Moreover, in the extended voltage range of 3.0–4.8 V, it exhibits a high specific capacity of 185 mAh g -1 at 0.2C, a good rate capability (66% capacity retention at 30C), and stable cycling performance (96% capacity retention after 500 cycles at 10C).« less

N-enriched multilayered porous carbon derived from natural casings for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Zongying; Li, Yu; Li, Dandan; Wang, Dawei; Zhao, Jing; Wang, Zhifeng; Banis, Mohammad N.; Hu, Yongfeng; Zhang, Huaihao

2018-06-01

In this study, N-enriched multilayered porous activated carbon (LPAC), using natural casings as precursor, was fabricated by a facile carbonization and subsequent KOH activation procedure. The influence of the mass ratio of KOH to carbonized material on pore-structure and surface element composition of LPACs was investigated by a variety of means, such as SEM, HRTEM, BET, Raman, XRD, XPS and XAS. Owing to the unique multilayered texture and nitrogen (N) and oxygen (O) rich feature of natural casings, the resulting LPACs possess interconnected and developed porous structure with N- and O-enriched functional groups, contributing to larger pseudocapacitance. With the rise of mass ratio, the specific surface area (SSA) and average pore size of LPACs increased. The final materials were endowed with a desirable SSA (3100 m2 g-1) and high N content (6.34 at.%). Meanwhile, N- and O-enriched LPAC-4 exhibited a high specific capacitance (307.5 F g-1 at a current density of 0.5 A g-1 in 6 M KOH aqueous solution), excellent rate performance (63.4% capacitance retention at 20 A g-1) and good cycling stability (7.1% capacitance loss after 5000 cycles). Furthermore, the assembled symmetrical supercapacitor (LPAC-4//LPAC-4) with a wide voltage window of 1.4 V delivered a remarkable energy density of 11.6 Wh kg-1 at a power density of 297 W kg-1. These results suggested that unique LPACs derived from natural casings are a promising material for supercapacitors.

Conductive, magnetic and structural properties of multilayer films

NASA Astrophysics Data System (ADS)

Kotov, L. N.; Turkov, V. K.; Vlasov, V. S.; Lasek, M. P.; Kalinin, Yu E.; Sitnikov, A. V.

2013-12-01

Composite-semiconductor and composite-dielectric multilayer films were obtained by the ion beam sputtering method in the argon and hydrogen atmospheres with compositions: {[(Co45-Fe45-Zr10)x(Al2O3)y]-[α-Si]}120, {[(Co45-Ta45-Nb10)x(SiO2)y]-[SiO2]}56, {[(Co45-Fe45-Zr10)x(Al2O3)y]-[α-Si:H]}120. The images of surface relief and distribution of the dc current on composite layer surface were obtained with using of atomic force microscopy (AFM). The dependencies of specific electric resistance, ferromagnetic resonance (FMR) fields and width of line on metal (magnetic) phase concentration x and nanolayers thickness of multilayer films were obtained. The characteristics of FMR depend on magnetic interaction among magnetic granules in the composite layers and between the layers. These characteristics depend on the thickness of composite and dielectric or semiconductor nanolayers. The dependences of electric microwave losses on the x and alternating field frequency were investigated.

Acoustic Emission and Damage Accumulation for Various Woven C/SiC Composites Tested in Tension at Room Temperature

NASA Technical Reports Server (NTRS)

Morscher, Gregory; Petko, Jeanne; Kiser, James D.

2002-01-01

Modal acoustic emission (AE) has proven to be an excellent technique to monitor damage accumulation in ceramic matrix composites. In this study, AE was used to monitor tensile load-unload-reload hysteresis tests for a variety of C fiber reinforced, Sic matrix composites. C/SiC composites were reinforced with T-300 and IM7 fibers, had C, multilayer, or pseudo-porous C interphases, and had chemical vapor infiltrated Sic or melt-infiltrated SiC matrices. All of the composites exhibited considerable AE during testing. The extent and nature of the AE activity will be analyzed and discussed in light of matrix cracking and the variety of composite constituents. It is hoped that understanding the nature of stress-dependent damage accumulation in these materials can be of use in life-modeling for these types of composites.

Acoustic Emission and Damage Accumulation for Various Woven C/SiC Composites Tested in Tension at Room Temperature

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Petko, Jeanne; Kiser, James D.; Gray, Hugh R. (Technical Monitor)

2002-01-01

Modal acoustic emission (AE) has proven to be an excellent technique to monitor damage accumulation in ceramic matrix composites. In this study, AE was used to monitor tensile load-unload-reload hysteresis tests for a variety of C fiber reinforced, SiC matrix composites. C/SiC composites were reinforced with T300 and IM7 fibers, had C, multilayer, or pseudo-porous C interphases, and had chemical vapor infiltrated SiC or melt-infiltrated SiC matrices. All of the composites exhibited considerable AE during testing. The extent and nature of the AE activity will be analyzed and discussed in light of matrix cracking and the variety of composite constituents. It is hoped that understanding the nature of stress dependent damage accumulation in these materials can be of use in life modeling for these types of composites.

Influence of binding material of PZT coating on microresonator's electrical and mechanical properties

NASA Astrophysics Data System (ADS)

Janusas, Giedrius; Guobiene, Asta; Palevicius, Arvydas; Brunius, Alfredas; Cekas, Elingas; Baltrusaitis, Valentinas; Sakalys, Rokas

2017-06-01

Microresonators are fundamental components integrated in hosts of MEMS applications: covering the automotive sector, the telecommunication industry, electronic equipment for surface/material characterization and motion sensing, and etc. The aim of this paper is to investigate the mechanical and electrical properties of PZT film fabricated with three binding materials: polyvinyl butyral (PVB), polymethyl methacrylate (PMMA) and polystyrene (PS) and to evaluate applicability in control of microresonators Q factor. Micro particles of PZT powder were mixed with 20% solution of PVB, PMMA and PS in benzyl alcohol. For investigation of mechanical and electrical properties multilayer cantilevers were made. Obtained PZT and polymer paste was screen printed on copper (thickness 40 μm) using polyester monofilament screen meshes (layer thickness 50 μm) and dried for 30 min at 100°C. Electric dipoles of the PZT particles in composite material were aligned using high voltage generator (5 kV) and a custom-made holder. Electric field was held for 30 min. Surfaces of the applied films were investigated by Atomic Force Microscope NanoWizard(R)3 NanoScience. Dynamic and electrical characteristics of the multilayer were investigated using laser triangular displacement sensor LK-G3000. The measured vibration amplitude and generated electrical potential was collected with USB oscilloscope PicoScope 3424. As the results showed, these cantilevers were able to transform mechanical strain energy into electric potential and, v.v. However, roughness of PZT coatings with PMMA and PS were higher, what could be the reason of the worse quality of the top electrode. However, the main advantage of the created composite piezoelectric material is the possibility to apply it on any uniform or non-uniform vibrating surface and to transform low frequency vibrations into electricity.

Multilayer multiferroic composites with imperfect interfaces

NASA Astrophysics Data System (ADS)

Kuo, Hsin-Yi; Wu, Tien-Jung; Pan, Ernian

2018-07-01

We study the macroscopic behaviors of multilayered multiferroic composites with interface imperfections by a direct micromechanical approach. Both generalized interface stress type and generalized linear spring type imperfect interfaces are considered. Concise matrix expressions of the overall behaviors of the layered piezoelectric–piezomagnetic composite with contact imperfection are presented. The key step is to observe that the two types of imperfect interface conditions are equivalent to the perfect ones due to the laminated geometry. Numerical calculations are demonstrated for BaTiO3–CoFe2O4 multilayer media, and are shown in good agreement with the more involved interphase model. Furthermore, it is observed that the interface imperfection would reduce the magnitude of the magnetoelectric voltage coefficients as compared to the corresponding perfect interface case. This feature is opposite to that predicted and observed in the corresponding cylindrical composites.

Delamination Analysis Of Composite Curved Bars

NASA Technical Reports Server (NTRS)

Ko, William L.; Jackson, Raymond H.

1990-01-01

Classical anisotropic elasticity theory used to construct "multilayer" composite semicircular curved bar subjected to end forces and end moments. Radial location and intensity of open-mode delamination stress calculated and compared with results obtained from anisotropic continuum theory and from finite element method. Multilayer theory gave more accurate predictions of location and intensity of open-mode delamination stress. Currently being applied to predict open-mode delamination stress concentrations in horse-shoe-shaped composite test coupons.

Recent advances in the fabrication and structure-specific applications of graphene-based inorganic hybrid membranes.

PubMed

Zhao, Xinne; Zhang, Panpan; Chen, Yuting; Su, Zhiqiang; Wei, Gang

2015-03-12

The preparation and applications of graphene (G)-based materials are attracting increasing interests due to their unique electronic, optical, magnetic, thermal, and mechanical properties. Compared to G-based hybrid and composite materials, G-based inorganic hybrid membrane (GIHM) offers enormous advantages ascribed to their facile synthesis, planar two-dimensional multilayer structure, high specific surface area, and mechanical stability, as well as their unique optical and mechanical properties. In this review, we report the recent advances in the technical fabrication and structure-specific applications of GIHMs with desirable thickness and compositions. In addition, the advantages and disadvantages of the methods utilized for creating GIHMs are discussed in detail. Finally, the potential applications and key challenges of GIHMs for future technical applications are mentioned.

Method to adjust multilayer film stress induced deformation of optics

DOEpatents

Spiller, Eberhard A.; Mirkarimi, Paul B.; Montcalm, Claude; Bajt, Sasa; Folta, James A.

2000-01-01

Stress compensating systems that reduces/compensates stress in a multilayer without loss in reflectivity, while reducing total film thickness compared to the earlier buffer-layer approach. The stress free multilayer systems contain multilayer systems with two different material combinations of opposite stress, where both systems give good reflectivity at the design wavelengths. The main advantage of the multilayer system design is that stress reduction does not require the deposition of any additional layers, as in the buffer layer approach. If the optical performance of the two systems at the design wavelength differ, the system with the poorer performance is deposited first, and then the system with better performance last, thus forming the top of the multilayer system. The components for the stress reducing layer are chosen among materials that have opposite stress to that of the preferred multilayer reflecting stack and simultaneously have optical constants that allow one to get good reflectivity at the design wavelength. For a wavelength of 13.4 nm, the wavelength presently used for extreme ultraviolet (EUV) lithography, Si and Be have practically the same optical constants, but the Mo/Si multilayer has opposite stress than the Mo/Be multilayer. Multilayer systems of these materials have practically identical reflectivity curves. For example, stress free multilayers can be formed on a substrate using Mo/Be multilayers in the bottom of the stack and Mo/Si multilayers at the top of the stack, with the switch-over point selected to obtain zero stress. In this multilayer system, the switch-over point is at about the half point of the total thickness of the stack, and for the Mo/Be--Mo/Si system, there may be 25 deposition periods Mo/Be to 20 deposition periods Mo/Si.

Analytic theory of alternate multilayer gratings operating in single-order regime.

PubMed

Yang, Xiaowei; Kozhevnikov, Igor V; Huang, Qiushi; Wang, Hongchang; Hand, Matthew; Sawhney, Kawal; Wang, Zhanshan

2017-07-10

Using the coupled wave approach (CWA), we introduce the analytical theory for alternate multilayer grating (AMG) operating in the single-order regime, in which only one diffraction order is excited. Differing from previous study analogizing AMG to crystals, we conclude that symmetrical structure, or equal thickness of the two multilayer materials, is not the optimal design for AMG and may result in significant reduction in diffraction efficiency. The peculiarities of AMG compared with other multilayer gratings are analyzed. An influence of multilayer structure materials on diffraction efficiency is considered. The validity conditions of analytical theory are also discussed.

Innovative soft magnetic multilayers with enhanced in-plane anisotropy and ferromagnetic resonance frequency for integrated RF passive devices

NASA Astrophysics Data System (ADS)

Falub, Claudiu V.; Bless, Martin; Hida, Rachid; MeduÅa, Mojmír; Ammann, Arnold

2018-04-01

We present an innovative, economical method for manufacturing soft magnetic materials that may pave the way for integrated thin film magnetic cores with dramatically improved properties. Soft magnetic multilayered thin films based on the Fe-28%Co20%B (at.%) and Co-4.5%Ta4%Zr (at.%) amorphous alloys are deposited on 8" bare Si and Si/200nm-thermal-SiO2 wafers in an industrial, high-throughput Evatec LLS EVO II magnetron sputtering system. The multilayers consist of stacks of alternating 80-nm-thick ferromagnetic layers and 4-nm-thick Al2O3 dielectric interlayers. Since in our dynamic sputter system the substrate cage rotates continuously, such that the substrates face different targets alternatively, each ferromagnetic sublayer in the multilayer consists of a fine structure comprising alternating CoTaZr and FeCoB nanolayers with very sharp interfaces. We adjust the thickness of these individual nanolayers between 0.5 and 1.5 nm by changing the cage rotation speed and the power of each gun, which is an excellent mode to engineer new, composite ferromagnetic materials. Using X-ray reflectometry (XRR) we reveal that the interfaces between the FeCoB and CoTaZr nanolayers are perfectly smooth with roughness of 0.2-0.3 nm. Kerr magnetometry and B-H looper measurements for the as-deposited samples show that the coercivity of these thin films is very low, 0.2-0.3 Oe, and gradually scales up with the thickness of FeCoB nanolayers, i.e. with the increase of the overall Fe content from 0 % (e.g. CoTaZr-based multilayers) to 52 % (e.g. FeCoB-based multilayers). We explain this trend in the random anisotropy model, based on considerations of grain size growth, as revealed by glancing angle X-ray diffraction (GAXRD), but also because of the increase of magnetostriction with the increase of Fe content as shown by B-H looper measurements performed on strained wafers. The unexpected enhancement of the in-plane anisotropy field from 18.3 Oe and 25.8 Oe for the conventional CoTaZr- and FeCoB-based multilayers, respectively, up to ˜48 Oe for the nanostructured multilayers with FeCoB/CoTaZr nano-bilayers is explained based on interface anisotropy contribution. These novel soft magnetic multilayers, with enhanced in-plane anisotropy, allow operation at higher frequencies, as revealed by broadband (between 100 MHz and 10 GHz) RF measurements that exhibit a classical Landau-Lifschitz-Gilbert (LLG) behavior.

High temperature composite analyzer (HITCAN) user's manual, version 1.0

NASA Technical Reports Server (NTRS)

Lackney, J. J.; Singhal, S. N.; Murthy, P. L. N.; Gotsis, P.

1993-01-01

This manual describes 'how-to-use' the computer code, HITCAN (HIgh Temperature Composite ANalyzer). HITCAN is a general purpose computer program for predicting nonlinear global structural and local stress-strain response of arbitrarily oriented, multilayered high temperature metal matrix composite structures. This code combines composite mechanics and laminate theory with an internal data base for material properties of the constituents (matrix, fiber and interphase). The thermo-mechanical properties of the constituents are considered to be nonlinearly dependent on several parameters including temperature, stress and stress rate. The computation procedure for the analysis of the composite structures uses the finite element method. HITCAN is written in FORTRAN 77 computer language and at present has been configured and executed on the NASA Lewis Research Center CRAY XMP and YMP computers. This manual describes HlTCAN's capabilities and limitations followed by input/execution/output descriptions and example problems. The input is described in detail including (1) geometry modeling, (2) types of finite elements, (3) types of analysis, (4) material data, (5) types of loading, (6) boundary conditions, (7) output control, (8) program options, and (9) data bank.

AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 34th and AIAA/ASME Adaptive Structures Forum, La Jolla, CA, Apr. 19-22, 1993, Technical Papers. Pts. 1-6

NASA Astrophysics Data System (ADS)

Topics addressed include the prediction of helicopter component loads using neural networks, spacecraft on-orbit coupled loads analysis, hypersonic flutter of a curved shallow panel with aerodynamic heating, thermal-acoustic fatigue of ceramic matrix composite materials, transition elements based on transfinite interpolation, damage progression in stiffened composite panels, a direct treatment of min-max dynamic response optimization problems, and sources of helicopter rotor hub inplane shears. Also discussed are dynamics of a layered elastic system, confidence bounds on structural reliability, mixed triangular space-time finite elements, advanced transparency development for USAF aircraft, a low-velocity impact on a graphite/PEEK, an automated mode-tracking strategy, transonic flutter suppression by a passive flap, a nonlinear response of composite panels to random excitation, an optimal placement of elastic supports on a simply supported plate, a probabilistic assessment of composite structures, a model for mode I failure of laminated composites, a residual flexibility approach to multibody dynamics,and multilayer piezoelectric actuators.

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.

Preparation and Electrochemical Properties of Graphene/Epoxy Resin Composite Coating

NASA Astrophysics Data System (ADS)

Liao, Zijun; Zhang, Tianchi; Qiao, Sen; Zhang, Luyihang

2017-11-01

The multilayer graphene powder as filler, epoxy modified silicone resin as film-forming agent, anticorrosion composite coating has been created using sand dispersion method, the electrochemical performance was compared with different content of graphene composite coating and pure epoxy resin coating. The open circuit potential (OCP), potentiodynamic polarization curves (Tafel Plot) and electrochemical impedance spectroscopy (EIS) were tested. The test results showed that the anti-corrosion performance of multilayer graphene added has improved greatly, and the content of the 5% best corrosion performance of graphene composite coating.

Interfacial pattern changes of imprinted multilayered material in milli- and microscales

NASA Astrophysics Data System (ADS)

Yonekura, Kazuhiro; Tokumaru, Kazuki; Tsumori, Fujio

2018-06-01

Nanoimprint lithography (NIL) is a technique that transfers a mold pattern of nanometer order to the surface of a resist material by heating and pressing. NIL is an excellent technology in terms of high productivity, accuracy, and resolution. Recently, NIL has been applied to the processing of different multilayered materials, in which it is possible to process multiple materials simultaneously. In this processing of multilayered materials, it is possible to form an interfacial pattern between the upper layer and the lower layer simultaneously with patterning on the mold surface. This interface pattern can be controlled by the deformation characteristics, initial thickness, and so forth. In this research, we compared the interfacial pattern changes of imprinted multilayered materials in milli- and microscales. For multilayered imprint using multiple materials, it is important to know the flow of the resist and its dependence on the scale. If there is similarity in the relationship produced by the scale on the imprinted samples, a process design with a number of feedbacks could be realized. It also becomes easier to treat structures in the millimeter scale for the experiment. In this study, we employed micropowder imprint (µPI) for multilayered material imprint. A compound sheet of alumina powder and polymer binder was used for imprint. Two similar experiments in different scales, micro- and millimeter scales, were carried out. Results indicate that the interfacial patterns of micro- and millimeter-scale-imprinted samples are similar.

Crack Driving Forces in a Multilayered Coating System for Ceramic Matrix Composite Substrates

NASA Technical Reports Server (NTRS)

Ghosn, Louis J.; Zhu, Dongming; Miller, Robert A.

2005-01-01

The effects of the top coating thickness, modulus and shrinkage strains on the crack driving forces for a baseline multilayer Yttria-Stabilized-Zirconia/Mullite/Si thermal and environment barrier coating (TEBC) system for SiC/SiC ceramic matrix composite substrates are determined for gas turbine applications. The crack driving forces increase with increasing modulus, and a low modulus thermal barrier coating material (below 10 GPa) will have no cracking issues under the thermal gradient condition analyzed. Since top coating sintering increases the crack driving forces with time, highly sintering resistant coatings are desirable to maintain a low tensile modulus and maintain a low crack driving force with time. Finite element results demonstrated that an advanced TEBC system, such as ZrO2/HfO2, which possesses improved sintering resistance and high temperature stability, exhibited excellent durability. A multi-vertical cracked structure with fine columnar spacing is an ideal strain tolerant coating capable of reducing the crack driving forces to an acceptable level even with a high modulus of 50 GPa.

Progressive Failure And Life Prediction of Ceramic and Textile Composites

NASA Technical Reports Server (NTRS)

Xue, David Y.; Shi, Yucheng; Katikala, Madhu; Johnston, William M., Jr.; Card, Michael F.

1998-01-01

An engineering approach to predict the fatigue life and progressive failure of multilayered composite and textile laminates is presented. Analytical models which account for matrix cracking, statistical fiber failures and nonlinear stress-strain behavior have been developed for both composites and textiles. The analysis method is based on a combined micromechanics, fracture mechanics and failure statistics analysis. Experimentally derived empirical coefficients are used to account for the interface of fiber and matrix, fiber strength, and fiber-matrix stiffness reductions. Similar approaches were applied to textiles using Repeating Unit Cells. In composite fatigue analysis, Walker's equation is applied for matrix fatigue cracking and Heywood's formulation is used for fiber strength fatigue degradation. The analysis has been compared with experiment with good agreement. Comparisons were made with Graphite-Epoxy, C/SiC and Nicalon/CAS composite materials. For textile materials, comparisons were made with triaxial braided and plain weave materials under biaxial or uniaxial tension. Fatigue predictions were compared with test data obtained from plain weave C/SiC materials tested at AS&M. Computer codes were developed to perform the analysis. Composite Progressive Failure Analysis for Laminates is contained in the code CPFail. Micromechanics Analysis for Textile Composites is contained in the code MicroTex. Both codes were adapted to run as subroutines for the finite element code ABAQUS and CPFail-ABAQUS and MicroTex-ABAQUS. Graphic user interface (GUI) was developed to connect CPFail and MicroTex with ABAQUS.

Multiple wavelength photolithography for preparing multilayer microstructures

DOEpatents

Dentinger, Paul Michael; Krafcik, Karen Lee

2003-06-24

The invention relates to a multilayer microstructure and a method for preparing thereof. The method involves first applying a first photodefinable composition having a first exposure wavelength on a substrate to form a first polymeric layer. A portion of the first photodefinable composition is then exposed to electromagnetic radiation of the first exposure wavelength to form a first pattern in the first polymeric layer. After exposing the first polymeric layer, a second photodefinable composition having a second exposure wavelength is applied on the first polymeric layer to form a second polymeric layer. A portion of the second photodefinable composition is then exposed to electromagnetic radiation of the second exposure wavelength to form a second pattern in the second polymeric layer. In addition, a portion of each layer is removed according to the patterns to form a multilayer microstructure having a cavity having a shape that corresponds to the portions removed.

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.

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

Figure correction of multilayer coated optics

DOEpatents

Chapman; Henry N. , Taylor; John S.

2010-02-16

A process is provided for producing near-perfect optical surfaces, for EUV and soft-x-ray optics. The method involves polishing or otherwise figuring the multilayer coating that has been deposited on an optical substrate, in order to correct for errors in the figure of the substrate and coating. A method such as ion-beam milling is used to remove material from the multilayer coating by an amount that varies in a specified way across the substrate. The phase of the EUV light that is reflected from the multilayer will be affected by the amount of multilayer material removed, but this effect will be reduced by a factor of 1-n as compared with height variations of the substrate, where n is the average refractive index of the multilayer.

Electrostatic Surface Modifications to Improve Gene Delivery

PubMed Central

Shmueli, Ron B.; Anderson, Daniel G.

2010-01-01

Importance of the field Gene therapy has the potential to treat a wide variety of diseases including genetic diseases and cancer. Areas covered in this review This review introduces biomaterials used for gene delivery and then focuses on the use of electrostatic surface modifications to improve gene delivery materials. These modifications have been used to stabilize therapeutics in vivo, add cell-specific targeting ligands, and promote controlled release. Coatings of nanoparticles and microparticles as well as non-particulate surface coatings are covered in this review. Electrostatic principles are crucial for the development of multilayer delivery structures fabricated by the layer-by-layer method. What the reader will gain The reader will gain knowledge about the composition of biomaterials used for surface modifications and how these coatings and multilayers can be utilized to improve spatial control and efficiency of delivery. Examples are shown for the delivery of nucleic acids, including DNA and siRNA, to in vitro and in vivo systems. Take home message The versatile and powerful approach of electrostatic coatings and multilayers will lead to the development of enhanced gene therapies. PMID:20201712

ZrO2 Layer Thickness Dependent Electrical and Dielectric Properties of BST/ZrO2/BST Multilayer Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahoo, S. K.; Misra, D.; Agrawal, D. C.

2011-01-01

Recently, high K materials play an important role in microelectronic devices such as capacitors, memory devices, and microwave devices. Now a days ferroelectric barium strontium titanate [Ba{sub x}Sr{sub 1-x}TiO{sub 3}, (BST)] thin film is being actively investigated for applications in dynamic random access memories (DRAM), field effect transistor (FET), and tunable devices because of its properties such as high dielectric constant, low leakage current, low dielectric loss, and high dielectric breakdown strength. Several approaches have been used to optimize the dielectric and electrical properties of BST thin films such as doping, graded compositions, and multilayer structures. We have found thatmore » inserting a ZrO{sub 2} layer in between two BST layers results in a significant reduction in dielectric constant, loss tangent, and leakage current in the multilayer thin films. Also it is shown that the properties of multilayer structure are found to depend strongly on the sublayer thicknesses. In this work the effect of ZrO{sub 2} layer thickness on the dielectric, ferroelectric as well as electrical properties of BST/ZrO{sub 2}/BST multilayer structure is studied. The multilayer Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3}/ZrO{sub 2}/Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} film is deposited by a sol-gel process on the platinized Si substrate. The thickness of the middle ZrO{sub 2} layer is varied while keeping the top and bottom BST layer thickness as fixed. It is observed that the dielectric constant, dielectric loss tangent, and leakage current of the multilayer films reduce with the increase of ZrO{sub 2} layer thickness and hence suitable for memory device applications. The ferroelectric properties of the multilayer film also decrease with the ZrO{sub 2} layer thickness.« less

Improved irradiation tolerance of reactive gas pulse sputtered TiN coatings with a hybrid architecture of multilayered and compositionally graded structures

NASA Astrophysics Data System (ADS)

Liang, Wei; Yang, Jijun; Zhang, Feifei; Lu, Chenyang; Wang, Lumin; Liao, Jiali; Yang, Yuanyou; Liu, Ning

2018-04-01

This study investigates the improved irradiation tolerance of reactive gas pulse (RGP) sputtered TiN coatings which has hybrid architecture of multilayered and compositionally graded structures. The multilayered RGP-TiN coating is composed of hexagonal close-packed Ti phase and face-centred cubic TiN phase sublayers, where the former sublayer has a compositionally graded structure and the latter one maintains constant stoichiometric atomic ratio of Ti:N. After 100 keV He ion irradiation, the RGP-TiN coating exhibits improved irradiation resistance compared with its single layered (SL) counterpart. The size and density of He bubbles are smaller in the RGP-TiN coating than in the SL-TiN coating. The irradiation-induced surface blistering of the coatings shows a similar tendency. Meanwhile, the irradiation hardening and adhesion strength of the RGP-TiN coatings were not greatly affected by He irradiation. Moreover, the irradiation damage tolerance of the coatings can be well tuned by changing the undulation period number of N2 gas flow rate. Detailed analysis suggested that this improved irradiation tolerance could be related to the combined contribution of the multilayered and compositionally graded structures.

Microstructure and properties of aluminium-aluminium oxide graded composite materials

NASA Astrophysics Data System (ADS)

Kamaruzaman, F. F.; Nuruzzaman, D. M.; Ismail, N. M.; Hamedon, Z.; Iqbal, A. K. M. A.; Azhari, A.

2018-03-01

In this research works, four-layered aluminium-aluminium oxide (Al-Al2O3) graded composite materials were fabricated using powder metallurgy (PM) method. In processing, metal-ceramic graded composite materials of 0%, 10%, 20% and 30% weight percentage of ceramic concentration were prepared under 30 ton compaction load using a cylindrical die-punch set made of steel. After that, two-step pressureless sintering was carried out at sintering temperature and time 600°C and 3 hours respectively. It was observed that the sintered cylindrical specimens of 30 mm diameter were prepared successfully. The graded composite specimens were analysed and the properties such as density, microstructure and hardness were measured. It was found that after sintering process, the diameter of the graded cylindrical structure was decreased. Using both Archimedes method and rule of mixture (ROM), he density of structure was measured. The obtained results revealed that the microvickers hardness was increased as the ceramic component increases in the graded layer. Moreover, it was observed that the interface of the graded structure is clearly distinguished within the multilayer stack and the ceramic particles are almost uniformly distributed in the Al matrix.

A diffusion-limited reaction model for self-propagating Al/Pt multilayers with quench limits

NASA Astrophysics Data System (ADS)

Kittell, D. E.; Yarrington, C. D.; Hobbs, M. L.; Abere, M. J.; Adams, D. P.

2018-04-01

A diffusion-limited reaction model was calibrated for Al/Pt multilayers ignited on oxidized silicon, sapphire, and tungsten substrates, as well as for some Al/Pt multilayers ignited as free-standing foils. The model was implemented in a finite element analysis code and used to match experimental burn front velocity data collected from several years of testing at Sandia National Laboratories. Moreover, both the simulations and experiments reveal well-defined quench limits in the total Al + Pt layer (i.e., bilayer) thickness. At these limits, the heat generated from atomic diffusion is insufficient to support a self-propagating wave front on top of the substrates. Quench limits for reactive multilayers are seldom reported and are found to depend on the thermal properties of the individual layers. Here, the diffusion-limited reaction model is generalized to allow for temperature- and composition-dependent material properties, phase change, and anisotropic thermal conductivity. Utilizing this increase in model fidelity, excellent overall agreement is shown between the simulations and experimental results with a single calibrated parameter set. However, the burn front velocities of Al/Pt multilayers ignited on tungsten substrates are over-predicted. Possible sources of error are discussed and a higher activation energy (from 41.9 kJ/mol.at. to 47.5 kJ/mol.at.) is shown to bring the simulations into agreement with the velocity data observed on tungsten substrates. This higher activation energy suggests an inhibited diffusion mechanism present at lower heating rates.

75 FR 66126 - Multilayered Wood Flooring From China

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-27

...)] Multilayered Wood Flooring From China AGENCY: United States International Trade Commission. ACTION: Institution... the United States is materially retarded, by reason of imports from China of multilayered wood... multilayered wood flooring. The following companies are members of the CAHP: Anderson Hardwood Floors, LLC...

Multi-Scale Analyses of Three Dimensional Woven Composite 3D Shell With a Cut Out Circle

NASA Astrophysics Data System (ADS)

Nguyen, Duc Hai; Wang, Hu

2018-06-01

A composite material are made by combining two or more constituent materials to obtain the desired material properties of each product type. The matrix material which can be polymer and fiber is used as reinforcing material. Currently, the polymer matrix is widely used in many different fields with differently designed structures such as automotive structures and aviation, aerospace, marine, etc. because of their excellent mechanical properties; in addition, they possess the high level of hardness and durability together with a significant reduction in weight compared to traditional materials. However, during design process of structure, there will be many interruptions created for the purpose of assembling the structures together or for many other design purposes. Therefore, when this structure is subject to load-bearing, its failure occurs at these interruptions due to stress concentration. This paper proposes multi-scale modeling and optimization strategies in evaluation of the effectiveness of fiber orientation in an E-glass/Epoxy woven composite 3D shell with circular holes at the center investigated by FEA results. A multi-scale model approach was developed to predict the mechanical behavior of woven composite 3D shell with circular holes at the center with different designs of material and structural parameters. Based on the analysis result of laminae, we have found that the 3D shell with fiber direction of 450 shows the best stress and strain bearing capacity. Thus combining several layers of 450 fiber direction in a multi-layer composite 3D shell reduces the stresses concentrated on the cuts of the structures.

A multilayered supramolecular self-assembled structure from soybean oil by in situ polymerization and its applications.

PubMed

Kavitha, Varadharajan; Gnanamani, Arumugam

2013-05-01

The present study emphasizes in situ transformation of soybean oil to self-assembled supramolecular multilayered biopolymer material. The said polymer material was characterized and the entrapment efficacy of both hydrophilic and hydrophobic moieties was studied. In brief, soybean oil at varying concentration was mixed with mineral medium and incubated under agitation (200 rpm) at 37 degrees C for 240 h. Physical observations were made till 240 h and the transformed biopolymer was separated and subjected to physical, chemical and functional characterization. The maximum size of the polymer material was measured as 2 cm in diameter and the cross sectional view displayed the multilayered onion rings like structures. SEM analysis illustrated the presence of multilayered honeycomb channeled structures. Thermal analysis demonstrated the thermal stability (200 degrees C) and high heat enthalpy (1999 J/g). Further, this multilayered assembly was able to entrap both hydrophilic and hydrophobic components simultaneously, suggesting the potential industrial application of this material.

Piezoelectric Micro- and Nanostructured Fibers Fabricated from Thermoplastic Nanocomposites Using a Fiber Drawing Technique: Comparative Study and Potential Applications.

PubMed

Lu, Xin; Qu, Hang; Skorobogatiy, Maksim

2017-02-28

We report an all-polymer flexible piezoelectric fiber that uses both judiciously chosen geometry and advanced materials in order to enhance fiber piezoelectric response. The microstructured/nanostructured fiber features a soft hollow polycarbonate core surrounded by a spiral multilayer cladding consisting of alternating layers of piezoelectric nanocomposites (polyvinylidene enhanced with BaTiO 3 , PZT, or CNT) and conductive polymer (carbon-filled polyethylene). The conductive polymer layers serve as two electrodes, and they also form two spatially offset electric connectors on the fiber surface designed for the ease of connectorization. Kilometer-long piezoelectric fibers of sub-millimeter diameters are thermally drawn from a macroscopic preform. The fibers exhibit high output voltage of up to 6 V under moderate bending, and they show excellent mechanical and electrical durability in a cyclic bend-release test. The micron/nanosize multilayer structure enhances in-fiber poling efficiency due to the small distance between the conducting electrodes sandwiching the piezoelectric composite layers. Additionally, the spiral structure greatly increases the active area of the piezoelectric composite, thus promoting higher voltage generation and resulting in 10-100 higher power generation efficiency over the existing piezoelectric cables. Finally, we weave the fabricated piezoelectric fibers into technical textiles and demonstrate their potential applications in power generation when used as a sound detector, smart car seat upholstery, or wearable materials.

Shape and Stress Sensing of Multilayered Composite and Sandwich Structures Using an Inverse Finite Element Method

NASA Technical Reports Server (NTRS)

Cerracchio, Priscilla; Gherlone, Marco; Di Sciuva, Marco; Tessler, Alexander

2013-01-01

The marked increase in the use of composite and sandwich material systems in aerospace, civil, and marine structures leads to the need for integrated Structural Health Management systems. A key capability to enable such systems is the real-time reconstruction of structural deformations, stresses, and failure criteria that are inferred from in-situ, discrete-location strain measurements. This technology is commonly referred to as shape- and stress-sensing. Presented herein is a computationally efficient shape- and stress-sensing methodology that is ideally suited for applications to laminated composite and sandwich structures. The new approach employs the inverse Finite Element Method (iFEM) as a general framework and the Refined Zigzag Theory (RZT) as the underlying plate theory. A three-node inverse plate finite element is formulated. The element formulation enables robust and efficient modeling of plate structures instrumented with strain sensors that have arbitrary positions. The methodology leads to a set of linear algebraic equations that are solved efficiently for the unknown nodal displacements. These displacements are then used at the finite element level to compute full-field strains, stresses, and failure criteria that are in turn used to assess structural integrity. Numerical results for multilayered, highly heterogeneous laminates demonstrate the unique capability of this new formulation for shape- and stress-sensing.

High reflectance and low stress Mo2C/Be multilayers

DOEpatents

Bajt, Sasa; Barbee, Jr., Troy W.

2001-01-01

A material for extreme ultraviolet (EUV) multilayers that will reflect at about 11.3 nm, have a high reflectance, low stress, and high thermal and radiation stability. The material consists of alternating layers of Mo.sub.2 C and Be deposited by DC magnetron sputtering on a substrate, such as silicon. In one example a Mo.sub.2 C/Be multilayer gave 65.2% reflectance at 11.25 nm measured at 5 degrees off normal incidence angle, and consisted of 70 bilayers with a deposition period of 5.78 nm, and was deposited at 0.83 mTorr argon (Ar) sputtering pressure, with the first and last layers being Be. The stress of the multilayer is tensile and only +88 MPa, compared to +330 MPa of a Mo/Be multilayers of the same thickness. The Mo.sub.2 C/Be multilayer was capped with carbon which produced an increase in reflectivity of about 7% over a similar multilayer with no carbon capping material, thus raising the reflectivity from 58.3% to over 65%. The multilayers were formed using either Mo.sub.2 C or Be as the first and last layers, and initial testing has shown the formation of beryllium carbide at the interfaces between the layers which both stabilizes and has a smoothing effect, and appear to be smoother than the interfaces in Mo/Be multilayers.

The research Of Multilayer Thermal Insulation With Mechanical Properties Based On Model Analysis Test

NASA Astrophysics Data System (ADS)

Lianhua, Yin

The heat shield of aircraft is made of the major thrusts structure with multilayer thermal insulation part. For protecting against thermo-radiation from larger thrusting force engine,the heat shield is installed around this engine nearby.The multilayer thermal insulation part with multilayer radiation/reflection structure is made of reflection layer and interval layer.At vacuum condition,these materials is higher heat insulation capability than other material,is applied for lots of pats on aircraft extensively.But because of these material is made of metal and nonmetal,it is impossible to receive it's mechanical properties of materials from mechanical tests.These paper describes a new measure of mechanical properties of materials in the heat shield based on model analysis test.At the requirement for the first order lateral frequency,these measure provide for the FEM analysis foundation on the optimization structure of the heat shield.

Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride carbide and carbonitride

DOEpatents

Wong, M.S.; Li, D.; Chung, Y.W.; Sproul, W.D.; Xi Chu; Barnett, S.A.

1998-03-10

A composite material having high hardness comprises a carbon nitrogen compound, such as CN{sub x} where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN{sub x}. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45--55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating. 10 figs.

Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride, carbide and carbonitride

DOEpatents

Wong, M.S.; Li, D.; Chung, Y.W.; Sproul, W.D.; Chu, X.; Barnett, S.A.

1998-07-07

A composite material having high hardness comprises a carbon nitrogen compound, such as CN{sub x} where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN{sub x}. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45--55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating. 10 figs.

Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride, carbide and carbonitride

DOEpatents

Wong, Ming-Show; Li, Dong; Chung, Yip-Wah; Sproul, William D.; Chu, Xi; Barnett, Scott A.

1998-01-01

A composite material having high hardness comprises a carbon nitrogen compound, such as CN.sub.x where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN.sub.x. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45-55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating.

Superhard composite materials including compounds of carbon and nitrogen deposited on metal and metal nitride carbide and carbonitride

DOEpatents

Wong, Ming-Show; Li, Dong; Chung, Yin-Wah; Sproul, William D.; Chu, Xi; Barnett, Scott A.

1998-01-01

A composite material having high hardness comprises a carbon nitrogen compound, such as CN.sub.x where x is greater than 0.1 and up to 1.33, deposited on a metal or metal compound selected to promote deposition of substantially crystalline CN.sub.x. The carbon nitrogen compound is deposited on a crystal plane of the metal or metal compound sufficiently lattice-matched with a crystal plane of the carbon nitrogen compound that the carbon nitrogen compound is substantially crystalline. A plurality of layers of the compounds can be formed in alternating sequence to provide a multi-layered, superlattice coating having a coating hardness in the range of 45-55 GPa, which corresponds to the hardness of a BN coating and approaches that of a diamond coating.

Pyrolysis Model Development for a Multilayer Floor Covering

PubMed Central

McKinnon, Mark B.; Stoliarov, Stanislav I.

2015-01-01

Comprehensive pyrolysis models that are integral to computational fire codes have improved significantly over the past decade as the demand for improved predictive capabilities has increased. High fidelity pyrolysis models may improve the design of engineered materials for better fire response, the design of the built environment, and may be used in forensic investigations of fire events. A major limitation to widespread use of comprehensive pyrolysis models is the large number of parameters required to fully define a material and the lack of effective methodologies for measurement of these parameters, especially for complex materials. The work presented here details a methodology used to characterize the pyrolysis of a low-pile carpet tile, an engineered composite material that is common in commercial and institutional occupancies. The studied material includes three distinct layers of varying composition and physical structure. The methodology utilized a comprehensive pyrolysis model (ThermaKin) to conduct inverse analyses on data collected through several experimental techniques. Each layer of the composite was individually parameterized to identify its contribution to the overall response of the composite. The set of properties measured to define the carpet composite were validated against mass loss rate curves collected at conditions outside the range of calibration conditions to demonstrate the predictive capabilities of the model. The mean error between the predicted curve and the mean experimental mass loss rate curve was calculated as approximately 20% on average for heat fluxes ranging from 30 to 70 kW·m−2, which is within the mean experimental uncertainty. PMID:28793556

Ablative Laser Propulsion Using Multi-Layered Material Systems

NASA Technical Reports Server (NTRS)

Nehls, Mary; Edwards, David; Gray, Perry; Schneider, T.

2002-01-01

Experimental investigations are ongoing to study the force imparted to materials when subjected to laser ablation. When a laser pulse of sufficient energy density impacts a material, a small amount of the material is ablated. A torsion balance is used to measure the momentum produced by the ablation process. The balance consists of a thin metal wire with a rotating pendulum suspended in the middle. The wire is fixed at both ends. Recently, multi-layered material systems were investigated. These multi-layered materials were composed of a transparent front surface and opaque sub surface. The laser pulse penetrates the transparent outer surface with minimum photon loss and vaporizes the underlying opaque layer.

Optimisation of Fabric Reinforced Polymer Composites Using a Variant of Genetic Algorithm

NASA Astrophysics Data System (ADS)

Axinte, Andrei; Taranu, Nicolae; Bejan, Liliana; Hudisteanu, Iuliana

2017-12-01

Fabric reinforced polymeric composites are high performance materials with a rather complex fabric geometry. Therefore, modelling this type of material is a cumbersome task, especially when an efficient use is targeted. One of the most important issue of its design process is the optimisation of the individual laminae and of the laminated structure as a whole. In order to do that, a parametric model of the material has been defined, emphasising the many geometric variables needed to be correlated in the complex process of optimisation. The input parameters involved in this work, include: widths or heights of the tows and the laminate stacking sequence, which are discrete variables, while the gaps between adjacent tows and the height of the neat matrix are continuous variables. This work is one of the first attempts of using a Genetic Algorithm ( GA) to optimise the geometrical parameters of satin reinforced multi-layer composites. Given the mixed type of the input parameters involved, an original software called SOMGA (Satin Optimisation with a Modified Genetic Algorithm) has been conceived and utilised in this work. The main goal is to find the best possible solution to the problem of designing a composite material which is able to withstand to a given set of external, in-plane, loads. The optimisation process has been performed using a fitness function which can analyse and compare mechanical behaviour of different fabric reinforced composites, the results being correlated with the ultimate strains, which demonstrate the efficiency of the composite structure.

Exposure to space radiation of high-performance infrared multilayer filters and materials technology experiment (A0056)

NASA Technical Reports Server (NTRS)

Hawkins, Gary J.; Seeley, John S.; Hunneman, Roger

1992-01-01

Infrared optical multilayer filters and materials were exposed to the space environment of low Earth orbit on LDEF. The effects are summarized of that environment on the physical and optical properties of the filters and materials flown.

Axial postbuckling analysis of multilayer functionally graded composite nanoplates reinforced with GPLs based on nonlocal strain gradient theory

NASA Astrophysics Data System (ADS)

Sahmani, S.; Aghdam, M. M.

2017-11-01

In this paper, a new size-dependent inhomogeneous plate model is constructed to analyze the nonlinear buckling and postbuckling characteristics of multilayer functionally graded composite nanoplates reinforced with graphene platelet (GPL) nanofillers under axial compressive load. To this purpose, the nonlocal strain gradient theory of elasticity is implemented into a refined hyperbolic shear deformation plate theory. The mechanical properties of multilayer graphene platelet-reinforced composite (GPLRC) nanoplates are evaluated based upon the Halpin-Tsai micromechanical scheme. The weight fraction of randomly dispersed GPLs remain constant in each individual layer, which results in U-GPLRC nanoplate, or changes layerwise in accordance with three different functionally graded patterns, which make X-GPLRC, O-GPLRC and A-GPLRC nanoplates. Via a two-stepped perturbation technique, explicit analytical expressions for nonlocal strain gradient stability paths are established for layerwise functionally graded GPLRC nanoplates. It is demonstrated that both the nonlocal and strain gradient size dependencies are more significant for multilayer GPLRC nanoplates filling by GPL nanofillers with higher length-to-thickness and width-to-thickness ratios.

Effect of stacking sequence and surface treatment on the thermal conductivity of multilayered hybrid nano-composites

NASA Astrophysics Data System (ADS)

Papanicolaou, G. C.; Pappa, E. J.; Portan, D. V.; Kotrotsos, A.; Kollia, E.

2018-02-01

The aim of the present investigation was to study the effect of both the stacking sequence and surface treatment on the thermal conductivity of multilayered hybrid nano-composites. Four types of multilayered hybrid nanocomposites were manufactured and tested: Nitinol- CNTs (carbon nanotubes)- Acrylic resin; Nitinol- Acrylic resin- CNTs; Surface treated Nitinol- CNTs- Acrylic resin and Surface treated Nitinol- Acrylic resin- CNTs. Surface treatment of Nitinol plies was realized by means of the electrochemical anodization. Surface topography of the anodized nitinol sheets was investigated through Scanning Electron Microscopy (SEM). It was found that the overall thermal response of the manufactured multilayered nano-composites was greatly influenced by both the anodization and the stacking sequence. A theoretical model for the prediction of the overall thermal conductivity has been developed considering the nature of the different layers, their stacking sequence as well as the interfacial thermal resistance. Thermal conductivity and Differential Scanning Calorimetry (DSC) measurements were conducted, to verify the predicted by the model overall thermal conductivities. In all cases, a good agreement between theoretical predictions and experimental results was found.

High Dose Neutron Irradiation of Hi-Nicalon Type S Silicon Carbide Composites, Part 2. Mechanical and Physical Properties

DOE PAGES

Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao Phillip; ...

2015-01-07

Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573–1073 K. Likewise, the material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating themore » irradiation temperature, but only to a limited extent. Moreover, the observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.« less

Migration of plasticizers from poly(vinyl chloride) and multilayer infusion bags using selective extraction and GC-MS.

PubMed

Haned, Zohra; Moulay, Saad; Lacorte, Silvia

2018-04-12

Flexible poly(vinyl chloride) (PVC) is widely used in the pharmaceutical industry for the manufacture of medical devices (tubes, probes, bags, primary packaging, etc.). The objective of the present study was to develop a procedure to evaluate the migration potential of nine plastic additives in aqueous infusion bags (NaCl 0.9% and glucose 5%): five phthalates, one adipate, two alkylphenols, and benzophenone. Two types of materials were analyzed: (i) new and outdated plasticized PVC (containing 40% of diethylhexyl phthalate DEHP); and (ii) tri-laminate polyethylene-polyamide-polypropylene, a multilayer material presumably exempt from DEHP. In addition, we evaluated the migration of plasticizers from PVC raw materials (film and grain) under controlled conditions to compare the migration levels according to Regulation 2011/10. Solid phase extraction and liquid-liquid extraction with gas-chromatography coupled to mass spectrometry were used in all tests. The migration of DEHP in PVC grain exceeded the maximum regulated level of 5000 μg/kg, whereas the levels were much lower in films. In new PVC bags, DEHP was the only compound detected at 4.31 ± 0.5 μg/L in NaCl 0.9% and 4.29 ± 0.25 μg/L in glucose 5% serums, whereas the levels increased 10 times in three-year shelf-life bags. In multilayer bags, DEHP was not found but instead, two plasticizers were detected namely dibuthylphthalate (DBP) and diethylphthalate (DEP) at 0.7 ± 0.1 μg/L and 4.14 ± 0.6 μg/L, respectively. These plasticizers are not mentioned as additives allowed in materials intended for parenteral use (European Pharmacopoeia 8.0, 3.1.5. and 3.1.6.). Caprolactam was tentatively identified and could have stemmed from the polyamide of the multilayer composite. The levels of phthalates remained low but not negligible and might constitute a risk to public health in the case of reiterative infusions. Copyright © 2018. Published by Elsevier B.V.

Analysis of buried interfaces in multilayer mirrors using grazing incidence extreme ultraviolet reflectometry near resonance edges.

PubMed

Sertsu, M G; Nardello, M; Giglia, A; Corso, A J; Maurizio, C; Juschkin, L; Nicolosi, P

2015-12-10

Accurate measurements of optical properties of multilayer (ML) mirrors and chemical compositions of interdiffusion layers are particularly challenging to date. In this work, an innovative and nondestructive experimental characterization method for multilayers is discussed. The method is based on extreme ultraviolet (EUV) reflectivity measurements performed on a wide grazing incidence angular range at an energy near the absorption resonance edge of low-Z elements in the ML components. This experimental method combined with the underlying physical phenomenon of abrupt changes of optical constants near EUV resonance edges enables us to characterize optical and structural properties of multilayers with high sensitivity. A major advantage of the method is to perform detailed quantitative analysis of buried interfaces of multilayer structures in a nondestructive and nonimaging setup. Coatings of Si/Mo multilayers on a Si substrate with period d=16.4  nm, number of bilayers N=25, and different capping structures are investigated. Stoichiometric compositions of Si-on-Mo and Mo-on-Si interface diffusion layers are derived. Effects of surface oxidation reactions and carbon contaminations on the optical constants of capping layers and the impact of neighboring atoms' interactions on optical responses of Si and Mo layers are discussed.

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

2016-10-01

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.

Flexural Fatigue Behavior of an EBC CMC Composite System In Air and Steam at High Temperature

NASA Technical Reports Server (NTRS)

Jaskowiak, Martha; Bur, Michael; Harder, Bryan; Gorican, Daniel

2017-01-01

Both coated and uncoated SiCSiC ceramic matrix composite (CMC) samples were tested in flexure under sustained peak low cycle fatigue (SPLCF) conditions in air or steam at elevated temperatures. The SiCSiC composites were reinforced with 2-D plies of boron nitride coated Hi-Nicalon Type-S SiC fibers which were woven as 5 harness satin (5HS) cloth. The composites were densified by chemical vapor infiltration (CVI) followed by slurry melt infiltration (SMI). A multilayer barium strontium aluminosilicate (BSAS) coating was applied to the samples by a plasma spray method. Fatigue loading limits were determined from monotonic flexure tests at room temperature and 1200oC. Stress levels under the proportional limit of the composite material were selected for the SPLCF tests. After cyclic testing, the composites were evaluated to determine crack propagation and failure modes in the coated and uncoated composites. Microstructural examination was used to identify coating degradation and failure modes of the EBCCMC system.

Numerical simulation of multi-layered textile composite reinforcement forming

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 workmore » 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.« less

Method for fabricating an ignitable heterogeneous stratified metal structure

DOEpatents

Barbee, T.W. Jr.; Weihs, T.

1996-08-20

A multilayer structure has a selectable: (1) propagating reaction front velocity V; (2) reaction initiation temperature attained by application of external energy; and (3) amount of energy delivered by a reaction of alternating unreacted layers of the multilayer structure. Because V is selectable and controllable, a variety of different applications for the multilayer structures are possible, including but not limited to their use as igniters, in joining applications, in fabrication of new materials, as smart materials and in medical applications and devices. The multilayer structure has a period D, and an energy release rate constant K. Two or more alternating unreacted layers are made of different materials and separated by reacted zones. The period D is equal to a sum of the widths of each single alternating reaction layer of a particular material, and also includes a sum of reacted zone widths, t{sub i}, in the period D. The multilayer structure has a selectable propagating reaction front velocity V, where V=K(1/D{sup n}){times}[1-(t{sub i}/D)] and n is about 0.8 to 1.2. 8 figs.

Method for fabricating an ignitable heterogeneous stratified metal structure

DOEpatents

Barbee, Jr., Troy W.; Weihs, Timothy

1996-01-01

A multilayer structure has a selectable, (i) propagating reaction front velocity V, (ii) reaction initiation temperature attained by application of external energy and (iii) amount of energy delivered by a reaction of alternating unreacted layers of the multilayer structure. Because V is selectable and controllable, a variety of different applications for the multilayer structures are possible, including but not limited to their use as ignitors, in joining applications, in fabrication of new materials, as smart materials and in medical applications and devices. The multilayer structure has a period D, and an energy release rate constant K. Two or more alternating unreacted layers are made of different materials and separated by reacted zones. The period D is equal to a sum of the widths of each single alternating reaction layer of a particular material, and also includes a sum of reacted zone widths, t.sub.i, in the period D. The multilayer structure has a selectable propagating reaction front velocity V, where V=K(1/D.sup.n).times.[1-(t.sub.i /D)]and n is about 0.8 to 1.2.

A transmission electron microscopy study of the deformation behavior underneath nanoindents in nanoscale Al-TiN multilayered composites

NASA Astrophysics Data System (ADS)

Bhattacharyya, D.; Mara, N. A.; Dickerson, P.; Hoagland, R. G.; Misra, A.

2010-05-01

Nanoscale multilayered Al-TiN composites were deposited using the dc magnetron sputtering technique in two different layer thickness ratios, Al : TiN = 1 : 1 and Al : TiN = 9 : 1. The Al layer thickness varied from 2 nm to 450 nm. The hardness of the samples was tested by nanoindentation using a Berkovich tip. Cross-sectional transmission electron microscopy (TEM) was carried out on samples extracted with focused ion beam from below the nanoindents. The results of the hardness tests on the Al-TiN multilayers with two different thickness ratios are presented, together with observations from the cross-sectional TEM studies of the regions underneath the indents. These studies revealed remarkable strength in the multilayers, as well as some very interesting deformation behavior in the TiN layers at extremely small length scales, where the hard TiN layers undergo co-deformation with the Al layers.

Material optimization of multi-layered enhanced nanostructures

NASA Astrophysics Data System (ADS)

Strobbia, Pietro

The employment of surface enhanced Raman scattering (SERS)-based sensing in real-world scenarios will offer numerous advantages over current optical sensors. Examples of these advantages are the intrinsic and simultaneous detection of multiple analytes, among many others. To achieve such a goal, SERS substrates with throughput and reproducibility comparable to commonly used fluorescence sensors have to be developed. To this end, our lab has discovered a multi-layer geometry, based on alternating films of a metal and a dielectric, that amplifies the SERS signal (multi-layer enhancement). The advantage of these multi-layered structures is to amplify the SERS signal exploiting layer-to-layer interactions in the volume of the structures, rather than on its surface. This strategy permits an amplification of the signal without modifying the surface characteristics of a substrate, and therefore conserving its reproducibility. Multi-layered structures can therefore be used to amplify the sensitivity and throughput of potentially any previously developed SERS sensor. In this thesis, these multi-layered structures were optimized and applied to different SERS substrates. The role of the dielectric spacer layer in the multi-layer enhancement was elucidated by fabricating spacers with different characteristics and studying their effect on the overall enhancement. Thickness, surface coverage and physical properties of the spacer were studied. Additionally, the multi-layered structures were applied to commercial SERS substrates and to isolated SERS probes. Studies on the dependence of the multi-layer enhancement on the thickness of the spacer demonstrated that the enhancement increases as a function of surface coverage at sub-monolayer thicknesses, due to the increasing multi-layer nature of the substrates. For fully coalescent spacers the enhancement decreases as a function of thickness, due to the loss of interaction between proximal metallic films. The influence of the physical properties of the spacer on the multi-layer enhancement were also studied. The trends in Schottky barrier height, interfacial potential and dielectric constant were isolated by using different materials as spacers (i.e., TiO2, HfO2, Ag 2O and Al2O3). The results show that the bulk dielectric constant of the material can be used to predict the relative magnitude of the multi-layer enhancement, with low dielectric constant materials performing more efficiently as spacers. Optimal spacer layers were found to be ultrathin coalescent films (ideally a monolayer) of low dielectric constant materials. Finally, multi-layered structures were observed to be employable to amplify SERS in drastically different substrate geometries. The multi-layered structures were applied to disposable commercial SERS substrates (i.e., Klarite). This project involved the regeneration of the used substrates, by stripping and redepositing the gold coating layer, and their amplification, by using the multi-layer geometry. The latter was observed to amplify the sensitivity of the substrates. Additionally, the multi-layered structures were applied to probes dispersed in solution. Such probes were observed to yield stronger SERS signal when optically trapped and to reduce the background signal. The application of the multi-layered structures on trapped probes, not only further amplified the SERS signal, but also increased the maximum number of applicable layers for the structures.

Multilayer dielectric diffraction gratings

DOEpatents

Perry, Michael D.; Britten, Jerald A.; Nguyen, Hoang T.; Boyd, Robert; Shore, Bruce W.

1999-01-01

The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

Multilayer dielectric diffraction gratings

DOEpatents

Perry, M.D.; Britten, J.A.; Nguyen, H.T.; Boyd, R.; Shore, B.W.

1999-05-25

The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described. 7 figs.

Formation of He-Rich Layers Observed by Neutron Reflectometry in the He-Ion-Irradiated Cr/W Multilayers: Effects of Cr/W Interfaces on the He-Trapping Behavior.

PubMed

Chen, Feida; Tang, Xiaobin; Huang, Hai; Li, Xinxi; Wang, Yan; Huang, Chaoqiang; Liu, Jian; Li, Huan; Chen, Da

2016-09-21

Cr/W multilayer nanocomposites were presented in the paper as potential candidate materials for the plasma facing components in fusion reactors. We used neutron reflectometry to measure the depth profile of helium in the multienergy He ions irradiated [Cr/W (50 nm)]3 multilayers. Results showed that He-rich layers with low neutron scattering potential energy form at the Cr/W interfaces, which is in great agreement with previous modeling results of other multilayers. This phenomenon provided a strong evidence for the He trapping effects of Cr/W interfaces and implied the possibility of using the Cr/W multilayer nanocomposites as great He-tolerant plasma facing materials.

Stress evolution of Ge nanocrystals in dielectric matrices.

PubMed

Bahariqushchi, Rahim; Raciti, Rosario; Kasapoğlu, Ahmet Emre; Gür, Emre; Sezen, Meltem; Kalay, Eren; Mirabella, Salvatore; Aydinli, A

2018-05-04

Germanium nanocrystals (Ge NCs) embedded in single and multilayer silicon oxide and silicon nitride matrices have been synthesized using plasma enhanced chemical vapor deposition followed by conventional furnace annealing or rapid thermal processing in N 2 ambient. Compositions of the films were determined by Rutherford backscattering spectrometry and x-ray photoelectron spectroscopy. The formation of NCs under suitable process conditions was observed with high resolution transmission electron microscope micrographs and Raman spectroscopy. Stress measurements were done using Raman shifts of the Ge optical phonon line at 300.7 cm -1 . The effect of the embedding matrix and annealing methods on Ge NC formation were investigated. In addition to Ge NCs in single layer samples, the stress on Ge NCs in multilayer samples was also analyzed. Multilayers of Ge NCs in a silicon nitride matrix separated by dielectric buffer layers to control the size and density of NCs were fabricated. Multilayers consisted of SiN y :Ge ultrathin films sandwiched between either SiO 2 or Si 3 N 4 by the proper choice of buffer material. We demonstrated that it is possible to tune the stress state of Ge NCs from compressive to tensile, a desirable property for optoelectronic applications. We also observed that there is a correlation between the stress and the crystallization threshold in which the compressive stress enhances the crystallization, while the tensile stress suppresses the process.

Stress evolution of Ge nanocrystals in dielectric matrices

NASA Astrophysics Data System (ADS)

Bahariqushchi, Rahim; Raciti, Rosario; Emre Kasapoğlu, Ahmet; Gür, Emre; Sezen, Meltem; Kalay, Eren; Mirabella, Salvatore; Aydinli, A.

2018-05-01

Germanium nanocrystals (Ge NCs) embedded in single and multilayer silicon oxide and silicon nitride matrices have been synthesized using plasma enhanced chemical vapor deposition followed by conventional furnace annealing or rapid thermal processing in N2 ambient. Compositions of the films were determined by Rutherford backscattering spectrometry and x-ray photoelectron spectroscopy. The formation of NCs under suitable process conditions was observed with high resolution transmission electron microscope micrographs and Raman spectroscopy. Stress measurements were done using Raman shifts of the Ge optical phonon line at 300.7 cm-1. The effect of the embedding matrix and annealing methods on Ge NC formation were investigated. In addition to Ge NCs in single layer samples, the stress on Ge NCs in multilayer samples was also analyzed. Multilayers of Ge NCs in a silicon nitride matrix separated by dielectric buffer layers to control the size and density of NCs were fabricated. Multilayers consisted of SiN y :Ge ultrathin films sandwiched between either SiO2 or Si3N4 by the proper choice of buffer material. We demonstrated that it is possible to tune the stress state of Ge NCs from compressive to tensile, a desirable property for optoelectronic applications. We also observed that there is a correlation between the stress and the crystallization threshold in which the compressive stress enhances the crystallization, while the tensile stress suppresses the process.

Electrochemical Studies of Graphene-like materials Synthesized by the Thermolyzed Asphalt Reaction

NASA Astrophysics Data System (ADS)

Xie, Yuqun

Developing a facile and cost effective synthetic method for producing graphene materials has been an attractive research topic in several disciplines. Chapter 3 demenstrates sheets of multilayered graphene-like paper materials more than 10 cm2 in area were synthesized in the "Thermolyzed Asphalt Reaction (TAR)". TAR is processed within open containers at 650 °C under atmospheric pressure without the need to exclude oxygen, which is the lowest reported temperature for chemical vapor deposition of graphene-based materials. It was found that multilayered graphene-like materials can be grown on amorphous substrates without catalysts. In chapter 4, further studies of the TAR mechanism have allowed sulfur to be identified as an important co-factor in multilayer graphene-like materials formation. Graphene-like material was produced from simple precursors such as elemental sulfur and cyclohexanol. A proposed scheme illustrates sulfur's role in the growth of graphene-like material based on thermogravimetric analyses. We hypothesize that elemental sulfur is involved with the dehydration/dehydrogenation and eventual crosslinking of cyclohexanol between 100-140 °C. In the range of 240-400 °C further dehydrogenation steps occur yielding an unidentified intermediate with a sharp Raman peak at 1450 cm-1 At 550 °C graphene-like Raman D and G bands appear along with the 1450 cm band of the intermediate. At 600 °C and higher temperatures, the intermediate peak is lost with only bands characteristic of graphene-like material being seen in the spectrum of the material synthesized from the University of Idaho Thermolyzed Asphalt Reaction (GUITAR). Sulfur as a key co-factor for GUITAR synthesis is reinforced by results found with other hydrocarbons. Other organics succeeded or failed in GUITAR formation based on melting and boiling considerations. The failure of the compounds with a boiling point below -89°C, melting point above 300°C is reasoned with the volatility of the dehydration products and lacking of sulfur cross-linking in solid state. Chapter 5 established GUITAR as a suitable material for dimensionally stable anodes (DSAs) because of its remarkable anodic stability revealed by electrochemical characterization. Cyclic voltammetric evaluation of GUITAR with Ru(NH3)63+/2+ and Fe(CN)6 3-/4- redox couples suggests that GUITAR enables faster electron transfer than chemical vapor deposition (CVD) grown graphene and highly ordered pyrolytic graphite (HOPG), even though GUITAR shares a common morphological phenomenon with HOPG, namely an atomically flat basal plane. At a current density of 200 muAcm -2, the anodic limit of GUITAR is 2.7 V vs SHE in 1MH2SO 4, GUITAR as a new material for DSAs was reinforced by its performance on methylene blue degradation, the normalized methylene blue degradation rate constant obtained with GUITAR was 10 times higher than that of boron doped dimond anode. In chapter 6, GUITAR formed on the surface of silica nanosprings composites was employed as the electrode material for an ultracapacitor. A 2.35 nm thin graphene film on the silica nanosprings surface offered a straight electron path through the high surface area of the silica nanosprings. Additionally, the high porosity of the silica nanosprings backbone enables facile electrolyte access to the graphene surface, resulting in the maxmum surface area utilization of a graphene-like films coated silica nanosprings composite electrode. The specific capacitance of 337 F g-1 was obtained in a concentrated H2SO4 electrolyte with a scan rate of 0.01 Vs -1. Nearly perfect capacitive behavior was observed with symmetric static charge /discharge curves at various current rates. A low equivalent series resistance (0.4 O) was measured with graphenelike silica nanosprings composites configured as an ultracapacitor. Superior electrochemical performance of graphene-like silica nanosprings composites as the electrode of an ultracapacitor was achieved when compared to ultracapacitors based on reduced graphene oxide and carbon nano-tubes.

Comparison and preparation of multilayered polylactic acid fabric strengthen calcium phosphate-based bone substitutes for orthopedic applications.

PubMed

Chen, Wen-Cheng; Ko, Chia-Ling; Yang, Jia-Kai; Wu, Hui-Yu; Lin, Jia-Horng

2016-03-01

An attempt to maintain the three-dimensional space into restorative sites through the conveniently pack porous fillers are general used strategy. Advancement in the manufacturing protective shells in the scaffolds, which would be filled with brittle ceramic grafts for the development of highly connective pores provides the approach to solve crack problem for generating the tissues. Therefore, multilayered braided and alkalized poly(lactic acid) (PLA) composites with calcium phosphate bone cement (CPC) were synthesized and compared. The PLA/CPC composites were divided into various groups according to a series of heat-treatment temperatures (100-190 °C) and periods (1-3 h) and then characterized. The effects of 24-h immersion on the strength decay resistance of the samples were compared. Results showed that the residual oil capped on the surfaces of alkalized PLA braid was removed, and the structure was unaltered. However, the reduced tensile stress of alkalized PLA braids was due to ester-group formation by hydrolysis. Mechanical test results of PLA/CPC composites showed that the strength significantly increased after heat treatment, except when the heating temperature was higher than the PLA melting point at approximately 160-170 °C. The degree of PLA after recrystallization became higher than that of unheated composites, thereby leading to reduced strength and toughness of the specimen. Braiding fibers of biodegradable PLA reinforced and toughened the structure particularly of the extra-brittle material of thin-sheet CPC after implantation.

The mechanical behavior of nanoscale metallic multilayers: A survey

NASA Astrophysics Data System (ADS)

Zhou, Q.; Xie, J. Y.; Wang, F.; Huang, P.; Xu, K. W.; Lu, T. J.

2015-06-01

The mechanical behavior of nanoscale metallic multilayers (NMMs) has attracted much attention from both scientific and practical views. Compared with their monolithic counterparts, the large number of interfaces existing in the NMMs dictates the unique behavior of this special class of structural composite materials. While there have been a number of reviews on the mechanical mechanism of microlaminates, the rapid development of nanotechnology brought a pressing need for an overview focusing exclusively on a property-based definition of the NMMs, especially their size-dependent microstructure and mechanical performance. This article attempts to provide a comprehensive and up-to-date review on the microstructure, mechanical property and plastic deformation physics of NMMs. We hope this review could accomplish two purposes: (1) introducing the basic concepts of scaling and dimensional analysis to scientists and engineers working on NMM systems, and (2) providing a better understanding of interface behavior and the exceptional qualities the interfaces in NMMs display at atomic scale.

Comparison of the morphology, chemical composition and microstructure of cryptocrystalline graphite and carbon black

NASA Astrophysics Data System (ADS)

Quan, Ying; Liu, Qinfu; Zhang, Shilong; Zhang, Shuai

2018-07-01

The structures of cryptocrystalline graphite (CG) and carbon black (CB) have been analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), organic elemental analysis (OEA), X-ray diffraction (XRD), RAMAN and high-resolution transmission electron microscopy (HRTEM). These results indicate that CG has the same elemental composition as CB, with carbon being the major element present. SL sample (CG with low graphitization degree) and CB exhibit similar microcrystalline structures. CG was shown to contain a layered graphitic structure that was significantly different to the primary spherical particles present in CB. It is proposed that these CG sheets may potentially be reduced and delaminated to afford multilayer graphene structures with improved material properties.

A diffusion-limited reaction model for self-propagating Al/Pt multilayers with quench limits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kittell, David E.; Yarrington, Cole D.; Hobbs, M. L.

A diffusion-limited reaction model was calibrated for Al/Pt multilayers ignited on oxidized silicon, sapphire, and tungsten substrates, as well as for some Al/Pt multilayers ignited as free-standing foils. The model was implemented in a finite element analysis code and used to match experimental burn front velocity data collected from several years of testing at Sandia National Laboratories. Moreover, both the simulations and experiments reveal well-defined quench limits in the total Al + Pt layer (i.e., bilayer) thickness. At these limits, the heat generated from atomic diffusion is insufficient to support a self-propagating wave front on top of the substrates. Quenchmore » limits for reactive multilayers are seldom reported and are found to depend on the thermal properties of the individual layers. Here, the diffusion-limited reaction model is generalized to allow for temperature- and composition-dependent material properties, phase change, and anisotropic thermal conductivity. Utilizing this increase in model fidelity, excellent overall agreement is shown between the simulations and experimental results with a single calibrated parameter set. However, the burn front velocities of Al/Pt multilayers ignited on tungsten substrates are over-predicted. Finally, possible sources of error are discussed and a higher activation energy (from 41.9 kJ/mol.at. to 47.5 kJ/mol.at.) is shown to bring the simulations into agreement with the velocity data observed on tungsten substrates. Finally, this higher activation energy suggests an inhibited diffusion mechanism present at lower heating rates.« less

A diffusion-limited reaction model for self-propagating Al/Pt multilayers with quench limits

DOE PAGES

Kittell, David E.; Yarrington, Cole D.; Hobbs, M. L.; ...

2018-04-14

A diffusion-limited reaction model was calibrated for Al/Pt multilayers ignited on oxidized silicon, sapphire, and tungsten substrates, as well as for some Al/Pt multilayers ignited as free-standing foils. The model was implemented in a finite element analysis code and used to match experimental burn front velocity data collected from several years of testing at Sandia National Laboratories. Moreover, both the simulations and experiments reveal well-defined quench limits in the total Al + Pt layer (i.e., bilayer) thickness. At these limits, the heat generated from atomic diffusion is insufficient to support a self-propagating wave front on top of the substrates. Quenchmore » limits for reactive multilayers are seldom reported and are found to depend on the thermal properties of the individual layers. Here, the diffusion-limited reaction model is generalized to allow for temperature- and composition-dependent material properties, phase change, and anisotropic thermal conductivity. Utilizing this increase in model fidelity, excellent overall agreement is shown between the simulations and experimental results with a single calibrated parameter set. However, the burn front velocities of Al/Pt multilayers ignited on tungsten substrates are over-predicted. Finally, possible sources of error are discussed and a higher activation energy (from 41.9 kJ/mol.at. to 47.5 kJ/mol.at.) is shown to bring the simulations into agreement with the velocity data observed on tungsten substrates. Finally, this higher activation energy suggests an inhibited diffusion mechanism present at lower heating rates.« less

Structure and Properties of High-Temperature Multilayer Hybrid Material Based on Vanadium Alloy and Stainless Steel

NASA Astrophysics Data System (ADS)

Nechaykina, Tatyana A.; Nikulin, Sergey A.; Rozhnov, Andrey B.; Khatkevich, Vladimir M.; Rogachev, Stanislav O.

2017-03-01

The present work is devoted to the development of new structural composite material having the unique complex of properties for operating in ultrahard conditions that combine high temperatures, radiation, and aggressive environments. A new three-layer composite tube material based on vanadium alloy (V-4Ti-4Cr) protected by stainless steel (Fe-0.2C-13Cr) has been obtained by co-extrusion. Mechanism and kinetics of formation as well as structure, composition, and mechanical properties of "transition" area between vanadium alloy and stainless steel have been studied. The transition area (13- to 22- µm thick) of the diffusion interaction between vanadium alloy and steel was formed after co-extrusion. The microstructure in the transition area was rather complicated comprising different grain sizes in components, but having no defects or brittle phases. Tensile strength of the composite was an average 493 ± 22 MPa, and the elongation was 26 ± 3 pct. Annealing at 1073 K (800 °C) increased the thickness of transition area up to 1.2 times, homogenized microstructure, and slightly changed mechanical properties. Annealing at 1273 K (1000 °C) further increased the thickness of transition area and also lead to intensive grain growth in steel and sometimes to separation between composite components during tensile tests. Annealing at 1073 K (800 °C) is proposed as appropriate heat treatment after co-extrusion of composite providing balance between diffusion interaction thickness and microstructure and monolithic-like behavior of composite during tensile tests.

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

NASA Astrophysics Data System (ADS)

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

2014-10-01

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 1×10-4 to 1.2×10-3 M with the detect limit of 5×10-6 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.

Depth estimation of multi-layered impact damage in PMC using lateral thermography

NASA Astrophysics Data System (ADS)

Whitlow, Travis; Kramb, Victoria; Reibel, Rick; Dierken, Josiah

2018-04-01

Characterization of impact damage in polymer matrix composites (PMCs) continues to be a challenge due to the complex internal structure of the material. Nondestructive characterization approaches such as normal incident immersion ultrasound and flash thermography are sensitive to delamination damage, but do not provide information regarding damage obscured by the delaminations. Characterization of material state below a delamination requires a technique which is sensitive to in-plane damage modes such as matrix cracking and fiber breakage. Previous studies of the lateral heat flow through a composite laminate showed that the diffusion time was sensitive to the depth of the simulated damage zone. The current study will further evaluate the lateral diffusion model to provide sensitivity limits for the modeled flaw dimensions. Comparisons between the model simulations and experimental data obtained using a concentrated heat source and machined targets will also be presented.

The Structure Of The Gaia Deployable Sunshield Assembly

NASA Astrophysics Data System (ADS)

Pereira, Carlos; Urgoiti, Eduardo; Pinto, Inaki

2012-07-01

GAIA is an ESA mission with launch date in 2013. Its main objective is to map the stars. After launch it will unfold a 10.2 m diameter sunshield .The structure of this shield consists of twelve 3.5 meter long composite trusses which act as scaffold to two multilayer insulation blankets. Due to thermal stability constraints the planarity of the shield must be better than 1.0 mm. The trusses are therefore lightweight structures capable of withstanding the launch loads and once deployed, the thermal environment of the spacecraft with a minimum of distortion. This paper details: • The material selection for the composite structure • Validation of the chosen materials and truss layout • The modification of manufacturing process in order to lightweight the structure • The extensive structural and thermal stability testing The sunshield has been delivered to the satellite prime after successful mechanical, thermal and deployment tests.

Hybrid Laminates for Application in North Conditions

NASA Astrophysics Data System (ADS)

Antipov, V. V.; Oreshko, E. I.; Erasov, V. S.; Serebrennikova, N. Yu.

2016-11-01

A hybrid aluminum-lithium alloy/SIAL laminate as a possible material for application in structures operated in North conditions is considered. The finite-element method is used for a buckling stability analysis of hybrid panels, bars, and plates. A technique allowing one to compare the buckling stability of multilayered hybrid plates is offered. Compression tests were run on a hybrid laminate wing panel as a prototype of the top panel of TU-204SM airplane made from a high-strength B95T2 aluminum alloy. It turned out that the lighter composite panel had a higher load-carrying capacity than the aluminum one. Results of investigation into the properties the hybrid aluminum-lithium alloy/SIAL laminate and an analysis of scientific-technical data on this subject showed that this composite material could be used in the elements of airframes, including those operated in north conditions.

Minimal invasive control of paintings cleaning by LIBS

NASA Astrophysics Data System (ADS)

Staicu, A.; Apostol, I.; Pascu, A.; Urzica, I.; Pascu, M. L.; Damian, V.

2016-03-01

In cultural heritage restoration and conservation, it has been proved that LIBS is an appropriate technique for pigments identification, analysis of multilayered paintings, and quantitative analysis of ancient materials. Generally, experiments involving the use of laser for paint cleaning and LIBS in order to identify the composition of the removed material are made. Here, we report LIBS studies on mastic and dammar varnishes removal using visible (532 nm) and UV (266 nm) laser pulses (5 ns) with fluences in the range 0.6-4.4 J/cm2. The studied varnish layers were on-purpose painted on glass supports or were part of several mock-up samples having dammar or mastic as final layer - gold foil, yellow ochre or cobalt blue egg tempera as painting layer - chalk or acrylic ground as link to an wooden support. LIBS was used to monitor the laser induced stepwise selective removal of the layers and to analyze their composition.

Processing, Structure and High Temperature Oxidation Properties of Polymer-Derived and Hafnium Oxide Based Ceramic Systems

NASA Astrophysics Data System (ADS)

Terauds, Kalvis

Demands for hypersonic aircraft are driving the development of ultra-high temperature structural materials. These aircraft, envisioned to sustain Mach 5+, are expected to experience continuous temperatures of 1200--1800°C on the aircraft surface and temperatures as high as 2800°C in combustion zones. Breakthroughs in the development of fiber based ceramic matrix composites (CMCs) are opening the door to a new class of high-tech UHT structures for aerospace applications. One limitation with current carbon fiber or silicon carbide fiber based CMC technology is the inherent problem of material oxidation, requiring new approaches for protective environmental barrier coatings (EBC) in extreme environments. This thesis focuses on the development and characterization of SiCN-HfO2 based ceramic composite EBC systems to be used as a protective layer for silicon carbide fiber based CMCs. The presented work covers three main architectures for protection (i) multilayer films, (ii) polymer-derived HfSiCNO, and (iii) composite SiCN-HfO 2 infiltration. The scope of this thesis covers processing development, material characterization, and high temperature oxidation behavior of these three SiCN-HfO2 based systems. This work shows that the SiCN-HfO 2 composite materials react upon oxidation to form HfSiO4, offering a stable EBC in streaming air and water vapor at 1600°C.

Design and characterization of terahertz-absorbing nano-laminates of dielectric and metal thin films.

PubMed

Bolakis, C; Grbovic, D; Lavrik, N V; Karunasiri, G

2010-07-05

A terahertz-absorbing thin-film stack, containing a dielectric Bragg reflector and a thin chromium metal film, was fabricated on a silicon substrate for applications in bi-material terahertz (THz) sensors. The Bragg reflector is to be used for optical readout of sensor deformation under THz illumination. The THz absorption characteristics of the thin-film composite were measured using Fourier transform infrared spectroscopy. The absorption of the structure was calculated both analytically and by finite element modeling and the two approaches agreed well. Finite element modeling provides a convenient way to extract the amount of power dissipation in each layer and is used to quantify the THz absorption in the multi-layer stack. The calculation and the model were verified by experimentally characterizing the multi-layer stack in the 3-5 THz range. The measured and simulated absorption characteristics show a reasonably good agreement. It was found that the composite film absorbed about 20% of the incident THz power. The model was used to optimize the thickness of the chromium film for achieving high THz absorption and found that about 50% absorption can be achieved when film thickness is around 9 nm.

Thin film characterization by laser interferometry combined with SIMS

NASA Astrophysics Data System (ADS)

Kempf, J.; Nonnenmacher, M.; Wagner, H. H.

1988-10-01

Thin film properties of technologically important materials (Si, GaAs, SiO2, WSix) have been measured by using a novel technique that combines secondary ion mass spectrometry (SIMS) and laser interferometry. The simultaneous measurement of optical phase and reflectance as well as SIMS species during ion sputtering yielded optical constants, sputtering rates and composition of thin films with high depth resolution. A model based on the principle of multiple reflection within a multilayer structure, which considered also transformation of the film composition in depth and time during sputtering, was fitted to the reflectance and phase data. This model was applied to reveal the transformation of silicon by sputtering with O{2/+} ions. Special attention was paid to the preequilibrium phase of the sputter process (amorphization, oxidation, and volume expansion). To demonstrate the analytical potential of our method the multilayer system WSix/poly-Si/SiO2/Si was investigated. The physical parameters and the stoichiometry of tungsten suicide were determined for annealed as well as deposited films. A highly sensitive technique that makes use of a Fabry-Perot etalon integrated with a Michelson type interferometer is proposed. This two-stage interferometer has the potential to profile a sample surface with subangstroem resolution.

Multilayered Al/CuO thermite formation by reactive magnetron sputtering: Nano versus micro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrantoni, M.; Rossi, C.; Salvagnac, L.

2010-10-15

Multilayered Al/CuO thermite was deposited by a dc reactive magnetron sputtering method. Pure Al and Cu targets were used in argon-oxygen gas mixture plasma and with an oxygen partial pressure of 0.13 Pa. The process was designed to produce low stress (<50 MPa) multilayered nanoenergetic material, each layer being in the range of tens nanometer to one micron. The reaction temperature and heat of reaction were measured using differential scanning calorimetry and thermal analysis to compare nanostructured layered materials to microstructured materials. For the nanostructured multilayers, all the energy is released before the Al melting point. In the case ofmore » the microstructured samples at least 2/3 of the energy is released at higher temperatures, between 1036 and 1356 K.« less

Super-hydrophobic multilayer coatings with layer number tuned swapping in surface wettability and redox catalytic anti-corrosion application.

PubMed

Syed, Junaid Ali; Tang, Shaochun; Meng, Xiangkang

2017-06-30

The wetting characteristic of a metal surface can be controlled by employing different coating materials and external stimuli, however, layer number (n) modulated surface swapping between hydrophobicity and hydrophilicity in a multilayer structure to achieve prolonged anti-corrosion ability was not taken into consideration. In this study, we proposed a layer-by-layer (LbL) spin assembled polyaniline-silica composite/tetramethylsilane functionalized silica nanoparticles (PSC/TMS-SiO 2 ) coating with the combined effect of super-hydrophobicity and enhanced anti-corrosion ability. Interestingly, the hierarchical integration of two coating materials with inherently different surface roughness and energy in a multilayer structure allows the wetting feature to swap from hydrophobic to hydrophilic state by modulating n with decreasing hydrophilicity. The samples with odd n (TMS-SiO 2 surface) are hydrophobic while the samples with even n (PSC surface) exhibits the hydrophilic character. The TMS-SiO 2 content was optimized to achieve super-hydrophobic coating with significantly high water contact angle (CA) 153° ± 2° and small sliding angle (SA) 6° ± 2°. Beside its self-cleaning behavior, the electro-active PSC/TMS-SiO 2 coating also exhibits remarkably enhanced corrosion resistance against aggressive media. The corrosion resistance of the coating was remained stable even after 240 h of exposure, this enhancement is attributed to super-hydrophobicity and anodic shift in corrosion potential.

Low Voltage Electrowetting-on-Dielectric Platform using Multi-Layer Insulators

PubMed Central

Lin, Yan-You; Evans, Randall D.; Welch, Erin; Hsu, Bang-Ning; Madison, Andrew C.; Fair, Richard B.

2010-01-01

A low voltage, two-level-metal, and multi-layer insulator electrowetting-on-dielectric (EWD) platform is presented. Dispensing 300pl droplets from 140nl closed on-chip reservoirs was accomplished with as little as 11.4V solely through EWD forces, and the actuation threshold voltage was 7.2V with a 1Hz voltage switching rate between electrodes. EWD devices were fabricated with a multilayer insulator consisting of 135nm sputtered tantalum pentoxide (Ta2O5) and 180nm parylene C coated with 70nm of CYTOP. Furthermore, the minimum actuation threshold voltage followed a previously published scaling model for the threshold voltage, VT, which is proportional to (t/εr)1/2, where t and εr are the insulator thickness and dielectric constant respectively. Device threshold voltages are compared for several insulator thicknesses (200nm, 500nm, and 1µm), different dielectric materials (parylene C and tantalum pentoxide), and homogeneous versus heterogeneous compositions. Additionally, we used a two-level-metal fabrication process, which enables the fabrication of smaller and denser electrodes with high interconnect routing flexibility. We also have achieved low dispensing and actuation voltages for scaled devices with 30pl droplets. PMID:20953362

Q-factor control of multilayer micromembrane using PZT composite material

NASA Astrophysics Data System (ADS)

Čekas, Elingas; Janušas, Giedrius; Palevicius, Arvydas; Janušas, Tomas; Ciganas, Justas

2018-02-01

Cantilever and membrane based sensors, which are capable of providing accurate detection of target analytes have been always an important research topic of medical diagnostics, food testing, and environmental monitoring fields. Here, the mechanical detection is achieved by micro- and nano-scale cantilevers for stress sensing and mass sensing, or micro- and nano-scale plates or membranes. High sensitivity is a major issue for the active element and it could be achieved via increased Q-factor. The ability to control the Q factor expands the range of application of the device and allows to achieve more accurate results. The aim of this paper is to investigate the mechanical and electrical properties, as well as, the ability to control the Q factor of the membrane with PZT nanocomposite. This multilayered membrane was formatted using the n-type <100> silicon substrate by implementing the Low Pressure Chemical Vapor Deposition (LPCVD), photolithography by using photomask with defined dimensions, deep etching, and e-beam evaporation techniques. Dynamic and electrical characteristics of the membrane were numerically investigated using COMSOL Multiphysics software. The use of the multilayered membrane can range from simple monitoring of particles concentration in a closed environment to inspecting glucose levels in human fluids (blood, tears, sweat, etc.).

Flexible Ferroelectric Sensors with Ultrahigh Pressure Sensitivity and Linear Response over Exceptionally Broad Pressure Range.

PubMed

Lee, Youngoh; Park, Jonghwa; Cho, Soowon; Shin, Young-Eun; Lee, Hochan; Kim, Jinyoung; Myoung, Jinyoung; Cho, Seungse; Kang, Saewon; Baig, Chunggi; Ko, Hyunhyub

2018-04-24

Flexible pressure sensors with a high sensitivity over a broad linear range can simplify wearable sensing systems without additional signal processing for the linear output, enabling device miniaturization and low power consumption. Here, we demonstrate a flexible ferroelectric sensor with ultrahigh pressure sensitivity and linear response over an exceptionally broad pressure range based on the material and structural design of ferroelectric composites with a multilayer interlocked microdome geometry. Due to the stress concentration between interlocked microdome arrays and increased contact area in the multilayer design, the flexible ferroelectric sensors could perceive static/dynamic pressure with high sensitivity (47.7 kPa -1 , 1.3 Pa minimum detection). In addition, efficient stress distribution between stacked multilayers enables linear sensing over exceptionally broad pressure range (0.0013-353 kPa) with fast response time (20 ms) and high reliability over 5000 repetitive cycles even at an extremely high pressure of 272 kPa. Our sensor can be used to monitor diverse stimuli from a low to a high pressure range including weak gas flow, acoustic sound, wrist pulse pressure, respiration, and foot pressure with a single device.

Alkali resistant optical coatings for alkali lasers and methods of production thereof

DOEpatents

Soules, Thomas F; Beach, Raymond J; Mitchell, Scott C

2014-11-18

In one embodiment, a multilayer dielectric coating for use in an alkali laser includes two or more alternating layers of high and low refractive index materials, wherein an innermost layer includes a thicker, >500 nm, and dense, >97% of theoretical, layer of at least one of: alumina, zirconia, and hafnia for protecting subsequent layers of the two or more alternating layers of high and low index dielectric materials from alkali attack. In another embodiment, a method for forming an alkali resistant coating includes forming a first oxide material above a substrate and forming a second oxide material above the first oxide material to form a multilayer dielectric coating, wherein the second oxide material is on a side of the multilayer dielectric coating for contacting an alkali.

Redox-controlled molecular permeability of composite-wall microcapsules

NASA Astrophysics Data System (ADS)

Ma, Yujie; Dong, Wen-Fei; Hempenius, Mark A.; Möhwald, Helmuth; Julius Vancso, G.

2006-09-01

Many smart materials in bioengineering, nanotechnology and medicine allow the storage and release of encapsulated drugs on demand at a specific location by an external stimulus. Owing to their versatility in material selection, polyelectrolyte multilayers are very promising systems in the development of microencapsulation technologies with permeation control governed by variations in the environmental conditions. Here, organometallic polyelectrolyte multilayer capsules, composed of polyanions and polycations of poly(ferrocenylsilane) (PFS), are introduced. Their preparation involved layer-by-layer self-assembly onto colloidal templates followed by core removal. PFS polyelectrolytes feature redox-active ferrocene units in the main chain. Incorporation of PFS into the capsule walls allowed us to explore the effects of a new stimulus, that is, changing the redox state, on capsule wall permeability. The permeability of these capsules could be sensitively tuned via chemical oxidation, resulting in a fast capsule expansion accompanied by a drastic permeability increase in response to a very small trigger. The substantial swelling could be suppressed by the application of an additional coating bearing common redox-inert species of poly(styrene sulfonate) (PSS-) and poly(allylamine hydrochloride) (PAH+) on the outer wall of the capsules. Hence, we obtained a unique capsule system with redox-controlled permeability and swellability with a high application potential in materials as well as in bioscience.

Electron beam transport in heterogeneous slab media from MeV down to eV.

PubMed

Yousfi, M; Leger, J; Loiseau, J F; Held, B; Eichwald, O; Defoort, B; Dupillier, J M

2006-01-01

An optimized Monte Carlo method based on the null collision technique and on the treatment of individual interactions is used for the simulation of the electron transport in multilayer materials from high energies (MeV or several hundred of keV) down to low cutoff energies (between 1 and 10 eV). In order to better understand the electron transport and the energy deposition at the interface in the composite application framework, two layer materials are considered (carbon and polystyrene with densities of 1.7 g cm(-3) and 1.06 g cm(-3), respectively) under two slab or three slab configurations as, e.g. a thin layer of carbon sandwiched between two polystyrene layers. The electron-matter cross-sections (electron-carbon and electron-polystyrene) used in the case of pure material (carbon and polystyrene) as well as our Monte-Carlo code have been first validated. The boundary interface layer is considered without any mean free path truncation and with a rigorous treatment of the backscattered and also the forward scattered electrons from one layer to another. The large effect of the choice of a low cutoff energy and the dissociation process consideration are also clearly shown in the heterogeneous multi-layer media more particularly on the secondary electron emission, inelastic collision number and energy spectra.

Towards nanometric resolution in multilayer depth profiling: a comparative study of RBS, SIMS, XPS and GDOES.

PubMed

Escobar Galindo, Ramón; Gago, Raul; Duday, David; Palacio, Carlos

2010-04-01

An increasing amount of effort is currently being directed towards the development of new functionalized nanostructured materials (i.e., multilayers and nanocomposites). Using an appropriate combination of composition and microstructure, it is possible to optimize and tailor the final properties of the material to its final application. The analytical characterization of these new complex nanostructures requires high-resolution analytical techniques that are able to provide information about surface and depth composition at the nanometric level. In this work, we comparatively review the state of the art in four different depth-profiling characterization techniques: Rutherford backscattering spectroscopy (RBS), secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS) and glow discharge optical emission spectroscopy (GDOES). In addition, we predict future trends in these techniques regarding improvements in their depth resolutions. Subnanometric resolution can now be achieved in RBS using magnetic spectrometry systems. In SIMS, the use of rotating sample holders and oxygen flooding during analysis as well as the optimization of floating low-energy ion guns to lower the impact energy of the primary ions improves the depth resolution of the technique. Angle-resolved XPS provides a very powerful and nondestructive technique for obtaining depth profiling and chemical information within the range of a few monolayers. Finally, the application of mathematical tools (deconvolution algorithms and a depth-profiling model), pulsed sources and surface plasma cleaning procedures is expected to greatly improve GDOES depth resolution.

The preparation and infrared radar stealth performance test of a new paraffin-based phase transition microcapsule

NASA Astrophysics Data System (ADS)

Chen, Yingming; Zhang, Honghong; Gao, Weiting; Chen, Yingmin; Wang, Yifan

2018-04-01

For the problems that the phase change material apply to infrared stealth exists easy to broken, hard to control temperature, narrow infrared channel and based on the basic principles of infrared stealth technology, this paper proposed a scheme of thermal infrared composite invisibility multi-layer wrapping, which based on two sides, one is to control the material surface temperature, another is to reduce its infrared emissivity and combine with visible light pigment and electromagnetic wave absorbing material, to realize the materials' wide band compatible stealth. First, choose urea formaldehyde resin and paraffin to prepare multiphase-change microcapsules, and then combine it with the ferroferric oxide absorbing material, zinc oxide visible light pigment, to make the stealth material of wide band. The experimental results show that the new phase change capsule can realize the function of temperature control and infrared stealth in a special temperature range.

Multilayer core-shell structured composite paper electrode consisting of copper, cuprous oxide and graphite assembled on cellulose fibers for asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Wan, Caichao; Jiao, Yue; Li, Jian

2017-09-01

An easily-operated and inexpensive strategy (pencil-drawing-electrodeposition-electro-oxidation) is proposed to synthesize a novel class of multilayer core-shell structured composite paper electrode, which consists of copper, cuprous oxide and graphite assembled on cellulose fibers. This interesting electrode structure plays a pivotal role in providing more active sites for electrochemical reactions, facilitating ion and electron transport and shorting their diffusion pathways. This electrode demonstrates excellent electrochemical properties with a high specific capacitance of 601 F g-1 at 2 A g-1 and retains 83% of this capacitance when operated at an ultrahigh current density of 100 A g-1. In addition, a high energy density of 13.4 W h kg-1 at the power density of 0.40 kW kg-1 and a favorable cycling stability (95.3%, 8000 cycles) were achieved for this electrode. When this electrode was assembled into an asymmetric supercapacitor with carbon paper as negative electrode, the device displays remarkable electrochemical performances with a large areal capacitances (122 mF cm-2 at 1 mA cm-2), high areal energy density (10.8 μW h cm-2 at 402.5 μW cm-2) and outstanding cycling stability (91.5%, 5000 cycles). These results unveil the potential of this composite electrode as a high-performance electrode material for supercapacitors.

Layer-by-Layer Assembled Architecture of Polyelectrolyte Multilayers and Graphene Sheets on Hollow Carbon Spheres/Sulfur Composite for High-Performance Lithium-Sulfur Batteries.

PubMed

Wu, Feng; Li, Jian; Su, Yuefeng; Wang, Jing; Yang, Wen; Li, Ning; Chen, Lai; Chen, Shi; Chen, Renjie; Bao, Liying

2016-09-14

In the present work, polyelectrolyte multilayers (PEMs) and graphene sheets are applied to sequentially coat on the surface of hollow carbon spheres/sulfur composite by a flexible layer-by-layer (LBL) self-assembly strategy. Owing to the strong electrostatic interactions between the opposite charged materials, the coating agents are very stable and the coating procedure is highly efficient. The LBL film shows prominent impact on the stability of the cathode by acting as not only a basic physical barrier, and more importantly, an ion-permselective film to block the polysulfides anions by Coulombic repulsion. Furthermore, the graphene sheets can help to stabilize the polyelectrolytes film and greatly reduce the inner resistance of the electrode by changing the transport of the electrons from a "point-to-point" mode to a more effective "plane-to-point'' mode. On the basis of the synergistic effect of the PEMs and graphene sheets, the fabricated composite electrode exhibits very stable cycling stability for over 200 cycles at 1 A g(-1), along with a high average Coulombic efficiency of 99%. With the advantages of rapid and controllable fabrication of the LBL coating film, the multifunctional architecture developed in this study should inspire the design of other lithium-sulfur cathodes with unique physical and chemical properties.

Exposure to space radiation of high-performance infrared multilayer filters and materials technology experiments (A0056)

NASA Technical Reports Server (NTRS)

Seeley, J. S.; Hunneman, R.; Whatley, A.; Lipscombe, D. R.

1984-01-01

Infrared multilayer interface filter which were used in satellite radiometers were examined. The ability of the filters to withstand the space environment in these applications is critical. An experiment on the LDEF subjects the filters to authoritative spectral measurements following space exposure to ascertain their suitability for spacecraft use and to permit an understanding of degradation mechanisms. The understanding of the effects of prolonged space exposure on spacecraft materials, surface finishes, and adhesive systems is important to the spacecraft designer. Materials technology experiments and experiment on infrared multilayer filters are discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Hyun-Cheol; Zhou, Jie E.; Maurya, Deepam

Multilayer ceramic capacitors (MLCC) are widely used in consumer electronics. In this paper, we provide a transformative method for achieving high dielectric response and tunability over a wide temperature range through design of compositionally graded multilayer (CGML) architecture. Compositionally graded MLCCs were found to exhibit enhanced dielectric tunability (70%) along with small dielectric losses (<2.5%) over the required temperature ranges specified in the standard industrial classifications. The compositional grading resulted in generation of internal bias field which enhanced the tunability due to increased nonlinearity. The electric field tunability of MLCCs provides an important avenue for design of miniature filters andmore » power converters.« less

Thermal properties of composite materials : effective conductivity tensor and edge effects

NASA Astrophysics Data System (ADS)

Matine, A.; Boyard, N.; Cartraud, P.; Legrain, G.; Jarny, Y.

2012-11-01

The homogenization theory is a powerful approach to determine the effective thermal conductivity tensor of heterogeneous materials such as composites, including thermoset matrix and fibres. Once the effective properties are calculated, they can be used to solve a heat conduction problem on the composite structure at the macroscopic scale. This approach leads to good approximations of both the heat flux and temperature in the interior zone of the structure, however edge effects occur in the vicinity of the domain boundaries. In this paper, following the approach proposed in [10] for elasticity, it is shown how these edge effects can be corrected. Thus an additional asymptotic expansion is introduced, which plays the role of a edge effect term. This expansion tends to zero far from the boundary, and is assumed to decrease exponentially. Moreover, the length of the edge effect region can be determined from the solution of an eigenvalue problem. Numerical examples are considered for a standard multilayered material. The homogenized solutions computed with a finite element software, and corrected with the edge effect terms, are compared to a heterogeneous finite element solution at the microscopic scale. The influences of the thermal contrast and scale factor are illustrated for different kind of boundary conditions.

Raman spectroscopy of graphene-based materials and its applications in related devices.

PubMed

Wu, Jiang-Bin; Lin, Miao-Ling; Cong, Xin; Liu, He-Nan; Tan, Ping-Heng

2018-03-05

Graphene-based materials exhibit remarkable electronic, optical, and mechanical properties, which has resulted in both high scientific interest and huge potential for a variety of applications. Furthermore, the family of graphene-based materials is growing because of developments in preparation methods. Raman spectroscopy is a versatile tool to identify and characterize the chemical and physical properties of these materials, both at the laboratory and mass-production scale. This technique is so important that most of the papers published concerning these materials contain at least one Raman spectrum. Thus, here, we systematically review the developments in Raman spectroscopy of graphene-based materials from both fundamental research and practical (i.e., device applications) perspectives. We describe the essential Raman scattering processes of the entire first- and second-order modes in intrinsic graphene. Furthermore, the shear, layer-breathing, G and 2D modes of multilayer graphene with different stacking orders are discussed. Techniques to determine the number of graphene layers, to probe resonance Raman spectra of monolayer and multilayer graphenes and to obtain Raman images of graphene-based materials are also presented. The extensive capabilities of Raman spectroscopy for the investigation of the fundamental properties of graphene under external perturbations are described, which have also been extended to other graphene-based materials, such as graphene quantum dots, carbon dots, graphene oxide, nanoribbons, chemical vapor deposition-grown and SiC epitaxially grown graphene flakes, composites, and graphene-based van der Waals heterostructures. These fundamental properties have been used to probe the states, effects, and mechanisms of graphene materials present in the related heterostructures and devices. We hope that this review will be beneficial in all the aspects of graphene investigations, from basic research to material synthesis and device applications.

Ignitable heterogeneous stratified structure for the propagation of an internal exothermic chemical reaction along an expanding wavefront and method of making same

DOEpatents

Barbee, T.W. Jr.; Weihs, T.

1996-07-23

A multilayer structure has a selectable, (1) propagating reaction front velocity V, (2) reaction initiation temperature attained by application of external energy, and (3) amount of energy delivered by a reaction of alternating unreacted layers of the multilayer structure. Because V is selectable and controllable, a variety of different applications for the multilayer structures are possible, including but not limited to their use as igniters, in joining applications, in fabrication of new materials, as smart materials and in medical applications and devices. The multilayer structure has a period D, and an energy release rate constant K. Two or more alternating unreacted layers are made of different materials and separated by reacted zones. The period D is equal to a sum of the widths of each single alternating reaction layer of a particular material, and also includes a sum of reacted zone widths, t{sub i}, in the period D. The multilayer structure has a selectable propagating reaction front velocity V, where V=K(1/D{sup n}){times}[1-(t{sub i}/D)] and n is about 0.8 to 1.2. 8 figs.

Ignitable heterogeneous stratified structure for the propagation of an internal exothermic chemical reaction along an expanding wavefront and method of making same

DOEpatents

Barbee, Jr., Troy W.; Weihs, Timothy

1996-01-01

A multilayer structure has a selectable, (i) propagating reaction front velocity V, (ii) reaction initiation temperature attained by application of external energy and (iii) amount of energy delivered by a reaction of alternating unreacted layers of the multilayer structure. Because V is selectable and controllable, a variety of different applications for the multilayer structures are possible, including but not limited to their use as ignitors, in joining applications, in fabrication of new materials, as smart materials and in medical applications and devices. The multilayer structure has a period D, and an energy release rate constant K. Two or more alternating unreacted layers are made of different materials and separated by reacted zones. The period D is equal to a sum of the widths of each single alternating reaction layer of a particular material, and also includes a sum of reacted zone widths, t.sub.i, in the period D. The multilayer structure has a selectable propagating reaction front velocity V, where V=K(1/D.sup.n).times.[1-(t.sub.i /D)] and n is about 0.8 to 1.2.

Dehomogenized Elastic Properties of Heterogeneous Layered Materials in AFM Indentation Experiments.

PubMed

Lee, Jia-Jye; Rao, Satish; Kaushik, Gaurav; Azeloglu, Evren U; Costa, Kevin D

2018-06-05

Atomic force microscopy (AFM) is used to study mechanical properties of biological materials at submicron length scales. However, such samples are often structurally heterogeneous even at the local level, with different regions having distinct mechanical properties. Physical or chemical disruption can isolate individual structural elements but may alter the properties being measured. Therefore, to determine the micromechanical properties of intact heterogeneous multilayered samples indented by AFM, we propose the Hybrid Eshelby Decomposition (HED) analysis, which combines a modified homogenization theory and finite element modeling to extract layer-specific elastic moduli of composite structures from single indentations, utilizing knowledge of the component distribution to achieve solution uniqueness. Using finite element model-simulated indentation of layered samples with micron-scale thickness dimensions, biologically relevant elastic properties for incompressible soft tissues, and layer-specific heterogeneity of an order of magnitude or less, HED analysis recovered the prescribed modulus values typically within 10% error. Experimental validation using bilayer spin-coated polydimethylsiloxane samples also yielded self-consistent layer-specific modulus values whether arranged as stiff layer on soft substrate or soft layer on stiff substrate. We further examined a biophysical application by characterizing layer-specific microelastic properties of full-thickness mouse aortic wall tissue, demonstrating that the HED-extracted modulus of the tunica media was more than fivefold stiffer than the intima and not significantly different from direct indentation of exposed media tissue. Our results show that the elastic properties of surface and subsurface layers of microscale synthetic and biological samples can be simultaneously extracted from the composite material response to AFM indentation. HED analysis offers a robust approach to studying regional micromechanics of heterogeneous multilayered samples without destructively separating individual components before testing. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Charge carrier transport in defective reduced graphene oxide as quantum dots and nanoplatelets in multilayer films

NASA Astrophysics Data System (ADS)

Jimenez, Mawin J. M.; Oliveira, Rafael F.; Almeida, Tiago P.; Hensel Ferreira, Rafael C.; Bufon, Carlos Cesar B.; Rodrigues, Varlei; Pereira-da-Silva, Marcelo A.; Gobbi, Ângelo L.; Piazzetta, Maria H. O.; Riul, Antonio, Jr.

2017-12-01

Graphene is a breakthrough 2D material due to its unique mechanical, electrical, and thermal properties, with considerable responsiveness in real applications. However, the coverage of large areas with pristine graphene is a challenge and graphene derivatives have been alternatively exploited to produce hybrid and composite materials that allow for new developments, considering also the handling of large areas using distinct methodologies. For electronic applications there is significant interest in the investigation of the electrical properties of graphene derivatives and related composites to determine whether the characteristic 2D charge transport of pristine graphene is preserved. Here, we report a systematic study of the charge transport mechanisms of reduced graphene oxide chemically functionalized with sodium polystyrene sulfonate (PSS), named as GPSS. GPSS was produced either as quantum dots (QDs) or nanoplatelets (NPLs), being further nanostructured with poly(diallyldimethylammonium chloride) through the layer-by-layer (LbL) assembly to produce graphene nanocomposites with molecular level control. Current-voltage (I-V) measurements indicated a meticulous growth of the LbL nanostructures onto gold interdigitated electrodes (IDEs), with a space-charge-limited current dominated by a Mott-variable range hopping mechanism. A 2D intra-planar conduction within the GPSS nanostructure was observed, which resulted in effective charge carrier mobility (μ) of 4.7 cm2 V-1 s-1 for the QDs and 34.7 cm2 V-1 s-1 for the NPLs. The LbL assemblies together with the dimension of the materials (QDs or NPLs) were favorably used for the fine tuning and control of the charge carrier mobility inside the LbL nanostructures. Such 2D charge conduction mechanism and high μ values inside an interlocked multilayered assembly containing graphene-based nanocomposites are of great interest for organic devices and functionalization of interfaces.

Multilayer Coextrusion of Polymer Composites to Develop Organic Capacitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mondy, L.; Mrozek, R.; Rao, R.

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

Multilayer Coextrusion of Polymer Composites to Develop Organic Capacitors

DOE PAGES

Mondy, L.; Mrozek, R.; Rao, 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 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

A unique set of micromechanics equations for high temperature metal matrix composites

NASA Technical Reports Server (NTRS)

Hopkins, D. A.; Chamis, C. C.

1985-01-01

A unique set of micromechanic equations is presented for high temperature metal matrix composites. The set includes expressions to predict mechanical properties, thermal properties and constituent microstresses for the unidirectional fiber reinforced ply. The equations are derived based on a mechanics of materials formulation assuming a square array unit cell model of a single fiber, surrounding matrix and an interphase to account for the chemical reaction which commonly occurs between fiber and matrix. A three-dimensional finite element analysis was used to perform a preliminary validation of the equations. Excellent agreement between properties predicted using the micromechanics equations and properties simulated by the finite element analyses are demonstrated. Implementation of the micromechanics equations as part of an integrated computational capability for nonlinear structural analysis of high temperature multilayered fiber composites is illustrated.

Preparation, characterization, and infrared emissivity property of optically active polyurethane/TiO{sub 2}/SiO{sub 2} multilayered microspheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang Yong; Zhou Yuming, E-mail: ymzhou@seu.edu.cn; Ge Jianhua

Optically active polyurethane/titania/silica (LPU/TiO{sub 2}/SiO{sub 2}) multilayered core-shell composite microspheres were prepared by the combination of titania deposition on the surface of silica spheres and subsequent polymer grafting. LPU/TiO{sub 2}/SiO{sub 2} was characterized by FT-IR, UV-vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), SEM and TEM, and the infrared emissivity value (8-14 {mu}m) was investigated in addition. The results indicated that titania and polyurethane had been successfully coated onto the surfaces of silica microspheres. LPU/TiO{sub 2}/SiO{sub 2} exhibited clearly multilayered core-shell construction. The infrared emissivity values reduced along with the increase of covering layers thus provedmore » that the interfacial interactions had direct influence on the infrared emissivity. Besides, LPU/TiO{sub 2}/SiO{sub 2} multilayered microspheres based on the optically active polyurethane took advantages of the orderly secondary structure and strengthened interfacial synergistic actions. Consequently, it possessed the lowest infrared emissivity value. - Graphical Abstract: Optically active polyurethane/titania/silica (LPU/TiO{sub 2}/SiO{sub 2}) multilayered core-shell composite microspheres were prepared by the combination of titania deposition on the surface of silica spheres and subsequent polymer grafting. Highlights: > Optically active polyurethane based on tyrosine was used for the modification of nanoparticles. > LPU/TiO{sub 2}/SiO{sub 2} multilayered core-shell microspheres were prepared and characterized. > Interfacial interactions and secondary structure affected the infrared emissivity of composite.« less

Investigation of Insulation Materials for Future Radioisotope Power Systems (RPS)

NASA Technical Reports Server (NTRS)

Cornell, Peggy A.; Hurwitz, Frances I.; Ellis, David L.; Schmitz, Paul C.

2013-01-01

NASA's Radioisotope Power System (RPS) Technology Advancement Project is developing next generation high temperature insulation materials that directly benefit thermal management and improve performance of RPS for future science missions. Preliminary studies on the use of multilayer insulation (MLI) for Stirling convertors used on the Advanced Stirling Radioisotope Generator (ASRG) have shown the potential benefits of MLI for space vacuum applications in reducing generator size and increasing specific power (W/kg) as compared to the baseline Microtherm HT (Microtherm, Inc.) insulation. Further studies are currently being conducted at NASA Glenn Research Center (GRC) on candidate MLI foils and aerogel composite spacers. This paper presents the method of testing of foils and spacers and experimental results to date.

Investigation of Insulation Materials for Future Radioisotope Power Systems

NASA Technical Reports Server (NTRS)

Cornell, Peggy A.; Hurwitz, Frances I.; Ellis, David L.; Schmitz, Paul C.

2013-01-01

NASA's Radioisotope Power Systems (RPS) Technology Advancement Project is developing next generation high-temperature insulation materials that directly benefit thermal management and improve performance of RPS for future science missions. Preliminary studies on the use of multilayer insulation (MLI) for Stirling convertors used on the Advanced Stirling Radioisotope Generator (ASRG) have shown the potential benefits of MLI for space vacuum applications in reducing generator size and increasing specific power (W/kg) as compared to the baseline Microtherm HT (Microtherm, Inc.) insulation. Further studies are currently being conducted at NASA Glenn Research Center on candidate MLI foils and aerogel composite spacers. This paper presents the method of testing of foils and spacers and experimental results to date.

A method to optimize the shield compact and lightweight combining the structure with components together by genetic algorithm and MCNP code.

PubMed

Cai, Yao; Hu, Huasi; Pan, Ziheng; Hu, Guang; Zhang, Tao

2018-05-17

To optimize the shield for neutrons and gamma rays compact and lightweight, a method combining the structure and components together was established employing genetic algorithms and MCNP code. As a typical case, the fission energy spectrum of 235 U which mixed neutrons and gamma rays was adopted in this study. Six types of materials were presented and optimized by the method. Spherical geometry was adopted in the optimization after checking the geometry effect. Simulations have made to verify the reliability of the optimization method and the efficiency of the optimized materials. To compare the materials visually and conveniently, the volume and weight needed to build a shield are employed. The results showed that, the composite multilayer material has the best performance. Copyright © 2018 Elsevier Ltd. All rights reserved.

Study of multilayer polymer materials after ionization treatment

NASA Astrophysics Data System (ADS)

Tarasyuk, V. T.; Semkina, A. A.; Solovyeva, V. I.; Fedotova, D. D.; Strokova, N. E.; Malenko, D. M.; Baranov, O. V.; Bakumenko, A. V.; Puchkov, S. N.; Prokopenko, A. V.

2017-12-01

Electron-beam technologies of food products processing involves the use of modern packaging materials in form of polymer films of different composition. The objective of the research is to study the impact of accelerated electrons on the structure of the polymeric packaging materials used for storage of agricultural products. It was investigated radiation exposure on film material PE/PA (80/20) with a thickness of 80 mkm. This film used for storage of vegetables and fruits and has the necessary indicators for gas and vapor permeability. Electron beam treatment of the films was performed on a compact radiation sterilization installation with local bio-protection with electron energy of 5 MeV. A polymer films were irradiated with doses from 1 to 10 kGy. Changing the structure of the film composition was monitored by IR spectrometry. As a result of irradiation by accelerated electrons with doses up to 18 kGy is established that the polymer film is modification of the polymeric material in the form of a partial degradation with subsequent intra-molecular crosslinking. This improves the physico-mechanical properties in the transverse direction, and such film can be used for food packaging before electron-beam treatment.

Residual stress effects on the impact resistance and strength of fiber composites

NASA Technical Reports Server (NTRS)

Chamis, C. C.

1973-01-01

Equations have been derived to predict degradation effects of microresidual stresses on impact resistance of unidirectional fiber composites. Equations also predict lamination residual stresses in multilayered angle ply composites.

Electrically controlled band gap and topological phase transition in two-dimensional multilayer germanane

NASA Astrophysics Data System (ADS)

Qi, Jingshan; Li, Xiao; Qian, Xiaofeng

2016-06-01

Electrically controlled band gap and topological electronic states are important for the next-generation topological quantum devices. In this letter, we study the electric field control of band gap and topological phase transitions in multilayer germanane. We find that although the monolayer and multilayer germananes are normal insulators, a vertical electric field can significantly reduce the band gap of multilayer germananes owing to the giant Stark effect. The decrease of band gap eventually leads to band inversion, transforming them into topological insulators with nontrivial Z2 invariant. The electrically controlled topological phase transition in multilayer germananes provides a potential route to manipulate topologically protected edge states and design topological quantum devices. This strategy should be generally applicable to a broad range of materials, including other two-dimensional materials and ultrathin films with controlled growth.

Indentation-derived elastic modulus of multilayer thin films: Effect of unloading induced plasticity

DOE PAGES

Jamison, Ryan Dale; Shen, Yu -Lin

2015-08-13

Nanoindentation is useful for evaluating the mechanical properties, such as elastic modulus, of multilayer thin film materials. A fundamental assumption in the derivation of the elastic modulus from nanoindentation is that the unloading process is purely elastic. In this work, the validity of elastic assumption as it applies to multilayer thin films is studied using the finite element method. The elastic modulus and hardness from the model system are compared to experimental results to show validity of the model. Plastic strain is shown to increase in the multilayer system during the unloading process. Additionally, the indentation-derived modulus of a monolayermore » material shows no dependence on unloading plasticity while the modulus of the multilayer system is dependent on unloading-induced plasticity. Lastly, the cyclic behavior of the multilayer thin film is studied in relation to the influence of unloading-induced plasticity. Furthermore, it is found that several cycles are required to minimize unloading-induced plasticity.« less

Modification of carbon composites by nanoceramic compounds

NASA Astrophysics Data System (ADS)

Stoch, A.; Jastrzebski, W.; Długoń, E.; Stoch, G. J.; Błażewicz, S.; Adamczyk, A.; Tatarzyńska, K.

2005-06-01

Carbon-carbon composites (C/C) exhibit excellent high-temperature mechanical properties but their air oxidation limits their use at temperatures above 500 °C to inert atmosphere. Variety of coatings has been used to protect C/C composites from oxidation. In this work C/C composite substrates were covered with ceramic multilayer coats by electrophoretic deposition from ceramic sols such as silica sol, alumina sol and silica-lumina sol. Sol particles were of nano-sized dimensions. Deposited coats were annealed at 900-1500 °C. Oxidation tests at 600 °C reveal that the best protection of C/C composite against oxidation gives the multilayer coat formed by three or four electrophoretic depositions. The phase composition in the final annealed layers was analyzed by Infrared spectroscopy (FTIR) and by X-ray diffraction analysis (XRD). Morphology and chemical composition was observed using Scanning electron microscopy (SEM) with energy dispersive X-ray microanalysis (EDS).

SiO2/TiO2/Ag multilayered microspheres: Preparation, characterization, and enhanced infrared radiation property

NASA Astrophysics Data System (ADS)

Ye, Xiaoyun; Cai, Shuguang; Zheng, Chan; Xiao, Xueqing; Hua, Nengbin; Huang, Yanyi

2015-08-01

SiO2/TiO2/Ag core-shell multilayered microspheres were successfully synthesized by the combination of anatase of TiO2 modification on the surfaces of SiO2 spheres and subsequent Ag nanoparticles deposition and Ag shell growth with face-centered cubic (fcc) Ag. The composites were characterized by TEM, FT-IR, UV-vis, Raman spectroscopy and XRD, respectively. The infrared emissivity values during 8-14 μm wavelengths of the composites were measured. The results revealed that TiO2 thin layers with the thickness of ∼10 nm were coated onto the SiO2 spheres of ∼220 nm in diameter. The thickness of the TiO2 layers was controlled by varying the amount of TBOT precursor. Homogeneous Ag nanoparticles of ∼20 nm in size were successfully deposited by ultrasound on the surfaces of SiO2/TiO2 composites, followed by complete covering of Ag shell. The infrared emissivity value of the SiO2/TiO2 composites was decreased than that of pure SiO2. Moreover, the introduction of the Ag brought the remarkably lower infrared emissivity value of the SiO2/TiO2/Ag multilayered microspheres with the lowest value down to 0.424. Strong chemical effects in the interface of SiO2/TiO2 core-shell composites and high reflection performance of the metal Ag are two decisive factors for the improved infrared radiation performance of the SiO2/TiO2/Ag multilayered microspheres.

Thin film photovoltaic device

DOEpatents

Catalano, Anthony W.; Bhushan, Manjul

1982-01-01

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids.

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.

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.

Preparation of multilayered nanocrystalline thin films with composition-modulated interfaces

NASA Astrophysics Data System (ADS)

Biro, D.; Barna, P. B.; Székely, L.; Geszti, O.; Hattori, T.; Devenyi, A.

2008-06-01

The properties of multilayer thin film structures depend on the morphology and structure of interfaces. A broad interface, in which the composition is varying, can enhance, e.g., the hardness of multilayer thin films. In the present experiments multilayers of TiAlN and CrN as well as TiAlN, CrN and MoS 2 were studied by using unbalanced magnetron sputter sources. The sputter sources were arranged side by side on an arc. This arrangement permits development of a transition zone between the layers, where the composition changes continuously. The multilayer system was deposited by one-fold oscillating movement of substrates in front of sputter sources. Thicknesses of layers could be changed both by oscillation frequency and by the power applied to sputter sources. Ti/Al: 50/50 at%, pure chromium and MoS 2 targets were used in the sputter sources. The depositions were performed in an Ar-N 2 mixture at 0.22 Pa working pressure. The sputtering power of the TiAl source was feed-back adjusted in fuzzy-logic mode in order to avoid fluctuation of the TiAl target sputter rate due to poisoning of the target surface. Structure characterization of films deposited on <1 0 0> Si wafers covered by thermally grown SiO 2 was performed by cross-sectional transmission electron microscopy. At first a 100 nm thick Cr base layer was deposited on the substrate to improve adhesion, which was followed by a CrN transition layer. The CrN transition layer was followed by a 100 nm thick TiAlN/CrN multilayer system. The TiAlN/CrN/MoS 2 multilayer system was deposited on the surface of this underlayer system. The underlayer systems Cr, CrN and TiAlN/CrN were crystalline with columnar structure according to the morphology of zone T of the structure zone models. The column boundaries contained segregated phases showing up in the under-focused TEM images. The surface of the underlayer system was wavy due to dome-shaped columns. The nanometer-scaled TiAlN/CrN/MoS 2 multilayer system followed this waviness. Crystallinity of the TiAlN and CrN layers in the multilayer system decreases with increasing thickness of the MoS 2 layer.

High Precision Grids for Neutron, Hard X-Ray, and Gamma-Ray Imaging Systems

NASA Technical Reports Server (NTRS)

Campbell, Jonathan W. (Inventor)

2002-01-01

Fourier telescopes permit observations over a very broad band of energy. They generally include synthetic spatial filtering structures, known as multilayer grids or grid pairs consisting of alternate layers of absorbing and transparent materials depending on whether neutrons or photons are being imaged. For hard x-rays and gamma rays high (absorbing) and low (transparent) atomic number elements, termed high-Z and low-Z materials may be used. Fabrication of these multilayer grid structures is not without its difficulties. Herein the alternate layers of the higher material and the lower material are inserted in a polyhedron, transparent to photons of interest, through an open face of the polyhedron. The inserted layers are then uniformly compressed to form a multilayer grid.

Multilayer Pressure Vessel Materials Testing and Analysis. Phase 1

NASA Technical Reports Server (NTRS)

Cardinal, Joseph W.; Popelar, Carl F.; Page, Richard A.

2014-01-01

To provide NASA a comprehensive suite of materials strength, fracture toughness and crack growth rate test results for use in remaining life calculations for aging multilayer pressure vessels, Southwest Research Institute (R) (SwRI) was contracted in two phases to obtain relevant material property data from a representative vessel. This report describes Phase 1 of this effort which includes a preliminary material property assessment as well as a fractographic, fracture mechanics and fatigue crack growth analyses of an induced flaw in the outer shell of a representative multilayer vessel that was subjected to cyclic pressure test. SwRI performed this Phase 1 effort under contract to the Digital Wave Corporation in support of their contract to Jacobs ATOM for the NASA Ames Research Center.

Delamination micromechanics analysis

NASA Technical Reports Server (NTRS)

Adams, D. F.; Mahishi, J. M.

1985-01-01

A three-dimensional finite element analysis was developed which includes elastoplastic, orthotropic material response, and fracture initiation and propagation. Energy absorption due to physical failure processes characteristic of the heterogeneous and anisotropic nature of composite materials is modeled. A local energy release rate in the presence of plasticity was defined and used as a criterion to predict the onset and growth of cracks in both micromechanics and macromechanics analyses. This crack growth simulation technique is based upon a virtual crack extension method. A three-dimensional finite element micromechanics model is used to study the effects of broken fibers, cracked matrix and fiber-matrix debond on the fracture toughness of the unidirectional composite. The energy release rates at the onset of unstable crack growth in the micromechanics analyses are used as critical energy release rates in the macromechanics analysis. This integrated micromechanical and macromechanical fracture criterion is shown to be very effective in predicting the onset and growth of cracks in general multilayered composite laminates by applying the criterion to a single-edge notched graphite/epoxy laminate subjected to implane tension normal to the notch.

An Electromagnetic/Capacitive Composite Sensor for Testing of Thermal Barrier Coatings

PubMed Central

Ren, Yuan; Pan, Mengchun; Chen, Dixiang; Tian, Wugang

2018-01-01

Thermal barrier coatings (TBCs) can significantly reduce the operating temperature of the aeroengine turbine blade substrate, and their testing technology is very urgently demanded. Due to their complex multi-layer structure, it is hard to evaluate TBCs with a single function sensor. In this paper, an electromagnetic/capacitive composite sensor is proposed for the testing of thermal barrier coatings. The dielectric material is tested with planar capacitor, and the metallic material is tested with electromagnetic coils. Then, the comprehensive test and evaluation of thermal barrier coating system can be realized. The sensor is optimized by means of theoretical and simulation analysis, and the interaction between the planar capacitor and the electromagnetic coil is studied. The experimental system is built based on an impedance analyser and multiplex unit to evaluate the performance of the composite sensor. The transimpedances and capacitances are measured under different coating parameters, such as thickness and permittivity of top coating as well as bond layer conductivity. The experimental results agree with the simulation analysis, and the feasibility of the sensor is proved. PMID:29783746

Ultra-thin multilayer capacitors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renk, Timothy Jerome; Monson, Todd C.

2009-06-01

The fabrication of ultra-thin lanthanum-doped lead zirconium titanate (PLZT) multilayer ceramic capacitors (MLCCs) using a high-power pulsed ion beam was studied. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The goal of this work was to increase the energy density of ceramic capacitors through the formation of a multilayer device with excellent materials properties, dielectric constant, and standoff voltage. For successful device construction, there are a number of challenging requirements including achieving correct stoichiometric and crystallographic composition of the deposited PLZT, as well as the creation of a defect free homogenous film. This report detailsmore » some success in satisfying these requirements, although 900 C temperatures were necessary for PLZT perovskite phase formation. These temperatures were applied to a previously deposited multi-layer film which was then post-annealed to this temperature. The film exhibited mechanical distress attributable to differences in the coefficient of thermal expansion (CTE) of the various layers. This caused significant defects in the deposited films that led to shorts across devices. A follow-on single layer deposition without post-anneal produced smooth layers with good interface behavior, but without the perovskite phase formation. These issues will need to be addressed in order for ion beam deposited MLCCs to become a viable technology. It is possible that future in-situ heating during deposition may address both the CTE issue, and result in lowered processing temperatures, which in turn could raise the probability of successful MLCC formation.« less

RBS Depth Profiling Analysis of (Ti, Al)N/MoN and CrN/MoN Multilayers.

PubMed

Han, Bin; Wang, Zesong; Devi, Neena; Kondamareddy, K K; Wang, Zhenguo; Li, Na; Zuo, Wenbin; Fu, Dejun; Liu, Chuansheng

2017-12-01

(Ti, Al)N/MoN and CrN/MoN multilayered films were synthesized on Si (100) surface by multi-cathodic arc ion plating system with various bilayer periods. The elemental composition and depth profiling of the films were investigated by Rutherford backscattering spectroscopy (RBS) using 2.42 and 1.52 MeV Li 2+ ion beams and different incident angles (0°, 15°, 37°, and 53°). The microstructures of (Ti, Al)N/MoN multilayered films were evaluated by X-ray diffraction. The multilayer periods and thickness of the multilayered films were characterized by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) and then compared with RBS results.

Robust Guar Gum/Cellulose Nanofibrils Multilayer Films with Good Barrier Properties.

PubMed

Dai, Lei; Long, Zhu; Chen, Jie; An, Xingye; Cheng, Dong; Khan, Avik; Ni, Yonghao

2017-02-15

The pursuit of sustainable functional materials requires development of materials based on renewable resources and efficient fabrication methods. Hereby, we fabricated all-polysaccharides multilayer films using cationic guar gum (CGG) and anionic cellulose nanofibrils (i.e., TEMPO-oxidized cellulose nanofibrils, TOCNs) through a layer-by-layer casting method. This technique is based on alternate depositions of oppositely charged water-based CGG and TOCNs onto laminated films. The resultant polyelectrolyte multilayer films were transparent, ductile, and strong. More importantly, the self-standing films exhibited excellent gas (water vapor and oxygen) and oil barrier performances. Another outstanding feature of these resultant films was their resistance to various organic solvents including methanol, acetone, N,N-dimethylacetamide (DMAc) and tetrahydrofuran (THF). The proposed film fabrication process is environmentally benign, cost-effective, and easy to scale-up. The developed CGG/TOCNs multilayer films can be used as a renewable material for industrial applications such as packaging.

Preparation and analysis of multilayer composites based on polyelectrolyte complexes

NASA Astrophysics Data System (ADS)

Petrova, V. A.; Orekhov, A. S.; Chernyakov, D. D.; Baklagina, Yu. G.; Romanov, D. P.; Kononova, S. V.; Volod'ko, A. V.; Ermak, I. M.; Klechkovskaya, V. V.; Skorik, Yu. A.

2016-11-01

A method for preparing multilayer film composites based on chitosan has been developed by the example of polymer pairs: chitosan-hyaluronic acid, chitosan-alginic acid, and chitosan-carrageenan. The structure of the composite films is characterized by X-ray diffractometry and scanning electron microscopy. It is shown that the deposition of a solution of hyaluronic acid, alginic acid, or carrageenan on a chitosan gel film leads to the formation of a polyelectrolyte complex layer at the interface, which is accompanied by the ordering of chitosan chains in the surface region; the microstructure of this layer depends on the nature of contacting polymer pairs.

Synthesis of ‘reactive’ and covalent polymeric multilayer coatings with durable superoleophobic and superoleophilic properties under water† †Electronic supplementary information (ESI) available: Fig. S1–S15 accounting the growth of NC with and without the LbL deposition process, detailed comparisons of the multilayers of BPEI and NC, the change in the underwater oil-wettability with increasing deposition cycles of NC, the change in the optical transparency of the multilayers under water, the underwater oil-wettability of various model oils on post-modified multilayers of NC, bouncing of oil droplets underwater, the change in adhesive interactions with LbL deposition of NC, beading and wetting of oil droplets on post-modified multilayers under water, the effect of heating, freezing, and chemical and physical insults on the oil-wettability of the multilayers under water, LbL coating of various substrates, the guided transfer of oil droplets under water and the cleaning of oil using superoleophilic cotton under water. See DOI: 10.1039/c7sc01055a Click here for additional data file.

PubMed Central

Parbat, Dibyangana

2017-01-01

Bioinspired underwater super-oil-wettability (superoleophilic/superoleophobic) properties are emerging as a potential avenue for developing smart materials for addressing issues related to healthcare, environment, energy, etc. However, the inherent poor durability of the materials that are mostly developed using polymeric hydrogel, metal oxide coatings and electrostatic multilayers often challenges the application of these wettability properties in practical scenarios. Here, ‘amine-reactive’ polymeric multilayers of nano-complex were developed to fabricate ‘internal’ underwater superoleophobic/superoleophilic coatings with impeccable physical/chemical durability. This allows the super-wetting properties to exist beyond the surface of the material and remain intact even after severe physical damage including erosion of the material and continuous exposure to an artificial-marine environment for more than 80 days. Moreover, this current design allowed for independent revalidation of some key hypotheses with direct experimental demonstrations, and provided a basis to develop highly durable super-oil-wettability properties under water. It is believed that this contemporary study will make a worthwhile contribution on developing multifunctional materials for widespread practical applications by exploiting these super-oil-wetting properties. PMID:28989639

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.

Electrically controlled band gap and topological phase transition in two-dimensional multilayer germanane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qi, Jingshan, E-mail: qijingshan@jsnu.edu.cn, E-mail: feng@tamu.edu; Li, Xiao; Qian, Xiaofeng, E-mail: qijingshan@jsnu.edu.cn, E-mail: feng@tamu.edu

2016-06-20

Electrically controlled band gap and topological electronic states are important for the next-generation topological quantum devices. In this letter, we study the electric field control of band gap and topological phase transitions in multilayer germanane. We find that although the monolayer and multilayer germananes are normal insulators, a vertical electric field can significantly reduce the band gap of multilayer germananes owing to the giant Stark effect. The decrease of band gap eventually leads to band inversion, transforming them into topological insulators with nontrivial Z{sub 2} invariant. The electrically controlled topological phase transition in multilayer germananes provides a potential route tomore » manipulate topologically protected edge states and design topological quantum devices. This strategy should be generally applicable to a broad range of materials, including other two-dimensional materials and ultrathin films with controlled growth.« less

Numerical simulation and experiment on multilayer stagger-split die.

PubMed

Liu, Zhiwei; Li, Mingzhe; Han, Qigang; Yang, Yunfei; Wang, Bolong; Sui, Zhou

2013-05-01

A novel ultra-high pressure device, multilayer stagger-split die, has been constructed based on the principle of "dividing dies before cracking." Multilayer stagger-split die includes an encircling ring and multilayer assemblages, and the mating surfaces of the multilayer assemblages are mutually staggered between adjacent layers. In this paper, we investigated the stressing features of this structure through finite element techniques, and the results were compared with those of the belt type die and single split die. The contrast experiments were also carried out to test the bearing pressure performance of multilayer stagger-split die. It is concluded that the stress distributions are reasonable and the materials are utilized effectively for multilayer stagger-split die. And experiments indicate that the multilayer stagger-split die can bear the greatest pressure.

Structural, mechanical and tribocorrosion behaviour in artificial seawater of CrN/AlN nano-multilayer coatings on F690 steel substrates

NASA Astrophysics Data System (ADS)

Ma, Fuliang; Li, Jinlong; Zeng, Zhixiang; Gao, Yimin

2018-01-01

The CrN monolayer and CrN/AlN nano-multilayer coating were successfully fabricated by reactive magnetron sputtering on F690 steel. The results show that CrN monolayer exhibits a face centered cubic crystalline structure with (111) preferred orientation and CrN/AlN nano-multilayer coating has a (200) preferred orientation. This design of the nano-multilayer can interrupt the continuous growth of columnar crystals making the coating denser. The CrN/AlN nano-multilayer coating has a better wear resistance and corrosion resistance compared with the CrN monolayer coating. The tribocorrosion tests reveal that the evolution of potential and current density of F690 steel and CrN monolayer or CrN/AlN nano-multilayer coating see an opposite trend under the simultaneous action of wear and corrosion, which is attributed to that F690 steel is a non-passive material and PVD coatings is a passive material. The nano-multilayer structure has a good ;Pore Sealing Effect;, and the corrosive solution is difficult to pass through the coating to corrode the substrate.

Trials of flexible pipe in sour service reveal degradation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Maslamani, M.J.

Field trials on flexible pipe offshore Qatar have shown that, under sour conditions, the layered, composite material can suffer severe degradation leading to failure. The failure demonstrates the significant effects of stress level, environmental aggressiveness, and localized hard zones in promoting sulfide stress cracking. Permeability of the sour gas through the composite layer of the flexible pipe resulted in varying degrees of sulfide attack and hydrogen embrittlement, depending on the susceptibility of the multilayered material. In the trials, the material was used as a gas-lift line in a sour-oil field in the Arabian Gulf. Flexible pipes have been used successfullymore » for transporting methanol, benzene, and gas condensates in wet sweet environments at temperatures of up to 80 C. Little or no information, however, has been available as to its corrosion resistance in sour-service wells containing 6% CO{sub 2} with 3% H{sub 2}S partial pressures and at moderate temperatures. The paper discusses an underwater survey to evaluate the damage, visual inspection, mechanical tests, metallographic exam, and trial results.« less

An Overview of SBIR Phase 2 Materials Structures for Extreme Environments

NASA Technical Reports Server (NTRS)

Nguyen, Hung D.; Steele, Gynelle C.

2015-01-01

Technological innovation is the overall focus of NASA's Small Business Innovation Research (SBIR) program. The program invests in the development of innovative concepts and technologies to help NASA's mission directorates address critical research and development needs for agency projects. This report highlights innovative SBIR Phase II projects from 2007-2012 specifically addressing Areas in Materials and Structures for Extreme Environments which is one of six core competencies at NASA Glenn Research Center. There are twenty three technologies featured with emphasis on a wide spectrum of applications such as fine-filament superconductor wire, composite oxide cathode materials, nano-composites, high radiation solar cell, wrapped multilayer insulation, thin aerogel, and much more. Each article in this booklet describes an innovation, technical objective, and highlights NASA commercial and industrial applications. This report serves as an opportunity for NASA personnel including engineers, researchers, and program managers to learn of NASA SBIR's capabilities that might be crosscutting into this technology area. As the result, it would cause collaborations and partnerships between the small companies and NASA Programs and Projects resulting in benefit to both SBIR companies and NASA.

Universal approach for appending double-negative materials to magneto-optics in multilayer structures

NASA Astrophysics Data System (ADS)

Zamani, Mehdi; Eftekhari, Sepideh; Ghanaatshoar, Majid

2018-04-01

We express a general formalism to describe light propagation in multilayers including both left-handed and normal magnetic materials. In this order, we employ propagation and boundary matrices which are applicable to any configuration of media, incident angle of light and orientation of magnetization in each ferromagnetic layer. We calculate the Kerr and Faraday rotation in some given magneto-optical multilayers and show that this universal approach can thoroughly illustrate spectral broadening by the left-handed layers, even in presence of dispersion effect.

Near-infrared radiation curable multilayer coating systems and methods for applying same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowman, Mark P; Verdun, Shelley D; Post, Gordon L

2015-04-28

Multilayer coating systems, methods of applying and related substrates are disclosed. The coating system may comprise a first coating comprising a near-IR absorber, and a second coating deposited on a least a portion of the first coating. Methods of applying a multilayer coating composition to a substrate may comprise applying a first coating comprising a near-IR absorber, applying a second coating over at least a portion of the first coating and curing the coating with near infrared radiation.

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.

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.

Strain and mechanical properties of the VCM multilayer sheet and their composites using the digital speckle correlation method.

PubMed

Zhang, Dehai; Xie, Guizhong; Li, Yanqin; Liu, Jianxiu

2015-09-01

The digital speckle correlation method (DSCM) is introduced to solve the challenging problems in the related geometric measurement. Theoretical calculations of strain are deduced using the DSCM. Corresponding strains along x and y directions are obtained from uniaxial tension experiments and digital speckle measurements, using the VCM nondeep drawing multilayer sheet, the VCM deep-drawing multilayer sheet, clad films, nondeep drawing substrate, and deep-drawing substrate sheet as the targeted experimental objects. The results show that the maximum strains along the x direction of the VCM nondeep drawing multilayer sheet, the VCM deep-drawing multilayer sheet, clad film, nondeep drawing substrate, and deep-drawing substrate sheet are 68.473%, 48.632%, 91.632%, 50.784% and 40.068%, respectively, while the maximum strains along the y direction are -2.657%, -15.381%, 2.826%, -9.780% and -7.783%, respectively. The mechanical properties of the VCM multilayer sheet are between those of the substrate and clad film, while mechanical properties of the VCM deep-drawing multilayer sheet are superior to those of the VCM nondeep drawing multi-layer sheet.

Inkjet Deposition of Layer by Layer Assembled Films

PubMed Central

Andres, Christine M.; Kotov, Nicholas A.

2010-01-01

Layer-by-layer assembly (LBL) can create advanced composites with exceptional properties unavailable by other means, but the laborious deposition process and multiple dipping cycles hamper their utilization in microtechnologies and electronics. Multiple rinse steps provide both structural control and thermodynamic stability to LBL multilayers but they significantly limit their practical applications and contribute significantly to the processing time and waste. Here we demonstrate that by employing inkjet technology one can deliver the necessary quantities of LBL components required for film build-up without excess, eliminating the need for repetitive rinsing steps. This feature differentiates this approach from all other recognized LBL modalities. Using a model system of negatively charged gold nanoparticles and positively charged poly(diallyldimethylammonium) chloride, the material stability, nanoscale control over thickness and particle coverage offered by the inkjet LBL technique are shown to be equal or better than the multilayers made with traditional dipping cycles. The opportunity for fast deposition of complex metallic patterns using a simple inkjet printer was also shown. The additive nature of LBL deposition based on the formation of insoluble nanoparticle-polyelectrolyte complexes of various compositions provides an excellent opportunity for versatile, multi-component, and non-contact patterning for the simple production of stratified patterns that are much needed in advanced devices. PMID:20863114

Implementation of Laminate Theory Into Strain Rate Dependent Micromechanics Analysis of Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.

2000-01-01

A research program is in progress to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to impact loads. Previously, strain rate dependent inelastic constitutive equations developed to model the polymer matrix were implemented into a mechanics of materials based micromechanics method. In the current work, the computation of the effective inelastic strain in the micromechanics model was modified to fully incorporate the Poisson effect. The micromechanics equations were also combined with classical laminate theory to enable the analysis of symmetric multilayered laminates subject to in-plane loading. A quasi-incremental trapezoidal integration method was implemented to integrate the constitutive equations within the laminate theory. Verification studies were conducted using an AS4/PEEK composite using a variety of laminate configurations and strain rates. The predicted results compared well with experimentally obtained values.

Formability of tufted 3-dimensional composite reinforcement

NASA Astrophysics Data System (ADS)

Liu, Ling Shan; Wang, Peng; Legrand, Xavier; Soulat, Damien

2016-10-01

In the aerospace industry, more and more complex preform for composite parts are needed. Traditionally, laminated reinforcement is largely used as the method. The development of tufting technology has now advanced to a stage whereby it can be employed to produce the 3D textile composite reinforcements. Because the tufting technology is user-friendly, in this study, the tufting parameters (tufting density, tufting length, tufting yarn orientations…) are varied, in order to improve the understanding of formability of the tufted 3D fabric during manufacturing, in particular the influence of the tufting yarns, the present work is performed to analyse the preforming behaviours of tufted 3D reinforcement in the hemispherical stamping process. The preforming behaviours are also compared with the ones of the multilayered forming. Interply sliding and winkling phenomenon during forming are fully influenced by tufting yarns on the material draw-in, by the orientations of tufting yarn, …

Fabrication and Characteristics of Al/PTFE Multilayers and Application in Micro-initiator

NASA Astrophysics Data System (ADS)

Zhang, Yuxin; Jiang, Hongchuan; Zhao, Xiaohui; Zhang, Wanli; Li, Yanrong

2017-12-01

In this paper, a micro-initiator was designed and fabricated by integrating Al/PTFE multilayers with a Cu film bridge. The regularity layer structure and interface composition of Al/PTFE multilayers was analysed by transmission electron microscope and X-ray photoelectron spectroscopy, respectively. The heat release reaction in Al/PTFE multilayers can be triggered with reaction temperature of 430 °C, and the overall heat of reaction is 3192 J/g. Al/PTFE multilayers with bilayer thickness of 200 nm was alternately deposited on a Cu film bridge to improve the electric explosion performances. Compared to Cu film bridge, the Al/PTFE/Cu integrated film bridge exhibits improved performances with longer explosion duration time, more violent explosion phenomenon and larger quantities of ejected product particles.

The design of broadband radar absorbing surfaces

NASA Astrophysics Data System (ADS)

Suk, Go H.

1990-09-01

There has been a growing and widespread interest in radar absorbing material technology. As the name implies, radar absorbing materials or RAM's are coatings whose electric and magnetic properties have been selected to allow the absorption of microwave energy at discrete or broadband frequencies. In military applications low radar cross section (RCS) of a vehicle may be required in order to escape detection while a covert mission is being carried on. These requirements have led to the very low observable or stealth technology that reduces the probability of detection of an aircraft. The design of radar absorbing materials is limited by constraints on the allowable volume and weight of the surface coating, and it is difficult to design a broadband radar absorbing structure in limited volume. This thesis investigates the use of lossy dielectric materials of high dielectric permittivity in multilayer composites for the production of low radar cross section (RCS). The analysis is done by computing the plane wave reflection coefficient at the exterior surface of the composite coating by means of a computer program which selects layer parameters which determine low reflection coefficients for electromagnetic radiation under constraint of limited layer thickness as well as maximum frequency bandwidth.

Application of carbide cutting tools with nano-structured multilayer composite coatings for turning austenitic steels, type 16Cr-10NI

NASA Astrophysics Data System (ADS)

Vereschaka, Alexey; Migranov, Mars; Oganyan, Gaik; Sotova, Catherine S.; Batako, Andre

2018-03-01

This paper addresses the challenges of increasing the efficiency of the machining of austenitic stainless steels AISI 321 and S31600 by application of cutting tools with multilayer composite nano-structured coatings. The main mechanical properties and internal structures of the coatings under study (hardness, adhesion strength in the "coating-substrate" system) were investigated, and their chemical compositions were analyzed. The conducted research of tool life and nature of wear of carbide tools with the investigated coatings during turning of the above mentioned steels showed that the application of those coatings increases the tool life by up to 2.5 times. In addition, the use of a cutting tool with coatings allows machining at higher cutting speeds. It was also found that the use of a tool with multilayer composite nano-structured coating (Zr,Nb)N-(Zr,Al,Nb)N ensures better results compared with not only monolithic coating TiN, but also with nano-structured coatings Ti-TiN-(Ti,Al)N and (Zr,Nb)N-(Cr,Zr,Nb,Al)N. The mechanism of failure of the coatings under study was also investigated.

Process for manufacturing multilayer capacitors

DOEpatents

Lauf, Robert J.; Holcombe, Cressie E.; Dykes, Norman L.

1996-01-01

The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation.

Composite Flexible Blanket Insulation

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A. (Inventor); Pitts, William C. (Inventor); Goldstein, Howard E. (Inventor); Sawko, Paul M. (Inventor)

1991-01-01

Composite flexible multilayer insulation systems (MLI) were evaluated for thermal performance and compared with the currently used fibrous silica (baseline) insulation system. The systems described are multilayer insulations consisting of alternating layers of metal foil and scrim ceramic cloth or vacuum metallized polymeric films quilted together using ceramic thread. A silicon carbide thread for use in the quilting and the method of making it are also described. These systems are useful in providing lightweight insulation for a variety of uses, particularly on the surface of aerospace vehicles subject to very high temperatures during flight.

Shock compression response of cold-rolled Ni/Al multilayer composites

DOE PAGES

Specht, Paul E.; Weihs, Timothy P.; Thadhani, Naresh N.

2017-01-06

Uniaxial strain, plate-on-plate impact experiments were performed on cold-rolled Ni/Al multilayer composites and the resulting Hugoniot was determined through time-resolved measurements combined with impedance matching. The experimental Hugoniot agreed with that previously predicted by two dimensional (2D) meso-scale calculations. Additional 2D meso-scale simulations were performed using the same computational method as the prior study to reproduce the experimentally measured free surface velocities and stress profiles. Finally, these simulations accurately replicated the experimental profiles, providing additional validation for the previous computational work.

Sombrero-shaped plasmonic nanoparticles with molecular-level sensitivity and multifunctionality.

PubMed

Wi, Jung-Sub; Barnard, Edward S; Wilson, Robert J; Zhang, Mingliang; Tang, Mary; Brongersma, Mark L; Wang, Shan X

2011-08-23

We demonstrate top-down synthesis of monodisperse plasmonic nanoparticles designed to contain internal Raman hot spots. Our Raman-active nanoparticles are fabricated using nanoimprint lithography and thin-film deposition and are composed of novel internal structures with sublithographic dimensions: a disk-shaped Ag core, a Petri-dish-shaped SiO(2) base whose inner surface is coated with Ag film, and a sub-10 nm scale circular gap between the core and the base. Confocal Raman measurements and electromagnetic simulations show that Raman hot spots appear at the inside perimeter of individual nanoparticles and serve as the source of a 1000-fold improvement of minimum molecular detection level that enables detection of signals from a few molecules near hot spots. A multimodality version of these nanoparticles, which includes the functionality offered by magnetic multilayers, is also demonstrated. These results illustrate the potential of direct fabrication for creating exotic monodisperse nanoparticles, which combine engineered internal nanostructures and multilayer composite materials, for use in nanoparticle-based molecular imaging and detection. © 2011 American Chemical Society

High-temperature properties of joint interface of VPS-tungsten coated CFC

NASA Astrophysics Data System (ADS)

Tamura, S.; Liu, X.; Tokunaga, K.; Tsunekawa, Y.; Okumiya, M.; Noda, N.; Yoshida, N.

2004-08-01

Tungsten coated carbon fiber composite (CFC) is a candidate material for the high heat flux components in fusion reactors. In order to investigate the high-temperature properties at the joint interface of coating, heat load experiments by using electron beam were performed on VPS-tungsten coated CX-2002U samples. After the heat load test for 3.6 ks at 1400 °C, tungsten-rhenium multilayer (diffusion barrier for carbon) at the joint interface of coating was observed clearly. But, at the temperatures above 1600 °C, the multilayer was disappeared and a tungsten carbide layer was formed in the VPS-tungsten coating. At the temperatures below 1800 °C, the thickness of this layer logarithmically increased with increasing its loading time. At 2000 °C, the growth of the tungsten carbide layer was proportional to the square root of loading time. These results indicate that the diffusion barrier for carbon is not expected to suppress the carbide formation at the joint interface of the VPS-tungsten coating above 1600 °C.

Nano-structuring of multi-layer material by single x-ray vortex pulse with femtosecond duration

NASA Astrophysics Data System (ADS)

Kohmura, Yoshiki; Zhakhovsky, Vasily; Takei, Dai; Suzuki, Yoshio; Takeuchi, Akihisa; Inoue, Ichiro; Inubushi, Yuichi; Inogamov, Nail; Ishikawa, Tetsuya; Yabashi, Makina

2018-03-01

A narrow zero-intensity spot arising from an x-ray vortex has huge potential for future applications such as nanoscopy and nanofabrication. We here present an X-ray Free Electron Laser (XFEL) experiment with a focused vortex wavefront which generated high aspect ratio nanoneedles on a Cr/Au multi-layer (ML) specimen. A sharp needle with a typical width and height of 310 and 600 nm was formed with a high occurrence rate at the center of a 7.71 keV x-ray vortex on this ML specimen, respectively. The observed width exceeds the diffraction limit, and the smallest structures ever reported using an intense-XFEL ablation were fabricated. We found that the elemental composition of the nanoneedles shows a significant difference from that of the unaffected area of Cr/Au ML. All these results are well explained by the molecular dynamics simulations, leading to the elucidation of the needle formation mechanism on an ultra-fast timescale.

Electromagnetic characterization of advanced nanostructured materials and multilayer design optimization for metrological and low radar observability applications

NASA Astrophysics Data System (ADS)

Micheli, Davide; Pastore, Roberto; Delfini, Andrea; Giusti, Alfonso; Vricella, Antonio; Santoni, Fabio; Marchetti, Mario; Tolochko, Oleg; Vasilyeva, Ekaterina

2017-05-01

In this work the electromagnetic characterization of composite materials reinforced with carbon and metallic nanoparticles is presented. In particular, the electric permittivity and the magnetic permeability as a function of the frequency are used to evaluate the electromagnetic absorption capability of the nanocomposites. The aim is the study of possible applications in advanced coating able to tune the electromagnetic reflectivity of satellite surfaces in specific frequency ranges, in a special way for those surfaces that for some reason could be exposed to the antenna radiation pattern. In fact, the interference caused by the spurious electromagnetic multipath due to good electric conductive satellite surface components could in turn affect the main radiation lobe of TLC and Telemetry antennas, thus modifying its main propagation directions and finally increasing the microwave channel pathloss. The work reports the analysis of different nanostructured materials in the 2-10 GHz frequency range. The employed nanopowders are of carbon nanotubes, cobalt, argent, titanium, nickel, zinc, copper, iron, boron, bismuth, hafnium, in different weight percentages versus the hosting polymeric matrix. The materials are classified as a function of their electromagnetic losses capability by taking into account of both electric and magnetic properties. The possibility to design multi-layered structures optimized to provide specific microwave response is finally analyzed by the aid of swam intelligence algorithm. This novel technique is in general interesting for metrological purpose and remote sensing purposes, and can be effectively used in aerospace field for frequency selective materials design, in order to reduce the aircraft/spacecraft radar observability at certain frequencies.

A chemically stable PVD multilayer encapsulation for lithium microbatteries

NASA Astrophysics Data System (ADS)

Ribeiro, J. F.; Sousa, R.; Cunha, D. J.; Vieira, E. M. F.; Silva, M. M.; Dupont, L.; Goncalves, L. M.

2015-10-01

A multilayer physical vapour deposition (PVD) thin-film encapsulation method for lithium microbatteries is presented. Lithium microbatteries with a lithium cobalt oxide (LiCoO2) cathode, a lithium phosphorous oxynitride (LiPON) electrolyte and a metallic lithium anode are under development, using PVD deposition techniques. Metallic lithium film is still the most common anode on this battery technology; however, it presents a huge challenge in terms of material encapsulation (lithium reacts with almost any materials deposited on top and almost instantly begins oxidizing in contact with atmosphere). To prove the encapsulation concept and perform all the experiments, lithium films were deposited by thermal evaporation technique on top of a glass substrate, with previously patterned Al/Ti contacts. Three distinct materials, in a multilayer combination, were tested to prevent lithium from reacting with protection materials and atmosphere. These multilayer films were deposited by RF sputtering and were composed of lithium phosphorous oxide (LiPO), LiPON and silicon nitride (Si3N4). To complete the long-term encapsulation after breaking the vacuum, an epoxy was applied on top of the PVD multilayer. In order to evaluate oxidation state of lithium films, the lithium resistance was measured in a four probe setup (cancelling wires/contact resistances) and resistivity calculated, considering physical dimensions. A lithium resistivity of 0.16 Ω μm was maintained for more than a week. This PVD multilayer exonerates the use of chemical vapour deposition (CVD), glove-box chambers and sample manipulation between them, significantly reducing the fabrication cost, since battery and its encapsulation are fabricated in the same PVD chamber.

Advanced materials for multilayer mirrors for extreme ultraviolet solar astronomy.

PubMed

Bogachev, S A; Chkhalo, N I; Kuzin, S V; Pariev, D E; Polkovnikov, V N; Salashchenko, N N; Shestov, S V; Zuev, S Y

2016-03-20

We provide an analysis of contemporary multilayer optics for extreme ultraviolet (EUV) solar astronomy in the wavelength ranges: λ=12.9-13.3  nm, λ=17-21  nm, λ=28-33  nm, and λ=58.4  nm. We found new material pairs, which will make new spaceborne experiments possible due to the high reflection efficiencies, spectral resolution, and long-term stabilities of the proposed multilayer coatings. In the spectral range λ=13  nm, Mo/Be multilayer mirrors were shown to demonstrate a better ratio of reflection efficiency and spectral resolution compared with the commonly used Mo/Si. In the spectral range λ=17-21  nm, a new multilayer structure Al/Si was proposed, which had higher spectral resolution along with comparable reflection efficiency compared with the commonly used Al/Zr multilayer structures. In the spectral range λ=30  nm, the Si/B₄C/Mg/Cr multilayer structure turned out to best obey reflection efficiency and long-term stability. The B₄C and Cr layers prevented mutual diffusion of the Si and Mg layers. For the spectral range λ=58  nm, a new multilayer Mo/Mg-based structure was developed; its reflection efficiency and long-term stability have been analyzed. We also investigated intrinsic stresses inherent for most of the multilayer structures and proposed possibilities for stress elimination.

Cryogenic Insulation System for Soft Vacuum

NASA Technical Reports Server (NTRS)

Augustynowicz, S. D.; Fesmire, J. E.

1999-01-01

The development of a cryogenic insulation system for operation under soft vacuum is presented in this paper. Conventional insulation materials for cryogenic applications can be divided into three levels of thermal performance, in terms of apparent thermal conductivity [k-value in milliwatt per meter-kelvin (mW/m-K)]. System k-values below 0.1 can be achieved for multilayer insulation operating at a vacuum level below 1 x 10(exp -4) torr. For fiberglass or powder operating below 1 x 10(exp -3) torr, k-values of about 2 are obtained. For foam and other materials at ambient pressure, k-values around 30 are typical. New industry and aerospace applications require a versatile, robust, low-cost thermal insulation with performance in the intermediate range. The target for the new composite insulation system is a k-value below 4.8 mW/m-K (R-30) at a soft vacuum level (from 1 to 10 torr) and boundary temperatures of approximately 77 and 293 kelvin (K). Many combinations of radiation shields, spacers, and composite materials were tested from high vacuum to ambient pressure using cryostat boiloff methods. Significant improvement over conventional systems in the soft vacuum range was demonstrated. The new layered composite insulation system was also shown to provide key benefits for high vacuum applications as well.

Multi-layer composite structure covered polytetrafluoroethylene for visible-infrared-radar spectral Compatibility

NASA Astrophysics Data System (ADS)

Qi, Dong; Cheng, Yongzhi; Wang, Xian; Wang, Fang; Li, Bowen; Gong, Rongzhou

2017-12-01

In this paper, a polytetrafluoroethylene (PTFE) top-covered multi-layer composite structure PTFE/H s/(Ge/ZnS)3 (H s represents the surface layer ZnS with various thicknesses) for spectral compatibility is proposed and investigated theoretically and experimentally. A substantial decline of glossiness from over 200 Gs to 74.2 Gs could be realized, due to high roughness and interface reflection of the 800 nm PTFE protection layer. In addition, similar to the structure of H s/(Ge/ZnS)3, the designed structure with a certain color exhibits ultra-low emissivity of average 0.196 at 8-14 µm and highly transparent performance of 96.45% in the radar frequency range of 2-18 GHz. Our design will provide an important reference for the practical applications of the spectral compatible multilayer films.

Polytypism and unexpected strong interlayer coupling in two-dimensional layered ReS2

NASA Astrophysics Data System (ADS)

Qiao, Xiao-Fen; Wu, Jiang-Bin; Zhou, Linwei; Qiao, Jingsi; Shi, Wei; Chen, Tao; Zhang, Xin; Zhang, Jun; Ji, Wei; Tan, Ping-Heng

2016-04-01

Anisotropic two-dimensional (2D) van der Waals (vdW) layered materials, with both scientific interest and application potential, offer one more dimension than isotropic 2D materials to tune their physical properties. Various physical properties of 2D multi-layer materials are modulated by varying their stacking orders owing to significant interlayer vdW coupling. Multilayer rhenium disulfide (ReS2), a representative anisotropic 2D material, was expected to be randomly stacked and lack interlayer coupling. Here, we demonstrate two stable stacking orders, namely isotropic-like (IS) and anisotropic-like (AI) N layer (NL, N > 1) ReS2 are revealed by ultralow- and high-frequency Raman spectroscopy, photoluminescence and first-principles density functional theory calculation. Two interlayer shear modes are observed in AI-NL-ReS2 while only one shear mode appears in IS-NL-ReS2, suggesting anisotropic- and isotropic-like stacking orders in IS- and AI-NL-ReS2, respectively. This explicit difference in the observed frequencies identifies an unexpected strong interlayer coupling in IS- and AI-NL-ReS2. Quantitatively, the force constants of them are found to be around 55-90% of those of multilayer MoS2. The revealed strong interlayer coupling and polytypism in multi-layer ReS2 may stimulate future studies on engineering physical properties of other anisotropic 2D materials by stacking orders.Anisotropic two-dimensional (2D) van der Waals (vdW) layered materials, with both scientific interest and application potential, offer one more dimension than isotropic 2D materials to tune their physical properties. Various physical properties of 2D multi-layer materials are modulated by varying their stacking orders owing to significant interlayer vdW coupling. Multilayer rhenium disulfide (ReS2), a representative anisotropic 2D material, was expected to be randomly stacked and lack interlayer coupling. Here, we demonstrate two stable stacking orders, namely isotropic-like (IS) and anisotropic-like (AI) N layer (NL, N > 1) ReS2 are revealed by ultralow- and high-frequency Raman spectroscopy, photoluminescence and first-principles density functional theory calculation. Two interlayer shear modes are observed in AI-NL-ReS2 while only one shear mode appears in IS-NL-ReS2, suggesting anisotropic- and isotropic-like stacking orders in IS- and AI-NL-ReS2, respectively. This explicit difference in the observed frequencies identifies an unexpected strong interlayer coupling in IS- and AI-NL-ReS2. Quantitatively, the force constants of them are found to be around 55-90% of those of multilayer MoS2. The revealed strong interlayer coupling and polytypism in multi-layer ReS2 may stimulate future studies on engineering physical properties of other anisotropic 2D materials by stacking orders. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01569g

Finite element analysis of multilayer DEAP stack-actuators

NASA Astrophysics Data System (ADS)

Kuhring, Stefan; Uhlenbusch, Dominik; Hoffstadt, Thorben; Maas, Jürgen

2015-04-01

Dielectric elastomers (DE) are thin polymer films belonging to the class of electroactive polymers (EAP). They are coated with compliant and conductive electrodes on each side, which make them performing a relative high amount of deformation with considerable force generation under the influence of an electric field. Because the realization of high electric fields with a limited voltage level requests single layer polymer films to be very thin, novel multilayer actuators are utilized to increase the absolute displacement and force. In case of a multilayer stack-actuator, many actuator films are mechanically stacked in series and electrically connected in parallel. Because there are different ways to design such a stack-actuator, this contribution considers an optimization of some design parameters using the finite element analysis (FEA), whereby the behavior and the actuation of a multilayer dielectric electroactive polymer (DEAP) stack-actuator can be improved. To describe the material behavior, first different material models are compared and necessary material parameters are identified by experiments. Furthermore, a FEA model of a DEAP film is presented, which is expanded to a multilayer DEAP stack-actuator model. Finally, the results of the FEA are discussed and conclusions for design rules of optimized stack-actuators are outlined.

Potential of laser-induced breakdown spectroscopy for discrimination of nano-sized carbon materials. Insights on the optical characterization of graphene

NASA Astrophysics Data System (ADS)

Serrano, J.; Cabalín, L. M.; Moros, J.; Laserna, J. J.

2014-07-01

Since its invention in 2004, graphene has attracted considerable interest worldwide. Advances in the use of graphene in materials science and engineering require important increases in the quality of the final product for integration in photonic and electronic devices. To meet this demand, which will become increasingly strict in the future, analytical techniques capable of differentiating between the starting materials and graphene need to be developed. The interest in the use of laser-induced breakdown spectroscopy (LIBS) for this application rests on the rapid progress experienced by this technology for identification of carbon-based materials of close chemical composition. The potential of LIBS has been explored here by a careful investigation of the spectral properties of both multi-layer and few-layer graphene, graphite and graphene oxide. Results reveal significant differences in the specific optical emission responses of these materials, expressly reflected on the behavior of CN and C2 molecular emissions. These differences result from the particularities of the materials, such as the number of carbon layers and the carbon hybridization in the bonding structure, together with the post-ablation evolution of the concerned plasma plume. In short, this interconnection between ablation and emission events generated from each material allows its characterization and its differentiation from other materials with highly similar chemical composition.

Computational simulation of acoustic fatigue for hot composite structures

NASA Technical Reports Server (NTRS)

Singhal, S. N.; Nagpal, V. K.; Murthy, P. L. N.; Chamis, C. C.

1991-01-01

This paper presents predictive methods/codes for computational simulation of acoustic fatigue resistance of hot composite structures subjected to acoustic excitation emanating from an adjacent vibrating component. Select codes developed over the past two decades at the NASA Lewis Research Center are used. The codes include computation of (1) acoustic noise generated from a vibrating component, (2) degradation in material properties of the composite laminate at use temperature, (3) dynamic response of acoustically excited hot multilayered composite structure, (4) degradation in the first-ply strength of the excited structure due to acoustic loading, and (5) acoustic fatigue resistance of the excited structure, including propulsion environment. Effects of the laminate lay-up and environment on the acoustic fatigue life are evaluated. The results show that, by keeping the angled plies on the outer surface of the laminate, a substantial increase in the acoustic fatigue life is obtained. The effect of environment (temperature and moisure) is to relieve the residual stresses leading to an increase in the acoustic fatigue life of the excited panel.

Computational simulation of acoustic fatigue for hot composite structures

NASA Technical Reports Server (NTRS)

Singhal, Surendra N.; Murthy, Pappu L. N.; Chamis, Christos C.; Nagpal, Vinod K.; Sutjahjo, Edhi

1991-01-01

Predictive methods/computer codes for the computational simulation of acoustic fatigue resistance of hot composite structures subjected to acoustic excitation emanating from an adjacent vibrating component are discussed. Select codes developed over the past two decades at the NASA Lewis Research Center are used. The codes include computation of acoustic noise generated from a vibrating component, degradation in material properties of a composite laminate at use temperature, dynamic response of acoustically excited hot multilayered composite structure, degradation in the first ply strength of the excited structure due to acoustic loading, and acoustic fatigue resistance of the excited structure, including the propulsion environment. Effects of the laminate lay-up and environment on the acoustic fatigue life are evaluated. The results show that, by keeping the angled plies on the outer surface of the laminate, a substantial increase in the acoustic fatigue life is obtained. The effect of environment (temperature and moisture) is to relieve the residual stresses leading to an increase in the acoustic fatigue life of the excited panel.

Materials science. Dynamic mechanical behavior of multilayer graphene via supersonic projectile penetration.

PubMed

Lee, Jae-Hwang; Loya, Phillip E; Lou, Jun; Thomas, Edwin L

2014-11-28

Multilayer graphene is an exceptional anisotropic material due to its layered structure composed of two-dimensional carbon lattices. Although the intrinsic mechanical properties of graphene have been investigated at quasi-static conditions, its behavior under extreme dynamic conditions has not yet been studied. We report the high-strain-rate behavior of multilayer graphene over a range of thicknesses from 10 to 100 nanometers by using miniaturized ballistic tests. Tensile stretching of the membrane into a cone shape is followed by initiation of radial cracks that approximately follow crystallographic directions and extend outward well beyond the impact area. The specific penetration energy for multilayer graphene is ~10 times more than literature values for macroscopic steel sheets at 600 meters per second. Copyright © 2014, American Association for the Advancement of Science.

Reinforcing effect of graphene on the mechanical properties of Al2O3/TiC ceramics

NASA Astrophysics Data System (ADS)

Li, Zuo-li; Zhao, Jun; Sun, Jia-lin; Gong, Feng; Ni, Xiu-ying

2017-12-01

Multilayer graphene (MLG)-reinforced Al2O3/TiC ceramics were fabricated through hot pressing sintering, and the reinforcing effect of MLG on the microstructure and mechanical properties of the composites was investigated by experiment and simulation. The simulation of dynamic crack initiation and propagation was investigated based on the cohesive zone method. The results show that the composite added with 0.2wt% MLG has excellent flexural strength and high fracture toughness. The major reinforcing mechanisms are the synergistic effect by strong and weak bonding interfaces, MLG pull-out, and grain refinement resulting from the addition of MLG. In addition, the aggravating of crack deflection, branching, blunting, and bridging have indispensable contribution to the improvement of the as-designed materials.

Thermal shock fracture in cross-ply fibre-reinforced ceramic-matrix composites

NASA Astrophysics Data System (ADS)

Kastritseas, C.; Smith, P. A.; Yeomans, J. A.

2010-11-01

The onset of matrix cracking due to thermal shock in a range of simple and multi-layer cross-ply laminates comprising a calcium aluminosilicate (CAS) matrix reinforced with Nicalon® fibres is investigated analytically. A comprehensive stress analysis under conditions of thermal shock, ignoring transient effects, is performed and fracture criteria based on either a recently derived model for the thermal shock resistance of unidirectional Nicalon®/glass ceramic-matrix composites or fracture mechanics considerations are formulated. The effect of material thickness on the apparent thermal shock resistance is also modelled. Comparison with experimental results reveals that the accuracy of the predictions is satisfactory and the reasons for some discrepancies are discussed. In addition, a theoretical argument based on thermal shock theory is formulated to explain the observed cracking patterns.

Future Directions for Selected Topics in Physics and Materials Science

DTIC Science & Technology

2012-07-12

referred to as lightides (e.g. borides , nitrides, phosphides) • Materials for energy conversion, energy storage, energy transport and energy production...Distributed nanosystems and sensors • Strategy for multilayered combinatorics • lightides ( borides , nitrides, phosphides, • New applications for...Strategy for multilayered combinatorics Lightides ( borides , nitrides, phosphides) • Energy conversion, .storage and production • Precision control

Structure and Properties of Azobenzene Thin-Films

NASA Astrophysics Data System (ADS)

Allen, R. A.

1987-09-01

Available from UMI in association with The British Library. A number of monomer and polymer materials, all containing the azobenzene group, have been deposited as Langmuir-Blodgett (LB) multilayers and their structures and physical properties studied. LB films of two monomeric materials exhibited liquid crystal phase changes that were investigated by optical microscopy and X-ray diffraction. Multilayers built up from one of the materials exhibited a phase change upon aging and this demonstrated that the LB technique had produced a structure that was not the equilibrium state. A monomer material possessing a fluorocarbon chain was found to initially deposit as an LB film in a Z-type manner, but changed to Y-type deposition with increasing multilayer thickness. A correlation was observed between this behaviour and the surface potential changes that were brought about when deposition took place on an aluminium substrate. The feasibility of building up alternating multilayers of monomer and polymer materials was demonstrated. Combining these two classes of material in the same LB film may confer on it the mechanical durability of the polymers and the highly ordered structure and potentially interesting physical properties of the monomer. The structures developed here may prove to have high second harmonic generation capabilities. Polymer materials were built up into relatively thick Y-type LB multilayers and studied by X-ray diffraction. Only poorly defined layered structures were found. Polymer materials were also cast into thin films from the melt and from solution. One of the compounds developed a high degree of anisotropy in its structure after exposure to linearly polarised white light. A birefringence of up to Deltan = 0.21 was measured. In contrast, LB films formed from the same material could not be ordered in the same manner and this appeared to result from the very close packing that takes place in such structures.

Process for manufacturing multilayer capacitors

DOEpatents

Lauf, R.J.; Holcombe, C.E.; Dykes, N.L.

1996-01-02

The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation. 4 figs.

Method of making coherent multilayer crystals

DOEpatents

Schuller, Ivan K.; Falco, Charles M.

1984-01-01

A new material consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 .ANG. to 2500 .ANG.. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

Advances in polyelectrolyte multilayer nanofilms as tunable drug delivery systems

PubMed Central

Jiang, Bingbing; Barnett, John B; Li, Bingyun

2009-01-01

There has been considerable interest in polyelectrolyte multilayer nanofilms, which have a variety of applications ranging from optical and electrochemical materials to biomedical devices. Polyelectrolyte multilayer nanofilms are constructed from aqueous solutions using electrostatic layer-by-layer self-assembly of oppositely-charged polyelectrolytes on a solid substrate. Multifunctional polyelectrolyte multilayer nanofilms have been studied using charged dyes, metal and inorganic nanoparticles, DNA, proteins, and viruses. In the past few years, there has been increasing attention to developing polyelectrolyte multilayer nanofilms as drug delivery vehicles. In this mini-review, we present recent developments in polyelectrolyte multilayer nanofilms with tunable drug delivery properties, with particular emphasis on the strategies in tuning the loading and release of drugs in polyelectrolyte multilayer nanofilms as well as their applications. PMID:24198464

Preliminary Reports, Memoranda and Technical Notes of the Materials Research Council Summer Conference, La Jolla, California

DTIC Science & Technology

1983-07-01

Multilayer Thin Film materials M. S. Wrighton ...................................... 26 •.. Line Defects in Langmuir - Blodgett Films J. P. Hirth...of Langmuir and Blodgett can be used to prepare monolayers and multilayers of organic materials on a o, variety of substrates. The films of organic...references therein. * 2. Cf. Thin Solid Films, 99, (1982) from the proceedings of the "* . International Conference on Langmuir - Blodgett Films held

Monte Carlo simulation of ion-material interactions in nuclear fusion devices

NASA Astrophysics Data System (ADS)

Nieto Perez, M.; Avalos-Zuñiga, R.; Ramos, G.

2017-06-01

One of the key aspects regarding the technological development of nuclear fusion reactors is the understanding of the interaction between high-energy ions coming from the confined plasma and the materials that the plasma-facing components are made of. Among the multiple issues important to plasma-wall interactions in fusion devices, physical erosion and composition changes induced by energetic particle bombardment are considered critical due to possible material flaking, changes to surface roughness, impurity transport and the alteration of physicochemical properties of the near surface region due to phenomena such as redeposition or implantation. A Monte Carlo code named MATILDA (Modeling of Atomic Transport in Layered Dynamic Arrays) has been developed over the years to study phenomena related to ion beam bombardment such as erosion rate, composition changes, interphase mixing and material redeposition, which are relevant issues to plasma-aided manufacturing of microelectronics, components on object exposed to intense solar wind, fusion reactor technology and other important industrial fields. In the present work, the code is applied to study three cases of plasma material interactions relevant to fusion devices in order to highlight the code's capabilities: (1) the Be redeposition process on the ITER divertor, (2) physical erosion enhancement in castellated surfaces and (3) damage to multilayer mirrors used on EUV diagnostics in fusion devices due to particle bombardment.

Thin film photovoltaic device

DOEpatents

Catalano, A.W.; Bhushan, M.

1982-08-03

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids. 5 figs.

Photocatalytic degradation effect of malachite green and catalytic hydrogenation by UV-illuminated CeO2/CdO multilayered nanoplatelet arrays: Investigation of antifungal and antimicrobial activities.

PubMed

Maria Magdalane, C; Kaviyarasu, K; Judith Vijaya, J; Jayakumar, C; Maaza, M; Jeyaraj, B

2017-04-01

CeO 2 /CdO multi-layered nanoplatelet arrays have been synthesized by sol-gel method at two different temperatures using Citrus limonum fruit extract and the effect of particle size on the photocatalytic performance is studied. The particle size and phases was analysed by X-ray diffraction pattern (XRD) which brought out the formation of cubic phase in the synthesized samples. Field Emission Scanning electron microscopy (FESEM) revealed the surface morphology and made up of cumulative form of platelet shaped arrays with an average size of 10nm. The elemental composition and the purity of the nanomaterials were confirmed by Energy Dispersive X-ray spectroscopy (EDX). CeO 2 /CdO multilayered binary metal oxide nanoplatelet arrays were formed which was further explored with Fourier transform infrared spectroscopy (FTIR), it reveals that the nanocomposites contain CeO and CdO bonds. Determination of the direct and indirect bandgap energy of the nanoplatelet arrays was carried out by UV-Vis-DRS studies. In MG degradation, both the hole (h + ) and hydroxyl radical (OH) played a major role than the superoxide radical (O 2 - ). Possible photo degradation mechanisms are proposed and discussed in this article. CeO 2 /CdO multi-layered nanoplatelet arrays showed antibacterial activity and among the tested ones, it showed better growth inhibition towards P. aeruginosa MTCC73. Thus, this greener synthetic procedure was a highly effective method due to low-cost, highly effective UV light responsive material for environmental safety. Copyright © 2017. Published by Elsevier B.V.

Surface plasmon resonance-based fiber-optic hydrogen gas sensor utilizing palladium supported zinc oxide multilayers and their nanocomposite.

PubMed

Tabassum, Rana; Gupta, Banshi D

2015-02-10

We analyze surface plasmon resonance-based fiber-optic sensor for sensing of small concentrations of hydrogen gas in the visible region of the electromagnetic spectrum. One of the two probes considered has multilayers of zinc oxide (ZnO) and palladium (Pd) while the other has layer of their composite over a silver coated unclad core of the fiber. The analysis is carried out for different volume fractions of palladium nanoparticles dispersed in zinc oxide host material in the nanocomposite layer. For the analysis, a Maxwell-Garnett model is adopted for calculating the dielectric function of a ZnO:Pd nanocomposite having nanoparticles of dimensions smaller than the wavelength of radiation used. The effects of the volume fraction of the nanoparticles in the nanocomposite and the thickness of the nanocomposite layer on the figure of merit of the sensor have been studied. The film thickness of the layer and the volume fraction of nanoparticles in the ZnO:Pd nanocomposite layer have been optimized to achieve the maximum value of the figure of merit of the sensor. It has been found that the figure of merit of the sensing probe coated with ZnO:Pd nanocomposite is more than twofold of the sensing probe coated with multilayers of Pd and ZnO over a silver coated unclad core of the fiber; hence, the sensor with a nanocomposite layer works better than that with multilayers of zinc oxide and palladium. The sensor can be used for online monitoring and remote sensing of hydrogen gas.

Multilayer thin film design as far ultraviolet quarterwave retarders

NASA Technical Reports Server (NTRS)

Kim, Jongmin; Zukic, Muamer; Torr, Douglas T.; Wilson, Michele M.

1993-01-01

At short wavelengths, such as FUV, transparent, optically active materials are scarce. Reflection phase retardation by a multilayer thin film can be a good alternative in this wavelength region. We design a multilayer quarterwave retarder by calculating the electric fields at each boundary in the multilayer thin film. Using this method, we achieve designs of FUV multilayers which provide high, matched reflectances for both s- and p-polarization states, and at the same time a phase difference between these two states of nearly 90 deg. For example, a quarterwave retarder designed at the Lyman-alpha line (121.6 nm) has 81.05 percent reflectance for the s-polarization and 81.04 percent for the p-polarization state. The phase difference between these two polarization states is 90.07 deg. For convenience the retarders are designed for 45 deg angle of incidence, but our design approach can be used for any other angle of incidence. Aluminum and MgF2 are used as film materials and an opaque thick film of aluminum as the substrate.

Fabrication and characterization of compositionally-graded shape memory alloy films

NASA Astrophysics Data System (ADS)

Cole, Daniel Paul

2009-12-01

The miniaturization of engineering devices has created interest in new actuation methods capable of high power and high frequency responses. Shape memory alloy (SMA) thin films have exhibited one of the highest power densities of any material used in these actuation schemes. However, they currently require complex thermomechanical training in order to be actuated, which becomes more difficult as devices approach the microscale. Previous studies have indicated that SMA films with compositional gradients have the added feature of an intrinsic two-way shape memory effect (SME). In this work, a new method for processing and characterizing compositionally-graded transformable thin films is presented. Graded NiTi SMA films were processed using magnetron sputtering. Single and multilayer graded films were deposited onto bulk NiTi substrates and single crystal silicon substrates, respectively. Annealing the films naturally produced a compositional gradient across the film-substrate or film-film interface through diffusion modification. The films were directly characterized using a combination of atomic force microscopy (AFM), x-ray diffraction and Auger electron spectroscopy. The compositional gradient was indirectly characterized by measuring the variation in mechanical properties as a function of depth using nanoindentation. The similarity of the indentation response on graded films of varying thickness was used to estimate the width of the graded interface. The nanoindentation response was predicted using an analysis that accounted for the transformation effects occurring under the tip during loading and the variation of elastic modulus resulting from the compositional gradient. The recovery mechanisms of the graded films are compared with homogeneous films using a new nanoscale technique. An AFM integrated with a heating and cooling stage was used to observe the recovery of inelastic deformation caused through nanoindentation. The graded films exhibited a two-way SME with a reduced hysteresis, while the homogeneous films exhibited the classical one-way SME. The fabrication and characterization techniques developed in this work have the potential to be applied to general graded and multi-layer film systems.

Optical multilayers with an amorphous fluoropolymer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chow, R.; Loomis, G.E.; Lindsey, E.F.

1994-07-01

Multilayered coatings were made by physical vapor deposition (PVD) of a perfluorinated amorphous polymer, Teflon AF2400, together with other optical materials. A high reflector at 1064 run was made with ZnS and AF2400. An all-organic 1064-nm reflector was made from AF2400 and polyethylene. Oxide (HfO{sub 2}, SiO{sub 2}) compatibility was also tested. Each multilayer system adhered to itself. The multilayers were influenced by coating stress and unintentional temperature rises during PVD deposition.

Tunable self-organization of nanocomposite multilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C. Q.; Pei, Y. T.; Shaha, K. P.

In this letter we report the controlled growth and microstructural evolution of self-assembled nanocomposite multilayers that are induced by surface ion-impingement. The nanoscale structures together with chemical composition, especially at the growing front, have been investigated with high-resolution transmission electron microscopy. Concurrent ion impingement of growing films produces an amorphous capping layer 3 nm in thickness where spatially modulated phase separation is initiated. It is shown that the modulation of multilayers as controlled by the self-organization of nanocrystallites below the capping layer, can be tuned through the entire film.

Development of Al2O3 fiber-reinforced Al2O3-based ceramics.

PubMed

Tanimoto, Yasuhiro; Nemoto, Kimiya

2004-09-01

The purpose of this study was to use a tape casting technique to develop an Al2O3 fiber-reinforced Al2O3-based ceramic material (Al2O3-fiber/Al2O3 composite) into a new type of dental ceramic. The Al2O3-based ceramic used a matrix consisting of 60 wt% Al2O3 powder and 40 wt% SiO2-B2O3 powder. The prepreg sheets of Al2O3-fiber/Al2O3 composite (in which uniaxially aligned Al2O3 fibers were infiltrated with the Al2O3-based matrix) were fabricated continuously using tape casting technique with a doctor blade system. Multilayer preforms of Al2O3-fiber/Al2O3 composite sheets were then sintered at a maximum temperature of 1000 degrees C under an atmospheric pressure in a furnace. The results showed that the shrinkage and bending properties of Al2O3-fiber/Al2O3 composite exceeded those of unreinforced Al2O3--hence demonstrating the positive effects of fiber reinforcement. In conclusion, the tape casting technique has been utilized to successfully develop a new type of dental ceramic material.

Guided waves dispersion equations for orthotropic multilayered pipes solved using standard finite elements code.

PubMed

Predoi, Mihai Valentin

2014-09-01

The dispersion curves for hollow multilayered cylinders are prerequisites in any practical guided waves application on such structures. The equations for homogeneous isotropic materials have been established more than 120 years ago. The difficulties in finding numerical solutions to analytic expressions remain considerable, especially if the materials are orthotropic visco-elastic as in the composites used for pipes in the last decades. Among other numerical techniques, the semi-analytical finite elements method has proven its capability of solving this problem. Two possibilities exist to model a finite elements eigenvalue problem: a two-dimensional cross-section model of the pipe or a radial segment model, intersecting the layers between the inner and the outer radius of the pipe. The last possibility is here adopted and distinct differential problems are deduced for longitudinal L(0,n), torsional T(0,n) and flexural F(m,n) modes. Eigenvalue problems are deduced for the three modes classes, offering explicit forms of each coefficient for the matrices used in an available general purpose finite elements code. Comparisons with existing solutions for pipes filled with non-linear viscoelastic fluid or visco-elastic coatings as well as for a fully orthotropic hollow cylinder are all proving the reliability and ease of use of this method. Copyright © 2014 Elsevier B.V. All rights reserved.

Piezoelectric polymer multilayer on flexible substrate for energy harvesting.

PubMed

Zhang, Lei; Oh, Sharon Roslyn; Wong, Ting Chong; Tan, Chin Yaw; Yao, Kui

2013-09-01

A piezoelectric polymer multilayer structure formed on a flexible substrate is investigated for mechanical energy harvesting under bending mode. Analytical and numerical models are developed to clarify the effect of material parameters critical to the energy harvesting performance of the bending multilayer structure. It is shown that the maximum power is proportional to the square of the piezoelectric stress coefficient and the inverse of dielectric permittivity of the piezoelectric polymer. It is further found that a piezoelectric multilayer with thinner electrodes can generate more electric energy in bending mode. The effect of improved impedance matching in the multilayer polymer on energy output is remarkable. Comparisons between piezoelectric ceramic multilayers and polymer multilayers on flexible substrate are discussed. The fabrication of a P(VDF-TrFE) multilayer structure with a thin Al electrode layer is experimentally demonstrated by a scalable dip-coating process on a flexible aluminum substrate. The results indicate that it is feasible to produce a piezoelectric polymer multilayer structure on flexible substrate for harvesting mechanical energy applicable for many low-power electronics.

Toughening mechanisms in bioinspired multilayered materials.

PubMed

Askarinejad, Sina; Rahbar, Nima

2015-01-06

Outstanding mechanical properties of biological multilayered materials are strongly influenced by nanoscale features in their structure. In this study, mechanical behaviour and toughening mechanisms of abalone nacre-inspired multilayered materials are explored. In nacre's structure, the organic matrix, pillars and the roughness of the aragonite platelets play important roles in its overall mechanical performance. A micromechanical model for multilayered biological materials is proposed to simulate their mechanical deformation and toughening mechanisms. The fundamental hypothesis of the model is the inclusion of nanoscale pillars with near theoretical strength (σth ~ E/30). It is also assumed that pillars and asperities confine the organic matrix to the proximity of the platelets, and, hence, increase their stiffness, since it has been previously shown that the organic matrix behaves more stiffly in the proximity of mineral platelets. The modelling results are in excellent agreement with the available experimental data for abalone nacre. The results demonstrate that the aragonite platelets, pillars and organic matrix synergistically affect the stiffness of nacre, and the pillars significantly contribute to the mechanical performance of nacre. It is also shown that the roughness induced interactions between the organic matrix and aragonite platelet, represented in the model by asperity elements, play a key role in strength and toughness of abalone nacre. The highly nonlinear behaviour of the proposed multilayered material is the result of distributed deformation in the nacre-like structure due to the existence of nano-asperities and nanopillars with near theoretical strength. Finally, tensile toughness is studied as a function of the components in the microstructure of nacre.

Toughening mechanisms in bioinspired multilayered materials

PubMed Central

Askarinejad, Sina; Rahbar, Nima

2015-01-01

Outstanding mechanical properties of biological multilayered materials are strongly influenced by nanoscale features in their structure. In this study, mechanical behaviour and toughening mechanisms of abalone nacre-inspired multilayered materials are explored. In nacre's structure, the organic matrix, pillars and the roughness of the aragonite platelets play important roles in its overall mechanical performance. A micromechanical model for multilayered biological materials is proposed to simulate their mechanical deformation and toughening mechanisms. The fundamental hypothesis of the model is the inclusion of nanoscale pillars with near theoretical strength (σth ~ E/30). It is also assumed that pillars and asperities confine the organic matrix to the proximity of the platelets, and, hence, increase their stiffness, since it has been previously shown that the organic matrix behaves more stiffly in the proximity of mineral platelets. The modelling results are in excellent agreement with the available experimental data for abalone nacre. The results demonstrate that the aragonite platelets, pillars and organic matrix synergistically affect the stiffness of nacre, and the pillars significantly contribute to the mechanical performance of nacre. It is also shown that the roughness induced interactions between the organic matrix and aragonite platelet, represented in the model by asperity elements, play a key role in strength and toughness of abalone nacre. The highly nonlinear behaviour of the proposed multilayered material is the result of distributed deformation in the nacre-like structure due to the existence of nano-asperities and nanopillars with near theoretical strength. Finally, tensile toughness is studied as a function of the components in the microstructure of nacre. PMID:25551150

Shock compression response of cold-rolled Ni/Al multilayer composites

NASA Astrophysics Data System (ADS)

Specht, Paul E.; Weihs, Timothy P.; Thadhani, Naresh N.

2017-01-01

Uniaxial strain, plate-on-plate impact experiments were performed on cold-rolled Ni/Al multilayer composites and the resulting Hugoniot was determined through time-resolved measurements combined with impedance matching. The experimental Hugoniot agreed with that previously predicted by two dimensional (2D) meso-scale calculations [Specht et al., J. Appl. Phys. 111, 073527 (2012)]. Additional 2D meso-scale simulations were performed using the same computational method as the prior study to reproduce the experimentally measured free surface velocities and stress profiles. These simulations accurately replicated the experimental profiles, providing additional validation for the previous computational work.

Multi-Layer Coating of Ultrathin Polymer Films on Nanoparticles of Alumina by a Plasma Treatment

DTIC Science & Technology

2001-01-01

Proc. Vol. 635 © 2001 Materials Research Society Multi-Layer Coating of Ultrathin Polymer Films on Nanoparticles of Alumina by a Plasma Treatment Donglu...interconnected organic and inorganic networks results in coatings with a very low permeability for gases and liquids. Hybrid materials are very suitable for... materials consist of a clear alcoholic solution that can easily be processed by classical application techniques such as dipping, spraying, or spin coating

Mallow Fiber-Reinforced Epoxy Composites in Multilayered Armor for Personal Ballistic Protection

NASA Astrophysics Data System (ADS)

Nascimento, Lucio Fábio Cassiano; Louro, Luis Henrique Leme; Monteiro, Sergio Neves; Lima, Édio Pereira; da Luz, Fernanda Santos

2017-10-01

Lighter and less expensive polymer composites reinforced with natural fibers have been investigated as possible components of a multilayered armor system (MAS) for personal protection against high-velocity ammunition. Their ballistic performance was consistently found comparable with that of conventional Kevlar® synthetic aramid fiber. Among the numerous existing natural fibers with the potential for reinforcing polymer composites to replace Kevlar® in MAS, mallow fiber has not been fully investigated. Thus, the objective of this work is to evaluate the ballistic performance of epoxy composites reinforced with 30 vol.% of aligned mallow fibers as a second MAS layer backing a front ceramic plate. The results using high-velocity 7.62 ammunition show a similar indentation to a Kevlar® layer with the same thickness. An impedance matching calculation supports the similar ballistic performance of mallow fiber composite and Kevlar®. Reduced MAS costs associated with the mallow fiber composite are practical advantages over Kevlar®.

Coherent multilayer crystals and method of making

DOEpatents

Schuller, I.K.; Falco, C.M.

1980-10-30

A new material is described consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 A to 2500 A. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

Glass-mica composite: a new structural thermal-insulating material for building applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Low, N.M.P.

1981-12-01

Homogeneous, rigid glass-mica composites have been synthesized from mixtures of Canadian natural mica flakes of the phlogopite type and ground glass powders prepared from recycled soda-lime waste glasses by a simple sintering process. By means of selection of compositions and processing techniques, composites can be fabricated into products that exhibit a celular structure, a highly densified structure, and multilayer and sandwich structures. The cellular structure composite has a thermal conductivity in the range of 0.165 to 0.230 W/m /sup 0/C when measured over the temperature range 25 to 180/sup 0/C, and a compressive strength of about 0.874 MPa; the highlymore » densified composite, on the other hand, has a thermal conductivity in the range of 0.155 to 0.330 W/m /sup 0/C, a compressive strength in excess of 40 MPa, and an instantaneous coefficient of thermal expansion of 5.8 X 10/sup -6///sup 0/C at 100/sup 0/C. These glass-mica composites exhibit qualities such as insulating efficiency, safety, mechanical strength, and durability that are suitable for engineering applications in building structures or other systems.« less

SnO2@C@VO2 Composite Hollow Nanospheres as an Anode Material for Lithium-Ion Batteries.

PubMed

Guo, Wenbin; Wang, Yong; Li, Qingyuan; Wang, Dongxia; Zhang, Fanchao; Yang, Yiqing; Yu, Yang

2018-05-02

Porous SnO 2 @C@VO 2 composite hollow nanospheres were ingeniously constructed through the combination of layer-by-layer deposition and redox reaction. Moreover, to optimize the electrochemical properties, SnO 2 @C@VO 2 composite hollow nanospheres with different contents of the external VO 2 were also studied. On the one hand, the elastic and conductive carbon as interlayer in the SnO 2 @C@VO 2 composite can not only buffer the huge volume variation during repetitive cycling but also effectively improve electronic conductivity and enhance the utilizing rate of SnO 2 and VO 2 with high theoretical capacity. On the other hand, hollow nanostructures of the composite can be consolidated by the multilayered nanocomponents, resulting in outstanding cyclic stability. In virtue of the above synergetic contribution from individual components, SnO 2 @C@VO 2 composite hollow nanospheres exhibit a large initial discharge capacity (1305.6 mAhg -1 ) and outstanding cyclic stability (765.1 mAhg -1 after 100 cycles). This design of composite hollow nanospheres may be extended to the synthesis of other nanomaterials for electrochemical energy storage.

Corrugated grating on organic multilayer Bragg reflector

NASA Astrophysics Data System (ADS)

Jaquet, Sylvain; Scharf, Toralf; Herzig, Hans Peter

2007-08-01

Polymeric multilayer Bragg structures are combined with diffractive gratings to produce artificial visual color effects. A particular effect is expected due to the angular reflection dependence of the multilayer Bragg structure and the dispersion caused by the grating. The combined effects can also be used to design particular filter functions and various resonant structures. The multilayer Bragg structure is fabricated by spin-coating of two different low-cost polymer materials in solution on a cleaned glass substrate. These polymers have a refractive index difference of about 0.15 and permit multilayer coatings without interlayer problems. Master gratings of different periods are realized by laser beam interference and replicated gratings are superimposed on the multilayer structure by soft embossing in a UV curing glue. The fabrication process requires only polymer materials. The obtained devices are stable and robust. Angular dependent reflection spectrums for the visible are measured. These results show that it is possible to obtain unexpected reflection effects. A rich variety of color spectra can be generated, which is not possible with a single grating. This can be explained by the coupling of transmission of grating orders and the Bragg reflection band. A simple model permits to explain some of the spectral vs angular dependence of reflected light.

Multilayer SnSb4-SbSe Thin Films for Phase Change Materials Possessing Ultrafast Phase Change Speed and Enhanced Stability.

PubMed

Liu, Ruirui; Zhou, Xiao; Zhai, Jiwei; Song, Jun; Wu, Pengzhi; Lai, Tianshu; Song, Sannian; Song, Zhitang

2017-08-16

A multilayer thin film, comprising two different phase change material (PCM) components alternatively deposited, provides an effective means to tune and leverage good properties of its components, promising a new route toward high-performance PCMs. The present study systematically investigated the SnSb 4 -SbSe multilayer thin film as a potential PCM, combining experiments and first-principles calculations, and demonstrated that these multilayer thin films exhibit good electrical resistivity, robust thermal stability, and superior phase change speed. In particular, the potential operating temperature for 10 years is shown to be 122.0 °C and the phase change speed reaches 5 ns in the device test. The good thermal stability of the multilayer thin film is shown to come from the formation of the Sb 2 Se 3 phase, whereas the fast phase change speed can be attributed to the formation of vacancies and a SbSe metastable phase. It is also demonstrated that the SbSe metastable phase contributes to further enhancing the electrical resistivity of the crystalline state and the thermal stability of the amorphous state, being vital to determining the properties of the multilayer SnSb 4 -SbSe thin film.

Hybrid Physical Vapor Deposition Instrument for Advanced Functional Multilayers and Materials

DTIC Science & Technology

2016-04-27

Hybrid Physical Vapor Deposition Instrument for Advanced Functional Multilayers and Materials PI Maria received support to construct a physical...vapor deposition (PVD) system that combines electron beam (e- beam) evaporation, magnetron sputtering, pulsed laser ablation, and ion-assisted deposition ...The instrumentation enables clean, uniform, and rapid deposition of a wide variety of metallic, semiconducting, and ceramic thin films with

Hybrid Physical Vapor Deposition Instrument for Advanced Functional Multilayers and Materials

DTIC Science & Technology

2016-04-27

Hybrid Physical Vapor Deposition Instrument for Advanced Functional Multilayers and Materials PI Maria received support to construct a physical... vapor deposition (PVD) system that combines electron beam (e- beam) evaporation, magnetron sputtering, pulsed laser ablation, and ion-assisted deposition ...peer-reviewed journals: Number of Papers published in non peer-reviewed journals: Final Report: Hybrid Physical Vapor Deposition Instrument for Advanced

Multilayer Nanoporous Graphene Membranes for Water Desalination.

PubMed

Cohen-Tanugi, David; Lin, Li-Chiang; Grossman, Jeffrey C

2016-02-10

While single-layer nanoporous graphene (NPG) has shown promise as a reverse osmosis (RO) desalination membrane, multilayer graphene membranes can be synthesized more economically than the single-layer material. In this work, we build upon the knowledge gained to date toward single-layer graphene to explore how multilayer NPG might serve as a RO membrane in water desalination using classical molecular dynamic simulations. We show that, while multilayer NPG exhibits similarly promising desalination properties to single-layer membranes, their separation performance can be designed by manipulating various configurational variables in the multilayer case. This work establishes an atomic-level understanding of the effects of additional NPG layers, layer separation, and pore alignment on desalination performance, providing useful guidelines for the design of multilayer NPG membranes.

Multiscale mechanics of graphene oxide and graphene based composite films

NASA Astrophysics Data System (ADS)

Cao, Changhong

The mechanical behavior of graphene oxide is length scale dependent: orders of magnitude different between the bulk forms and monolayer counterparts. Understanding the underlying mechanisms plays a significant role in their versatile application. A systematic multiscale mechanical study from monolayer to multilayer, including the interactions between layers of GO, can provide fundamental support for material engineering. In this thesis, an experimental coupled with simulation approach was used to study the multiscale mechanics of graphene oxide (GO) and the methods developed for GO study are proved to be applicable also to mechanical study of graphene based composites. GO is a layered nanomaterial comprised of hierarchical units whose characteristic dimension lies between monolayer GO (0.7 nm - 1.2 nm) and bulk GO papers (≥ 1 mum). Mechanical behaviors of monolayer GO and GO nanosheets (10 nm- 100 nm) were comprehensively studied this work. Monolayer GO was measured to have an average strength of 24.7 GPa,, orders of magnitude higher than previously reported values for GO paper and approximately 50% of the 2D intrinsic strength of pristine graphene. The huge discrepancy between the strength of monolayer GO and that of bulk GO paper motivated the study of GO at the intermediate length scale (GO nanosheets). Experimental results showed that GO nanosheets possess high strength in the gigapascal range. Molecular Dynamic simulations showed that the transition in the failure behavior from interplanar fracture to intraplanar fracture was responsible for the huge strength discrepancy between nanometer scale GO and bulk GO papers. Additionally, the interfacial shear strength between GO layers was found to be a key contributing factor to the distinct mechanical behavior among hierarchical units of GO. The understanding of the multiscale mechanics of GO is transferrable in heterogeneous layered nanomaterials, such as graphene-metal oxide based anode materials in Li-ion batteries. The novel methods developed in this work to study GO multilayered structures were also applied to study the mechanics of graphene-TiO 2 composites. It was found that a critical thickness range of TiO2 deposition on graphene is required for the observed stiffness enhancement effect of graphene to influence the mechanical behavior of the composite.

Multi-layer plastic/glass microfluidic systems containing electrical and mechanical functionality.

PubMed

Han, Arum; Wang, Olivia; Graff, Mason; Mohanty, Swomitra K; Edwards, Thayne L; Han, Ki-Ho; Bruno Frazier, A

2003-08-01

This paper describes an approach for fabricating multi-layer microfluidic systems from a combination of glass and plastic materials. Methods and characterization results for the microfabrication technologies underlying the process flow are presented. The approach is used to fabricate and characterize multi-layer plastic/glass microfluidic systems containing electrical and mechanical functionality. Hot embossing, heat staking of plastics, injection molding, microstenciling of electrodes, and stereolithography were combined with conventional MEMS fabrication techniques to realize the multi-layer systems. The approach enabled the integration of multiple plastic/glass materials into a single monolithic system, provided a solution for the integration of electrical functionality throughout the system, provided a mechanism for the inclusion of microactuators such as micropumps/valves, and provided an interconnect technology for interfacing fluids and electrical components between the micro system and the macro world.

Prediction and characterization of heat-affected zone formation due to neighboring nickel-aluminum multilayer foil reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, David P.; Hirschfeld, Deidre A.; Hooper, Ryan J.

2015-09-01

Reactive multilayer foils have the potential to be used as local high intensity heat sources for a variety of applications. Much of the past research effort concerning these materials have focused on understanding the structure-property relationships of the foils that govern the energy released during a reaction. To enhance the ability of researchers to more rapidly develop technologies based on reactive multilayer foils, a deeper and more predictive understanding of the relationship between the heat released from the foil and microstructural evolution in the neighboring materials is needed. This work describes the development of a numerical model for the purposemore » of evaluating new foil-substrate combinations for screening and optimization. The model is experimentally validated using a commercially available Ni-Al multilayer foils and different alloys.« less

Nano selenium as antioxidant agent in a multilayer food packaging material.

PubMed

Vera, Paula; Echegoyen, Yolanda; Canellas, Elena; Nerín, Cristina; Palomo, María; Madrid, Yolanda; Cámara, Carmen

2016-09-01

Selenium nanoparticles (SeNPs) were incorporated in a flexible multilayer plastic material using a water-base adhesive as vehicle for SeNPs. The antioxidant performance of the original solutions containing spherical SeNPs of 50-60 nm diameter, the adhesive containing these SeNPs, and the final multilayer plastic material to be used as food packaging were quantitatively measured. The radical scavenging capacity due to SeNPs was quantified by a free radical assay developed in the laboratory and by the diphenyl-1-picrylhydrazyl (DPPH) method. DPPH was not efficient to measure the scavenging capacity in the multilayer when the free radical scavenger is not in the surface in contact with it. Several multilayer laminated structures composed by [PET (20 m)-adhesive-LDPE (with variable thickness from 35 to 90 μm)] were prepared and measured, demonstrating for the first time that free radicals derived from oxygen (OH·, O2·, and O2H) cross the PE layer and arrive at the adhesive. SeNPs remain as such after manufacture and the final laminate is stable after 3 months of storage. The antioxidant multilayer is a non-migrating efficient free radical scavenger, able to protect the packaged product versus oxidation and extending the shelf life without being in direct contact with the product. Migration tests of both Se and SeNPs to simulants and hazelnuts demonstrated the non-migrating performance of this new active packaging. Graphical abstract ᅟ.

Effective radiation reduction in Space Station and missions beyond the magnetosphere

NASA Technical Reports Server (NTRS)

Jordan, Thomas M.; Stassinopoulos, E. G.

1989-01-01

This paper investigates the efficiency of low- and high-atomic number materials used as protective shields against biologically effective radiation in doses equivalent to those expected in low-earth-orbit and interplanetary manned missions. Results are presented on calculations for single-material shields from polyethylene, water, Be, Al, Fe, and Ta and multilayer shelds made from the combinations of any two or any three of these materials, for both LEO and interplanetary conditions. It is shown that, whereas for protons and Galactic cosmic rays the ordering of shield materials has a negligible effect, for electrons and secondary bremsstrahlung, both the order and the composition are important parameters. It was found that low-atomic-number materials are most effective shields against protons and galactic cosmic rays, and are most effective in decreasing bremsstrahlung production, while high-atomic-number shields are the best attenuators of both primary electrons (if the dose is dominated by primary electrons) and secondary bremsstrahlung (if this is produced).

Coating multilayer material with improved tribological properties obtained by magnetron sputtering

NASA Astrophysics Data System (ADS)

Mateescu, A. O.; Mateescu, G.; Balasoiu, M.; Pompilian, G. O.; Lungu, M.

2017-02-01

This work is based on the Patent no. RO 128094 B1, granted by the Romanian State Office for Inventions and Trademarks. The goal of the work is to obtain for investigations tribological coatings with multilayer structure with improved tribological properties, deposited by magnetron sputtering process from three materials (sputtering targets). Starting from compound chemical materials (TiC, TiB2 and WC), as sputtering targets, by deposition in argon atmosphere on polished stainless steel, we have obtained, based on the claims of the above patent, thin films of multilayer design with promising results regarding their hardness, elastic modulus, adherence, coefficient of friction and wear resistance. The sputtering process took place in a special sequence in order to ensure better tribological properties to the coating, comparing to those of the individual component materials. The tribological properties, such as the coefficient of friction, are evaluated using the tribometer test.

The possibility of giant dielectric materials for multilayer ceramic capacitors.

PubMed

Ishii, Tatsuya; Endo, Makoto; Masuda, Kenichiro; Ishida, Keisuke

2013-02-11

There have been numerous reports on discovery of giant dielectric permittivity materials called internal barrier layer capacitor in the recent years. We took particular note of one of such materials, i.e., BaTiO 3 with SiO 2 coating. It shows expressions of giant electric permittivity when processed by spark plasma sintering. So we evaluated various electrical characteristics of this material to find out whether it is applicable to multilayer ceramic capacitors. Our evaluation revealed that the isolated surface structure is the sole cause of expressions of giant dielectric permittivity.

Protein-tannic acid multilayer films: A multifunctional material for microencapsulation of food-derived bioactives.

PubMed

Lau, Hooi Hong; Murney, Regan; Yakovlev, Nikolai L; Novoselova, Marina V; Lim, Su Hui; Roy, Nicole; Singh, Harjinder; Sukhorukov, Gleb B; Haigh, Brendan; Kiryukhin, Maxim V

2017-11-01

The benefits of various functional foods are often negated by stomach digestion and poor targeting to the lower gastrointestinal tract. Layer-by-Layer assembled protein-tannic acid (TA) films are suggested as a prospective material for microencapsulation of food-derived bioactive compounds. Bovine serum albumin (BSA)-TA and pepsin-TA films demonstrate linear growth of 2.8±0.1 and 4.2±0.1nm per bi-layer, correspondingly, as shown by ellipsometry. Both multilayer films are stable in simulated gastric fluid but degrade in simulated intestinal fluid. Their corresponding degradation constants are 0.026±0.006 and 0.347±0.005nm -1 min -1 . Milk proteins possessing enhanced adhesion to human intestinal surface, Immunoglobulin G (IgG) and β-Lactoglobulin (BLG), are explored to tailor targeting function to BSA-TA multilayer film. BLG does not adsorb onto the multilayer while IgG is successfully incorporated. Microcapsules prepared from the multilayer demonstrate 2.7 and 6.3 times higher adhesion to Caco-2 cells when IgG is introduced as an intermediate and the terminal layer, correspondingly. This developed material has a great potential for oral delivery of numerous active food-derived ingredients. Copyright © 2017 Elsevier Inc. All rights reserved.

Optimization of TiO2/Cu/TiO2 multilayers as a transparent composite electrode deposited by electron-beam evaporation at room temperature

NASA Astrophysics Data System (ADS)

Sun, Hong-Tao; Wang, Xiao-Ping; Kou, Zhi-Qi; Wang, Li-Jun; Wang, Jin-Ye; Sun, Yi-Qing

2015-04-01

Highly transparent indium-free composite electrodes of TiO2/Cu/TiO2 are deposited by electron-beam evaporation at room temperature. The effects of Cu thickness and annealing temperature on the electrical and optical properties of the multilayer film are investigated. The critical thickness of Cu mid-layer to form a continuous conducting layer is found to be 11 nm. The multilayer with a mid-Cu thickness of 11 nm is optimized to obtain a resistivity of 7.4×10-5 Ω·cm and an average optical transmittance of 86% in the visible spectral range. The figure of merit of the TiO2/Cu(11 nm)/TiO2 multilayer annealed at 150 °C reaches a minimum resistivity of 5.9×10-5 Ω·cm and an average optical transmittance of 88% in the visible spectral range. The experimental results indicate that TiO2/Cu/TiO2 multilayers can be used as a transparent electrode for solar cell and other display applications. Project supported by the Research Innovation Key Project of Education Committee of Shanghai, China (Grant No. 14ZZ137) and the National Cultivation Fund from University of Shanghai for Science and Technology (Grant No. 14XPM04).

Electronic structure of boron based single and multi-layer two dimensional materials

NASA Astrophysics Data System (ADS)

Miyazato, Itsuki; Takahashi, Keisuke

2017-09-01

Two dimensional nanosheets based on boron and Group VA elements are designed and characterized using first principles calculations. B-N, B-P, B-As, B-Sb, and B-Bi are found to possess honeycomb structures where formation energies indicate exothermic reactions. Contrary to B-N, the cases of B-P, B-As, B-Sb, and B-Bi nanosheets are calculated to possess narrow band gaps. In addition, calculations reveal that the electronegativity difference between B and Group VA elements in the designed materials is a good indicator to predict the charge transfer and band gap of the two dimensional materials. Hydrogen adsorption over defect-free B-Sb and B-Bi results in exothermic reactions, while defect-free B-N, B-P, and B-As result in endothermic reactions. The layerability of the designed two dimensional materials is also investigated where the electronic structure of two-layered two dimensional materials is strongly coupled with how the two dimensional materials are layered. Thus, one can consider that the properties of two dimensional materials can be controlled by the composition of two dimensional materials and the structure of layers.

High energy PIXE: A tool to characterize multi-layer thick samples

NASA Astrophysics Data System (ADS)

Subercaze, A.; Koumeir, C.; Métivier, V.; Servagent, N.; Guertin, A.; Haddad, F.

2018-02-01

High energy PIXE is a useful and non-destructive tool to characterize multi-layer thick samples such as cultural heritage objects. In a previous work, we demonstrated the possibility to perform quantitative analysis of simple multi-layer samples using high energy PIXE, without any assumption on their composition. In this work an in-depth study of the parameters involved in the method previously published is proposed. Its extension to more complex samples with a repeated layer is also presented. Experiments have been performed at the ARRONAX cyclotron using 68 MeV protons. The thicknesses and sequences of a multi-layer sample including two different layers of the same element have been determined. Performances and limits of this method are presented and discussed.

Robust optimization of the laser induced damage threshold of dielectric mirrors for high power lasers.

PubMed

Chorel, Marine; Lanternier, Thomas; Lavastre, Éric; Bonod, Nicolas; Bousquet, Bruno; Néauport, Jérôme

2018-04-30

We report on a numerical optimization of the laser induced damage threshold of multi-dielectric high reflection mirrors in the sub-picosecond regime. We highlight the interplay between the electric field distribution, refractive index and intrinsic laser induced damage threshold of the materials on the overall laser induced damage threshold (LIDT) of the multilayer. We describe an optimization method of the multilayer that minimizes the field enhancement in high refractive index materials while preserving a near perfect reflectivity. This method yields a significant improvement of the damage resistance since a maximum increase of 40% can be achieved on the overall LIDT of the multilayer.

Electron beam accelerators—trends in radiation processing technology for industrial and environmental applications in Latin America and the Caribbean

NASA Astrophysics Data System (ADS)

Parejo Calvo, Wilson A.; Duarte, Celina L.; Machado, Luci Diva B.; Manzoli, Jose E.; Geraldo, Aurea Beatriz C.; Kodama, Yasko; Silva, Leonardo Gondim A.; Pino, Eddy S.; Somessari, Elizabeth S. R.; Silveira, Carlos G.; Rela, Paulo R.

2012-08-01

The radiation processing technology for industrial and environmental applications has been developed and used worldwide. In Latin America and the Caribbean and particularly in Brazil there are 24 and 16 industrial electron beam accelerators (EBA) respectively with energy from 200 keV to 10 MeV, operating in private companies and governmental institutions to enhance the physical and chemical properties of materials. However, there are more than 1500 high-current electron beam accelerators in commercial use throughout the world. The major needs and end-use markets for these electron beam (EB) units are R and D, wire and electric cables, heat shrinkable tubes and films, PE foams, tires, components, semiconductors and multilayer packaging films. Nowadays, the emerging opportunities in Latin America and the Caribbean are paints, adhesives and coatings cure in order to eliminate VOCs and for less energy use than thermal process; disinfestations of seeds; and films and multilayer packaging irradiation. For low-energy EBA (from 150 keV to 300 keV). For mid-energy EBA (from 300 keV to 5 MeV), they are flue gas treatment (SO2 and NOX removal); composite and nanocomposite materials; biodegradable composites based on biorenewable resources; human tissue sterilization; carbon and silicon carbide fibers irradiation; irradiated grafting ion-exchange membranes for fuel cells application; electrocatalysts nanoparticles production; and natural polymers irradiation and biodegradable blends production. For high-energy EBA (from 5 MeV to 10 MeV), they are sterilization of medical, pharmaceutical and biological products; gemstone enhancement; treatment of industrial and domestic effluents and sludge; preservation and disinfestations of foods and agricultural products; soil disinfestations; lignocellulosic material irradiation as a pretreatment to produce ethanol biofuel; decontamination of pesticide packing; solid residues remediation; organic compounds removal from wastewater; and treatment of effluent from petroleum production units and liquid irradiation process to treat vessel water ballast. On the other hand, there is a growing need of mobile EB facilities for different applications in South America.

Wrinkled Few-Layer Graphene as Highly Efficient Load Bearer.

PubMed

Androulidakis, Charalampos; Koukaras, Emmanuel N; Rahova, Jaroslava; Sampathkumar, Krishna; Parthenios, John; Papagelis, Konstantinos; Frank, Otakar; Galiotis, Costas

2017-08-09

Multilayered graphitic materials are not suitable as load-bearers due to their inherent weak interlayer bonding (for example, graphite is a solid lubricant in certain applications). This situation is largely improved when two-dimensional (2D) materials such as a monolayer (SLG) graphene are employed. The downside in these cases is the presence of thermally or mechanically induced wrinkles which are ubiquitous in 2D materials. Here we set out to examine the effect of extensive large wavelength/amplitude wrinkling on the stress transfer capabilities of exfoliated simply supported graphene flakes. Contrary to common belief we present clear evidence that this type of "corrugation" enhances the load-bearing capacity of few-layer graphene as compared to "flat" specimens. This effect is the result of the significant increase of the graphene/polymer interfacial shear stress per increment of applied strain due to wrinkling and paves the way for designing affordable graphene composites with highly improved stress-transfer efficiency.

Nanomaterials and preservation mechanisms of architecture monuments

NASA Astrophysics Data System (ADS)

Ion, Rodica-Mariana; Radu, Adrian; Teodorescu, Sofia; Fierǎscu, Irina; Fierǎscu, Radu-Claudiu; Ştirbescu, Raluca-Maria; Dulamǎ, Ioana Daniela; Şuicǎ-Bunghez, Ioana-Raluca; Bucuricǎ, Ioan Alin; Ion, Mihaela-Lucia

2016-12-01

Knowledge of the chemical composition of the building materials of the monuments may help us to preserve and protect them from the pollution of our cities. The aim of this work is to characterize the materials of the walls from ancient buildings, the decay products that could be appear due to the action of pollution and a new method based on nanomaterials (hydroxyapatite -HAp) for a conservative preservation of the treated walls. Some analytical techniques have been used, as follow: X-ray fluorescence energy dispersive (EDXRF) (for the relative abundance of major, minor and trace elements), FTIR and Raman spectroscopy (for stratigraphic study of cross-sections of multi-layered materials found in wall paintings), Optical microscopy (OM), (for morphology of the wall samples). The nanomaterial suspension HAp applied on the sample surface by spraying, decreased the capillary water uptake, do not modify significantly the color of the samples and induced a reduced mass loss for the treated samples.

Superconducting composite with multilayer patterns and multiple buffer layers

DOEpatents

Wu, X.D.; Muenchausen, R.E.

1993-10-12

An article of manufacture is described including a substrate, a patterned interlayer of a material selected from the group consisting of magnesium oxide, barium-titanium oxide or barium-zirconium oxide, the patterned interlayer material overcoated with a secondary interlayer material of yttria-stabilized zirconia or magnesium-aluminum oxide, upon the surface of the substrate whereby an intermediate article with an exposed surface of both the overcoated patterned interlayer and the substrate is formed, a coating of a buffer layer selected from the group consisting of cerium oxide, yttrium oxide, curium oxide, dysprosium oxide, erbium oxide, europium oxide, iron oxide, gadolinium oxide, holmium oxide, indium oxide, lanthanum oxide, manganese oxide, lutetium oxide, neodymium oxide, praseodymium oxide, plutonium oxide, samarium oxide, terbium oxide, thallium oxide, thulium oxide, yttrium oxide and ytterbium oxide over the entire exposed surface of the intermediate article, and, a ceramic superconductor. 5 figures.

Empirical potential for molecular simulation of graphene nanoplatelets

NASA Astrophysics Data System (ADS)

Bourque, Alexander J.; Rutledge, Gregory C.

2018-04-01

A new empirical potential for layered graphitic materials is reported. Interatomic interactions within a single graphene sheet are modeled using a Stillinger-Weber potential. Interatomic interactions between atoms in different sheets of graphene in the nanoplatelet are modeled using a Lennard-Jones interaction potential. The potential is validated by comparing molecular dynamics simulations of tensile deformation with the reported elastic constants for graphite. The graphite is found to fracture into graphene nanoplatelets when subjected to ˜15% tensile strain normal to the basal surface of the graphene stack, with an ultimate stress of 2.0 GPa and toughness of 0.33 GPa. This force field is useful to model molecular interactions in an important class of composite systems comprising 2D materials like graphene and multi-layer graphene nanoplatelets.

Frictionless Contact of Multilayered Composite Half Planes Containing Layers With Complex Eigenvalues

NASA Technical Reports Server (NTRS)

Zhang, Wang; Binienda, Wieslaw K.; Pindera, Marek-Jerzy

1997-01-01

A previously developed local-global stiffness matrix methodology for the response of a composite half plane, arbitrarily layered with isotropic, orthotropic or monoclinic plies, to indentation by a rigid parabolic punch is further extended to accommodate the presence of layers with complex eigenvalues (e.g., honeycomb or piezoelectric layers). First, a generalized plane deformation solution for the displacement field in an orthotropic layer or half plane characterized by complex eigenvalues is obtained using Fourier transforms. A local stiffness matrix in the transform domain is subsequently constructed for this class of layers and half planes, which is then assembled into a global stiffness matrix for the entire multilayered half plane by enforcing continuity conditions along the interfaces. Application of the mixed boundary condition on the top surface of the half plane indented by a rigid punch results in an integral equation for the unknown pressure in the contact region. The integral possesses a divergent kernel which is decomposed into Cauchy-type and regular parts using the asymptotic properties of the local stiffness matrix and a relationship between Fourier and finite Hilbert transform of the contact pressure. The solution of the resulting singular integral equation is obtained using a collocation technique based on the properties of orthogonal polynomials developed by Erdogan and Gupta. Examples are presented that illustrate the important influence of low transverse properties of layers with complex eigenvalues, such as those exhibited by honeycomb, on the load versus contact length response and contact pressure distributions for half planes containing typical composite materials.

Rheological Characteristics of 2D Titanium Carbide (MXene) Dispersions: A Guide for Processing MXenes.

PubMed

Akuzum, Bilen; Maleski, Kathleen; Anasori, Babak; Lelyukh, Pavel; Alvarez, Nicolas Javier; Kumbur, E Caglan; Gogotsi, Yury

2018-03-27

Understanding the rheological properties of two-dimensional (2D) materials in suspension is critical for the development of various solution processing and manufacturing techniques. 2D carbides and nitrides (MXenes) constitute one of the largest families of 2D materials with >20 synthesized compositions and applications already ranging from energy storage to medicine to optoelectronics. However, in spite of a report on clay-like behavior, not much is known about their rheological response. In this study, rheological behavior of single- and multilayer Ti 3 C 2 T x in aqueous dispersions was investigated. Viscous and viscoelastic properties of MXene dispersions were studied over a variety of concentrations from colloidal dispersions to high loading slurries, showing that a multilayer MXene suspension with up to 70 wt % can exhibit flowability. Processing guidelines for the fabrication of MXene films, coatings, and fibers have been established based on the rheological properties. Surprisingly, high viscosity was observed at very low concentrations for solutions of single-layer MXene flakes. Single-layer colloidal solutions were found to exhibit partial elasticity even at the lowest tested concentrations (<0.20 mg/mL) due to the presence of strong surface charge and excellent hydrophilicity of MXene, making them amenable to fabrication at dilute concentrations. Overall, the findings of this study provide fundamental insights into the rheological response of this quickly growing 2D family of materials in aqueous environments as well as offer guidelines for processing of MXenes.

Diffusion-Based Design of Multi-Layered Ophthalmic Lenses for Controlled Drug Release

PubMed Central

Pimenta, Andreia F. R.; Serro, Ana Paula; Paradiso, Patrizia; Saramago, Benilde

2016-01-01

The study of ocular drug delivery systems has been one of the most covered topics in drug delivery research. One potential drug carrier solution is the use of materials that are already commercially available in ophthalmic lenses for the correction of refractive errors. In this study, we present a diffusion-based mathematical model in which the parameters can be adjusted based on experimental results obtained under controlled conditions. The model allows for the design of multi-layered therapeutic ophthalmic lenses for controlled drug delivery. We show that the proper combination of materials with adequate drug diffusion coefficients, thicknesses and interfacial transport characteristics allows for the control of the delivery of drugs from multi-layered ophthalmic lenses, such that drug bursts can be minimized, and the release time can be maximized. As far as we know, this combination of a mathematical modelling approach with experimental validation of non-constant activity source lamellar structures, made of layers of different materials, accounting for the interface resistance to the drug diffusion, is a novel approach to the design of drug loaded multi-layered contact lenses. PMID:27936138

A particle swarm-based algorithm for optimization of multi-layered and graded dental ceramics.

PubMed

Askari, Ehsan; Flores, Paulo; Silva, Filipe

2018-01-01

The thermal residual stresses (TRSs) generated owing to the cooling down from the processing temperature in layered ceramic systems can lead to crack formation as well as influence the bending stress distribution and the strength of the structure. The purpose of this study is to minimize the thermal residual and bending stresses in dental ceramics to enhance their strength as well as to prevent the structure failure. Analytical parametric models are developed to evaluate thermal residual stresses in zirconia-porcelain multi-layered and graded discs and to simulate the piston-on-ring test. To identify optimal designs of zirconia-based dental restorations, a particle swarm optimizer is also developed. The thickness of each interlayer and compositional distribution are referred to as design variables. The effect of layers number constituting the interlayer between two based materials on the performance of graded prosthetic systems is also investigated. The developed methodology is validated against results available in literature and a finite element model constructed in the present study. Three different cases are considered to determine the optimal design of graded prosthesis based on minimizing (a) TRSs; (b) bending stresses; and (c) both TRS and bending stresses. It is demonstrated that each layer thickness and composition profile have important contributions into the resulting stress field and magnitude. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modelling single shot damage thresholds of multilayer optics for high-intensity short-wavelength radiation sources.

PubMed

Loch, R A; Sobierajski, R; Louis, E; Bosgra, J; Bijkerk, F

2012-12-17

The single shot damage thresholds of multilayer optics for high-intensity short-wavelength radiation sources are theoretically investigated, using a model developed on the basis of experimental data obtained at the FLASH and LCLS free electron lasers. We compare the radiation hardness of commonly used multilayer optics and propose new material combinations selected for a high damage threshold. Our study demonstrates that the damage thresholds of multilayer optics can vary over a large range of incidence fluences and can be as high as several hundreds of mJ/cm(2). This strongly suggests that multilayer mirrors are serious candidates for damage resistant optics. Especially, multilayer optics based on Li(2)O spacers are very promising for use in current and future short-wavelength radiation sources.

TiN films fabricated by reactive gas pulse sputtering: A hybrid design of multilayered and compositionally graded structures

NASA Astrophysics Data System (ADS)

Yang, Jijun; Zhang, Feifei; Wan, Qiang; Lu, Chenyang; Peng, Mingjing; Liao, Jiali; Yang, Yuanyou; Wang, Lumin; Liu, Ning

2016-12-01

Reactive gas pulse (RGP) sputtering approach was used to prepare TiN thin films through periodically changing the N2/Ar gas flow ratio. The obtained RGPsbnd TiN film possessed a hybrid architecture containing compositionally graded and multilayered structures, composed of hcp Ti-phase and fcc TiN-phase sublayers. Meanwhile, the RGP-TiN film exhibited a composition-oscillation along the film thickness direction, where the Ti-phase sublayer had a compositional gradient and the TiN-phase retained a constant stoichiometric ratio of Ti:N ≈ 1. The film modulation ratio λ (the thicknesses ratio of the Ti and TiN-phase sublayer) can be effectively tuned by controlling the undulation behavior of the N2 partial flow rate. Detailed analysis showed that this hybrid structure originated from a periodic transition of the film growth mode during the reactive sputtering process.

Observation of van Hove Singularities in Twisted Silicene Multilayers.

PubMed

Li, Zhi; Zhuang, Jincheng; Chen, Lan; Ni, Zhenyi; Liu, Chen; Wang, Li; Xu, Xun; Wang, Jiaou; Pi, Xiaodong; Wang, Xiaolin; Du, Yi; Wu, Kehui; Dou, Shi Xue

2016-08-24

Interlayer interactions perturb the electronic structure of two-dimensional materials and lead to new physical phenomena, such as van Hove singularities and Hofstadter's butterfly pattern. Silicene, the recently discovered two-dimensional form of silicon, is quite unique, in that silicon atoms adopt competing sp(2) and sp(3) hybridization states leading to a low-buckled structure promising relatively strong interlayer interaction. In multilayer silicene, the stacking order provides an important yet rarely explored degree of freedom for tuning its electronic structures through manipulating interlayer coupling. Here, we report the emergence of van Hove singularities in the multilayer silicene created by an interlayer rotation. We demonstrate that even a large-angle rotation (>20°) between stacked silicene layers can generate a Moiré pattern and van Hove singularities due to the strong interlayer coupling in multilayer silicene. Our study suggests an intriguing method for expanding the tunability of the electronic structure for electronic applications in this two-dimensional material.

Method of fabricating reflection-mode EUV diffraction elements

DOEpatents

Naulleau, Patrick P.

2002-01-01

Techniques for fabricating a well-controlled, quantized-level, engineered surface that serves as substrates for EUV reflection multilayer overcomes problems associated with the fabrication of reflective EUV diffraction elements. The technique when employed to fabricate an EUV diffraction element that includes the steps of: (a) forming an etch stack comprising alternating layers of first and second materials on a substrate surface where the two material can provide relative etch selectivity; (b) creating a relief profile in the etch stack wherein the relief profile has a defined contour; and (c) depositing a multilayer reflection film over the relief profile wherein the film has an outer contour that substantially matches that of the relief profile. For a typical EUV multilayer, if the features on the substrate are larger than 50 nm, the multilayer will be conformal to the substrate. Thus, the phase imparted to the reflected wavefront will closely match that geometrically set by the surface height profile.

Si nanocrystals-based multilayers for luminescent and photovoltaic device applications

NASA Astrophysics Data System (ADS)

Lu, Peng; Li, Dongke; Cao, Yunqing; Xu, Jun; Chen, Kunji

2018-06-01

Low dimensional Si materials have attracted much attention because they can be developed in many kinds of new-generation nano-electronic and optoelectronic devices, among which Si nanocrystals-based multilayered material is one of the most promising candidates and has been extensively studied. By using multilayered structures, the size and distribution of nanocrystals as well as the barrier thickness between two adjacent Si nanocrystal layers can be well controlled, which is beneficial to the device applications. This paper presents an overview of the fabrication and device applications of Si nanocrystals, especially in luminescent and photovoltaic devices. We first introduce the fabrication methods of Si nanocrystals-based multilayers. Then, we systematically review the utilization of Si nanocrystals in luminescent and photovoltaic devices. Finally, some expectations for further development of the Si nanocrystals-based photonic and photovoltaic devices are proposed. Project supported by the National Natural Science Foundation of China (Nos. 11774155, 11274155).

Layering, interface and edge effects in multi-layered composite medium

NASA Technical Reports Server (NTRS)

Datta, S. K.; Shah, A. H.; Karunesena, W.

1990-01-01

Guided waves in a cross-ply laminated plate are studied. Because of the complexity of the exact dispersion equation that governs the wave propagation in a multi-layered fiber-reinforced plate, a stiffness method that can be applied to any number of layers is presented. It is shown that, for a sufficiently large number of layers, the plate can be modeled as a homogeneous anisotropic plate. Also studied is the reflection of guided waves from the edge of a multilayered plate. These results are quite different than in the case of a single homogeneous plate.

Strained multilayer structures with pseudomorphic GeSiSn layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timofeev, V. A., E-mail: Vyacheslav.t@isp.nsc.ru; Nikiforov, A. I.; Tuktamyshev, A. R.

2016-12-15

The temperature and composition dependences of the critical thickness of the 2D–3D transition for a GeSiSn film on Si(100) have been studied. The regularities of the formation of multilayer structures with pseudomorphic GeSiSn layers directly on a Si substrate, without relaxed buffer layers, were investigated for the first time. The possibility of forming multilayer structures based on pseudomorphic GeSiSn layers has been shown and the lattice parameters have been determined using transmission electron microscopy. The grown structures demonstrate photoluminescence for Sn contents from 3.5 to 5% in GeSiSn layers.

Recent advances in aerospace composite NDE

NASA Astrophysics Data System (ADS)

Georgeson, Gary E.

2002-06-01

As the aerospace industry continues to advance the design and use of composite structure, the NDE community faces the difficulties of trying to keep up. The challenges lie in manufacturing evaluation of the newest aerospace structures and materials and the in-service inspection and monitoring of damaged or aging composites. This paper provides examples of several promising NDI applications in the world of aerospace composites. Airborne (or non-contact) Ultrasonic Testing (UT) has been available for decades, but recently has generated new interest due to significant improvements in transducer design and low noise electronics. Boeing is developing inspection techniques for composite joints and core blankets using this technology. In-service inspection techniques for thick, multi-layer structures are also being advanced. One effective technique integrates the S-9 Sondicator, a traditional bond testing device, with Boeing's Mobile Automated Scanner (MAUS) platform. Composite patches have seen limited use on-aircraft, due, in part, to the difficulty of determining the quality of a bonded joint. A unique approach using Electronic Speckle Pattern Interferometry (ESPI) is showing promise as a bonded patch-inspection method. Other NDI techniques currently being developed for aerospace application are also briefly discussed.

Pointillist structural color in Pollia fruit

PubMed Central

Vignolini, Silvia; Rudall, Paula J.; Rowland, Alice V.; Reed, Alison; Moyroud, Edwige; Faden, Robert B.; Baumberg, Jeremy J.; Glover, Beverley J.; Steiner, Ullrich

2012-01-01

Biological communication by means of structural color has existed for at least 500 million years. Structural color is commonly observed in the animal kingdom, but has been little studied in plants. We present a striking example of multilayer-based strong iridescent coloration in plants, in the fruit of Pollia condensata. The color is caused by Bragg reflection of helicoidally stacked cellulose microfibrils that form multilayers in the cell walls of the epicarp. We demonstrate that animals and plants have convergently evolved multilayer-based photonic structures to generate colors using entirely distinct materials. The bright blue coloration of this fruit is more intense than that of any previously described biological material. Uniquely in nature, the reflected color differs from cell to cell, as the layer thicknesses in the multilayer stack vary, giving the fruit a striking pixelated or pointillist appearance. Because the multilayers form with both helicoidicities, optical characterization reveals that the reflected light from every epidermal cell is polarized circularly either to the left or to the right, a feature that has never previously been observed in a single tissue. PMID:23019355

Chemical and morphological characterization of III-V strained layered heterostructures

NASA Astrophysics Data System (ADS)

Gray, Allen Lindsay

This dissertation describes investigations into the chemical and morphological characterization of III-V strained layered heterostructures by high-resolution x-ray diffraction. The purpose of this work is two-fold. The first was to use high-resolution x-ray diffraction coupled with transmission electron microscopy to characterize structurally a quaternary AlGaAsSb/InGaAsSb multiple quantum well heterostructure laser device. A method for uniquely determining the chemical composition of the strain quaternary quantum well, information previously thought to be unattainable using high resolution x-ray diffraction is thoroughly described. The misconception that high-resolution x-ray diffraction can separately find the well and barrier thickness of a multi-quantum well from the pendellosung fringe spacing is corrected, and thus the need for transmission electron microscopy is motivated. Computer simulations show that the key in finding the well composition is the intensity of the -3rd order satellite peaks in the diffraction pattern. The second part of this work addresses the evolution of strain relief in metastable multi-period InGaAs/GaAs multi-layered structures by high-resolution x-ray reciprocal space maps. Results are accompanied by transmission electron and differential contrast microscopy. The evolution of strain relief is tracked from a coherent "pseudomorphic" growth to a dislocated state as a function of period number by examining the x-ray diffuse scatter emanating from the average composition (zeroth-order) of the multi-layer. Relaxation is determined from the relative positions of the substrate with respect to the zeroth-order peak. For the low period number, the diffuse scatter from the multi-layer structure region arises from periodic, coherent crystallites. For the intermediate period number, the displacement fields around the multi-layer structure region transition to random coherent crystallites. At the higher period number, displacement fields of overlapping dislocations from relaxation of the random crystallites cause the initial stages of relaxation of the multi-layer structure. At the highest period number studied, relaxation of the multi-layer structure becomes bi-modal characterized by overlapping dislocations caused by mosaic block relaxation and periodically spaced misfit dislocations formed by 60°-type dislocations. The relaxation of the multi-layer structure has an exponential dependence on the diffuse scatter length-scale, which is shown to be a sensitive measure of the onset of relaxation.

Three-dimensional bioprinting of rat embryonic neural cells.

PubMed

Lee, Wonhye; Pinckney, Jason; Lee, Vivian; Lee, Jong-Hwan; Fischer, Krisztina; Polio, Samuel; Park, Je-Kyun; Yoo, Seung-Schik

2009-05-27

We present a direct cell printing technique to pattern neural cells in a three-dimensional (3D) multilayered collagen gel. A layer of collagen precursor was printed to provide a scaffold for the cells, and the rat embryonic neurons and astrocytes were subsequently printed on the layer. A solution of sodium bicarbonate was applied to the cell containing collagen layer as nebulized aerosols, which allowed the gelation of the collagen. This process was repeated layer-by-layer to construct the 3D cell-hydrogel composites. Upon characterizing the relationship between printing resolutions and the growth of printed neural cells, single/multiple layers of neural cell-hydrogel composites were constructed and cultured. The on-demand capability to print neural cells in a multilayered hydrogel scaffold offers flexibility in generating artificial 3D neural tissue composites.

Measuring Moisture Levels in Graphite Epoxy Composite Sandwich Structures

NASA Technical Reports Server (NTRS)

Nurge, Mark; Youngquist, Robert; Starr, Stanley

2011-01-01

Graphite epoxy composite (GEC) materials are used in the construction of rocket fairings, nose cones, interstage adapters, and heat shields due to their high strength and light weight. However, they absorb moisture depending on the environmental conditions they are exposed to prior to launch. Too much moisture absorption can become a problem when temperature and pressure changes experienced during launch cause the water to vaporize. The rapid state change of the water can result in structural failure of the material. In addition, heat and moisture combine to weaken GEC structures. Diffusion models that predict the total accumulated moisture content based on the environmental conditions are one accepted method of determining if the material strength has been reduced to an unacceptable level. However, there currently doesn t exist any field measurement technique to estimate the actual moisture content of a composite structure. A multi-layer diffusion model was constructed with Mathematica to predict moisture absorption and desorption from the GEC sandwich structure. This model is used in conjunction with relative humidity/temperature sensors both on the inside and outside of the material to determine the moisture levels in the structure. Because the core materials have much higher diffusivity than the face sheets, a single relative humidity measurement will accurately reflect the moisture levels in the core. When combined with an external relative humidity measurement, the model can be used to determine the moisture levels in the face sheets. Since diffusion is temperaturedependent, the temperature measurements are used to determine the diffusivity of the face sheets for the model computations.

Multi-functional composite materials for catalysis and chemical mechanical planarization

NASA Astrophysics Data System (ADS)

Coutinho, Cecil A.

2009-12-01

Composite materials formed from two or more functionally different materials offer a versatile avenue to create a tailored material with well defined traits. Within this dissertation research, multi-functional composites were synthesized based on organic and inorganic materials. The functionally of these composites was experimentally tested and a semi-empirical model describing the sedimentation behavior of these particles was developed. This first objective involved the fabrication of microcomposites consisting of titanium dioxide (TiO2) nanoparticles confined within porous, microgels of a thermo-responsive polymer for use in the photocatalytic treatment of wastewater. TiO2 has been shown to be an excellent photocatalyst with potential applications in advanced oxidative processes such as wastewater remediation. Upon UV irradiation, short-lived electron-hole pairs are generated, which produce oxidative species that degrade simple organic contaminants. The rapid sedimentation of these microcomposites provided an easy gravimetric separation after remediation. Methyl orange was used as a model organic contaminant to investigate the kinetics of photodegradation under a range of concentrations and pH conditions. Although after prolonged periods of UV irradiation (˜8-13 hrs), the titania-microgels also degrade, regeneration of the microcomposites was straightforward via the addition of polymer microgels with no loss in photocatalytic activity of the reformed microcomposites. The second objective within this dissertation involved the systematic development of abrasive microcomposite particles containing well dispersed nanoparticles of ceria in an organic/inorganic hybrid polymeric particle for use in chemical mechanical polishing/planarization (CMP). A challenge in IC fabrication involves the defect-free planarization of silicon oxide films for successful multi-layer deposition. Planarization studies conducted with the microcomposites prepared in this research, yield very smooth, planar surfaces with removal rates that rival those of inorganic oxides slurries typically used in industry. The density and size of these ceria-microgel particles could be controlled by varying the temperature or composition during synthesis, leading to softer or harder polishing when desired.

Effect of γ-irradiation on commercial polypropylene based mono and multi-layered retortable food packaging materials

NASA Astrophysics Data System (ADS)

George, Johnsy; Kumar, R.; Sajeevkumar, V. A.; Sabapathy, S. N.; Vaijapurkar, S. G.; Kumar, D.; Kchawahha, A.; Bawa, A. S.

2007-07-01

Irradiation processing of food in the prepackaged form may affect chemical and physical properties of the plastic packaging materials. The effect of γ-irradiation doses (2.5-10.0 kGy) on polypropylene (PP)-based retortable food packaging materials, were investigated using Fourier transform infrared (FTIR) spectroscopic analysis, which revealed the changes happening to these materials after irradiation. The mechanical properties decreased with irradiation while oxygen transmission rate (OTR) was not affected significantly. Colour measurement indicated that Nylon 6 containing multilayer films became yellowish after irradiation. Thermal characterization revealed the changes in percentage crystallinity.

Layered reactive particles with controlled geometries, energies, and reactivities, and methods for making the same

DOEpatents

Fritz, Gregory M.; Weihs, Timothy P.; Grzyb, Justin A.

2016-07-05

An energetic composite having a plurality of reactive particles each having a reactive multilayer construction formed by successively depositing reactive layers on a rod-shaped substrate having a longitudinal axis, dividing the reactive-layer-deposited rod-shaped substrate into a plurality of substantially uniform longitudinal segments, and removing the rod-shaped substrate from the longitudinal segments, so that the reactive particles have a controlled, substantially uniform, cylindrically curved or otherwise rod-contoured geometry which facilitates handling and improves its packing fraction, while the reactant multilayer construction controls the stability, reactivity and energy density of the energetic composite.

Analysis of multi-layered films. [determining dye densities by applying a regression analysis to the spectral response of the composite transparency

NASA Technical Reports Server (NTRS)

Scarpace, F. L.; Voss, A. W.

1973-01-01

Dye densities of multi-layered films are determined by applying a regression analysis to the spectral response of the composite transparency. The amount of dye in each layer is determined by fitting the sum of the individual dye layer densities to the measured dye densities. From this, dye content constants are calculated. Methods of calculating equivalent exposures are discussed. Equivalent exposures are a constant amount of energy over a limited band-width that will give the same dye content constants as the real incident energy. Methods of using these equivalent exposures for analysis of photographic data are presented.

Layered reactive particles with controlled geometries, energies, and reactivities, and methods for making the same

DOEpatents

Fritz, Gregory M; Knepper, Robert Allen; Weihs, Timothy P; Gash, Alexander E; Sze, John S

2013-04-30

An energetic composite having a plurality of reactive particles each having a reactive multilayer construction formed by successively depositing reactive layers on a rod-shaped substrate having a longitudinal axis, dividing the reactive-layer-deposited rod-shaped substrate into a plurality of substantially uniform longitudinal segments, and removing the rod-shaped substrate from the longitudinal segments, so that the reactive particles have a controlled, substantially uniform, cylindrically curved or otherwise rod-contoured geometry which facilitates handling and improves its packing fraction, while the reactant multilayer construction controls the stability, reactivity and energy density of the energetic composite.

Nonlinear multilayers as optical limiters

NASA Astrophysics Data System (ADS)

Turner-Valle, Jennifer Anne

1998-10-01

In this work we present a non-iterative technique for computing the steady-state optical properties of nonlinear multilayers and we examine nonlinear multilayer designs for optical limiters. Optical limiters are filters with intensity-dependent transmission designed to curtail the transmission of incident light above a threshold irradiance value in order to protect optical sensors from damage due to intense light. Thin film multilayers composed of nonlinear materials exhibiting an intensity-dependent refractive index are used as the basis for optical limiter designs in order to enhance the nonlinear filter response by magnifying the electric field in the nonlinear materials through interference effects. The nonlinear multilayer designs considered in this work are based on linear optical interference filter designs which are selected for their spectral properties and electric field distributions. Quarter wave stacks and cavity filters are examined for their suitability as sensor protectors and their manufacturability. The underlying non-iterative technique used to calculate the optical response of these filters derives from recognizing that the multi-valued calculation of output irradiance as a function of incident irradiance may be turned into a single-valued calculation of incident irradiance as a function of output irradiance. Finally, the benefits and drawbacks of using nonlinear multilayer for optical limiting are examined and future research directions are proposed.

Magnetic and electrical properties of FeSi/FeSi-ZrO 2 multilayers prepared by EB-PVD

NASA Astrophysics Data System (ADS)

Bi, Xiaofang; Lan, Weihua; Ou, Shengquan; Gong, Shengkai; Xu, Huibin

2003-04-01

FeSi/FeSi-ZrO 2 and FeSi/ZrO 2 multilayer materials were prepared by electron beam physical vapor deposition with the FeSi-ZrO 2 layer thickness about 0.6 μm, and their magnetic and electrical properties were studied as a function of FeSi layer thickness. With increasing FeSi layer thickness from 0.3 to 3 μm, the coercivity decreased from 0.92 to 0.31 kA/m and the saturation magnetization changed from 164 to 186 emu/g. The effect of the layer number on the magnetic properties was discussed in terms of interfacial mixing and oxidation. It was also discovered that the magnetic properties of the multilayer materials were affected by the spacer material, exhibiting higher saturation magnetization and lower coercivity for the FeSi/FeSi-ZrO 2 than those for the FeSi/ZrO 2 with the same individual layer thicknesses. This behavior could be explained by the weaker magnetic interaction between FeSi layers separated by the non-magnetic ZrO 2 layer. Furthermore, the electrical resistivity changed from 1850 to 1250 μΩ cm for the multilayer materials for the FeSi thickness increasing from 0.30 to 3 μm.

DOE-EPSCoR. Exchange interactions in epitaxial intermetallic layered systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

LeClair, Patrick R.; Gary, Mankey J.

2015-05-25

The goal of this research is to develop a fundamental understanding of the exchange interactions in epitaxial intermetallic alloy thin films and multilayers, including films and multilayers of Fe-Pt, Co-Pt and Fe-P-Rh alloys deposited on MgO and Al2O3 substrates. Our prior results have revealed that these materials have a rich variety of ferromagnetic, paramagnetic and antiferromagnetic phases which are sensitive functions of composition, substrate symmetry and layer thickness. Epitaxial antiferromagnetic films of FePt alloys exhibit a different phase diagram than bulk alloys. The antiferromagnetism of these materials has both spin ordering transitions and spin orienting transitions. The objectives include themore » study of exchange-inversion materials and the interface of these materials with ferromagnets. Our aim is to formulate a complete understanding of the magnetic ordering in these materials, as well as developing an understanding of how the spin structure is modified through contact with a ferromagnetic material at the interface. The ultimate goal is to develop the ability to tune the phase diagram of the materials to produce layered structures with tunable magnetic properties. The alloy systems that we will study have a degree of complexity and richness of magnetic phases that requires the use of the advanced tools offered by the DOE-operated national laboratory facilities, such as neutron and x-ray scattering to measure spin ordering, spin orientations, and element-specific magnetic moments. We plan to contribute to DOE’s mission of producing “Materials by Design” with properties determined by alloy composition and crystal structure. We have developed the methods for fabricating and have performed neutron diffraction experiments on some of the most interesting phases, and our work will serve to answer questions raised about the element-specific magnetizations using the magnetic x-ray dichroism techniques and interface magnetism in layered structures using polarized neutron reflectometry. Through application of these techniques to understand the materials fabricated in our laboratory, we will employ a tight feedback loop to tailor the magnetic properties on demand. Developing the ability to control magnetic anisotropy is essential for creating the next generation of magnetic storage media (for hard disks, for example), where individual bit sizes have already become smaller than 100nm in the largest dimension. Still smaller bits and higher storage density will require the ability to exquisitely tailor magnetic media properties at the atomic level, the ultimate goal of our study.« less

Few layered MoO3 nano sheets-SWCNT composite thin film as supercapacitor electrode

NASA Astrophysics Data System (ADS)

Dutta, Shibsankar; Akther, Jasim; De, Sukanta

2017-05-01

The increasing demands for clean and renewable energy, the advantages of high power density, long lasting and high efficiency have made Supercapacitor as one of the major emerging energy storage device.The 2D layered metal oxide nanocomposite with SWCNT is the promising candidate for energy storage and conversion. In this work we exfoliate the crystalline bulk MoO3 by simple liquid phase exfoliation to give multi-layer MoO3 dispersed in a suitable solvent. As the electrical conductivity of MoO3 is very low so, the dispersion was used to make hybrid material with SWCNT dispersion by vacuum filtration. The SWCNT-MoO3 composite showed an areal capacitance value of 1290 µF/cm2 at 10 mV/s in PVA-H2 SO4 solid gel electrolyte. This composite based electrode provides an energy density of 0.092 µWh/cm2 and a power density of 9.54 µW/cm2 at 0.01 mA/cm2

Effects of fiber and interfacial layer architectures on the thermoplastic response of metal matrix composites

NASA Technical Reports Server (NTRS)

Pindera, Marek-Jerzy; Freed, Alan D.; Arnold, Steven M.

1992-01-01

Examined here is the effect of fiber and interfacial layer morphologies on thermal fields in metal matrix composites (MMCs). A micromechanics model based on an arbitrarily layered concentric cylinder configuration is used to calculate thermal stress fields in MMCs subjected to spatially uniform temperature changes. The fiber is modelled as a layered material with isotropic or orthotropic elastic layers, whereas the surrounding matrix, including interfacial layers, is treated as a strain-hardening, elastoplastic, von Mises solid with temperature-dependent parameters. The solution to the boundary-value problem of an arbitrarily layered concentric cylinder under the prescribed thermal loading is obtained using the local/global stiffness matrix formulation originally developed for stress analysis of multilayered elastic media. Examples are provided that illustrate how the morphology of the SCS6 silicon carbide fiber and the use of multiple compliant layers at the fiber/matrix interface affect the evolution of residual stresses in SiC/Ti composites during fabrication cool-down.

Passivating overcoat bilayer for multilayer reflective coatings for extreme ultraviolet lithography

DOEpatents

Montcalm, Claude; Stearns, Daniel G.; Vernon, Stephen P.

1999-01-01

A passivating overcoat bilayer is used for multilayer reflective coatings for extreme ultraviolet (EUV) or soft x-ray applications to prevent oxidation and corrosion of the multilayer coating, thereby improving the EUV optical performance. The overcoat bilayer comprises a layer of silicon or beryllium underneath at least one top layer of an elemental or a compound material that resists oxidation and corrosion. Materials for the top layer include carbon, palladium, carbides, borides, nitrides, and oxides. The thicknesses of the two layers that make up the overcoat bilayer are optimized to produce the highest reflectance at the wavelength range of operation. Protective overcoat systems comprising three or more layers are also possible.

Numerical modeling of the effect of heat and mass transfer in porous low-temperature heat insulation in composite material structures on the magnitude of stresses which develop

NASA Astrophysics Data System (ADS)

Kuznetsov, G. V.; Rudzinskaya, N. V.

1997-05-01

The stressed state of multilayer low-temperature heat insulation for a cryogenic fuel tank is considered. Account is taken of heat and mass transfer in foam plastic (the main heat insulation material) occurring at cryogenic temperatures. A method is developed for solving a set of differential equations and boundary conditions. Numerical studies of the main features of these processes are performed. It is established that below 200 K the stresses which arise in foam plastic markedly exceed the ultimate strength for this material. Stresses develop as a result of both a reduction in temperature and a drop in pressure in the foam plastic pores connected with material cooling. On the basis of the results obtained it is established that the combination of thermophysical processes which occur in foam plastic during cooling to cryogenic temperatures leads to changes in the stress-strained state of structure, which should be considered in planning aerospace technology.

Numerical modeling of interaction in the dynamic system "gas-structure" with harmonic motion of the piston in the variable section pipe

NASA Astrophysics Data System (ADS)

Butymova, L. N.; Modorskii, V. Ya.; Petrov, V. Yu.

2016-10-01

The Helmholtz resonator is an instrument to create low-frequency natural oscillations whose wavelength is substantially larger than the dimensions of the resonator itself. Some modern insulating materials are a set of Helmholtz resonators made in the form of a multilayer composite structure with a layer of cells between the carrier layers. The cells have an outlet hole drilled in the support layer. Improving effectiveness of such structures in terms of noise reduction is an urgent task [1 - 7]. It is found that the resonator with a throat of higher surface roughness damps noise more effectively.

Mechanical property degradation of high crystalline SiC fiber–reinforced SiC matrix composite neutron irradiated to ~100 displacements per atom

DOE PAGES

Koyanagi, Takaaki; Nozawa, Takashi; Katoh, Yutai; ...

2017-12-20

For the development of silicon carbide (SiC) materials for next-generation nuclear structural applications, degradation of material properties under intense neutron irradiation is a critical feasibility issue. This paper evaluated the mechanical properties and microstructure of a chemical vapor infiltrated SiC matrix composite, reinforced with a multi-layer SiC/pyrolytic carbon–coated Hi-Nicalon TM Type S SiC fiber, following neutron irradiation at 319 and 629 °C to ~100 displacements per atom. Both the proportional limit stress and ultimate flexural strength were significantly degraded as a result of irradiation at both temperatures. After irradiation at 319 °C, the quasi-ductile fracture behavior of the nonirradiated compositemore » became brittle, a result that was explained by a loss of functionality of the fiber/matrix interface associated with the disappearance of the interphase due to irradiation. Finally, the specimens irradiated at 629 °C showed increased apparent failure strain because the fiber/matrix interphase was weakened by irradiation-induced partial debonding.« less

Multi-layer porous fiber-reinforced composites for implants: in vitro calcium phosphate formation in the presence of bioactive glass.

PubMed

Nganga, Sara; Zhang, Di; Moritz, Niko; Vallittu, Pekka K; Hupa, Leena

2012-11-01

Glass-fiber-reinforced composites (FRCs), based on bifunctional methacrylate resin, have recently shown their potential for use as durable cranioplasty, orthopedic and oral implants. In this study we suggest a multi-component sandwich implant structure with (i) outer layers out of porous FRC, which interface the cortical bone, and (ii) inner layers encompassing bioactive glass granules, which interface with the cancellous bone. The capability of Bioglass(®) 45S5 granules (100-250μm) to induce calcium phosphate formation on the surface of the FRC was explored by immersing the porous FRC-Bioglass laminates in simulated body fluid (SBF) for up to 28d. In both static (agitated) and dynamic conditions, bioactive glass granules induced precipitation of calcium phosphate at the laminate surfaces as confirmed by scanning electron microscopy. The proposed dynamic flow system is useful for the in vitro simulation of bone-like apatite formation on various new porous implant designs containing bioactive glass and implant material degradation. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Mechanical property degradation of high crystalline SiC fiber–reinforced SiC matrix composite neutron irradiated to ~100 displacements per atom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koyanagi, Takaaki; Nozawa, Takashi; Katoh, Yutai

For the development of silicon carbide (SiC) materials for next-generation nuclear structural applications, degradation of material properties under intense neutron irradiation is a critical feasibility issue. This paper evaluated the mechanical properties and microstructure of a chemical vapor infiltrated SiC matrix composite, reinforced with a multi-layer SiC/pyrolytic carbon–coated Hi-Nicalon TM Type S SiC fiber, following neutron irradiation at 319 and 629 °C to ~100 displacements per atom. Both the proportional limit stress and ultimate flexural strength were significantly degraded as a result of irradiation at both temperatures. After irradiation at 319 °C, the quasi-ductile fracture behavior of the nonirradiated compositemore » became brittle, a result that was explained by a loss of functionality of the fiber/matrix interface associated with the disappearance of the interphase due to irradiation. Finally, the specimens irradiated at 629 °C showed increased apparent failure strain because the fiber/matrix interphase was weakened by irradiation-induced partial debonding.« less

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.

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

Design and function of biomimetic multilayer water purification membranes

PubMed Central

Ling, Shengjie; Qin, Zhao; Huang, Wenwen; Cao, Sufeng; Kaplan, David L.; Buehler, Markus J.

2017-01-01

Multilayer architectures in water purification membranes enable increased water throughput, high filter efficiency, and high molecular loading capacity. However, the preparation of membranes with well-organized multilayer structures, starting from the nanoscale to maximize filtration efficiency, remains a challenge. We report a complete strategy to fully realize a novel biomaterial-based multilayer nanoporous membrane via the integration of computational simulation and experimental fabrication. Our comparative computational simulations, based on coarse-grained models of protein nanofibrils and mineral plates, reveal that the multilayer structure can only form with weak interactions between nanofibrils and mineral plates. We demonstrate experimentally that silk nanofibril (SNF) and hydroxyapatite (HAP) can be used to fabricate highly ordered multilayer membranes with nanoporous features by combining protein self-assembly and in situ biomineralization. The production is optimized to be a simple and highly repeatable process that does not require sophisticated equipment and is suitable for scaled production of low-cost water purification membranes. These membranes not only show ultrafast water penetration but also exhibit broad utility and high efficiency of removal and even reuse (in some cases) of contaminants, including heavy metal ions, dyes, proteins, and other nanoparticles in water. Our biomimetic design and synthesis of these functional SNF/HAP materials have established a paradigm that could lead to the large-scale, low-cost production of multilayer materials with broad spectrum and efficiency for water purification, with applications in wastewater treatment, biomedicine, food industry, and the life sciences. PMID:28435877

Design and function of biomimetic multilayer water purification membranes.

PubMed

Ling, Shengjie; Qin, Zhao; Huang, Wenwen; Cao, Sufeng; Kaplan, David L; Buehler, Markus J

2017-04-01

Multilayer architectures in water purification membranes enable increased water throughput, high filter efficiency, and high molecular loading capacity. However, the preparation of membranes with well-organized multilayer structures, starting from the nanoscale to maximize filtration efficiency, remains a challenge. We report a complete strategy to fully realize a novel biomaterial-based multilayer nanoporous membrane via the integration of computational simulation and experimental fabrication. Our comparative computational simulations, based on coarse-grained models of protein nanofibrils and mineral plates, reveal that the multilayer structure can only form with weak interactions between nanofibrils and mineral plates. We demonstrate experimentally that silk nanofibril (SNF) and hydroxyapatite (HAP) can be used to fabricate highly ordered multilayer membranes with nanoporous features by combining protein self-assembly and in situ biomineralization. The production is optimized to be a simple and highly repeatable process that does not require sophisticated equipment and is suitable for scaled production of low-cost water purification membranes. These membranes not only show ultrafast water penetration but also exhibit broad utility and high efficiency of removal and even reuse (in some cases) of contaminants, including heavy metal ions, dyes, proteins, and other nanoparticles in water. Our biomimetic design and synthesis of these functional SNF/HAP materials have established a paradigm that could lead to the large-scale, low-cost production of multilayer materials with broad spectrum and efficiency for water purification, with applications in wastewater treatment, biomedicine, food industry, and the life sciences.

Coherent multilayer crystals and method of making

DOEpatents

Schuller, Ivan K.; Falco, Charles M.

1984-01-01

A new material consisting of a multilayer crystalline structure which is coherent perpendicular to the layers and where each layer is composed of a single crystalline element. The individual layers may vary from 2.ANG. to 100.ANG. or more in thickness.

Reactive multilayer synthesis of hard ceramic foils and films

DOEpatents

Makowiecki, Daniel M.; Holt, Joseph B.

1996-01-01

A method for synthesizing hard ceramic materials such as carbides, borides nd aluminides, particularly in the form of coatings provided on another material so as to improve the wear and abrasion performance of machine tools, for example. The method involves the sputter deposition of alternating layers of reactive metals with layers of carbon, boron, or aluminum and the subsequent reaction of the multilayered structure to produce a dense crystalline ceramic. The material can be coated on a substrate or formed as a foil which can be coild as a tape for later use.

Numerical verification of composite rods theory on multi-story buildings analysis

NASA Astrophysics Data System (ADS)

El-Din Mansour, Alaa; Filatov, Vladimir; Gandzhuntsev, Michael; Ryasny, Nikita

2018-03-01

In the article, a verification proposal of the composite rods theory on the structural analysis of skeletons for high-rise buildings. A testing design model been formed on which horizontal elements been represented by a multilayer cantilever beam operates on transverse bending on which slabs are connected with a moment-non-transferring connections and a multilayer columns represents the vertical elements. Those connections are sufficiently enough to form a shearing action can be approximated by a certain shear forces function, the thing which significantly reduces the overall static indeterminacy degree of the structural model. A system of differential equations describe the operation mechanism of the multilayer rods that solved using the numerical approach of successive approximations method. The proposed methodology to be used while preliminary calculations for the sake of determining the rigidity characteristics of the structure; are needed. In addition, for a qualitative assessment of the results obtained by other methods when performing calculations with the verification aims.

Survival and growth of micro-organisms on air filtration media during initial loading

NASA Astrophysics Data System (ADS)

Kemp, P. C.; Neumeister-Kemp, H. G.; Lysek, G.; Murray, F.

A new type of air filtration medium made from a hygroscopic polymer fibre and constructed in three layers was investigated to measure the survival and growth of micro-organisms on this medium in comparison to a widely used fibreglass medium. Both materials were supplied by the manufacturer and tested "blind". The materials were loaded in an Airotester unit. Micro-organisms were analysed at 2 weekly intervals for 8 weeks by washing filter samples and plating the solution on to agar media and by vital fluorescence microscopy. Filter samples were also weighed to calculate water content and the pH value of the filter material was measured in the wash out eluate. Vital fluorescence microscopy revealed fungi were able to grow on fibreglass medium, but not on the multi-layered polymer. The colony forming unit (CFU) counts did not increase at a steady rate. There was a significant increase on both materials ( P<0.001) during the first 2 weeks which was then followed by a significant decrease in 4 weeks ( P<0.001) but the CFU then significantly increased in 6 weeks ( P<0.05) which were the highest CFU counts during the 2-month trial. There was a significant difference in CFU counts between the filter materials only in week 2 ( P⩽0.001) and week 4 ( P=0.04). Fewer micro-organisms were extracted from the multi-layered polymer than from the fibreglass medium. Fewer fungal species were identified on the multi-layered polymer (nine species) than on the fibreglass medium (13 species). The pH value on the multi-layered polymer was significantly higher than the fibreglass material but only when clean ( P<0.010) and after 2 weeks ( P<0.001). A significantly higher water content on the fibreglass medium ( P<0.001) also indicated a habitat where a wider range of fungal species and bacteria are able to survive. While there was a reduced survival and growth of micro-organisms on the multi-layered polymer material in the initial month of service life, this advantage was cancelled by the supply of nutrients (particulate matter) that were accumulated on the filter materials after 6 weeks.

Ordered organic-organic multilayer growth

DOEpatents

Forrest, Stephen R.; Lunt, Richard R.

2016-04-05

An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

Ordered organic-organic multilayer growth

DOEpatents

Forrest, Stephen R; Lunt, Richard R

2015-01-13

An ordered multilayer crystalline organic thin film structure is formed by depositing at least two layers of thin film crystalline organic materials successively wherein the at least two thin film layers are selected to have their surface energies within .+-.50% of each other, and preferably within .+-.15% of each other, whereby every thin film layer within the multilayer crystalline organic thin film structure exhibit a quasi-epitaxial relationship with the adjacent crystalline organic thin film.

Asymptotic analysis of the shear strain effect on the wave characteristics of a multilayered cylindrical shell filled with fluid

NASA Astrophysics Data System (ADS)

Amenzade, R. Yu.; Kiiko, I. A.

2007-06-01

It is commonly assumed that the theory based on the Kirchhoff hypotheses describes the properties inherent in the wave processes occurring in shells filled with fluids. But there are several new effects that cannot be described by this theory (in particular, the appearance of new types of waves). In this paper, we present a linearized description of axisymmetric wave motion of a perfect incompressible fluid in a multilayered cylindrical shell with allowance for shear strain; the shell is assumed to be infinite and simply supported. This description is aimed at finding new mechanical effects and hence at estimating the influence of the multiple layers and the shear strain on the wave characteristics. In a sense, it generalizes and develops well-known studies of this type. Practice necessitates deriving equations constructed under the assumption that the physical and mechanical properties of the shell material are inhomogeneous along the thickness direction or the shell is multilayered; the development of refined theories (compared with the classical theory based on the Kirchhoff—Love straight normal hypothesis) is also inspired by practice. This is primarily related to the fact that multilayered thin-walled shells made of composite materials are used in various fields of technology. It is of interest to note that, as a result of long evolution, the phenomenon of being multilayered also predominates in living organisms. For example, this is typical of big blood vessels [1] (arteries and veins). In [2], on the basis of a three-dimensional variational principle of mixed type, the equations of motion and physical relations for elastic anisotropic shells rigidly inhomogeneous in the thickness direction are derived under the assumptions of the theory of thin shells and with shear strains taken into account. It is also noted that the case of multilayered shells can be modeled by introducing functions with integrable singularities. When studying wave propagation in deformable shells containing fluid, hydroelasticity problems arise; the solution of such problems is of both theoretical and practical importance. Of topical problems in this field, problems related to pulsating blood flow in big blood vessels [3] (the theory of pulse waves) are worth mentioning. The incentive for such studies is that they can help to understand the normal operation of the blood circulatory system, predict its reaction to variations, and propose methods for artificial intervention. Thus, diagnostics, surgery, and prosthesis are closely related to biomechanics. But the applied value of such problems is not bounded by their applications in hemodynamics. They are also very important in technology because of the wide use of systems of fluid and gas transportation through pipelines with corrosion-resistant coating.

Delamination Analysis of a Multilayered Two-Dimensional Functionally Graded Cantilever Beam

NASA Astrophysics Data System (ADS)

Rizov, V.

2017-11-01

Delamination fracture behaviour of a multilayered two-dimensional functionally graded cantilever beam is analyzed in terms of the strain energy release rate. The beam is made of an arbitrary number of layers. Perfect adhesion is assumed between layers. Each layer has individual thickness and material properties. Besides, the material is two-dimensional functionally graded in the cross-section of each layer. There is a delamination crack located arbitrary between layers. The beam is loaded by a bending moment applied at the free end of the lower crack arm. The upper crack arm is free of stresses. The solution to strain energy release rate derived is applied to investigate the influence of the crack location and the material gradient on the delamination fracture. The results obtained can be used to optimize the multilayered two-dimensional functionally graded beam structure with respect to the delamination fracture behaviour.

Soft X-ray imaging of thick carbon-based materials using the normal incidence multilayer optics.

PubMed

Artyukov, I A; Feschenko, R M; Vinogradov, A V; Bugayev, Ye A; Devizenko, O Y; Kondratenko, V V; Kasyanov, Yu S; Hatano, T; Yamamoto, M; Saveliev, S V

2010-10-01

The high transparency of carbon-containing materials in the spectral region of "carbon window" (lambda approximately 4.5-5nm) introduces new opportunities for various soft X-ray microscopy applications. The development of efficient multilayer coated X-ray optics operating at the wavelengths of about 4.5nm has stimulated a series of our imaging experiments to study thick biological and synthetic objects. Our experimental set-up consisted of a laser plasma X-ray source generated with the 2nd harmonics of Nd-glass laser, scandium-based thin-film filters, Co/C multilayer mirror and X-ray film UF-4. All soft X-ray images were produced with a single nanosecond exposure and demonstrated appropriate absorption contrast and detector-limited spatial resolution. A special attention was paid to the 3D imaging of thick low-density foam materials to be used in design of laser fusion targets.

Coherent multilayer crystals and method of making

DOEpatents

Schuller, I.K.; Falco, C.M.

A new material consisting of a multilayer crystalline structure is described which is coherent perpendicular to the layers and where each layer is composed of a single crystallilne element. The individual layers may vary from 2A to 100A or more in thickness.

Disordered 3 D Multi-layer Graphene Anode Material from CO2 for Sodium-Ion Batteries.

PubMed

Smith, Kassiopeia; Parrish, Riley; Wei, Wei; Liu, Yuzi; Li, Tao; Hu, Yun Hang; Xiong, Hui

2016-06-22

We report the application of disordered 3 D multi-layer graphene, synthesized directly from CO2 gas through a reaction with Li at 550 °C, as an anode for Na-ion batteries (SIBs) toward a sustainable and greener future. The material exhibited a reversible capacity of ∼190 mA h g(-1) with a Coulombic efficiency of 98.5 % at a current density of 15 mA g(-1) . The discharge capacity at higher potentials (>0.2 V vs. Na/Na(+) ) is ascribed to Na-ion adsorption at defect sites, whereas the capacity at low potentials (<0.2 V) is ascribed to intercalation between graphene sheets through electrochemical characterization, Raman spectroscopy, and small-angle X-ray scattering experiments. The disordered multi-layer graphene electrode demonstrated a great rate capability and cyclability. This novel approach to synthesize disordered 3 D multi-layer graphene from CO2 gas makes it attractive not only as an anode material for SIBs but also to mitigate CO2 emission. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Infrared metamaterial by RF magnetron sputtered ZnO/Al:ZnO multilayers

NASA Astrophysics Data System (ADS)

Santiago, Kevin C.; Mundle, Rajeh; White, Curtis; Bahoura, Messaoud; Pradhan, Aswini K.

2018-03-01

Hyperbolic metamaterials create artificial anisotropy using metallic wires suspended in dielectric media or alternating layers of a metal and dielectric (Type I or Type II). In this study we fabricated ZnO/Al:ZnO (AZO) multilayers by the RF magnetron sputtering deposition technique. Our fabricated multilayers satisfy the requirements for a type II hyperbolic metamaterial. The optical response of individual AZO and ZnO films, as well as the multilayered film were investigated via UV-vis-IR transmittance and spectroscopic ellipsometry. The optical response of the multilayered system is calculated using the nonlocal-corrected Effective Medium Approximation (EMA). The spectroscopic ellipsometry data of the multilayered system was modeled using a uniaxial material model and EMA model. Both theoretical and experimental studies validate the fabricated multilayers undergo a hyperbolic transition at a wavelength of 2.2 μm. To our knowledge this is the first AZO/ZnO type II hyperbolic metamaterial system fabricated by magnetron sputtering deposition method.

Artificial Bone and Teeth through Controlled Ice Growth in Colloidal Suspensions

NASA Astrophysics Data System (ADS)

Tomsia, Antoni P.; Saiz, Eduardo; Deville, Sylvain

2007-06-01

The formation of regular patterns is a common feature of many solidification processes involving cast materials. We describe here how regular patterns can be obtained in porous alumina and hydroxyapatite (HAP) by controlling the freezing of ceramic slurries followed by subsequent ice sublimation and sintering, leading to multilayered porous ceramic structures with homogeneous and well-defined architecture. These porous materials can be infiltrated with a second phase of choice to yield biomimetic nacre-like composites with improved mechanical properties, which could be used for artificial bone and teeth applications. Proper control of the solidification patterns provides powerful means of control over the final functional properties. We discuss the relationships between the experimental results, ice growth fundamentals, the physics of ice and the interaction between inert particles and the solidification front during directional freezing.

Artificial Bone and Teeth through Controlled Ice Growth in Colloidal Suspensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tomsia, Antoni P.; Saiz, Eduardo; Deville, Sylvain

2007-06-14

The formation of regular patterns is a common feature of many solidification processes involving cast materials. We describe here how regular patterns can be obtained in porous alumina and hydroxyapatite (HAP) by controlling the freezing of ceramic slurries followed by subsequent ice sublimation and sintering, leading to multilayered porous ceramic structures with homogeneous and well-defined architecture. These porous materials can be infiltrated with a second phase of choice to yield biomimetic nacre-like composites with improved mechanical properties, which could be used for artificial bone and teeth applications. Proper control of the solidification patterns provides powerful means of control over themore » final functional properties. We discuss the relationships between the experimental results, ice growth fundamentals, the physics of ice and the interaction between inert particles and the solidification front during directional freezing.« less

Hierarchical structure graphitic-like/MoS2 film as superlubricity material

NASA Astrophysics Data System (ADS)

Gong, Zhenbin; Jia, Xiaolong; Ma, Wei; Zhang, Bin; Zhang, Junyan

2017-08-01

Friction and wear result in a great amount of energy loss and the invalidation of mechanical parts, thus it is necessary to minimize friction in practical application. In this study, the graphitic-like/MoS2 films with hierarchical structure were synthesized by the combination of pulse current plasma chemical-vapor deposition and medium frequency unbalanced magnetron sputtering in preheated environment. This hierarchical structure composite with multilayer nano sheets endows the films excellent tribological performance, which easily achieves macro superlubricity (friction coefficient ∼0.004) under humid air. Furthermore, it is expected that hierarchical structure of graphitic-like/MoS2 films could match the requirements of large scale, high bear-capacity and wear-resistance of actual working conditions, which could be widely used in the industrial production as a promising superlubricity material.

Heavy metal multilayers for switching of magnetic unit via electrical current without magnetic field, method and applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Qinli; Li, Yufan; Chien, Chia-ling

Provided is an electric-current-controllable magnetic unit, including: a substrate, an electric-current channel disposed on the substrate, the electric-current channel including a composite heavy-metal multilayer comprising at least one heavy-metal; a capping layer disposed over the electric-current channel; and at least one ferromagnetic layer disposed between the electric-current channel and the capping layer.

New Approach to Ultrasonic Spectroscopy Applied to Flywheel Rotors

NASA Technical Reports Server (NTRS)

Harmon, Laura M.; Baaklini, George Y.

2002-01-01

Flywheel energy storage devices comprising multilayered composite rotor systems are being studied extensively for use in the International Space Station. A flywheel system includes the components necessary to store and discharge energy in a rotating mass. The rotor is the complete rotating assembly portion of the flywheel, which is composed primarily of a metallic hub and a composite rim. The rim may contain several concentric composite rings. This article summarizes current ultrasonic spectroscopy research of such composite rings and rims and a flat coupon, which was manufactured to mimic the manufacturing of the rings. Ultrasonic spectroscopy is a nondestructive evaluation (NDE) method for material characterization and defect detection. In the past, a wide bandwidth frequency spectrum created from a narrow ultrasonic signal was analyzed for amplitude and frequency changes. Tucker developed and patented a new approach to ultrasonic spectroscopy. The ultrasonic system employs a continuous swept-sine waveform and performs a fast Fourier transform on the frequency spectrum to create the spectrum resonance spacing domain, or fundamental resonant frequency. Ultrasonic responses from composite flywheel components were analyzed at Glenn to assess this NDE technique for the quality assurance of flywheel applications.

Analyses of Hubble Space Telescope Aluminized-Teflon Multilayer Insulation Blankets Retrieved After 19 Years of Space Exposure

NASA Technical Reports Server (NTRS)

de Groh, Kim K.; Perry, Bruce A.; Mohammed, Jelila S.; Banks, Bruce

2015-01-01

Since its launch in April 1990, the Hubble Space Telescope (HST) has made many important observations from its vantage point in low Earth orbit (LEO). However, as seen during five servicing missions, the outer layer of multilayer insulation (MLI) has become increasingly embrittled and has cracked in many areas. In May 2009, during the 5th servicing mission (called SM4), two MLI blankets were replaced with new insulation and the space-exposed MLI blankets were retrieved for degradation analyses by teams at NASA Glenn Research Center (GRC) and NASA Goddard Space Flight Center (GSFC). The retrieved MLI blankets were from Equipment Bay 8, which received direct sunlight, and Equipment Bay 5, which received grazing sunlight. Each blanket was divided into several regions based on environmental exposure and/or physical appearance. The aluminized-Teflon (DuPont, Wilmington, DE) fluorinated ethylene propylene (Al-FEP) outer layers of the retrieved MLI blankets have been analyzed for changes in optical, physical, and mechanical properties, along with chemical and morphological changes. Pristine and as-retrieved samples (materials) were heat treated to help understand degradation mechanisms. When compared to pristine material, the analyses have shown how the Al-FEP was severely affected by the space environment. Most notably, the Al-FEP was highly embrittled, fracturing like glass at strains of 1 to 8 percent. Across all measured properties, more significant degradation was observed for Bay 8 material as compared to Bay 5 material. This paper reviews the tensile and bend-test properties, density, thickness, solar absorptance, thermal emittance, x-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) elemental composition measurements, surface and crack morphologies, and atomic oxygen erosion yields of the Al-FEP outer layer of the retrieved HST blankets after 19 years of space exposure.

A hermetic and room-temperature wafer bonding technique based on integrated reactive multilayer systems

NASA Astrophysics Data System (ADS)

Braeuer, J.; Gessner, T.

2014-11-01

This paper focuses on direct deposition and patterning of reactive and nano-scale multilayer films at wafer level. These multilayer structures are called integrated reactive material systems (iRMS). In contrast to the typically used nickel (Ni)/ aluminum (Al) systems, in this work we needed to have our total multilayer film thicknesses smaller than 2.5 µm to reduce stress within the multilayer as well as deposition costs. Thus, we introduced new high energetic iRMS. These films were deposited by using alternating magnetron sputtering from high purity Al- and palladium (Pd)-targets to obtain films with a defined Al:Pd atomic ratio. In this paper, we present the result for reaction characteristics and reaction velocities which were up to 72.5 m s-1 for bond frames with lateral dimensions as low as 20 µm. Furthermore, the feasibility of silicon (Si)-Si, Si-glass as well as Si-ceramic hermetic and metallic wafer bonding at room temperature is presented. We show that by using this bond technology, strong (maximum shear strengths of 235 MPa) and hermetically sealed bond interfaces can be achieved without any additional solder material.

X-ray Fluorescence Spectroscopy Study of Coating Thickness and Base Metal Composition

NASA Technical Reports Server (NTRS)

Rolin, T. D.; Leszczuk, Y.

2008-01-01

For electrical, electronic, and electromechanical (EEE) parts to be approved for space use, they must be able to meet safety standards approved by NASA. A fast, reliable, and precise method is needed to make sure these standards are met. Many EEE parts are coated in gold (Au) and nickel (Ni), and the thickness coating is crucial to a part s performance. A nondestructive method that is efficient in measuring coating thickness is x-ray fluorescence (XRF) spectroscopy. The XRF spectrometer is a machine designed to measure layer thickness and composition of single or multilayered samples. By understanding the limitations in the collection of the data by this method, accurate composition and thickness measurements can be obtained for samples with Au and Ni coatings. To understand the limitations of data found, measurements were taken with the XRF spectrometer and compared to true values of standard reference materials (SRM) that were National Institute of Standards and Technology (NIST) traceable. For every sample, six different parameters were varied to understand measurement error: coating/substrate combination, number of layers, counting interval, collimator size, coating thickness, and test area location. Each measurement was taken in accordance with standards set by the American Society for Testing and Materials (ASTM) International Standard B 568.

Microfabricated bragg waveguide

DOEpatents

Fleming, James G.; Lin, Shawn-Yu; Hadley, G. Ronald

2004-10-19

A microfabricated Bragg waveguide of semiconductor-compatible material having a hollow core and a multilayer dielectric cladding can be fabricated by integrated circuit technologies. The microfabricated Bragg waveguide can comprise a hollow channel waveguide or a hollow fiber. The Bragg fiber can be fabricated by coating a sacrificial mandrel or mold with alternating layers of high- and low-refractive-index dielectric materials and then removing the mandrel or mold to leave a hollow tube with a multilayer dielectric cladding. The Bragg channel waveguide can be fabricated by forming a trench embedded in a substrate and coating the inner wall of the trench with a multilayer dielectric cladding. The thicknesses of the alternating layers can be selected to satisfy the condition for minimum radiation loss of the guided wave.

Recent progress in high-mobility thin-film transistors based on multilayer 2D materials

NASA Astrophysics Data System (ADS)

Hong, Young Ki; Liu, Na; Yin, Demin; Hong, Seongin; Kim, Dong Hak; Kim, Sunkook; Choi, Woong; Yoon, Youngki

2017-04-01

Two-dimensional (2D) layered semiconductors are emerging as promising candidates for next-generation thin-film electronics because of their high mobility, relatively large bandgap, low-power switching, and the availability of large-area growth methods. Thin-film transistors (TFTs) based on multilayer transition metal dichalcogenides or black phosphorus offer unique opportunities for next-generation electronic and optoelectronic devices. Here, we review recent progress in high-mobility transistors based on multilayer 2D semiconductors. We describe the theoretical background on characterizing methods of TFT performance and material properties, followed by their applications in flexible, transparent, and optoelectronic devices. Finally, we highlight some of the methods used in metal-semiconductor contacts, hybrid structures, heterostructures, and chemical doping to improve device performance.

Tailoring graphene layer-to-layer growth

NASA Astrophysics Data System (ADS)

Li, Yongtao; Wu, Bin; Guo, Wei; Wang, Lifeng; Li, Jingbo; Liu, Yunqi

2017-06-01

A layered material grown between a substrate and the upper layer involves complex interactions and a confined reaction space, representing an unusual growth mode. Here, we show multi-layer graphene domains grown on liquid or solid Cu by the chemical vapor deposition method via this ‘double-substrate’ mode. We demonstrate the interlayer-induced coupling effect on the twist angle in bi- and multi-layer graphene. We discover dramatic growth disunity for different graphene layers, which is explained by the ideas of a chemical ‘gate’ and a material transport process within a confined space. These key results lead to a consistent framework for understanding the dynamic evolution of multi-layered graphene flakes and tailoring the layer-to-layer growth for practical applications.

Nanostructure multilayer dielectric materials for capacitors and insulators

DOEpatents

Barbee, Jr., Troy W.; Johnson, Gary W.

1998-04-21

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

Nanostructure multilayer dielectric materials for capacitors and insulators

DOEpatents

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

1998-04-21

A capacitor is formed of at least two metal conductors having a multilayer dielectric and opposite dielectric-conductor interface layers in between. The multilayer dielectric includes many alternating layers of amorphous zirconium oxide (ZrO{sub 2}) and alumina (Al{sub 2}O{sub 3}). The dielectric-conductor interface layers are engineered for increased voltage breakdown and extended service life. The local interfacial work function is increased to reduce charge injection and thus increase breakdown voltage. Proper material choices can prevent electrochemical reactions and diffusion between the conductor and dielectric. Physical vapor deposition is used to deposit the zirconium oxide (ZrO{sub 2}) and alumina (Al{sub 2}O{sub 3}) in alternating layers to form a nano-laminate. 1 fig.

Solution of the Eshelby problem in gradient elasticity for multilayer spherical inclusions

NASA Astrophysics Data System (ADS)

Volkov-Bogorodskii, D. B.; Lurie, S. A.

2016-03-01

We consider gradient models of elasticity which permit taking into account the characteristic scale parameters of the material. We prove the Papkovich-Neuber theorems, which determine the general form of the gradient solution and the structure of scale effects. We derive the Eshelby integral formula for the gradient moduli of elasticity, which plays the role of the closing equation in the self-consistent three-phase method. In the gradient theory of deformations, we consider the fundamental Eshelby-Christensen problem of determining the effective elastic properties of dispersed composites with spherical inclusions; the exact solution of this problem for classical models was obtained in 1976. This paper is the first to present the exact analytical solution of the Eshelby-Christensen problem for the gradient theory, which permits estimating the influence of scale effects on the stress state and the effective properties of the dispersed composites under study.We also analyze the influence of scale factors.

High-performance axicon lenses based on high-contrast, multilayer gratings

NASA Astrophysics Data System (ADS)

Doshay, Sage; Sell, David; Yang, Jianji; Yang, Rui; Fan, Jonathan A.

2018-01-01

Axicon lenses are versatile optical elements that can convert Gaussian beams to Bessel-like beams. In this letter, we demonstrate that axicons operating with high efficiencies and at large angles can be produced using high-contrast, multilayer gratings made from silicon. Efficient beam deflection of incident monochromatic light is enabled by higher-order optical modes in the silicon structure. Compared to diffractive devices made from low-contrast materials such as silicon dioxide, our multilayer devices have a relatively low spatial profile, reducing shadowing effects and enabling high efficiencies at large deflection angles. In addition, the feature sizes of these structures are relatively large, making the fabrication of near-infrared devices accessible with conventional optical lithography. Experimental lenses with deflection angles as large as 40° display field profiles that agree well with theory. Our concept can be used to design optical elements that produce higher-order Bessel-like beams, and the combination of high-contrast materials with multilayer architectures will more generally enable new classes of diffractive photonic structures.

Observation of van Hove Singularities in Twisted Silicene Multilayers

PubMed Central

2016-01-01

Interlayer interactions perturb the electronic structure of two-dimensional materials and lead to new physical phenomena, such as van Hove singularities and Hofstadter’s butterfly pattern. Silicene, the recently discovered two-dimensional form of silicon, is quite unique, in that silicon atoms adopt competing sp2 and sp3 hybridization states leading to a low-buckled structure promising relatively strong interlayer interaction. In multilayer silicene, the stacking order provides an important yet rarely explored degree of freedom for tuning its electronic structures through manipulating interlayer coupling. Here, we report the emergence of van Hove singularities in the multilayer silicene created by an interlayer rotation. We demonstrate that even a large-angle rotation (>20°) between stacked silicene layers can generate a Moiré pattern and van Hove singularities due to the strong interlayer coupling in multilayer silicene. Our study suggests an intriguing method for expanding the tunability of the electronic structure for electronic applications in this two-dimensional material. PMID:27610412

Multilayered Electromagnetic Interference Shielding Structures for Suppressing Magnetic Field Coupling

NASA Astrophysics Data System (ADS)

Watanabe, Atom O.; Raj, Pulugurtha Markondeya; Wong, Denny; Mullapudi, Ravi; Tummala, Rao

2018-05-01

Control of electromagnetic interference (EMI) represents a major challenge for emerging consumer electronics, the Internet of Things, automotive electronics, and wireless communication systems. This paper discusses innovative EMI shielding materials and structures that offer higher shielding effectiveness compared with copper. To create high shielding effectiveness in the frequency range of 1 MHz to 100 MHz, multilayered shielding topologies with electrically conductive and nanomagnetic materials were modeled, designed, fabricated, and characterized. In addition, suppression of out-of-plane and in-plane magnetic-field coupling noise with these structures is compared with that of traditional single-layer copper or nickel-iron films. Compared with single-layered copper shields, multilayered structures consisting of copper, nickel-iron, and titanium showed a 3.9 times increase in shielding effectiveness in suppressing out-of-plane or vertically coupled noise and 1.3 times increase in lateral coupling. The superiority of multilayered thin-film shields over conventional shielding enables greater design flexibility, higher shielding effectiveness, and further miniaturization of emerging radiofrequency (RF) and power modules.

Active multilayered capsules for in vivo bone formation

PubMed Central

Facca, S.; Cortez, C.; Mendoza-Palomares, C.; Messadeq, N.; Dierich, A.; Johnston, A. P. R.; Mainard, D.; Voegel, J.-C.; Caruso, F.; Benkirane-Jessel, N.

2010-01-01

Interest in the development of new sources of transplantable materials for the treatment of injury or disease has led to the convergence of tissue engineering with stem cell technology. Bone and joint disorders are expected to benefit from this new technology because of the low self-regenerating capacity of bone matrix secreting cells. Herein, the differentiation of stem cells to bone cells using active multilayered capsules is presented. The capsules are composed of poly-L-glutamic acid and poly-L-lysine with active growth factors embedded into the multilayered film. The bone induction from these active capsules incubated with embryonic stem cells was demonstrated in vitro. Herein, we report the unique demonstration of a multilayered capsule-based delivery system for inducing bone formation in vivo. This strategy is an alternative approach for in vivo bone formation. Strategies using simple chemistry to control complex biological processes would be particularly powerful, as they make production of therapeutic materials simpler and more easily controlled. PMID:20160118

Tribological Performance of Ni3Al Matrix Self-Lubricating Composites Containing Multilayer Graphene and Ti3SiC2 at Elevated Temperatures

NASA Astrophysics Data System (ADS)

Yan, Zhao; Shi, Xiaoliang; Huang, Yuchun; Deng, Xiaobin; Yang, Kang; Liu, Xiyao

2017-09-01

The application of Ni3Al-based alloy (NA) in the field of aerospace was limited by its poor tribological properties. For improving the tribological performance of NA, multilayer graphene (MLG) and Ti3SiC2 were added in Ni3Al matrix composites. Tribological behavior of Ni3Al matrix composites containing 1.5 wt.% MLG and 10 wt.% Ti3SiC2 (NMT) against Si3N4 ball at 12 N-0.2 m/s from 25 to 750 °C was investigated. The results showed that NMT exhibited the excellent tribological behavior [lower friction coefficients (0.26-0.57) and less wear resistance (3.1-6.5 × 10-6 mm3 N-1 m-1)] due to synergetic effect of MLG and Ti3SiC2 over a wide temperature range from 25 to 750 °C. At 25-350 °C, part of MLG enriched on worn surface could play a role in reducing friction and improving wear resistance. At 350-550 °C, although MLG gradually lost the lubricating properties, the partial decomposition of Ti3SiC2 could continually improve the tribological properties of NMT. At 550-750 °C, Ti3SiC2 on worn surface was oxidized to form lubricating film, while Ti3SiC2 in the subsurface played an important role in supporting the film, resulting in the excellent high-temperature tribological performance. The research had good guiding significance for the preparation of wide temperature range self-lubricating material and the study of synergetic effect of complex solid lubricants.

Bimetallic alloy electrocatalysts with multilayered platinum-skin surfaces

DOEpatents

Stamenkovic, Vojislav R.; Wang, Chao; Markovic, Nenad M.

2016-01-26

Compositions and methods of preparing a bimetallic alloy having enhanced electrocatalytic properties are provided. The composition comprises a PtNi substrate having a surface layer, a near-surface layer, and an inner layer, where the surface layer comprises a nickel-depleted composition, such that the surface layer comprises a platinum skin having at least one atomic layer of platinum.

All-Dielectric Multilayer Cylindrical Structures for Invisibility Cloaking

PubMed Central

Mirzaei, Ali; Miroshnichenko, Andrey E.; Shadrivov, Ilya V.; Kivshar, Yuri S.

2015-01-01

We study optical response of all-dielectric multilayer structures and demonstrate that the total scattering of such structures can be suppressed leading to optimal invisibility cloaking. We use experimental material data and a genetic algorithm to reduce the total scattering by adjusting the material and thickness of various layers for several types of dielectric cores at telecommunication wavelengths. Our approach demonstrates 80-fold suppression of the total scattering cross-section by employing just a few dielectric layers. PMID:25858295

Layer-by-layer design method for soft-X-ray multilayers

NASA Technical Reports Server (NTRS)

Yamamoto, Masaki; Namioka, Takeshi

1992-01-01

A new design method effective for a nontransparent system has been developed for soft-X-ray multilayers with the aid of graphic representation of the complex amplitude reflectance in a Gaussian plane. The method provides an effective means of attaining the absolute maximum reflectance on a layer-by-layer basis and also gives clear insight into the evolution of the amplitude reflectance on a multilayer as it builds up. An optical criterion is derived for the selection of a proper pair of materials needed for designing a high-reflectance multilayer. Some examples are given to illustrate the usefulness of this design method.

Strain Rate and Anisotropic Microstructure Dependent Mechanical Behaviors of Silkworm Cocoon Shells

PubMed Central

Xu, Jun; Zhang, Wen; Gao, Xiang; Meng, Wanlin; Guan, Juan

2016-01-01

Silkworm cocoons are multi-layered composite structures comprised of high strength silk fiber and sericin, and their mechanical properties have been naturally selected to protect pupas during metamorphosis from various types of external attacks. The present study attempts to gain a comprehensive understanding of the mechanical properties of cocoon shell materials from wild silkworm species Antheraea pernyi under dynamic loading rates. Five dynamic strain rates from 0.00625 s-1 to 12.5 s-1 are tested to show the strain rate sensitivity of the cocoon shell material. In the meantime, the anisotropy of the cocoon shell is considered and the cocoon shell specimens are cut along 0°, 45° and 90° orientation to the short axis of cocoons. Typical mechanical properties including Young’s modulus, yield strength, ultimate strength and ultimate strain are extracted and analyzed from the stress-strain curves. Furthermore, the fracture morphologies of the cocoon shell specimens are observed under scanning electron microscopy to help understand the relationship between the mechanical properties and the microstructures of the cocoon material. A discussion on the dynamic strain rate effect on the mechanical properties of cocoon shell material is followed by fitting our experimental results to two previous models, and the effect could be well explained. We also compare natural and dried cocoon materials for the dynamic strain rate effect and interestingly the dried cocoon shells show better overall mechanical properties. This study provides a different perspective on the mechanical properties of cocoon material as a composite material, and provides some insight for bio-inspired engineering materials. PMID:26939063

SiC/Mg multilayer coatings for SCORE coronagraph: long term stability analysis

NASA Astrophysics Data System (ADS)

Pelizzo, Maria Guglielmina; Fineschi, Silvano; Zuppella, Paola; Corso, Alain Jody; Windt, David L.; Nicolosi, Piergiorgio

2011-10-01

SiC/Mg multilayers have been used as coatings of the Sounding-rocket CORonagraphic Experiment (SCORE) telescope mirrors launched during the NASA HERSCHEL program. This materials couple has been largely studied by researchers since it provides higher performances than a standard Mo/Si multilayer; the SCORE mirrors show in fact a peak reflectance of around 40% at HeII 30.4 nm. Nevertheless, long term stability of this coating is an open problem. A study on the aging and stability of this multilayer has been carried on. SiC/Mg multilayer samples characterized by different structural parameters have been deposited. They have been measured just after deposition and four years later to verify degradation based on natural aging. Experimental results and analysis are presented.

Range and stability of structural colors generated by Morpho-inspired color reflectors.

PubMed

Chung, Kyungjae; Shin, Jung H

2013-05-01

The range and stability of structural colors generated by Morpho-inspired color reflectors are investigated. We find that despite the internal randomness of such structures that gives rise to their Morpho-like angle-independent iridescence, their colors under ambient lighting condition can be predicted by simple transfer-matrix calculations of corresponding planar multilayer structures. By calculating the possible range of colors generated by multilayers of different structures and material combinations using such transfer-matrix methods, we find that low-refractive index multilayers with intrastructure absorption, such as the melanin-containing chitin/air multilayer structure from the Morpho butterflies, can provide not only the most pure structural colors with the largest color gamut, but also the highest stability of color against variations in multilayer structure.

Evaluation of different strategies for quantitative depth profile analysis of Cu/NiCu layers and multilayers via pulsed glow discharge - Time of flight mass spectrometry

NASA Astrophysics Data System (ADS)

Muñiz, Rocío; Lobo, Lara; Németh, Katalin; Péter, László; Pereiro, Rosario

2017-09-01

There is still a lack of approaches for quantitative depth-profiling when dealing with glow discharges (GD) coupled to mass spectrometric detection. The purpose of this work is to develop quantification procedures using pulsed GD (PGD) - time of flight mass spectrometry. In particular, research was focused towards the depth profile analysis of Cu/NiCu nanolayers and multilayers electrodeposited on Si wafers. PGDs are characterized by three different regions due to the temporal application of power: prepeak, plateau and afterglow. This last region is the most sensitive and so it is convenient for quantitative analysis of minor components; however, major elements are often saturated, even at 30 W of applied radiofrequency power for these particular samples. For such cases, we have investigated two strategies based on a multimatrix calibration procedure: (i) using the afterglow region for all the sample components except for the major element (Cu) that was analyzed in the plateau, and (ii) using the afterglow region for all the elements measuring the ArCu signal instead of Cu. Seven homogeneous certified reference materials containing Si, Cr, Fe, Co, Ni and Cu have been used for quantification. Quantitative depth profiles obtained with these two strategies for samples containing 3 or 6 multilayers (of a few tens of nanometers each layer) were in agreement with the expected values, both in terms of thickness and composition of the layers.

Reactive multilayer synthesis of hard ceramic foils and films

DOEpatents

Makowiecki, D.M.; Holt, J.B.

1996-02-13

A method is disclosed for synthesizing hard ceramic materials such as carbides, borides and aluminides, particularly in the form of coatings provided on another material so as to improve the wear and abrasion performance of machine tools, for example. The method involves the sputter deposition of alternating layers of reactive metals with layers of carbon, boron, or aluminum and the subsequent reaction of the multilayered structure to produce a dense crystalline ceramic. The material can be coated on a substrate or formed as a foil which can be coiled as a tape for later use.

Performance of resin transfer molded multiaxial warp knit composites

NASA Technical Reports Server (NTRS)

Dexter, H. Benson; Hasko, Gregory H.

1993-01-01

Composite materials that are subjected to complex loads have traditionally been fabricated with multidirectionally oriented prepreg tape materials. Some of the problems associated with this type of construction include low delamination resistance, poor out-of-plane strength, and labor intensive fabrication processes. Textile reinforced composites with through-the-thickness reinforcement have the potential to solve some of these problems. Recently, a relatively new class of noncrimp fabrics designated as multiaxial warp knits have been developed to minimize some of the high cost and damage tolerance concerns. Multiple stacks of warp knit fabrics can be knitted or stitched together to reduce layup labor cost. The through-the-thickness reinforcement can provide significant improvements in damage tolerance and out-of-plane strength. Multilayer knitted/stitched preforms, in conjunction with resin transfer molding (RTM), offer potential for significant cost savings in fabrication of primary aircraft structures. The objectives of this investigation were to conduct RTM processing studies and to characterize the mechanical behavior of composites reinforced with three multiaxial warp knit fabrics. The three fabrics investigated were produced by Hexcel and Milliken in the United States, and Saerbeck in Germany. Two resin systems, British Petroleum E9O5L and 3M PR 500, were characterized for RTM processing. The performance of Hexcel and Milliken quasi-isotropic knitted fabrics are compared to conventional prepreg tape laminates. The performance of the Saerbeck fabric is compared to uniweave wing skin layups being investigated by Douglas Aircraft Company in the NASA Advanced Composites Technology (ACT) program. Tests conducted include tension, open hole tension, compression, open hole compression, and compression after impact. The effects of fabric defects, such as misaligned fibers and gaps between tows, on material performance are also discussed. Estimated material and labor cost savings are projected for the Saerbeck fabric as compared to uniweave fabric currently being used by Douglas in the NASA ACT wing development program.

Mechanical Behaviour of 3D Multi-layer Braided Composites: Experimental, Numerical and Theoretical Study

NASA Astrophysics Data System (ADS)

Deng, Jian; Zhou, Guangming; Ji, Le; Wang, Xiaopei

2017-12-01

Mechanical properties and failure mechanisms of a newly designed 3D multi-layer braided composites are evaluated by experimental, numerical and theoretical studies. The microstructure of the composites is introduced. The unit cell technique is employed to address the periodic arrangement of the structure. The volume averaging method is used in theoretical solutions while FEM with reasonable periodic boundary conditions and meshing technique in numerical simulations. Experimental studies are also conducted to verify the feasibility of the proposed models. Predicted elastic properties agree well with the experimental data, indicating the feasibility of the proposed models. Numerical evaluation is more accurate than theoretical assessment. Deformations and stress distributions of the unit cell under tension shows displacement and traction continuity, guaranteeing the rationality of the applied periodic boundary conditions. Although compression and tension modulus are close, the compressive strength only reaches 70% of the tension strength. This indicates that the composites can be weakened in compressive loading. Additionally, by analysing the micrograph of fracture faces and strain-stress curves, a brittle failure mechanism is observed both in composites under tension and compression.

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 for only a small number of materials, and even less recipes exist for concurrent etching of more than one element so a fully material specific process needs to be developed. In this paper, sectioning of WSi2/Si multilayers for MLL fabrication using fluorinated gases is investigated. The main goals were to demonstrate the feasibility of this technique, achievement of high anisotropy, adequate sidewall roughness control and high etching rates. We note that this development for MLL sidewalls should be distinguished from work on improving aspect ratios in traditional Fresnel zone plates. Aspect ratios for MLL sidewalls are not similarly constrained.

Sound transmission through lined, composite panel structures: Transversely isotropic poro-elastic model

NASA Astrophysics Data System (ADS)

Kim, Jeong-Woo

A joint experimental and analytical investigation of the sound transmission loss (STL) and two-dimensional free wave propagation in composite sandwich panels is presented here. An existing panel, a Nomex honeycomb sandwich panel, was studied in detail. For the purpose of understanding the typical behavior of sandwich panels, a composite structure comprising two aluminum sheets with a relatively soft, poro-elastic foam core was also constructed and studied. The cores of both panels were modeled using an anisotropic (transversely isotropic) poro-elastic material theory. Several estimation methods were used to obtain the material properties of the honeycomb core and the skin plates to be used in the numerical calculations. Appropriate values selected from among the estimates were used in the STL and free wave propagation models. The prediction model was then verified in two ways: first, the calculated wave speeds and STL of a single poro-elastic layer were numerically verified by comparison with the predictions of a previously developed isotropic model. Secondly, to physically validate the transversely isotropic model, the measured STL and the phase speeds of the sandwich panels were compared with their predicted values. To analyze the actual treatment of a fuselage structure, multi-layered configurations, including a honeycomb panel and several layers such as air gaps, acoustic blankets and membrane partitions, were formulated. Then, to find the optimal solution for improving the sound barrier performance of an actual fuselage system, air layer depth and glass fiber lining effects were investigated by using these multi-layer models. By using the free wave propagation model, the first anti-symmetric and symmetric modes of the sandwich panels were characterized to allow the identification of the coincidence frequencies of the sandwich panel. The behavior of the STL could then be clearly explained by comparison with the free wave propagation solutions. By performing a parameter study based both on the STL and free wave propagation speeds, the mass, stiffness and damping-controlled regions of the STL were identified. The structural factors that can be adjusted to improve STL performance were also identified.

Localized temperature stability in Low Temperature Cofired Ceramics (LTCC).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Steven Xunhu; Hsieh, Lung-Hwa.

2012-04-01

The base dielectrics of commercial low temperature cofired ceramics (LTCC) systems have a temperature coefficient of resonant frequency ({tau}{sub f}) in the range -50 {approx} -80 ppm/C. In this research we explored a method to realize zero or near zero {tau}{sub f} resonators by incorporating {tau}{sub f} compensating materials locally into a multilayer LTCC structure. To select composition for {tau}{sub f} adjustment, {tau}{sub f} compensating materials with different amount of titanates were formulated, synthesized, and characterized. Chemical interactions and physical compatibility between the {tau}{sub f} modifiers and the host LTCC dielectrics were investigated. Studies on stripline (SL) resonator panels withmore » multiple compensating dielectrics revealed that: 1) compositions using SrTiO{sub 3} provide the largest {tau}{sub f} adjustment among titanates, 2) the {tau}{sub f} compensation is proportional to the amount of SrTiO{sub 3} in compensating materials, as well as the thickness of the compensating layer, and 3) the most effective {tau}{sub f} compensation is achieved when the compensating dielectric is integrated next to the SL. Using the effective dielectric constant of a heterogeneous layered dielectric structure, results from Method of Momentum (MoM) electromagnetic simulations are consistent with the experimental observations.« less

Multilayer Pressure Vessel Materials Testing and Analysis Phase 2

NASA Technical Reports Server (NTRS)

Popelar, Carl F.; Cardinal, Joseph W.

2014-01-01

To provide NASA with a suite of materials strength, fracture toughness and crack growth rate test results for use in remaining life calculations for the vessels described above, Southwest Research Institute® (SwRI®) was contracted in two phases to obtain relevant material property data from a representative vessel. An initial characterization of the strength, fracture and fatigue crack growth properties was performed in Phase 1. Based on the results and recommendations of Phase 1, a more extensive material property characterization effort was developed in this Phase 2 effort. This Phase 2 characterization included additional strength, fracture and fatigue crack growth of the multilayer vessel and head materials. In addition, some more limited characterization of the welds and heat affected zones (HAZs) were performed. This report

Fracture Mechanics of Transverse Cracks and Edge Delamination in Graphite-Epoxy Composite Laminates.

DTIC Science & Technology

1982-03-01

Fracture failure in multi-layer epoxy-based composite laminates seldom begins with breaking of the load-carrying reinforcing fibers. Rather, smeall...often observed sub-laminate fracture mudes in, e.g., glass-epoxy and graph- ite-epoxy composite laminates. Although these matrix-dominated crackings...the uicrostructures of any given fibrous composite , fracture analysis of sub-laminate cracks based on micro leanie [I Is almost Impossible If not

Mono vs multilayer fibronectin coatings on polar/hydrophobic/ionic polyurethanes: Altering surface interactions with human monocytes.

PubMed

Gossart, Audrey; Battiston, Kyle G; Gand, Adeline; Pauthe, Emmanuel; Santerre, J Paul

2018-01-15

Monocyte interactions with materials that are biofunctionalized with fibronectin (Fn) are of interest because of the documented literature which associates this protein with white blood cell function at implant sites. A degradable-polar hydrophobic ionic polyurethane (D-PHI), has been reported to promote an anti-inflammatory response from human monocytes. The aim of the current work was to study the influence of intrinsic D-PHI material chemistry on Fn adsorption (mono and multi-layer structures), and to investigate the influence of such chemistry on the structural state of the Fn, as well as the latter's influence on the activity of human monocytes on the protein coated substrates. Significant differences in Fn adsorption, surface hydrophobicity and the availability of defined peptide sequences (N terminal, C terminal or Cell Binding Domain) for the Fn in mono vs multilayer structures were observed as a function of the changes in intrinsic material chemistry. A D-PHI-formulated polyurethane substrate with subtle changes in anionic and hydrophobic domain content relative to the polar non-ionic urethane/carbonate groups within the polymer matrix promoted the lowest activation of monocytes, in the presence of multi-layer Fn constructs. These results highlight the importance of chemical heterogeneity as a design parameter for biomaterial surfaces, and establishes a desired strategy for controlling human monocyte activity at the surface of devices, when these are coated with multi-layer Fn structures. The latter is an important step towards functionalizing the materials with multi-layer protein drug carriers as interventional therapeutic agents. The control of the behavior of monocytes, especially migration and activation, is of crucial interest to modulate the inflammatory response at the site of implanted biomaterial. Several studies report the influence of adsorbed serum proteins on the behavior of monocytes on biomaterials. However, few studies show the influence of surface chemical group distribution on the controlled adsorption and the subsequent induced conformation- of mono versus multi-layer assembled structures generated from specific proteins implicated in wound repair. The current research considered the role of Fn adsorption and conformation in thin films while interacting with the intrinsic chemistry of segmented block polyurethanes; and the influence of the former on modulation and activation of human monocytes. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Perpendicular magnetic anisotropy of Pd-Co alloy films and related multilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsunashima, S.; Nagase, K.; Nakamura, K.

1989-09-01

Magnetic anisotropy of Pd/sub x/Co/sub 1-x/alloy films and Pd/sub 67/Co/sub 33/, Pd/sub 67/Co/sub 33/, Pd/sub 67/Co/sub 33//Cu multilayers are investigated. Vacuum deposited PdCo alloy films exhibit uniaxial anisotropy Ku with the easy axis perpendicular to the film plane. The maximum Ku is about 5X10/sup 6/erg/cm/sup 3/ for x=0.35 to 0.50. Compositional dependence of Ku is similar to that of the magnetostriction constant {lambda}/sub 111/, which suggests magnetostrictive origin. In multilayer films, PdCo/Pt and PdCo/Pd showed positive Ku while PdCo/Cu showed negative.

Nano-electromechanical switch-CMOS hybrid technology and its applications.

PubMed

Lee, B H; Hwang, H J; Cho, C H; Lim, S K; Lee, S Y; Hwang, H

2011-01-01

Si-based CMOS technology is facing a serious challenge in terms of power consumption and variability. The increasing costs associated with physical scaling have motivated a search for alternative approaches. Hybridization of nano-electromechanical (NEM)-switch and Si-based CMOS devices has shown a theoretical feasibility for power management, but a huge technical gap must be bridged before a nanoscale NEM switch can be realized due to insufficient material development and the limited understanding of its reliability characteristics. These authors propose the use of a multilayer graphene as a nanoscale cantilever material for a nanoscale NEM switchwith dimensions comparable to those of the state-of-the-art Si-based CMOS devices. The optimal thickness for the multilayer graphene (about five layers) is suggested based on an analytical model. Multilayer graphene can provide the highest Young's modulus among the known electrode materials and a yielding strength that allows more than 15% bending. Further research on material screening and device integration is needed, however, to realize the promises of the hybridization of NEM-switch and Si-based CMOS devices.

Analysis of Counterfeit Coated Tablets and Multi-Layer Packaging Materials Using Infrared Microspectroscopic Imaging.

PubMed

Winner, Taryn L; Lanzarotta, Adam; Sommer, André J

2016-06-01

An effective method for detecting and characterizing counterfeit finished dosage forms and packaging materials is described in this study. Using attenuated total internal reflection Fourier transform infrared spectroscopic imaging, suspect tablet coating and core formulations as well as multi-layered foil safety seals, bottle labels, and cigarette tear tapes were analyzed and compared directly with those of a stored authentic product. The approach was effective for obtaining molecular information from structures as small as 6 μm.

Approximate Green's function methods for HZE transport in multilayered materials

NASA Technical Reports Server (NTRS)

Wilson, John W.; Badavi, Francis F.; Shinn, Judy L.; Costen, Robert C.

1993-01-01

A nonperturbative analytic solution of the high charge and energy (HZE) Green's function is used to implement a computer code for laboratory ion beam transport in multilayered materials. The code is established to operate on the Langley nuclear fragmentation model used in engineering applications. Computational procedures are established to generate linear energy transfer (LET) distributions for a specified ion beam and target for comparison with experimental measurements. The code was found to be highly efficient and compared well with the perturbation approximation.

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.

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.

Material property for designing, analyzing, and fabricating space structures

NASA Technical Reports Server (NTRS)

Kolkailah, Faysal A.

1991-01-01

An analytical study was made of plasma assisted bullet projectile. The finite element analysis and the micro-macromechanic analysis was applied to an optimum design technique for the multilayered graphite-epoxy composite projectile that will achieve hypervelocity of 6 to 10 Km/s. The feasibility was determined of dialectics to monitor cure of graphite-epoxies. Several panels were fabricated, cured, and tested with encouraging results of monitoring the cure of graphite-epoxies. The optimum cure process for large structures was determined. Different orientation were used and three different curing cycles were employed. A uniaxial tensile test was performed on all specimens. The optimum orientation with the optimum cure cycle were concluded.

Analysis of selected materials flown on interior locations of the Long Duration Exposure Facility

NASA Technical Reports Server (NTRS)

Smith, H. A.; Nelson, K. M.; Eash, D.; Pippin, H. G.

1994-01-01

This report documents the post-flight condition of selected hardware taken from interior locations on the Long Duration Exposure Facility (LDEF). This hardware was generally in excellent condition. Outgassing data is presented for heat shrink tubing and fiberglass composite shims. Variation in total mass loss (TML) values for heat shrink tubing were correlated with location. Nylon grommets were evaluated for mechanical integrity; slight embrittlement was observed for flight specimens. Multi-layer insulation blankets, wire bundles, and paints in non-exposed interior locations were all in visibly good condition. Silicon-containing contaminant films were observed on silver-coated hex nuts at the space- and Earth-end interior locations.

Magnetic and electrical control of engineered materials

DOEpatents

Schuller, Ivan K.; de La Venta Granda, Jose; Wang, Siming; Ramirez, Gabriel; Erekhinskiy, Mikhail; Sharoni, Amos

2016-08-16

Methods, systems, and devices are disclosed for controlling the magnetic and electrical properties of materials. In one aspect, a multi-layer structure includes a first layer comprising a ferromagnetic or ferrimagnetic material, and a second layer positioned within the multi-layer structure such that a first surface of the first layer is in direct physical contact with a second surface of the second layer. The second layer includes a material that undergoes structural phase transitions and metal-insulator transitions upon experiencing a change in temperature. One or both of the first and second layers are structured to allow a structural phase change associated with the second layer cause a change magnetic properties of the first layer.

Size-dependent magnetic properties of FeGaB/Al2O3 multilayer micro-islands

NASA Astrophysics Data System (ADS)

Wang, X.; Gao, Y.; Chen, H.; Chen, Y.; Liang, X.; Lin, W.; Sun, N. X.

2018-06-01

Recently, micrometer-size patterned magnetic materials have been widely used in MEMS devices. However, the self-demagnetizing action is significantly influencing the performance of the magnetic materials in many MEMS devices. Here, we report an experimental study on the magnetic properties of the patterned micro-scale FeGaB/Al2O3 multilayers. Ferromagnetic hysteresis loop, ferromagnetic resonance (FMR), permeability and domain behavior have been demonstrated by complementary techniques. Magnetic annealing was used to enhance the performance of magnetic multilayers. The comparisons among micro-islands with different sizes in the range of 200 μm ∼ 500 μm as well as full film show a marked influence of size-effect, the exchange coupling effect, and the different domain structures inside the islands.

Rate- and Temperature-Dependent Material Behavior of a Multilayer Polymer Battery Separator

NASA Astrophysics Data System (ADS)

Avdeev, Ilya; Martinsen, Michael; Francis, Alex

2014-01-01

Designing battery packs for safety in automotive applications requires multiscale modeling, as macroscopic deformations due to impact cause the mechanical failure of individual cells on a sub-millimeter level. The separator material plays a critical role in this process, as the thinning or perforating of the separator can lead to thermal runaway and catastrophic failure of an entire battery pack. The electrochemical properties of various polymer separators have been extensively investigated; however, the dependency of mechanical properties of these thin films on various factors, such as high temperature and strain rate, has not been sufficiently characterized. In this study, the macroscopic mechanical properties of a multilayer polymer thin film used as a battery separator are studied experimentally at various temperatures, strain rates, and solvent saturations. Due to the anisotropy of the material, material testing was conducted in two perpendicular directions (machine and transverse directions). Material samples were tested in both dry and saturated conditions at several temperatures, and it was found that temperature and strain rate have a nearly linear effect on the stress experienced by the material. Additionally, saturating the separator material in a common lithium-ion solvent had softened it and had a positive effect on its toughness. The experimental results obtained in this study can be used to develop mathematical constitutive models of the multilayer separator material for subsequent numerical simulations and design.

Subwavelength resolution from multilayered structure (Conference Presentation)

NASA Astrophysics Data System (ADS)

Cheng, Bo Han; Jen, Yi-Jun; Liu, Wei-Chih; Lin, Shan-wen; Lan, Yung-Chiang; Tsai, Din Ping

2016-10-01

Breaking optical diffraction limit is one of the most important issues needed to be overcome for the demand of high-density optoelectronic components. Here, a multilayered structure which consists of alternating semiconductor and dielectric layers for breaking optical diffraction limitation at THz frequency region are proposed and analyzed. We numerically demonstrate that such multilayered structure not only can act as a hyperbolic metamaterial but also a birefringence material via the control of the external temperature (or magnetic field). A practical approach is provided to control all the diffraction signals toward a specific direction by using transfer matrix method and effective medium theory. Numerical calculations and computer simulation (based on finite element method, FEM) are carried out, which agree well with each other. The temperature (or magnetic field) parameter can be tuned to create an effective material with nearly flat isofrequency feature to transfer (project) all the k-space signals excited from the object to be resolved to the image plane. Furthermore, this multilayered structure can resolve subwavelength structures at various incident THz light sources simultaneously. In addition, the resolution power for a fixed operating frequency also can be tuned by only changing the magnitude of external magnetic field. Such a device provides a practical route for multi-functional material, photolithography and real-time super-resolution image.

Efficient optical nonlinear Langmuir-Blodgett films: roles of matrix molecules

NASA Astrophysics Data System (ADS)

Ma, Shihong; Lu, Xingze; Liu, Liying; Han, Kui; Wang, Wencheng; Zhang, Zhi-Ming

1996-10-01

A novel bifat-chain amphiphilic molecule nitrogencrown (NC) was adopted as an inert material for fabrication of optical nonlinear Langmuir-Blodgett (LB) multilayers. Structural improvement in the Z-type mixed fullerene derivative (C60-Be)/NC LB multilayers samples was realized by insertion of the C60-Be molecules between two hydrophobic chains of the NC molecules. The relatively large third-order susceptibility (chi) (3)xxxx(- 3(omega) ;(omega) ,(omega) ,(omega) ) equals 2.9 multiplied by 10-19 M2V-2 (or 2.1 multiplied by 10-11 esu) was deduced by measuring third harmonic generation (THG) from the C60-Be samples. The second harmonic generation (SHG) intensity increased quadratically with the bilayer number (up to 116 bilayers) in Y-type hemicyanine (HEM)/NC interleaving LB multilayers due to improvement of the structural properties by insertion of the long hydrophobic tail of HEM molecules between two chains of NC molecules. The second-order susceptibility (chi) (2)zxx(-2(omega) ;(omega) ,(omega) ) equals 18 pM V-1 (or 4.35 multiplied by 10-8 esu) was obtained by measuring SHG from the HEM samples. The NC molecule has attractive features as a matrix material in fabrications of LB multilayers made from optically nonlinear materials with hydrophobic long tails or ball-like molecules.

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.

Characterizing dielectric tensors of anisotropic materials from a single measurement

NASA Astrophysics Data System (ADS)

Smith, Paula Kay

Ellipsometry techniques look at changes in polarization states to measure optical properties of thin film materials. A beam reflected from a substrate measures the real and imaginary parts of the index of the material represented as n and k, respectively. Measuring the substrate at several angles gives additional information that can be used to measure multilayer thin film stacks. However, the outstanding problem in standard ellipsometry is that it uses a limited number of incident polarization states (s and p). This limits the technique to isotropic materials. The technique discussed in this paper extends the standard process to measure anisotropic materials by using a larger set of incident polarization states. By using a polarimeter to generate several incident polarization states and measure the polarization properties of the sample, ellipsometry can be performed on biaxial materials. Use of an optimization algorithm in conjunction with biaxial ellipsometry can more accurately determine the dielectric tensor of individual layers in multilayer structures. Biaxial ellipsometry is a technique that measures the dielectric tensors of a biaxial substrate, single-layer thin film, or multi-layer structure. The dielectric tensor of a biaxial material consists of the real and imaginary parts of the three orthogonal principal indices (n x + ikx, ny +iky and nz + i kz) as well as three Euler angles (alpha, beta and gamma) to describe its orientation. The method utilized in this work measures an angle-of-incidence Mueller matrix from a Mueller matrix imaging polarimeter equipped with a pair of microscope objectives that have low polarization properties. To accurately determine the dielectric tensors for multilayer samples, the angle-of-incidence Mueller matrix images are collected for multiple wavelengths. This is done in either a transmission mode or a reflection mode, each incorporates an appropriate dispersion model. Given approximate a priori knowledge of the dielectric tensor and film thickness, a Jones reflectivity matrix is calculated by solving Maxwell's equations at each surface. Converting the Jones matrix into a Mueller matrix provides a starting point for optimization. An optimization algorithm then finds the best fit dielectric tensor based on the measured angle-of-incidence Mueller matrix image. This process can be applied to polarizing materials, birefringent crystals and the multilayer structures of liquid crystal displays. In particular, the need for such accuracy in liquid crystal displays is growing as their applications in industry evolve.

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.

Thermal stress prediction in mirror and multilayer coatings.

PubMed

Cheng, Xianchao; Zhang, Lin; Morawe, Christian; Sanchez Del Rio, Manuel

2015-03-01

Multilayer optics for X-rays typically consist of hundreds of periods of two types of alternating sub-layers which are coated on a silicon substrate. The thickness of the coating is well below 1 µm (tens or hundreds of nanometers). The high aspect ratio (∼10(7)) between the size of the optics and the thickness of the multilayer can lead to a huge number of elements (∼10(16)) for the numerical simulation (by finite-element analysis using ANSYS code). In this work, the finite-element model for thermal-structural analysis of multilayer optics has been implemented using the ANSYS layer-functioned elements. The number of meshed elements is considerably reduced and the number of sub-layers feasible for the present computers is increased significantly. Based on this technique, single-layer coated mirrors and multilayer monochromators cooled by water or liquid nitrogen are studied with typical parameters of heat-load, cooling and geometry. The effects of cooling-down of the optics and heating of the X-ray beam are described. It is shown that the influences from the coating on temperature and deformation are negligible. However, large stresses are induced in the layers due to the different thermal expansion coefficients between the layer and the substrate materials, which is the critical issue for the survival of the optics. This is particularly true for the liquid-nitrogen cooling condition. The material properties of thin multilayer films are applied in the simulation to predict the layer thermal stresses with more precision.

Investigation of fiber tilt in paperboard

Treesearch

John M. Considine; David W. Vahey

2008-01-01

The introduction of short, tilted rods to reinforce polymer composite laminates has resulted in near doubling the strength of lap shear specimens. Paperboard is predominantly a multi-layered structure, similar to composite laminates in many ways. Improved bonding between layers should have a positive influence on mechanical performance. Tilted fibers, or z-direction...

Thermal analysis of continuous and patterned multilayer films in the presence of a nanoscale hot spot

NASA Astrophysics Data System (ADS)

Juang, Jia-Yang; Zheng, Jinglin

2016-10-01

Thermal responses of multilayer films play essential roles in state-of-the-art electronic systems, such as photo/micro-electronic devices, data storage systems, and silicon-on-insulator transistors. In this paper, we focus on the thermal aspects of multilayer films in the presence of a nanoscale hot spot induced by near field laser heating. The problem is set up in the scenario of heat assisted magnetic recording (HAMR), the next-generation technology to overcome the data storage density limit imposed by superparamagnetism. We characterized thermal responses of both continuous and patterned multilayer media films using transient thermal modeling. We observed that material configurations, in particular, the thermal barriers at the material layer interfaces crucially impact the temperature field hence play a key role in determining the hot spot geometry, transient response and power consumption. With a representative generic media model, we further explored the possibility of optimizing thermal performances by designing layers of heat sink and thermal barrier. The modeling approach demonstrates an effective way to characterize thermal behaviors of micro and nano-scale electronic devices with multilayer thin film structures. The insights into the thermal transport scheme will be critical for design and operations of such electronic devices.

Stable aqueous dispersions of functionalized multi-layer graphene by pulsed underwater plasma exfoliation of graphite

NASA Astrophysics Data System (ADS)

Meyer-Plath, Asmus; Beckert, Fabian; Tölle, Folke J.; Sturm, Heinz; Mülhaupt, Rolf

2016-02-01

A process was developed for graphite particle exfoliation in water to stably dispersed multi-layer graphene. It uses electrohydraulic shockwaves and the functionalizing effect of solution plasma discharges in water. The discharges were excited by 100 ns high voltage pulsing of graphite particle chains that bridge an electrode gap. The underwater discharges allow simultaneous exfoliation and chemical functionalization of graphite particles to partially oxidized multi-layer graphene. Exfoliation is caused by shockwaves that result from rapid evaporation of carbon and water to plasma-excited gas species. Depending on discharge energy and locus of ignition, the shockwaves cause stirring, erosion, exfoliation and/or expansion of graphite flakes. The process was optimized to produce long-term stable aqueous dispersions of multi-layer graphene from graphite in a single process step without requiring addition of intercalants, surfactants, binders or special solvents. A setup was developed that allows continuous production of aqueous dispersions of flake size-selected multi-layer graphenes. Due to the well-preserved sp2-carbon structure, thin films made from the dispersed graphene exhibited high electrical conductivity. Underwater plasma discharge processing exhibits high innovation potential for morphological and chemical modifications of carbonaceous materials and surfaces, especially for the generation of stable dispersions of two-dimensional, layered materials.

Modeling of Interface and Internal Disorder Applied to XRD Analysis of Ag-Based Nano-Multilayers.

PubMed

Ariosa, Daniel; Cancellieri, Claudia; Araullo-Peters, Vicente; Chiodi, Mirco; Klyatskina, Elizaveta; Janczak-Rusch, Jolanta; Jeurgens, Lars P H

2018-06-20

Multilayered structures are a promising route to tailor electronic, magnetic, optical, and/or mechanical properties and durability of functional materials. Sputter deposition at room temperature, being an out-of-equilibrium process, introduces structural defects and confers to these nanosystems an intrinsic thermodynamical instability. As-deposited materials exhibit a large amount of internal atomic displacements within each constituent block as well as severe interface roughness between different layers. To access and characterize the internal multilayer disorder and its thermal evolution, X-ray diffraction investigation and analysis are performed systematically at differently grown Ag-Ge/aluminum nitride (AlN) multilayers (co-deposited, sequentially deposited with and without radio frequency (RF) bias) samples and after high-temperature annealing treatment. We report here on model calculations based on a kinematic formalism describing the displacement disorder both within the multilayer blocks and at the interfaces to reproduce the experimental X-ray diffraction intensities. Mixing and displacements at the interface are found to be considerably reduced after thermal treatment for co- and sequentially deposited Ag-Ge/AlN samples. The application of a RF bias during the deposition causes the highest interface mixing and introduces random intercalates in the AlN layers. X-ray analysis is contrasted to transmission electron microscopy pictures to validate the approach.

Thermoelectric Signal Enhancement by Reconciling the Spin Seebeck and Anomalous Nernst Effects in Ferromagnet/Non-magnet Multilayers

PubMed Central

Lee, Kyeong-Dong; Kim, Dong-Jun; Yeon Lee, Hae; Kim, Seung-Hyun; Lee, Jong-Hyun; Lee, Kyung-Min; Jeong, Jong-Ryul; Lee, Ki-Suk; Song, Hyon-Seok; Sohn, Jeong-Woo; Shin, Sung-Chul; Park, Byong-Guk

2015-01-01

The utilization of ferromagnetic (FM) materials in thermoelectric devices allows one to have a simpler structure and/or independent control of electric and thermal conductivities, which may further remove obstacles for this technology to be realized. The thermoelectricity in FM/non-magnet (NM) heterostructures using an optical heating source is studied as a function of NM materials and a number of multilayers. It is observed that the overall thermoelectric signal in those structures which is contributed by spin Seebeck effect and anomalous Nernst effect (ANE) is enhanced by a proper selection of NM materials with a spin Hall angle that matches to the sign of the ANE. Moreover, by an increase of the number of multilayer, the thermoelectric voltage is enlarged further and the device resistance is reduced, simultaneously. The experimental observation of the improvement of thermoelectric properties may pave the way for the realization of magnetic-(or spin-) based thermoelectric devices. PMID:26020492

Design of radiation resistant metallic multilayers for advanced nuclear systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhernenkov, Mikhail, E-mail: zherne@bnl.gov, E-mail: gills@bnl.gov; Gill, Simerjeet, E-mail: zherne@bnl.gov, E-mail: gills@bnl.gov; Stanic, Vesna

2014-06-16

Helium implantation from transmutation reactions is a major cause of embrittlement and dimensional instability of structural components in nuclear energy systems. Development of novel materials with improved radiation resistance, which is of the utmost importance for progress in nuclear energy, requires guidelines to arrive at favorable parameters more efficiently. Here, we present a methodology that can be used for the design of radiation tolerant materials. We used synchrotron X-ray reflectivity to nondestructively study radiation effects at buried interfaces and measure swelling induced by He implantation in Cu/Nb multilayers. The results, supported by transmission electron microscopy, show a direct correlation betweenmore » reduced swelling in nanoscale multilayers and increased interface area per unit volume, consistent with helium storage in Cu/Nb interfaces in forms that minimize dimensional changes. In addition, for Cu/Nb layers, a linear relationship is demonstrated between the measured depth-dependent swelling and implanted He density from simulations, making the reflectivity technique a powerful tool for heuristic material design.« less

Thermoelectric Signal Enhancement by Reconciling the Spin Seebeck and Anomalous Nernst Effects in Ferromagnet/Non-magnet Multilayers.

PubMed

Lee, Kyeong-Dong; Kim, Dong-Jun; Yeon Lee, Hae; Kim, Seung-Hyun; Lee, Jong-Hyun; Lee, Kyung-Min; Jeong, Jong-Ryul; Lee, Ki-Suk; Song, Hyon-Seok; Sohn, Jeong-Woo; Shin, Sung-Chul; Park, Byong-Guk

2015-05-28

The utilization of ferromagnetic (FM) materials in thermoelectric devices allows one to have a simpler structure and/or independent control of electric and thermal conductivities, which may further remove obstacles for this technology to be realized. The thermoelectricity in FM/non-magnet (NM) heterostructures using an optical heating source is studied as a function of NM materials and a number of multilayers. It is observed that the overall thermoelectric signal in those structures which is contributed by spin Seebeck effect and anomalous Nernst effect (ANE) is enhanced by a proper selection of NM materials with a spin Hall angle that matches to the sign of the ANE. Moreover, by an increase of the number of multilayer, the thermoelectric voltage is enlarged further and the device resistance is reduced, simultaneously. The experimental observation of the improvement of thermoelectric properties may pave the way for the realization of magnetic-(or spin-) based thermoelectric devices.

Manufacture of multi-layer woven preforms

NASA Technical Reports Server (NTRS)

Mohamed, M. H.; Zhang, Z.; Dickinson, L.

1988-01-01

This paper reviews current three-dimensional weaving processes and discusses a process developed at the Mars Mission Research Center of North Carolina State University to weave three-dimensional multilayer fabrics. The fabrics may vary in size and complexity from simple panels to T-section or I-section beams to large stiffened panels. Parameters such as fiber orientation, volume fraction of the fiber required in each direction, yarn spacings or density, etc., which determine the physical properties of the composites are discussed.

Engineering the Structure and Properties of DNA-Nanoparticle Superstructures Using Polyvalent Counterions.

PubMed

Chou, Leo Y T; Song, Fayi; Chan, Warren C W

2016-04-06

DNA assembly of nanoparticles is a powerful approach to control their properties and prototype new materials. However, the structure and properties of DNA-assembled nanoparticles are labile and sensitive to interactions with counterions, which vary with processing and application environment. Here we show that substituting polyamines in place of elemental counterions significantly enhanced the structural rigidity and plasmonic properties of DNA-assembled metal nanoparticles. These effects arose from the ability of polyamines to condense DNA and cross-link DNA-coated nanoparticles. We further used polyamine wrapped DNA nanostructures as structural templates to seed the growth of polymer multilayers via layer-by-layer assembly, and controlled the degree of DNA condensation, plasmon coupling efficiency, and material responsiveness to environmental stimuli by varying polyelectrolyte composition. These results highlight counterion engineering as a versatile strategy to tailor the properties of DNA-nanoparticle assemblies for various applications, and should be applicable to other classes of DNA nanostructures.

Supra-Nanoparticle Functional Assemblies through Programmable Stacking

DOE PAGES

Tian, Cheng; Cordeiro, Marco Aurelio L.; Lhermitte, Julien; ...

2017-05-25

The quest for the by-design assembly of material and devices from nanoscale inorganic components is well recognized. Conventional self-assembly is often limited in its ability to control material morphology and structure simultaneously. We report a general method of assembling nanoparticles in a linear “pillar” morphology with regulated internal configurations. Our approach is inspired by supramolecular systems, where intermolecular stacking guides the assembly process to form diverse linear morphologies. Programmable stacking interactions were realized through incorporation of DNA coded recognition between the designed planar nanoparticle clusters. This resulted in the formation of multilayered pillar architectures with a well-defined internal nanoparticle organization.more » Furthermore, by controlling the number, position, size, and composition of the nanoparticles in each layer, a broad range of nanoparticle pillars were assembled and characterized in detail. In addition, we demonstrated the utility of this stacking assembly strategy for investigating plasmonic and electrical transport properties.« less

Supra-Nanoparticle Functional Assemblies through Programmable Stacking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Cheng; Cordeiro, Marco Aurelio L.; Lhermitte, Julien

The quest for the by-design assembly of material and devices from nanoscale inorganic components is well recognized. Conventional self-assembly is often limited in its ability to control material morphology and structure simultaneously. We report a general method of assembling nanoparticles in a linear “pillar” morphology with regulated internal configurations. Our approach is inspired by supramolecular systems, where intermolecular stacking guides the assembly process to form diverse linear morphologies. Programmable stacking interactions were realized through incorporation of DNA coded recognition between the designed planar nanoparticle clusters. This resulted in the formation of multilayered pillar architectures with a well-defined internal nanoparticle organization.more » Furthermore, by controlling the number, position, size, and composition of the nanoparticles in each layer, a broad range of nanoparticle pillars were assembled and characterized in detail. In addition, we demonstrated the utility of this stacking assembly strategy for investigating plasmonic and electrical transport properties.« less